Behavior of sulfate in preparation of single light rare earth carbonate by Mg(HCO3)2 precipitation method★

• 作者: Meng Wang Xiaowei Huang Zongyu Feng Chao Xia Deliang Meng Zonghe Yu
• 来源期刊: 稀土学报（英文版）
• 年，卷（期）: 2021,（7）
• 所属期刊栏目: CHEMISTRY AND HYDROMETALLURGY
• 页码范围: 850-857
• 页数: 8页
• 语种: 英文

摘要

The precipitation of the water-leaching solution of Baotou mixed rare earth (RE) concentrate roasted with sulfuric acid using ammonium bicarbonate for producing RE carbonate produces a mass of ammonia-nitrogen wastewater because of the relatively low solubility of rare earth sulfate. To solve the serious problem of ammonia-nitrogen pollution, new precipitators need to be developed urgently so as to meet the requirements of environmental protection and impurities content of the product (SO42-<1.8 wt％in RE carbonates products). In this paper, we studied the effects of feeding modes on the behavior of SO42- during the preparation of light RE carbonate (RE = La, Ce, Pr, Nd) from their sulfate solutions using Mg(HCO3)2 as a precipitant. The results indicate that the contents of SO42-in the La and Ce precipitates using positive feeding mode exceed 16 wt％ because of the formation of La2(CO3)2.15(-SO4)0.85?4H2O and Ce2(CO3)2.15(SO4)0.85?3H2O, while those of the Pr and Nd precipitates are 4 wt％-5 wt％since they exist in the form of n-carbonate. The precipitates prepared using synchronous feeding mode are all RE carbonate with only 4 wt％-5 wt％of SO42-enclosed in the precipitation. The content of SO42-in the RE carbonate obtained using reverse feeding mode is the lowest. Among them, the content of SO42-in La precipitate is only 1.40 wt％. Both synchronous and reverse feeding modes can effectively reduce the content of SO42- in RE carbonate, which provides theoretical guidance for the preparation of qualified light RE carbonate products by Mg(HCO3)2 precipitation method.