Method for preparing potassium chloride from carnallite raw ore

Abstract

The invention provides a method for preparing potassium chloride from carnallite. The low-sodium carnallite slurry is decomposed and crystallized for the first time in a first crystallizer 8a, magnesium chloride in carnallite is transferred into a liquid phase, part of potassium chloride transferred into the liquid phase is crystallized and separated out, and underflow of the first crystallizer 8acontains separated-out potassium chloride and undecomposed carnallite and sodium chloride particles. The underflow of the first crystallizer 8a is decomposed and crystallized in a second crystallizer8b, sodium chloride in carnallite is transferred into a liquid phase, part of potassium chloride transferred into the liquid phase is crystallized and separated out, and the underflow of the second crystallizer 8b contains separated potassium chloride and undecomposed carnallite and sodium chloride particles. The underflow of the second crystallizer 8b is screened, the oversize product comprisesundecomposed carnallite and sodium chloride particles, and a potassium chloride product is generated from the undersize product. The oversize product is crushed, wherein the crushed oversize product is used for generating the low-sodium carnallite slurry. The grade of potassium chloride is guaranteed, and meanwhile, the recovery rate of carnallite is greatly increased.

Description

technical field [0001] The invention relates to a method for preparing potassium chloride from carnallite raw ore, in particular to a method for preparing potassium chloride from large-grain carnallite raw ore. Background technique [0002] Potassium resources in China widely exist in remote areas such as Qinghai, among which the reserves in Qinghai account for more than 50% of the national reserves, and the representative resources are salt lake resources. At present, due to the continuous expansion of potash fertilizer production scale in the Salt Lake area and the gradual release of production capacity, starting from the brine mining area, there is a trend of shortage of raw brine and a decrease in potassium content of raw brine resources year by year. Along with the use of large-grain carnallite raw ore (hereinafter referred to as raw ore) in recent years, the content of sodium chloride in the raw ore increases, causing potassium fertilizer production enterprises to prod...

AI Technical Summary

Problems solved by technology

[0007] This process can effectively reclaim undecomposed large-grain carnallite by setting recovery crystallizer 11, and improve the recovery rate of potassium chloride, but because the sodium chloride of large grain is insoluble than carnallite, the material at the bottom of reclaim crystallizer 11 There will still be incompletely dissolved large particles of sodium chloride in the slurry (underflow), reducing the grade of potassium chloride

If reclaiming crystallizer 11, add excessive water and make sodium chloride particle dissolve, can cause most of potassium chloride to transfer to liquid phase, have only a small amount of potassium chloride to separate out, the potassium chloride that transfers to liquid phase is with recovery crystallizer The overflow discharge of 11 causes the loss of potassium chloride and reduces the utilization rate of carnallite

[0008] The purpose of the present invention is to improve the above-mentioned prior art to solve the problems of low potassium chloride grade and low utilization rate of carnallite when producing potassium chloride from large-grained carnallite raw ore

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