硫酸分解磷矿过程中稀土浸出研究

Study on rare earth leaching in the process of decomposing phosphate rock by sulfuric acid

以贵州织金磷矿石为原料,针对硫酸分解磷矿过程中硫酸钙结晶对稀土浸出影响展开研究,考察了晶种、硫酸化学计量比、磷酸体积分数、Mg^(2+)和Al^(3+)对硫酸钙晶体形貌和稀土浸出率的影响。研究结果表明,晶体平均粒径愈大,长径比愈大,则稀土浸出率愈高。在晶种质量分数为15%,硫酸化学计量比为1.10,磷酸体积分数为20%,温度为75℃,液固比为4∶1,聚乙二醇4 000质量分数为0.2%的工艺条件下,硫酸钙晶体的平均粒径为6.72μm,长径比为5.9,稀土浸出率为55%。

Study was conducted on the effect of calcium sulfate crystallization on the leaching of rare earth during the decomposi- tion process of phosphate rock by sulfuric acid with the phosphate rock in Zhijin, Guizhou as material. The effects of crystal seed, stoichiometry ratio of sulfuric acid, volume fraction of phosphoric acid,Mg^2＋ , Al^3＋ on the morphology of calcium sulfate crystal and the rare earth leaching rate are investigated respectively. The results show that greater the average particle size and the length diame- ter ratios of crystals, higher the rare earth leaching rate. With the concentration of crystal being 15 %, the stoichiometrical ratiol.10, the volume fraction of phosphoric acid 20%, the tempera-ture 75 ℃, the liquid-solid ratio 4 to 1 and the concentration of polyethylene glycol 4 000 at 0. 2 %, the average particle size and the length to diameter ratio of calcium sulfate crystal are 6.72 μm and 5.9, respectively and the rare earth leaching rate is 55%.