Extractives from black liquors

WaUmo H. Lignin extraction from black liquor - precipitation,filtration and washing [Doctoral thesis]. Gothenburg, Sweden Chalmers University ofTechnology, Forest Products and Chemical Engineering. 2008.73 p. 

He describes the many advantages of using CO2 as the extractant in this application, e.g., low cost, ease of separation from the extract, nonflammability, etc. these advantageous features, however, aren t going to make the concept of extracting lignin from black liquor using CO2 work. 

Baklien A 1960 The effect of extractives on black liquor from eucalypt pulping. Appita 14 5-17... 

Black liquor is 13 to 17% strength, rinsed extract from washed and cooked woodchip pulp, produced in the Kraft pulping process. This... 

In the ALCELL process, conventional hardwood chips are cooked in batch extractors with an aqueous ethanol liquor at appropriate temperatures, pH, and time. In the process lignin, hemicellulose and other various components of wood are extracted from the chips into the aqueous ethanol forming a black liquor. 

Kraft Lignin. A softwood kraft lignin (KL) was isolated from a partly evaporated, industrial kraft black liquor by precipitation through the addition of dilute sulfuric acid as described elsewhere (7). The lignin was thereafter fractionated by successive extraction with organic solvents (7). The KL fraction used in the present investigation was the second of five fractions obtained (propanol soluble - methylene chloride insoluble). 

Curare is the arrow poison of the South American Indians, and it may contain as many as 30 different plant ingredients, which may vary widely from tribe to tribe according to local custom. Curare is prepared in the rain forests of the Amazon and Orinoco, and represents the crude dried extract from the bark and stems of various plants. The young bark is scraped off, pounded, and the fibrous mass percolated with water in a leaf funnel. The liquor so obtained is then concentrated by evaporation over a fire. Further vegetable material may be added to make the preparation more glutinous so that it will stick to the arrows or darts. The product is dark brown or black, and tarlike. 

Yields of 50% and reduced energy consumption have been achieved by a history of innovation. Such innovation has included the Tomlinson black liquor recovery boiler, the Kamyr continuous digester and associated diffusion washer, multiple-effect evaporators, and low-odor concentrators. Economic advantages also have been gained by the development of systems for recovering extractives such as tall oil, fatty acids, and resin from the pulping liquor for sale as naval stores. Future innovations may focus on the lime kiln and other related systems. 

Kontturi AK, Sundholm G (1986) The extraction and fractionation of lignosulfonates with long chain aliphatic amines Acta Chem Scand 40 121-125 Wada S, Iwamida T, Iijima R, Yabe K (1962) Fractional precipitation of kraft black liquor from spruce wood Chem High Polymers (Kabunshi Kagaku) 19 699-705... 

The recovery of phenol, cresols, and guaiacol by extraction from kraft pulping process black liquor. 

Liquors from Neutral Semichemical Pulping and from Kraft Pulping. In making neutral sulfite semichemical pulp, the black liquors may have about 10 parts of water to 1 part of total solids, of which about one-third is sodium acetate and sodium formate. After evaporation to about 1 part solids to 1 part water, sulfuric acid is added to the concentrate to free the acetic and formic acids. When the concentrate is extracted with acetone, the mixed acids are obtained, the acetone is separated for recycle, and the acids are concentrated and refined. The raffinate is stripped and is passed to the usual furnace to be burned for recovery of the inorganic salt values. This process gives a smelt of sodium sulfate, which may be used in the kraft process as chemical makeup. The loss of the fuel value of the acetic and formic acids is practically negligible. 

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). 

Sometimes known as the sulfate process, since the sulfur is added as sodium sulfate. It is then reduced to S ° by burning with the evaporated black liquor (lignin and carbohydrate fragments from a previous cook) in an insufficient supply of air. Water extraction yields green liquor , a solution of (largely) sodium sulfide and sodium carbonate and which is treated with slaked lime [Ca(OH)2j. Insoluble calcium carbonate precipitates and the resulting solution of sodium hydroxide and sulfide ( white liquor ) is used for a new cook. 

We were very critical of a previous patent on the same subject of extracting valuable lignin and other extractable components from kraft black liquor in the first edition of our book (see page 460 U. S. 4,493,797). As in the first patent, the use of fluidized beds and catalytic reaction to convert the lignin dissolved in the supercritical... 

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