Preparation of Anhydrous Magnesium Chloride from Bischofite (MgCl₂·6H₂O) I. Reaction Crystallization of Magnesium Chloride Hexammoniate

Abstract:

Magnesium chloride hexammoniate (MgCl2·6NH3) is an intermediate product for preparation anhydrous magnesium chloride by reaction crystallization method. An experiment study of a semi-batch reaction crystallization is presented. In a single feed operation, magnesium chloride solution is fed to a stirred methanol solution mixed with ammonia to crystallize magnesium chloride hexammoniate. The median crystal size of product increases with increasing stirring rate, reaches a maximum, and then decreases again. Decreasing feed rate or decreasing stirring time increases the crystal size significantly. The reaction temperature and concentration of magnesium ion can also influence the crystal size distribution (CSD). A double feed operation can create larger crystal size than that of single feed operation. The relationship between crystal size and the content of water of the product is discussed.

• Periodical: Materials Science Forum (Volumes 488-489)
• Pages: 57-60
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.488-489.57
• Online since: July 2005
• Authors: Xiang Tian Wang, Jian Hai Zhao, Xing Fu Song, Jin Wang, Jian Guo Yu
• Keywords: Crystal Size Distribution, Magnesium Chloride Hexammoniate, Reaction Crystallization

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[6] 8 10 12 14 16 18 20 22 24 26.

[20] [30] [40] [50] [60] [70] [80] [90] 100 A-Crystal size B-Water Water(%) Median crystal size(¦Ì m) Temperature(¡æ) 0. 2 0. 4 0. 6 0. 8 1. 0 1. 2 BA Fig. 10 Influences of temperature on median crystal size and water content.

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[20] [30] [40] [50] [60] [70] [80] [90] 100 A-Crystal size B-Water Water(%) Median crystal size(¦Ì m) Temperature(¡æ) 0. 2 0. 4 0. 6 0. 8 1. 0 1. 2 BA Fig. 11 Influence of temperature on CV.