Reverse floatation-cold crystallization process for producing potassium chloride

Abstract

The reverse floatation and cold crystallization process for producing potassium chloride includes the following four steps: 1. reverse floatation to prepare low sodium carnallite; 2. decomposing low sodium carnallite in fresh water, crystallizing, centrifugally filtering and drying to prepare potassium chloride product; 3. microporous membrane filtering to recover fine potassium chloride crystal, dissolving, returning to potassium chloride crystallizer for secondary crystallization to prepare potassium chloride; and 4. returning the bittern for reuse. The process has potassium chloride yield up to 80 %, great potassium chloride crystal granularity and high product quality, and is suitable for industrial production.

Description

technical field [0001] The invention relates to a production method of potassium chloride, in particular to a reverse flotation-cold crystallization potassium chloride production method combining fine grain elimination and membrane coupling, and belongs to the field of inorganic chemical industry. Background technique [0002] Potassium chloride production process has experienced decades of development and continuous technological progress, during which many production methods for the production of potassium chloride have emerged, such as: salt field recrystallization method, re-election method, etc., all due to the environment, conditions, For reasons of climate, technology, etc., some of them were just given up after experiments or pilot tests, but did not realize industrialized production. The four production methods of cold decomposition forward flotation, reverse flotation cold crystallization, thermal dissolution and brine mixing have not only realized industrial produ...

AI Technical Summary

Problems solved by technology

[0027] The purpose of the present invention is to make a major improvement on the defects of poor product quality and low utilization rate of potassium chloride in the existing reverse flotation-cold crystallization process. The recovered nanofiltration membrane permeate with high sodium chloride content is used to recover the fine crystals of potassium chloride through the microfiltration membrane when the carnallite concentrate is coldly decomposed into magnesium chloride and crystallized to produce potassium chloride. The crystallization mother liquor is filtered through a nanofiltration membrane, and the dialysate dissolves fine crystals of potassium chloride to prepare a saturated solution and returns it to the crystallizer to control the concentration of potassium chloride to prevent the formation of a supersaturated solution, thereby controlling the chlorination of carnallite in the crystallizer. The dissolution rate of potassium and the number of potassium chloride crystal nuclei per unit volume make potassium chloride crystallize with as many large grains as possible and as few small grains as possible

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