63
The 1994 TAPPI pulping conference
Ir. Gertjan van Roekel, Jr.
ATO-DLO Agrotechnology, P.O. Box 17, 6700 AA Wageningen, The
Netherlands.
Phone: +31 8370 75327, Fax: +31 8370 12260. E-mail: g.j.van.roekel@ato.agro.nl
The scenic San Diego (California, USA) bay was this year's setting for the annual pulping conference of the Technical Association of the Pulp and Paper Industry of the USA.
Eleven hundred engineers, managers, consultants, equipment manufacturers, suppliers and researchers presented and discussed almost 150 papers on various aspects of pulping wood and non-wood fibre sources. Papers covered the whole range of raw material supply, up to the quality of pulps for papermaking, with a clear emphasis on raw material supply and on advances in bleaching technology.
A number of countries are experiencing shortages in wood supply: western Canada, northwest USA, Japan, China, and India. The US and Canada import trees from, for instance, Chile to keep a major economic activity (pulping) going, and Japan is importing Eucalypts from Australia. Especially for Asia, the importance of nonwood fibres to meet the rapidly increasing demand for paper was widely recognised.
Bleaching operations and research for advanced bleaching technology were widely discussed, since the industry is in the process of changing from open bleaching systems using chlorine to closed systems using peroxide, oxygen and ozone with reduced emissions to the environment. Also, the recently developed use of microbial enzymes in the so-called biobleaching process has actually been implemented in large scale pulpmills.
In the non-wood sessions, papers were presented on cultivation, harvest, storage, preprocessing, pulping and papermaking properties of kenaf, bagasse, bamboo, reed canary grass, wheat straw, seedflax and hemp. The heavily crowded “non-wood room” gave the impression that non-wood fibres have gained increased interest.
Several research institutions had come up with new systems and ideas for more efficient pulping methods, with higher yields and less environmental impact.
The process of treating hemp and kenaf fibre with fungi prior to mechanical pulping showed that such a method can prove useful in reducing energy consumption without losing pulp quality. The fungal treatment may be combined with the storage between harvest and processing.
A paper by J.E. Harsveld van der Veen from ATO-DLO in the Netherlands disputed one of the most firm beliefs in fibre pulping: the idea that fibres are held together only by lignin. The paper suggests that not only lignin, but also pectin plays an active role in fibre bonding in plants and trees. Therefore, pulping methods designed for removing lignin are inefficient, and should be modified to remove the complex of both lignin and pectin.
The use of hemp as a papermaking fibre was mentioned a few times in relation to very special and technical applications. Delegates tended to opt for kenaf and seedflax for bulk non-wood papermaking in the US. Seedflax is a fibre very much comparable to hemp, and actually in use as a specific cigarette paper. It is available in huge quantities in Canada, virtually for free, since it is a byproduct of linseed oil production. Kenaf is grown in the southern US states, and seems to do very well. It is preferred over hemp for non-wood “tree-free” paper production in the US, because of the prohibition of hemp cultivation.
The pulping industry is running short of trees. As a result, woodpulp prices have gone sky-high (+130% in one year). Even with this in mind, the majority of delegates still feel that it will take another thirty years before fibre crops will be grown on a large scale in the western world. The reason is the low cost of bulk transport, and the often government-supported exploitation of wood plantations all over the world. It is still cheaper to ship wood from Chile to Canada than to grow hemp there (although the situation is changing rapidly). When the cost of bulk transportation increases, certain areas will be better off growing their own fibre crops.
Until then, the use of agricultural wastes such as seedflax straw and cereal straw will be encouraged. These materials are available free, and will probably attain a negative cost as they become more and more difficult to dispose of by incineration.
Asian countries like China and India will see continued and increased use of non-wood fibre, but with improved and environmentally cleaner technology. It may well be that the technologies developed in the West will be applied and fine-tuned in the East, until the West starts using nonwood fibre. The only exception in the western world is the market where consumers insist on paper made without cutting trees. The tree-free paper market is expected to grow further, since cutting of primary forests is still going on, even for papermaking, and many consumers are not willing to support deforestation.
For additional information please contact the author.
Next