Heap leaching of ion adsorption rare earth ores and REEs recovery from leachate with lixiviant regeneration

Xiaoyu Meng; Hongbo Zhao; Yu Zhao; Li Shen; Guohua Gu; Guanzhou Qiu

doi:10.1016/j.scitotenv.2023.165417

Heap leaching of ion adsorption rare earth ores and REEs recovery from leachate with lixiviant regeneration

Sci Total Environ. 2023 Nov 10:898:165417. doi: 10.1016/j.scitotenv.2023.165417. Epub 2023 Jul 8.

Authors

Xiaoyu Meng¹, Hongbo Zhao², Yu Zhao¹, Li Shen¹, Guohua Gu³, Guanzhou Qiu¹

Affiliations

¹ School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, China; Key Lab of Biohydrometallurgy of Ministry of Education, Changsha, Hunan, China.
² School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, China; Key Lab of Biohydrometallurgy of Ministry of Education, Changsha, Hunan, China. Electronic address: zhbalexander@csu.edu.cn.
³ School of Minerals Processing and Bioengineering, Central South University, Changsha, Hunan, China; Key Lab of Biohydrometallurgy of Ministry of Education, Changsha, Hunan, China. Electronic address: guguohua@126.com.

PMID: 37429479
DOI: 10.1016/j.scitotenv.2023.165417

Abstract

In this work, semi-industrial scale heap leaching of 200 t ion adsorption rare earth ores (IRE-ore) and rare earth elements (REEs) recovery from lixivium was first conducted. Biosynthetic citrate/(Na)₃Cit, a typical microbial metabolite, was chosen as the lixiviant to conduct heap leaching. Subsequently, an organic precipitation method was proposed, which used oxalic acid to effectively recover REEs and reduce the production cost by lixiviant regeneration. The results showed that the heap leaching efficiency of REEs reached 98 % with a lixiviant concentration of 50 mmol/L and a solid-liquid ratio of 1:2. The lixiviant can be regenerated during the precipitation process, with REE yields and impurity aluminum yields of 94.5 % and 7.4 %, respectively. The residual solution can then be cyclically used as a new lixiviant after simple adjustment. High-quality rare earth concentrates with a rare earth oxide (REO) content of 96 % can be finally obtained after roasting. This work provides an eco-friendly alternative for IRE-ore extraction to solve the environmental issues caused by traditional technology. The results proved feasibility and provided a foundation for in situ (bio)leaching processes in further industrial tests and production.

Keywords: Heap leaching; Ion-adsorption rare earth ore; Noncontact bioleaching; REEs precipitation.