Preparation method of anhydrous magnesium chloride

Abstract

The invention discloses a preparation method of anhydrous magnesium chloride. The preparation method comprises the following steps: S1, mixing bischofite with ammonium chloride to obtain a dehydration raw material; S2, enabling the dehydration raw material to be subjected to primary dehydration at 180-240 DEG C and secondary dehydration at 250-300 DEG C to obtain a crude product of the anhydrous magnesium chloride; S3, heating the crude product of the anhydrous magnesium chloride to a temperature, which is not lower than 250 DEG C, under an protective atmosphere after white smoke around the crude product of the anhydrous magnesium chloride disappears, and performing heat preservation for at least 2h to obtain the anhydrous magnesium chloride, wherein in the steps S2 and the S3, no gas overflows from the reaction system. According to the preparation method disclosed by the invention, the ammonium chloride serves as a protective agent, ammonia gas and hydrogen chloride gas, which are generated after the ammonium chloride is heated and decomposed, are utilized, the hydrogen chloride gas can inhibit hydrolysis reaction, and the ammonia gas can be used for replacing water molecules in hydrated magnesium chloride, so as to further facilitate the obtaining of the anhydrous magnesium chloride. The preparation method has the advantages of simple and easy performing and low cost, and the problem of seriously corroded equipment caused by a pure hydrogen chloride gas method in a high-temperature airtight condition is avoided.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of salt lake resources, and specifically relates to a preparation method of anhydrous magnesium chloride. Background technique [0002] Magnesium and magnesium alloys have many excellent processing and use properties, and the production technology and application research have attracted more and more attention. It is widely used in aerospace, automobile, electronics, communication instruments and other fields, and is known as "green engineering metal structure material in the 21st century". At present, the electrolysis of anhydrous magnesium chloride to prepare magnesium metal is the best process route for the development of the metal magnesium industry, but the raw material preparation of anhydrous magnesium chloride is difficult and the production cost is high, resulting in high cost of the produced magnesium or magnesium alloy, and the product lacks market competitiveness. ...

AI Technical Summary

Problems solved by technology

[0011] (4) Ammonia dehydration of bischofite: MgCl 2 It can react with many organic solvents such as alcohols, ethers, amines, and lipids to form corresponding complexes (such as MgCl with methanol 2 ·6CH 3 OH, and ethanol to generate MgCl 2 ·6C 2 h 5 OH), and react with ammonia to generate MgCl 2 6NH 3 , MgCl 2 4NH 3 , MgCl 2 2NH 3 and other complexes; when heated, these complexes will decompose again, so that anhydrous magnesium chloride can be obtained; this process uses less corrosive ammonia gas as the dehydration medium, avoiding the difficult problem of hydrogen chloride corrosion on equipment, However, the introduction of organic solvents is bound to cause pollution to the environment