红土镍矿酸浸沉镍废水制备硫酸镁

以元江红土镍矿硫酸溶出液沉镍废水为原料，加入碱式碳酸镁，在室温下利用不同离子水解pH值差异，实现富镁除杂的目的。实验研究了pH值、反应时间、静置时间对废水中离子浓度的影响，确定了较优操作条件为：pH 值 6.5、搅拌通气时间 5 h、静置时间3 h。在此条件下，废水中镁离子的含量提高7.6%，铁、铝、钙、镍杂质离子的去除率分别为99.85%、99.9%、28.57%、35.8%。将此沉镍废水净化液真空浓缩、结晶，分离干燥得七水硫酸镁产品，其质量达到HG/T 2680—95工业七水硫酸镁合格品的要求。

Preparation of magnesium sulfate from laterite nickel acid leaching wastewater

Increase of magesium ion and removal of impurity ions were achieved through adding basic magnesium carbonate to the laterite nickel acid leaching wastewater and using the difference between hydrolysis pH values of metal ions at ambient temperature. The influence of pH value，reaction time and standing time on the concentration of ions was investigated. The optimal conditions were as follows：pH value 6.5，reaction time 5h，standing time 3h. Under those conditions，the content of magnesium ion increased by 7.6% and the removal rates of iron ion，aluminum ion，calcium ion and nickel ion were 99.85%，99.9%，28.57%，and 35.8%，respectively. Magnesium sulfate heptahydrate was obtained by vacuum concentration，crystallization，separation and drying of purified treated wastewater，the purity of the product was more than 98%，which satisfied the requirement of HG/T 2680—95.