Bayan Obo mixed rare earth (RE) concentrate is one of the most significant rare earth mineral resources worldwide. However, the concentrated sulfuric acid roasting method, which is commonly used to treat ores, generates pollutants such as waste gas, wastewater, and leach residue, resulting in the squandering of the associated resources. This paper introduces a green process involving selective mineral phase transformation (MPT) by heating, followed by leaching to separate bastnaesite and monazite in a mixed RE concentrate to facilitate their subsequent decomposition or extraction. The effects of the MPT conditions on rare earth extraction were investigated. During the MPT process, bastnasite decomposed into REOF, which is more easily leached, whereas monazite remained unchanged. Under suitable conditions, the leaching efficiency of REOF reached 93.7%, while that of monazite (REPO) was only 3.2%. Furthermore, the content of monazite in the leach residue was 91.2%. Compared to the mixed RE concentrate, numerous cracks and pores were generated on the surface and inside the MPT products. Furthermore, the total pore volume and specific surface area significantly increased, which made the reaction between the MPT products and hydrochloric acid more efficient. Thus, the MPT process facilitated the leaching of bastnasite and its separation from monazite.

中文翻译：

---

通过氮气加热和 HCl/AlCl3 浸出，高效分离混合稀土精矿中的氟碳铈矿 (REFCO3) 和独居石 (REPO4)


白云鄂博混合稀土（RE）精矿是全球最重要的稀土矿产资源之一。然而，常用的浓硫酸焙烧法处理矿石，会产生废气、废水、浸渣等污染物，造成资源浪费。本文介绍了一种绿色工艺，包括通过加热进行选择性矿物相变（MPT），然后浸出以分离混合稀土精矿中的氟碳铈矿和独居石，以便于随后的分解或提取。研究了 MPT 条件对稀土萃取的影响。在MPT过程中，氟碳铈矿分解成REOF，更容易浸出，而独居石则保持不变。在适宜的条件下，REOF的浸出效率达到93.7%，而独居石（REPO）的浸出效率仅为3.2%。此外，浸出渣中独居石的含量为91.2%。与混合稀土精矿相比，MPT产品的表面和内部产生了大量的裂纹和孔隙。此外，总孔体积和比表面积显着增加，这使得MPT产物与盐酸之间的反应更加有效。因此，MPT 工艺促进了氟碳铈矿的浸出及其与独居石的分离。