SU1043215A1 - Method of preparing alkaline digesting composition for making cellulose-containing fibrous semifinished product - Google Patents

Abstract

Method of preparation of alkaline varnish solution for making cellulose containing liquor, green liquor recovery characterized in that, in order to increase the efficiency of the process and improve the quality of the cooking solution, the white sludge is washed biologically purified waste water with a concentration of excess (O activated sludge 3-12 g / l. (O

Description

FIELD OF THE INVENTION The invention relates to cellulose and paper industry and the industry; is used in the production of pulp fiber semi-finished products. A known method of preparing an alkaline cooking solution by regenerating spent black liquor after sulphate cooking to produce white liquor consists in burning it, dissolving the resulting melt, contains 1:; its sodium sulfide, producing green liquor, causticizing it, and introducing the resulting white liquor sodium sulfide-p.}. There is also known a method for the production of cellulose, which includes: presumably: biological treatment of an activated sludge solution with a concentration of 0.5–3.5 g / l from sys-biological treatment of industrial pulp and paper effluent for 5 -10 days to allow excess fluid and alkaline solution at elevated temperature and pressure. The excess liquid after pretreatment is used to prepare an alkaline cooking solution containing 60-80 g / l of active Slag of Biela N acO with a sulfidity of 25-30% 21. There is also known a method for preparing an alkaline cooking solution in dp for producing cellulose-containing lags. zolkokistoy semi-finished product, which concludes in the dissolution of the melt (the mineral part of the spent sulfur liquor; to obtain green liquor, causticize green liquor to obtain strong white sheozok and QcAlKa calcium carbonate - white malam, separating white LrmaMa from 1-; from alkaline residues with hot water with, igrylamide and feeding the resulting white liquor on the solution of the melted white liquor on the melting solution; the obtained strong white lye ocEie. The following cooking defects have the following disadvantages: the white city's clarification rate is not high enough, the organic content is insufficient and low; the open liquor of black liquors formed by using the cooking solutions obtained; the need to use polyacrylamide or other expensive additives for speeding up the processes of sedimentation of white ishama and clarification of the green silk is necessary to use fresh water at the washing stage}; white mud. These factors reduce the efficiency of the process of preparing the cooking solution and impair its quality, the Purpose of the invention and the increase in the efficiency of the process and the improvement of the KaiecxBa cooking solution. This goal is achieved by washing white sludge with biologically purified waste water with an excess sludge concentration of 3-12 g / l. The process of washing the white sludge with a hot aqueous suspension of activated sludge used instead of fresh water is accompanied by a complete alkaline hydrolysis; m of biomass of activated sludge, while the sedimentation rate of the white lulum increases significantly, eliminating the need to introduce polyacrylamide or other additives. similar result. Weak white liquor, enriched with alkaline hydrolysis products of activated sludge, goes further to melt dissolution. The process of clarification of the green liquor formed in this process proceeds much faster. In addition, the size of aggregated calcium carbonate crystals (white sludge) formed during causticization of green liquor enriched with hydrolysis products of activated sludge is larger than during causticization of green liquor, which accelerates the precipitation of white isham in the causticization process and after settling and washing white sludge. Strong white u, epok, obtained by this method, has a higher cooking properties, since besides alkali it contains products of alkaline 7, intracid hydrolysis of activated sludge (amino acid salts, amino alcohols, protein derivatives), which inhibits thermo-oxidative destruction of carbohydrates in the alkaline process boiling. Example 1.1 a liter of white slurry slurry taken from the washing system of the causticization unit of the Solombalskiy PBC (Y 1.40) is settled until the sediment has completely settled. The filtrate is removed, and the precipitate (white sludge) is washed at 70 ° C with an equal volume of biologically purified wastewater with a concentration of activated sludge of 12 g / l. Washing of white sludge at the specified parameters is accompanied by complete alkaline hydrolysis of the activated sludge. After washing the white sludge and settling it with / in the liquor with an alkali content of 15 g / lp, N is fed to the dissolution of the melt. The resulting green cell (total alkali content and 125 g / l in units, sulfide content, alkaline hydrolysis products of activated sludge - 10.5 g / l), clarified by mechanical sedimentation at a temperature of 80 ° C. After clarification, black sludge is obtained, and the resulting green liquor is Tüdwerth caustic ester. by adding calcium oxide, the degree of causticisation is 80%. The resulting reaction mixture is clarified and strong white liquor, having a total alkali content of 125 g / l, active alkali 100 g / l, in units. With a sulfide content of 25%, the degree of causticization 80% of the content of alkaline hydrolysis products of activated sludge 10.5 g / l is used for pulping, and the white sludge is taken with a fresh portion of the aqueous suspension of activated sludge. Example 2. The process of preparation and caustisation of the green silk differs from. described in the example by the fact that for washing the white sludge using biologically purified waste water with a concentration of activated sludge 3 g / l. Example 3. An alkaline aqueous solution is prepared by a known method, while using fresh water for washing the white sludge. Example 4. The preparation and causticization process. The green liquor differs from that described in Example 3 in that fresh water with the addition of polyacrylamide is used for washing the white isham, at a rate of 0.23 kg / ton pulp. Example 5. For the preparation of the cooking liquor, the spent liquor obtained from sodium cooking is used. The process and parameters for the preparation of the cooking solution are similar to those described in Example 1. As a result, a cooking solution of the following composition was obtained: the total alkali content was 23.1 g / l in units. N and Oh, the content of active alkali 23.1 g / l, in units , products of alkaline hydrolysis of activated sludge 10.5 g / l. The main indicators characterizing the process of preparing the cooking solution described in Example 1-5 are given in Table. 1, the data table. 1 show that the use of an aqueous suspension of activated sludge in washing the white sludge leads to an increase in the efficiency of the alkaline cooking solution preparation process. Sulfate pulping of pine pulp raw material containing pulp was carried out with an alkaline cooking solution obtained according to the proposed and known methods. Sulfate cooking mode: temperature rise from 30 to - 90 min, standing at a temperature of 90 min. The hydronic module cooking 1: 4. The consumption of alkaline reagent, the quality indicators of cellulose and spent liquor after cooking are presented in Table. 2. Cooking was carried out basic alkaline obtained in example 5 in the presence of oxygen-containing gas. The main parameters of cooking and quality indicators of the obtained cellulose in comparison with the cooking solution obtained by a known method in the table. 3. The data presented in table. 2 and 3 indicate that the use of an alkaline cooking solution obtained by this method makes it possible to increase the yield of cellulose-containing fibrous semi-finished product and improve its quality indicators. The technical and economic effect of introducing the invention into the industry is that: the yield of pulp increases by 2-3%; the quality indicators of the target product increase) the alkali consumption for cooking is reduced. 10–12% J does not allow the use of expensive additives at the stage of washing the white sludge, increases the calorific value of the spent cheek by increasing the solids content in it by an average of 2%; fresh water consumption is reduced by approx. SOrlOO m / h; the volume of wastewater is reduced. 1 The expected economic effect from the implementation of the proposed invention on the Solombalsky pulp and paper mill will be approximately 1.4 million rubles. in year.

Table

Time of temperature rise to the maximum, per minute

Maximum cooking temperature, ° C

Duration of cooking at minimum TeNmepaType, in min

The initial pressure of oxygen in the autoclave, kgf / cm

The consumption of active alkali.

90

90

160

160

90

90

12

12

Claims (1)

METHOD FOR PREPARING AN ALKALINE COOKING SOLUTION FOR PREPARATION OF A CELLULOSE-CONTAINING FIBROUS SEMI-FINISHED PRODUCT, which consists in dissolving the melt with obtaining green liquor, caustizing the green alkali, clarifying the obtained white liquor, separating the white liquor from it and washing it with white water, washing, washing , characterized in that in order to increase the efficiency of the process and improve the quality of the cooking solution, the white sludge is washed biologically cleaned with wastewater with a concentration of excess activated sludge of 3-12 g / l. >