Method and system for preparing carnallite from crude potassium mother liquor

Abstract

The invention relates to a method and system for preparing carnallite from crude potassium mother liquor, and the method comprises the following steps: 1, adding fresh water to dilute crude potassiumwashing mother liquor to obtain a first solution, determining the amount of the added fresh water by adopting a Na <+>, K <+>, Mg <2+> / / Cl-H2O simple quaternary system phase diagram, and enabling thefirst solution and old brine not to be salted out before brine mixing, 2, adding old brine into the first solution until the content ratio of magnesium chloride to potassium chloride is greater than or equal to 9: 1 to obtain a solid-liquid mixture containing solid-phase sodium chloride and a second solution, and 3, tedding the second solution to obtain the high-quality carnallite. The crude potassium washing mother liquor is diluted, so that the concentration of potassium chloride is reduced. Therefore, after the old brine is added, no potassium chloride is separated out from the brine-mixedmother liquor, the loss of potassium separated out in advance can be effectively avoided, the resource recovery efficiency is improved, and high-quality carnallite is obtained.

Description

technical field [0001] The present invention generally relates to the field of salt chemical industry, and more specifically relates to a method and system for recycling crude potassium washing mother liquor. Background technique [0002] The process of preparing potassium chloride from salt lake brine mainly includes drying brine to obtain carnallite, making pulp from carnallite, flotation or reverse flotation, decomposing crystallization, screening and dehalogenation to obtain crude potassium, and then treating crude potassium Washing and dehalogenation are carried out again to obtain refined potassium, that is, potassium chloride with higher purity. After the carnallite is precipitated out of brine, the remaining liquid phase contains a large amount of magnesium chloride, a small amount of sodium chloride and potassium chloride, which is usually called old brine. [0003] Crude potassium is a potassium chloride semi-finished product containing a small amount of soluble i...

AI Technical Summary

Problems solved by technology

For example, returning the crude potassium washing mother liquor to the decomposing crystallizer to decompose carnallite, but due to the high content of sodium chloride in the crude potassium washing mother liquor, returning the crude potassium washing mother liquor to the decomposing crystallizer will cause chlorination in the decomposing crystallizer. The enrichment of sodium affects the quality and yield of potassium chloride products

For another example, the crude potassium washing mother liquor is returned to the salt field to dry carnallite. However, since the magnesium and potassium in the crude potassium washing mother liquor are relatively low, during the drying process, potassium halite will be precipitated first, forming carnallite and potassium halite When the mixed ore is produced by flotation or reverse flotation, the yield of potassium chloride will be greatly reduced

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