Clean Ion-Exchange Technologies. 2. Recovery of High-Purity Magnesium Compounds from Seawater by an Ion-Exchange Isothermal Supersaturation Technique

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• 作者：Ruslan Kh. Khamizov ; Dmitri Muraviev ; Nikolai A. Tikhonov ; Anna N. Krachak ; Tatyana I. Zhiguleva ; and Olga V. Fokina
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：1998
• 出版时间：June 1998
• 年：1998
• 卷：37
• 期：6
• 页码：2496 - 2501
• 全文大小：71K
• 年卷期：v.37,no.6(June 1998)
• ISSN：1520-5045

文摘

This paper reports the results obtained by studying theion-exchange isothermal supersaturation(IXISS) of magnesium carbonate solutions which is observed duringelution of Mg²⁺ fromcarboxylic resin equilibrated with decalcinated seawater (artificial ornatural) with either 2 MNH₄HCO₃ or with the mixture of 1.5 MNa₂CO₃ and 0.6 M NaHCO₃.Crystallization ofsupersaturated solution in the first case has been shown to lead to theformation of previouslyunknown complex ammonium-magnesium carbonate. The results ofX-ray, chemical, anddifferential thermal analyses have allowed the proposal of thefollowing formula for the newmagnesium compound:(NH₄)₂Mg(CO₃)₂·5H₂O.In the second case, crystallization of magnesiumcarbonate leads to the formation of a pure phase of nesquegonite:MgCO₃·3H₂O of 99.9%purity.Samples of MgO obtained after annealing ammonium-magnesiumprecipitates at 773 K containless than 10^-3% of impurities.