From the sulfite pulping process

Tall Oil Fatty acids and some unsaponifiable material obtained as a major byproduct from the sulfite-pulping process of wood. 

In contrast, the lignins from the sulfite pulping processes are readily available in commercial quantities from several pulp producers in different countries. More than enough is available annually to replace the entire output of synthetic phenol. In aqueous solution, the price of these lignin sulfonates can be as low as 3 cents a pound on a dry basis. The spray-dried forms sell for about 15 cents a pound (>/). Clearly, the process of spray drying is not inexpensive. 

Lignins are most usually employed as various types of sodium lig-nosulfonate and are products of sulfite pulping. (Kraft lignins from the Kraft pulping process are also available.) They are used as dispersants, binders, sequestrants, and emulsifiers. Sodium lignosulfonate product variables include color, MW, and the degree of carboxylation and sulfonation on the lignin backbone. 

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. 

L., gained from the Kraft pulping process (- paper), is sulfonated after isolation from the black liquor with sodium sulfite at 150-200 °C or sulfo-methylated in the presence of formaldehyde below 100 °C. 

The use of the lignin fraction is much more cumbersome currently the best-known chemical of a real commercial importance is vanillin, which is obtained by oxidation of the black liquor. Another example is a product called spray-dried lignosulfonate (as sodium salt) obtained from the older, acidic sulfite pulping process. It is sold as a commercial product primarily as a concrete additive for enhanced strength. Since the cement industry is one of the big contributors of carbon dioxide emissions (due to the production of calcium oxide from calcium carbonate), the use of this renewable, wood-derived product not only is fossil-carbon neutral in itself but also reduces carbon dioxide emission due to the diminished need for cement in large infrastructures made of concrete. 

Attisholz A process for recovering valuable waste products from the sulfite process for making wood pulp. This includes methanol, cymenes, and furfural. Developed in Switzerland. 

The paper pulping industry is reportedly not, in total, a very large emitter of sulfur oxides, although individual plants may present local problems. Kraft mills emit more malodorous reduced sulfur compounds, whereas sulfite mills are more important as emitters of sulfur dioxide. The pulping processes (particularly sulfite) are most interesting because the chemical recovery cycles use basic chemistry that could well be applied to recovery of sulfur dioxide and sulfur from the flue and process waste gases of other types of sources. 

Feed Materials. The spent pulping liquors used were from pulp mills using various sulfite pulping processes. To facilitate data presentation, the following code is used for designating the liquors used as feed materials. 

Figure 8.12 Furfural/acetic acid extraction plant to treat the condensate from Lenzing s sulfite pulping process (extraction efficiency -80-90%). ...

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