ALUMINIUM WORLD JOURNAL 2019

Aluminium World Journal

REEL-Alesa Ship Unloader named GARPUR located at ISAL Aluminium Plant, Iceland.

The ship Unloaders name GARPUR is of old Norse Icelandic origin.

GARPUR means Hero, Champion, The Best of Class.

!F"GHG#0(#0**#2(#)(%# 8)9*2(% 0(.#8)9#85)&%;; &)(95)*#;,;9%:#,2%*.2(+ '2+'%5 %<<2&2%(&2%; 0(.# *)>%5 "3?#%:2;;2)(;

!0(4<0&9452(+#"=%&492)(# #,;9%:#<)5#$%4:2(24: .%B%*)8%.#<)5#;:059# :0(0+%:%(9 )<#0#;:%*9%5# )8%5092)(;

!$&'9'%#049):09%.# ;)*492)(#<)5#0#;:%*9%5# 0().%#0(.#:%90*# 2(.))5C)49.))5# 950(;8)59092)(

")9#9%&'()*)+, ;429%#<)5# '2+'#85).4&92B29, C *)> %(%5+, ( D%95)<29 ;)*492)(;#088*2&0E*%#9)#0(, 9%&'()*)+2%;

!().%#/012(+ 345(0&%6## 7892:2;%. 5%95)<29; <)5# %=950#0().%#85).4&92)(# >29' *%;; %(%5+, 0(.#0# *2:29%. ?!"@A

!"#$%&'()*)+,#$!"#$%&'()*)+,-./01% )2#34)5/&1.#6(5# .)*/10)(.#1)#0734)8%#.7%*1%4#%220&0%(&0%.

2

AWJ 2019

Welcome to another edition of Aluminium World Journal.

Global Media Communication Ltd. Manager Director Christopher Fitcher Harris Project Manager Peter Jones Finance Director Ted Garner Published By Global Media Communication Ltd. 85 Great Portland Street, First Floor, London, W1W 7LT United Kingdom Telephone Number: + 44 208 621 2224 Email: gmcproduction@gmx.com Production Design row1graphics

1 g rap

cs hi

ro w

Email: contact@row1graphics.co.uk

gn

si

Gra

Est. 1st. Oct 2009 ph ic D e

The aim of Aluminium World Journal 2019 is to introduce you to some of the many advancements in technology used in both Primary Smelting and processes and Materials Handling.

This edition will provide you with a source of reference which can be utilised for the purpose of education, procurement and networking.

Aluminium World Journal is produced and sponsored by the aluminium industry companies and associations.

I would like to take this opportunity to thank the participating companies and authors for providing editorial, technology innovation reports, case studies and corporate sponsorship.

Should you wish to discuss anything in relation to the content, companies featured in this edition or what you would like us to cover in future editions, do not hesitate to contact us via email at: gmcproduction@gmx.com.

Hope you enjoy the read!

Christopher F. Harris Managing Director Global Media Communication Ltd.

AWJ 2019

3

TOGETHER TOWARDS PERFORMANCE

ALUMINIUM 1EXIVMEPW LERHPMRK ERHɅPMJXMRKɅW]WXIQW JVSQ VSHHMRK XS XLI TSXW

Storage systems

Centrifugal blowers

Ship loaders/unloaders

Bath and carbon recycling plant systems

Dense/solid phase and other EQPXG[KPIǾU[UVGOU Potfeed e.g. HyperDense Phase 5[UVGOUǾ *&25TM) Dosing devices

Pot process control systems Electrolysis handling equipment Carbon: rodding and anode JCPFNKPIǾU[UVGOU DCMKPI HWTPCEG NKHVKPIǾUQNWVKQPU

reel-alesa.com

4

nkmnoell.com

AWJ 2019

TABLE OF CONTENTS PRIMARY SMELTING AND PROCESSES

Latest Innovative Products Enhancing Smelter Competitiveness - RIO TINTO

p.6-11

Aluminium Reduction Cell Thermal Balancing - ALUCELLTECH

p.12-13

Key Performance Indicator Comparisons of Global State-of-the-Art Aluminium Cell Technologies

p.14-20

Scandinavia’s Leading Refractory Solutions Provider - HÖGANÄS BORGESTAD

p.21-23

Modelling of Cathode Wear in Aluminium Reduction Cells - SINTEF

p.24-26

Aluminium Smelters Have Been Focusing On Increasing Productivity By Higher Pot Line Amperage and Getting Better Current Efficiency - MAESTRIA Advances in Low NOx Burner Designs for Aluminum Melting Furnaces - BLOOM ENGINEERING

p.27-29 p.30-33

MATERIALS AND HANDLING

Extension of Life of Cranes in Aluminium Smelters

-

FIVES

p.34-37

Invest Money to Save Money-Innovations and Improvements in Conveying and Handling of Alumina CLAUDIUS PETERS

p.38-42

Controlling energy costs and waste are key to successful aluminium production

AWJ 2019

BRUKS SIWERTELL

p.43-46

5

AP Technology™

Building the new generation anode baking design

Latest innovative products enhancing smelter competitiveness Introduction Smelters face the relentless task of having to improve their cost base and their reliability. Some of the required changes may come from continuous improvement measures while others may occur with the introduction of a step change at the time of asset replacement or modernisation.

Rio Tinto’s AP technology teams keep these situations in mind when innovating and developing processes and products. Three different products in the field of process control, smelter logistics and anode baking furnace are presented below.

ALPSYS is a proven and robust pot control system, capable of managing both AP Technology™ pots and other pots.

During the last ten years the ALPSYS engineering team and system startup experts led a number of potline modernisation projects. Their main challenges were to ensure a safe

deployment of the system on a live potline without any incident/ accident and fully meeting customer expectations in terms of process performance, project planning, reliability and cost.

At t h e s a m e t i m e , s ys te m enhancements have been implemented on ALPSYS to ensure a full integration into the standard architecture of the market in order to optimise the infrastructure and support costs.

ALPSYS is traditionally associated with AP pots but it is also running non AP potlines successfully. Another trial on other technology pots has been performed, delivering impressive results: the average daily pot voltage decreased by nearly 100mV, 95 per cent of all anode effects were treated automatically and the total anode effect over voltage was reduced by 85 per cent.

6 PRIMARY SMELTING AND PROCESSES

Deployment on a live potline: A method customized for each situation This ambitious objective has been achieved with the development of a standardized methodology with world-class practices in EHS management.

Key aspects of such revamping projects:

• Minimize the impact on the

existing infrastructure to reduce cost, work and time, • Manage the temporary loss of process control during the conversion to ALPSYS, • Mitigate risks due to electrical hazards and co-activity of ALPSYS installation with normal pot operations.

The new equipment is adapted to each client’s specifics allowing to replace up to 33 pots per day with minimum

AWJ 2019

AP Technologyâ&#x201E;˘ ALPSYS V15 has been started in two smelters and is about to be started in two other. V15 contains as standard the latest features of the ALPSYS product encapsulated in a completely renovated HMI based on solid, modern and efficient ergonomics.

MAX 2.0 - A first industrial autonomous vehicle in a smelter

vehicle, inventory levels and storage locations, to determine where the MAX robots should go and when.

Imagine a fleet of sleek vehicles working quietly and safely to move tonnes of material around an aluminium smelter, with minimal supervision. This is the vision of the MAX autonomously guided vehicles (AGV) project developed by AP technology and its partner ECA Group.

MAX carries out its tasks in the whole smelter thanks to a guidance system based on SLAM technology that first maps the plant and then guides the robot without the need to adapt existing infrastructure or workshops. MAX can therefore easily replace driven vehicles already in use in existing plants.

An aluminium smelter is a challenging work environment. Heavy and hot loads must be carried in strong magnetic fields, in high temperature areas, both indoors and outdoors, no matter in what weather conditions.

After a successful proof of concept with a full-scale prototype (MAX 01), AP Technology and ECA Group developed and manufactured the first industrial version - MAX Anode.

ALPSYS front view

change to the existing infrastructure.

Following this method, 3700 pots in 17 potlines has been converted in the last decade.

New features on ALPSYS: APM4 and V15 AP is working on a new generation of potmicro called APM4 and has launched the V15 ALPSYS version to ensure the full system is ready for Industry 4.0 challenges.

Key features of the new APM4 include its high degree of compatibility with standard remote I/O cards and ASI networks, Ethernet communication, Web standardized user interface accessible through mobile devices like tablets, compiled code security, modern system tools, graphic display and a fully decentralized pot control system with autonomous pot panel. The equipment can also be changed very fast in case of pot panel breakdown.

AWJ 2019

AP Technology developed a new concept to optimize the various crewed trucks moving heavy loads such as liquid metal and anodes around an aluminium smelter and make them safer. The MAX concept is a fleet of autonomous guided and agile vehicles with heavy-lift capacity and intrinsic safety systems to transport and handle these loads.

AP technology and ECA Group developed LISA (Logistic Integrated Solution for Aluminium). This safe, environmentally sustainable and highly productive autonomous transport solution consists of several MAX vehicles controlled by a fleet management system which provides real-time updates on the status of each

MAX Anode and its management system have been tested in ECAâ&#x20AC;&#x2122;s premises and are now being delivered to Liberty Aluminium Dunkerque smelter (France) for a trial period during which it will assume its share in the day to day anodes pallet transport activity.

Moving metal is the other big part of the transport workload of a smelter and a bigger version of MAX anode is being considered for such metal transport.

Beyond the robot fleet and its management system, AP Technology and ECA provide associated services to their customers, in particular their know-how to prepare and manage the integration of LISA in their plant.

PRIMARY SMELTING AND PROCESSES

7

AP Technology™ construction to provide a rebuild window of 27 days. On 21 December 2017, the NG sections were handed over to BBA operation.

Today, after 18 months of operation, the solution provides safety benefits, such as a significant reduction in the exposure of refractory maintainers to heat and fibers as refractory maintenance activities occurring in the pit are greatly reduced.

To manage the expected fluewall bending, a specific procedure has been implemented to limit the impact of coke additions and removal in the baking pits and two mechanical devices have been designed to provide lateral stability to the refractory flue walls when the pits are empty and to straighten the fluewall.

MAX 2.0 - A first industrial autonomous vehicle in a smelter

This partnership is unique in the aluminium world and provides a complete solution from the concept to the implementation in the plant.

The new generation anode baking design The New Generation (NG) anode baking design is the latest AP Technology™ breakthrough innovation for Anode Baking Furnaces. The NG design not only answers the demand for increased productivity while avoiding the negative effects of fire cycle decrease, it will also allow major CAPEX and OPEX savings in the future.

Bell Bay Aluminium (BBA) smelter selected the NG design for an industrial trial on a 33m long fluewall.

The trial was included as part of a rebuild project in Q4 2017.

The erection was completed without any safety incident and within schedule. One of three fire groups was temporarily removed during the

On the process side, adjustments were made to the internal flue wall pressure (draught) and the target firing curves to ensure complete combustion of fuel in the furnace. The anode properties of the NG area anodes mirror those of standard design anodes, but with lower standard deviation.

A key measure for the NG’s design success is the lifetime of the fluewalls.

The measurements and audit campaigns show positive results

Breakout box The choice of name, MAX™ is linked to its key properties: being Modular, Autonomous and able to cross (X) over between different parts of the plant MAX™ 01 Stats

MAX™ ANODE Stats

Dimensions

5.3 metres long x 3 metres wide

8.5 metres long x 3 metres wide

Maximum Load

5 tons

12 tons

Maximum Speed

18km per hour

15km per hour

8 PRIMARY SMELTING AND PROCESSES

AWJ 2019

AP Technologyâ&#x201E;¢

World leader in the manufacturing of Automated Guided Vehicles (AGV) for the light metal industry www.hencon.com

AWJ 2019

PRIMARY SMELTING AND PROCESSES 9

NobelClad completes portfolio AP Technology™ with new innovative patent

TO COMPLETE OUR PRODUCT PORTFOLIO, NOBELCLAD PRESENTS: ETJ3000+ Aluminium stud

Since the invention of explosion welded clad in 1966, NobelClad has remained a driving force for the aluminium industry, providing strong bimetal pieces and innovative solutions for challenging process environments.

In 1998, «ETJ2000» revolutionized the market thanks to its fine titanium interface. In 2008, ETJ3000 was introduced to offer ever higher performance at high temperatures.

Transition joint ETJ3000 +

Anode carbon block

Today, ETJ3000+ addresses the challenge of increasing the aluminium thickness of the clad while maintaining optimal robustness. This allows operation managers new possibilities to reduce costs by: • Extending the life of short stems with a thicker clad.

• Improving the electrical performance by reducing the proportion of steel in the clad.

NobelClad is thankful to Aluminerie Alouette for their partnership and support in testing and qualifying ETJ3000+.

TM

10 PRIMARY SMELTING AND PROCESSES

ETJ3000 +

CONTACT US TO LEARN MORE ABOUT THE BENEFICIAL PROPERTIES OF ETJ3000+. +33 (0)6 31 14 69 29 - dgauthier@nobelclad.com

www.nobelclad.com

AWJ 2019

AP Technology™

Building the new generation anode baking design

after 35 fire cycles as no deterioration has been found and performance is as expected.

After eighteen months, the financial breakeven point has been reached for BBA. This validates the technical and economic viability of this new breakthrough technology. In addition, the NG design can easily be implemented on a partial ABF

rebuild and is an enabler for anode production debottlenecking and size increase. The technology is expected to be fully demonstrated in 2020, when the fluewall will reach 60 rounds of fire.

Conclusion Each plant has its own challenges.

In order to better fit with the smelter objectives as well as with the existing

Gain for BBA- Statement Compare to classic design (%)

installations and infrastructure, the three new products discussed above need a localisation phase.

By keeping a modular and parametrised approach in developing new solutions, Rio Tinto’s AP Technology team minimizes the time and budget required before finalising the implementation of its products on site and provides the best overall value to customers.

Gain for BBA - Statement 6 sections over 48 (kUSD)

Gain for BBA - Projection Full furnace – 48 sections (kUSD)

Installation Cost

-14

Anode Production

+17

> 500 per year

> 4,000 per year

Gas consumption

+30

> 70 per year

> 560 per year

AWJ 2019

PRIMARY SMELTING AND PROCESSES 11

ALUCELLTECH Aluminium Reduction Cell Thermal Balancing | Will Berends, AluCellTech Inc. hot, aka ‘red shell’, on which surfaces the observant operators typically apply compressed air jets to provide localized cooling. This treatment is costly in energy but is necessary to prevent molten aluminium from contacting and chemically dissolving the steel shell which can lead to a tapout within hours.

This article describes the benefits and methods of thermal balancing of aluminium reduction cell ‘potshell’ walls to extend potlife and improve cell performance.

Aluminium reduction cells, or ‘pots’, operate in a narrow temperature range of approximately 7˚ – 12˚Celsius above the electrolyte ‘bath’ melt temperature. These temperatures enable dissolution of the alumina feed, while still enabling a frozen layer of the bath, aka ‘ledge’, to freeze on the inner surface of the potlining to protect the steel potshell. Depending on pot size, a potlining costs between $100,000 - $300,000 USD, with a lifecycle of ~1,500 - 3,000 days. Based on the cell’s production rate of aluminium, the potlining costs an average of ~$75/ metric ton of aluminium produced, or ~5% of total production costs.

The local thickness of the frozen bath ledge inside the perimeter of the pot is constantly changing due

to variations in ambient temperature, process requirements such as anode changes, bath chemistry variations, power fluctuations, and anode effect

Thermal image of pot sidewall

Thermal image of underside of pot shell

among other causes. Localized melting of the frozen bath ledge exposes the refractory potlining to corrosion by the molten bath, with a risk for early sudden pot failure (‘tapout’). Prior to a localized tapout the steel potshell walls will glow red

12 PRIMARY SMELTING AND PROCESSES

The hottest area of the shell, and at most risk of potlining damage, is a horizontal band around the perimeter, at the elevation adjacent to the bath and molten aluminium interface. Additional hot spots may occur immediately above each collector bar outlet due to the higher concentration of electrical current and related resistance heating through the adjacent cathode and potlining.

Most reduction shells use vertical steel plates, welded on to increase the passive air cooling of the shell, however these cannot be added during normal cell operation. AluCellTech’s magnetic mounted aluminium heat sinks can be applied quickly to operating pots and may be located only on the required hot spots as identified with thermal imaging.

The greater surface area of the cooling pins, and higher thermal conductivity of the aluminium material, as compared to steel plates, can reduce the temperature of the potshell that the heatsinks cover by up to +100˚ C or more depending on concentration and total coverage of the heat sinks. The heatsinks can be applied to hot spots up to 575 ˚ for emergency treatment or applied early in the pot lifecycle to obtain a longer potlife.

AWJ 2019

ALUCELLTECH of the adjacent cathode surface, also leading to shortened pot life.

The recent adoption by many smelters of copper enhanced collector bars used in their pot’s cathode assemblies has reduced the heat normally generated within the cathodes, leading to an increase in bath toe and increased occurrence of anodes becoming frozen in place.

Magnetic heat sinks mounted between steel cooling fins

Excessive frozen bath, typically occurring in pot corners, may also interfere with cell performance by freezing anodes in place, which prevents the anode’s required vertical movement, or which may cause damage to the rods when trying to break the anodes free.

The frozen bath ledge may also freeze over parts of the cathode surface, aka bath ‘toe’, which changes the local concentration of electrical current flow into the cathode, generating voltage disturbances, aka ‘pot noise’, that reduces current efficiency, and may increase the rate of corrosion

External Insulation of the cold sections of potshell can aid in reducing frozenin anodes and eliminating bath toe over the cathode surface. The use of AluCellTech’s magnetic mounted insulation blankets allows an easy application of insulation at the desired locations and may be easily removed and reused as desired.

Thermal balancing of the high/low temperature areas of the potshell enables the reduction cell to tolerate a wider range of bath temperature before risk of tapout, or of frozenin anodes and bath toe related pot noise.

The use of magnetic mounted heat sinks or insulation blankets for passive cooling or insulation provides a convenient and cost effective method of extending potlining life and improving cell performance.

Magnetic blankets mounted near pot corner

AWJ 2019

PRIMARY SMELTING AND PROCESSES 13

Key Performance Indicator Comparisons of Global State-of-the-Art Aluminium Cell Technologies Alton Tabereaux1 Marc Dupuis2

Comparison of Amperage and Aluminum Production

1Consultant

(formerly Alcoa), 105 Country Club Lane, Muscle Shoals, AL 5661, USA attaber@aol.com 2GéniSim Inc., 3111 Alger St., Jonquière,

Québec, Canada G7S 2M9 marc.dupuis@genisim.com We have reviewed thirteen cuttingedge aluminum cell technologies in the global aluminum industry operating from about 404 to 600 kA. They include Northeastern University Institute NEUI600, SAMI SY500 & SY660, Rio Tinto AP60, APXe, AP44 & AP40, UC Rusal RA-550, GAMI GY530, Emirate Global Aluminium DX+ & DX+ Ultra and Hydro Aluminium HAL4e & HAL4e Ultra

• Four ‘super-high’ amperage cell

technologies, SY600, NEUI600, AP60 and RA-550 operate at the highest ‘world bench-mark’ amperage from 550 to >600 kA and therefore have the highest aluminium production, 4.30 to 4.6 t/pot-day of the 13 cell technologies as shown in Region I of figure 1, [Ref 1]

Figure 1. Comparison of amperage and aluminum production for advanced aluminum cell technologies.

Many important Chinese cell technologies in the range 400 kA and higher are not included in this article due to inaccessibility of performance KPI data and other relevant information, for example SY400, NEUI400, GY420, NEUI500 and GY500.

• Two pilot prototype cell

technologies, HAL4e Ultra and APXe operate with the lowest “world bench-mark” energy consumption, ≤ 12.0 kWh/kg Al and less than 3.8 volts/pot as shown in Region I of figure 2.

Comparison of Energy Consumption and Voltage

• Three other cell technologies,

GY530, APXe and SY500 operate from 500 to 535 kA with aluminium production between 3.70 to 3.9 t/ pot-day in Region II.

• Six cell technologies, DX+, DX+

Ultra, HAL4e, AP44, HAL4e Ultra and AP40 operate at lower amperages from 404 to 460 kA in Region III and therefore have lower aluminum production, less than 3.50 t/pot-day.

Figure 2. Comparison of the energy consumption and cell voltage for advanced aluminum cell technologies.

14 PRIMARY SMELTING AND PROCESSES

AWJ 2019

• Three advanced cell technologies,

SY600, HAL4e, and GY530 have potlines that operate with the lowest “world bench-mark” energy consumption ≤ 12.50 kWh/kg Al and less than 3.95 volts/pot in Region II.

Key Performance Indicators of Low Energy Pilot Plant Test Cell Technologies

• Five technologies, NEUI600, SY500, DX+ Ultra, RA-550 and AP60, operate between 12.5 to 13.0 kWh/kg in Region III.

• Six technologies, AP60, AP40,

AP44, RA-550, DX+ Ultra, and DX+ operate at traditional cell voltages ≤ 4.00 volts/pot in Regions III & IV.

In January 2018, Hydro Aluminium began operating 60 advanced aluminum cells, (48 HAL4e cells and 12 HAL4e Ultra cells) at its pilot aluminum smelter in Karmøy, Norway [Ref 2]. The HAL4e cell technology has an aluminum production of 3.44 tonnes per potday when operated at 450 kA and a 94.9% current efficiency.

It has a specific energy consumption of 12.40 kWh/kg when operated at 3.95 volts/pot as shown by the KPI results in Table 1. This represents a 12% reduction in the specific energy consumption when compared with the world average of 14.1 kWh/kg aluminium and 10% reduction when compared with Hydro’s own average of 13.8 kWh/kg aluminium for traditional cells, personal communication (May 6, 2019).

The HAL4e Ultra cell technology has an aluminum production of 3.22 tonnes per potday when operated at 418 kA. It has the lowest, “world benchmark”, specific energy consumption 11.70 kWh/kg aluminum for prototype test cells when operated at 3.75 volts

AWJ 2019

Table 1. Performance Indicators for Low Energy Pilot Plant Cells operating between 418 and 504 kA.

as shown by the KPI results in Table 1, personal communication (May 6, 2019).

Rio Tinto Aluminium APXe Cell Technology Four Rio Tinto Aluminium APXe prototype test cells have operated at the LRF smelter at Saint Jean de Maurienne, France since 2008 [Ref 3]. The APXe cell technology has an aluminum production of 3.83 tonnes of aluminum per pot-day when

operated at 503.7 kA and a current efficiency of 94.4%. The technology also achieves a “world bench-mark” specific energy consumption of 11.96 kWh/kg aluminium for protype cells when operated at 3.79 volts/pot as shown by the KPI results in Table 1, (personal communication (May 13, 2019).

Emirate Global Aluminium DX+ Ultra Cell Technology Five DX+ Ultra Technology

Figure 3. Potline of Hydro Aluminium HAL4e Cells at the Karmøy smelter in Norway.

Comparison of amperage and aluminum production for advanced aluminum cell technologies.

PRIMARY SMELTING AND PROCESSES 15

demonstration pots were started in the Eagle pilot line at Jebel Ali, Dubai in 2014 at 450 kA and operated at increased amperages up to 460 kA. During the period Jan to June 2016, the DX+ Ultra cell technology had a production of 3.46 tonnes of aluminum per pot-day when operated at 459.8 kA and 93.5 % current efficiency. It has a specific energy consumption of 12.87 when operated at 4.04 volts/ cell as shown by the KPI performance results in Table 1, [Ref 4].

Rio Tinto Aluminium AP4X Cell Technology Rio Tinto Aluminium has succeeded in the continuously development of the AP30 platform towards higher amperage up to 405 kA in amperage booster sections at St. Jean de Maurienne during 2009-2011. In 2015, the Alma plant in Quebec, Canada was the first AP30 smelter to operate above 400 kA, [Ref 5].

The AP44 cell technology was developed in the booster cell test sections at Dunkirk and Alma smelters during 2014-2016 [Ref 5]. The AP44 cell technology had a production of 3.29 tonne per pot-day of aluminum when operated at 440 kA and a current efficiency of 92.8% CE%. It has a specific energy consumption of 13.500 kWh/kg energy when operating at 4.20 volt/pot as shown by the KPI results in Table 2, (personal communication (May 13, 2019).

Figure 4. RTA APXe cell technology cells at LRF aluminium smelter in France.

has a specific energy consumption of 13.095 kWh/kg energy when operating at 4.16 volt/pot as shown by the KPI results in Table 2. The first of 594 AP30 cells at the Alouette smelter was implemented with AP40 technology in June 2018, [Ref 6].

460 kA since April 2016. The DX+ cell technology had a production of 3.49 tonnes of aluminum per pot-day when operated at 460.2 kA and 94.2 % current efficiency. It has a specific energy consumption of 13.44 when operated at 4.25 volts/pot, [Ref 7].

Emirate Global Aluminium DX+ Cell Technology

SAMI SY500 Cell Technology

DX+ Technology was installed in Al Taweelah Operations Potline 3 which was fully commissioned by mid-2014.

It began operating stably at 440 kA and has been operating at above

The SY500 cell technology was designed and implemented by the CHALIECO Shenyang Aluminum &Magnesium Engineering & Research Institute Co., Ltd (SAMI). During 2011, the first potline of 288 SY500 cells

Key Performance Indicators of Aluminium Cell Technologies Operating From 405 to 550 kA

The AP40 technology was implemented at the 420 kt/y Kitimat smelter in 2015-2016. During a 4-month period in 2016, the AP40 cell technology had a production of 3.08 tonne per pot-day of aluminum when operated at 404.6 kA and a current efficiency of 94.6% CE%. It

16 PRIMARY SMELTING AND PROCESSES

Table 2. Key performance indicators for advanced cell technologies operating between 405 to 550 kA.

AWJ 2019

Figure 5. RTA AP40 Cells at Kitimat aluminium smelter in Canada.

with a capacity of 388 kt aluminum were started at the Liancheng smelter in Gansu Providence. The SY500 cell technology has a production of 3.70 tonnes of aluminum per potday when operated at 500 kA and a current efficiency of 92.0%. It has a specific energy consumption of 12.79 kWh/kg aluminium when operated at 3.70 volts/pot as shown by the KPI performance results in Table 2, [Ref 8].

at the Yunnan Shenhua smelter.

The GY530 cell technology has a production of 3.97 tonnes of aluminum per pot-day when operated at 530 kA and a current efficiency of 93.0%. It has a specific energy consumption of 12.497 kWh/kg aluminium when operated at 3.97 volts/pot as shown by the KPI performance results in Table 2, (personal communication (April 15, 2019).

There are four potlines of GY500 cell technology cells operating during 2019 (1.7 million tpy of capacity) at aluminum smelters in China and three potlines of GY500 cells are reported to be under construction (1.3 million tpy of capacity).

Rusal RA-550 Cell Technology Five RA-550 kA pilot cells were started up at UC RUSALâ&#x20AC;&#x2122;s Sayanogorsk

By 2015 there were reported to be more then eleven potlines of SY500 cells (>4 million tpy of capacity) operating in China and more potlines with SY500 cells were reported to be under construction at aluminum smelters in China.

GAMI GY530 Cell Technology The CHALIECO Guiyang Aluminum & Magnesium Engineering & Research Institute (GAMI) designed and developed the GY500 and GY530 cell technology, [Ref 8]. A potline of GY530 cells started operation at the Xingren smelter in Guizhou, China in 2018. An additional potline of GP530 cells is reported under construction

AWJ 2019

Figure 6. A potline of EGA DX+ Cells at the EMAL aluminum smelter in Abu Dhabi.

PRIMARY SMELTING AND PROCESSES 17

Figure 7. A potline of GAMI GY530 Cells at Xingren smelter in Guizhou, China

Aluminum Smelter in 2016. [9] The RA-550 Rusal cell technology cells has a production of 4.26 tonnes of aluminum per pot-day when operated at 550 kA and a current efficiency of 96.1%. It has a specific energy consumption of 12.78 kWh/kg Al when operated at 4.12 volts/pot as shown by the KPI performance results in Table 2, (personal communication (December 2018).

Key Performance Indicators of Super-High Amperage Cell > _ Technologies ( 570 kA)

Rio Tinto Aluminium AP60 Cell Technology In September 2013, Rio Tinto Alcan completed the complete startup of a 38-cell pilot plant (31 first-generation pots and 7 AP60 second-generation pots) at Arvida smelter at Jonquière, Quebec, Canada which has an annual of 60,000 tonnes of aluminium, [Ref 10].

The AP60 cell technology has a production of 4.41 tonnes of aluminum per pot-day when operating at 570.7 kA and a current efficiency of 95.9% and has a specific energy consumption of 12.850 kWh/kg Al when operating at 4.14 volts/pot. In January 2015, Jonquière achieved an amperage of

Table 3. Technical parameters for super-high amperage cells.

over 600 kA in the smelter’s boosted section, (personal communication (May 13, 2019).

NEUI600 Cell Technology The Northeastern University worked with Northeastern University Engineering & Research Institute Co., Ltd (NEUI) to designed and commercialize the world’s first complete 600 kA potline in December 2014. with a capacity of 300,000 tpy [Ref 11]. The NEUI600 cell technology has a production of 4.57 tonnes of aluminum per pot-day when operated at 600 kA and a current efficiency

18 PRIMARY SMELTING AND PROCESSES

of 94.6%. It has a specific energy consumption of 12.443 kWh/kg Al when operated at 3.95 volts/pot as shown by the KPI performance results in Table 3, (personal communication (May 7. 2019).

As of May 2017, there are 6 NEUI600 potlines (1374 cells) operating at the Weiqiao aluminium smelter with a total capacity of 2.21 million tpy. Currently, there are 9 potlines in China using NEUI-600 technology with a total capacity 3.49 million tpy.

AWJ 2019

Figure 8. Five RA-550 Cells at the Sayanogorsk smelter in Russia.

SAMI SY600 Cell Technology The Shenyang Aluminum & Magnesium Engineering & Research Institute Co., Ltd. (SAMI) designed and developed the technology for the SAMI SY600 cell technology. The industrial pilot test of 12 SY600 kA aluminum reduction pot technology was carried out in 2012 at the Liancheng Branch of Chalco.

Three new high amperage 600 kA potlines, 210 cells per potline, were built in 2012 at the Xinfa aluminum smelter in Shandong, China. The first potline was put into operation in November 2015 with a capacity of 350,000 tpy. Two additional 600 kA potlines were started-up in 2016.

Together, the three 600 kA potlines have an annual capacity of 1.0 million tpy.

The SY600 cell technology has a production of 4.48 tonnes of aluminum per pot-day when if operated at 600 kA and a current efficiency of 92.8%.

It has a specific energy consumption of 12.140 kWh/kg aluminum when operated at 3.78 volts/pot as shown by the KPI performance results in Table 2, [Ref 8].

AWJ 2019

Figure 9. Potline of RTA AP60 Cells at the Arvida smelter in Canada.

Figure 10. Potline of NEUI600 cells at the Weiqiao Smelter in China.

PRIMARY SMELTING AND PROCESSES 19

References 1. A.T. Tabereaux, Top “New Technologies Revolutionizing Aluminum Smelting”, Light Metals Age, Feb 2019, pp.6-10.

2. Svendsen, Andrea, “Karmøy Technology Pilot – World Leader in Primary Aluminum Energy Efficiency,” Light Metal Age, February 2018, pp. 20-23.

3. Sébastien Becasse, Olivier Martin, Bertrand Allano, Yves Caratini, and Denis Tinka, “APXe Cell Technology: 7 Years of Low Energy Operation”, Light Metals 2018, pp.699-704.

4. Abdalla Alzarooni, Nadia Ahli, Alexander Arkhipov, Sajid Hussain, Lalit Mishra, Sergey Akhmetov, and Kamel Alaswad, “DX+ Ultra Industrial Version: Preheat Start Up and Early Operation”, Light Metals 2018, pp.721-729.

5. Pascal Thibeault, Louis Guimond, Véronique Dassylva-Raymond, Joseph Langlais, René Gariépy, and Olivier Martin, “AP44 Development at Alma”, Light Metals 2018, pp.737-744.

6. Patrice Desrosiers, Martin Robitaille, Pierre Luc Over, Silvino Caetano, René Gariépy, Olivier Martin, Pascal Robert, “The Successful Implementation of AP40 Technology at Kitimat”, Light Metals 2017, pp.793-799.

7. EGA Website, “(DX+) Excellence Through Innovation”, June 2016: https://www.ega. ae/media/1014/ega-technologies.pdf 8. Bingliang Gao, Zhaowen Wang, Zhongning Shi and Xianwei Hu, “History and Recent Developments in Aluminum Smelting in China (GY500, SY500, SY600, NEUI600),” Travaux 46, Proceedings of 35th International ICSOBA Conference, Hamburg, Germany, October 2-5, 2017.

9. Viktor Mann, Andrey Zavadyak, Vitaly Pingin, Vitaly Platonov, and Iliya Puzanov, “RA-550 Cell Technology: UC RUSAL’s New Stage of Technology,” Travaux 46, Proceedings of 35th International ICSOBA Conference, Hamburg, Germany, October 2-5, 2017; Light Metals 2018, pp.715-719..

10.“AP60 and APXe : A breakthrough in productivity, energy consumption and emissions”, AP Technology Newsletter, Issue 20, March 2015, 11.Yungang Ban, Jihong Mao, Yu Mao, Jing Liu, and Gaoqiang Chen, “Development and Industrial Application of NEUI600 High Efficiency Aluminum Reduction Cell”, Light Metals 2018, pp.705-713.

Figure 11. Arial view of two NEUI600 potlines at the Weiqiao smelter, China.

Figure 12. Potline of SY600 cells at the Liancheng aluminium smelter in Shandong China.

Figure 13. Arial view of three potlines of SAMI SY600 cells at the Liancheng smelter, China.

20 PRIMARY SMELTING AND PROCESSES

AWJ 2019

Höganäs Borgestad Scandinavia’s leading refractory solutions provider Höganäs Borgestad has always been a provider of refractory solutions to the global aluminum industry. Höganäs Borgestad has a long tradition and started producing refractories in 1825.

WE ARE PROUD TO PRESENT OUR NEW BARRIER BRICK VIKING 20 VIKING 20 is an optimally designed brick solution with the following attributes; • A product matching the needs of barrier brick in pot-cell lining • Having superior Cryolite and Aluminum resistance • A cost-effective solution to the customer(s)

Cryolite test <2 cm2

Kryolittest: 950 oC/24 h 55 x 40 mm Kryolitmix: 60 % (90 g) Na3AlF6 + 40 % (60 g) NaF

Our range of innovative products will reward you with a cost effective refractory solution and the lowest refractory cost per ton of produced metal. We aim to answer your needs and solve your problems even before you ask us.

Building a new future: We are committed to ensure the future of us as well as our valuable customers. In this process, we started the most modern monolithic refractory plant in Bjuv, Sweden in 2016, with a manufacturing capacity of 30,000 MT/ year.

The key features of this modern new plant are: • High level automation.

• Intensive mixing technology for monolithic mixes, to ensure a high degree of homogeneity of additives level of as low as 0,005%.

Robustly designed products Our product lines are ranging from conventional, low cement, ultralow cement and no cement, suiting installation through vibration, selfflowing, rodding, pouring, gunning, pumping and shotcreting.

PURE ALUMINIUM test at 800°C /72 hrs.

Refractories and services to improve your performance Höganäs Borgestad offers superior refractory solutions to the aluminum.

At the same time, we supply a range of special products and services to other industries that use refractory materials – both within Scandinavia and globally.

AWJ 2019

Research and Development:

In order to fulfill your current and future needs, we continuously research and develop new products and upgrade our existing solutions to incorporate new technical trends and safety requirements.

We have a state of the art laboratory at our production facility in Bjuv and our R & D team is composed of engineers and professionals with deep understanding of your operating practices.

Using the latest technology and processing methods, they strive to develop the best materials or the most challenging applications. We are equipped with sophisticated equipment’s f.e. particle size analyzer, thermal conductivity measurement, Refractoriness under load, hot abrasion tester, microscopy etc, to completely characterize and understand the refractories.

Research is the heart of our business.

Focus on energy saving monolithic technologies, to reduce carbon footprint, through reducing drying times and thus making the developments sustainable.

PRIMARY SMELTING AND PROCESSES 21

Aluminum Höganäs Borgestad has been supplying the refractory needs of aluminum foundries since the establishment of the aluminum industry in Norway in the early 20th Century. Our range of materials has become the preferred refractory solution for this industry.

We provide complete refractory solutions for all the major production processes — cathodes, holding furnaces and anodebaking furnaces, as well as a number of special applications with top-class refractory materials that will help keep your costs low and promote your competitiveness.

Our product range includes: • Chamotte and high-alumina bricks • Monolithics (castables & gunnables) • Prefabrication • Mortars • Insulation material • Anchors • In addition to our high-quality products, we provide a range of services spanning from design to installation.

to cryolite as possible to prevent bath compounds from penetrating into underlying material.

Our new barrier brick Viking 20 is a proof of new innovation , environmental focus and correct quality for the application.

Our monolithic Thermocast 7.4.1 has become a standard in the aluminum industry to fill and seal open gaps in the refractory lining around the cathode steel bar. Thermocast 7.4.1 is very easy to work with, delivering exactly the right combination of strength and flexibility. Höganäs Borgestad delivers this product in flex bags tailored to your order, ranging from 25 to 1000 kg, so you get exactly the right amount of product for your installation.

Almost all melting and holding furnaces have one thing in common; each one is unique! That is why we have developed a comprehensive range of refractory solutions to improve the performance of your unique production.

In furnace linings, the focus is to maintain a stable heat balance throughout the furnace’s lifetime, and keep the isotherm for the freezing point of the metal within the hot face lining to minimize the risk of a breakout of molten metal.

Electrolytic cells Höganäs Borgestad understands the demands of the production process in detail, and we are an experienced supplier of refractory material for electrolytic cells. The key strength of Höganäs Borgestad is own chamotte clay of excellent quality, which is calcined and classified for manufacturing barrier bricks in Bjuv, Sweden. This allows us to control the manufacturing process, quality as well as the microstructural design of brick that is resistance to cryolite or bath components. Barrier bricks must provide as much protection resistance

Casthouse

All of our materials are regularly monitored by a number of quality institutes like SINTEF (the Foundation for Scientific and Industrial Research at the Norwegian Institute of Technology), to assure product uniformity and consistency.

Crucible Lining Höganäs Borgestad can design your crucible lining with bricks, in-situ casting and for prefabricated shapes including crucible lid.

22 PRIMARY SMELTING AND PROCESSES

AWJ 2019

Other refractory expertise Höganäs Borgestad, can offer solutions to all other applications involving aluminum industry.

Höganäs Borgestad has in house installation and is cooperating with some of the most experienced international installation companies in the world.

Conclusions:

We offer a number of flexible, proven solutions based on bricks or monolithic that will help you to achieve this.

Designing the lining is also a matter of finding the right balance between output volume and the lining’s functional lifetime, the thicker the brick, or castable lining, the longer its life. In addition, identifying the right amount of insulation is an important factor in getting the best solution.

The extreme environment of the holding furnace makes renovation an ongoing process, regardless of the quality of the refractories and their installation. Höganäs Borgestad offers you full maintenance support for your furnace.

Höganäs Borgestad has experience and expertise in both monolithic and bricks for casthouse applications. Alsafe 90 BP is a classic example of cast house refractory bricks. This is a phosphate bonded bauxite brick, with superior, resistance to aluminum liquid metal contact. Aluminum resistance test performed by an external laboratory SINTEF has proven superiority of this brick for Aluminum alloy contact applications.

AWJ 2019

Aluminium resistance of Alsafe 90 BP Alsafe 90 BP from Höganäs Borgestad is tested against the aluminum alloy AA 7278 according to the procedure described on the previous page.

Two test-cups were prepared for the test.

Alloy AA 7278 Si < 0.15 % Fe < 0.20 % Cu 1.7 - 2.1 % Mg 2.7 - 3.0 % Zn 6.8 - 7.2 % Cr 0.18-0.22 %

Höganäs Borgestad has long withstanding experience and expertise in developing, selecting and installing the right refractories depending on the needs of customers in all areas of aluminum manufacturing industry. Equipped with its own R&D and production center in Sweden, Höganäs Borgestad has a modern monolithic plant delivering the newest refractory technology for our customers benefit.

Roger Kvam Marketing / Technical Sales Höganäs Borgestad Borgestadbakken 2 N-3712 Skien, Norway Tel: +47 35 54 23 00 Mobile: +47 95 09 96 32 E-mail: roger.kvam@hoganasborgestad com Website: www.hoganasborgestad.com

Results: There was no sign of penetration or reaction between the Alsafe 90 BP and the aluminum alloy. Pictures of the cut-face are shown.

PRIMARY SMELTING AND PROCESSES 23

Modelling of Cathode Wear in Aluminium Reduction Cells 1

Tao Li 1, Stein Tore Johansen 1,2 Asbjørn Solheim 2 Department of Energy and Process Engineering, Norwegian University of Science and Technology, Trondheim, Norway 2 SINTEF Materials and Chemistry, Trondheim, Norway Keywords: Cathode wear, Electrochemical, Carbide, Bath film

Introduction The service life of aluminium reduction cells is limited by cathode wear, which is shown as a typical double “W” profile [1]. It has been mainly attributed to the formation of the carbide (ref. carbide below) growing from the bottom of the layer [2]. A bath film [3] is observed locating between the molten metal and cathode block, formed by the melting of the sludge at the bottom of the cells. A developed model assumes a simplified geometry where the metal flow, which is driven by the Lorentz force, results in shear stress and motion of the bath film. The simulations demonstrate how the local current distribution and the mass transfer of carbide from the cathode surface and into the bath film result in uneven cathode wear profiles.

Model of fluid flow The simulations are performed in ANSYS Fluent R15.0 by using a 3D transient solver, in which a simplified electrolysis cell with a cylinder shape geometry, as shown in Figure 1, is applied. The thickness of the bath film is set to be 1 mm initially.

Geometry of electrolysis cell.

The bulk fluid flow is driven by magneto-hydrodynamic forces, while the electrical current density is described by the continuum form of Ohm’s law, representing conservation of the electric charge. The multiphase volume of fluid (VOF) model is applied to the mass conservation of the bulk of the fluid. The momentum is described by the Navier-Stokes equations,

Figure 1 Geometry of electrolysis cell.

considering the Lorentz force acting on the fluid. The internal magnetic field is considered in the model. Effects of externally caused magnetic fields will have to be considered later. The cathode is given a specified electrical current density, 1) uniformly j=8000 A/m2 (ref. Case-1 below); 2) a “W” shape distribution considering the location of current collector bar in the cathode (ref. Case-2 below). The modelling details in ANSYS Fluent are given in previous work [4].

The flow of the bath film is driven by the shear force from the molten aluminium. The solution in the current model is to assign a virtual bath film in the first layer of grid on the cathode surface, because the film is often too thin and would generate extremely large and fine meshes if it should be resolved by the VOF model. The continuity equation of the bath film is modelled in terms of its thickness.

The focus of the current model is to establish the governing model of the bath film and demonstrate its importance on mass transfer.

Therefore, the bath film is simulated

24 PRIMARY SMELTING AND PROCESSES

as a closed system without considering melting/dissolution of the sludge. The bath film is assumed to be parallel to the cathode surface, thus its velocity normal to the cathode surface is zero.

Therefore, the viscous shear stress and their velocity gradients in x and y directions are ignored.

Mass transfer of cathode wear As shown in Figure 2, diffusion dominates the mass transfer of the carbide in the vertical direction in the bath film due to its slow velocity.

The removal of the carbide layer is driven by its local concentration in the bath film. The mass transfer of carbide from the bath film and into the interface with molten Al is dominated by diffusion and is inversely proportional to the local thickness of the bath film. On the molten metal side, the flux of carbide is driven by its concentration difference between both sides. The mass transfer coefficient is a function of the local friction velocity of aluminium which is a function of the shear stress from the metal at the interface. The concentration of carbide at the interface is in a local

AWJ 2019

thermodynamic equilibrium. The dissolved carbide concentration Cf in the bath film is controlled by diffusion and convection due to the flowing bath film.

Results and discussions Flow of bulk fluid and bath film Figure 3 shows the flow pattern of molten aluminium and bath at the profile of x=0 (see Figure 1). The changes of the predicted bath film thickness with time are shown in Figure 4. The flow of the molten aluminium pushes the bath film towards the periphery of the cell in Case-1. The film builds up fast at the beginning and is approaching to a steady state after 200 s. Nevertheless, the bath film is squeezed towards the centre of the cell in Case-2.

Figure 2. Mass transfer of carbide.

(a). Uniform current distribution (Case-1).

Mass transfer of carbide According to the simulation results, the resistivity of dissolved carbide transport, from bath film into metal, is mainly located at the metal side at the interface. When the bath film is saturated with carbide, the carbide removal rate would be independent of the bath film thickness. The cathode wear profiles in Figure 5 are actually a limiting case where the bath film is saturated with carbide and carbide

(b). Non-uniform current distribution (Case-2).

Figure 3 Flow pattern of molten aluminium and bulk of bath.

(a). Uniform current distribution (Case-1)

(b). Non-uniform current distribution (Case-2).

Figure 4 Change of bath film thickness with time.

AWJ 2019

PRIMARY SMELTING AND PROCESSES 25

can only escape by mass transfer into the molten metal flowing above the cathode. The realistic average cathode wear rate was reported ranging from 2 to 5 cm/year, which is much larger than those shown in Figure 5.

Thus, the possible outflow of bath film would contribute largely to remove the dissolved carbide away from the cathode.

In Figure 6 JA1 indicates the cathode wear rate due to carbide mass transfer from bath film into molten metal; while JA14 C3 indicates the cathode wear rate by dissolving carbide from the cathode surface. The concentration of carbide in the bath film is specified in the brackets.

(a). Uniform current distribution (Case-1).

Figure 5 Cathode wear rate dominated by mass transfer from bath film into molten aluminium.

(b). Non-uniform current distribution (Case-2).

Figure 6 Influence of carbide concentration in the bath film on the cathode wear rate.

When the carbide concentration is close to its saturated value in the bath film, the mass flux JA14 C3 and JA1 are pretty close, but the carbide dissolution rate is still too small to account for the realistic cathode wear rate. In Case-1, the cathode wear rate by carbide dissolution reaches to realistic values when Cf = 0.8Cfsat The contribution of the mass flux of carbide into the molten metal is shown by JA1 (0.8Csat) and the rest of the dissolved f carbide is taken out of the bath film by film outflow. Similar conclusions can also be drawn in Case-2. Thus, the outflow of the bath film contributes largely to the cathode wear.

Conclusions In this preliminary modelling study, we can draw the following conclusions.

(1) In Case-1, the bath film is tending to be pushed towards the periphery of the aluminium reduction cells. In Case-2 (non-uniform current distribution) the bath film is built up in the centre of the cell.

(2) At the interface between the bath film and the molten aluminium, the mass transfer of carbide is dominated by the mass transfer on the metal side. The mass flux into the molten aluminium is not enough to account for observed cathode wear rates.

(3) The outflow of the bath film contributes largely to the cathode wear.

In future work the outflow of the bath film and the external magnetic field will be included in the model, then representing more realistic cells.

Acknowledgement The present work was financially supported by the DuraMat project. Permission to publish the results is gratefully acknowledged.

References 1. E. Skybakmoen, S. Rørvik, A. Solheim, K.R. Holm, P. Tiefenbach, and Ø. Østrem: Light Metals 2011, 1061-1066.

2. B. Novak, K. Tschöpe, A. P. Ratvik, and T. Grande: Light Metals 2012, 1245-1250.

3. Ø. Østrem, Cathode wear in Hall Héroult cells, Ph.D. thesis, NTNU, 2012.

4. K. E. Einarsrud, E. Skybakmoen, A. Solheim: Light Metal 2014, pp. 485-490.

26 PRIMARY SMELTING AND PROCESSES

AWJ 2019

Aluminium smelters have been focusing on increasing productivity by higher pot line amperage and getting better current efficiency Current Efficiency is an important cell parameter that measures what fraction of the electric current results in aluminum production. Proper use of anode signal can be a great process control tool for improving it.

The industrial cell is a complex system where all parameters are closely interrelated. Incremental improvements can be made by managing marginal contributing factors when you can identify their probable origin.

Recently, a considerable interest has been noted in the literature in detection of local cell conditions based on individual anode current measurements, which fit well with the global trend of Data Mining, the statistical analysis of large pools of data to find hidden correlations so called Big Data. We vision a great potential of such applications in aluminium smelters considering itâ&#x20AC;&#x2122;s getting easier each year to collect and process a lot of data. We will concentrate on one path of application we know working well and can be implemented without great investment from operators.

Uniform anode current distribution is basic for stable pot operation and best efficiency. Obviously, the smelter staff needs to monitor it by some means.

The most common method to monitor the anode current distribution is to measure the voltage drop between

AWJ 2019

two points on each anode rod with a fork, the so-called anode millivolt (mV) drop. We can easily postulate that all the aluminium smelters do this measurement on a more or less regular schedule, but not all reach the maximum possible payback by doing it.

The trend to increase cell size or to increase the amperage of older cell design makes global sensing of only one measurement element for the whole cell, not sufficiently reliable to really understand the various variation happening inside the unit.

Moreover, another trend is amperage increase creep for an existing smelter, realizing as one of the more cost efficient ways to increase the specific production, and really a success story for many aluminum smelters when well done. One way to increase amperage is to reduce the anode-cathode distance (ACD). So, close monitoring of each anode becomes more and more critical; no need to detail how the current efficiency is very sensitive to ACD variation, especially when it gets very low where instability and drift can

make the goal of increasing CE very hard to reach.

Thereby, typical problems following amperage increase are the loss of current efficiency (CE), increased frequency of anode problems, increased anode effect frequency, and increased cathode wears resulting in shorter cell lives. It is well documented that many anomaly encounters in cell operation, will be preceded by some pattern occurring in the current distribution.

Many various local cell phenomenon may affect operation and may induce interesting signal pattern characteristics on a probed anode.

Diagnosis and correction of operating cells events history help build a knowledge base that can be put in relation with the anode signal measurement looking for: Anode kicking, anode spike, anode setting accuracy, low alumina dissolution.

Maestria Solutions, has developed Millivolt Anodes (mVa) tool, including a lightweight fork, automatic recording of the anode mV, pre-programmed sequence of measurements and automatic modern data transfer to the computer. This tool has been in use in several smelters, in some for over 25 years. This tool can be easily integrated at low cost into actual operation team doing work for the aluminium cell.

It even does most of the same jobs as an on-line current monitoring that needs to be installed on each anode of all cells, at a very high installation, operating and maintenance costs.

PRIMARY SMELTING AND PROCESSES 27

Uniform anode current distribution is the basis of stable pot operation and best pot performances. Some people consider that 80 % of pot operation problems are caused by anodes.

Even though this can be viewed as an exaggeration for some, it is well known that the anodes are a primary source of potential problems in real operation. Therefore, it is logical to monitor closely the anode behavior in order to find and early correct any irregularity.

closely is the anode setting, well known as disturbing the cell operation for several hours after setting, if not several days. The anodes are set to a certain target height with respect to the old anode butt for proper operation of the cell. Anode setting accuracy in typical operational condition is influenced by many factors. Even in the best situation, it is quite common to have some margin of error in the actual height adjustment.

Operators have typically found the following pattern:

The general concept for individual anode current measurements is to regularly monitor the values and trends of the data sets and to deduce various local cell conditions by matching patterns for known process behaviors, where the proper statistic analysis helps to guide the corrective actions. Starting with Statistical Process Control (SPC) method, the data can be scrutinized in many ways and by using some smart ways to highlight specific pattern occurring in the data set, it becomes a great diagnostic tool.

Anode set too low has the following consequences: • High current flow in this anode • Prone to cracking carbon, causes bad connection in cast iron-carbon contact • Early instability as metal waves increase, higher noise • Computer adds resistance modifiers, • Detrimental to current efficiency, reduces aluminium production

A good operation to be monitored

Anode set too high has the following consequences: • Low current flow in this anode,

28 PRIMARY SMELTING AND PROCESSES

• • • • •

Longer time to heat up, Local bath freezing, side ridge formation under the anode Risk of setting anode on side freeze with down bridge moves Current increase in the other anodes, instability, noise Resistance modifiers added

The new Maestria mVa unit, uses Bluetooth for communication that enables bidirectional communication with an external device. When doing the actual measurement around the cell, it is not mandatory to be in communication with the computer since the fork stores the data for transfer, when the operator gets back near a computer later on, at the end of the run. It has a battery that can make the system run typically for a few weeks on one charge, depending on the amount of usage in the potroom.

Also, individual Light Emitting Diodes (LEDs) give extra information to guide the operator in determining a normal or abnormal measurement; it even allows seeing if an anode is unstable, using customizable software trigger parameter. This is especially useful

AWJ 2019

after anode change. Another LED gives feedback of a good reading for the operator. The measurements can be downloaded via Bluetooth for history and analysis purpose on a PC and process control software.

Using this equipment also reduces the overall workload for anode change and makes the anode changing easier to follow, which is very useful in case of amperage increase on an older potline.

A well-trained operator can easily do one cell in less than one minute, and be implemented easily into the day to day routine already done by the smelters on their potline, the payback will overcome greatly the require change.

Hence, there is less time of exposure of workers and thus better health and safety benefits; the ultra-light design

AWJ 2019

allows quick operation and reduces exposure.

It was found that a great accuracy is needed to really make appeared a small change in the measurement that is symptom of an unwanted phenomenon appearing or starting to appear in the cell, which by a side effect is reflected by a subtle difference in the anode signal. This is not easy for on-line measurement system to reach that precision.

Through the years, millions of measurements taken in many smelters on thousands of cells show that those techniques work. The operation gains and increases of current efficiency confirm that the system offers a very good solution for better anode control in an aluminium smelter, just to recall that 1% CE improvement is documented in some smelters. (ref: Millivolt Anodes

and Cicero - new tools for better pot and potline control, ICSOBA 2015).

Many abnormal or even potential faulty situations can be detected early. The system has been useful as a diagnostic tool to avoid operational drifts when creeping amperage, and has helped to maintain good process control. The new version with the built-in sophisticated electronics and software can also be closely adjusted to each smelter technology. Some new functions enable quick detection of various noise patterns occurring in the cell, helping the operator at the cell to apply quickly the proper corrective action. We will introduce also this year new analysing tools that will simplify the statistical data manipulation to be applied to the measurement generated by the system and that will make easy to push the critical information needed for the operation directly in the process control system.

PRIMARY SMELTING AND PROCESSES 29

Advances in Low NOx Burner Designs for Aluminum Melting Furnaces Burner Hardware improvements which can be employed to lower NOx levels in aluminum melting applications.

INTRODUCTION In the 1980’s, regenerative combustion systems became standard for many batch processes and became particularly popular for aluminum melting furnaces. It is rare, now, for an aluminum melting furnace to have any other kind of combustion system except for a regenerative one.

For reasons discussed below, first generation regenerative systems had dangerously high emissions of nitric oxides (NOx). In the subsequent decades, through a combination of improvements to the burner hardware and ancillary combustion equipment there has been a general trend toward lower NOx formation. After a brief discussion about the mechanics and contributing factors to NOx creation, this paper will show some of the strategies currently employed in regenerative systems to mitigate its formation Formation of NOx Nitric Oxides, when chemically combined with certain volatile organic compounds (VOC) can form smog and low altitude ozone. While these compounds can further create acids, in their vaporous forms, they can aggravate pulmonary ailments such as asthma. There are post-processes that can remove NOx from the waste gas, these systems can require specific process parameters (operating temperatures, for example) and/or extra capital equipment. Generally, it is better to mitigate the formation, rather than try to remove it after the fact.

at extremely high temperatures (above 2780°F [1525°C]) to form NOx. This reaction is very sensitive to temperature, and the rate diminishes rapidly below that temperature. In order to minimize formation, it is necessary to do any one or more of the following: lower concentration of oxygen, lower concentration of nitrogen, and/or lower the temperature of the flame envelope. Except for the case where the oxidizer is pure oxygen (compared to air, or even oxygen enriched air), nitrogen and oxygen are always present in the combustion air, so the task of minimizing nitrogen and oxygen, is simply an exercise in minimizing extra air in the process.

Before leaving the general discussion of NOx, it is worth noting that for some fuels (particularly oils and solid fuels) there is usually some amount of nitrogen chemically bound in the fuel often in the form of HCN or NH3.

There is very little that the combustion engineer can do to affect the amount of that fuel bound nitrogen (FBN) that becomes NOx.

Regenerative Technology

1850’s, regeneration is still one of the most common ways to increase combustion efficiency in many industrial applications (conventional cold air combustion is approximately 30%-35% efficient at a temperature of 2000°F (1000°C), while regenerative systems can show a combustion efficiency of almost 75% on a gross heating value basis) for a substantial savings in fuel. Regeneration requires burners to work in pairs. One burner fires while the other recovers heat from the exhaust by passing the waste gas through a porous bed of ceramic media. After a fixed cycle time (generally 20-90 seconds) the flows reverse and the originally firing burner then exhausts, and the exhausting burner fires. (See Figure 1.) In this manner, it is possible to lower the waste gas temperature to approximately 300oF-400oF (150200oC), and to raise the combustion air temperature to within 200oF (110oC) of the process temperature.

This cycling requires a set of valves for fuel and combustion air, as well as a cycle valve and suction fan for exhaust gas. In addition to the cycling valves, there are flow control

Although originally developed in the

At the most basic level, nitrogen (usually in the form of atmospheric, diatomic nitrogen: N2) and oxygen (also in diatomic form: O2) combine

30 PRIMARY SMELTING AND PROCESSES

Figure 1 – Representation of cycling process for regenerative burners

AWJ 2019

valves for each zone that modulate the amounts of air and fuel to each zone based on the heat demand.

NOx Mitigation Strategies Because these regenerative systems are so common for aluminum melting furnaces, combustion engineers have developed many strategies to mitigate formation or emissions through advancements in burner design.

Combustion Staging Because NO x formation is so strongly dependent on the peak flame temperature, and peak flame temperature depends on combustion air temperature, regenerative systems, with extremely high combustion air temperatures, see flame temperatures several hundred degrees higher than for a cold air system. Figure 2 shows flame temperature as a function of combustion air temperature for a premixed flame with all other parameters held constant. (Note that the relationship is not quite linear, although across the temperature range represented here, it is to a good approximation.) Clearly, flame temperature (especially at regenerative combustion air temperatures) is sufficiently high as to produce generous amounts of NOx. Finding a way to lower the peak flame temperature is an effective way to cut NOx formation dramatically. Flame temperature is at a maximum when the exact amounts of air and fuel are well mixed and present at the same physical location. One of the most common ways to lower the flame temperature, while still efficiently using the heat available from the fuel, is to delay the mixing through staging of the fuel or air. Doing so causes regions within the flame envelope that are fuel rich or fuel starved. Of course,

AWJ 2019

as a whole, the flame envelope has the appropriate amounts of fuel and air, but because they are not mixed as well, the temperature is much lower, and NOx formation is much reduced. Figure 3 schematically shows how combustion staging works. In most cases, there are physically separate holes for the different stages of air (i.e. first stage and second stage air). Remember, the correct amounts of air and fuel allow complete combustion, but the delayed mixing means that the flame temperature is sufficiently reduced, thus decreasing NOx formation.

Staging is one of the most common,

and effective, ways to mitigate NOx formation, particularly for regenerative systems. Typically, there are separate air connections for each stage of combustion air. It is possible, as well, to stage the fuel. Conceptually, air and gas staging are identical, but practically, it is difficult for proper staging with gas.

For most calorifically rich fuels, the proportion of air compared to fuel is large, meaning that there simply isnâ&#x20AC;&#x2122;t as much fuel available for proper staging. For example, with natural gas, there are about ten volumes of air for each volume of fuel, meaning that it is easier to divide the air volume into additional stages.

Figure 2 â&#x20AC;&#x201C; Flame Temperature vs. Combustion air temperature

Figure 3 - Schematic representation of staged combustion

PRIMARY SMELTING AND PROCESSES 31

External Flue Gas Recirculation (EFGR) and Waste Gas Entrainment For further reductions in NOx, it is possible to introduce inert waste gas into the flame envelope. Historically, the waste gases entered through an additional connection on the burner body after collection from the flue.

Handling this (often hot) gas, as well as additional piping and operational considerations present unique challenges. While these Flue Gas Recirculation (FGR) systems still exist, it is possible to realize similar benefits without external hardware. Proper design of the burner port allows for entrainment of furnace atmosphere into the root of the flame. (See Fig. 4.)

Here, the waste gases enter the flame envelope under the natural eddies and flows of the burner itself. This strategy does not require additional hardware, and it is easy to tailor the port shape to particular firing parameters and furnace geometry. Diluting the root of the flame can dramatically reduce peak flame temperature.

The extreme staging in the latest generation is apparent compared to the classic third generation.

(See Figure 6.) The fuel and air enter the burner on opposite sides of the burner baffle, thus ensuring delayed combustion, and lower peak flame temperature. As discussed above (§Combustion Staging) the entire flame envelope maintains a stoichiometric ratio, and thus optimal heat release, while suppressing the peak flame temperature. Using this latest generation technology can provide a reduction to about 65% of current (third generation) emissions performance.

Cycle and Flow Control Valves A classical regenerative system makes use of two independent valves; one modulates to control the flow (of air,

fuel, or exhaust) to the zone, and the other is an on/off cycle valve that switches the flows between the burners in a pair. (See figure 7.) By placing a positioner on the cycle valve, it is possible to combine the functions of both types of valves thus eliminating all flow control valves. Not only does this reduction in equipment make the control system simpler, and reduce capital expense, it means that it is now possible to control the flow to each burner in a pair independently. Inevitably, the media beds will experience different rates and amounts of fouling and deterioration meaning that a common flow control valve position will result in different performance out of each burner.

Controlling flow independently to each burner ensures optimal performance out of each burner in the zone.

Combining Air Staging and Waste Gas Entrainment Over time, combustion engineers have developed better technology for improvements in emissions performance. Figure 5 shows the progress made as combustion engineers improved burner design for better NOx performance. (These data are for identical operational parameters across the different burner types.) The first big reduction in NOx came from using EFGR, roughly cutting the expected NOx in half. Further reductions (third generation) were possible due mainly to waste gas entrainment. The latest generation of Low NOx regenerative burners make use of extreme air staging as well as waste gas entrainment to see the lowest levels of NOx production currently available.

Figure 4 – Representation of port block waste gas entrainment.

Figure 5 – Relative NOx formation for progressive generations of burner technology

32 PRIMARY SMELTING AND PROCESSES

AWJ 2019

In addition, independent control of the burners ensures that the proper amount of combustion air flows to each, thus optimizing the staging, as well as the minimizing excess air.

Benefits for Aluminum Processing The nature of aluminum melting is such that fouling of the regenerative beds often occurs (either from splashed molten metal, or from impurities burning off of the scrap). It is very rare that the beds in a pair of regenerative burners foul in identical ways or at similar rates. In almost all instances, one bed will foul more quickly than the other. With a standard regenerative system, a common flow control valve serves two (or more) regenerative beds. It is easy to imagine that the actual air flow through two dissimilar beds with a valve in a common position will be different. Inevitably, one or more burners do not fire optimally, leading to inefficiencies in fuel use and/or increases in emissions or dross.

Individual control of the air flow to each burner optimizes combustion efficiency, minimizes emissions, and enhances productivity and product quality.

Conclusions While regenerative systems are very popular for aluminum melting furnaces mainly because of greater fuel efficiency, the inherent high combustion air temperatures mean that minimizing emissions (particularly Nitric Oxides) is tricky.

With advancements in hardware burner design (air staging, waste gas entrainment, etc.), there are new techniques available that can bring specific NOx generation

to levels within 10-15% of those seen with cold air systems. These systems are well suited for aluminum melting applications, and most new installations are adopting some or all of these new technologies to enhance efficiency and to decrease environmentally harmful emissions Mr. Michael Cochran Bloom Engineering mcochran@bloomeng.com

Figure 6 â&#x20AC;&#x201C; Comparison of standard and air-staged regenerative baffles

Summary For comparative purposes, Table 1 shows expected emissions under various combustion schemes. It is worth noting that while the specific rate of production (NOx Average: mg/ Nm3) basis might be higher for the regenerative systems, the rate, and annual potential to emit (PTE) are both lower than for the corresponding conventional firing systems because regenerative systems consume roughly half the fuel. Therefore, even though the average NOx for a latest generation regenerative system is about 10% higher than for a cold air system, the annual PTE is about 56%!

AWJ 2019

Figure 7 - Partial Schematic showing standard control and cycle regenerative valves.

Table 1 â&#x20AC;&#x201C; Comparative emissions for various combustion schemes

PRIMARY SMELTING AND PROCESSES 33

Extension of Life of Cranes in Aluminium Smelters Denis Chapdelaine1 and Frédéric Moreira Pereira2 1. Sales Manager Fives Services Inc., Montréal, Québec, Canada 2. Service Development Manager Fives ECL, Ronchin, France Corresponding authors: denis.chapdelaine@fivesgroup.com or frederic.pereira@fivesgroup.com Abstract The life cycle of aluminium smelters is comparable to the life of human beings. All over the world aluminium smelters need to work longer to sustain an ever competitive economy.

As smelters age, their health must be checked. Often, corrective actions must be taken in order to ensure safe and efficient duty for the remaining lifetime. Based on Fives’ 70 years of experience and a comprehensive installed base of more than 1300 ECL Tending Machines operating in the world, Fives is able to provide accurate and valuable assessment of the health of aging equipment. The assessment is a theoretical and field study performed in six steps. Such assessment is especially important for equipment that are more than 20 years old.

required, and the necessary actions taken.

2. Maximizing the Efficiency and Safety of Mature Smelters In particular, many of the world’s potroom cranes were built during or before the 1980s and are close to 40 years old. They were designed according Fédération Européenne de la Manutention (FEM), (the European Materials Handling Confederation), rules with a limited life span, equivalent to 10 years for mechanical assemblies (gearboxes, wheels, hoisting, etc.) and 20 years for structures. Computerized calculations were not available at the time, and conservative safety factors were applied during the design and manufacturing phases. Many cranes are still in use, providing a high level of safety, operating performance and serviceability. Nevertheless, a

thorough asset management program is needed for this equipment to ensure that it complies with the latest safety standards and that they will continue to do so for the remaining operational life of the smelter. To maximize the customer’s safety and efficiency, FIVES has devised an Extension Of Life (EOL) program based on the company’s 70 years of experience on a fleet of over 1 300 operating cranes. Around 50 % of ECL cranes have exceeded their theoretical design life span for structures and the EOL program has been designed to help clients build an appropriate asset management plan for their machines. It will also help them face, or anticipate, insurance companies’ requirements.

Curves in Figure 1, show different design limits, around 5 to 10 years for mechanical parts and 25 years for

Keywords: Smelter life time, pot tending machine, assessment of equipment health.

1. Introduction Some 85 % of aluminium smelters which are currently producing metal are over 20 years old. And with the aluminium prices regaining their strength, many of these old smelters are under pressure to produce metal safely and efficiently for longer than they were originally commissioned for.

Their industrial equipment has aged.

Although it may still be operating, it has reached a stage where an overall assessment of its remaining life is

34 MATERIALS AND HANDLING

Figure 1. Smelter crane life cycle.

AWJ 2019

structure. The likelihood of failures increases closer to the end of design life. Proper maintenance and use will assure service exceeding any projected “life expectancy”. Conversely, the lack of maintenance and operational abuse will reduce greatly the estimated “life expectancy”. C1 and C2 are curves that represent distribution of reliability characteristics versus constraints distribution. Operation costs increase over time as the crane needs more frequent maintenance and spare parts.

Typically the operational period for industrial cranes is from 10 to 20 years. Fives makes calculation of its equipment for a life cycle of 20 to 25 years for structures, and 10 years for mechanisms. In figure 2, X axis is the Time and Y axis is the number of cycles. Each equipment is designed for certain number of cycles. Once

(A) Represents the case of a nominal use in conformance with original specifications. B and C are cases where crane is underutilized in terms of cycles. The assessment will validate the remaining life cycle before reaching the number of theoretical cycles (defined by the design) before carrying a possible overhaul. A, B and C can be considered as complete equipment or components depending on the scale study undertaken.

3. A Six-Step Program The EOL program is implemented through six phases. Each program is tailored to be specific to the customer’s needs and operational conditions. The first step is a preparation phase. The critical equipment of the smelter is listed by family. According to FIVES’ database, the equipment type and

AWJ 2019

To build an accurate picture of the machine and its life to date from our own or the client’s files, the following data need to be gathered: The original design statement; [1] to which standard the Machine was designed and any specific references for those items when a general “Crane” standard did not cover. Examples are the DIN reference for Hooks, pulleys, rails etc.

The comparison of the OEM’s recommendation for sustainable maintenance and that found on site via the client’s Computerized Maintenance Management System (CMMS).

Figure 2. ISO/DIS 16716 Cranes with suspended load - Crane life cycle design.

SA: Special assessment (Specific inspection), DWP: Design working period, GO: General overhaul, UD: % use compared to original design, T: Time of use, A: Component replaced at 1st GO, B, C: Component inspected at 1st GO, X: Design working period of components B and C (actions to plan).

the number of cycles is reached, if it is requested. to make an extension of life study, various scenarios can be followed such as: General overhaul, reinforcement of components or replacement of complete subassemblies in order to give back more cycles and life expectancy to the equipment (A).

with the customer and covers cycleduty data (anode changing operation, metal tapping, anode beam raising, etc.) in great detail, dimensional and quantitative data (number, type and weight of new and used anodes, amperage of the potline, number of pots and cranes, etc.), and historical data (smelter milestones, refurbishment work, etc.).

production site are prioritized (if the program is conducted over several smelters). This step is necessary to ensure that the on-site asset study will meet the customer’s interest and its economic and social realities.

The second phase of the program is that of data collection. A thorough collecting campaign is conducted

Review of third party examination reports of critical items including pressure vessels and ultrasonic testing of axles, pulley shafts and pins.

Review of historical load cycles report as issued from the client.

The original as built General Arrangement, detailed drawings and operational manuals giving tested speeds, loading and Proof/Safe Working Load (SWL) testing as well as any deflection tests carried out were reviewed. Original certificates were not made available by the client.

Any modifications instigated by the client and any related drawings.

From all of these and the inspection reports a comprehensive catalogue.

MATERIALS AND HANDLING 35

A precise chart of the duties of each machine is created, allowing assessment of the exact machine components’ cycles (Figure 3). Based on this, preliminary cycle calculations are made by FIVES’s engineering department to identify the stressed areas and the most probable failure points of the machines. In the third phase of the EOL program, these results are compared to the original and theoretical FEM class in relation to number of cycles. In addition to this, a cumulative damage study, according to the Palmgren-miner’s rule (Cumulative damage model based on ISO 16716) will help determine the criticality of the machine’s structural wear and fatigue [2]. A new calculation of the equipment FEM class is conducted, based on actual requirements of the standards. Finite element calculations are carried out on identified and critical structures (Figure 4). Weak or areas not meeting today’s design criteria are consequently selected for particular attention during the on-site inspections and for further action, such as: extension of the subassembly lifetime, replacement, refurbishment or a bespoke surveillance program.

A thorough structural, mechanical and electrical inspection is performed by a team of FIVES’ experts in the customer’s premises (Figure 5). This constitutes the fourth phase of the EOL program. The team will inspect all parts of the cranes, particularly concentrating on the known identified problematic areas (Figure 6). During inspection, all mechanisms are tested and hoisting units are load tested per local regulations. The structural parts identified as sensitive in the Finite Element Analysis are controlled with non-destructive tests. The electrical components are thermally checked

36 MATERIALS AND HANDLING

Figure 3. Total use per mechanism.

Figure 4. Finite element calculations are carried out on identified and critical structures

to detect possible faults and all the safety facilities are controlled.

Subsequently, a fact-based inspection report is produced. A crane map and check-list precisely identifies all of the crane’s issues, their location, their type (safety, production, maintenance, etc) and gives a criticality classification along with recommendations. The report also highlights: maintenance procedure deficiency, outdated components with limited availability with recommended replacements and potential machine improvements to increase productivity and reliability.

The Status assigned to actions in the report are based upon the criticality scale included in AS 2550 [4] for the assessment of fitness for purpose and can be read as follow:

A = Inspected - No action required Safe for Continued Use B = Adjustments/Repairs made Safe for Continued Use C = Additional repairs required Not Safe for Continued Use D = Urgent repairs required Not Safe for Continued Use E = WARNING: DO NOT USE Technical problems can be benign and only require adjustments or repairs, or at the other end of the scale, they could require the withdrawal of the crane from the production site for urgent repairs to ensure safe continued use. This classification is based on a risk analysis process that combines recalculations using real operating cycles with finite element modelling, and the structural, mechanical,

AWJ 2019

Alucam, Rio Tinto Grande Baie, Intalco, Trimet St Jean de Maurienne, Lochaber, Laterriere, and Aluminium of Greece smelters.

Figure 6. A team of FIVES experts carries out a thorough inspection of a crane in a customer’s smelter.

5. Reference

Figure 5. Study process flowchart.

hydraulic and electrical data from the on-site audit. The final and most important phase of the program consists of the preparation of a life extension scenario. This strategic approach is built jointly by FIVES and the customer’s management.

It aims to produce an added-value document that will enable the building of a successful asset optimization plan for the forecasted operating future of the smelter. Based on factual data, calculations, simulation and FIVES’ 70 years long experience, the EOL program concludes with the production of a report with fact-based tool-set designed to assist the aluminium smelter in adopting the right technical directions and actions to reach their safety and economic objectives.

AWJ 2019

4. A proven approach Fives’ EOL program has been constructed not only according to the expertise on crane audits but also in application of international standards such as the Australian AS1418 / AS2550 standards [3 - 4].

Fives’ expertise in tailor-made cranes is used for interpretation of the results and for building the conclusions and the solutions in order to extend lifetime of the cranes. As part of the development phases, the EOL approach was used for audits on Rio Tinto sites in Australia (BSL, Tomago) and the Alcoa Portland site. The EOL program in its mature form has been implemented at the request of Alcoa (Deschambault, Baie Comeau and San Cyprian) for its complete crane fleet, comprising ECL stud-pulling cranes, Pot Tending Machine (PTM) and Furnace Tending Assembly FTA. It has also been engaged at Aluminérie de Becancour (ABI), Albras, Alouette,

1. Fédération Européenne de la Manutention – F.E.M. 1.001, Rules for the design of hoisting appliances, 3rd Edition Revised, 1998.10.01.

2. ISO DIS 16716, Cranes – monitoring for crane design life, 2012 edition. November 5 2012.

3. Australian AS1418 Standard Set, Cranes hoists and winches, the following are pertinent: • AS 1418.1 – 2002, Cranes, hoists and winches - General requirements • AS 1418.1 – 2002, Cranes, hoists and winches - General requirements • AS 1418.2-1997, Cranes (including hoists and winches) - Serial hoists and winches • AS 1418.3-1997, Cranes, hoists and winches - Bridge, gantry, portal (including container cranes) and jib cranes • AS 1418.14-1996, Cranes (including hoists and winches) - Requirements for cranes subject to arduous working conditions • AS 1418.18-2001, Cranes, hoists and winches - Crane runways and monorails 4. AS 2550.01-2002/AMDT 1-2004, Standards Australia, Cranes, hoists and winches – Safe use.

MATERIALS AND HANDLING 37

Invest Money to Save Money-Innovations and Improvements in Conveying and Handling of Alumina

by CLAUDIUS PETERS Claudius Peters are experts in materials handling and processing systems in the Cement, Coal, Alumina, Gypsum and other Bulk Handling industries. Claudius Peters designs and manufactures equipment for these industries.

Claudius Peters Projects GmbH, Germany and Claudius Peters Technologies SA,France are part of the Technologies Division of Claudius Peters Group GmbH, headquartered in Buxtehude, near Hamburg, with regional offices in the Americas, Europe, China and the Far East, offering turnkey and semi-turnkey systems.

The groupâ&#x20AC;&#x2122;s other principal Division, Aerospace, is engaged in the manufacture of aircraft parts for the European Airbus programme.

Claudius Peters Group GmbH is a wholly owned subsidiary of Langley Holdings plc, a privately controlled UK-based engineering group.

Preface Alumina is a very precious material.

Cautious handling of this pulverized material plays a very important role in the subsequent processing.

Attrition or segregation of the powder during handling and storage has to be minimized.

solutions for the industry: The FLUIDCON conveying system combines low energy consumption and low conveying velocities.

The ANTI-SEGREGATION-SYSTEM is a filling system especially for large silos, especially for application in the alumina industry.

The AERATED DISTRIBUTION SYSTEM - ADS is distributing secondary alumina to the electrolysis cells. It is probably the most energy efficient and material friendly distribution system in the market.

The Claudius Peters EM-Mill is a vertical grinding unit, a perfect equipment for anode coke grinding.

Our TECHNIKUM allows for equipment tests on a semi industrial scale basis. Before we deliver a new product, we test the process in our Technical Center, the TECHNIKUM. The TECHNIKUM is open to our customers, to test new ideas before they are installed in the field.

In the following we will describe the advantages of these specialized systems for the aluminium industry.

Claudius Peters Projects is a very renowned company in the field of materials handling and in the field of special grinding processes.

Low speed pneumatic conveying with FLUIDCON Alumina is a very costly material.

Cautious handling of this pulverized material plays a very important role in the subsequent processing.

Especially for application in the alumina refinery or in the aluminium smelter Claudius Peters offers optimized

Destruction of particles or attrition influences the further processing and has to be avoided. Segregation of

38 MATERIALS AND HANDLING

the powder during storage has to be minimized. Loss of product at takeover-points or deaeration systems is a direct loss of money.

When designing new projects or planning modifications to existing systems, the design of the transport and storage systems plays a very decisive role to the overall success of the installation.

Claudius Peters has therefore developed the FLUIDCON-conveying system, a unique fusion of aeroslide and dense phase conveying which combines low energy demand and low conveying velocities. In the FLUICONsystem the total conveying gas is split into fluidizing gas and axial driving gas.

The fluidising gas it used to aerate the material along the conveying distance and keep the material in a fluid-likestate. Then the axial driving gas is moving the material in conveying direction. By this means the friction of the material is reduced, resulting in a reduced energy demand compared to a standard pipe conveying.

Several FLUIDCON-Systems are in operation worldwide with different products. Conveying distances of the plants installed range from 20 to 600 m with capacities from 10t/h to 220 t/h.

Due to the low conveying velocity and the low friction the energy demand is significantly lower than that of a conventional pipe conveying. This is schematically shown in Figure 2.

The low conveying velocities of the FLUIDCON-system offer a further advantage especially for the alumina handling.

AWJ 2019

Figure 1: Principle of FLUIDCON-pipe and typical Layout of conveying plant

The rate of particle fracture with this conveying system is very low. An example is given below in Figure 4.

Conveying distance in this case was 400m with a vertical height of 35m.

There is only a slight increase in the range of particles smaller 45Âľm with this conveying.

For every conveying task the different options have to be compared and weighed.

Figure 2: Energy demand for different conveying systems

When doing modifications to existing plants there are space restrictions that have to be taken into consideration. An example of a qualitative comparison for different types of conveying options is shown in Table 1.

ANTI SEGREGATION SYSTEM-The best Mix Claudius Peters delivers storage solutions of different sizes for various industries.

The size range starts with small pre hoppers and ends with high-capacity silos.

The main focus in the alumina industry is the cautious handling of the precious

AWJ 2019

Figure 3: Particle size distribution before and after conveying

MATERIALS AND HANDLING 39

material and especially a minimized segregation of the material. The segregation can be counteracted in two ways, avoiding it during filling of silos or homogenizing the material at the discharge. Whatever you need: Yes we can.

With the Anti-Segregation System the material is handled by patented filling tubes at several positions at the perimeter of the silo. These filling tubes transport the material downward and do not allow turbulences in the material stream to occur.

Table 1: Comparison of different conveying systems (green: positive; blue: neutral; red: negative)

Figure 4: Filling of a silo with Anti-Segregation-System

The material leaves the filling tube nearly dust free. The segregation of fine particles during filling of a silo is minimized. New installation or modification, the AS-System works for you.

AERATED DISTRIBUTION SYSTEMLet the material work for you The Claudius Peters AERATED DISTRIBUTION SYSTEM (ADS) is the ideal solution for the distribution of the secondary alumina to the different

40 MATERIALS AND HANDLING

electrolysis cells.

The AERATED DISTRIBUTION SYSTEM (ADS) distributes the alumina from the secondary alumina silo at the fume treatment plant to the different cells in the potrooms. The ADS consists of inclined aeroslides.

The layout of the system is shown in Figure 5.

The ADS is operated by controlling the airflow of the aeration of the different parts of the system. When

the aeration air is switched off, the material flow stops immediately.

The system is deaerated via the pot superstructure to the gas collecting ducts. The inclined aeroslide results in a very reliable operation.

More than 1000 cells worldwide are already fed with the ADS system. The wear rate is very low and the systems need only very little attention. Some reviews of the systems in operation have already been realized and have shown very positive results. A review of

AWJ 2019

the particle size distribution at different positions of a system, for example, revealed, that there is an even grain size distribution at different areas of the system, an excellent precondition for operation (Figure 6).

Whereas with a horizontal aeroslide the coarse material fractions will be found more likely in the first part of the system the inclined aeroslide has a more even material distribution over the entire conveying length.

Compared to this a pipe conveying has high velocities and higher pressure drops over the conveying distance, resulting in scaling or material attrition.

The ADS-system in contrast is using an inclined aeroslide system and is avoiding the before mentioned difficulties.

Modular design Because of its simple modular design, the ADS system fits into existing plants and is also an ideal solution for new installations. The aeration air supply can be realized with plant air, via central supply or using diversified air supply systems.

Figure 5: Layout of AERATED DISTRIBUTION SYSTEM

CLAUDIUS PETERS EM MillContinuous operation and excellent results The Claudius Peters EM Mill is the preferred grinding technology for the production of fine pet coke for the anode production.

The introduction of the vertical spindle EM mill for existing production lines for anodes has improved the consistency and quality of the anodes remarkably. The properties of the fines, characterized by the grain size distribution or Blaine number, can be maintained with less fluctuations

AWJ 2019

Figure 6: Comparison of particle size distribution at different positions (field test)

MATERIALS AND HANDLING 41

Each material is measured for its mechanical behaviour to ensure that our customers get the right solution for their requirement.

The Claudius Peters Technikum is open to clients to check special operating parameters or to identify the effect of special material behaviour.

Conclusion FLUIDCON-conveying â&#x20AC;&#x201C;system, which combines low energy consumption and low conveying velocities.

Figure 7: Claudius Peters-EM-Mill

Figure 8: Installation of EM-mill

compared to conventional grinding mills.

meet any conveying and handling requirement

Continuous operation The capacity of the EM-mill can be adjusted between 100 and 25 percent. The actual capacity can this way be matched to the production requirements avoiding frequent stopping of the mill, i.e. less grinding losses are produced.

Extensive testing, backed by years of experience enables Claudius Peters to design and produce conveying and handling systems that combine high reliability with minimal power consumption.

Operating costs Maintenance requirements are minimized due to the long service life of the grinding elements. During the service life it is not necessary to replace or install grinding balls. The low specific drive capacity of the total plant and the low maintenance requirements make this process much more efficient.

Incorporating conveying lines up to 5000 m in length and an extensive range of diameters, the laboratory allows for the design and supply of systems calculated for optimized process parameters.

ANTI-SEGREGATION-SYSTEM is designed especially for the application in the alumina industry.

The AERATED DISTRIBUTION SYSTEM ADS is probably the most energy efficient and material friendly material distribution system in the market.

The Claudius Peters EM-Mill the finest solution, delivering consistently high quality.

Our TECHNIKUM allows for material tests on a semi industrial scale basis.

Claudius Peters-we know how.

TECHNIKUM- Try it out The Claudius Peters Technikum is a state-of-the-art facility, offering clients the opportunity to test any bulk solid conveying solution or perform laboratory testing of powders.

State-of-the-art technology to Figure 9: Schematic of a closed grinding circuit

42 MATERIALS AND HANDLING

AWJ 2019

energy fluctuate and imbalances can work for or against smelters.

Smelters would like to avoid major fluctuations that can threaten their business stability. As a result, some have negotiated energy deals where the price paid for energy is linked to the market price of aluminium.

Although countries benefit from their aluminium businesses, not everyone is happy.

Opponents point to pollution issues and the negative effect the industry may have on tourism.

When energy costs have such a big impact on the success of alumina smelters, it is surprising that most of them employ sub-optimal bulk discharge systems that can actually increase their energy demands and also result in the unnecessary waste of valuable raw material. In this article I will explain how the use of totallyenclosed screw-type unloaders can benefit the industry.

Controlling energy costs and waste are key to successful aluminium production Juha Huovilainen, Bruks Siwertell Sales Director Director, explains how switching to screwtype discharge systems can help cut the aluminium industryâ&#x20AC;&#x2122;s massive energy bills and increase efficiency by eliminating spillage

AWJ 2019

Primary aluminium production is an energy-intensive process. Locating smelting plants close to cheap sources of power makes good business sense.

This is a factor in alumina smelting operations in countries such as Iceland, with plentiful hydro and geothermal resources. Prices of aluminium and

While recycling aluminium requires only five percent of the energy needed for primary aluminium production, this route can only supply a proportion of the current demand. Therefore, primary aluminium production will remain necessary for many decades, so it is important to apply all possible efficiencies to the process.

Mitigating energy demands Pneumatic systems are widely used for alumina unloading. They have very high energy demands and are far less efficient than screw-type unloaders.

More importantly, pneumatic systems do not handle the alumina very gently; this results in high levels of alumina degradation and the production of MATERIALS AND HANDLING 43

fines (powdery material) which has a serious impact on the smelting process.

The energy demands of aluminium smelting are very sensitive to the percentage of fines in the alumina; the lower the percentage of fines, the less energy required for the smelting process.

We estimate that minimising cargo degradation by using our screw-type unloaders would save the global industry up to US$400 million every year. This figure is supported by real world experience and monitored tests that consistently confirm the extremely low level of fines resulting from discharge using our screw-type unloaders.

Efficient, gentle unloading can make the difference between success and failure in marginal cases; a number of smelters have closed because high energy consumption made their operations unviable.

Cutting waste and protecting the environment

44 MATERIALS AND HANDLING

Reducing energy costs is not the only way in which the industry can benefit from screwtype unloaders. Another discharge technology in widespread use is the grab crane; the downside in this case is the high level of spillage and dust generation. Based on customer experience and test results we estimate that eliminating spillage across the industry would result in savings of up to US$150 million per annum.

Grab cranes can lose up to two percent of delivered cargo through spillage, while our totally enclosed systems eliminate spillage and keep dust emissions to a minimum. Alumina is extremely hygroscopic, seeking to absorb moisture from the atmosphere.

Totally-enclosed unloaders ensure that the alumina remains as dry as possible.

Further savings are made because there is a negligible amount of cleaning when using a Bruks Siwertell unloader. Working conditions are greatly improved and the impact on the port and surrounding areas is negligible.

Clean operations are vital for importers with facilities close to centres of population and commerce who are finding it difficult to meet increasingly stringent environmental regulations.

Performance promises guaranteed We are confident that the global aluminium production industry could save hundreds of millions of US dollars if it made the move from traditional discharge systems to totally enclosed screw-type unloaders.

The savings are delivered in a number of ways, related to the nature, value and processing requirements of alumina. But in all instances, it is the performance of the screw-type unloader â&#x20AC;&#x201C; when compared to the alternatives â&#x20AC;&#x201C; that delivers the results.

Bruks Siwertell screw-type unloaders were introduced to the market in 1974.

They were an instant success, rapidly carving out an important market share.

We have been developing them ever since, so that our latest machines benefit from nearly four

AWJ 2019

customer experience and test results we estimate that eliminating spillage across the industry would result in savings of up to US$150 million per annum.

Grab cranes can lose up to two percent of delivered cargo through spillage, while our totally enclosed systems eliminate spillage and keep dust emissions to a minimum. Alumina is extremely hygroscopic, seeking to absorb moisture from the atmosphere.

Totally-enclosed unloaders ensure that the alumina remains as dry as possible.

fines (powdery material) which has a serious impact on the smelting process.

The energy demands of aluminium smelting are very sensitive to the percentage of fines in the alumina; the lower the percentage of fines, the less energy required for the smelting process.

We estimate that minimising cargo degradation by using our screw-type unloaders would save the global industry up to US$400 million every year. This figure is supported by real world experience and monitored tests that consistently confirm the

AWJ 2019

extremely low level of fines resulting from discharge using our screw-type unloaders.

Efficient, gentle unloading can make the difference between success and failure in marginal cases; a number of smelters have closed because high energy consumption made their operations unviable.

Cutting waste and protecting the environment Reducing energy costs is not the only way in which the industry can benefit from screwtype unloaders. Another discharge technology in widespread use is the grab crane; the downside in this case is the high level of spillage and dust generation. Based on

Further savings are made because there is a negligible amount of cleaning when using a Bruks Siwertell unloader. Working conditions are greatly improved and the impact on the port and surrounding areas is negligible.

Clean operations are vital for importers with facilities close to centres of population and commerce who are finding it difficult to meet increasingly stringent environmental regulations.

Performance promises guaranteed We are confident that the global aluminium production industry could save hundreds of millions of US dollars if it made the move from traditional discharge systems to totally enclosed screw-type unloaders.

The savings are delivered in a number of ways, related to the nature, value and processing requirements of alumina. But in all instances, it is the performance of the screw-type unloader â&#x20AC;&#x201C; when compared to the alternatives â&#x20AC;&#x201C; that delivers the results.

MATERIALS AND HANDLING 45

substantial guarantees related both to the performance of the unloader as well as the degradation of the bulk material, what have you got to lose?

Continuous, totally-enclosed, screwtype unloader technology Bruks Siwertell offers a range of continuous screw-type unloaders; the largest models deliver some of the highest discharge capacities in the world. They can handle a wide variety of dry bulk materials and are available in electric and diesel-driven versions. With the exception of its trailer-based road mobile unloaders, all versions are custom built to suit the customer’s requirements.

Based on the principles of the Archimedes Screw, the Bruks Siwertell continuous screwtype unloader is effectively a positive displacement pump, picking-up material from below the cargo surface in the ship’s hold. The pump consists of an auger contained within a tight-fitting cylinder. The blades of the auger create individual pockets within the cylinder wall.

As the auger begins to rotate, the inlet feeder scoops-up material which is progressively transferred along the screw, pocket by pocket, while the inlet feeder continues to scoop up bulk material. This process soon creates a continuous discharge flow that is maintained at a virtually constant rate until the hold is almost empty.

A key feature of Bruks Siwertell’s screw conveyor technology is the unique inlet feeder that ensures effective filling of the vertical screw conveyor.

The counter-rotating inlet feeder is designed to pick up material from below the cargo surface, minimising

dust creation. The position of the inlet feeder is controlled by the operator by means of travelling, slewing, luffing and pendulum motions. This allows the use of the layer-by layer discharge technique that virtually eliminates the risk of cargo avalanches within the hold. The design of the feeder ensures efficient pick-up of compacted materials and cargoes with hard surface crusts.

Bruks Siwertell unloaders typically discharge into totally enclosed Bruks Siwertell conveying systems. These too are designed to eliminate spillage, minimise dust emissions and protect the cargo from the elements by means of a travelling transfer trolley with belt lifting arrangement. The jetty conveyor is fitted with a rubber cover belt which is raised by the transfer trolley to allow the gantry conveyor access for discharging the cargo on the receiving conveyor in a covered, dust-free manner.

Bruks Siwertell unloaders benefit from optional systems including wireless control, anticollision functions and remote monitoring and fault diagnosis.

Semi-automatic discharge is available through a programme that learns from tracking experienced human operators.

Customers benefit from Bruks Siwertell’s global support network and can take advantage of flexible, modular maintenance contracts. As trading requirements change, Bruks Siwertell can offer upgrades, modifications and relocation services to ensure the customer continues to obtain a good return on its investment.

The recycling bonus that keeps on giving Unlike many metals and other materials, aluminium can be recycled indefinitely without suffering any changes to its physical properties.

This quality is becoming increasingly important in a world seeking sustainability in its materials and industrial processes. In addition to conserving finite resources, recycling aluminium requires only five percent of the energy needed for primary aluminium production. About 75 percent of the world’s historic aluminium production is still in use.

Each time a unit of aluminium is melted and reused, the more energy efficient it becomes, mitigating the high energy demands and inevitable degree of pollution associated with primary production.

While some aluminium products such as cans have a very short existence, many others have an extremely long life. Aircraft, cars and buildings lock up their significant aluminium content for years or even decades.

As the global stock of aluminium steadily increases and scrap recovery techniques and systems improve, the balance between primary production and recycling will move in favour of recycled product, reducing energy demands and pollution.

Juha Huovilainen, Bruks Siwertell Sales Director

46 MATERIALS AND HANDLING

AWJ 2019

Increase your profits with intelligent solutions Your challenge may be to invest in a cement handling solution that ensures profitable and sustainable growth for your business. Our expertise is to provide just that solution. Thanks to totally-enclosed conveyors, the operation with Siwertell equipment is free from dust and spillage.

• Ship unloading • Ship loading • Conveying

• Stacking & Reclaming • Truck unloading • Chipping

• Milling • Screening • Wood residue processing

bruks-siwertell.com Part of Bruks Siwertell Group

AWJ 2019

PRIMARY SMELTING MATERIALS AND AND PROCESSES HANDLING 47

FIVES TECH + FIVES TEAM

THE COMBINATION OF A WIDE RANGE OF SERVICES WITH A NETWORK OF LOCAL EXPERTS IN THE ALUMINIUM INDUSTRY FIVES’ EXPERTS ARE COMMITTED TO ASSISTING CUSTOMERS in both improving their plant’s performance and availability, and ensuring the long-term sustainability of their installations.

Thanks to highly-skilled and proactive Aluminium teams based in Australia, Bahrain, Canada, Europe, India, Russia, South Africa and UA E, Fives provides an efficient response to your daily needs. From preventive maintenance, modernization, inspection, repair to audit and training, Fives has a unique technical expertise coming from its experience as both equipment designer and supplier, and global solution integrator.

Fives aims at enhancing production on a long-term basis while ensuring operators’ safety and equipment reliability.

www.fivesgroup.com Aluminium 48

AWJ 2019