Separation technique for boron and magnesium from salt lake brine and preparation of high-purity magnesium oxide

Using salt lake brine with high boron,magnesium and lithium as raw material,the boron was separated from magnesium and lithium with sulfate acid and ion exchange resin,and the magnesium was separated by precipitation with ammonia.The effects of pH value,temperature,time,resin amount,flowing rate of brine and ratio of height to diameter(H/D) of the column on boron removal were investigated under static and dynamic conditions.The optimum process conditions of boron removal are obtained.The results show that the boron removal ratio reaches 95% under the optimum process conditions.The boron concentration of brine has a significant effect on the content of boron in magnesium hydroxide.The content of boron in magnesium hydroxide increases from 0.04 mg/g to 8.82 mg/L with boron increasing from 4.54 mg/L to 1 200 mg/L.Using brine containing 4.54 mg/L boron as raw material to prepare magnesium hydroxide followed by calcination at 1 500 ℃ for 2 h,99.8% magnesium oxide is obtained.