Thermal decomposition of Bayan Obo mixed rare earth concentrate under inert atmosphere
(1. National Engineering Research Center for Rare Earth, GRINM Group Co., Ltd., Beijing 100088, China;
2. School of Metallurgy, Northeastern University, Shenyang 110819, China;
3. General Research Institute for Nonferrous Metals, Beijing 100088, China;
4. GRIREM Advanced Materials Co., Ltd., Beijing 100088, China)
2. School of Metallurgy, Northeastern University, Shenyang 110819, China;
3. General Research Institute for Nonferrous Metals, Beijing 100088, China;
4. GRIREM Advanced Materials Co., Ltd., Beijing 100088, China)
Abstract: To provide basic research for the development and application of advanced technology for the metallurgy of Bayan Obo mixed rare earth concentrate (BOMREC), the thermal decomposition behavior of BOMREC under nitrogen atmosphere was investigated by using the Kissinger method, TGA-DSC and XRD etc., including the thermal decomposition kinetics, phase change, cerium oxidation efficiency, and phase change effect on the leaching efficiency of rare earth elements (REEs). The results indicate that during the roasting at 500-550 °C, the mass loss and activation energy (Ea) are approximately 10% and 148 kJ/mol, respectively. After roasting at 550 °C for 2 h, the bastnaesite in the BOMREC is completely decomposed and converted into rare earth oxides and fluorine oxides. The maximum oxidation efficiency of cerium reaches 0.58%. The maximum leaching efficiency of REEs reaches 49.1% after thermal decomposition at 600 °C for 2 h.
Key words: inert atmosphere; thermal decomposition; cerium oxidation; phase change; Bayan Obo mixed rare earth concentrate