RU2287036C1 - Method of preparing cellulose-containing material - Google Patents

Abstract

FIELD: paper-and-pulp industry.

SUBSTANCE: cellulose-containing material preparation method provided by invention can be used in sulfate and natron cellulose production processes. Cellulose-containing stock is subjected to alkaline treatment at heating and pressure in presence of dispersion containing anthraquinone-containing additive particles and black lye. Dispersion is prepared by jointly grinding anthraquinone-containing additive particles in black lye medium at lye-to-additive ratio (0.71-0.91):1 and process is effected until density of dispersion achieves 1.07-1.20.

EFFECT: enhanced pulping efficiency.

1 tbl, 7 ex

Description

The invention relates to chemical technology and can be used in the pulp and paper industry in the production of pulp by the sulfate or soda method.

A known method of producing cellulose-containing material by cooking ligno-carbohydrate material with an alkaline cooking solution under the influence of temperature and pressure in the presence of a suspension of anthraquinone and / or their derivatives in an aqueous alkaline medium (DE 2816473, class D 21 C 5/00, publ. 1979).

The closest analogue is a method of obtaining a cellulose-containing material using a suspension for cooking cellulose containing particles of anthraquinone and black liquor to prevent aggregation and reduce particle deposition, while the particles of anthraquinone are in suspension with the following particle size and quantitative composition, wt.%: Particles with size 0.04-0.06 mm - 12-13; 0.06-0.10 mm - 38-39; 0.1-0.2 mm - the rest, and the ratio of the components in the suspension anthraquinone: black liquor is respectively 17-51: 49-83 wt.% (SU 1327943, CL 01 F 3/12, publ. 1987).

The disadvantages of these methods are the low stability of the suspension at rest, the high dependence of the stability of the suspension on the particle size distribution of anthraquinone particles, constant stirring is required to maintain the suspension in suspension. This is due to the fact that when mixing anthraquinone in a mixer, an effective grinding of anthraquinone particles is not achieved with the formation of a fracture resistant system.

The technical result of the invention is to increase the efficiency of the pulping process.

This technical result is achieved by the fact that in the method of producing a cellulose-containing material by alkaline treatment of cellulose-containing raw materials under the influence of temperature and pressure in the presence of a dispersion containing particles of anthraquinone-containing additives and black liquor, according to the invention, the dispersion is prepared by co-grinding the particles of anthraquinone-containing additives in black liquor when they are the ratio, respectively, 0.71-0.9: 1 to achieve a dispersion density of 1.07-1.20. In this case, a uniform distribution of particles of anthraquinone-containing additive (AHD) is achieved in the cooking volume and at the surface of the ligno-carbohydrate material, which improves the reactivity of the system (ligno-carbohydrate material - AHD - the cooking solution) and leads to an increase in the efficiency of the cooking process taking place at the phase boundary in order to obtaining pulp of uniform penetration, reducing energy costs for preparing, mixing and transporting the suspension, eliminating clogging of pipes, pumps and transport equipment udovaniya. When preparing a suspension, wet grinding is performed with a change in the particle size distribution of AHD instead of mixing, and when wet grinding in black liquor, the AHD is ground by a cutting-abrasive method to form a final suspension with a density of 1.07-1.20 and surface modification of the particles of AHD by surface-active substances, contained in black liquor, with the formation of a dispersion-resistant dispersion system.

Black liquor, of a certain density, contains surfactants and is a by-product of sulfate cooking [Nepenin Yu.N. Cellulose technology, vol. 2, M .: Forest industry, 1990]. Black liquor is a mixture of organic (2/3) and inorganic (1/3) substances. Organic substances consist of lignin degradation products, carbohydrate breakdown products, sodium salts of tar and fatty acids, sulfate soap. Inorganic substances consist of sodium hydroxide, sodium salts (carbonates, sulfates, thiosulfates).

As AHD, products with anthraquinone content up to 70% with an initial particle size of 10-2.5 · 10 ⁴ m (TU-6-36-1095-89) are used.

The invention is illustrated by the following examples. Sulphate cooking of pine chips was carried out in an autoclave under the following conditions:

consumption of active alkali to absolutely dry wood 12-22% (in units of Ma ₂ O), sulfide content 15-30, hydromodule 4-4.5, maximum cooking temperature 170-175 ° C, duration to reach maximum temperature 90-210 min, duration cooking 180-240 minutes AHD is used in the form of a dispersion obtained by grinding AHD in a mechanical mill at a rotation speed of 120-180 rpm. As the dispersion medium, black liquor with a density of 1.083-1.083-1.197 (at a temperature of 20 ° C) is used. The grinding time is 10-50 minutes. The temperature in the grinding zone is 60-80 ° C.

The yield of technical pulp and the determination of the lack of penetration are calculated as a percentage of the load of absolutely dry wood. The degree of delignification is determined by the standard method of ST SEV 6600-89, ISO 302-81. Breaking length according to GOST 13525.1-79. Tear resistance according to GOST 13525.3-97 (ISO 1974-90). Bursting resistance according to GOST 13 525.8-86.

Example 1, 2.

Sulphate cooking of pine chips was carried out in an autoclave under the conditions: consumption of active alkali to absolutely dry wood 15% (in units of Na ₂ O), sulfide content 19, hydromodule 4, maximum cooking temperature 174 ° С, duration of reaching maximum temperature 210 min, cooking time was determined cellulose yield of 50% (example 1). Under the same conditions, cooking was carried out with AHD. AHD was used as a dispersion obtained by mixing with black liquor with a density of 1.197 g / cm ³ (example 2).

Example 3-7

Sulphate boiling of pine chips was carried out in an autoclave under conditions: consumption of active alkali to absolutely dry wood 15% (in units of Na ₂ О), sulphidity 16, hydromodule 4, maximum cooking temperature 174 ° С, duration of reaching maximum temperature 210 min, cooking duration was determined cellulose yield of 50%. The AHD was used in the form of a dispersion obtained by grinding the AHD in a mechanical mill at a rotation speed of 150 rpm. As the dispersion medium used "black" liquor with a density of 1.083-1.197 (at a temperature of 20 ° C). The duration of grinding the dispersion 30 minutes at a temperature of 70 ° C.

The results of all brews are presented in the table.

From the data presented in the table it can be seen that the mechanical grinding of AHD in black liquor with a ratio of black liquor densities: AHD from 0.71-0.9 (examples 4-6) allows, with almost the same output, to reduce the degree of delignification, reduce the amount of lack of penetration and increase the physical and mechanical properties of cellulose. In our opinion, this may be due to the fact that the grinding of AHD by cutting and abrasion in black liquor containing surfactants leads to the formation of a dispersion-resistant dispersion system that delivers and evenly distributes AHD throughout the cooking volume. It is also likely that during the interaction of particles of AHD with black liquor containing carbohydrate components, partial dissolution of AHD occurs with the formation of water-soluble derivatives of AHD, which contribute to the delignification process.

Grinding at a density ratio of black liquor: AHD 0.67 and 0.92 (examples 5 and 7) do not allow to obtain a high catalytic effect from grinding. This is due to the fact that mechanical grinding at a low or high concentration of the dispersible phase in a dispersion medium is not sufficiently effective.

Thus, the modification of AHD particles during wet mechanical grinding in black liquor of a certain concentration leads to an increase in the selectivity of the delignification process, an increase in the quality of the resulting product, a decrease in sulfide content during cooking, and a reduction in sulfur emissions.

Table
The influence of the parameters of the preparation of the catalyst on the sulfate cooking process, the consumption of the catalyst is 0.1% by weight Example No. The density ratio ρ _h. / ρ _ahd The density of the resulting dispersion, g / cm ³ The total yield of cellulose,% of a.s.d. The degree of delignification, units Kappa Lack of penetration in cellulose,% of a.s. Residual alkalinity,% Breaking length, m Tear resistance, kg Bursting resistance, kg one - - 49.5 65.3 7.8 2.6 9100 75 4.7 2 AHD - 50,0 50.8 3.4 4.1 9900 77 5,0 3 0.67 1.01 49.2 48.3 2,4 4.0 10,000 77 5,0 four 0.71 1,07 50.1 38.6 2.2 5.9 10500 79 5.2 5 0.86 1.12 50.1 37.5 2.0 5,6 10500 78 5.2 6 0.90 1.20 50,2 37.9 1.7 5.2 10600 78 5.3 7 0.92 1.25 50,0 48.8 2,4 4.1 10,000 77 5,0

Claims (1)

A method of obtaining a cellulose-containing material by alkaline treatment of cellulose-containing raw materials under the influence of temperature and pressure in the presence of a dispersion containing particles of anthraquinone-containing additives and black liquor, characterized in that the dispersion is prepared by co-grinding particles of anthraquinone-containing additives in black liquor at a density ratio of black liquor: anthraquin-containing additive 0.71-0.9: 1, respectively, until the dispersion density reaches 1.07-1.20.