氧化钪制备过程中磷酸和磷酸钠组合除锆工艺研究

基于高纯氧化钪制备过程中钪和锆难以分离的问题, 采用磷酸+磷酸钠组合除锆, 研究了钪料液酸度、磷酸加入比例、反应温度、反应时间、陈化时间和磷酸钠添加量对钪、锆沉淀率的影响。结果表明, 最优组合条件为：反应酸度6 mol/L, 磷酸加入量为理论量的1.6倍, 反应温度90 ℃, 反应时间30 min, 陈化时间30 min, 磷酸钠添加量为磷酸的10%。在此条件下, 锆沉淀率达99.85%, 氧化钪损失仅为3.02%。得到的高纯氧化钪产品绝对纯度达99.91%, 相对稀土纯度99.995%。

Zirconium Removal by a Combination of Phosphoric Acid and Sodium Phosphate in the Preparation of Scandium Oxide

Aiming at the difficult separation of zirconium from scandium in the preparation of high-purity scandium oxide, a combination of phosphoric acid and sodium phosphate was adopted to remove zirconium. Effects of acidity of scandium solution, proportion of added phosphoric acid, reaction temperature, reaction time, aging time and dosage of sodium phosphate on precipitation of zirconium and scandium were all examined. An optimal combination was determined as follows: the solution acidity was 6 mol/L, an addition amount of phosphoric acid was 1.6 times of the theoretical amount, reaction temperature was at 90 ℃, reaction time was 30 min, aging time was 30 min, the dosage of sodium phosphate was 10% that of phosphoric acid. It is shown under these conditions, the zirconium precipitation rate reached 99.85%, and the scandium oxide loss rate was only 3.02%. The obtained high-purity scandium oxide has an absolute purity of 99.91% and relative purity of 99.995%.