Study on Preparing Magnesium Hydroxide with Rare Earth Extraction Separation Wastewater

Wastewater containing magnesium chloride(MgCl2),generated from the rare earth solvent extraction separation process,together with the dolomite as the raw materials,were used to produce magnesium hydroxide(Mg(OH) 2).To solve the filtration difficulty of Mg(OH) 2,the effects of temperature,feeding mode,feeding rate,seed concentration,sulfate concentration and direct reaction on the sedimentation and filtration performance of the as-prepared Mg(OH) 2 slurry were investigated.Results showed that rapid subsidence and filtration of Mg(OH) 2 could be achieved by directly adding light-burned dolomite powder into the MgCl2 wastewater,and the quality of the as-prepared Mg(OH) 2 accorded with the industry standard.XRD and SEM were used to characterize the product.The MgCl2 wastewater and dolomite resources could be utilized comprehensively with this process.