A process is disclosed for purifying a composition comprising at least one rare-earth element. The process is useful for removing radioactive impurities from these elements. The process comprises the steps of: (1) forming an aqueous solution of the composition to be purified having a pH between 4.0 and 6.5; (2) precipitating a portion of the rare earth and the radioactive impurities by adding to the solution, while maintaining the pH between 4.0 and 6.5; (i) a soluble barium or strontium salt; (ii) a soluble aluminum, magnesium or zirconium salt; (iii) a selective precipitating agent; and (iv) a sulfate ion-providing salt. The preferred selective precipitating agent is 8-hydroxyquinoline. After precipitation, the process is completed by the steps of: (3) separating the solution from the precipitate and (4) recovering purified rare earth from the solution. The process produces highly purified rare earth which can be used to form phosphors for X-ray screens.
本发明公开了一种用于纯化至少一种稀土元素组成的组合物的方法。该方法有助于从这些元素中去除放射性杂质。该方法包括以下步骤:(1)形成一个pH在4.0到6.5之间的待纯化组合物的
水溶液;(2)通过向溶液中加入可溶性的
钡盐或
锶盐、可溶性的铝盐、
镁盐或
锆盐、选择性沉淀剂和
硫酸盐提供离子的盐,在保持pH在4.0到6.5之间的条件下,沉淀出部分稀土和放射性杂质。首选的选择性沉淀剂是
8-羟基喹啉。沉淀后,该方法通过以下步骤完成:(3)将溶液与沉淀物分离;(4)从溶液中回收纯化的稀土。该方法生产高度纯化的稀土,可用于制造X射线屏幕的荧光体。