Preparation technique of high-purity potassium chloride

Abstract

The invention relates to a preparation technique of high-purity potassium chloride, which comprises the following steps: (1) adding a hydrochloric acid solution into agricultural potassium chloride, stirring, and carrying out solid-liquid separation; (2) adding a KOH solution into the solid phase, dissolving by heating, keeping the temperature, and filtering to obtain a high-temperature oversaturated potassium chloride mother solution; (3) adding a sodium hexametaphosphate solution into the high-temperature oversaturated potassium chloride mother solution, and stirring until the mother solution is cooled to room temperature, thereby obtaining a potassium chloride slurry; and regulating the mass percent of the potassium chloride crystal in the potassium chloride slurry, carrying out cyclone grading, and drying the obtained potassium chloride coarse crystal to obtain the high-purity potassium chloride. The technique has the advantages of energy saving, consumption reduction, short technical process, simple equipment, low investment, high product purity (at least 99.5%), high potassium chloride yield (at least 95.5%) and favorable potassium chloride crystallinity. The potassium chloride with the particle size of 1mm above accounts for 70 wt% of the total potassium chloride, and the impurity content is lower than 0.3%; and thus, the potassium chloride satisfies the requirements in GB25585-2010.

Description

technical field [0001] The invention relates to a preparation process of inorganic salts, in particular to a process for preparing high-purity potassium chloride by using agricultural potassium chloride. Background technique [0002] High-purity potassium chloride is an important raw material for medicine and food additives, and is also a raw material for the manufacture of high-purity potassium hydroxide, potassium sulfate, potassium nitrate and potassium chlorate. As one of the main components of low-sodium salt, the dosage is huge. Low-sodium salt is a new generation of edible salt with health care effects. Long-term consumption is beneficial to the balance of sodium, potassium, magnesium and other ions in the human body, and has obvious effects on preventing high blood pressure. Effect. [0003] At present, most of the high-purity potassium chloride that can be used in food and pharmaceutical grades in my country is obtained by removing impurities from agricultural pota...

AI Technical Summary

Problems solved by technology

At present, most of the production processes adopt the hot-melt crystallization process, such as the process disclosed in CN102241408 A, which uses the difference in the solubility of impurity ions and potassium chloride to remove impurities, but the effect is not ideal, and a large amount of water needs to be consumed for evaporating a large amount of water. Energy; CN101683987A discloses that the KCl supersaturated mother liquor obtained by thermal melting is cooled to below zero for cooling and crystallization to obtain high-purity potassium chloride. Then through the second effect decompression evaporation crystallization, high-purity potassium chloride product is obtained, but the crystal particle size of potassium chloride is not controlled; CN102874847A discloses the scheme, is to utilize saturated potassium chloride slurry to add potassium chloride crystal A kind of method, forms thick slurry, then the method of cooling crystallization, obtains high-purity potassium chloride product, and the crystal particle of 0.5 mm or more in the potassium chloride product obtained by this process accounts for more than 80%, but needs to add a large amount of potassium chloride Seed crystals, and the requirements for crystal particles are more stringent

At present, agricultural-grade potassium chloride is mostly directly obtained by flotation, and amines are mostly used as flotation agents in the flotation method. Therefore, the amines in agricultural-grade potassium chloride are far from food-grade and Pharmaceutical grade requirements, but few technologies describe how to remove such substances