Separation of metal ions and resource utilization of magnesium from saline lake brine by membrane electrolysis

摘要

The extraction of potassium or lithium from saline lake generates the discharge of waste liquid and residue containing magnesium, which occupies many land and even covers the mineral deposit. Long-term accumulation of residuals with high magnesium content may also pollute groundwater. Therefore, the comprehensive utilization of saline lake resources must be realized, especially magnesium. In this work, a novel cation exchange membrane (CEM) electrolysis method of separating cations from brine and utilization of magnesium was raised. What's more, the concentrations of electrolyte were optimized in electrolysis of magnesium chloride process. It also provides data for cations separation of simulating saline lake brine by electrolysis. In this paper, the effects of electrolyte concentrations on cell voltage, catholyte pH and current efficiency in the electrolysis process were investigated. The phase, morphology and particle size distribution of magnesium hydroxide were also characterized. Magnesium extraction rate can reach 90.62% in the process of simulating brine electrolysis. The separation rate of metal cations reached 91.02% and the consumption rate of chlorine in anodic brine reached 97.59%. The electrolytic catholyte containing almost no Mg2+ can be directly used to prepare lithium carbonate. The anolyte desalted magnesium and chloride can be used to extract boron.