Alkali slag recovery and treatment method in soda ash production

Abstract

The invention discloses a method for recovering and treating alkali slag in soda ash production, comprising the following steps: (1) after separating and dehydrating the alkali slag, performing ammonia distillation reaction with hot mother liquor in an ammonia distillation tower to control the liquid pH in the ammonia distillation tower Value is below 9.0, and the ammonium chloride in keeping mother liquor is excessive; (2) the semi-ammonium mother liquor after mother liquor distills ammonia in step (1) is transported in another ammonia distillation tower, adds milk of lime to distill ammonia, each half The amount of milk of lime added to the ammonium mother liquor is 0.13-0.19m3; the ammonia distillation is completed until the ammonia index in the waste liquid in the tower is <50mg / l. (3) After the solid-liquid separation of the waste liquid after the second ammonia distillation, the alkali slag is dehydrated; the ammonia steamed from the top of the ammonia distillation tower in the two ammonia distillations is transported to the ammonia absorption tower for recovery. In the alkali slag treatment method of the present invention, after the alkali slag is subjected to the secondary ammonia distillation reaction, about 80-85% of the solids have participated in the chemical reaction. After dehydration, the solid amount (wet basis) is reduced to 12.3% of the solid amount before the ammonia distillation. %the following.

Description

technical field [0001] The invention relates to the technical field of treatment of three wastes in chemical production, in particular to the treatment technology of alkali slag in soda ash production. Background technique [0002] In the production of soda ash by the ammonia-soda method, a large amount of ammonia distillation waste liquid is produced in the ammonia recovery process, and the waste liquid carries a large amount of alkali slag. At present, there is no economical and effective treatment method for alkali slag in the world. Most of the known technologies use the method of transporting the waste liquid to the slag yard, natural settlement of the alkali slag, and stacking for storage. Because the solid particles of the alkali slag are extremely small, with an average particle size of 10 μm, it is determined that the alkali slag will naturally settle down to 80% of the water content, and will not continue to settle. Therefore, this treatment method occupies a larg...

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Problems solved by technology

This kind of treatment idea can achieve the purpose of waste utilization, but these processes are generally difficult to implement, with complicated process steps, high treatment costs, low purity and poor quality of the prepared products, which can only be used for engineering purposes, and the added value of products is low.

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