碳酸盐沉淀法分离硫酸盐溶液中的锰与钙和镁（英文）

Separation of manganese from calcium and magnesium in sulfate solutions via carbonate precipitation

以含14.59g/L Mn^(2+)、1.89g/L Mg^(2+)和1.54g/L Ca^(2+)的硫酸盐溶液为原料,利用碳酸盐沉淀法实现了锰与钙和镁的有效分离。热力学分析与实验结果表明,碳酸盐沉淀体系中锰对镁的选择性明显优于水解沉淀体系,而且加料方式是减少钙、镁共沉淀的主要因素。因而以硫酸锰加入碳酸氢铵的方式,研究碳酸氢铵初始浓度和用量、溶液pH值、反应温度及时间对沉淀过程的影响,并得到最优沉淀条件。结果表明:最优条件下锰、钙和镁离子的沉淀率分别为99.75%、5.62%和1.43%。另外,制得的产品经X射线衍射和能谱扫描电镜分析,结果表明该产品为菱形碳酸锰。

The separation of manganese from sulfate solutions containing 14.59 g/L Mn2+, 1.89 g/L Mg2+ and 1.54 g/L Ca2+ was preformed successfully by carbonate precipitation. The results of thermodynamic analysis and tests indicate that carbonate precipitation holds better selectivity for manganese over magnesium than hydroxide precipitation and the feeding method is the most critical factor for minimizing the co-precipitation of calcium and magnesium. Furthermore, with adding MnSO4 solution to NH4HCO3 solution, the effects of the initial NH4HCO3 concentration, NH4HCO3 amount, solution pH value, reaction temperature and time on carbonate precipitation were evaluated and the optimum precipitation conditions were obtained. Under the optimum conditions, the precipitation rates of Mn2+, Ca2+ and Mg2+ are 99.75%, 5.62% and 1.43%, respectively. Moreover, the prepared manganese carbonate was characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) equipped with energy-dispersive X-ray spectroscopy (EDX). The results demonstrate that the product can be indexed to the rhombohedral structure of MnCO3.