Method for preparing low sodium low potassium content carnallite

Abstract

The invention relates to a method for preparing potassium carnallite with low sodium content, which is characterized in that after being preheated through a preheating tank, saltern potassium carnallite solid materials and a circulating mother liquor are added into a heating tank for heating and stirring so as to ensure that most sodium chloride is crystallized and separated out; and a dissolvingmother liquor flows into a depositing tank for depositing and after a deposited overflow saturation dissolving mother liquor is evaporated in vacuum, cooled for crystallizing and deposited and separated, the artificial potassium carnallite with low sodium content is obtained. The method has the advantages of simple process, easy operation and low cost. The chemical compositions of the potassium carnallite prepared by the method comprise: 32 to 33 percent of MgCl2, 23 to 24 percent of KCl, less than or equal to 6 percent of NaCl and 38 to 40 percent of H2O. The prepared potassium carnallite has the advantages that the potassium carnallite meets the requirement on raw materials of electrolysis for smelting magnesium, sufficiently utilizes abundant salt lake resources in the northwest area of China, relieves the pressure that magnesite resources used by electrolytic magnesium are limited and simultaneously improves the grade of potassium chloride used as a potash fertilizer in waste electrolyte.

Description

technical field [0001] The invention relates to a method for preparing potassium carnallite. Background technique [0002] At present, in the domestic production plants of electrolytic magnesium as commercial magnesium, most of them use magnesite, a unique resource in my country, as raw material to produce metallic magnesium through chlorination and electrolysis. With the development of refractory material industry and magnesium metallurgy industry, the demand for magnesite resources is also increasing, which affects the sustainable development of my country's limited magnesite resources. However, there are rich salt lake resources in Northwest my country, which contain a large amount of magnesium salts. Therefore, it is imperative to make full use of the rich salt lake resources in Northwest my country - Yantian potassium carnallite, and develop my country's electrolytic magnesium industry and potash fertilizer industry. However, if the dehydration of potassium carnallite ...

AI Technical Summary

Problems solved by technology

When the potassium carnallite with high sodium chloride content is electrolyzed, it not only reduces the active ingredient magnesium chloride in the electrolyte, but also increases the circulation volume of the electrolyte, which increases the amount of sodium chloride in the spent electrolyte potassium chloride, affecting grade of potassium chloride

[0003] In the prior art, the patent publication number CN1275531 discloses a method for directly producing low-sodium, high-quality carnallite. In this method, carnallite brine and bischofite are used as raw materials, and bischofite is required to be relatively high. Pure, otherwise bischofite needs to be dissolved separately to the required degree of Baume, then the insoluble matter is removed, and the clear liquid is then mixed with carnallite brine to obtain low-sodium carnallite, which makes the process The process becomes more complicated

And when the bicholorite is dissolved to the required Baume degree, if you want to remove the insoluble part, it will inevitably cause the loss of the clear liquid (caused by the higher content of the adsorption mother liquor after filtration), thus causing the magnesium bichloride The consumption of carnallite increases, and the cost of low-sodium carnallite increases

The patent with publication number CN1608995 discloses a method for producing low-sodium carnallite by mixing brine, and the patent with publication number CN1751999 discloses a method for producing low-sodium carnallite by adding halogen. Low-sodium carnallite is obtained by this method, which has the disadvantages of complex process, large equipment investment, and high technical level of management personnel, and the carnallite obtained according to the patent method of CN1608995 mainly contains magnesium sulfate salt, which is not conducive to the application in electrolytic magnesium smelting. aspect

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