Pulp Manufacture

The process of pulping, degrading the lignin to a more soluble form so the cellulose fibers can be separated from it, involves some interesting chemistry. The kraft or alkaline sulfate process dominates this part of the industry. Approximately 78% of all pulp is made by the kraft process, 3% 

The organic chemistry of the alkali cleavage of lignin is summarized 

The bisulfide ion present in the kraft process is even a better nucleophile than hydroxide, so when it is present it attacks the quinonemethide intermediate. An episulfide is formed that then hydrolyzes to a thiol-alcohol. 

Basic hydrolysis also lowers the molecular weight of the polysaccharides in wood. Two types of hydrolysis occur, peeling and chain cleavage, as 

After the crude pulp is obtained from the alkaline sulfate process, it must be bleached in stages with elemental chlorine, extracted with sodium hydroxide, and oxidized with calcium hypochlorite, chlorine dioxide, and 

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Pulp Manufacture. Sodium sulfite is utilized in neutral semichemical pulping, acid sulfite pulping, high yield sulfite cooling, and some kraft pulping processes (339). Many pulp mills prepare their own sulfite and recycle as much as possible, but use of merchant sodium sulfite by pulp mills is substantial. Much of the by-product sodium sulfite from resorcinol manufacture goes into pulp appHcations as well as a substantial fraction of the lower assay manufactured sodium sulfite. 

CTO prices are closely tied to the cycles of the U.S. economy and the paper industry. They vary between 120 and 220 per metric ton. In 1995 they were close to 200/t (4). With 50% of pine wood being converted to linerboard valued at 400— 600 per ton, pulp manufacturers do not focus on optimum black Hquor soap recovery, which only amounts of 60—70 kg/1 of southern pine pulp. This soap is converted to 30—35 kg of CTO, worth 6— 7 or less than a Htde over 1% of the pulp value (5). This recovery is only 45% of the CTO available in the pine tree. With more care and higher CTO prices, 10—15 kg of additional CTO could be obtained per ton of pulp (6). 

The paper and pulp industries consume taif/e quantities of Ca(OH)2 and precipitated (as distinct from naturally occurring) CaCOs. The largest application of lime in pulp manufacture is as a causlicizing agent in sulfate (kraft) plants (p. 89). Here the waste NajC solution is reacted with lime to regenerate the caustic soda used in the process ... 

Sulphur dioxide is used as a preservative for beer, wine and meats in the production of sulphites and hydrosulphites in solvent extraction of lubricating oils as a general bleaching agent for oils and foods in sulphite pulp manufacture in the cellulose and paper industries and for disinfection and fumigation. 

Pulp manufacture by stone groundwood, mechanical refiner, thermo-mechanical, chemi-mechanical, or chemi-thermomechanical means for newsprint, coarse papers, tissue, molded fiber products, and fine papers... 

Various technologies and chemicals are used to manufacture pulp, but most pulp manufacturing systems contain the process sequence shown in Table 21.4. Overall, most of the pollutant releases associated with pulp and paper mills occur at the pulping and bleaching stages where the majority of chemical inputs occur. 

McDonough, T. J., Recent Advances in Bleached Chemical Pulp Manufacturing Technology, Part 1 Extended Delignification, Oxygen Delignification, Enzyme Applications, and ECF and TCF Bleaching, Tappi J., 78(3) 55 (1995)... 

The first commercial sulphur dye was discovered accidentally in 1873 by Croissant and BretonniSre who heated lignin-containing organic waste, such as sawdust, with sodium polysulphide at about 300 °C the product was sold under the name Cachou de Laval [52]. Even today an equivalent dye (Cl Sulphur Brown 1) is derived from lignin sulphonate, which is readily available from waste liquors from wood pulp manufacture. The real pioneer of sulphur dyes was Vidal, the first chemist to obtain dyes of this type from specific organic compounds. In particular, Sulphur Black T (Cl Sulphur Black 1) was made from 2,4-dinitrophenol in 1899. At the turn of the century many of the intermediates available were subjected to sulphurisation (thionation), that is, treatment with sulphur, sodium sulphide or sodium polysulphide to introduce sulphur linkages. 

Uses Copolymerized with methyl acrylate, methyl methacrylate, vinyl acetate, vinyl chloride, or 1,1-dichloroethylene to produce acrylic and modacrylic fibers and high-strength fibers ABS (acrylonitrile-butadiene-styrene) and acrylonitrile-styrene copolymers nitrile rubber cyano-ethylation of cotton synthetic soil block (acrylonitrile polymerized in wood pulp) manufacture of adhesives organic synthesis grain fumigant pesticide monomer for a semi-conductive polymer that can be used similar to inorganic oxide catalysts in dehydrogenation of tert-butyl alcohol to isobutylene and water pharmaceuticals antioxidants dyes and surfactants. 

Peracetic acid or its anion, produced in situ from A, A, A, A -tetraacetylethylenediamine, in the presence of hydrogen peroxide, in slightly alkaline solution (equation 14), is an effective bleaching agent used in pulp manufacture and laundering. Household washing solution formulations contain perborate and activators that produce peracetic acid of bleaching effect . ... 

Explosion Unit Operation (See also "Explosive Disintegration"). The explosion technique has been applied successfully for the modification of substances and for separation of components, as well as for size reduction of materials. This method has been used in rubber reclaiming, wood pulping, manufacture of fiber board, pulverization of minerals and coal and finally for the prepn of puffed cereals... 

Lignin utilization studies have been conducted in several fields. However, no practical, commercial process has yet emerged for the manufacture of lignin-based polymeric materials. This is undoubtedly related to such factors as product inhomogeneity, reactivity differences, and also with lack of familiarity with this type of raw material. It should be also stressed that lignins are only by-products from pulp manufacture. However, the utilization of lignins in polymeric materials seems to be possible. 

MARATHON-HOWARD PROCESS. A treatment of waste sulfite liquor from sulfite pulp manufacture In recover chemicals and reduce steam pollution. The waste sulfite is treated with line and precipitates. (I) calcium sulfite for use in preparing fresh cooking acid for the sulfite pulp process, and 121 a basic calcium salt tif ligmn sulfonic acid (lignin sullYmalesi that can be pressed and used as a fuel of used as raw- material for vanillin, lignin plasties, and other chemicals. The remaining liquor with its BOD reduced X() ( is the effluent. 

Cardboard box and paper products (paper and pulp manufacture excluded)... 

Fiber Pulp Manufacturing Cement Concrete Manufacturing Sponge Iron Manufacturing Chemicals Manufacturing... 

AgroResin is a biodegradable packaging material from by-products of the palm oil industry. It can also be made from agricultural fibres, such as wheat straw. It is compatible with existing moulded pulp manufacturing processes. AgroResin has received Din-Certco certification for products made of compostable materials (DIN EN 13432 2000-12). 

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