In the summer of 2013, the world’s largest the polysulphide digestion method. Metsä
single-line softwood pulp mill will begin using Fibre’s new product will save energy and improve the pulp’s paper-making properties. TEXT / PETJA PARTANEN, PHOTOS / METSÄ GROUP
order to benefit the environment and make the most of scarce raw material, in summer 2013 the Joutseno mill will take a giant leap forward with the introduction of a brand new cooking process. The improved technical properties of the cellulose will also provide cost savings for paper manufacturers. “The new production method needs less wood per tonne of end product,” explains Henrik Söderström, Vice President, Mill Manager at Joutseno mill. “The polysulphide digestion method improves the tensile strength and bonding properties of the fibres produced, while the process itself requires less refining energy,” points out Söderström. “Metsä Fibre’s new pulp product will offer unprecedented potential for our customers,” adds Tom Nickull, Key Accounts & Vice President, Technical Customer Service at Metsä Fibre. “This is a huge leap forward!” says an excited Kari Kovasin, D.Sc. (Tech.), one of the developers of Joutseno’s new cooking process. In his opinion, the polysulphide digestion method is a technical improvement similar to when the bleach-
ECHO TECH
ing process was completely changed in the beginning of 1990s and chlorine chemicals were removed from the pulp bleaching process.
Significant energy savings The new digestion method will deliver immediate cost savings for all Joutseno pulp buyers. Before transfer to the paper machine, pulp must be refined. The refining process is used to adjust the paper-making pulp properties as desired. “The new pulp composition will reduce the need for refining and therefore the amount of electricity used,” says Nickull. As a result of the new cooking process, the pulp strength properties, such as tensile strength, tensile stiffness and internal bond strength, will improve by about 5–10 per cent. Improved strength properties can be of benefit in many different ways, explains Nickull. “The improved tensile strength is exploitable either by improving the end-product tensile strength or replacing the softwood pulp with a cheaper raw material, while keeping the end-product properties unchanged.” This new type of softwood pulp may provide tis-
PAGE 25