SU968125A1 - Process for producing pulp - Google Patents

Description

(5) METHOD FOR OBTAINING A PURPOSE

The invention relates to pulp and paper production and can be used in the preparation of pulp. The known method of cooking sulphate pulp in the presence of anthraquinone and its derivatives, the addition of which in the amount of Q ,, to the cooking liquor stabilizes the carbohydrate part of the wood and leads to an increase in the yield of fibrous semi-finished product 1. The disadvantage of this method is that anthraquinone and its derivatives introduced into the cooking liquor, cannot be regenerated and are discharged together with black liquor during the process of regeneration of chemicals (sodium sulphide and sodium hydroxide). The closest to the invention in its technical essence and the achieved effect is a method for producing cellulose, including pretreatment of chips with anthraquinone or its derivatives and an alkaline reagent, separation of the spent solution and subsequent sulphate cooking. According to this method, after the run, the waste solution is separated from the chips, the missing fresh chemicals are introduced into it and reused in the process. The known method partially solves the problem of the regeneration of anthraquinone 2.. However, the known method is not sufficiently high selectivity in the process of delignification. The purpose of the invention is to increase the selectivity of the delignification process. The goal is achieved in that according to the method for producing cellulose, which includes pretreatment of chips with anthraquinone or its derivatives and alkaline reagent, separation of the spent solution and subsequent sulphate cooking, an aqueous solution of sodium hydrosulfide in an amount of 1-5 is used as an alkaline reagent for pretreatment of chips. % by weight and salt dry chips. At the same time, pretreatment of lignocellulosic material is carried out at 120-140 ° C. The increased selectivity of the delignification process is due to the fact that hydrosulfide, being a selective reagent in reactions with lignin, in the presence of anthraquinone reacts more easily with wood substances, without causing an alkaline destruction of carbohydrates from the Henna impregnation stage). The selected pre-impregnation temperature range (120-140 ° C using hydrosulfide does not decrease the process speed. Applying a temperature lower decreases the delignification rate at the cooking stage, while at a temperature above C, there is no significant advantage in either increasing the yield of the semi-finished product or to increase the delignification rate at the cooking stage. Example 1. Preliminary processing of chips (aspen wood) is carried out with a solution of hydrosulfide in the amount of 2% of absolutely dry wood in and anthra quinone; Then the impregnating solution is separated from the wood and the cooking is continued in the presence of white liquor. The treatment conditions are given in Table 1.m-, Table 1

less active alkali consumption than the known one, the lignin content is 1 lower with the same cellulose yield, which indicates an increased selectivity of the delignification process. After separation of the spent solution, the cooking is carried out in an ст cup-type autoclave, placed in an oil bath. Mechanical mixing. After cooking, the wood residue is pulverized, dried and the fiber yield and degree of delignification determined. Cooking conditions, chemical consumption and cuts are given in table. 2 .. Table2 White liquor consumption, units, percentage of absolutely dry wood. Total active alkali consumption, units of MalO. percent of absolute., dry wood Hydro module Increase in temperature from 90 to min. Cooking time at maximum temperature, min. Fiber yield, percentage of absolutely dry wood Delignification degree, number

5968125

EXAMPLE 2 Consumption of caustic soda, anthraquinone and sodium hydrosulfide, as well as the processing conditions are given in table. 3Table3 Consumption of chemicals, units, percent. from absolutely | dry wood: caustic soda hydrosulphide sodium anthraquinone Hydromodule Temperature rise from 20 to, min Sto 1 at, min Cooking 1. Measure the conditions and the result table. k. I

The cost of cooking white liquor, units act., The percentage of absolutely dry wood

SulfiHe,

Total consumption of active alkali, units, percentage of absolutely dry wood

Hydromodule

Temperature rise from 90 to 160 ° С, min

Continued table.

40

Claims (2)

1: 5 55 Cooking time at maximum temperature, min. Fiber yield, percentage of absolutely dry wood63, 6 Delignification degree, Kapp number 38.3 Lignin content,% As can be seen from the table. k, with the same degree of delignification of cellulose and the same lignin content, the fiber yield is 1.5% higher by the proposed method than the known one. The total consumption of chemicals in the form of active alkali for cooking by the proposed method is 2 I below. PRI me R 3. Preliminary processing of aspen wood chips with a solution of caustic soda and sodium hydrosulfide is carried out in the presence of sodium anthraquinone sulfonic acid (an anthraquinone derivative). Impregnation conditions are given in table. 5. Tablets 5. 7 96812 The impregnating solution is separated, the chips are filled with white cooking liquor and the pulp is boiled, as described in Example 1. The conditions of the cooking, the consumption of chemicals and the results obtained are listed in Table. 6. g and c. 6. Total consumption of active alkali, units of Na, jp, percentage of absolutely dry wood 1b, 5 21.5 Hydro module 1: 5 -5 Lifting temperature-. perature from 90 to, min 60 .. 60 Cooking time, min 60 60 Fiber yield, percentage of absolutely dry wood bb 52.1 Delignification degree, Kappa number 2.1.4 18.7 Lignin content,% 2.2 2.0 5 to 15 20 25 30 35 As can be seen from the table. 6, the cellulose obtained by the proposed method with an equal degree of delignification has a fiber yield 4.5 times higher. than by the famous. The invention improves the selectivity of the delignification process and the yield of pulp. This reduces the consumption of alkali reagent, and instead of a hydrosulfide solution, you can use waste petrochemical production, containing hydrosulfide. Claim 1. Method for producing cellulose, including pretreatment of chips with anthraquinone or its derivatives and alkaline reagent, separation of the spent solution and subsequent sulphate cooking, are distinguished by the fact that, in order to increase the selectivity of the delignification process, as an alkaline reagent in the pretreatment of chips use an aqueous solution of sodium hydrosulfide in the amount of 1-5 by weight of absolutely dry wood chips. 2. The method according to claim 1. that is, so that the preliminary processing of chips is carried out at 120-140 C. Sources of information taken into account during the examination 1.Patent GDR fP, cl. 55 1/10, 1973. 2. Canadian patent number 986662, cl. 9-22, 1976 (prototype).