Sulfate pulping

Terpenes, specifically monoterpenes, are naturally occurring monomers that are usually obtained as by-products of the paper and citms industries. Monoterpenes that are typically employed in hydrocarbon resins are shown in Figure 2. Optically active tf-limonene is obtained from various natural oils, particularly citms oils (81). a and P-pinenes are obtained from sulfate turpentine produced in the kraft (sulfate) pulping process. Southeastern U.S. sulfate turpentine contains approximately 60—70 wt % a-pinene and 20—25 wt % P-pinene (see Terpenoids). Dipentene, which is a complex mixture of if,/-Hmonene, a- and P-pheUandrene, a- and y-terpinene, and terpinolene, is also obtained from the processing of sulfate Hquor (82). 

The most commonly used reinforcement for high pressure decorative and industrial laminates is paper (qv). The strong substrate layers, or filler, are kraft paper. Kraft is a brown paper made from a sulfate pulp process (8). It consists of both short cellulose fibers from hardwoods and long fibers from conifers. The long fibers impart most of the wet strength required for resin saturation processes. 

Trees, especially conifers, contain tall oils. Tall oil is not isolated dkecfly tall oil fatty acids are isolated from the soaps generated as a by-product of the sulfate pulping process for making paper. Refined tall oil fatty acids are obtained by acidification of the soaps, followed by fractional distillation to separate the fatty acids from the rosin acids and terpene hydrocarbons that also are present in the cmde tall oil fatty acids (see Carboxylic acids Fatty ACIDS FROMTALL OIL). 

Typical applications in the chemical field (Beaver, op. cit.) include detarring of manufactured gas, removal of acid mist and impurities in contact sulfuric acid plants, recovery of phosphoric acid mists, removal of dusts in gases from roasters, sintering machines, calciners, cement and lime Idlns, blast furnaces, carbon-black furnaces, regenerators on fluid-catalyst units, chemical-recoveiy furnaces in soda and sulfate pulp mills, and gypsum kettles. Figure 17-74 shows a vertical-flow steel-plate-type precipitator similar to a type used for catalyst-dust collection in certain fluid-catalyst plants. 

Gierer, J. Ljunggren, S. The reactions of lignin during sulfate pulping. Part 17. Kinetic treatment of the formation and competing reactions of quinone methide intermediates. Sven. Papperstidn. 1979, 82, 503-512. 

Treatment of Cellulose" plus Additives under Sulfate-Pulping Conditions... 

The current uses of sodium sulfate include detergents (45%, as a phosphate substitute), textiles (18%), kraft sulfate pulping (13%), and glass (10%). 

After the chemical treatment, the pulped wood is removed, washed, and screened. Unbleached, brown-colored paper is made directly for this material. Most whitened or bleached paper is made by the treatment of the pulp with chlorine, chlorine dioxide, hypochlorite, and/or alkaline extraction. In general, sulfate-pulped paper is darker and requires more bleaching and alkaline extraction to give a white pulp. 

Trees, especially conifers, contain tall oils. Tall oil is not isolated directly tall oil fatty acids arc isolated from the soaps generated as byproducts of the sulfate pulping process for making paper. 

Fig. 1-15. Ballooning of a sulfate pulp fiber (Pinus sylvestris). Note the ribbonlike, unrolled primary wall (P) and the swollen secondary wall. S, is the swollen outer layer of the secondary wall, under which the microfibrils of the middle layer, nearly parallel to fiber axis, are dimly visible. S3 is the inner layer ot the secondary wall (llvessalo-Pfaffli, 1977).

Ray cells in unbleached sulfite and sulfate pulps (weight %) Distributed on 8 6... 

F g- 7-32. Hemicellulose losses during sulfate pulping of pine wood (Sjostrom, 1977). 1977. TAPPI. Reprinted from Tappi 60(9), p. 152, with permission. 

Simonson, R. (1963). The hemicellulose in the sulfate pulping process, Part 1, The isolation of hemicellulose fractions from pine sulfate cooking liquors. Sven. Papperstidn. 66, 839-845. 

Experiments with wood fiber pulps by the National Bureau of Standards have shown that the purer the pulp (higher the a-cellulose content) the more permanent it is. Moreover, as the a-cellulose content in these pulps approaches that of the a-cellulose content of rag fibers, the permanence of these fibers likewise approaches that of rag fiber. Therefore, paper made from sulfite pulps which have a high a-cellulose content would have better permanency properties than sulfate pulps provided that they are carefully made. 

Calcium Lignosulfonate occurs as a brown, amorphous polymer. It is obtained from the spent sulfite and sulfate pulping liquor of wood or from the sulfate (kraft) pulping process. It may contain up to 30% reducing sugars. It is soluble in water, but not in any of the common organic solvents. The pH of a 1 100 aqueous solution is between approximately 3 and 11. 

Kleinert TN, Joyce CS (1957a) Short wavelength absorption of various lignins and related substances IV Lignin determination in sulfate pulping liquors Pulp Pap Mag Can 58(11) 147-152... 

Gierer J, Lindeberg O (1980) Reactions of lignin during sulfate pulping Part XIX Isolation and identification of new dimers from a spent sulfate liquor Acta Chem Scand B 34... 

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