Separating technique for magnesium and lithium from high Mg/Li ratio salt lake brine

Using salt lake brine with high magnesium/lithium ratio as raw material,the process of separating lithium from magnesium in the brine was studied. The technological parameters of the process were obtained. Two precipitation steps were studied in the process using ammonia and ammonium bicarbonate as the precipitator. About 98% of Mg2+ in the brine is precipitated as magnesium hydroxide and the light magnesium carbonate is precipitated respectively. NH4Cl is obtained while the solution is concentrated. And then,the magnesium ion remained in the solution is further extracted out by adding NaOH. The effect of some parameters of the process were studied and the effects of adding method of reagents,concentration of NaOH solution,adding rate of NaOH solution,terminal pH,reactive temperature and reactive time on magnesium extracting rate were investigated. The results show that under the conditions of 10 mol/L NaOH solution,adding rate 0.3-0.5 mL/min,pH 12,temperature 25 ℃,reactive time 20-30 min,Mg2+ is extracted from the salt lake brine completely. The treated solution can be used for preparation for high purity lithium carbonate.