Clean production technology of selective decomposition of Bayan Obo rare earth concentrate by NaOH

With the deepening understanding of the concept of sustainable development in the world, the roasting method of concentrated sulphuric acid with high pollution and energy consumption adopted by Bayan Obo rare earth ore has become a technical bottleneck and pollution source that seriously restricts the development of rare earth production enterprises. This paper proposes a new clean smelting technology for Bayan Obo rare earth ore, which mainly includes oxidative roasting, NaOH roasting, water washing and acid dissolution. The experimental results show that under the optimum experimental conditions, the washing rate of F and P can reach 63.21% and 17.24%, and the extraction of rare earth can reach 88%. Compared with the existing technology, the new smelting technology has greatly reduced the pollution of three wastes, which can not only realize the recovery of P and F, but also fundamentally alleviate the damage of P and F to the subsequent extraction process. Moreover, the amount of NaOH is less and Th resources are relatively concentrated. Both of them can be recovered economically and reasonably. The new smelting technology has the advantages of short process flow, simple operation and predictable environmental protection. (C) 2019 Elsevier Ltd. All rights reserved.