Sulfite pulping cooking liquor

Paper Products. Paper (qv) products account for about 2% of sulfur demand. The laigest single segment of demand is in the manufacture of wood pulp by the sulfite process (see Pulp). In this process, the main sulfur intermediate is sulfur dioxide, which is generally produced at the plant site by burning elemental sulfur. Some sulfur dioxide, however, is produced as a by-product at smelter operations, purified and liquefied, and shipped to the pulp mills. The sulfur dioxide is converted to sulfiirous acid, and the salt of this acid is a principal component of the cooking liquor for the sulfite process. 

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. 

Condensation reactions of lignin have been mentioned 22) in connection with sulfite pulping as being responsible for color formation. However, most of the likely condensation reactions occurring during a kraft cook do not lead directly to chromophore formation. One potential condensation reaction which would give a chromophore is the formation of a chalcone (XIX) from vanillin and acetoguaiacone, both of which have been isolated by Enkvist 12) from black liquor. 

There are several modifications of the sulfite method which are designated according to the pH of the cooking liquor (Table 7-1). For the production of chemical pulps, delignification is allowed to proceed until most of the lignin in the middle lamella is removed after which the fibers can be readily separated from each other. Semichemical pulps are often produced by the neutral sodium sulfite method followed by mechanical fiberization of the partially delignified wood. 

Sulfite Process. The sulfite process uses a cooking liquor of sulfurous acid and a salt of the acid. Although calcium was the most widely used base at one time, it has been supplanted by sodium, magnesium, and ammonia. Lignin will react with the bisulfite ion (HSO3") under acidic conditions to form lignosulfonates that are soluble in water. For many years this was the preferred process because it produced pulps of light color that could easily be bleached, it used cheap chemicals in fairly limited amounts so that no recovery was necessary, and it was a relatively simple process to operate. 

Kleinert TN, Joyce CS (1957b) Short wavelength absorption of various lignins and related substances III The flow-micro cuvette for continuous measurement of lignin concentration in sulfite cooking liquors Pulp Pap Mag Can 58(7) 215-219 Kolboe S, Ellefsen O (1962) Infrared investigations of lignin A discussion of some recent results Tappi 45 163-166... 

Fourdrinier machine—The machine that forms paper from pulp, named after the English family that financed its development in the early 1 800s. Furnish—Specific combination of pulp and other ingredients used to make a particular kind of paper. Kraft process—process in which sodium sulfate is reduced by heating with carbonaceous matter in a furnace to form sodium sulfide, which is then used in a water solution with sodium hydroxide as a cooking liquor. The wood pulp is then cooked under pressure and at high temperatures. The kraft process, also known as the sulfate process, has a less corrosive influence on iron and steel than the sulfite process. 

Sulfite process—process in which sulfur dioxide is passed through calcium carbonate to form calcium bisulfite in an excess of sulphurous acid as the cooking liquor. The wood pulp is then cooked under pressure at high temperatures. 

Paper and pulp mill condensate - 189, 206 Paper and pulp mill gas, noncondensable 203 Paper, bleach solutions - 541, 693, 694, 724 Paper, groundwood pulp stocks - 541 Paper machine - 204 Paper mill liquor - 204, 206, 539, 724 Paper, neutral sulfite Cooking liquor - 541 Pulp stocks - 542 Spent liquor - 542 Paper, paperboard waste 542 Paper, parchmentizing - 542 Paper pulp, bleached - 694 Paper pulp slurry 694 Paper, sizing solution - 543 Paper stock 694 Paper, white water Acid - 543 Groundwood - 543 Neutral sulfite - 543 Newsprint - 543 Paperboard 544 Soda - 544 Sulfate - 544 Peracetic acid - 30 Parachloride 230... 

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