SU1493613A1 - Method of producing bleaching agent - Google Patents

Abstract

The present invention relates to a method for producing a bleach for pulp bleaching and improves the quality of the bleach by increasing the rate of clarification of the pulp and increasing the durability of the resulting solution. According to the invention, the chlorination of milk of lime with chlorine-containing gas is carried out in the presence of carnallite dust, which is introduced before the content of 1.0-10.00 g / l of HCI in the pulp. Before clarification, the resulting pulp is diluted with water to 40-80 g / l of active chlorine. As the chlorinating gas, the exhaust gases of magnesium production by electrolysis are used, and the source gases of the second stage of carnallite dehydration, supplied in a volume ratio of (1-3): 1, are used as a source of carnallite dust. The introduction of carnallite dust and dilution of the pulp before clarification makes it possible to increase the rate of clarification of the pulp by a factor of 12–18 and improve the solution stability during storage and transportation by the amount of suspended sediment by 5.5–7 times, by loss of active chlorine about 5 times. 1 hp f-ly, 3 tab.

Description

The invention relates to the chemical industry and can be used in the preparation of bleaches for bleaching. Cellulose.

The purpose of the invention is to improve the quality of the bleach by increasing the rate of clarification of the pulp and increasing the durability of the resulting solution.

The method is implemented as follows.

Carnallite dust is added to the milk of lime supplied to the purification of waste gases containing chlorine and hydrogen chloride (for example, gases from the electrolysis shop Magnesium 131) to a content of 1-10 g / l KS1. Carnallite dust can be introduced in the proposed dosage into the pulp after gas cleaning. The pulp obtained from gas scrubbers is diluted with water to 40–80 g / l of active chlorine, stirred for 30–40 min, and transferred to clarification, which can be carried out by filtration or suction with decantation. The clarified portion of the pulp is a bleach and can be used to bleach the pulp.

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The method was developed and tested on industrial pulps from gas purifiers of magnesium production, Carnallite dust was introduced into the pulp obtained from gas purification, before its dilution (experiments were performed in laboratory conditions), into the milk of lime fed to the gas purification, and during joint cleaning gases (experiments performed on promyagashennoy installation).

At the same time, the dosage of carnallite changed within certain limits, controlling the concentration of KC1 in the pulp. Then the pulp was diluted with water to different contents of active chlorine, stirred for 30 minutes and settled, controlling the sludge time and durability of the clarified bleach solution according to the loss of chlorine chlorine and the amount of the separated solid phase during its storage for 15 days.

Experimental data are presented in table 1,

As can be seen from the above data, the introduction of carnallite dust to a content of 0.6-1.0 g / l KS1 in the pulp improves the durability of the clarified solution (example 1 by a known method and examples 2 and 3). With an increase in the amount of puppy to a content of 10 g / l KCl in the pulp, the rate of clarification is significantly accelerated and the solution stability is improved (examples 4 and 5). When the pulp contains more than 10 g / l KC1 (14 g / l), all indicators improve slightly.

When combining the addition of carnallite dust and diluting the pulp with water to a concentration of 40-80 g / l of active chlorine, the monitored process indicators are significantly improved (examples 7-10), while the separate introduction of carnallite dust upon dilution of the pulp improves the process performance much weaker (examples 5, 8 and 11).

Experiments according to examples 12-15, carried out under production conditions, prove the validity of introducing carnallite dust both at the gas cleaning stage into the milk of lime (examples 12 and 13) and during the joint purification of electrolysis waste gases: and the second stage of dehydration.

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It is optimal to introduce carnallite dummy. With a joint purification of magnesium production gases by electrolysis, containing chlorinating gas, and second-stage waste gases, carnallite is supplied in a volume ratio of 1-3: 1.

In tab. 2 gives the composition of the gases of magnesium electrolysis and the second stage of carnallite dehydration. In tab. Figure 3 shows the composition of the dust contained in the gases of magnesium electrolysis and the second stage of carnallite dehydration.

The introduction of carnallite dust and dilution of the pulp before clarification makes it possible to increase the rate of clarification of the pulp by a factor of 12–18 and improve the solution stability during storage and transportation by the amount of suspended sediment by 5.5–7 times, by the loss of active chlorine by about 5 times.

An increase in the durability of the bleach obtained makes it possible to eliminate the blockage of transport routes and the container of suspended suspension from the solution, as well as improve the weediness index of the pulp bleached by the bleach obtained by the proposed method.

Claims (1)

1. A method for producing a calcium hypochlorite bleach, including chlorination of milk of lime with a chlorinating gas and clarification of the resulting pulp, characterized in that, in order to increase the quality of the bleach by increasing the rate of clarification of the pulp and increase the durability of the resulting solution, chlorination is carried out in the presence of carnallite pichy, which is injected to a content of 1.0-10 in the pulp, Og / LKS1, and before clarification, the pulp is diluted with water to 40-80 g / l of active chlorine, 2, a method according to claim 1, characterized in that the exhaust gases from the production of magnesium by electrolysis are used as the chlorinating gas, and the source gases of the second stage of carnallite dehydration are used as a source of carnallite pypy, 1-3: 1 , tblna 1