Pulp and Paper Canada January / February 2010

January/February 2010

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CHEMICAL REPORT A Buyer’s Market with Few Buyers Biomass Gasification Begins at Kruger Environmental Leadership: Strathcona Paper JOURNAL OF RECORD, PULP AND PAPER TECHNICAL ASSOCIATION OF CANADA MCDONALD: The Effect of Dryer Operation on the Linting of Newsprint

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JANUARY/FEBRUARY 2010 Vol. 111, No. 1 A Business Information Group Publication ISSN 0316-4004

FEATURES

8 12 38

Biomass Gasification a Reality at Kruger Operational trials of Kruger Products’ biomass gasification system have begun. A cleaner, greener, and cheaper way to fire steam boilers in the pulp and paper sector will be showcased at this West Coast tissue mill in 2010.

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Chemical Report: A Buyer’s Market with Few Buyers Demand for basic chemicals and resins plummeted in 2009. Producers of most chemicals had to scramble to reduce output and hold the inventory buildup to manageable levels. Chemical sales are expected to recover modestly this year.

A History of Green Choices Respect for the environment has been standard operating procedure for years at Strathcona Papers’ recycled paperboard mill.

TECHNICAL PAPERS

15

BIOMASS GASIFICATION

CHEMICAL REPORT

12

STRATHCONA PAPER

38

PAPTAC Abstracts A brief introduction to some of the technical papers available from the Pulp and Paper Technical Association of Canada at www.paptac.ca TEMPO-Mediated Oxidation to Improve Deinked Pulp Quality Oxidation improved tensile and burst strength, while tear and brightness diminished.

By J. Leroux, C. Daneault, and B. Chabot

23 T he Effect of Dryer Section Operation on the Linting Propensity of Newsprint Dryer surface temperature is a critical factor. On some paper machines, simple modifications can decrease the paper’s linting tendency.

By J.D. McDonald and M.V. Tchepel

28 S urface Characterization and Surface Modification of Mechanical Pulp Fibres Preliminary results show that surface peeling, white-rot fungus, and xylanase can improve the interfibre bonding of CTMP fibres.

By K. Li, X. Kei, L. Lu, and C. Camm

MISSION STATEMENT:

IN EVERY ISSUE

To promote the pulp and paper industry in Canada by publishing news of the people and their innovations in research, technology, management and financing, as well as forecasts of future trends.

Authorized to publish papers of the Pulp and Paper Technical Association of Canada, which are identified by the symbol

Serving the industry since 1903.

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4 6 33 34 34

Guest Editorial News Calendar Technology News Classified Ads

January/February 2010 PULP & PAPER CANADA

3

GUEST EDITORIAL

It’s a tough industry everywhere

I

t’s no secret that Canada’s forest sector has been on a perpetual downward slide. For close to a decade, earnings have slumped and mills have closed.

The aggregate Q3 losses of $632 million for Canadian forest and paper companies announced recently by PricewaterhouseCoopers may have resulted in a collective sigh of dismay, but such dismal reports no longer raise industry eyebrows.

However, as PricewaterhouseCoopers’ Craig Campbell points out, this is not a “Canadian” problem confined to our borders. It’s a tough industry to make a buck in around the world.

As leader of PwC’s Performance Improvement Practice for the global forest and paper industry, Campbell speaks from experience.

“We’ve consistently lost money in this industry for the last two to three years,” he grants. It is this fact alone that paints a more dire picture for Canada’s forest sector than for other industries, such as the automotive sector, for example. Businesses that were profitable before the economic collapse of 2008 have a better shot at climbing back out of the hole than enterprises that were struggling to stay in the black before the meltdown. “We know that forestry operates on a cyclical system of downturns with a three- to six-year cycle. But when the recession hit, we were already in the trenches,” Campbell says.

Who is to blame, if anyone, for the fact that the nine largest public forest and paper companies in western Canada posted losses of $210 million for the third quarter of 2009?

Should we be turning an accusing finger inwards for the $422 million third-quarter loss of the six largest forestry and paper companies in the eastern part of the country? Campbell thinks perhaps not.

While it indisputably remains that Canadian neglected, for a number of reasons, to invest in new businesses, plants, and to develop opportunities overseas, other regions whose forestry sectors are widely considered “successful” are not far ahead in terms of profits.

“They aren’t blowing their lights out in South America,” Campbell notes. While this region typically enjoys a 10% ROCE (return on capital employed), Canada and the U.S. stand at an approximate 4-5% ROCE. “While Brazil is doing the best, that’s largely because their climate allows trees to grow extremely quickly, and that has drawn the eyes of investors,” Campbell says. “We might be a little behind in terms of creativity, but there is no predominant model of success and there is no one country or company that has this all figured out. It’s a tough industry around the world.”

Even Canada’s paucity of creativity is showing signs of replenishment with advances in bio-energy and transition through mergers. “We’re going to see a lot of change,” Campbell cautions. But as Winston Churchill once said, there is nothing wrong with change, if it is in the right direction.

Heather Lynch

EDITORIAL Editor CINDY MACDONALD 416-510-6755 cindy@pulpandpapercanada.com Contributing Editors HEATHER LYNCH

Sustaining member, Pulp and Paper Technical Association of Canada; Member, Canadian Business Press and Audit Bureau of Circulation.

ADVISORY BOARD Richard Foucault Greg Hay Dr. Richard Kerekes Barbara van Lierop Dr. David McDonald Dennis McNinch Dr. Yonghao Ni Bryant Prosser Dr. Paul Stuart Ross Williams

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PULP & PAPER CANADA

January/February 2010

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INDUSTRY NEWS I N T E R N AT I O N A L

Chinese rayon producer buys minority interest in Neucel Specialty Cellulose

PORT ALICE, B.C. — Zhejiang Fulida Ltd. has taken a direct minority investment in Neucel Specialty Cellulose Ltd. and signed a long-term supply agreement to procure Neucel’s chemical cellulose product. Fulida is one of the leading producers of rayon in the world.

Neucel plans to use the investment to accelerate its capital plan targeted mainly at capacity expansion in addition to cost and quality improvements.

“This partnership will enable us to gain an improved market presence in China and solidify our strong position in both the viscose and specialty markets,” said Bob Taylor, president and CEO of Neucel.

STOPS, STARTS, CHANGES

Catalyst Paper has curtailed indefinitely its Crofton No. 1 paper machine due to weak newsprint and directory paper demand. The machine, which produces 140,000 tonnes of commodity grades on an annualized basis, was temporarily idled on December 23, 2009 for the holiday period.

In a related move, the company’s paper recycling facility in Coquitlam, which supplies the Crofton paper machines with de-inked pulp, will be indefinitely shutdown in mid-February. Approximately 70 employees – 36 at Crofton – will be laid off as a result of these curtailments.

“There was a steep decline in market demand for the products made at our Crofton paper mill in the past year and the consumption outlook for these commodity grades remains weak. Reduced

“Viscose rayon fibre production capacity has increased greatly in China and competition has become intense.

With the relationship with Neucel, Fulida gains a smooth and stable supply of dissolving pulp materials,” said Jainer Qi, CEO of Fulida.

Neucel plans to deploy the available capital immediately to keep pace with the high customer demand in the chemical cellulose market. The company notes that this capital will complement the funding provided by the Government of Canada’s Pulp and Paper Green Transformation Program to further reduce its energy consumption. recycled pulp requirements, combined with the higher cost and constrained availability of quality recovered paper are contributing factors in our decision to indefinitely close our paper recycling facility,” said Richard Garneau, president and chief executive officer.

pulp mill had been successfully concluded. With this new agreement in place and market conditions for pulp improving, the Chetwynd mill was to be ramped up to full production by February.

The mill, which produces high yield pulp, had been shut down since February 2009. It employs roughly 160 people, of whom 115 are covered by the new collective agreement.

AbitibiBowater briefly halted paper production at its pulp mill in Fort Frances, Ont., after the mill’s effluent treatment system exceeded it daily biochemical oxygen demand (BOD) limit on Jan. 19. “Because of that, we had to shut down the mill to be in accordance with applicable laws and regulations,” said Jean-Philippe Cote, director of public affairs and government relations with AbitibiBowater. The mill restarted production several days later.

Domtar Corp. will be dismantling its permanently closed Prince Albert, Saskatchewan pulp mill. The Prince Albert pulp and paper mill was permanently closed in the first quarter of 2006 and has not been operated since. The dismantling of the paper machine and converting equipment was completed in 2008 and the dismantling of the remaining assets is expected to start in early 2010.

PEOPLE

In early February, AbitibiBowater restarted paper machine No.5 at its Thunder Bay plant. About 170 employees have returned to work. Company spokesman Jean-Philippe Cote attributes the restart to headway on the labour front and commitments from the Ontario government regarding wood supply and biomass.

Catalyst Paper announced that Richard Garneau, the company’s chief executive officer, will be leaving the company on April 28, 2010, citing personal reasons.

“Mr. Garneau has been relentless in his drive to reduce Catalyst’s costs and improve its profitability,” says Michel Desbiens, chair of Catalyst’s board of directors. “On behalf of the board I want to thank Richard for his contributions and express our regret at his departure.” A search for a successor will begin immediately.

Tembec announced in December that negotiations for a new collective agreement with CEP local 448 representing workers at its Chetwynd, B.C. high yield

Patrick J. Moore, Smurfit-Stone Container Corporation’s Chairman of the Board and chief executive officer, has notified the board of directors that he

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PULP & PAPER CANADA January/February 2010

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INDUSTRY NEWS intends to retire within one year following the company’s emergence from Chapter 11 proceedings.

ArboraNano, the new network created

by FPInnovations and NanoQuébec, has appointed Pierre Lapointe as chairman of its Board of Directors. Lapointe is president and CEO of FPInnovations.

ArboraNano’s goal is to create a new Canadian bioeconomy based on innovative, highly-engineered, carbon-neutral products containing nanomaterials.

BIOMASS

FPInnovations and CRIBE join forces to develop forest bio-economy

MONTREAL — A new partnership has been created between the Center for Research and Innovation in the BioEconomy (CRIBE) and FPInnovations, to facilitate the adoption of innovative technologies related to the forest bioeconomy.

Aimed at the forest products sector in Ontario, the new partnership will employ existing infrastructure and engage industrial partners in developing bio-refinery pilot plants to evaluate promising technologies and new concepts and validate ideas relevant to the bio-economy.

“The Government of Ontario has recognized the need to move the province to the forefront of the commercialization of chemicals, fuels, fibres, and energy that can be produced from forests,” says Lorne Morrow, CEO for CRIBE. “There is a significant opportunity to move products derived from the forest up the product value chain, using our forest fibre to produce higher value, novel products while reducing costs of manufacture for the more traditional forest products.”

Pierre Lapointe, president and CEO for FPInnovations says the engineering and technical studies are focused on three alternatives: lignin, methanol, and hemicellulose. “Our aim is to identify technical and business challenges around extracting and reusing these products. I have great hope for this partnership and the new possibilities it represents for the Ontario forest industry.”

BANKRUPTCY

Fraser Papers sells specialty papers business

Having received no additional offers to purchase its specialty papers business, Fraser Papers Inc. has terminated the bid process and will work toward completing the purchase offer sponsored by the company’s secured creditors that was signed on December 22, 2009.

Under the terms of the purchase agreement, the unsecured creditors of Fraser Papers will receive ten-year promissory

notes and a 49% common equity interest in the new company. Brookfield Asset Management Inc., a secured creditor, will convert its claim into a 51% common equity interest in the new company, while the Government of New Brunswick has agreed to convert its US$35 million secured loan into equity in the form of preferred shares of the new company.

Fraser Papers is an integrated specialty paper company with operations in New Brunswick, Maine, New Hampshire, and Quebec.

LEGALITIES

Port Alberni suing Catalyst Paper for unpaid taxes

With the dawn of the new year came another skirmish in the B.C. tax revolt.

The City of Port Alberni is taking court action against Catalyst Paper to force the company to pay its municipal taxes.

Catalyst withheld its taxes in 2009, and challenged Port Alberni and three other municipalities in court last year, claiming their tax rates were unjust. The B.C. Supreme Court ruled in all four cases in favour of the cities.

Catalyst is reported to be appealing the decisions, but in the meantime, interest is accumulating on the unpaid balances, and Port Alberni has gone one step further. The city is suing Catalyst Paper to collect $3.3 million in back taxes plus 20% in late penalties, The Daily News of Nanaimo, B.C. reported January 7.

Court upholds TimberWest’s petition against Campbell River’s tax rate

TimberWest’s petition to the B.C. Supreme Court to set aside the City of Campbell River’s 2009 tax rates bylaw as it applies to managed forest land has succeeded. In the Reasons for Judgment handed down on Dec. 31, Madam Justice Gerow declared that the sum of $1,211,639 was unlawfully levied by the City on TimberWest. The portions of the bylaw affecting TimberWest’s managed forest lands and the related property tax notices have been set aside.

TimberWest is one of several B.C. forest products companies to revolt against property taxes in 2009, either by challenging the tax rates in court, or withholding taxes, or both.

Newfoundland won’t pursue legal action against AbitibiBowater

Newfoundland’s Justice Minister Felix Collins told the province’s members of parliament that the province has backed away from court action against AbitibiBowater, the Telegram newspaper reported in early December.

The province was looking to recoup what it has paid as severance to laid-off workers after AbibitiBowater shuttered its mill in Grand Falls-Windsor in the spring of 2009.

Lockout over at Tembec Pine Falls; mill remains idle

Although the Manitoba Labour Board put an end to the employee lockout at Tembec’s Pine Falls newsprint mill, employees will not be returning to work.

Tembec announced in December that the mill is up for sale, and it will remain idle until it is sold.

The board’s decision ended a fourand-a-half-month lockout involving more than 250 employees. The Winnipeg Free Press reports that the decision will likely prompt the company to issue layoff notices, which will let workers apply for employment insurance benefits.

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January/February 2010 PULP & PAPER CANADA

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BIOMASS

Biomass Gasification a Reality at Kruger Construction is finished, and operational trials of Kruger Products’ biomass gasification system have begun. The technology developed by Nexterra is expected to be a cleaner, cheaper method of firing steam boilers at pulp and paper facilities.

By David Holehouse

A

cleaner, greener, and cheaper way to fire steam boilers in the pulp and paper sector will be showcased at a West Coast tissue mill in 2010.

Individuals will have the opportunity

to see for themselves how a biomass gasification system works in an industrial setting at the Kruger Products Limited tissue mill in New Westminster, B.C. The system in question was developed by Nexterra Energy Systems Corp. It started

up in late 2009 and is expected to be ready for an open house in June 2010.

Kruger engineering manager Charles Leclerc anticipates significant benefits from the company’s investment in the new technology. For example, a reduc-

The new gasifiers are located between the existing precipitator and the building.

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PULP & PAPER CANADA January/February 2010

pulpandpapercanada.com

TM

BIOMASS tion of provincial carbon emission taxes of $380,000 in 2010 alone, increasing annually to $580,000 by 2012. Greenhouse gas emissions will drop by 22,000 tonnes CO2 equivalent annually. Particulate emissions should be “virtually zero.”

The heat efficiency of the new system is expected to be double that of the mill’s old hog-fueled boiler, which was decommissioned in 2007 and replaced with a temporary natural gas boiler. Also, the Nexterra gasification system will cost $300,000 less per year to maintain and operate than the hog fuel boiler.

Compared to a natural gas boiler of equivalent capacity, the biomass gasification system will reduce fuel costs by well over $1 million a year.

Not bad for a major mill that needs every edge it can get to remain competitive in a volatile global economy and, equally important, meet the environmental expectations of its customers and its neighbours in the community.

“In an urban area, and in challenging economic times, we needed the cleanest and the most cost-competitive technology available,” says Frank van Biesen, Kruger Products’ vice-president, technology.

First time: biomass to syngas to steam

Biomass gasification at Kruger Products: Expected savings Maintenance & operation: $300,000/yr less than the previous hog-fueled boiler Carbon emission taxes: $380,000/yr less than the previous hog-fueled boiler Fuel costs: $1 million/yr less than the current natural gas boiler Kruger is part of a project consortium that includes national research organization FPInnovations and Nexterra Energy Systems Corp., with funding partners including Natural Resources Canada, Western Economic Development, and the province of British Columbia. The objective is to demonstrate commercial gasification technology at the mill scale, and for FPInnovations to conduct tests to verify and optimize performance.

“The intent of the government partners is to see if this is a system that could and should be adopted in other pulp and paper mills across Western Canada – potentially 10 of them,” says Jim Dangerfield, executive vice-president, FPInnovations.

“For us, this is part of our mandate – to develop and demonstrate technology that will help the industry reduce the cost of energy, which is a significant cost of production in the pulp and paper sector.”

The direct-fired gasification system was developed by Nexterra Energy Systems, which has been making steady inroads into clean renewable energy systems for the wood products industry in recent years. The custom-designed installation for the Kruger project is described as the first of its kind to demonstrate the directfiring of an industrial process boiler with a synthetic gas, or “syngas,” produced from gasification of wood residues.

Kruger’s new system replaces a 60-year-old conventional boiler that burned hog fuel (wood residues) to produce steam. The new system uses hog fuel at 5-60% moisture content, in gasifiers that process the fuel much more efficiently and cleanly.

Two gasifiers will convert biomass into clean-burning syngas, which is then transferred to an ignition chamber coupled directly to a watertube boiler. Capacity of the system will be 40,000 pounds/hour of medium pressure process steam, destined for a variety of uses on the site.

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PULP & PAPER CANADA January/February 2010

“The project will allow us to gather real-world numbers on the economics of substituting biomass for fossil fuels and, more importantly, gather life-cycle carbon emission reduction data,” Dangerfield explains. “The Nexterra system selected for this project is a platform technology that can be used in numerous applications. Replicating this technology at some key industrial sites in British Columbia alone could reduce greenhouse gas emissions by 200,000 tonnes annually.”

In addition to the 2010 open house and tours, industry members will be able to assess the new system through an ongoing knowledge transfer program managed by FPInnovations.

To be notified of open house details, contact: stephanie.troughton@fpinnovations.ca.

PPC David Holehouse is a freelance writer based in Alberta.

This shows the gasifier ductwork just prior to operational trials at Kruger Products’ New Westminster mill.

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A Buyer’s Market with Few Buyers Papermakers didn’t have much chance to take advantage of weaker chemical prices in 2009.

by Bob Douglas

Photo courtesy Air Products & Chemicals Inc.

T

here’s no light at the end of the tunnel, but Canadian pulp and paper producers must be thinking there’s an oncoming train anyway. Papermakers were already suffering when most resource industries were riding high. Now that the rest of the economy has tumbled, the paper sector is bleeding to death.

In its fall 2009 outlook, the Conference Board of Canada said it expected the country’s paper products industry to lose more than $1 billion in 2009. This would be the seventh consecutive year of losses for the industry and the largest on record.

“The recession brought on such a rapid decline in demand that paper producers were unable to cut production quickly enough, leading to rising inventories and falling prices,” said Michael Burt, associate director, Canadian industrial outlook. “What’s more, the industry will be permanently smaller because of lower demand for paper products going forward.”

The board estimated that annual production of paper products would fall by 14% in 2009. It expects even lower output this year, marking six consecutive years of decline.

According to Statistics Canada, capacity utilization in the paper industry stood at 81.2% during the fourth quarter of 2008. By the third quarter of 2009, it had fallen to 74.3%.

Demand for chemicals plummeted

The chemical industry also had a tough year, as demand for basic chemicals and 12

resins fell across the supply chain. Total Canadian chemical shipments fell by 35% to $16.6 billion in 2009 and producers of most chemicals had to scramble to reduce output and hold the inventory buildup to manageable levels. The drop in demand for chemicals was mainly attributed to declines in the automotive, housing, and pulp and paper industries. It is now believed that Canadian industrial production bottomed out in the second quarter of 2009. A tentative recovery appears to be underway in most sectors and chemical sales are expected to recover modestly this year.

According to a year-end survey of the Chemical Industry Association of Canada, chemical prices declined by about 12% last year, as customers demanded and won price concessions. But the price decline was not immediate or uniform.

Caustic soda prices had climbed steadily through 2008 to reach record levels of nearly US$1100/tonne by the end of the year. Demand fell off as industrial activity slowed, but the chloralkali industry was able to prop up high caustic prices by throttling back production: the operating rate in the first quarter was estimated at 70%, down from 91% in the corresponding period of 2008. Even at the end of April, caustic prices were over US$800/tonne. This level proved unsustainable. Caustic prices plummeted for five months, eventually falling below US$200/tonne in November.

The chloralkali industry expects ECU pricing (combined chlorine and caustic soda) in North America to trend upward

PULP & PAPER CANADA January/February 2010

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CHEMICAL REPORT this year after bottoming in the past third quarter. Prices won’t approach the record levels of early 2009, but sales volumes should improve. The supply in western Canada will grow in the second half when Canexus completes the technology conversion project at its North Vancouver plant. The project was 70% complete

by December. The company expects a 22% volume increase in 2010 as it ramps production up to the design level of 210 kt/yr of chlorine and 230 kt/yr of caustic, which represents a total capacity boost of 35%. Canexus also expects to complete a hydrochloric acid expansion at North Vancouver in June. That project will improve operating flexibility, as Canexus will have the option of diverting more chlorine to the acid plant during periods of strong caustic demand.

As long as high caustic prices continued to provide strong ECU returns, chloralkali producers were content to let chlorine prices slide to the $170/tonne range.

Once caustic prices fell and production was cut back, chlorine supply tightened noticeably. By the end of 2009, producers had been able to push chlorine prices back over the US$300/tonne level. This is consistent with 2004-2007 pricing levels.

Pulping chemicals: Sulphur volatile

Canadian lime production was consistently running 25-30% below 2008 levels through the first ten months of 2009.

Lime is used in the kraft pulping process to reconvert sodium carbonate into caustic soda. The byproduct, calcium carbonate, is recalcined in a kiln to recover lime for reuse. Most pulp mills operate their own kilns, so merchant producers typically only supply makeup lime to the industry. The cost of lime – either purchased or produced onsite – is closely related to the cost of energy.

Kraft pulping is a relatively small market for sodium sulphate, representing only about 15% of total demand in North America. The primary use of sodium sulphate worldwide is in powdered detergents, where it serves as a low-cost, inert, white filler. In North America, the home laundry market is moving towards liquid detergents, which do not contain any sodium sulphate. Asia and Latin America are major growth markets for sodium sulpulpandpapercanada.com

phate because of the increasing demand for packaged powder detergents. Despite these significant shifts, the equilibrium in the total market is unlikely to be upset. In pulping, the opportunity exists to replace sodium sulphate with emulsified sulphur and caustic soda when prices warrant.

The price of elemental sulphur went through the roof in 2008, approaching US$700/tonne in late summer. Then it crashed through the floor in 2009: by August, producers were barely able to get US$25/tonne. The overriding factor in these price swings was strong demand for

fertilizer production in India and China, which tailed off as the global economic outlook soured in the second half of 2008.

During the period of high prices, some Canadian sulfur stockpiles at sour gas and oil sands plants were remelted to meet increased demand for overseas trade until the market collapsed.

Sodium chlorate production reduced

Capacity rationalization carried out by sodium chlorate producers in the middle of the decade made for a tight market in

Chemical Supply Outlook Mill consumption (kilotonnes) 2008

Mill consumption (kilotonnes) 2009

Supply forecast

Sodium sulphate

48

42

balanced

Sulphur

49

43

balanced

Pulping chemicals Lime

Sulphur dioxide

Sodium hydroxide

Bleaching chemicals Chlorine

234

long

15

13

18

15

balanced

54

46

long

228

Sodium chlorate

565

Sulphuric acid

468

Sulphur dioxide

202

Hydrogen peroxide 215

197

488 405 186

balanced to long

balanced balanced balanced

Sodium silicate

55

Sodium borohydride

15

13

balanced

Sodium hydroxide

359 536

310

463

balanced to long

Aluminum sulphate

33

30

balanced

Rosin size Kaolin

3

balanced

Other clays

702

3

85

80

balanced to long

278

264

Sodium hydrosulphite

Oxygen

48

Papermaking chemicals

Titanium dioxide

Calcium carbonate Starch

SB latex

16

125 42

52

long

42

656

14

116 40

balanced to long balanced

balanced to long

balanced to long balanced balanced balanced balanced

Some of the chemicals listed above have more than one application. The figures represent total mill consumption.

January/February 2010 PULP & PAPER CANADA

13

CHEMICAL REPORT 2007 and 2008. This eased considerably with reduced pulp production levels during 2009, but chlorate selling prices were reported to be up by about 10% for much of the year. As in 2005 and 2006, chlorate producers were quick to adjust production levels to match market conditions. Erco Worldwide idled its plant in Valdosta, Ga., for a period in the second quarter, while Eka Chemicals permanently closed a facility in Norway.

In Canada, Canexus permanently ceased operations at its plant at Bruderheim, Alta., in April. The closure of the 72-kt/yr plant was largely unexpected, but Canexus has gone on record as being committed to reviewing its sodium chlorate capacity on a location-by-location basis in light of the prevailing market conditions. The Bruderheim plant was commissioned in 1992 and had undergone at least two capacity expansions.

Output from the plant served the pulp industry in the area and product was also bagged for export to the U.S. The company said the Bruderheim site – located northeast of Edmonton – would continue to be used as a terminal operation to support regional chloralkali sales.

In its outlook for 2010, Canexus said sodium chlorate sales volumes in North America should be about 9% higher than in 2009, but this gain will be more than offset by lower realized prices. The company also noted that a period of relatively lower prices in the latter part of 2009 and into 2010 could result in the closure of higher-cost sodium chlorate production capacity on the continent, supporting supply/demand balance.

Sulphuric acid inventory built up

There was considerable upheaval in sulphuric acid markets during 2009. Demand was strong entering the year, but fell sharply as the global recession took hold.

By early March, Noranda’s sulphuric acid storage capacity was nearly full and its sales agent, Xstrata Canada, was unable to arrange for sales and/or temporary storage in quantities equal to the current rate of production. Consequently, production of sulphuric acid and zinc were reduced by approximately 20%. The curtailment continued until October. Another event that reduced the sulphuric acid inventory overhang was a strike at the Vale Inco 14

increase was production and distribution inefficiencies resulting from variations in customer requirements. Some mills are supplied by onsite oxygen plants operated by the supplier: the profitability of such operations would likely be compromised by fluctuating demand.

Prices for titanium dioxide remained fairly flat last year.

Photo courtesy DuPont Chemical.

operations in Sudbury, Ont. Of more lasting effect was the decision by Xstrata to shutter its Kidd metallurgical site near Timmins, Ont. This permanently eliminated two sulphuric acid plants with total capacity of 560 kt/yr, though these units had been running at reduced rates since 2008.

Also eliminated at Kidd was the sulphur dioxide plant, which was capable of producing 30 kt/yr but had only been producing half that amount in recent years. Chemtrade Logistics markets the sulphur dioxide from Kidd. The company said production has been sporadic, as the chemical is in a real oversupply situation, and the plant closure will go unnoticed.

Output from the plant primarily went to eastern Canadian paper mills, but some product was being shipped to the U.S. for other applications. Chemtrade described the sulphur dioxide market as mature.

The chemical is being substituted in pulp bleaching and water treatment applications with sodium hydrosulfite and sodium bisulfite. Users have been switching to avoid the some of the dangerous handling conditions with liquid sulphur dioxide.

Demand dips for hydrogen peroxide

After a 5% increase in 2008, Canadian production of hydrogen peroxide was down by nearly 20% in the first half of 2009. Pulp and paper is by far the dominant market for peroxide in Canada.

The chemical is used to bleach chemithermomechanical pulps and mechanical pulps for groundwood specialties. Recent demand growth has been driven by its use in deinking newsprint.

Industrial gas producers (Air Liquide, Praxair, Air Products) raised merchant prices for oxygen by 10% during the fourth quarter of 2009. It is interesting to note that one of the reasons given for the

PULP & PAPER CANADA January/February 2010

Prices rising for pigments and fillers

The leading suppliers of paper fillers, Imerys and KaMin, raised prices at the end of 2009 to cover rising costs in logistics, mining, chemicals, fuel, and power.

On average, prices went up by 5-7% for kaolin (including calcined products) and by 2-3% for ground calcium carbonate.

Surcharges linked to natural gas and/or crude oil prices remained in effect.

A gradual improvement in demand encouraged Kronos Worldwide, DuPont Titanium Technologies, Tronox, Huntsman, and Cristal Global to resume their efforts to raise prices during the summer. Nevertheless, indications are that prices remained fairly flat at US$1.04/lb through the second half of 2009.

A significant reduction in demand from the paper industry more than offset growth in other water treatment applications, so aluminum sulphate production in Canada was down by nearly 10% in the first half of 2009. Alum production had been on an upward trend, climbing by more than 20% in 2007 and a further 12% in 2008.

Sales of specialty chemicals used in pulp and paper were down in line with reduced mill production. There were no significant price increases for such products as sizing agents, wet strength additives and retention/drainage aids during the year, but BASF and Dow Chemical raised prices for emulsion polymers – including styrene-butadiene latex products – by 5-10 cents/pound during the P&PC summer.

Bob Douglas is publisher of Camford Chemical Report, a weekly newsletter on Canada’s chemical processing industries, and CPI Product Profiles, a series of 200 data sheets on markets for individual chemical products. Bob has more than 25 years of experience tracking developments in pulp and paper technologies and analyzing trends in chemical and energy supply, demand and prices. pulpandpapercanada.com

PAPTAC ABSTRACTS (Full peer-reviewed manuscripts available at www.paptac.ca)

Factors affecting Chloride and Potassium Removal Efficiency of a Recovery Boiler Precipitator Ash Treatment System

By C. Gonçalves, H. Tran and R. Shenassa

Facteurs modifiant l’efficacité de l’élimination du chlorure et du potassium d’un système de traitement des cendres du précipitateur d’une chaudière de récupération

Abstract: A laboratory study was performed to examine the main factors affecting the removal efficiency of chloride (Cl) and potassium (K) of ash treatment systems operated at a temperature between 60 and 100°C. The results show that the removal efficiency is directly proportional to the amounts of Cl and K in the liquid that have been separated from the ash-water slurry. For a given system, the Cl and K removal efficiency is determined by the concentration of Cl and K in the liquid and by the Degree of solid-liquid Separation (DS). DS, in turn, is greatly affected by the ash concentration in the slurry and the CO3 content of the ash.

Paper presented at the 2007 International Chemical Recovery Conference in Quebec, Que, May 29 – June 1, 2007.

Keywords: RECOVERY BOILER, FOULING, ASH TREATMENT, PRECIPITATOR ASH, CHLORIDE, POTASSIUM, CARBONATE, REMOVAL EFFICIENCY Full manuscript available at www.paptac.ca.

Enhancing Papermaking Properties of Secondary Fibres by Tempo-Mediated Oxidation

By C. Gomes, K.N. Law, C. Daneault, B. Chabot

Oxydation par TEMPO afin d’am´eliorer les propriétés des fibres secondaires lors de la fabrication

Abstract: A bleached virgin hardwood kraft pulp was refined and recycled one time in laboratory. Recycled samples were then oxidized using TEMPO (4-acetamido-2,2,6,6-tetramethylpiperidine-1-oxyl radical), sodium bromide and sodium hypochlorite, with variation of the latter’s concentration on each sample.

Results showed that all papermaking properties, particularly the tear index, were significantly improved at low NaOCl concentrations. At higher NaOCl charges the burst and tensile indices suffered little decrease, while the tear was strongly reduced.

Paper presented at the 95th PAPTAC Annual Meeting 2009 in Montreal, Que., February 3-4, 2009.

Keywords: RECYCLED FIBRES, TEMPO-MEDIATED OXIDATION, STRENGTH PROPERTIES, KRAFT PULP Full manuscript available at www.paptac.ca.

Potential Cost Benefit of Electricity Load Shifting when Designing Upgrades to an Integrated Newsprint Mill

By M. Janssen, K. Riemer, P. Stuart

Économie potentielle du déplacement de la charge électrique lors de l’optimisation d’une usine de papier journal intégrée Abstract: This article describes the application of an operationsdriven cost model for assessing the potential benefits of electricity load shifting in a TMP plant when designing upgrades to an integrated newsprint mill. The case study considered several retrofit design options for the upgrade of the mill by increasing deinked pulp (DIP) production and implementing cogeneration. Identifying the optimal load shifting profile resulted in an increase in the project NPV of $21 to $27 million depending on the alternative.

Sensitivity results show that considering load shifting in the design process may in some cases alter the best design choice. This is more likely to occur at high average electricity prices and a large differ-

pulpandpapercanada.com

ence between on- and off-peak electricity prices. Furthermore, applying load shifting when considering real-time prices reduces manufacturing costs with $2500/tonne when compared to the existing mill, at an extreme electricity price of $1045/MWh. Paper presented at the 94th PAPTAC Annual Meeting in Montreal, February 5-7, 2008.

Keywords: RETROFIT PROCESS DESIGN, COST MODELING, ELECTRICITY LOAD SHIFTING, INTEGRATED NEWSPRINT MILL. Full manuscript available at www.paptac.ca.

January/February 2010

PULP & PAPER CANADA

15

PAPTAC ABSTRACTS (Full peer-reviewed manuscripts available at www.paptac.ca)

Measurements of Pressure Pulses from Blades in a Gap Former

By R.W. Gooding, J.D. McDonald, A. Rompré and S.I. Green

Détermination des impulsions de pression des lames dans un formeur double toile

Abstract: Blades in a gap former induce pressure pulses on the passing fibre mat causing drainage and redistribution of fines and fibres. Pressure pulse measurements were made on a pilot paper machine for various wrap angles, blade shapes and fabric tensions. A typical pulse form had one pulse upstream of the blade and another over the blade with the magnitude of each depending on wrap angle, which is consistent with theory.

Knowledge of these pulse forms is a useful first step to enhancing paper quality.

Paper presented at the 90th PAPTAC Annual Meeting in Montreal, Que., January 26-29, 2004.

Keywords: GAP FORMER, PRESSURE PULSES, FORMING BLADE, WRAP ANGLE. Full manuscript available at www.paptac.ca.

Protocol for Evaluating Flotation Aids with a LaboratoryScale Flotation Column

By M. Ricard, G. Dorris, and C. Lapointe

Protocole d’évaluation des dispositifs de flottation à l’aide d’une colonne de flottation de laboratoire

Abstract: In order to identify the best surfactants for certain types of recovered paper blends, we have developed a useful tool for recyclers wanting to evaluate and compare flotation aids. With the addition of new features such as on-line air content measurement in a flotation column, this novel method measures the flotation rate constant and characterizes the performance of a flotation col-

16

PULP & PAPER CANADA

January/February 2010

A Survey of Pulp and Paper Mills: Operating and Effluent Quality in Relation to Fish Reproduction

By T. Kovacs, P. Martel, and B. O’Connor

Étude des usines de pâtes et papiers : Qualité de la production et des effluents en ce qui a trait à la reproduction des poissons

Abstract: While many studies have shown that pulp/paper mill effluents can influence fish reproduction, there are few leads for remedial strategies. To gain insights regarding solutions, effluents from nine mills were tested for effects on fish reproduction and characterized chemically. Most effluents affected fish reproduction, but the degree of the effects varied substantially.

Effluents with the lowest overall organic content (measured as BOD and total gas chromatography peak areas of effluent solvent extracts), probably resulting from spill control and efficient biotreatment systems, caused the least effects.

Paper presented at the 95th PAPTAC Annual Meeting 2009 in Montreal, Que., February 3-4, 2009.

Keywords: FISHES, REPRODUCTION, PULP MILLS, PAPER MILLS, EFFLUENTS, BIOLOGICAL TREATMENT, ACTIVATED SLUDGE PROCESS, AERATION, KRAFT MILLS, THERMOMECHANICAL PULPING (TMP), SURVEYS, BOD (BIOCHEMICAL OXYGEN DEMAND OR BIOLOGICAL OXYGEN DEMAND), CHEMICAL OXYGEN DEMAND, PHYTOSTEROLS, GAS CHROMATOGRAPHY Full manuscript available at www.paptac.ca.

lector. The method uses a small pilot flotation column that can be operated in either a continuous or batch mode. The column is set up for accurate measurement and control of air content, froth height, and air and liquid flows. On-line estimation of mean bubble diameter is also possible. Combining the information obtained from on-line and laboratory measurements will enable the evaluation of the flotation rate constant and two basic parameters governing pulp aeration and ink collection. It is only when both parameters are well controlled that precise and conclusive results are obtained. In this report, we provide examples of tests carried out using conventional fatty acid soaps for flotation of an ONP/ OMG pulp. During the development of the method, the contact time and temperature during the addition of anionic soaps were found to be critical.

Paper presented at the 95th PAPTAC Annual Meeting 2009 in Montreal, Que., February 3-4, 2009.

Keywords: FLOTATION, BRIGHTNESS, IMPURITIES, REMOVAL, DEINKING, EVALUATION, FINES, SURFACTANTS, WASTE PAPERS Full manuscript available at www.paptac.ca. pulpandpapercanada.com

PAPTAC ABSTRACTS (Full peer-reviewed manuscripts available at www.paptac.ca)

Retention Program and Wet End Chemistry Management with Focus on Quality and Efficiency of Modern Calendered Grades

By Przemyslaw Pruszynski

Programme de rétention et gestion de la chimie de la partie humide, en portant une attention particulière à la qualité et à l’efficacité des catégories calandrées modernes Abstract: Recent advances in calendering technology and demands on quality and production cost of supercalendered grades have created new requirements for process stability, formation, and sheet structure and system cleanliness. Supplying consistent and optimally structured sheet to the calender stack may allow the papermaker to improve results, especially with the most aggressive calendering processes.

Nalco Company has been focusing on a grade-specific approach in every major application. Some of Nalco’s applications specific to calendered grades of paper are described in this paper. This paper reviews the most important sheet properties, operational best practices and structure-properties relationships relevant for results of a calendering operation. Literature review, practical mill data as well as future development suggestions are also discussed in this paper.

Specialty chemicals suppliers have to focus beyond traditional performance indicators of retention programs such as retention value, white water consistency, drainage, etc. The new focus should be on

The Effect of Acetone Extraction on the Disruptive Shear Stress in Pine Thermomechanical Pulps

By M. Illikainen, E. Härkönen, J. Niinimäki

Effet de l’extraction d’acétone sur la contrainte de cisaillement disruptive dans les pâtes thermomécaniques de pin

Abstract: The effect of extractives on the disruptive shear stress in pine thermomechanical pulps was studied using the equipment of shear and compression. Compressibility and the disruptive shear stress in first thinning pine and sawmill pine thermomechanical pulps were studied at a temperature of 120°C. Additional experiments were done using the pulp from which extractives were removed by acetone extraction. The result of the study was that removal of extractives does not change the compressibility or disruptive shear stress in pulp.

Paper presented at the 2007 International Mechanical Pulping Conference, June 1,2007.

Keywords: EXTRACTIVES, ACETONE EXTRACTION, THERMOMECHANICAL PULP, TMP, COMPRESSIBILITY, DISRUPTIVE SHEAR STRESS. Full manuscript available at www.paptac.ca. pulpandpapercanada.com

better understanding how to, within existing limitations of furnish and papermaking equipment, assist the papermaker in delivering uniform (MD and CD), properly structured in ZD sheet, with proper surface topography and surface strength so that maximum quality and runnability benefits from calendering process can be reached.

Some general areas where such focus may result in significant benefits to the papermaker are discussed in this paper.

Keywords: SC PAPERS, SHEET STRUCTURE, FILLER DISTRIBUTION, FORMATION, GLOSS, SMOOTHNESS, BRIGHTNESS, SYSTEM STABILITY, PH, CATIONIC DEMAND, CONDUCTIVITY, PRINTABILITY, EXTRACTIVES CONTROL Paper presented at the 95th PAPTAC Annual Meeting 2009 in Montreal, Que., February 3-4, 2009.

Full manuscript available at www.paptac.ca.

Correction: There was an error with the authors’ names in an abstract published in the Dec. 2009 issue. The correct version follows:

Effect of the Final ECF Bleaching Stage on Eucalyptus Kraft Pulp Properties – A Comparison Between Hydrogen Peroxide and Chlorine Dioxide

By P.E.G. Loureiro, P.J. Ferreira, D.V. Evtuguin, M.G.V.S. Carvalho

L’effet du stade final de blanchiment sans chlore élémentaire sur les propriétés de la pâte kraft d’eucalyptus – une comparaison entre le peroxyde d’hydrogène et le dioxyde de chlore January/February 2010

PULP & PAPER CANADA

17

T1

DEINKED PULP

TEMPO-Mediated Oxidation to Improve Deinked Pulp Quality

By J. Leroux, C. Daneault, and B. Chabot Abstract: Deinked pulp slurries were oxidized with TEMPO (4-acetamido-2,2,6,6-tetramethylpiperidine1-oxyl radical), sodium bromide, and sodium hypochlorite under various conditions to improve both optical and strength properties. Oxidation treatments showed significant improvements for tensile and burst while tear was decreased. Pulp brightness was reduced due to pulp darkening from alkaline conditions used for oxidations. However, bleaching with hydrogen peroxide following the oxidation stage was found to recover the brightness loss.

T

he Canadian pulp and paper industry is currently experiencing a critical crisis which could have devastating effects on its future economic growth. The industry is facing enormous challenges. Among them, the high value of the Canadian currency compared to the U.S. dollar, the rising fuels costs, the low prices and the overcapacity of some grades are affecting the health of this major business sector. Quebec’s industry is also affected by the situation. Several local events can be singled out. Newsprint is still the dominating product manufactured by Quebec’s paper mills. However, the demand for newsprint in North America has steadily decreased during the last fifteen years due to maturation of the market [1]. Increases in energy and wood chips costs are also significantly affecting paper mills’ profitability. At the same time, paper manufacturers are forced to reduce their supply of virgin softwood fibre by 15-20% to comply with new forest management practices adopted by the government of Quebec [2]. To compensate for the reduction in virgin fibre supply and to reduce their production costs, mills are considering the use of higher deinked pulp content in their products. Although deinked pulps are largely used for the manufacture of newsprint, fine papers, tissue papers, and board, they are not commonly used in value-added papers (coated, supercalendered). Waste papers are mainly recovered in U.S. large urban centres. However, they are also in great demand by other countries, namely China. This strong demand generates pressure on secondary fibre accessibility that tends to increase waste paper prices and decrease secondary fibre quality.

Three main problems associated with deinked pulps are still limiting their use in value-added paper manufacturing. The lower bonding ability of deinked fibres is the first problem encoun18

PULP & PAPER CANADA January/February 2010

tered when using deinked pulps. This problem is attributed to a reduction of water-reswelling properties of deinked fibres [3,4]. Studies have shown that molecular-level structural changes of the cellulosic materials by thermal, hydrothermal, and repulping treatments are responsible for the hornification of the fibres that results in lower bonding ability [5]. It is also well known that fibres undergo various chemical and mechanical treatments along the deinking line, which might affect their physical properties [6]. The combined effect is thus responsible for the reduction of strength properties.

Residual ink is a major contributor to the reduced optical properties of deinked pulp fibres.

Residual ink particles can be attributed to both remaining ink particles on fibre surfaces, and also to ink particle redeposition [7]. Both phenomenon mainly occurr during waste paper repulping.

Several studies have shown that aging of offset inks during storage (heat and UV irradiation) is responsible for the lower deinkability of printed materials resulting in higher amounts of residual inks on deinked fibres [8,9]. This phenomena has been attributed to the acceleration of the autoxidation of the ink vehicle (mineral or vegetable oils) resulting in the formation of covalent bonds between ink and cellulose. Redeposition is the second phenomena involved during repulping of waste papers. Repulping conditions (especially repulping time), have been shown to affect redeposition by fractioning larger ink fragments into smaller particles [10,11]. They are then subjected to high shear in the repulper which promote their deposition on the outside surface of the fibre but also into the lumen of the fibre. They are then very difficult to remove resulting in a greyish pulp. Although peroxide bleaching can improve deinked pulp brightness, there is still

J. LEROUX Centre intégré en pâtes et papiers, Université du Québec à Trois-Rivières, Trois-Rivières, Que.

C. DANEAULT Canada Research Chair in Value-added Paper

B. CHABOT Centre intégré en pâtes et papiers, Université du Québec à Trois-Rivières, Trois-Rivières, Que. pulpandpapercanada.com

PEER REVIEWED a limit that cannot be exceeded without excessive costs.

Contaminant content is the third problem associated with deinked pulps. Some grades contain high levels of adhesives, waxes, and latexes that are released into process waters during deinking [12,13].

These substances are generally classified as macro and micro stickies. Both classes can affect papermachine runnability as well as product quality. As mentioned previously, the high demand for waste papers will contribute to decrease secondary fibre quality, resulting in higher contaminant levels.

Catalytic and selective oxidation of primary hydroxyl groups of pulp fibres using TEMPO has received much attention in recent years to improve pulp strength by introducing additional carboxylic groups on the fibre surface [14-17]. TEMPO (2,2,6,6-tetramethylpiperidine-1-oxy radical) is a water-soluble, stable, and commercially available nitroxyl radical reagent.

It is used as a catalytic oxidant with NaBr and NaOCl for conversion of primary hydroxyl groups of cellulose into carboxylic groups under aqueous conditions. The couple NaOCl/NaBr is a co-oxidizer system which allows the regeneration of the TEMPO. The cellulose is treated with those chemicals under alkaline conditions (pH around 10 and 11), yielding carboxylic acid sites on the cellulosic chain [14].

However, those studies were mainly focusing on chemical and to a lower extent on mechanical pulps.

To increase deinked pulp usage in value-added paper grades, it is imperative to improve both optical and physical properties of deinked fibres. The objective of this work is thus to study the oxidizing potential of the 4-acetamido-2,2,6,6tetramethylpiperidine-1-oxyl radical (TEMPO) to improve strength and optical properties of deinked fibres. A recent study has shown that TEMPO oxidation of TMP pulps has significantly improved the strength properties of handsheets made with mixtures of untreated and modified TMP fibres [17]. It is thus believed that oxidation of deinked fibres with TEMPO will also improve strength properties of deinked fibres. Since this product is a strong oxidizer, we also think that it could contribute to detaching residual ink particles on fibre surfaces resulting in better optical properties of deinked pulps. pulpandpapercanada.com

Table I. Chemical dosages for TEMPO oxidation of deinked pulps.

Charge TEMPO (%) 100 50 25 12.5

TEMPO (%w/w) 0.17 0.083 0.042 0.021

NaBr (%w/w)

NaOCl (%v/v)

32.0 15.8 7.9 3.96

8.3 5.0 2.5 1.25

EXPERIMENTAL

Materials The 4-acetamido TEMPO, sodium bromide, and other chemicals and solvents were of laboratory grades. They were purchased from Aldrich and used without any purification. Sodium hypochlorite was of commercial grade (5.5-6Â % active chlorine).

Deinked pulp (DIP) was provided by an Eastern Canadian paper mill. The pulp was produced from a mixture of 70% old newspapers (ONP) and 30% old magazines (OMG). The carboxylic acid groups content was determined by conductimetric titration (110 mmol/kg o.d pulp).

Methodology Figure 1 presents a schematic diagram of the procedures involved for experimentations.

Oxidation of pulp Oxidation of deinked pulp was carried out by mixing 60 g o.d. in 3 L of deionized water to make a 2% slurry consistency. The pH was adjusted to 10.5 with NaOH. The TEMPO was first diluted in water and added to the mixture according to the dosages required as indicated in Table I. Dosages of TEMPO, NaBr, and NaOCl were determined based on the ratio of chemicals added to the theoretical amount of primary alcohol groups found on the fibre surface.

It is assumed here that pulp is equivalent to cellulose. Therefore, the primary alcohol groups are those of the glucose units of cellulose. The appropriate amounts of sodium bromide and sodium hydroxide (see Table I) were first mixed and then added slowly to the pulp slurry maintained under agitation in a mixing container.

During chemicals addition, the pH of the slurry was maintained at 10.5 using a pH controller. The reaction was carried out for two hours. Finally, the reaction was stopped by adding 20 mL of ethanol to the slurry. The pulp was then filtered and reslushed. Then, the pH of the pulp slurry was decreased to 5.5 using HCl (1M). The pulp was filtered again and washed with

Fig. 1. Schematic diagram of the methodology.

deionized water three times to remove any residual chemicals.

Flotation A sample of the oxidized pulp was diluted to 0.5% consistency using deionized water.

The pH was adjusted to 9.5 using NaOH 1M solution, and the temperature was adjusted to 50°C using hot water. The free calcium ion content was then measured by titration with EDTA. Then, the free calcium ion was adjusted to 100 mg/L by adding the corresponding amount of calcium chloride in the pulp slurry. A surfactant (sodium oleate) was then added to the pulp slurry. The amount was 0.5% based on the dry fibre content. The slurry was stirred for 5 minutes and transferred to the flotation cell (6.5L). The slurry in the flotation cell was agitated at 1200 rpm, then air was injected at a flow rate of 3L/min. Flotation was carried out during 5 minutes. The froth was continuously collected in a beaker during the flotation.

After the flotation stage, the cleaned pulp remaining in the cell was recovered, the pH was adjusted to 5.5, and filtered in a buchner funnel. A sample of the thickened pulp was then used to make handsheets.

Bleaching In two series of experiments, a peroxide bleaching stage was carried out using

January/February 2010 PULP & PAPER CANADA

19

T2

T3

DEINKED PULP

Fig. 2. Effect of TEMPO concentration on breaking length.

either the oxidized pulp or the oxidized/ floated pulp samples (see Fig. 1). In both cases, the bleaching was carried out at 12% pulp consistency using 3% sodium silicate, 0.05% magnesium sulphate, 5% hydrogen peroxide and a total alkali ratio of 0.8. All chemicals were introduced in the pulp placed in a plastic bag and mixed for two minutes. The pulp was then preheated in a microwave oven. Then, the bag was sealed and transferred in a thermostated bath maintained at 70°C for 90 minutes.

After bleaching, the remaining peroxide in the pulp sample was neutralized using sodium metabisulphite until the pH was reduced to 5.5. The bleached pulp sample was filtered and used to make handsheets.

Handsheet formation and testing Standard handsheets (60 g/m2) of pulp samples after any treatments were made using a British handsheet machine according to PAPTAC Standard Testing Method C.4. Strength (PAPTAC Standard Testing Methods D.6H, D.8, D.9) and optical properties (PAPTAC Standard Testings Methods E.1, E.8P) were determined from these handsheets.

RESULTS AND DISCUSSION

Strength properties of handsheets Figure 2 presents the effect of TEMPO concentration on breaking length. For each series of experiments, the deinked pulp was first oxidized at the predetermined TEMPO concentration, then the oxidized pulp was either subjected to a flotation stage, a bleaching stage, or to flotation followed by bleaching. Results were compared to a blank experiment without any oxidizing treatment (first bar from the left in the 20

Fig. 3. Effect of TEMPO concentration on burst.

blank experiment group).

It is clear from Fig. 2 that TEMPO addition increased the breaking length of handsheets. Tensile was improved for the lowest TEMPO dosage (12.5%) to a constant value at higher dosages (compare bar 1 in each series of tests). On the other hand, peroxide bleaching also significantly improved tensile. Tensile increased for trials without TEMPO addition (bar 1 vs 3 in the blank series). The same tendency was observed for trials with TEMPO addition but the effect was slightly lower.

The higher tensile values obtained after the peroxide bleaching stage (bar 3 in each series of experiments) is probably the result of a combined effect of both TEMPO and peroxide addition, and the high alkalinity of the system. The variations observed after the flotation stage is probably attributed to the loss of fines in the reject but the effect was of minor importance compared to oxidation and bleaching stages.

Figure 3 shows the effect of TEMPO on burst. The trend pattern observed is very similar to breaking length except at higher TEMPO dosages (50%-100%).

The peroxide bleaching stage is also very effective at improving burst as it is clearly demonstrated for the blank. As for the breaking length, the flotation stage did not affected burst.

Tensile and burst are dependent on fibre-to-fibre bonding. It is also well known that hydrogen bonding is one of the main bonding mechanism responsible for strength properties [18]. Oxidation processes were carried out in these experiments to increase acidic groups concentration on the fibre surface in order

PULP & PAPER CANADA January/February 2010

to improve hydrogen bonding potential.

Previous results clearly showed that this objective was achieved.

Figure 4 presents the effect of TEMPO on tear. Results indicate that TEMPO oxidation reduced tear. The reduction was more important as the concentration of TEMPO was increased. The drop in tear was also more important after bleaching for trials when TEMPO was added.

The higher the concentration, the higher the drop in tear. The flotation stage did not affect the tearing resistance. Tear is reduced due to increasing amounts of carboxylic groups generated on the fibre surfaces by the oxidation with TEMPO. Since the tearing resistance is also dependent on fibre length [19], the effect was greater because the average fibre length of the deinked pulp used was low (0.6 mm).

Figure 5 presents the effect of TEMPO on the Young modulus of handsheets.

Results indicate that the elastic modulus was increasing with TEMPO addition levels. This can be attributed to the increase in carboxylic groups concentrations on the fibre surfaces resulting from the oxidation stage with TEMPO. Results show that the peroxide stage following oxidation of the pulp also improved the elastic modulus. However, the improvement was not constant for each series of experiments. As was the case for the other strength properties, the flotation stage did not significantly affect the elastic modulus.

Optical properties of handsheets Figure 6 presents the effect of TEMPO on brightness. It is clear that TEMPO oxidation had a dramatic effect on pulp brightness, with approximately 10 points pulpandpapercanada.com

PEER REVIEWED

Fig. 4. Effect of TEMPO concentration on tear.

Fig. 5. Effect of TEMPO concentration on Young modulus.

Fig. 6. Effect of TEMPO concentration on brightness.

Fig.7. Effect of TEMPO concentration on ERIC.

brightness drop between the blank without any TEMPO and the trial at 12.5% TEMPO. This was attributed to the alkali darkening effect resulting from the alkaline conditions prevailing during oxidation.

The effect was less important at higher TEMPO dosages but the brightness drop was still significant (compare bar 1 in each series of experiments). To compensate for this effect, a bleaching stage with peroxide at a constant dosage of 5% was carried out (bar 3 in each series). Results show that the bleaching stage was able to recover more than the brightness lost during the oxidation process. The phenomenon was similar at all TEMPO dosages. Of course the brightness gain was not significant for the blank experiments since no TEMPO was used.

A flotation stage was also carried out to remove ink particles that could have detached during the oxidation by TEMPO. The result could have a beneficial pulpandpapercanada.com

effect on pulp brightness. According to our results, the brightness gain was significant with a maximum value for a TEMPO dosage of 25%. However, the brightness gain decreased for higher TEMPO concentrations. The brightness gain was very similar to the gain observed for the blank experiment. Therefore, it was not possible to clearly establish if the TEMPO oxidation stage helped to detach residual ink particles from the fibre surface of deinked pulp. Unfortunately, it was not possible to exceed 68% brightness (the maximum value obtained for the trial without TEMPO). This seems to be the maximum value achievable within the limits of our experimental conditions. Further analysis will be needed to determine why it is not possible to exceed this value.

To further examine the effect of TEMPO on ink detachment, we have determined the level of residual ink on the fibre surface using the Effective Residual Ink

Concentration (ERIC).

Figure 7 shows the effect of TEMPO on ERIC values for the same experimental conditions. Results indicated that ERIC values decreased after each treatment. Flotation was particularly effective at reducing ERIC, especially after oxidation with TEMPO. However, it was also effective for the blank. Although a substantial reduction in ERIC values was observed after oxidation (compare bar 1 in each series of experiments), it is still unclear if the ERIC reduction can be attributed to the removal of detached ink particles from the oxidation process only. The same trend was observed for trials involving flotation followed by bleaching, except for trial at 100% TEMPO dosage. From these results, we cannot conclude that oxidation

by TEMPO is helping in the detachment of residual ink particles. Further investigations are required.

Bleaching of the pulp with peroxide

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DEINKED PULP also reduced ERIC values. The effect was observed for trials with and without TEMPO but was more important when TEMPO was added. It is possibly attributed to the combined effect of TEMPO and hydrogen peroxide. The effect of alkalinity previously discussed for strength properties could also be involved.

Although ERIC values were reduced after any treatments carried out on the deinked pulp as shown in Figure 7, the impact on brightness was not as straightforward as it was thought. Since brightness is dependent on both alkali darkening and residual ink concentration, it is obvious that the impact of alkali darkening had a stronger effect on brightness than the residual ink content.

Finally, to assess the effect of TEMPO, we must look at it as a whole, i.e. for the strength and optical properties achieavable.

TEMPO has shown significant improvement for strength properties but at the expense of brightness. However, it was possible to recover much of the brightness loss by adding a bleaching stage. It seems also that ink detachment is possible using TEMPO oxidizer. The effect must therefore be further studied to clearly establish if the phenomenon observed is real.

CONCLUSIONS

Oxidation of deinked pulps with TEMPO improved both strength and optical properties of handsheets. Breaking length, burst and the elastic modulus were significantly improved while tear was reduced.

The combination of TEMPO and peroxide seemed to boost strength properties.

The effects were approximately additive.

The flotation stage did not affect strength properties.

Oxidation with TEMPO reduced brightness. However, the brightness loss was more than recovered by adding a

peroxide bleaching stage after oxidation.

ERIC values were significantly reduced by oxidation and flotation. However, it was not possible to clearly determine if the oxidation stage by TEMPO was effective at detaching residual ink particles from the fibre surface.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge the Natural Sciences and Engineering Research Council of Canada (NSERC) and the Canada Research Chair in Valueadded Paper for their financial supports.

REFERENCES

1. Resource Information Systems, Inc., “North American Graphic Paper Forecast”, United States, p. 46, 2004.

2. Coulombe, G., Huot, J., Arseneault, J., Bauce, E., Bernard, J-T., Bouchard, A., Liboiron, M.A., Szaraz, G., Commission d’étude sur la gestion de la forêt publique québécoise, Mémoire presented to the Coulombe Commission, Ministère des ressources naturelles du Québec, Québec, December 2004.

3. Bouchard, J., Douek, M., The Effects of Recycling on the Chemical Properties of Pulps, 2nd Research Forum on Recycling, Ste-Adele, (5-7 oct. 1993).

4. Klofta, L., Miller, M.L., Effects of Deinking on the Recycle Potential of Papermaking Fibers, 2nd Research Forum on Recycling, Ste-Adele, (5-7 oct.

1993).

5. Howard, R.C., Bichard, W., The Basic Effect of Recycling on Pulp Properties, J. Pulp Paper Sci., 18(4):J151-J159 (1992).

6. Huber, P., Carré, B., Petit-Conil, B., Bhattacharjee, S., Effect of the Deinking Process on Physical Properties of Various Wood-Free Recovered Paper Furnishes, 7th Research Forum on Recycling, Quebec, (27-29 Sept. 2004).

7. Stack, K., Tria, J., Richardson, D., Ink Detachment and Redeposition in Alkali Flotation Deinking Systems, Appita 58 (4); 297-3001 (2005).

8. Dorris, G.M., Pagé, N., Natural and Accelerated Aging of Old Newspapers Printed with Black Mineral Oil Inks and Coloured Vegetable Oil Inks, 1: Deinkability, 5th Research Forum on Recycling, Ottawa, Canada, pp 43-53 (28-30 Sept. 1999).

9. Aspler, J., Sui, O., Zang, Y-H., Bonding Between Vegetable Oil Inks and Cellulose, TAGA Tech. Conf.

Proc., Paris, pp.894-914 (17-20 sept.1995).

10. Borchardt, J.K., Schroeder, T.J., Preventing Ink Over-dispersion Improves Old Newspaper Deinking Results, 88th Annual Meeting, PAPTAC, Montreal, pp. B139-B145, (22-31 Jan. 2002).

11. Ackermann, C., Göttsching, L., Quantitative Evaluation of Ink Particles in Deinking Pulp. Part I: Relationships Between Black Ink Particles and Optical Parameters of Deinked Pulp, Wochenblatt Für Papierfabrikation 5; 299-3005 (2002).

12. Hubbe, M.A., Rojas, O.J. and Venditti, R.A., Control of Tacky Deposits on Paper Machines – A Review, Nord. Pulp Paper Res. J., 21(2):154-171(2006).

13. Perrin, B., Julien Saint-Amand, F., Deinking Analysis Rejects in Newsprint and Copy Paper Mills, 12th PTS-CTP Deinking Symposium 2006, Paper 31, Leitzig, Germany, 2006.

14. Tahiri, C., Vignon, M.R. TEMPO-Oxidation of Cellulose: Synthesis and Characterisation of Polyglucuronans. Cellulose 2000, 7(2):177-188.

15. Kitaoka, T.; Isogai, A.; Onabe, F. Chemical Modification of Pulp Fibers by TEMPO-Mediated Oxidation, Nordic Pulp Paper Res. J., 1999, 14(4):279-284.

16. Isogai, A.; Saito, T.; Shibata, I.; Yanagisawa, M.; Kato, Y.; Magara, K.; Habu, N. TEMPO-Mediated Oxidation of Celluloses. Appita Annual Conference and Exibition Proc. 2005, Vol.2, pp. 237-241.

17. Le Roux, J., Daneault, C., Chabot, B., Acidic Groups in TMP Oxidized Fibres by TEMPO to Improve Paper Strength Properties, Pulp Paper Can., 107(4):39-41 (2006).

18. Barzyk, D., Page, D.H., Ragauskas, A., Acidic Group Topochemistry and Fibre-to-Fibre Specific Bond Strength, J. Pulp Paper Sci., 23(2):J59-J61 (1997).

19. Niskanen, K., Karenlampi, P., In Plane Tensile Properties, in Papermaking Science and Technology, Paper Physics, Vol. 5, Fapet Oy ed., Helsinki, Finland, pp.

139-143, 1998.

Résumé: Des suspensions de pâte désencrées ont été oxydées avec le TEMPO (radical 4-acé-

tamido-2,2,6,6-tetramethylpiperidine-1-oxyl), le bromure de sodium et l’hydroxyde de sodium sous diverses conditions expérimentales pour améliorer les propriétés optiques et mécaniques de la pâte. Les oxydations ont permis d’accroître significativement la rupture et l’éclatement alors que la déchirure a été diminuée. La blancheur de la pâte a été réduite à cause du jaunissement alcalin causé par les conditions alcalines du traitement. Toutefois, un blanchiment au peroxyde d’hydrogène suivant l’oxydation a permis de récupérer cette perte de blancheur.

Reference: Leroux, J., Daneault, C., Chabot, B., TEMPO-Mediated Oxidation to Improve Deinked Pulp Quality, Pulp & Paper Canada 111(1):T1–T5 (Jan/Feb 2010). Paper presented at the 93rd Annual Meeting of PAPTAC in Montreal, Que., February 5-9, 2007. Not to be reproduced without permission of PAPTAC. Manuscript received March 07, 2007. Revised manuscript approved for publication by the Review Panel 23 July 2009.

Keywords: DEINKED PULP, TEMPO, OXIDATION, STRENGTH PROPERTIES, OPTICAL PROPERTIES, BLEACHING.

For up-to-date industry news and events visit www.pulpandpapercanada.com 22

PULP & PAPER CANADA January/February 2010

pulpandpapercanada.com

DRYING

The Effect of Dryer Section Operation on the Linting Propensity of Newsprint

WINNER OF THE JASPER MARDON AWARD

By J.D. McDonald and M.V. Tchepel Abstract: The linting tendency of paper produced for offset printing can be significantly affected by the operation of the paper machine dryer section. Measurements on commercial paper machines have shown that, under certain conditions, the paper web will adhere to a dryer cylinder which will disrupt the paper surface, making it more susceptible to linting. Dryer surface temperature is a critical factor and improvements are possible on some paper machines by making simple modifications to dryer operation.

L

inting is a problem associated with the printing of uncoated papers and has been a particular concern for newsprint manufacturers since offset lithography became an important process for newspaper printing in the 1960s [1, 2]. Linting involves the removal of poorly bonded fibres from the paper surface in the nip of the printing press.

This material is either retained on the blanket or transferred to the plate, ink train, or fountain solution. If the build-up on the plate or blanket is significant, the material will interfere with the ink transfer of the printed image, and visual quality will deteriorate. Older offset presses may have to be stopped for manual cleaning of the blankets, which is a serious disruption to the production schedule. Newer presses may have automatic blanket washing systems, which still slow down the presses and can waste several hundred copies for each wash. In either case, competing newsprint suppliers are judged on the number of impressions that can be printed before a wash-up. It is critical for a paper manufacturer to be able measure the linting tendency of the sheet, understand the underlying mechanisms, and with this knowledge, find ways to reduce it.

A number of studies have shown that the linting propensity of paper can be affected by papermaking operations such as forming [1-6], pressing [1-3, 6-8], and calendering [1, 9-11].

However, there has been little attention given to the possible contribution of the dryers. This study indicates that the dryer section can be a significant contributor to linting, and that by applying simple and inexpensive solutions, the linting tendency of the paper can be reduced.

Factors that affect linting tendency

The majority of published work on the causes of linting has concentrated on pulp properties [12pulpandpapercanada.com

15]. Wood and Karnis [12] coined the name “linting candidate material” for wood particles with a specific surface area less than 2.5 m2/g. Their suggestions to reduce the proportion of linting candidate material were either to increase refining energy or increase the flow to the rejects refiner by increasing the centri-cleaner rejects.

A large portion of the linting material collected from modern printing presses consists of ray cells that have low specific surface area and poor bonding ability. Ray cells can be separated from the pulp using small diameter cleaners in the laboratory [16], but this would not be practical in commercial operation. Even in high concentrations, ray cells cannot be modified by mechanical action such as refining or ball-milling [17]. Only chemical treatment with peroxide was able to increase their tendency to bond within the paper sheet [17] by partial lignin removal [18] and surface oxidation.

In papermaking, the most effective strategy to reduce linting is to entangle and hold the ray cells that are located at the surface of the sheet with surrounding material. This means creating a consolidated, dense surface that is rich in fibrillar material. The sheet structure can be optimized during water removal in the forming and pressing sections by ensuring uniform water removal through both paper surfaces. Twin-wire formers [4-6] and highly-loaded, double-felted press nips [5, 6] give less linting than Fourdrinier paper machines and straight-through single-felted presses. By increasing the action of blades in the former [3] and by maximizing press section loads [3, 6] and sheet temperature [6] without crushing or disrupting the sheet [8], the paper surface is densified and thus, lowers the linting propensity.

The surface temperature of the first four to five dryers is critical, and sometimes their temperature is reduced to avoid picking [3]. Although calen-

J.D. MCDONALD formerly FPInnovations – Paprican, Pointe-Claire, Que.

M.V. TCHEPEL formerly FPInnovations – Paprican, Vancouver, B.C.

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DRYING dering consolidates the sheet, this tends to disrupt bonds in the sheet surface and can increase linting unless the calendering is done at high temperature [1, 9‑11].

EXPERIMENTAL

Measurement of linting tendency The linting tendency of paper is an elusive quality, and considerable effort has been expended to develop techniques that give reliable and reproducible measurement.

The existing methods — summarized in review papers [2, 19] — include sim‑ ple techniques that measure the surface strength of a small number of sheets [20, 21]; procedures that use laboratory proof presses; lint collection on small printing presses that simulate pressroom condi‑ tions [22‑24]; and full‑scale commercial printing trials [25, 26]. On‑line methods have been developed to measure the lint‑ ing propensity of pulp [27] and paper [28].

In the course of this study, three dif‑ ferent methods based on small printing presses were developed to measure the lint‑ ing tendency of paper. It is not the purpose of this paper to describe their operation in detail. From our experience, we have con‑ fidence in the values as a reliable indication of pressroom performance.

All of these lint testing methods use a conventional offset technique of applying the ink to the paper web from a rubber blanket surface. One of these, the Harris press method, utilizes a commercial unit printing on a web up to 30 inches wide.

After a standard length of web is printed, the lint is collected from the blanket. The amount of lint is determined gravimetri‑ cally, and the results are expressed as grams of lint deposited per square meter of the blanket surface after 20,000 impressions.

The other two methods, the Versatec and Apollo systems [22], provide a mea‑

sure of linting by the removal of blanket lint with transparent adhesive tape. The degree of linting is determined by visual comparison of the tape pulls against stan‑ dards.

Investigation of the factors causing linting

The first linting study was at a newsprint mill that had two sister machines, similar in most respects, fed from a common stock preparation area. One machine had a severe linting problem that had devel‑ oped over the previous year; the other was producing paper that was considered acceptable. Even though the machines received pulp from a common system, we followed “conventional” thinking about linting. We examined pulp characteristics, but could not find any significant problems that would affect one machine, but not the other.

Based on the assumption that there was a systematic difference between the two machines, we compared them. The most obvious difference was that the low linting machine had three presses with higher loadings, while the other machine had only two. During a trial on the prob‑ lem machine, the second press load was increased from 49 to 58 kN/m, which reduced the Apollo lint count from 16 to 10. Although this was a significant reduc‑ tion, it was still not possible to reduce the lint count to the value of about 7 produced by the sister machine.

There appeared to be a significant dif‑ ference between the two machines at the winders. It was thought that the spreader bar on the winder on the high linting machine might cause abrasion of the sheet.

Fig. 1. The linting tendency of paper—as measured with a small offset press— increases with the increase in the total drive current for the paper machine dryer section.

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Parent reels were interchanged between machines and winders, without effect on the inherent linting tendency of the paper.

Having eliminated the obvious factors, we decided to use statistical analysis to examine each machine in detail. Linting tendency had been measured on a regular basis over several years with the Har‑ ris press, and the stock preparation and machine operating data had been recorded as each test roll was being manufactured.

This information was analyzed by regres‑ sion techniques using linear, polynomial, and multi‑linear models. The only param‑ eter that indicated a statistically significant relationship with linting was the dryer sec‑ tion electrical drive load (Fig.1).

In essence, the linting tendency on the problem machine appeared to be directly related to the dryer section drive horse‑ power. The sister machine, which had a lower linting tendency, did not have a similar relationship. This result is prob‑ ably due to the fact that the changes in drive load were smaller on this machine, and therefore, the influence on linting is “hidden” by other machine parameters and experimental error. Note that in Fig. 1 the linting tendency did not show a significant increase until a drive load of 400 amps was exceeded, whereas the maximum load on the sister machine was in the range of 400 amps.

On discovering the dependence of lint‑ ing tendency on dryer drive horsepower, we initiated a program of opening dryer drums during machine shutdowns — sev‑ eral were found to be full of water. The increase in drive horsepower was the result of excessive water in a number of drums [29], and in some way, this appeared

Fig. 2. The operating dryer cylinder surface temperatures for a paper machine that produces paper with a high linting tendency. The ideal temperature profile to avoid linting is shown as a dashed line. The lower dryer surface temperatures are caused by: C – steam valve open or condensate shut; S – valves shut off; D – disconnected; B - broken siphon or carbon. pulpandpapercanada.com

PEER REVIEWED to have caused the linting tendency to increase. At first, because of speed changes as a result of gear backlash or dryer eccentricity, it was thought that abrasion was taking place on the dryer surface. However, precision speed measurements of the dryer surface with digital tachometers did not detect changes with drum rotation.

Temperature measurements were taken during normal operation on the dryer cylinder surfaces several feet within the sheet run with a digital thermocouplebased thermometer that was supported by an extendable rod and covered with Teflon tape to eliminate heating caused by friction. These measurements can also be done on-line using non-contacting infrared thermometers [30] or by measuring the dryer cylinder heads with a thermocouple-based thermometer, when the machine has been stopped for a shutdown [31]. We found that the surface temperature of the dryer cylinders in the “wet zone” was the important factor. This is illustrated in Fig.2, where the average measured surface temperatures of the dryer drums are shown for a machine with a high linting tendency. The temperature of flooded, disconnected, and shut-off dryers is lower. A “dryer horsepower – linting” relationship appeared in this study because the flooding affected both the dryer drive and the surface temperatures.

RESULTS AND DISCUSSION

Surface weakening of paper in the dryer section: possible mechanisms Linting results from the removal of unbonded or loosely bonded material on the paper surface during printing. Linting propensity could be increased if the paper surface was disrupted and weakened by adhesion to the surface of dryer cylinders.

There are two competing forces that control the behavior of fibrous material at the paper surface: the cohesive forces that bond surface material to the paper network and the force of adhesion to the dryer cylinder.

In the initial drying stage, free water is evaporated and hydrogen bonds are formed. The bond strength increases [32] as inter-fibre forces increase with waterremoval and the fibrous structures contract. However, low-specific-surface-area lint-candidate material — which consists of mainly ray cells and intact pieces of fibres between 10 and 100 microns in pulpandpapercanada.com

length [12] — is poorly bonded into the fibre network. The poor bonding ability is determined by the morphological shape and lignified surface — not by the chemical composition [5].

Factors that affect the adhesive force of paper to the dryer cylinder are: machine speed (that determines paper-cylinder contact time), paper moisture content, paper and cylinder temperatures, and furnish [33], as well as the composition of the cylinder surface [34]. The softening temperature of hemicellulose increases with decreasing moisture content [35, 36]. This trend is also applicable to hydrophobic lignin, but for mechanical pulps, only when moisture content is less than 4% [36, 37].

The following observations were made on pilot and production dryers when the paper leaves the cylinder [33]: • The temperature of the cylinder surface should be below the softening temperature of hemicellulose and lignin to prevent the adhesion.

• If the paper surface is wet, the softening temperature of hemicellulose is less than 100°C (approx. 50°C at the moisture content 20%; for lignin, it is 100°C [3537]) Then, the temperature of the dryer cylinder must be reduced below the softening temperature at the specific moisture content to prevent the adhesion.

• If the paper surface is dry on leaving the dryer cylinder, the softening temperature of hemicellulose and lignin is much higher than 100°C (aprox. 180°–220°C and 200°C respectively [35-37]). Then, the temperature of the cylinder will never exceed the softening temperature. Thus, paper will not adhere.

These observations have been confirmed by laboratory experiments for sheets containing sticky materials (stickies) [38].

To minimize adhesion for papers made from mechanical pulps, the temperature increase must be gradual in the initial drying cylinders so that the sheet temperature remains below the softening temperature of lignin and hemicellulose. Later, in the constant drying rate zone, moisture retreats from the paper surface which raises the softening temperature and with sufficient contact time and temperature, the surface will dry completely on leaving the cylinders. In this zone, the surface temperature of a critical number of dryers should be maintained at their maximum temperature of 100°C. When the paper

surface is dry, the paper will not adhere to the dryer because the softening temperature is greater than 100°C. In the open draw between cylinders, the moisture equilibrates throughout its thickness to rehydrate the surface. If the web encounters an unheated cylinder in the constant rate drying zone, the paper surface will be remoistened when it separates from the dryer, and the softening temperature will decrease sharply. If the dryer surface temperature is greater than the softening temperature, then the web will adhere to the dryer surface.

Ray cells and undeveloped fibre segments will cause discontinuities and weaknesses in the paper surface. Ray cells and fines with low specific surface will be especially vulnerable to disruption by this force because they have a lignified surface that is susceptible to sticking, and they are already weakly bonded into the fibre network. The most sensitive dryers are those near the wet end because at high moisture levels, the cohesive forces — that bond surface fibres to the paper network — are less than the force of adhesion of these fibres to the dryer cylinder.

The addition of hardwoods, such as aspen, to a softwood furnish would be expected to increase linting tendency because of the higher proportion of ray cells [37, 39] and a lower fibre length, as well as a different intrinsic lignin structure with a lower glass transition temperature [39]. Fibres at the paper surface that are remoistened in the open draw between dryer cylinders will be less conformable [40] and more prone to picking. This change in fibre conformability would be more pronounced for chemical pulp fibres than mechanical pulp fibres, except under specific conditions (temperature, furnish), when lignin degradation and mass loss in the mechanical pulp fibres lead to the creation of pores similar to those of chemical pulps [40] so that additional refining may be necessary.

Many newsprint mills use deinked pulps. This material could increase linting potential because of poor fibre conformability related to the loss of fibre swelling and fibre surface development. Fibre swelling and hence, conformability, can be restored by beating or refining [40]. Contaminants, such as stickies,in the recycled pulp, could also disrupt the fibre network, as well as act as adhesive in the dryer sec-

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DRYING tion, weakening the integrity of the sheet surface.

Eliminating linting problems through dryer modifications

Because some dryer sections have too much capacity, it is necessary to decide which dryer cans should be shut off. To develop criteria, we have applied the reasoning that as the moisture content of the web decreases, it becomes more difficult to alter its properties. This would explain the fact that higher press loadings [1-3, 6-8] and the use of steam showers [6, 41] reduce linting tendency. By lowering the moisture content of the sheet entering the dryers, the sheet becomes less susceptible to surface modification. This means that if dryers must be shut off or disconnected because of over capacity, they should be the ones nearest to the dry end. The design of the steam and condensate system must take this strategy into account.

The prescription for reducing the linting tendency by modifying the dryers can be reduced to a set of empirical rules: • Maintain siphons in top condition, • Maintain differential pressures that will ensure positive condensate evacuation from all drums, and, • Shut off or disconnect the drums near the dry end if the dryer section has too much capacity.

These procedures ensure that the drums carry a minimum of water and all dryer surfaces in the critical constant rate zone adjacent to the wet-end are sufficiently hot.

In Fig.3, the linting tendency of a paper machine, as measured by the Versatec Press, is plotted over a period of sev-

eral months. The reduction in linting took place because of the following changes: • Conversion from a three-stage to twostage cascade system in order to achieve sufficient pressure differentials, and • “Thermal alignment” of dryers so that all the “hot” dryers were towards the wet end, and the “cold” ones (shut-off or disconnected) were towards the dry end.

To make this change, a six-hour shutdown was required to install an equalizer pipeline between two condensate separators (Fig. 4). In addition, proper gauges were installed so that operators were aware of section steam pressure differentials.

Similar reductions in linting have been demonstrated in several other mills.

This report has focused on reducing linting by minimizing paper adhesion through a proper temperature profile in the early drying stages. There are a number of reasons for dryer cylinders to have a low surface temperature in this critical zone: siphons that are plugged, broken or that have improper clearance; closed or broken valves on either the steam or siphon lines; or low differential pressure [30]. Another strategy to reduce adhesion is by selection of dryer surface materials or coatings that minimize adhesion or pacification with chemical applications [42].

New dryer designs such as PapriDry [43] or OptiDry [44] can potentially reduce adhesion because their higher drying rates lead to dryer paper in the critical early drying stage and fewer release points.

CONCLUSIONS

We eliminated dryer section linting by following the common practice of lower-

Fig.3. The linting tendency of paper can be reduced by alignment of dryer cylinder temperatures. By modifying the steam and condensate system on the problem paper machine to correct the dryer temperature profile, the linting tendency of paper was reduced (◊—). The linting measurements from the sister paper machine are included for comparison (• - - -).

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PULP & PAPER CANADA January/February 2010

ing the temperature of the dryers in the “warm-up” zone [3] and keeping the temperature of the dryer surfaces at 100°C in the wet-end zone (approximately, dryers 6-15).

Measurements on commercial paper machines have shown that the linting tendency of newsprint can be significantly affected by the operation of the paper machine dryer section. Under certain conditions, the paper web will adhere to a dryer cylinder, which will disrupt the paper surface, making it more susceptible to linting in offset printing presses.

The critical factor that controls web adhesion in the dryer section is the softening temperature of hemicellulose and lignin, which depends on the moisture content of the web surface. The relationship between the moisture content and the temperature of the dryer cylinder will determine whether adhesion occurs. The softening temperature of other “sticky” materials, such as those that may be contained in deinked pulp, could influence this phenomenon. Therefore, the temperature profile of the dryers from the wet-end to the calender is a critical factor, particularly in the wet-zone where the paper surface is more susceptible to these disturbances. By making simple modifications to the dryer section to select the proper temperature profile, the linting tendency of offset paper can be significantly reduced.

ACKNOWLEDGMENTS

The authors would like to thank AbitibiBowater for permission to publish this report and former Abitibi-Price colleagues Bill Farrell and Nick Devich, who made

Fig. 4. Conversion from a 3-stage to 2-stage cascade system to allow better alignment of dryer cylinder temperatures. The conversion steps for 2-stage operation are: - Install new shut-off valve 1 and operate in shut off position - Operate control valve 2 in 100% open position, and - Install new cross-connection (A-B) and new manual valve 3 is 100% open. pulpandpapercanada.com

PEER REVIEWED major contributions to this study. The authors also thank Joe Aspler of FPInnovations-Paprican for his insightful comments.

REFERENCES

1. Ionides, G. The linting tendency of newsprint – A general review, Paperi ja Pu 66(4): 298, 301-302, 304306 (1984).

2. Aspler, J. Linting and surface contamination: Current status, 2003 Proceedings of the Technical Association of the Graphic Arts, Rochester, NY, 375-398 (2003).

3. Snider, E. Linting of offset newsprint, Pulp and Paper Can. 79(2): 51-53 (1978).

4. Hujala, J., and Ottelin, E. Improving paper quality for offset printing by twinwire units, Preprints of the 73rd Annual Meeting of the Technical Section, CPPA, Montreal, A207-A211 (1987).

5. Beaulieu, S., and Shallhorn, P. Strategies to minimize ray cell linting, 18th International Mechanical Pulping Conference 1993 Proceedings (Eucepa), p. 309-323 (1993).

6. Wood, J. R., McDonald, J. D., Ferry, P., Short, C. B., and Cronin, D.C., The effect of paper machine forming and pressing on offset linting, Pulp and Paper Can. 99 (10): 53-59 (1998).

7. Waech, T. G. Offset lint testing by image analysis, Pulp and Paper Can. 93(9): 63-65. (1992).

8. McDonald, J. D., Twitchen, D. A., Foulger, M. F., and Parisian, J. Improvement of printability of mechanical grades with precalendering, Pulp and Paper Can. 97(11): 50-55 (1996).

9. Crotogino, R. H. Temperature-gradient calendering, Tappi J. 65(10): 97-101 (1982).

10. Waech, T.G., Lint reduction by high temperature calendering, Proceedings of the 1990 Printing and Graphic Arts Conference, CPPA, Montreal, 105.

11. Gratton, M. F., Hamel, J., and McDonald, J. D. Temperature gradient calendering: From the laboratory to commercial reality, Pulp and Paper Can. 98(3): 62-70 (1997).

12. Wood, J. R., and Karnis, A. Towards a lint-free newsprint sheet, Paperi ja Puu 59(10): 660-662, 665668, 671-674 (1977).

13. Pere, J. Web-offset newsprint: evaluation of the effect of some raw material components upon printability and linting, Paperi ja Puu 60(9): 473-475, 477480 (1978).

14. Karttunen, S., and Lindqvist, H. Printability and linting of offset newsprint. Paperi ja Puu 61(2): 83-86, 89-97, 103. (1979).

15. Gichard, M., Shallhorn, P. M., and Karnis, A. Improving stone groundwood quality for offset printing, CPPA Annual Meeting, Montreal, Preprints 69: B185-B195 (1983).

16. Wood, J. R., Grondin, M., and Karnis, A. Characterization of mechanical pulp fines with a small hydrocyclone. Part I: The principle and nature of the separation, J. Pulp Paper Sci. 17(1): J1-J5 (1991).

17. Wood, J., Zhang, X., Chagaev, O., Stationwala, M., Goel, K., Shallhorn, P., and Beaulieu, S. The effect of

various mechanical and chemical treatments of ray cells on sheet properties and linting, Pulp Paper Can. 101(10): 83-87 (2000).

18. Tchepel, M. V., McDonald, J. D., and Dixon, T. The effect of peroxide bleaching on the mechanical properties of black spruce fibres, Proceedings of the PAPTAC 92nd Annual Meeting 2006; Book B, B193-B200; J. Pulp Paper Sci. 32(2): 100-104 (2006).

19. Mangin, P. J. A review of offset linting evaluation, 1987 Proceedings of the Technical Association of the Graphic Arts, Rochester, NY, 397-442 (1987).

20. Daniels, C. J. Measurement of offset printing contamination by paper, Tappi J. 59(3): 107-110 (1976).

21. Elphick, J. Measuring the linting characteristics and press performance of offset newsprint, TAPPI/ CPPA Fall Graphics Arts Conference, Toronto, 1-11 (1976).

22. Heintze, H. U., Rombough, W. C., and Gordon, R. W. Lint testing on a small web offset press, Preprints of CPPA Annual Meeting, Montreal 62: B229-B236 (1976).

23. Lebel, R. G., and Peterson, R. The web offset press operation and linting, Pulp and Paper Can. 81(12): 104-116 (1980).

24. Lindqvist, U, and Meinander, S. A pilot test for linting tendency of papers, Tappi J. 64(12): 61-63 (1981).

25. Heintze, H. U. The measurement of linting tendency in mechanical printing papers, Proceedings of the 1992 Printing and Graphics Arts Conference, CPPA, Montreal, 321-328 (1992).

26. Moller, K., Thomasson, B., Weidenmuller, J., Menzel, P., Walther, K., Falter, K.-A., Sporing, G., Miessner, M., and Axell, O. Factors influencing linting in offset printing of newsprint, Proceedings of the 49th APPITA Conference 115-121 (1995).

27. Amiri, R., Begin, B., Deshaies, S., and Mozaffari., S. Effects of wood and pulp quality on linting propensity, Pulp Paper Can. 105(6): 23-29 (2004).

28. Wood, J. R., Grondin, M., and Shallhorn, P. M. Evaluation of the MacMillan-Bloedel on-line lint test, Pulp Paper Can. 96(9): 60-65 (1995).

29. Concannon, M. D. Condensate effects on torque and horsepower in paper dryers, Tappi J. 63(9): 69-72

(1980).

30. Maggard, J. On-line measurement of dryer performance, Tappi J. 78(3): 264-265 (1994).

31. Ledbetter, C. J., and Hardee, J. Simple measurement technique proves successful in detecting flooded dryers, Tappi J. 77(5): 288-290 (1994).

32. Page, D. H., and Tydeman, P.A. Physical progresses during the drying phase, Consolidation of Paper Web, BP BIF Symposium, Cambridge, U.K. 371-392 (1965).

33.Meinecke, A., Huu, T. C.. and Loser, H. New concepts concerning paper drying with drying cylinders, Das Papier 42(10A): V159-165 (1988).

34. Pikulik, I. I., McDonald, J. D., and Aïtcin, P. C. The release of wet paper from novel press roll materials, Pulp Paper Can. 94(4): 46-51 (1993).

35. Goring, D. A. I. Thermal softening of lignin, Pulp and Paper Magazine of Canada 64(12): T517-T527 (1963).

36. Back, E. L., and Salmen N. L. Glass transitions of wood components hold implications for molding and pulping processes, Tappi J. 65 (7): 107-110 (1982).

37. Lewin, M., and Goldstein, I. S. Wood Structure and Composition, Marcel Dekker, New York, pp 193-4, (1991).

38. Fike, G. M., Merchant, T., and Banerjee, S. Simulation of the behaviour of stickie-contaminated sheets in a dryer section, Tappi J. 5(6): 28-32 (2006).

39. Sundholm, J. Mechanical Pulping, Fapet Oy, Helsinki, Finland, pp. 37-38 (1999).

40. Seth, R. The Difference Between Never-Dried and Dried Chemical Pulps, TAPPI Pulping Conference, 289-304 (2001).

41. McDiarmid, R. S. Steam shower applications on a paper machine. Appita 36(3): 226-230 (1982).

42. Thomas, G. S., and Griffin, E. R. The dryer section fights back, Pulp and Paper International 44(8): 30-32 (2002).

43. Pikulik, I. I. High intensity drying of paper. Pulp Paper Can. 95(3): 57-64 (1994).

44. Juppi, K. New impingement dryer OptiDry vertical, Revue ATIP 58(6): 22-26 (2004).

Resume: Il est possible de modifier substantiellement la tendance au peluchage du papier destiné à l’impression offset en apportant certaines améliorations au fonctionnement de la sécherie de la machine à papier. Des analyses de machines à papier commerciales ont démontré que, dans certaines conditions, la feuille de papier peut coller au cylindre sécheur, ce qui perturbe sensiblement la surface du papier et la rend plus susceptible au peluchage. La température de la surface des cylindres sécheurs est un facteur critique et certaines machines à papier peuvent être améliorées en apportant de légères modifications au fonctionnement de la sécherie.

Reference: McDonald, J.D, Tchepel, M.V. The Effect of Dryer Section Operation on the Linting Propensity of Newsprint. Pulp & Paper Canada 111(1): T6–T10 (Jan./Feb. 2010). Paper presented at the PAPTAC 95th Annual Meeting 2009 in Montreal, Que., February 3-4, 2009. Not to be reproduced without permission of PAPTAC. Manuscript received July 21, 2008. Revised manuscript approved for publication by the Review Panel Jan. 1, 2010. Jasper Mardon Memorial Award 2009.

Keywords: TEMPERATURE; SPECIFIC SURFACE; ADHESION; COHESION; LIGNIN; HEMICELLULOSES; REFINING; BEATING; SOLIDS; MACROSTICKIES

letters editor TO THE

cindy@pulpandpapercanada.com pulpandpapercanada.com

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Surface Characterization and Surface Modification of Mechanical Pulp Fibres

By K. Li, X. Lei, L. Lu, and C. Camm Abstract: The surface of thermomechanical pulp (TMP) and chemi-thermomechanical pulp (CTMP) fibres was characterized with scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atomic force microscopy (AFM). A large amount of lignin-rich surface material was found on the surface of CTMP fibres, which indicates that fibre separation took place in the middle lamella region. A surface peeling method was used with a PFI mill to remove the surface material of BCTMP fibres. Results show that the interfibre bond strength increased by 32% after surface peeling. White-rot fungus and xylanase were also used to modify the fibre surface of CTMP. The preliminary results show that both of them can improve the interfibre bonding of the CTMP fibres.

M

echanical pulps such as thermomechanical pulp (TMP) and bleached chemi-thermomechanical pulp (BCTMP) have been used increasingly in higher grade paper. BCTMP is now used in wood-free printing and writing paper grades and multiple coated folding board grades.

This is mainly due to the high bulk and high opacity of BCTMP [1,2]. Faced with challenges from electronic media, many traditional newsprint producers are upgrading their TMP to produce supercalendered (SC) paper. The major disadvantage of mechanical pulp is its low physical strength.

Physical strength is important not only for the end use of paper, but also for the runnability on paper machines. When the amount of BCTMP added in wood-free paper furnish exceeds a certain level, web breakage occurs more frequently due to lowered wet web strength. Low bonding strength also causes delamination between the middle ply and the top on the bottom ply of multiple boards. In the case of TMP produced for SC paper production, fibres are extensively delaminated or damaged to achieve a very low freeness (CSF) level, below 100 ml. More expensive kraft pulp (KP) has to be added in the furnish to reinforce the paper strength, improving especially the paper machine runnability. Surface roughening is another major issue in using mechanical pulps for certain paper grades. It has been found [3,4] that one of the major causes of surface roughening is de-bonding between fibres. When inter-fibre bonding is weak, de-bonding can easily occur when paper is rewetted.

Inter-fibre bonding strength is one of the major factors in determining paper strength [5].

Although fibre flexibility and fibre collapsibility 28

PULP & PAPER CANADA January/February 2010

are very important in inter-fibre bonding, they mainly determine the bonded area between two fibres. The specific bonding strength (SBS) is determined mainly by the fibre surface, since the bonding takes place only between the surfaces of the fibres. Therefore, the morphology and the chemistry of fibre surface play a crucially important role in inter-fibre bonding.

In our previous studies [6,7] and studies by others [8,9], it has been found that lignin is highly concentrated on the surface of kraft pulp fibres. It has also been found [10,11] that a large amount of lignin-rich material is present on the surface of mechanical pulp fibres. We further studied the effect of fibre surface lignin on inter-fibre bonding and found that for both kraft pulp and CTMP fibres, high surface lignin hampers interfibre bonding [12]. This is in agreement with the theory about inter-fibre hydrogen bonding. Since lignin is much more hydrophobic than cellulose, the presence of lignin on the fibre surface will not contribute much to inter-fibre hydrogen bonding, but block the hydrogen bonding that may form between cellulose chains on the two adjacent fibre surfaces.

In commercial BCTMP production, the interfibre bonding strength of pulp is adjusted in the bleaching stage by changing the NaOH dosage.

A higher dosage of NaOH increases the physical strength of pulp dramatically; however, the bulk of the pulp at the same time is lowered. In our previous studies [6,12], we have developed an experimental method to remove the lignin-rich surface material of CTMP fibres in order to compare the effect of surface lignin on inter-fibre bonding.

It was found that by removing the fibre surface material, the inter-fibre bonding strength of the

K. LI Dept. of Chemical Engineering & Limerick Pulp and Paper Research and Education Centre, Univ. of New Brunswick, Fredericton, N.B. X. LEI Dept. of Chemical Engineering & Limerick Pulp and Paper Research and Education Centre, Univ. of New Brunswick, Fredericton, N.B., and State Key Laboratory of Pulp and Paper, South China University of Technology, Guangzhou, China L. LU State Key Laboratory of Pulp and Paper, South China University of Technology, Guangzhou, China

C. CAMM Dept. of Chemical Engineering & Limerick Pulp and Paper Research and Education Centre, Univ. of New Brunswick, Fredericton, N.B. pulpandpapercanada.com

PEER REVIEWED CTMP fibres was increased by about 40%.

Encouraged by this result, we tried this method on BCTMP fibres in the present study. We tried to use fungi and enzymes to modify the surface of mechanical pulp fibres. Use of fungi to treat wood chips for energy saving in refining has been reported extensively [13,14]. The general conclusion is that the fungal treatment saves energy and, in most cases, improves pulp strength. However, this technology has not been used in commercial production due mainly to the fact that bio-treatment would complicate the existing mechanical pulping process. This paper discusses the surface characteristics of the mechanical pulp fibres and potential technologies for removing the lignin-rich fibre surface material to improve inter-fibre bonding with a mechanical peeling method and bio-surface modification methods.

EXPERIMENTAL

Pulp Samples Aspen CTMP and BCTMP, spruce TMP and KP were obtained from Canadian pulp and paper mills.

PFI Mill Operation A PFI mill was used for peeling off the surface material of aspen BCTMP fibres.

Pulp consistency used was 30% instead of TAPPI standard refining consistency of 10%. Bar-bar clearance was adjusted to 0.35 mm and the standard weight (pressure) applied to the roll was removed.

Under these conditions, the abrasive and surface peeling actions are expected to prevail in the refining process.

Internal Bond Strength (IBS) The internal bond strength (IBS) of sample sheets was tested with a monitor/ internal bond test station manufactured

by TMI Test Machines Inc. according to TAPPI standards. Samples for the testing were prepared on the I-Bond Sample Prep Station accompanying the internal bond testing station.

Fungal Treatment of CTMP Pulp Eucalyptus Urophylla CTMP was obtained from the Chinese Academy of Forestry, China. The brightness of the unbleached pulp was 49.6% ISO, and the freeness was 700 ml. The pulp was air-dried to a moisture content of 15% and stored at 4°C until used. The white-rot fungus T.h. 19-6 pulpandpapercanada.com

was isolated from bamboo by the State Key Laboratory of Pulp and Paper Engineering, South China University of Technology, Guangzhou, China. This fungus produces manganese peroxidase, laccase, hemicellulase and a minor portion of cellulose [15]. The fungal strain was cultured on PDA bevel culture medium, and a spore suspension of 5-day-old cultures was used as the inoculum. Seeding of the pulp was carried out with 0.5 ml/g pulp (o. d.).

The incubation was performed in 1000 ml flasks with 30 g of the CTMP pulp (o.d.), 15 ml of spore suspension, and some of the culture medium, without using a buffer. Sterilized water was added to give a final pulp consistency of 25% (w/v). The solution, flask, and pulp samples were sterilized in an autoclave (30 min, 121°C).

The control samples used sterile water instead of the spore suspension. The flask was incubated in a stationary culture condition for 5 days at 28°C, and at an initial pH of 4.5. The flasks were flushed with oxygen every day. After incubation, all pulp samples were filtered with a 400 mesh nylon screen and washed with distilled water to remove the superficial mycelidium and then dried in air.

Enzymatic Treatment of Wood Chips for CTMP Wood chips of four years old eucalyptus chips were prepared and put in plastic bags to balance moisture content. Pulpzyme HC was provided by Novo-Nordisk Corporation. This commercial enzyme is derived from a selected strain of bacterial origin, produced by submerged fermentation of a selected strain of Bacillus, and has a specificity of catalyzing the hydrolysis of deacetylated xylan substrates. It contains endo-1, 4-ß-D xylanase activity (EC 3.2.1.8) and is virtually free of cellulose activity. Pulpzyme HC has an activity of 1000 AXU/g (xylanase units).

Xylanase treatments were carried out at 40-65°C and at liquor-to-wood ratio of 6/1 (w/w). The pH was initially adjusted with a 1N H2SO4 solution. The control CTMP was treated in the same way without xylanase charge. The Pulpzyme HC dosage, ranging from 0 to 50 AXU/g of oven dry chip weight, and treatment time, varying from 0-4 hrs, were determined.

Detailed steps of the experiment were as follows.

The chemical treatment of wood chips

was performed with washed eucalyptus chips using a liquor-to-wood ratio of 4:1 in a rotary digester with capacity of 1.5 L, and a charge of 2% NaOH and 10% Na2SO3.

The heating time was 1 hr from 24°C to 120°C, and the cooking time at the maximum temperature was 30 min. After that, three-stage refining was performed in a refiner (ZSP-300) under the conditions: 20-25% consistency, and bar clearance of 0.50 mm, 0.30 mm, and 0.15 mm, respectively.

Scanning Electron Microscope (SEM) SEM images of pulp fibres were obtained using a JEOL JSM-6400 scanning electron microscope, operated in secondary electron mode at an accelerating voltage of 10 kv. CTMP fibre samples were dehydrated with an ethanol dehydration series and then dried with critical point drying method. The fibre surfaces were coated with gold for 120 s using a S150 sputter coater prior to scanning.

Transmission Electron Microscope (TEM) TEM images of pulp fibres were obtained using a JEOL 2011 transmission electron microscope, operated at 120 kv. Images were taken with a Gatan digital camera.

The fibre samples were dehydrated with an ethanol dehydration series and then embedded in Spurr-resin. Ultra thin sections (70 nm) were cut with a diamond knife onto distilled water. Sections were collected onto uncoated, copper grids.

Some grids with sections were post-stained with uranyl acetate and lead citrate to enhance contrast.

AFM Observation AFM were performed with a Asylum MFP-3DTM stand-alone atomic force microscope, combined with a MultiMode AFM head and J-type scanner. Dual height and phase images were captured with AFM tapping mode in air environment using commercial Si tetrahedral tip mounted on a rectangle-shaped cantilever.

Cantilever length is 160 µm, width 50 µm, spring constant 42 N/m, and resonance frequency about 300 kHz. The tip radius is smaller than 10 nm. Free amplitude (A0) of about 25 nm and moderate tapping with a set-point amplitude ratio (rsp) between 0.4-0.6 were used, and the AFM was operated in air.

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a

b

c Fig.1. SEM images of a spruce KP fibre (a), aspen BCTMP fibres (b,c), and spruce TMP fibres (d,e).

Table I. The inter-fibre bond strength (IBS) of BCTMP fibres after surface peeling.

BCTMP CTMP*

d

e

RESULTS AND DISCUSSION

Fibre Surface Characterization Surface morphology of mechanical pulp fibres differs completely from that of bleached kraft pulp (BKP), as shown in Fig. 1. The BKP fibre shows clear microfibril pattern on the surface since almost all lignin has been removed from the pulp fibres. On the surface of CTMP fibres, a large piece of non-fibrillar material can be seen. In our previous study [10], it was found that the non-fibrillar patches are middle lamella material remaining on the fibre surface. This indicates that fibre separation at these particular locations occurred mainly in the middle lamella region. There is much less non-fibrillar material on the surface of TMP fibres, but a large amount of small particles can be seen. These small particles can be the ground large pieces of middle lamella or the ground flake-like fines that re-deposit on the fibre surface.

Melted lignin was also observed on the TMP fibre surface appearing like a smooth coating layer (Fig. 1e).

With AFM, fibre surface was observed with much higher resolution (Fig. 2).

Nano-scale microfibrils can be observed on the surface of KP, BCTMP and TMP fibres. Without lignin as matrix material, microfibrils of 20-40 nm in diameter 30

were clearly identified on the surface of kraft fibres. In contrast, the microfibrils on the CTMP fibres, although distinguishable, appear blurry. In addition, the non-fibrillar patches, as observed with SEM, appear as large granules on the fibre surface. The granular-shaped lignin on the fibre surface was also observed by others [16,17]. In the case of TMP, the microfibrillar structure is clearer than the BCTMP, which indicates that in the TMP refining process, more fibre separation occurred in the secondary wall, so less lignin-rich material from middle lamella covers the fibre surface.

It is apparent that a large amount of lignin-rich material is present on the surfaces of both BCTMP and TMP fibres.

This material will not only form a physical barrier to inter-fibre bonding, it will also hinder the inter-fibre hydrogen bonding due to the hydrophobicity nature of lignin.

Fibre Surface Modification with a Mechanical Peeling Method It can be seen from the SEM image of BCTMP fibres (Fig. 1), that the nonfibrillar patches on the fibre surface are not structurally integrated with the main body of the fibre but located on the outermost layer of the fibre. As in both conventional

PULP & PAPER CANADA January/February 2010

Original (J/m2)

After surface peeling (J/m2)

51.2 16.3

68.3 22.71

* Reference [12].

chip refining and low-consistency (LC) pulp refining, the outer layers of fibre can be peeled off by refining actions, along with other refining effects such as fibre shortening and internal and external fibrillation, it is expected that if appropriate refining conditions are chosen, the peeling effect of refining can be emphasized so the lignin-rich surface material of the BCTMP fibres can be removed without much alteration of the main fibre body as shown in Fig. 3.

In our previous studies [6,12], we developed a surface peeling method by using a PFI for removing surface material of CTMP fibres for experimental purposes. In the present study the same method was used to remove the lignin-rich surface material of BCTMP fibres. It can be seen from Table I, that after the surface peeling process, the inter-fibre bond strength was increased by 32%. This is interesting since it indicates that it is possible to modify or develop new technologies in refining process to significantly improve the inter-fibre bonding strength of BCTMP fibres. This may be incorporated in the last stage of the CTMP refiner or in the LC refining of BCTMP prior to the paper machine.

Furthermore, if the surface peeling process is conducted on the CTMP fibres before pulpandpapercanada.com

PEER REVIEWED

a

b

c

d

e

f

Fig. 2. AFM images of spruce KP fibres (a,b), aspen BCTMP fibres (c.d), and spruce TMP fibres (e,f).

bleaching, the removal of lignin-rich material may also reduce the chemical demand in the subsequent bleaching process.

Fibre Surface Modification with Bio-treatment A number of studies have found that treating wood chips with white-rot fungi prior to refining can save refining energy and improve pulp quality. However, fungal treatment of wood chips takes too long (2-3 weeks), and it is not quite compatible with the existing mechanical pulping process. In our previous studies [15,18], we tried to use a white-rot fungus to treat CTMP fibres for improving pulp strength and saving energy in LC refining of the BCTMP. It was found that the fungal treatment opened up the fibre wall structure, and hence, in the subsequent LC refining, much less energy was required, and better pulp quality was obtained. It can be seen from Fig. 4 that before fungal treatment, the middle lamella remains on the surface of CTMP fibres, appearing dark. After fungal treatment, the dark middle lamella material disappeared. This is expected since the fungus attacks mainly lignin. This will contribute to the increased inter-fibre bonding between fibres. The pulpandpapercanada.com

rationale behind this fungal treatment was that if fibres are treated by fungi, and the fungal actions can be limited on the fibre surface only, the fungal treatment time can be significantly reduced. This will make it possible to apply the fungal treatment technologies to the mechanical pulping process. More detailed work is needed to develop applicable technologies in this regard.

Studies on enzyme application in mechanical pulping are emerging [19,20].

Enzymes are much easier to use and are more specific to targeted wood components than fungi. In this study, we used xylanase to treat wood chips prior to a CTMP process. The preliminary results (Fig. 5) show that after xylanase treatment of wood chips, fibre separation occurs more between the S1 and S2 layers. The cracks between S1 and S2 (appearing bright) are quite apparent. In contrast, without xylanase treatment, the cracks occur more in the middle lamella region. Xylanase hydrolyzes only xylan in wood. When xylan in the secondary wall is removed or degraded, the fibre wall structure will be opened up at the particular points, and in the subsequent refining process more fibre separation will take place along the weakened points. The

impact of fibre separation on fibre surface property is that when fibre separation takes place in secondary wall, the surface of the resultant fibres will expose more cellulose fibrils, which is beneficial to inter-fibre bonding. In comparison, when fibre separation takes place in middle lamella region, more lignin-rich middle lamella material will cover the fibre surface.

Furthermore, if fibre separation takes place in the secondary wall, less energy would be required for fibre development in the secondary stage refining. In the development of mechanical pulping technology, it was expected that TMP and CTMP would save refining energy by softening the middle lamella material and thus making fibre separation easier. However, it turned out that although energy is saved in the fibre separation in the primary refiner stage, more energy is consumed in the secondary stage for fibre development [21,22]. By targeting hemicellulose in the secondary wall with xylanase, fibre separation can take place in the secondary wall region. This will generate fibres with S1 layer exposed on the surface. More importantly, when fibre separation takes place in the secondary wall, fibres produced are already well developed, so much less refin-

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Fig. 3. Aspen BCTMP fibres after surface peeling. a

b

Fig. 4. Eucalyptus CTMP fibres before (a), and after (b) fungal treatment.

a

b

c

Fig. 5. Fibre separation in refining without (a,b), and with (c) xylanase treatment of eucalyptus wood chips

ing is required in the secondary refining stage. This is the reason that the overall refining energy is expected to be lower.

Therefore, enzyme treatment as such in mechanical pulping may open a new venue to energy saving and pulp quality improvement for the mechanical pulping process.

Further research in this area is ongoing in our laboratory.

CONCLUSIONS

Mechanical pulp fibres retain almost all lignin from wood, which contributes to their high yield and high bulk properties.

A large amount of lignin-rich material is also present on the surface of mechanical pulp fibres. The hydrophobic lignin-rich material is one of the major reasons for low inter-fibre bonding strength of mechanical pulp fibres.

Lignin has to be retained in the mechanical pulp to maintain the high yield and high bulk of mechanical pulp.

Adjusting the bonding strength of BCTMP fibres in bleaching by using more 32

NaOH improves inter-fibre bonding strength, but at the same time decreases the bulk of BCTMP. Removing specifically the lignin-rich material on the fibre surface will not lose much yield and bulk but will substantially increase the inter-fibre bonding. Targeting surface lignin only with a mechanical peeling or bio-treatment of pulp provides an alternative to improve the bonding ability of mechanical pulp fibres.

Enzyme treatment of wood chips can open up the cell wall structure, and hence, lead to fibre separation at preferable locations in subsequent refining.

When more fibre separation takes place in the secondary wall, more cellulose fibrils will be exposed on the fibre surface, which benefits inter-fibre bonding. More importantly, enzyme treatment of wood chips or coarse fibres in mechanical pulping may lead to significant energy saving in refining.

More research should be carried out in this direction to develop applicable tech-

PULP & PAPER CANADA January/February 2010

nology for the mechanical pulping process.

ACKNOWLEDGEMENTS

The authors would like to acknowledge the financial support of NSERC, CFI, NBIF, AIF to this project.

LITERATURE

1. Zhou, Y., Proceedings of PAPTAC 90th Annual Meeting, 2004, B1429, Montreal, Canada.

2. Xu, E.; Sabourin, M.J.; Cort, J.B., Tappi J., 82(12): 75-82 (1999).

3. Karnis, A., J. Pulp Paper Sci., 21(9): J321-329 (1995).

4. Forseth, T.; Wiik, K.; Helle, T., Nordic Pulp Paper Res. J., 12(1): 67-71 (1997).

5. Page, D.H., Tappi J., 52(4): 674-681 (1969).

6. Li, K.; Reeve, D.W., J. Pulp Paper Sci., 28(11): 369373 (2002).

7. Li, K.; Reeve, D.W., Cellulose Chem. Technol., 38(3-4): 197-210 (2004).

8. Fardim P.; Durán N., Colloids and Surfaces A: Physicochem. Eng. Aspects, 223: 263-276 (2003).

9. Dorris, G.M.; Gray, D.G., Cellulose Chem. Technol., 12: 721-734 (1978).

10. Li, K.; Tan, X.; Yan, D., Surface and Interface Analysis, 38: 1328-1335 (2006).

11. Cisneros, H.A.; Williams, G.J.; Hatton, J.V., J. Pulp Paper Sci., 21(5): J178-J184.

12. Shao, Z.; Li, K., J. Wood Chem. Tech., 26(3): 231244 (2006).

13. Akhtar, M.; Blanchette, R.A.; Kirk, T.K., Advances in Biochemical Engineering/ Biotechnology, 57: 160-195 (1997).

14. Eriksson, K.E., Tappi J., 68(7): 46-55 (1985).

pulpandpapercanada.com

PEER REVIEWED 15. Yang, Q.; Zhan, H.; Wang, S.; Fu, S.; Li, K., Bioresources, 2(4): 682-692 (2007).

16. Gustafsson, J.; Lehto, J.H.; Tienvieri, T.; Ciovica, L.; Peltonen, J., Colloids and Surfaces A: Physicochem.

Eng. Aspects, 225: 95-104 (2003).

17. Xu, Y.; Li, K.; Zhang, M., Colloids and Surfaces A: Physicochem. Eng. Aspects, 301, 255-263 (2007).

18. Yang, Q.; Zhan, H.; Wang, S.; Fu, S.; Li, K., Bioresources Technology, 99: 8118-8124 (2008).

19. Richardson, J.D.; Wong, K.K.Y.; Clark, T.A., J. Pulp Paper Sci., 24(4): 125-129 (1998).

20. Pere, J.; Siika-Aho, M.; Viikari, L., Tappi J., 83(5): 1-8 (2000).

21. Karnis, A., International Mechanical Pulping Conference, EUCEPA, June 15-17, 1993, 268-289, Oslo, Norway.

22. Kurdin, J., Paper Trade Journal, 163(I) 6/15: 23-27 (1979).

Resume: Nous avons caractérisé la surface des fibres de pâte thermomécanique (PTM) et de pâte chimico-thermomécanique (PCTM) à l’aide de la microscopie électronique à balayage (MEB), de la microscopie électronique à transmission (MET), et de la microscopie à force atomique (AFM).

Nous avons trouvé à la surface des fibres de PCTM une grande quantité de matière riche en lignine, ce qui indique que les fibres se sont séparées dans la région de la lamelle mitoyenne. Nous avons employé une méthode de décollement de la surface avec un raffineur PFI, afin d’enlever la matière à la surface des fibres de CTMP blanchie. Les résultats indiquent que la résistance des fibres à la cohésion a augmenté de 32 % après le décollement de la surface. Nous avons utilisé un champignon responsable de la carie blanche et de la xylanase et modifié la surface de la fibre de PCTM. Les résultats préliminaires indiquent que ces deux produits peuvent améliorer la cohésion interne des fibres de PCTM.

Reference: Li, K., Lei, K., Lu, L., Camm, C. Surface Characterization and Surface Modification of Mechanical Pulp Fibres. Pulp & Paper Canada 111(1): T11–T16 (Jan./Feb. 2010). Paper presented at the 2008 PACWEST Conference in Jasper, AB, Canada, June 18-21, 2008. Not to be reproduced without permission of PAPTAC. Manuscript received April 01, 2008. Revised manuscript approved for publication by the Review Panel February 27, 2009.

Keywords: TMP; BCTMP; FIBRE SURFACE; SURFACE MODIFICATION; FUNGI; ENZYME.

International Chemical Recovery Conference March 29 – April 1, 2010 Williamsburg Lodge, Williamsburg, VA www.icrcmeeting.org

Smallwood 2010 – Bridges, Business and Biomass April 20-22, 2010 Hot Springs, Arkansas Forest Products Society, 608-231-1361, www.smallwoodconference.org

International Biomass Conference & Expo May 4-6, 2010 Minneapolis, MN www.biomassconference.com

TAPPI-PIMA PaperCon 2010 Conference & Trade Fair May 2-5, 2010 Atlanta, GA 800-446-943, memberconnection@ tappi.org, www.tappi.org

World Bioenergy 2010 May 25-27, 2010 Jönköping, Sweden www.elmia.se/en/WorldBioenergy/

PAPTAC Finishing, Warehousing & Shipping Annual Conference May 26-27, 2010 Quebec, Que. Jean-Marie Methot, Methot.j@ videotron.ca; www.paptac.ca

Progress in Paper Physics Seminar June 7-10, 2010 Montreal, Que. Norayr Gurnagul, 514-630-4101, ex 2241, Norayr.gurnagul@fpinnovations.ca, www.paprican.ca

PacWest Conference June 9-12, 2010 Kamloops, B.C. Mary Barnes, barnesmm@shaw.ca; www.pacwestcon.net

Zellcheming Annual General Meeting & Expo June 29-July 01, 2010 Wiesbaden, Germany zellcheming@zellcheming.de, www.zellcheming.com

China Paper Shanghai Sept. 15-17, 2010 Shanghai, China www.chinapaperexpo.com

Control Systems 2010 Sept. 15-17, 2010 Stockholm, Sweden SPCI & Innventia, www.controlsystems2010.com

Events

Send events info and news announcements to media@pulpandpapercanada.com pulpandpapercanada.com

January/February 2010 PULP & PAPER CANADA

33

T16

TECHNOLOGY NEWS Press felt centering with UltraEdge improves press operation UltraEdge is Metso’s new non-contacting fabric edge tracking solution, providing precision and reliability in fabric control on paper and board machines. Problems with fabric control have direct financial effects, such as loss of felts or dryer fabrics and machine downtime needed to replace them.

UltraEdge provides accurate felt width and shrinkage behavior information during production. When UltraEdge units are installed on both the tending and drive side of the machine, the felt width data can be obtained and the felt can be centered automatically. Centering the felt typically improves runnability in the edge areas due to symmetric felt wear. Start-ups get faster, which improves

First curtain coater used in carton board machine

After many years of intensive development, Voith Paper has won the first order for a curtain coater used for graphic paper coating in a board machine. This innovative process is being used for the first time for coating applications beyond the field of specialty papers where the curtain coater has been successfully used for years to apply thermo-reactive or capsule coatings.

This new process provides good coverage and superior printability, as well as optimal runnability and significant energy savings.

In this rebuild project, the existing air knife coater was replaced with a curtain coater, allowing the company to overcome the current speed limit and to substantially increase the coating solids content. In this particular case, the coat drying energy costs will almost be halved.

In addition, curtain coating ensures optimal coverage, permitting the use of more cost-effective coating pigments.

The operating window of the curtain coater was successfully widened thanks to efficient process development in the Voith Paper PTC. Voith Paper 613-632-4163 www.voithpaper.com

34

machine efficiency. UltraEdge is an excellent tool for troubleshooting the root cause of problems thanks to the felt width data and accurate felt edge positioning in connection with felt damage, for example.

The operation of UltraEdge is based on ultrasound technology, which eliminates all tracking-related abrasion and wear at the fabric edges. The sensor transmits high-frequency ultrasonic sound bursts, with which the distance of the fabric edge from the sensor can be calculated. Compared to other optical fabric positioning solutions, fabric color and composition have no effect on measurement.

UltraEdge is designed for both press and dryer section fabric control on all paper and board machines. It can be used for edge tracking with both pneumatic and electromechanical guides. The dryer section application is designed for the challenging dryer hood conditions.

Metso 514-335-5426, www.metso.com

Good things come in small packages.

To inquire about advertising in Pulp & Paper Canada contact

Jim Bussiere 800-268-7742, ext 3606 or 416-442-5600, ext 3606 Fax: 416-510-5140

Equipment Roll cover enhances sheet dryness for tissue

SchaeferRolls, Inc. has just completed an expansion of its North American industrial roll cover facility in Farmington, NH. The expansion included the installation of a large Farrell roll grinder, new composite and polyurethane casting and curing systems, upgraded vulcanizing controls, upgrading of a precision balancer, and other key capital equipment associated with quality and cost effective production.

SchaeferRolls’ unique cover products include its HybriFlex dual layer cover which provides high open area benefits for improved sheet dryness, energy savings, and improved quality for tissue production. SchaeferRolls has more than 20 operating installations of its HybriFlex covers on tissue machines, with new installations in North America due to start up in early 2010.

In addition, SchaeferRolls now has the ability to produce its C2 cover for extended service life on composite covered cotton filled calender rolls.

SchaeferRolls has built more than 200 C2 covers bonded to cotton filled rolls in various calendering applications.

SchaeferRolls Inc. 603-335-1786, www.schaeferrolls.com

PULP & PAPER CANADA January/February 2010

pulpandpapercanada.com

Professional Connections Careers

Equipment

PulP & PaPer Jobs Freeman Staffing, Inc. specializes in the placement of engineers (all disciplines), production type supervisors, managers, mill and/or plant managers and corporate executives in the pulp & paper industry, North America-wide. For specific current job searches call us or contact our web site. All resumes are treated with complete confidentiality.

Freeman Staffing, Inc.

(800) 221-9629 or FAX (360) 653-8271 email: markp@freemanstaffing.com

web site: www.freemanstaffing.com

Consultants Engineering services for the pulp and paper industry

Telephone 416. 391. 2322 E-mail mail@dickeng.com Web site www.dickeng.com

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PHOENIX Process Equipment Co. www.dewater.com (502) 499-6198

VINCENT CORP. SCREW PRESS Clarifier Sludge Knots & Shives Screen Rejects Stock Thickening Recycle Rejects Black Liquor

Global Know-how and Local Service for the Forest Industry Pöyry (Montreal) Inc. Montreal, QC 514 341 3221

Pöyry Forest Industry Consulting Inc. Tarrytown, NY Montreal, QC 914 332 4000 514 845 8715

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Engineering balanced sustainability for a complex world. www.poyry.ca

pulpandpapercanada.com

FREE ON-SITE DEMOS www.vincentcorp.com (813) 248-2650 Fax: (813) 247-7557

January/February 2010 PULP & PAPER CANADA

35

TECHNOLOGY NEWS

Total solution for measuring Kappa number and brightness of wet pulp ASD Inc. introduces the QualitySpec® K-B Sample Press to complement the QualitySpec K-B NIR Analyzer released last year. Together, the NIR analyzer and the Sample Press comprise a total solution for simultaneous at-line measurement of Kappa number and brightness on wet pulp. The sample press replaces timely and labour-intensive methods with an automated press that eliminates operator-to-operator variability in sample quality. This ultimately provides for tighter, more accurate process control, and the ability to feed forward and feed back information on Kappa number and brightness.

“With the QualitySpec K-B and Sample Press system, the pulp and paper industry has an improved process optimization solution allowing for increased frequency of in-process

measurements, and greatly reduced need for wet chemistry and the corresponding consumable toxic chemicals,” says Chris Pederson, ASD technical specialist for pulp and paper applications. “More frequent testing drastically reduces the consumption of delignification and bleaching chemicals and waste, and product consistency is maximized, potentially saving each mill hundreds of thousands of dollars annually.”

ASD collaborates with industrial professionals, analytical researchers, and remote sensing scientists to provide reliable, high performance analytical instrumentation.

ASD Inc. 303-444-6522, www.asdi.com.

E-Flex – the new cost saver in press dewatering With Voith Paper’s E-Flex fabrics, a breakthrough has been achieved in the design structure of press fabrics. Paper mills which installed E-Flex achieved fast machine start-ups, higher nip dewatering values, and better paper quality.

It’s a matter of structurally optimized fabrics that influence fabric characteristics through targeted placement of polymer particles. The pressure transmission in the nip is homogenized. In addition, the polymer structure provides improved resilience of the press fabric and thus stable dewatering characteristics over the entire running time.

Flow resistance is reduced in the Z direction due to optimally

set pore volume and the water can flow more rapidly through the fabric, into the grooves of the cover.

A further advantage is the improved abrasion resistance of the paper and the roll side of the fabric.

All Voith’s press fabrics that have the specially developed polymer structure come under the family name of E-Flex.

The structural optimization with polymers can be worked into the various levels of the press fabric, depending on which characteristics need to be optimized. Structural optimization of the papermaking surface optimizes the start-up behavior and gives an improved paper and board surface.

Voith Canada Inc. 905-543-4122, www.voithfabrics.com

Seal assembly reduces maintenance on knife gate valve The PMP di-directional series knife gate valve has a one-piece hermetically sealed monobloc body and bonnet, which eliminates potential leakage to the exterior at full design pressure. The valve, manufactured in conjunction with Jash/Schutte Company, complies with and exceeds TAPPI MSS SP-81 and TIS 405-8 standards A unique stem seal assembly eliminates stuffing box and packing requirements, reduces operating torque, and offers reduced maintenance requirements. The bevelled gate edge easily cuts through debris or build-up. The retained seat will not pull out under full design pressure.

Precision Valve Co. 514-331-0729, www.pmpvalve.com

36

PULP & PAPER CANADA

January/February 2010

pulpandpapercanada.com

MILL PROFILE continued from page 38 Since stock prep involves many pumps with electric motors, the mill is moving toward variable frequency drives wherever possible, says Gibson.

The team’s environmental commit­ ment is also channeled into the mill’s end products. Introduced in 2007, Green­ Choice 100 is a packaging board that claims an immaculate environmental pedigree: 100% recycled fibre, carbon neutrality, and manufactured using 100% clean energy to firmly address customers’ sustainability initiatives.

Sklar explains: “As interest in packaging sustainability grew, we thought there was an opportunity for a product that was carbon neutral and made with clean energy. We have about 12 brand owners using it now.”

The carbon neutral and clean energy claims are achieved through offsets, using an independent third party.

“Based on the number of tonnes we produce, we’ll offset an appropriate amount of CO2. For energy offsets, we put clean energy back onto the grid. We use natural gas for drying, so that’s measur­ able, and we know how much electricity is used, so that amount is put back onto the grid. We replace what we’ve used with clean energy,” Sklar comments.

Strathcona is the only paperboard mill in North America to receive the Envi­ ronmental Choice certification, identify­ ing products and services meeting strict criteria of environmental leadership. This certification, received in 2007, covers the full line of Strathcona paperboard prod­ ucts. All Strathcona products are also Eco­Logo certified, and the mill received FSC certification for recycled content in June of last year.

The administration of these various certifications is “quite onerous,” Dor­ rington admits, with audits and third­ party certification.

But, Sklar counters, “The environment and sustainability are an intrinsic value of what we do. Now that brand owners have focused on packaging sustainability, we’re selling Strathcona as a leader in environ­ ment and sustainability. We want to be the first choice they call.”

Thanks to its history of green choices, Strathcona has the numbers to back up its claims. Each year, the mill has less impact PPC on the earth’s resources. pulpandpapercanada.com

January/February 2010 PULP & PAPER CANADA

37

MILL PROFILE

A History of Green Choices Long before environmental stewardship became a household term, the management team at Strathcona Paper insisted that concern for the environment and natural resources be a guiding

By Cindy Macdonald, Editor principle.

A

t Strathcona Paper, a 100,000tonne clay-coated, recycled paperboard mill situated in farmland near Napanee, Ont., respect for the environment has been standard operating procedure for years.

The results of that policy are measurable, and flow right to the bottom line: electricity use per tonne is dropping, water use per tonne is dropping, fossil fuel use per tonne is dropping.

“Since I’ve been here, which is 20 years, this company has always been environmentally conscious, long before it was popular,” says operations manager Troy Gibson.

The mill’s environmental objectives are generally measured by intensity, i.e. usage per tonne. So a positive change in intensity can be achieved either by lowering usage, or raising the amount of tonnes produced with equal input.

The company solidified its environmental commitment in 2001 by achieving ISO 14001 certification and is now the only 100% recycled clay coated paperboard mill in North America with ISO 14001 certification. “What that’s given us is a very disciplined approach to the environmental aspects of our operation. We are very driven by what that brings to the company,” says Mark Sklar, president and COO.

The Strathcona Paper management team: (l to r) Frank Dorrington, Troy Gibson, Terry Kimmett, and Mark Sklar.

38

PULP & PAPER CANADA January/February 2010

“It encourages us to look at many different areas of our operation, and address them.

“Being a small company helps, because we don’t have a high level of bureaucracy,” he adds. “We pride ourselves on making decisions quickly.”

As Gibson notes, “The same group is making environmental, safety, and production decisions.”

One of the mill’s ongoing goals is to reduce water usage per tonne. “We have a tremendous focus on recycling as much water as possible,” says Gibson.

As a result, says Frank Dorrington, environmental supervisor, “We’ve eliminated cooling water discharge, so we have no risk of environmental exceedence on that front, because it is a closed system.”

Water used in the mill all goes to a central collection point, where it is screened. Strathcona has converted to DSM screens, which are stationary, gravity-fed screens that need no electricity.

Stock returns to the pulper; the water is reused in the process.

Today, 85% of the water used in manufacturing at Strathcona is recycled. Water returned to the adjacent Napanee River is thoroughly cleansed and cooled, and the returned effluent makes a positive contribution to the river’s aquatic ecosystem.

Strathcona composts all biosolids and provides this material to local farmers who spread it on their soil as organic compound.

Other mill systems have also come under scrutiny. An automation system was installed in the early 2000s. At that time it was the first Metso DNA control system in North America. In 2001, Strathcona completed a $25-million investment in state-of-the-art technology at the mill to deliver higher quality, more consistent paperboard. continued on page 37 pulpandpapercanada.com

Combustible Dust Explosions Are you at Risk?

Across a broad spectrum of industrial processes, dust can become the fuel for explosions resulting in multiple deaths and injuries to workers and extensive damage to property.

Investigation of such accidents has revealed that the material safety data sheets (MSDSs), which are regulated by the Workplace Hazardous Materials Information System (WHMIS), inadequately describe dust hazards for those substances implicated in these explosions and that there is a general lack of awareness of this hazard amongst company workforces.

How can it happen?

Combustible materials that have been implicated in dust explosions include coal, chemicals, wood dust, rubber, grain dust, sugar, flour, and a number of metals such as, aluminum.

When combustible dust is dispersed in a confined area and exposed to a source of ignition it can burn very rapidly.

The initial explosion can cause dust that has settled over a period of years to become airborne resulting in a secondary explosion that propagates throughout the plant, often with catastrophic results.

Who is at risk?

Industries at risk of dust explosions include: metal processing, wood product manufacturing, chemical manufacturing, food and pharmaceutical production, grain storage, fabrication of rubber and plastic products, and coal-fired power plants.

For further information, please visit the Government of Canada Web site › whmis.gc.ca

Workplace Système d’information sur Hazardous Materials les matières dangereuses Information System utilisées au travail

whmis.gc.ca

Virgin fiber. Reclaimed fiber. Moral fiber.

It’s how the best paper is made. With strength of character and firmness of purpose. For 60 years, Buckman has provided just that to the paper industry. We’ve grown into a global success by aligning our business model with our customers’ specific needs. With Buckman, you get continuity, commitment, and innovation. You get professionals who see your success as a measure of their own.

Find out how we can help your mill save time, energy, and money.

Visit buckman.com or call 877-BUCKMAN.

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