混合稀土碳酸盐晶型沉淀的制备

PREPARATION OF CRYSTALLINE PRECIPITATIONOF MIXED RARE EARTH CARBONATES

以碳酸氢铵为沉淀剂制备了三种混合稀土碳酸盐晶型沉淀。研究了搅拌、［ＮＨ４ＨＣＯ３］／［ＲＥＯ］比、温度、稀土配分、稀土离子浓度和晶种对沉淀过程的影响，发现前四种因素影响程度较大。对于轻稀土型，形成晶型碳酸盐的最佳工艺条件为温度１０～８０℃，［ＮＨ４ＨＣＯ３］／［ＲＥＯ］比３．３～４．０，搅拌０．２５～４．０ｈ；对于中钇富铕型，温度２０～６０℃，［ＮＨ４ＨＣＯ３］／［ＲＥＯ］比３．４～３．６，搅拌１．０～３．０ｈ；对于重稀土型，温度１０～７０℃，［ＮＨ４ＨＣＯ３］／［ＲＥＯ］比３．４～３．８，搅拌０．５～３．０ｈ。轻稀土型和中钇富铕型的晶体结构与镧石型稀土碳酸盐相近，重稀土型则与水菱钇石型稀土碳酸盐相似。

The crystalline precipitation of three kinds of mixed rare earth carbonates were prepared by using ammonium bicarbonate as precipitant. The influence of various parameters, such as stirring, temperature, [NH4HCO3]/ ratio, the distributions of rare earth elements, rare earth ion concentration and seeds were studied systematically. The first four parameters have great effects on the precipitation process. The optimal process conditions for the preparation of crystalline precipitation of rare earth carbonates have been proposed: for light rare earth type, temperature 10～80 ℃, [NH4HCO3]/ 3.4～3.6, stirring time 1～3 h; for heavy rare earth type, temperature 10～70 ℃, [NH4HCO3]/ 3.4～3.8, stirring time 0.5～3 h. The crystal structures of light rare earth type and mediumyttrium and richeuropium type rare earth carbonates are similar to that of lanthanite, the crystal structure of heavy rare earth type is similar to that of tengerite.