包头稀土矿冶炼分离过程抑制硫酸钙结垢研究

硫酸钙结晶物是一种非常难清理的物质,在包头混合型稀土矿冶炼分离过程中会大量析出,影响设备正常运行和连续化生产。系统研究了P507-煤油-H2SO4萃取体系及P204-煤油-H2SO4萃取体系中硫酸钙结晶行为。分别考察了CaSO4-H2O体系、RE2(SO4)3-CaSO4-H2SO4-H2O体系及MgSO4-CaSO4-H2SO4-H2O体系中温度、稀土浓度、镁浓度与硫酸钙溶解度之间的关系;测定了硫酸钙在真实水浸液(RE2(SO4)3-MgSO4-CaSO4-H2SO4-H2O体系)恒温萃取过程各级水相中的分布情况;在实际生产过程中开展了硫酸钙在不同材质表面的结垢特性研究。综合研究结果,确定了最佳的降钙手段及材料,实现了维持稀土萃取分离过程水相中硫酸钙的浓度低于饱和度及减少其在萃取箱体内结晶的目标。

Study on Calcium Sulfate Scale Prevention in Smelting and Separation Process of Baotou Mixed Rare Earths

Calcium sulfate causes many significant and serious operating and equipment problems in the smelting and separation process of Baotou mixed rare earths for its limited solubility and easy precipitation on the surface of tubes,pumps and equipments.In this research,behaviors of gypsum in the system of P507-sulfonated kerosene-H2SO4 and P204-sulfonated kerosene-H2SO4 were investigated respectively.Parameters such as the temperature,concentration of rare earth(RE)and magnesium sulfate were studied in the different systems of CaSO4-H2O,RE2(SO4)3-CaSO4-H2SO4-H2O and MgSO4-CaSO4-H2SO4-H2O to find out the relationship between them and the solubility of gypsum.Also,solubility of calcium sulfate in the actual leaching solution(system of RE2(SO4)3-MgSO4-CaSO4-H2SO4-H2O)was measured and the distribution of CaSO4 in every stages of constant-temperature extraction procedure was figured out.Further,the property of calcium sulfate scale on the surface of various materials was investigated.Based on the results,both the optimal means and the material for inhibition of calcium sulfate scale were determined.The concentration of calcium sulfate in the water phase of the separation process of rare earth extraction was lower than that of saturation,and the aim of reducing its crystallization in the extraction chamber was finally achieved.