Pulping liquors

Oversized chips are sometimes sHced to control thickness in a slicing rechipper. The uniform thickness results in more even penetration of pulping liquors and therefore less screen rejects in the resultant pulp. 

Tall oil rosin is obtained from crude tall oil obtained from the Kraft (sulphate) pulping of various coniferous trees in the paper manufacturing industry. During the Kraft pulping process the fatty acids and the resin acids from the coniferous wood are saponified by the alkaline medium. On concentration of the resulting pulping liquor, the sodium soap of these mixed acids rises to the surface from where they are skimmed out. By acidification of this material with sulphuric acid, the crude tall oil is obtained. Fractional steam distillation of the crude tall oil allows the separation of the tall oil fatty acids and the tall oil rosins [21]. 

Kuban P. and Karlberg B., On-line monitoring of kraft pulping liquors with a valveless flow injection-capillary electrophoresis system, Anal. Chim. Acta, 404, 19, 2000. 

Pulping liquors. Pulping liquor, also called black liquor, is a corrosive material used to dissolve wood chips for the manufacturing of paper and other materials. To promote waste minimization and recycling, U.S. EPA excluded pulping liquors from the definition of solid waste if they are reclaimed in a recovery furnace and then reused in the pulping process. If the liquors are recycled in another way, or are accumulated speculatively, they are not excluded. 

The addition of anthraquinone (a chemical catalyst produced from coal tar) to the pulping liquor has been shown to speed up the kraft pulping reaction and increase yield by protecting cellulose fibers from degradation. The anthraquinone accelerates the fragmentation of lignin, allowing it to be... 

Spent pulping liquor spills from pulp processing areas... 

Kellner process are unbalanced, and for the regeneration of waste pulping liquors in the manufacture of pulp and paper by the Kraft process. See also Lowig. 

In chemical pulping, a significant part of the hemicelluloses is dissolved from the fibres into the pulping liquor. The rest remains in the fibre or is adsorbed into it, significantly affecting the properties of the cellulose fibres or paper produced... 

Interferences such as bubbles, undissolved particles, and color do not affect the resulting refractive index, making this method quite suitable for opaque, highly viscous, and highly colored substances such as milk and pulp liquor. 

Several pulp mills now use AQ on a commercial basis (Oloman 1996). According to Oloman, the addition of AQ to pulping liquor in an amount of 1 kg AQ per ton of pulp increases the pulp yield from starting woods by abont 1%. This complementary action gives rise to increased revenue of about 2 million per year for a pnlp mill with a daily prodnctivity of 10001. 

Wood chip digestion, spent pulping liquor Water High BOD, color, may contain... 

Wood chips are processed in mild chemical liquor and subjected to mechanical refining using disc refiners. Semichemical pulping liquors have variable composition ranging from sodium hydroxide alone, alkaline sulfite (sodium sulfite - - sodium carbonate), mixtures of sodium hydroxide and sodium carbonate, to Kraft green or white liquors [3]. Sodium sulfite/ sodium carbonate liquor is most commonly used and the pulp product obtained thereafter is referred to as neutral sulfite semichemical (NSSC) pulp. 

Kraft pulping involves the cooking of wood chips at 340-350°F and 100-135 psi in liquor that contains sodium hydroxide, sodium sulfide, and sodium carbonate. This process promotes cleavage of the various ether bonds in lignin and the degradative products so formed dissolve in alkaline pulping liquor. The Kraft process normally incorporates several steps to recover chemicals from the spent black liquor [3]. 

COMPOSITION OF SPENT PULPING LIQUORS 10.4.1 Kraft Pulping Liquors (Black Liquors)... 

Table 5 Composition of Ammonia, Sodium, Magnesium, and Calcium Base Sulfite Pulping Liquors...

Thermomechanical Pulp (TMP), CTMP, and Semichemical Pulping Liquors... 

Table 6 Composition of Spent NSSC Pulping Liquor...

The free sulfur dioxide in the sulfite pulping liquor promotes hydrolysis of the more easily hydrolyzable constituents of wood. A wood such as spruce, which contains 70.1% carbohydrate substances, of which 85.3% are potentially fermentable, gives a 50% yield of a pulp containing 97.7% carbohydrate, of which about 80% is fermentable. The... 

The vendor indicates the technology can treat waste streams containing solvents, petroleum distillates, chlorinated solvents, pesticides and herbicides, as well as phenolic wastes, pulping liquors, municipal sewage, and industrial sludges. 

In the United States, up to about 4 x 1015 Btu/yr of biofuels are consumed for electricity generation, raising process heat, and domestic heat. Furthermore, much of the eneigy needs of many nations are met by biofuels, including wood and wood waste, spent pulping liquors, bagasse, and municipal waste. Some use is also made of dried com cobs, rice hulls, and a wide variety of agricultural wastes used in niche applications. 

This lignin-based bio-adhesive can be applied under conventional pressing conditions. The resulting particle boards meet German performance standards without emission of harmful vapors. An added advantage is the total utilization of lignin from spent pulp liquor. 

Preliminary Oxidation with Cupric Oxide and Alkali. This first oxidation study under conditions used previously for evaluating ligno-sulfonate solutions (//) used the fractionation procedure developed recently for analyzing spent pulping liquors (75, 16). This procedure was used with little change for most of the oxidation experiments here. 

As discussed in Section 1.2.2 the bubble shapes in fairly dry foams and froths (4 gas > 0.83, approximately) are not spheres or distorted spheres, but polyhedrons. In practice there will be distributions of both gas-cell sizes and shapes. In addition to the gas bubbles, froth contains the floated particles, pulp liquor, and a fraction of (hydrophilic) particles that did not float due to bubble attachment, but which were mechanically entrained in the froth. The pulp liquor and these latter particles all have to be allowed to drain back out of the froth. The rate of this drainage will be greatest at the froth-pulp interface (i.e., the bottom of the froth layer) and slowest near the top of the froth layer. Froth drainage equations are discussed elsewhere [53]. The froth needs to be a stable enough foam that some time can be allowed for these drainage processes, and also so that the upper layer(s) of the froth can be swept out of the flotation cell. On the other hand, the froth should not be too stable as a foam so that it will break easily after collection. In addition to the role of the frother, froth stability is also promoted by increasing liquid viscosity. 

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