SU1595977A1 - Method of producing sulfate pulp - Google Patents

Abstract

The invention relates to a technology for the production of sulphate pulp for paper and cardboard, as well as chemical processing and improves the quality of pulp while increasing the efficiency of the use of wood raw material. Larch wood chips are subjected to water treatment at a temperature of 100-120 ° C, the resulting spent solution is removed, subjected to ultrafiltration treatment at a temperature of 80-90 ° C with the release of a concentrate containing arabinogalactan and filtrate containing flavonoids. The filtrate is returned to the stage of water treatment, and the pretreated chips are subjected to sulphate cooking. Before returning to the stage of water treatment, the filtrate may be subjected to reverse osmosis treatment with separation of a part of flavanoids. 3 hp f-ly, 3 tab.

Description

The invention relates to the pulp and paper industry and can be used in the production of pulp from larch wood for the manufacture of paper and cardboard, as well as cellulose for chemical processing.

The aim of the invention is to improve the quality of pulp while increasing the efficiency of using wood raw material.

According to the method, larch wood chips are subjected to water treatment at 100-120 ° C, the first spent solution (extract) is removed, and sulphate cooking of the pretreated chips is carried out. After removal of the spent solution, it is subjected to

ultrafiltration treatment with isolation of a concentrate containing arabinogalactin (AH). and filtrate containing flavanoids. which return to the stage of water treatment of wood chips. Ultrafiltration treatment is carried out at 80-90 ° C. The concentrate is directed to drying to obtain a commercial product, arabinogalactan.

According to the proposed method, it is preferable to produce pulp for papers, since the pulp obtained has improved strength properties, the yield of pulp increases. This is due to the presence in the recycled filtrate of low-molecular-weight flavonoid compounds that contribute to the destruction of lignell X (

Xi

on in the cell wall of the fiber and, thereby, intensifying the cooking process and increasing its selectivity.

In the case of increased demands on the purity of the pulp, i.e. upon receipt of cellulose for chemical processing, the filtrate is subjected to additional treatment by reverse osmosis with i release of a part of flavonoids before returning to the stage processing. PRI me R 1. Getting cellulose for

 paper.

Water is poured into a cooking pot with larch wood chips and chips are processed at pressures up to 10 atm and at 100 ° C. Processing time 15 min. Hydromodule 6: 1. After water treatment, a spent extract solution is obtained containing water-soluble

substances.

In tab. 1 shows the composition of the extract. The spent solution is sent to a tubular type ultrafiltration plant with six 5TY-05/2-PCA-1 blocks. Working pressure at ultrafiltration is 02-10 MPa. The processing temperature is maintained within the range of 80-90 ° C. After ultrafiltration treatment, a concentrate is obtained with a solids content of 100–300 g / l and a filtrate with a solids content of 1.0–4.0 g / l. The arabio-galactan containing concentrate is sent for drying to form a commercial arabinogalactane. The filtrate is returned to the processing stage. The processed chips are subjected to sulphate cooking.

In tab. 2 shows the conditions for the cooking and quality indicators of cellulose.

From the data table. 2 it follows that the proposed method, in the case of the production of pulp for paper, provides an improvement in the quality of the pulp — the mechanical strength increases by 10-25%. In addition, the proposed method provides an increase in the selectivity of the cooking process, reducing the amount of lack of penetration by 2.5%. an increase in yield by 2%, residual lignin by 1.5% while reducing the consumption of chemicals by 10%.

In tab. 3 shows the quality indicators of pulp.

Example 2 Cellulose is obtained for chemical processing.

Water treatment of larch chips is carried out under the conditions indicated in Table. 3. After this, the spent solution is displaced from the boiler with the filtrate from the ultrafiltration treatment stage and 90% of the spent solution is fed to

five

ten

15

in and a

an ultrafiltration plant to produce a concentrate that is used to produce marketable arabinogalactan and a filtrate that is subjected to reverse osmosis treatment.

A reverse osmosis installation is used for the treatment. The treatment pressure is 2.0-3.0 MPa, the temperature is 20-70 ° C. The resulting concentrate 0 is dried to produce marketable flavanoids, and the filtrate is sent to the water chip processing stage.

Larch wood chips after water treatment are subjected to preliminary hydrolysis. Hydrolysis conditions: temperature 170 ° C; pressure 0.7-0.8 MPa, the time of prehydrolysis 70 min; hydronic module 6: 1. Then, sulphate cooking of prehydrolyzed larch chips is carried out according to the regime specified in Table 3.

In the prototype method, the spent solution from the water treatment of larch chips is returned to the preliminary water hydrolysis stage, and then 25 sulphate cooking is carried out according to the conditions specified in

table 3

Froze Water treatment of larch chips is carried out under the conditions indicated in Table. 3. After this 50% solution from 30. The aqueous treatment is subjected to ultrafiltration treatment as in Example 1. Next, the operations are carried out in a sequence similar to Example 2.

From the analysis of data table. 3, it follows that 35 in the case of obtaining cellulose for chemical processing, the proposed method provides an improvement in the purity and quality characteristics of cellulose compared with the prototype method. At the same time, 40% mass fraction of alpha-cellulose-94 is reached, 5%.

The proposed method provides the ability to comprehensively use larch wood with the release of 45 valuable products - arabinogalactan and flavanoids.

Claims (4)

Claim 1. A method for producing sulphate pulp, which includes water treatment of larch wood chips 50 at elevated temperature, removal of the resulting waste solution, returning the waste solution to the water treatment stage and sulphate cooking of pre-55 processed chips, characterized in that pulp while increasing the efficiency of use of wood raw material, after removing the spent solution, it is subjected to ultrafiltration treatment Ke with the release of a concentrate containing arabinogalaktan, and a filtrate containing flavanoids, and the specified filtrate is returned to the water treatment stage. 2. The method according to claim 1, about t l and h ayusch and with the fact that before returning to the stage of water treatment, the filtrate is subjected to processing reverse osmosis with the release of part of flavanoids. 3. Method according to claim 1, characterized in that the water treatment of the wood chips is carried out at 100-120 ° C. 4. Method according to claim 1, characterized in that the ultrafiltration treatment is carried out at 80-90 ° C. Table 1 Indicators Cooking method prototype Consumption of active alkali in units NaOH,% of the mass of absolutely dry wood liquor,% Duration of heating up to 170 ° C, min. Cooking duration at 170 ° С, min. Cooking hydromodule Output by weight of absolutely dry wood,%: Cellulose Not penetrated General The lignin content in the pulp,% The degree of delignification, units Kappa Indicators of mechanical strength when grinding 60 ° SR and the weight of the castings 100 g / m of the obtained cellulose: breaking length, m kink resistance, number of bits kinks resistance to bursting, kPa resistance to tearing, pl Table 2 Cooking on the proposed method 20.0 30.3 90 60 4: 1 34.3 2.2 36.5 4.1 27 9100 5450 550 210 Table3