A method for producing caustic soda by purifying brine

Abstract

The invention relates to a method for producing caustic soda by using purified brine. The steps include: adding a collection barrel, a vertical salt washer, a salt sinker, an old brine barrel and a cyclone to the recovery salt pipeline precipitated in the caustic soda evaporation process, and the salt slurry in the caustic soda evaporation process is collected by the collection barrel and then enters the The vertical salt washer, after cooling down, remelting and flotation with the purified brine entering from the lower part, the salt slurry is discharged from the discharge valve at the lower part of the vertical salt washer to the salt slurry tank, and the cleaned liquid is discharged from the vertical washing The overflow port of the salt tank overflows to the salt sinker, and the brine slurry in the salt sinker is discharged into the salt slurry tank, and the clear liquid rich in sodium sulfate flows back to the old brine tank, and is pumped to the salt and nitric acid cogeneration system. The salt slurry in the salt slurry tank is pumped to the cyclone by the salt slurry, and the clear liquid at the top of the cyclone flows back to the old brine tank, and the salt slurry thickened by the cyclone is transported to the salt tank for brine refining. Beneficial effects of the invention: 1. The high-nitrate mother liquor is recycled, which is environmentally friendly; 2. The power consumption and steam consumption are reduced, resources are saved, and production costs are reduced.

Description

technical field [0001] The invention relates to the technical field of brine refining technology in chlorination process, in particular to a method for producing caustic soda by using purified brine. Background technique [0002] Salt accounts for 17-20% of the production cost of caustic soda. The closer the NaCl content of the brine used to dissolve solid salt is to the NaCl content requirement of refined brine entering the electrolytic cell, the less solid salt is added until the amount of solid salt is zero. The more stable the NaCl content and impurity content of crude brine entering the brine process, the more conducive to the stable operation of the production system and the stability of product quality. However, our country is rich in salt mine resources, and the mass concentration of NaCl in brine can reach 290-310g / l. Through optimization process, under the condition of not adding solid salt, it can meet the requirements of alkali production after refining. At pres...

AI Technical Summary

Problems solved by technology

At present, the difficulty of the all-halogen soda production in the caustic soda industry is the denitrification process in the refining of brine. When the content of sulfate in refined brine is high, it will hinder the discharge of chloride ions. The discharge of sulfate in the anode of the electrolytic cell will generate oxygen, consume electric energy, and reduce the current. At the same time, both sodium sulfate and sodium chloride contain sodium ions. Due to the same ion effect, the solubility of sodium chloride is reduced, affecting the sodium chloride content of refined brine, and the decrease in the concentration of brine entering the electrolytic cell will directly affect the direct current of caustic soda production. consumption

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