A method for recovering high-purity potassium chloride from fluorination reaction by-products

Abstract

The invention provides a method for recovering highly pure potassium chloride from a fluorination reaction byproduct. The method comprises the following steps: 1, preprocessing: carrying out heat treatment on the fluorination reaction byproduct to remove adhered organic matter wastes; 2, dissolving and separating: placing a preprocessed solid mixture in a separation device, introducing liquid ammonia to dissolve potassium fluoride in the preprocessed solid mixture to form a mixed solution, filtering the mixed solution to obtain a filter cake which is crude primary potassium chloride and a filtrate which is a liquid ammonia solution of potassium chloride, squeezing the filtrate, introducing the squeezed filtrate to a pressure reducing chamber, and reducing the pressure to normal pressure to gasify the liquid ammonia in the filtrate in order to obtain a pure potassium fluoride solid; 3, washing: adding a mixed solvent A to the crude primary potassium chloride, washing the crude primary potassium chloride to remove residual trace impurities, and filtering the washed crude primary potassium chloride to obtain crude secondary potassium chloride; and 4, purifying: adding deionized water to the crude secondary potassium chloride, heating the deionized water to dissolve the crude secondary potassium chloride in order to prepare a saturated solution, cooling the saturated solution to room temperature, adding a solvent B to carry out re-crystallization, filtering the obtained solution, washing obtained crystals with the solvent b, and drying the washed crystals to obtain highly pure potassium chloride.

Description

technical field [0001] The invention relates to a method for recovering by-products in the chemical field, in particular to a method for recovering high-purity potassium chloride from potassium fluoride reaction by-products. technical background [0002] Potassium chloride has a wide range of uses. It is the basic raw material for the manufacture of various potassium salts or alkalis such as potassium hydroxide, potassium sulfate, potassium nitrate, potassium chlorate, potassium red alum, etc. It is also used as a diuretic and a drug for the prevention and treatment of potassium deficiency. use. And potassium chloride accounts for 70%-95% of the by-products of potassium fluoride reaction, which has huge economic value, but has been neglected for a long time, and potassium fluoride is widely used in organic fluorination reactions as a common fluorinating agent. , can also be used for glass carving, food preservation, electroplating, when used as a fluorinating agent in organ...

AI Technical Summary

Problems solved by technology

[0004] ①Patent CN102730710B reacts potassium fluoride with acetonitrile solution of boron trifluoride to make potassium tetrafluoroborate, obtains crude potassium chloride and filters it out; High, there are large cost and environmental protection problems in industrialization

[0005] ② Add appropriate amount of water to the by-product to dissolve most of potassium fluoride and part of potassium chloride, filter out undissolved potassium chloride, add magnesium chloride to the filtrate to obtain magnesium fluoride, filter, apply mechanically to the filtrate, and dry the solid magnesium fluoride. The potassium chloride obtained by the method is easy to introduce magnesium ions, and the content of fluoride ions is also higher, and the product purity is not high

This method cannot recycle potassium fluoride, and the obtained potassium chloride may introduce calcium ion impurities, so that the purity is not high, and the calcium fluoride precipitate has a small particle size and is difficult to filter out by ordinary methods

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