Advances in the preparation process and mechanism study of high-purity anhydrous magnesium chloride from magnesium chloride hexahydrate  

作　　者：Hui Ming Xudong Zhang Xinping Huang Lihua Cheng Libo Zhang 

机构地区：[1]State Key Laboratory of Heavy Oil Processing,College of Engineering,China University of Petroleum-Beijing at Karamay,Karamay 834000,China [2]Petrochina Karamay Petrochemical Co.Ltd,Karamay 834000,China [3]Guangdong Provincial Engineering&Technology Center for Corrosion and Safety in Petrochemical Industry,School of Chemical Engineering,Guangdong University of Petrochemical Technology,Maoming 525000,China

出　　处：《Chinese Journal of Chemical Engineering》2025年第2期1-23,共23页中国化学工程学报(英文版)

基　　金：funded by Natural Science Foundation of Xinjiang Uygur Autonomous Region(2022D01F60);Tianshan Talents Plan of Xinjiang Uygur Autonomous Region(2022TSYCJC0001);National Natural Science Foundation of China(22368051);Science and Technology Plan Project of Karamay(20232023hjcxrc0038 and 2024hjcxrc0118);Projects of Talents Recruitment of GDUPT(2023rcyj2005)。

摘　　要：In the extraction of potassium from salt lakes,Mg is abundant in the form of bischofite(MgCl_(2)·6H_(2)O),which is not utilized effectively,resulting in the waste of resources and environmental pressure.Anhydrous MgCl_(2) prepared by the dehydration of bischofite is a high-quality raw material for the production of Mg.However,direct calcination of MgCl_(2)·6H_(2)O in industrial dehydration processes leads to a large amount of hydrolysis.The by-products are harmful to the electrolysis process of Mg,causing problems such as sludge formation,low current efficiency,and corrosion in the electrodes.To obtain high-purity anhydrous MgCl_(2),different advanced dehydration processes have been proposed.In this review,we focus on the recent progress of the dehydration process.Firstly,we discuss the molecular structure of MgCl_(2)·6H_(2)O and explain the reason why much hydrolysis occurs in dehydration.Secondly,we introduce the specific dehydration processes,mainly divided into direct dehydration processes and indirect dehydration processes.The direct dehydration processes are classified into gas protection heating and molecular sieve dehydration process.Indirect dehydration processes are classified into thermal dehydration of ammonium carnallite(NH_(4)Cl·MgCl_(2)·6H_(2)O),thermal dehydration of potassium carnallite(KCl·MgCl_(2)·6H_(2)O),thermal decomposition of the[HAE]Cl·MgCl_(2)·6H_(2)O,organic solvent distillation,ionic liquid dehydration process and ammonia complexation process.In the meanwhile,purity of anhydrous MgCl_(2) of each dehydration process,as well as the advantages and disadvantages,is discussed.The characteristics of different processes with a simple economic budget are also given in this paper.Finally,the main challenges are evaluated with suggested directions in the future,aiming to guide the synthesis of high-purity anhydrous MgCl_(2).

关 键 词：Qinghai salt lake Magnesium chloride hexahydrate Anhydrous magnesium chloride PYROLYSIS HYDROLYSIS Solution 

分 类 号：TQ132.2[化学工程—无机化工]