Method for removing SO4<-2> in brine

Abstract

The invention relates to a method for removing SO4<-2> in brine. The method comprises the following steps of: adding calcium chloride and magnesium sulfate into a bittern at 0 to 50 DEG C for reaction to generate calcium sulfate and magnesium chloride, wherein the adding amount of calcium chloride is the equivalent weight of magnesium sulfate in the bittern, and the content of the reacted magnesium sulfate in the bittern is required to be below 5 g/L; then evaporating, keeping warm, precipitating, cooling for crystallisation, decomposing and washing to obtain a potassium chloride product, wherein the content of SO4<-2> in the potassium chloride product produced by using master sauce as a material is below 2.8%; removing SO4<-2> from the bittern; entering the procedures of evaporating, keeping warm, precipitating, cooling for crystallisation, decomposing and washing to obtain the potassium chloride product, wherein a brine-mixing step can be omitted. Only sodium chloride is separated out in the steps of evaporating, keeping warm and precipitating. Because the particle of sodium chloride is bigger, solid-liquid separation is easy, potassium chloride is lost very little; the defect of losing a large amount of potassium chloride due to separating magnesium sulfate monohydrate in the prior art is avoided, and the recovery rate of potassium chloride is improved.

Description

technical field [0001] The invention relates to a method for removing SO in brine 4 -2 method, especially related to the SO in the sun-dried salt attached to the brine (hereinafter referred to as bittern) 4 -2 method of removal. The composition of bittern is simplified, the extraction of salts such as sodium chloride, potassium chloride and magnesium chloride in bittern is facilitated, and the recovery rate of salts such as potassium chloride is greatly improved. Background technique [0002] In the salt chemical industry that uses bittern produced by sun-dried salt as raw material, the main components of bittern are: magnesium chloride, sodium chloride, potassium chloride, magnesium sulfate, etc. Due to the presence of magnesium sulfate in bittern, the extraction process of the above salts is complicated, the extraction rate is low, and the production cost and energy consumption increase. The process flow is briefly described as follows: [0003] Bitter bittern—(mixin...

AI Technical Summary

Problems solved by technology

Due to the presence of magnesium sulfate in bittern, the extraction process of the above salts is complicated, the extraction rate is low, and the production cost and energy consumption increase