RU2368715C1 - Cellulose washing method - Google Patents

Abstract

FIELD: textiles, paper.

SUBSTANCE: method refers to cellulose washing method and can be used in pulp and paper industry to obtain sulfite cellulose when producing paper and cardboard and chemical processing. Cellulose is rinsed with cold water in the presence of organic additive agent SAA of weakly anionic type - compound UMS-1. The present additive is water-based mixture of biodegradable ethoxylated fatty alcohols and non-chlorinated solvents. Additive consumption makes 0.005-0.02% of completely dry pulp weight.

EFFECT: enhancement of cellulose washing efficiency and pulldown of common and hazardous resin content in cellulose.

3 tbl, 15 ex

Description

The invention relates to a technology for the production of pulp and can be used at the enterprises of the pulp and paper industry, producing sulfite pulp for the manufacture of paper, cardboard, as well as for chemical processing.

A known method of producing fibrous semi-finished product, according to which, after pulping and selecting strong liquor, the pulp is subjected to treatment with a NaOH solution at 60-95 ° C and its consumption of 0.3-1.5% by weight of absolutely dry cellulose for 5-30 minutes ( SU No. 821613, class D 21C 3/02; 9/00; publ. 15.04.81).

The disadvantages of this method are the high consumption of NaOH, high processing temperature, the difficulty and duration of washing NaOH with cold water from cellulose fiber.

The closest method of the same purpose to the claimed invention according to the totality of features is a method of washing the pulp after cooking, including treating the pulp with water or a sodium hydroxide solution in the presence of an additive - the product of neutralizing soluble pyrogenic wood resin with aqueous solutions of sodium hydroxide and calcium hydroxide (LCD). Moreover, the specified additive is taken in an amount of 0.5-2.0% by weight of absolutely dry cellulose, and the washing liquid has a temperature of 80-90 ° C (SU No. 1601260, class D21C 9/00; 3/02, publ. 23.10 .90). This method is selected as a prototype.

The disadvantages of the known method adopted for the prototype are the high consumption of additives when washing the pulp after cooking (0.5-2.0% by weight of absolutely dry cellulose); use for washing hot water with a temperature of 80-90 ° C; insufficient effect of desalting when using LHD (4-30%); lack of data to reduce the content of "harmful" resin in cellulose fiber.

In pulp and paper industry there are 2 characteristics of the resin: general and "harmful". The most dangerous is the "harmful" or emulsified resin, the emulsion of which is not stable and can easily be broken with the agglomeration of individual particles into large clots. A characteristic feature of “harmful” resin is the ability to give sticky formations that cause manufacturing difficulties: deposition of resin on equipment (sortings, pipelines, etc.), contamination of paper machines, and this in turn leads to breakage of the paper web, paper scrap (tar spots, holes, etc.) and machine downtime due to blowing or washing of paper nets.

The features of the prototype, which are common with the claimed invention, is the treatment of pulp with water in the presence of an organic additive.

The objective of the invention is to increase the washing efficiency of the pulp and to reduce the content in the pulp of the total and "harmful" resin.

The problem is solved due to the fact that in the known method, which includes, after cooking, the pulp is treated with water in the presence of an organic additive, the pulp is treated with cold water and a weakly anionic type surfactant is used as an organic additive - UMS-1, which is an aqueous mixture of biodegradable ethoxylated fatty alcohols and non-chlorinated solvents, at a flow rate of 0.005-0.02% by weight of absolutely dry cellulose.

Signs that distinguish from the prototype, washing pulp after cooking with cold water; using as an organic additive for washing cellulose surfactants of a weakly anionic type, the preparation - UMS-1 in an amount of 0.005-0.02% by weight of absolutely dry cellulose.

The anti-resinous effect of UMS-1 is ensured by the following: the anti-precipitating components that make up the preparation ensure that the resin is already separated from cellulose fibers in an emulsified state, prevent the formation of sticky resin agglomerates and prevent the resin from precipitating on fiber and equipment. Most emulsified resins leave with wash water.

The proposed method of washing the pulp is carried out in the following sequence.

Wood chips are loaded into an autoclave. The cooking solution on a sodium-magnesium base is preheated to 70-75 ° C, poured into an autoclave and pulp is cooked. At the end of cooking, the cellulose is washed with cold water with the addition of a surfactant as follows: the free liquor is drained from the autoclave, the cellulose with residual liquor is placed in a disintegrator, which contains 1 liter of cold water with a temperature of 10-15 ° C, containing UMS-1 in the amount 0.005-0.03% by weight of absolutely dry cellulose. Cellulose is pulled into fibers in a surfactant solution in a disintegrator, and further washing is carried out with cold cold tap water on laboratory sieves until the foam disappears.

Examples of specific performance.

Example 1

Spruce wood chips were loaded into an autoclave and poured with a cooking solution on a sodium-magnesium 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 115 ° C - 1.5 hours;

- parking at a temperature of 115 ° C - 2.0 hours;

- rise in temperature to 160 ° C - 2.0 hours;

- cooking at a temperature of 160 ° C - 2.0 hours

The hydraulic unit during cooking was 5: 1.

After cooking, the pulp was pulped into fibers in a disintegrator in the presence of cold water with a temperature of 10-15 ° C and then washed with cold water on laboratory sieves.

Examples 2-5.

Spruce wood chips were loaded into an autoclave. The cooking solution on a sodium-magnesium base was preheated to a temperature of 70-75 ° C, poured into an autoclave and pulp was cooked according to the temperature regime described in Example 1. After cooking, the resulting pulp was pulled into fibers in a disintegrator in the presence of cold water, in which dissolved the preparation UMS-1 in an amount of respectively 0.005%; 0.01%; 0.02%; 0.03% by weight of absolutely dry cellulose. Next, the pulp was washed on laboratory sieves with cold water.

Example 6

Cellulose was cooked and washed in the same manner as in Example 1. Aspen wood was used for cooking.

Examples 7-10.

Cooking and washing the pulp was carried out as in examples 2-5. For cooking used aspen wood.

Example 11

Cooking and washing the pulp was carried out in a similar manner as in example 1. For cooking used birch wood.

Examples 12-15.

Cooking and washing the pulp was carried out as in examples 2-5. For cooking used birch wood.

The resulting cellulose samples were determined yield, total and "harmful" resin, the degree of penetration.

The effect of the UMS-1 additive upon washing pulp after cooking on the above indicators is shown in Tables 1-3.

From the data of table 1 it is seen that with an increase in the consumption of surfactants when washing spruce pulp, the total and “harmful” resin content of the pulp samples decreases. However, the most effective reduction in “harmful” resin content is observed at surfactant costs of 0.01-0.02% by weight of absolutely dry cellulose. A further increase in UMS-1 consumption to 0.03% of the mass of absolutely dry cellulose reduces the “harmful” cellulose gum content less significantly.

When washing aspen cellulose (table 2), the most rational consumption of surfactants is the consumption in the amount of 0.01% by weight of absolutely dry cellulose. At the indicated surfactant consumption for washing, the total resin in cellulose is reduced by 40.3% and the "harmful" resin by 39.8%. In this case, an increase in the dosage of surfactants (more than 0.01% by weight of absolutely dry cellulose) in the washing liquid cannot be considered expedient for economic reasons.

When washing birch cellulose (table 3), the addition of UMS-1 in an amount of 0.005% by weight of absolutely dry cellulose made it possible to reduce the total resin content in birch cellulose by 30.9% and a further increase in surfactant consumption to 0.03% by weight of absolutely dry cellulose to reduce the total resin content by only 10.3%. Thus, to effectively reduce the total resin content in birch cellulose, a surfactant consumption of 0.005% by weight of absolutely dry cellulose is sufficient. However, reducing the “harmful” resin content of birch cellulose is much more difficult. To reduce this indicator by 32%, UMS-1 consumption of 0.02% by weight of absolutely dry cellulose is required.

The proposed method of washing pulp allows you to:

- reduce the consumption of additives when washing the pulp after cooking and use cold water for washing;

- reduce the total and "harmful" resinous cellulose.

This indicates increased efficiency and economy of the washing method compared to the prototype.

Table 1
The effect of surfactant consumption during washing on the degumming of cellulose Example No. UMS-1 consumption during washing,% of absolutely dry cellulose The degree of penetration of cellulose, units Cellulose yield,% of the original wood Mass fraction in cellulose of resins and fats,% Cellulose degumming,% Mass fraction of "harmful" resin in cellulose, g / 100g Decrease in “harmful” resin content,% Spruce pulp one - 106 51.0 1.28 - 28.7 - 2 0.005 101 49.6 0.90 29.7 24.5 14.6 3 0.01 103 50.1 0.84 34,4 18,4 35.9 four 0.02 112 52,2 0.78 39.1 15.0 47.7 5 0,03 107 50.9 0.65 49.2 13,4 53.3

table 2
The effect of surfactant consumption during washing on the degumming of cellulose Example No. UMS-1 consumption during washing,% of absolutely dry cellulose The degree of penetration of cellulose, units Cellulose yield,% of source wood Mass fraction in cellulose of resins and fats,% Cellulose demineralization,% Mass fraction of "harmful" resin in cellulose, g / 100g Decrease in “harmful” resin content,% Aspen cellulose 6 - 65 52.6 2.11 - 29.9 - 7 0.005 63 53.0 1.37 35.1 22.7 24.1 8 0.01 61 53.8 1.26 40.3 18.0 39.8 9 0.02 64 54.3 1.19 43.6 15,5 48,2 10 0,03 64 54.6 1.13 46,4 14.8 50.6

Table 3
The effect of surfactant consumption during washing on the degumming of cellulose Example No. UMS-1 consumption during washing,% of absolutely dry cellulose The degree of penetration of cellulose, units Cellulose yield,% of source wood Mass fraction in cellulose of resins and fats,% Cellulose demineralization,% Mass fraction of "harmful" resin in cellulose, g / 100g Decrease in “harmful” resin content,% Birch pulp eleven - 91 53,2 1.78 - 20.9 - 12 0.005 82 51.9 1.23 30.9 17.4 16.7 13 0.01 84 52.0 1.16 34.8 15,2 27.3 fourteen 0.02 87 52,4 1.09 38.6 14.2 32,0 fifteen 0,03 86 52,2 1,04 41.2 12.9 38.3

Claims (1)

A method of washing cellulose, including, after cooking, treating the pulp with water in the presence of an organic additive, characterized in that the pulp is treated with cold water and a weakly anionic type surfactant is used as the organic additive - UMS-1 preparation, which is an aqueous mixture of biodegradable ethoxylated fatty alcohols and non-chlorinated solvents, with its consumption of 0.005-0.02% by weight of absolutely dry cellulose.