Fibre continued plant

BP Chemicals developed a batch process capable of producing 100 kg of acetylated fibre per day, and a larger batch process, capable of producing 1 tonne per day, was to be constructed by Depac Engineering Ltd. Sheen (1992) also reported on an analysis of the costs for batch and continuous plants producing 10 000 tonnes of acetylated fibre per year at a WPG of 20 %. An essential part of the process to ensure commercial viability was the recovery of by-product acetic acid. The calculated costs in pounds sterling, based on fully dried fibre and in 1992 prices, are shown in Table 8.3. 

Dietary fibre, which comprises all the non-digestible structural carbohydrates of plant cell walls and any associate lignin, provides a further example of a complex food-borne factor which cannot be classified as a nutrient, and which continues to generate debate over such issues as definition and analytical techniques. However, whatever the unresolved complexities, dietary fibre has a lengthy history and had proved itself eminently suitable as a component of functional food products long before the term was even coined. 

The capital cost of the batch acetylation plant was calculated at 12 million and that of the continuous process plant at 5.5 million. It was assumed that the acetylation facility would be integrated with a traditional fibreboard plant, so that fibre production and drying costs were not included in the analysis. The analysis showed that wood fibre could be acetylated to a WPG of 20 % for a cost of 562 per tonne in a batch process and 384 per tonne in a continuous process. BP subsequently lost interest in the wood acetylation process and sold the pilot plant. 

Finally, one of the first continuous ion-exchange plants installed used a weak-acid resin to recover copper from rayon-fibre spinning solutions. In the Bemberg or copper(II) ammonium process,357 the spinning takes place in an addic copper sulfate solution, and the fibre is then washed in ammonia solution. The wash water contains as much as 30% of the copper required for the spinning operation and its recovery is important in economic and environmental terms. The copper is extracted as the cationic amine complex by the weak-acid resin, and is then stripped from the resin with the acidic spinning solution. Zinc is recovered in a similar manner from vicrose rayon-spinning operations. 

Despite the general move towards use of fossil hydrocarbon feedstocks, some plant-derived materials have continued to provide economic or technical benefits that ensure they remain the preferred source of raw materials for industry. For example, cotton still accounts for 38% of all textile production due to its airflow- and temperature-regulating capabilities, which are difficult or costly to replicate with man-made fibres. Linseed oil remains a key feedstock in surface coating and linoleum flooring applications. Plant oils are still widely used in the oleochemicals sector, where coconut and palm oils are widely used in detergent... 

The overall picture is of the wood-based panels sector continuing to grow as products are developed that meet new customer requirements. The processes have demonstrated an adaptability to different fibre sources, both in form and in species that has allowed plants to be established in most parts of the world, primarily to meet local demand, but also with a significant export component to those areas where fibre supplies are fully committed. 

Natural fibres can be obtained from various parts of a plant, as shown in Table 13.2. Natural fibres can be continuous fibres, short fibres, whiskers or particles, as shown in Figure 13.4. Types of polymer composite based on shape and structure are divided into particle, fibre and structural. 

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