RU2318940C1 - Method for producing of cellulose - Google Patents

Abstract

FIELD: pulp-and-paper industry, in particular, production of sulfite cellulose.

SUBSTANCE: method involves mixing fir tree and hardwood chip; performing sulfite pulping of mixture and washing resulted pulp, with young thin birch wood being used as hardwood chip produced after wood care cuttings in an amount making 10-60% by total amount of raw wood material.

EFFECT: simplified method for producing of cellulose, wider range of raw material base and reduced cellulose production costs.

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Description

The invention relates to the pulp and paper industry (PPI) and can be used at the enterprises of the pulp and paper industry in the production of sulphite pulp.

A known method of producing unbleached pulp by cooking a mixture of wood chips from larch and spruce wood in equal volumes at elevated temperature and pressure with sulfite cooking solution (see RU No.2010068, class D21C 3/06, op. 30.03.94).

The disadvantage of this method is the production of cellulose with high Kappa numbers (31.8-57.0), insufficiently high whiteness (61.0-62.0%), which will subsequently require a high consumption of chemicals for bleaching pulp.

Closest to the proposed method is a method of producing cellulose by mixing spruce and deciduous wood chips, cooking the mixture and washing the mass, before mixing the deciduous and wood chips are treated with a 0.5-3.0% solution of the delignification inhibitor selected from the group consisting of hydroxide sodium, calcium hydroxide and urea at a hydraulic unit of 4-6, a temperature of 50-80 ° C for 1-3 hours (see SU No. 990916, class D21C 3/04, 1/06, op. 23.01.83).

The disadvantages of this method are the complexity and duration of the process, since before mixing the chips, it is necessary to pre-treat the hardwood chips with chemical reagents for 1-3 hours

Pulp and paper industry enterprises experience certain difficulties in raw materials due to increased production of fibrous semi-finished products, which is associated with depletion of forest resources, especially in the European part of the country. One of the reserves of raw materials for pulp and paper industry can be young fine wood obtained during thinning operations (during clarification, cleaning, thinning). The resources of this wood are so great that they can largely cover the growing needs of the industry for raw materials. When carrying out thinning, they receive young fine-sized hardwood, mainly birch.

The objective of the invention is to provide a method to simplify the process of producing cellulose, reduce the cost of feedstock, expand the raw material base of pulp and paper industry and improve the environment.

The technical result achieved in solving this problem is to simultaneously reduce the Kappa number and increase the brightness of pulp, expand the raw material base and reduce the cost of raw materials for producing technical pulp.

This technical result is achieved by the fact that in the method of producing cellulose, comprising mixing spruce and deciduous wood chips, sulphite cooking of the mixture and washing the mass, young fine-sized birch wood obtained in the course of logging in the amount of 10 is used as deciduous wood chips -60% of the total amount of wood raw materials.

Carbon spruce is a traditional raw material for sulphite pulp. Typically, deciduous wood, including ripe birch, during sulphite cooking is delignified more easily than spruce wood, which leads to digestion of hardwood pulp during the joint cooking of coniferous and deciduous wood. The wood of young fine-sized birch delignifies more slowly than ripe, therefore it can be used as an additive for sulphite cooking of pulp spruce. At the same time, good penetration uniformity is achieved. In addition, young fine-sized birch wood contains a lower mass fraction of resins and fats than ripe birch wood.

Young, fine wood can only be processed using alkaline cooking methods.

Signs that distinguish from the prototype, the use as deciduous wood chips of young fine wood birch in the amount of 10-60% of the total amount of wood raw materials.

The proposed method for producing cellulose is as follows.

Chips from a mixture of ripe spruce wood and young fine-sized birch wood are loaded into an autoclave. In order to approach production conditions, the sodium base cooking solution is preheated to 70-75 ° C, poured into an autoclave and pulp is cooked. After cooking, the resulting cellulose is washed with cold water.

Examples of specific performance.

Example 1. Chips from ripe spruce wood were loaded into an autoclave and poured with a cooking solution on a sodium base, which was previously heated to a temperature of 70-75 ° C. Next, pulping was carried out according to the following temperature conditions:

- rise in temperature to 105 ° C - 60 min,

- parking at a temperature of 105 ° C - 100 min,

- temperature rise to 138-140 ° C - 90 min,

- cooking at a final temperature of 110 min.

The hydraulic unit during cooking was 5: 1.

After cooking, the pulp was washed with cold water.

Example 2. Chips from ripe spruce wood with the addition of chips from young fine-sized birch wood in an amount of 10% were loaded into an autoclave and poured with a cooking solution on a sodium base, which was previously heated to a temperature of 70-75 ° C. Next, cellulose was cooked according to the above temperature regime.

The hydraulic unit during cooking was 5: 1.

After cooking, the pulp was washed with cold water.

Examples 3-7. Chips from ripe spruce wood with the addition of chips from young fine-sized birch wood in an amount of 20-60% were loaded into an autoclave and poured with a cooking solution on a sodium base, which was previously heated to a temperature of 70-75 ° C. Next, cellulose was cooked according to the above temperature regime.

The hydraulic unit during cooking was 5: 1.

After cooking, the pulp was washed with cold water.

Example 8. Chips from young fine-sized birch wood were loaded into an autoclave and poured with a cooking solution on a sodium base, which was previously heated to a temperature of 70-75 ° C. Next, cellulose was cooked according to the above temperature regime.

The hydraulic unit during cooking was 5: 1.

After cooking, the pulp was washed with cold water.

The results of sulfite boiling from the chips of ripe spruce wood, young fine-grained birch wood and a mixture of ripe spruce wood and young fine-grained birch wood in various ratios are presented in the table.

As can be seen from the table, the addition of fine birch in the amount of 10-60% to ripe spruce wood does not practically affect the pulp yield, and the mechanical strength indicators remain at a fairly high level.

The proposed method of producing cellulose in comparison with the prototype allows to simplify the process technology by eliminating the stage of impregnation of wood chips with chemical reagents; reduce the cost of raw materials through the use of young fine-sized birch wood obtained during thinning; expand the raw material base of pulp and paper industry enterprises.

Table
The effect of the addition of young fine birch on the results of sulphite cooking of ripe spruce wood Example No. The composition of the feedstock,% Cellulose yield,% of the original wood White,% Pulp performance Ripe spruce Young birch The degree of delignification (Kappa number) Breaking length, m Resistance Punching, kPa Kink, ch.p. one one hundred - 50,2 65.0 twenty 8550 460 2100 2 90 10 50.3 65.0 twenty 8550 460 2090 3 80 twenty 50.3 65.0 twenty 8550 460 2080 four 70 thirty 50.3 64.7 21 8540 460 2080 5 60 40 50.7 64.7 21 8520 450 1920 6 fifty fifty 51.1 64.3 22 8510 450 1800 7 40 60 51.5 64.3 22 8500 440 1690 8 - one hundred 52,5 64.0 23 8460 420 1250

Claims (1)

A method of producing cellulose by mixing spruce and deciduous wood chips, sulphite cooking of the mixture and washing the mass, characterized in that as the deciduous wood chips use young fine-sized birch wood obtained by cutting wood care, in the amount of 10-60% of the total the amount of wood raw materials.