Recovery of Macroelements

Country Mg produced (million tons) Number of plants 

Ion-Exchange and Sorption Methods for Recovering Magnesium from Seawater 

Traditional methods for producing magnesium by processing hydromineral sources fail to satisfy the newer ecological standards. Consequently, new, alternative technologies, based on sorption methods are being considered despite the profitability of earlier methods. 

This approach has several drawbacks. The extractant gradually contaminates the ion-exchange resin and gradually permeates the seawater. The ion-exchange capacity of the resin is used ineffectively, because of the relatively low selectivity of Dowex 50 cation exchangers for Mg relative to Na in the presence of seawater. The equilibrium capacity of Dowex 50x8 toward Mg by sorption fix m seawater does not exceed 1 mg-equiv/cm of the resin bed. 

In recent years, a number of processes have been developed [35-37] for the ion exchainge recovery of Mg from seawater by applying weak-acid (carboxylic) ion exchangers. The following monofunctional carboxylic acid cation exchangers (methylmethacrylate-DVB type) were 

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