The method of obtaining cotton cellulose

 

The invention relates to obtaining cotton cellulose from cotton linters and can be used in the pulp and paper industry, the chemical industry to obtain nitrocellulose, cellulose acetate, carboxymethyl cellulose, microcrystalline cellulose, copper ammonia fiber, cardboard and in the powder industry. Cotton cellulose loose, clean and moisten with hot caustic soda solution at a temperature of 60-80oC. are boiling in caustic soda solution with added as an emulsifier of sulfinol when module 1:13-1:8 and a temperature of 125-160oC for 3-6 hours and Then subjected to bleaching in sodium hypochlorite at a concentration of active chlorine in the bleaching solution of 0.7-2.0 g/l at a temperature of 20-40oWith over 1,0-2,5 hours followed by kislovka in sulfuric acid leaching the mass of softened water with hardness not more than 0.1 EQ/l, with a mass fraction of iron is not more than 0.03 mg/l and subjected to pressing and drying. Drying is carried out in two Aeropostale dryer, consisting of sections, when the temperature in the first section 160-175oWith the second - 90-100oSince, in the third - 90-100oWith the fourth 75-80oWith to a moisture content of 2-10%. Hydrodynamic D/chr/8804.gif">2060, when the relationship dm/D~0,46; H/D~1,8; D/d~2,1, where Re is the number of Reynolds; dm- the diameter of the agitator; D - diameter Chan; H - height of the layer of pulp in the VAT. The technical result is to obtain cotton cellulose required quality environmentally safe method of different varieties of cotton Linter with less time and simple equipment design. 1 Il., table 2.

The invention relates to a method for production of cellulose, in particular to a method for cotton cellulose from cotton linters, and can be used in the pulp and paper, chemical industries, to obtain nitrocellulose, cellulose acetate, carboxymethyl cellulose, microcrystalline cellulose, copper ammonia fiber, cardboard and in the powder industry.

A method of obtaining cotton cellulose copyright testimony 829750, CL 3 D 21 C 5/00, USSR, 1979

The method includes skipping purified nitrogen gas through a 2% solution of caustic soda at a temperature of 85oC for 5 h, the boiling of cotton Linter in 2% caustic soda solution with the addition of surfactants (OP-7) at a temperature of 140-150oC for 1-4 h and the pressure is Holocene cotton cellulose due to the passing gaseous nitrogen through a 2% solution of caustic soda. In addition, gaseous nitrogen irritating effect on the mucous membranes of the respiratory tract of staff. The invention is not specified further processing of cotton cellulose. This method will use cotton linters I, II varieties.

A method of obtaining cotton cellulose copyright testimony 1251597 A1, CL 6 D 21 5/00, USSR, 1984

The method includes pre-wetting water cotton Linter by steaming at a pressure of 0.11 to 0.13 MPa, treatment with ozone-air mixture in the gas phase under vigorous stirring, at a flow rate of ozone-air mixture 15-20 mg/l for 15-30 min, boiling in 2% NaOH solution at a temperature of 95-100oC for 1 h, rinsed hot and cold water for 5 min, kislovka 0.3% solution of sulfuric acid for 15 min, rinse with cold water twice for 5 min to pH 6-7, extraction and drying in the air.

The disadvantage of this method is air drying, leading to a significant increase in time to process, the use of ozone-air mixture, is harmful to the body, providing irritant effect on the mucous membranes of the respiratory tract, until the swelling of the lungs, causing dizziness, headache is wet.

A method of obtaining cotton cellulose copyright testimony 308133, CL 6 D 21 5/00, USSR, 1976

The method of obtaining cotton cellulose from cellulose-containing raw material such as cotton Linter is consistent double the processing of raw materials by hot alkali solution at a temperature of 95-100oWith, bleaching by treatment with sodium hypochlorite, followed by treatment with sulfuric acid, washing with selection of the target product known methods. To simplify the reaction mass after the treatment with hot alkali solution sequentially treated with alkali solution with a concentration of 1.0-1.2% and 0.5 to 0.7% and hot water, process lead flow-irrigation method. Washing with water is carried out until a neutral reaction, then pressing and drying.

The disadvantage of this method is the long process of obtaining cotton cellulose, consisting of two processing pulp, the absence of emulsifier, affecting the cooking process, reducing the viscosity of the pulp, providing uniformity of pulp viscosity in different zones in the digester, the penetration of reagents into the pores of the cellulose. Not specified specific temperature and the WMD method is a method of obtaining cotton cellulose (Zabelin L. C., Secondyou A. P., Postnikov C. K. Cotton cellulose. M, CLIENTI, 1976, S. 202-252).

The method of obtaining cotton cellulose from cellulose-containing raw material includes the following stages of the technological process: raking, cleaning, wetting the cotton Linter in caustic soda solution of 1.2 to 3.8% at a temperature of 60-80oC, boiling in caustic soda solution of 1.2% to 3.8% for 4-8 hours at a temperature of 130-150oWhen the module from 1: 8 to 1:11 with the addition of the emulsifier (a solution of rosin soap, detergents "Neal", "Progress", contact Petrov) at an operating pressure up to 0.7-0.8 MPa, washing twice with hot water with a temperature of 60-80oWith, then cold. Each washing is carried out at a running agitators for 25-30 minutes Bleaching is carried out in sodium hypochlorite with a concentration of active chlorine 0.35 g/l at a temperature of 60-80oWith under stirring for 0.5-4 h Then washed twice with cold water for 1-2 hours and are kislovka in sulfuric acid concentration of 0.5-2 g/l for 0.5-2 h, then washed twice with cold water for 30 min with stirring until neutral, mixed General of the party, squeezed to a moisture content of 55-60%. Drying cotton cellulose to a moisture content of 10-12% is carried out in trichromacy Aerovent 60-80oC. Then Packed and Packed. Washing implement process water having a hardness of not more than 2 mgmEq/l, the mass fraction of iron is not more than 0.3 mg/L.

The disadvantage of this method is the long process of obtaining cotton cellulose. For washing the used process water having greater rigidity, which affects the quality and time of washing the pulp. The pulp itself is the adsorbent, which affects the whiteness of cotton cellulose. Boiling of cotton Linter are with the addition of the emulsifier (a solution of rosin soap, detergents "Neal", "Progress", contact Petrova), which is not enough to wet cotton linters, which lengthens the time and quality of cooking.

The objective of this invention to provide a cotton cellulose required quality environmentally safe method of different varieties of cotton Linter with less time and simple equipment design technology.

The problem is solved due to the fact that in the known method of obtaining cotton cellulose from cellulose-containing raw material, including raking, cleaning, soaking in a hot caustic solution is in the sodium hypochlorite, kislovka in sulfuric acid leaching the mass with water after each operation, extraction and drying, the cooking is carried out at module 1:13-1:8 at a temperature of 125-160oC for 3-6 h, and as an emulsifier, a mixture of sodium salts of alkylbenzenesulfonic (solganol), the bleaching is carried out at the concentration of active chlorine in the bleaching solution of 0.7-2.0 g/l at a temperature of 20-40oC for 1.0 to 2.5 h, and washing the masses provide softened water having a hardness of not more than 0.1 mgmEq/l, with a mass fraction of iron is not more than 0.03 mg/l, the drying is carried out in two Aeropostale dryer, consisting of sections, when the temperature in the first section 160-175oWith the second - 90-100oSince, in the third - 90-100oWith the fourth 75-80oWith to a moisture content of 2-10%, in addition, hydrodynamic process for the bleaching of pulp in the VAT must satisfy the conditions 19500Re20600, in the case of dm/D~0,46; H/D~1,8; D/d~2,1, where Re is the number of Reynolds; dm- the diameter of the agitator; D - diameter Chan; H - height of the layer of pulp in the VAT.

In used as raw cotton linters (GOST 3818.0-72).

The method is as follows.

First providedunder-cyclone 1, where is wetting its 1.2 to 3.8% sodium hydroxide solution at a temperature of 60-80oWith that allows you to increase the load of the digester through the sealing material. Moistened with a solution of cotton lint from the hopper of the cyclone is discharged to the screw 2, next to the digester 3. Cooking lint is carried out at a temperature of 125-160oWith in sodium hydroxide solution (lye) concentration of 1.2% to 3.8% with the addition of emulsifier - sultanol (mixture of sodium salts alkylbenzenesulfonic) module when cooking from 1:13 to 1:8. While cooking is a continuous circulation of the cooking solution in the "boiler - heater for uniform wetting of lint in caustic soda solution. Cooking time is determined by the type and viscosity of the produced pulp and ranges from 3 to 6 h at a working pressure of not more than 0.5 MPa. At the end of cooking the pulp from the boiler is blown in will let drain 4 to remove alkali and washing. In sage is the first washing twice with hot softened water with a temperature of 60-90oC for 30 min and cold softened water with constant stirring for 10-20 minutes Washing is performed to remove the dissolved and emulsified during cooking husk, seeds and ashes. the logo colors.

Hydrodynamic process for the bleaching of pulp is determined by the type of mixing device, the rotational speed of the agitator bleach Chan.

The bleaching of pulp is carried out at a temperature of from 20 to 40oWhen the pH of the solution from 10 to 11 within 1.0 to 2.5 h when operating the mixer. The concentration of active chlorine in the bleaching solution of 0.7-2.0 g/L. the Process of bleaching cellulose contributes to the improvement of the reactivity and viscosity reduction of the cotton cellulose. Later in the VAT is used to wash pulp cold softened water for 15-30 minutes After the end of the drain wash water in the tub download the sulfuric acid concentration of 1-4 g/l for the destruction of the remaining cellulose sodium hypochlorite and alkali, excess ash. The duration of kislovka is 30-60 minutes After kislovka pulp mass is washed twice with cold softened water for 30 min to achieve in the wash water to the lack of active chlorine and pH from 7 to 8. Then after draining the waste water the pulp with cold softened water and sent to the mixer 6 mixes the General parties with the aim of obtaining volume batch and achieve uniformity in the physico-chemical characteristics of the drying. Drying is carried out in two Aeropostale the dryer 8, consisting of two sections each, when the temperature in the first section 160-175oWith the second - 90-100oSince, in the third - 90-100oWith the fourth 75-80oC.

Cotton cellulose after videoteenage unit picked up a hot air stream passes through two sections of the first Aeropostale dryer, an intermediate drum, served in a hot air stream carrying the cotton cellulose second Aeroporto dryer. Humidity cotton cellulose at the first stage is achieved 40-55%, when passing through the second stage is 2-10%.

The viscosity of cotton cellulose depends on the modes of treatment of cellulose with sodium hydroxide solution in the digester, the pulp bleaching. Depending on this, we obtain a pulp of the desired brand.

The proposed method for cotton cellulose allows you to get the cotton cellulose required quality of different varieties of cotton Linter at a relatively lower cost over time.

Changing modes of cooking (temperature from 125 to 160oAnd the cooking time 3 to 6 hours), it is possible to vary the properties of cotton cellulose depending on the grade and quality of hlopkosejushchih wetting of the fibers and to facilitate the transfer of contaminants from the fiber, while the use of two-stage Aeropostale dryer consisting of two sections each, for drying cotton cellulose allows uniform drying, thereby to avoid getting burnt, burnt pulp, the use of softened water for leaching, contributes to obtaining cotton cellulose desired whiteness.

For optimization of the mode of bleaching experimental work. A summary of the parameter that determines the quality of cotton cellulose, taking into account the hydrodynamics of the process phase bleaching, accepted criterion of Reynolds - Re
19500Re20600,
when relations
dm/D~0,46;
H/D~1,8;
D/d~2,1,
where Re is the number of Reynolds;
dm- the diameter of the agitator;
D - diameter Chan;
H - height of the layer of pulp in the VAT.

The use of the hydrodynamic modes of the bleaching of pulp in bleaching Chan promotes uniform effect of sodium hypochlorite on pulp throughout the volume of the VAT, which facilitates the removal of nitrogen-containing residues, wax and other recellular impurities.

Obtained in this way cotton cellulose fully meets the state standard 5 the EMA receipt cotton cellulose is shown on the drawing.


Claims

The method of obtaining cotton cellulose, including raking, cleaning, wetting hot caustic soda solution at a temperature of 60 - 80oC, boiling in caustic soda solution with the addition of the emulsifier, the bleaching in sodium hypochlorite, kislovka in sulfuric acid leaching the mass with water after each operation, extraction and drying, characterized in that the cooking is carried out at module 1: 13-1: 8, at a temperature of 125-160oC for 3-6 h, and as an emulsifier, a mixture of sodium salts of alkylbenzenesulfonic - sultanol, the bleaching is carried out at the concentration of active chlorine in the bleaching solution of 0.7-2.0 g/l at a temperature of 20-40oC for 1.0 to 2.5 h, and washing the masses provide softened water having a hardness of not more than 0.1 mgmEq/l, with a mass fraction of iron is not more than 0.03 mg/l, the drying is carried out in two Aeropostale dryer, consisting of sections, when the temperature in the first section 160-175oWith the second - 90-100oSince, in the third - 90-100oWith the fourth 75-80oWith to a moisture content of 2-10%, in addition, hydrodynamic process for the bleaching of pulp in the VAT must satisfy the conditions:
19500Re

 

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