Process for removing sodium chloride from salt mud produced in chlor-alkali production

Abstract

The invention discloses a process for removing sodium chloride from salt mud produced in chlor-alkali production, and belongs to the technical field of environmental protection control. The process ischaracterized by comprising the process steps: (1) 0.3%-1.3% by mass of polyacrylamide is added into a salt-mud-containing salt solution, the salt mud and the salt solution are separated through an automatic centrifugal separator, and the salt mud is transferred into a salt washing pool; (2) water is added into the salt mud in the salt washing pool to stir and wash, wherein the mass ratio of thesalt mud to the water in the salt washing pool is (12 to 15):(83 to 86); (3) the mixture is conveyed to a plate-and-frame filter press to be subjected to filter pressing, and liquid obtained through filter pressing is directly discharged, wherein the filter pressing pressure is 0.75-0.85 MPa, and the filter pressing time is 120-150 min; and (4) the salt mud after filter pressing is used as a cement production raw material or used for plant cultivation. The sodium chloride in the salt mud can be completely removed in a washed mode, thus the salt (NaCl) content in the salt mud is decreased to be1% or below, the waste discharge pressure is reduced, and clean production of the chlor-alkali industry is achieved.

Description

technical field [0001] The invention discloses a sodium chloride removal process for salt mud produced in chlor-alkali production, which belongs to the technical field of environmental protection treatment. Background technique [0002] In the production of chlor-alkali, a large amount of salt mud will be produced from refined brine, the main components are as follows: calcium carbonate 5~20%, magnesium hydroxide 10~15%, sediment and other insoluble matter 8~12%, sodium chloride 13~15%, water 30~35%, other 3~5%. Due to the high salt content of salt mud produced by chlor-alkali, it cannot meet the environmental protection discharge requirements and cannot be discharged as general waste, which seriously restricts the clean production of chlor-alkali. [0003] The existing technology is unreasonable. The existing technology uses a mud washing bucket to wash salt, and a plate and frame filter press is used to directly filter and discharge the salty mud brine. It is impossible t...

AI Technical Summary

Problems solved by technology

Due to the high salt content of salt mud produced by chlor-alkali, it cannot meet the environmental protection discharge requirements and cannot be discharged as general waste, which seriously restricts the clean production of chlor-alkali

[0003] The existing process technology is unreasonable. The existing process uses a mud washing bucket to wash salt, and a plate and frame filter press is used to directly filter and discharge the salty mud brine. It is impossible to wash all the sodium chloride in the salt mud. Adding water to the medium will only remove 50% of the total amount of sodium chloride, which still cannot meet the discharge standards.

At the same time, the investment of the mud washing bucket is large, the effect is poor, and the operation is complicated. Now most of the chlor-alkali production enterprises have eliminated this process.

However, there is no new technology to solve the problem of high salt content in salt mud in existing chlor-alkali production enterprises.

As a result, the salt sludge in chlor-alkali production has a high salt content and cannot be discharged or utilized directly. It can only be discharged in an orderly manner, and clean production cannot be realized.