SU787517A1 - Method of obtaining fibrous mass - Google Patents

Description

one

The invention relates to pulp and paper production, to methods for producing fibrous masses using pressure relief, intended for the production of paper, frame-5 tones and fibreboard.

A known method of obtaining pulp by impregnating crushed chips with liquid ammonia in two stages, of which in the first stage "O impregnation is carried out at room temperature, the second stage is heated to 94-150 ° C with an increase in pressure to 70 MPa. Instant pressure release from the closed area to a zone with 15 much lower pressure leads to the splitting of the impregnated chips into fibers and puchvyvolokon, which are washed, ground, bleached and used for the intended purpose l, 20

The disadvantage of this method is the use of liquefied ammonia, which is associated with the high consumption of the latter and the need to regenerate it.25 Processing chips in two steps makes it difficult to intensify the process. In addition, the liquefied ammonia used does not effectively split the chips into fibers.30

A known method for producing pulp by impregnating wood chips, which are conducted in one step, with a mixture of aqueous solutions of ammonia and sodium hypochlorite at 150-210 seconds.

A mixture of ammonia and hypochlorite at a certain ratio of them has reducing properties. As a result of a series of reactions, hydrazine is formed, contributing to an increase in the yield of pulp and providing satisfactory re-. splitting of chips into fibers.

The disadvantage of this method is the need for a large hydromodule impregnation, since the amount of α-hydrazine reducing agent formed is directly dependent on the amount of sodium hypochlorite and ammonia. In addition, in a known method, chlorine-containing reagent is used, which is associated with the need for operations and equipment for its preparation, which is formed during the interaction of ammonia and hypochlorite, hydrazine is a toxic reagent.

The disadvantage of this method is also the low quality of the fibrous mass.

The purpose of the invention is to increase the physico-mechanical properties of the pulp.

The goal is achieved by the fact that wood chips are impregnated with an aqueous solution of ammonia with the presence of hydrosulfite. Sodium and chelate compounds, which are Trilon B or alkaline mtal phosphate. The ratios of ammonia and sodium hydrosulfite are maintained from 8: 1 to 2: 1. The chelate compound is introduced in the amount of 0.01-0.5%, and sodium hydrosulfite in the amount of 1-5% by weight of absolutely dry wood.

The mass with a concentration of 20-30% after depressurization is subjected to grinding in the presence of hydrogen peroxide, alkali and sodium silicate, followed by an acidic mass to a pH of 5-7. Then the mass is grinded at a concentration of 6-20% to the degree of grinding, castings are made and physical and physical indicators are determined.

The method is carried out as follows.

Wood chips, for example, birch, are loaded into the chamber heated to 150-155 ° C, an aqueous 25% solution of aNBuiHaKa, a water ratio from 1: 2 to 1: 3, and also sodium hydrosulfite in the amount of 1.0 are fed through a special charging device. -5.0% and Trilon B in an amount of 0.01-0.5% of absolutely dry wood. The chamber is heated for 56 minutes to 170-175 ° C and a pressure of 20–22 MPa. When the above parameters are reached, the sealing device opens and plasticized chips are thrown through a nozzle into a zone with significantly less pressure. The chips are then divided into fibers and fiber bundles.

Then, a coarse decompression mass with a concentration of 20-30% in the presence of hydrogen peroxide, alkali and sodium silicate is passed through a refiner in order to separate the mass into fibers.

After separation, the mass is acidified (with acetic, sulfurous, nitric or other acids) to a pH of 5-7 and the grinding of a mass of 6–30% to a grinding degree is carried out.

Example 1. In laboratory conditions, 112 g of air-dry birch chips (100 g of absolutely dry wood) are standard sizes; Put it in a pre-heated ISOc chamber. The chamber is closed and 200 ml of a 25% aqueous solution of ammonia, 1.0 g of sodium hydrosulfite and 0.01 g of trilon B are fed through the metering device. The chamber is heated for 5 minutes before and at a pressure of 20 MPa. Thereafter, instantaneous depressurization and chips are made through

A nozzle device in the form of bundles and individual fibers is ejected from the chamber. A mass concentration of 20% is separated on a Spout Waldron disk refiner in the presence of 2 g of hydrogen peroxide, 2 g of soda and 0.02 g of 5 nt silicate.

After separation, the mass is acidified with sulfuric anhydride solution until. and lead grinding at a mass concentration of 6% to the degree of grinding. At 0 sheet-cutting apparatus make samples of paper weighing 100 g / m. The indicators characterizing the fibrous mass are shown in the table.

Example 2. The conditions for obtaining 5 pulp are the same as in Mejpe 1. The difference is that 250 ml of an aqueous ammonia solution, 5 g of sodium hydrosulfite and 0.2 g of trisodium phosphate are supplied to the dosing device. 0 A mass concentration of 25% is separated on a disk refiner in the presence of 3 g of hydrogen peroxide, 1 g of soda and 0.02 g of sodium silicate. After separation, the mass is acidified with a solution of acetic acid before and grind at a mass concentration of 20% to the degree of grinding. Paper samples weighing 100 g / m are made on a sheet-cutting apparatus. The indicators characterizing the fibrous mass are shown in the table.

Example 3. The conditions for obtaining a pulp are the same as in Example 1. The difference is that 300 ml of an aqueous ammonia solution, 2.5 g of sodium hydrosulfite and 0.5 g of potassium pyrophosphate are supplied to the dosing device. Mass concentration of 30% is separated on a disk refiner in the presence of 2.5 g

0 hydrogen peroxide, 1.5 g soda and

0.02 g of sodium silicate. After separation, the mass is acidified with a solution of acetic acid to pH 6 and grind at a concentration of 15% to the degree

 grinding Paper samples weighing 100 g / m are made on a sheet taking apparatus. The indicators characterizing the fibrous mass are shown in the table.

Example 4. Parsley received fiber pulp in the same way as described in the known method.

A mass concentration of 20% is separated on a disk refiner in the presence of 5 2 g of hydrogen peroxide, 2 g of soda and 0.02 g of sodium silicate. After separation, the mass is acidified with a solution of sulfur dioxide and grind at a mass concentration of 15% to Q degree of grinding. The indicators characterizing the fibrous mass are shown in the table.

Breaking length, m

Kink, the number of double kinks

Burst resistance, kgf / cm

5600 5800

4900 65. 85

22 2.1 2.6 3.0

Claims (2)

From the data presented in the table, it can be seen that the use of an aqueous solution of ammonia in combination with sodium hydrosulfite and a chelate type compound for pre-decompression treatment of birch chips increases the whiteness of the target product while at the same time achieving high physical and physical properties. Increasing the whiteness of the pulp dramatically reduces the consumption of chemicals required for bleaching and, in turn, reduces water consumption. The fibrous mass obtained by the proposed method can be used in the composition of paper, for example, newsprint, where it will replace softwood sulphite pulp. When replacing sulphite pulp in the composition of paper 10, the economic effect is 2 rubles. per ton of paper. The method is simple, economically beneficial, contributes to environmental protection, since it does not contain chlorine-containing reagents. Claims of the invention 1. A method for obtaining a pulp by impregnating wood chips. an aqueous solution of ammonia in the presence of an additive at elevated temperature and pressure, followed by pressure relief, characterized in that, in order to increase the physical and mechanical mass parameters, a mixture of sodium hydrosulfite and chelate is used as an additive, while sodium hydrosulfite is introduced in the amount of 1-5 %, and chelate compound in the amount of 1.01-0.5% by weight of absolutely dry wood. 2. The method according to claim 1, is also distinguished by the fact that ethylenediaminetetraacetic acid or alkaline phosphate is used as the chelate compound. Sources of information accepted in review during examination 1. Patent of 01 January 343618, cl. About 21 in 1/36, 1973. 2. Copyright certificate 478083, cl. O 21 1/00, 1975 (prototype)