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Study on technology of super gravity step separation of rare earth elements in Bayan Obo rare earth ore
- Xi LAN Jintao GAO Zhancheng GUO
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The Chinese Journal of Process Engineering. 2022, 22(10):
1429-1437.
DOI: 10.12034/j.issn.1009-606X.222303
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The rare earth reserves of Bayan Obo mine in China rank first in the world, and its rare earth minerals are mainly light rare earth, of which cerium, lanthanum, praseodymium and neodymium account for more than 97% of the total rare earth oxides, which has important industrial value. Since the rare earth elements have extremely similar physical and chemical properties, it is difficult to realize the separation of different rare earth elements from each other in the current treatment process. In this work, a green and efficient method was proposed for respectively recovering rare earth elements under supergravity from rare earth concentrate. Based on the evolution of mineral phases and elemental migration laws of the rare earth concentrate, it was found that different rare earth phases would be precipitated in different temperature intervals during the melting and cooling precipitation process. It could be concluded that the rare earth elements (REEs: Ce, La, Pr, Nd) were discovered to be precipitated as the rare earth oxide, rare earth ferrate and britholite phases respectively at various temperature ranges of 1400~1500, 1200~1400, and 1100~1200℃, respectively. However, the rare earth phases were intimately intertwined with each other in the normal gravity. Consequently, the respective separation of REEs (Ce, La, Pr, Nd) at their corresponding precipitation temperatures was conducted under the supergravity. 98.38% of Ce was firstly enriched into the rare earth oxide and separated from the concentrate as driven by the supergravity, 97.70% of La was enriched into the rare earth ferrate and separated subsequently, and the Pr and Nd were precipitated further into britholite and separated from the system. Accordingly, the high purity of rare earth oxide, rare earth ferrate, and britholite phases were attained respectively, and the stepwise separation of Ce, La, Pr and Nd in the rare earth concentrate were achieved, achieving the green and efficient recovery of REEs (Ce, La, Pr, Nd) from the Bayan Obo rare earth concentrate with no additives, no hazardous waste, and no secondary pollution.
