Black liquor, kraft composition

Gum turpentine is obtained from wounding living trees to get an exudate containing turpentine and rosin. Turpentine is separated from the rosin by continuous steam distillation and further fractionation. Wood turpentine comes from the extraction of stumps of pine trees using naphtha, and subsequent separation of rosin and turpentine by fractional distillation. Tail-oil turpentine is a byproduct of the Kraft sulphate paper manufacture. Terpenes are isolated from the sulphate terpentine and separated from the black digestion liquor. The composition of turpentine oils depends on its source, although a-pinene and p-pinene are the major components. 

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

Table 4 shows the typical ranges of black liquor constituents and characteristics of Kraft evaporator condensates. The composition of liquors may vary significantly, depending upon the type of raw material used. Inorganic constiments in black liquor are sodium hydroxide, sodium sulfate, sodium thiosulfate, sodium sulfide, sodium carbonate, and sodium chloride [11]. 

Cortinas et al. [89] eliminated colloidal suspended material (pitch) from kraft black liquors and partly recycled the liquor to the digester to reduce the consumption of chemicals. The colloidal pitch is formed by wood extractives. In particular, compounds such as waxes, sterols, and sterol esters that do not form soluble salts or dissolve during cooking form colloidal particles. The concentrated liquors (14%-15% solids) were filtered at high temperature using a 0.2 xm alumina membrane (USF Shumacher, Crailsheim, Germany). The pitch was almost completely retained (>99.9%), but the flux was sensitive to the black liquor composition and sometimes decreased to less than 100 L/(m h). 

Table 3A.3 Typical composition of kraft black liquors (% of total dry matter) Component Pine Birch...

Typical compositions for softwood and hardwood kraft black liquors are shown in Table 9. Most commercial kraft lignins are sulfonated kraft lignins or lignin amines. A few nonsulfonated products are, however, available. 

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