SU821613A1 - Method of obtaining fibrous cellulose-containing semifinished product - Google Patents

Description

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The invention relates to a method for producing a semi-finished fibrous material and can be used in the pulp and paper industry in the manufacture of hardwood semi-finished products for paper to cardboard by sulphate cooking.

The known method is the preparation of fibrous cellulose containing material. semi-finished product, which consists in the fact that sulphate cooking of birch wood is carried out in 2 steps. During the cooking process, the alkaline solution is removed and replaced with an alkaline solution taken from another boiler, in which the cooking has started later 1.

The closest to the proposed technical essence and the achieved result is the method consisting in sulphate cooking of the initial cellulose-containing raw material at elevated temperature and pressure and separating the waste black liquor from the cellulose containing semi-finished product 2).

However, in the processing of hardwood, especially birch, resinous difficulties are observed even in the sulphate method of cooking, which is associated with the chemical composition of resinous substances of hardwood. With an increase in the yield of cellulose-containing semi-finished product, the content of resinous substances and lack of penetration increases in it. The purpose of the invention is to reduce the content of resinous substances and lack of penetration in the target product.

The goal is achieved by the fact that after taking strong black liquor, the pulp mass is treated with a solution of NaOH at 60-95 ° C and its consumption is 0.3-1.5% of the mass of absolutely dry cellulose for 5-30 minutes

The method is carried out as follows.

Hardwood chips are subjected to sulphate cooking at 160-190 ° C, 6-12 atm, with an active alkali consumption of 8-20% in units of NaOH. The duration of cooking at the final telesheratura is 5-120 minutes, depending on the conditions of cooking, the size of the chips, and the desired yield of the cellulose-containing semi-finished product.

After the end of cooking, strong black liquor is taken, the temperature of the mass is reduced to 60-90 ° C, then NaOH in an amount of 0.3-1.5% by weight of the absolutely dry cellulose-containing semi-finished product is contained in the amount of 5- 30 min.

Example 1. Sulfate pulping of birch wood chips is carried out at 160 and 180 ° C. The content of resinous substances (resins and fats in wood is determined by extraction with dichloroethane. In birch wood used for the tests, the content of resins and fats is 1.8%.

As a result of cooking, cellulose contents are obtained from a semi-finished high yield.

Data on the results of cooking are presented in table 1.

Experiments 1-3 are carried out according to the mode of the known method, i.e. by the sulphate method of cooking, followed by semi-milling grinding of the obtained semi-finished product on the Spout Waldrov refiner. The yield of semi-finished product is 77.2-63.6% by weight of absolutely dry wood. The content of resinous substances in the semi-finished product is 1.81-2.37%, and in terms of the initial wood 0.58-1.50%.

According to the proposed method, experiments 4 and 5 are performed. Birch wood is boiled by the sulphate method according to the mode of experiments 1 and 2, after which strong black liquor is collected, 0.3% of the weight of absolutely dry semi-finished product is added to the pulp. After the treatment, the obtained semi-finished product imposes hot half-mass times216134

the mole The content of resinous substances in the semi-finished product obtained by the proposed method, in the experience of 4-0,73% against 1.8% by a known method (experiment 1), and experiment No. 5 1,10%

5 vs. 2.37% (experiment 2).

In tab. 1 shows the results of pulping pulp-containing semi-finished product of high output from birch, in table. 2 - results of pulping normal output.

JO PRI mme R 2. Birch wood is boiled by the sulphate method at 176 ° C with an active alkali consumption of 17.18 and 20% in NaOH to the weight of absolutely dry wood.

Additional processing of cellulose-containing 5 semi-finished product is carried out after selection of strong black liquor, NaOH is added 0.8 and 1.5% by weight of absolutely dry semi-finished product. The treatment leads to a significant decrease in the content of resinous substances in comparison with the known method, as well as to a decrease in the amount of lack of penetration in the cellulose-containing semi-finished product from 25 to 0.2%, i.e. semi-finished product (cellulose), obtained by the proposed method, practically does not contain a lack of penetration.

The addition of NaOH does not increase the content of residual alkali in the pulp.

Claims (2)

The proposed method for producing cellulose-containing fibrous semi-finished product is expedient to use in the processing of hardwood. 9. The invention The method of obtaining a fibrous cellulose-containing semi-finished product by sulphate pulping of the original cellulose-containing ryr at IBO-180 ° C, 6-12 atm, the consumption of active alkali 8-20% NaOH and selection of strong black liquor after cooking, characterized in that, in order to reduce the content of resinous substances and lack of penetration in the target product, after selecting a strong black liquor 3, the pulp is treated with a solution of NaOH at 60-95 ° C and its consumption is 0.3-1.5% by weight of absolutely dry cellulose for 5-30 minutes . Sources of information taken into account in the examination 1. Swedish Patent N 317250, cl. D 21 3/02, onlib. 1969. 2.Nepeyin Yu. N. Pulp technology, vol. II, Goslesbumizdat, 1963 (prototype).