LI Hai-lan1,2,3,4, ZHANG Jie3*, WU Lin2,5, ZHANG Yu-song3, HUANG Zhi-long2

(1. College of Resource and Environmental Engineering, Guizhou University, Guiyang 550025, China;
2. State Key Laboratory of Ore Deposit Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550081, China;
3. Mining College, Guizhou University, Guiyang 550025, China;
4. Panzhihua University, Panzhihua 617000, China;
5. Guizhou Provincial Coalfield Geology Bureau, Guiyang 550025, China) 

Abstract: Bauxite usually contains a certain amount of rare earth elements (REE). The production process of alumina leads to the enrichment of almost all REE in the ore into red mud. The content of REE in red mud produced from karst bauxite is relatively high, and is a potential secondary REE resource. The comprehensive utilization of REE in red mud has become one of the research hotspots. Previous studies have shown that the REE is distributed in various mineral phases of red mud, including retained or newly formed mineral phases in bauxite. Isomorphism may be the main occurrence state of REE. Minerals containing Fe or Ti are the main REE carrier minerals. There is only a small amount of REE independent minerals. Silicate or newly formed mineral phases are also the potential REE carrier minerals. At present, the recovery and utilization of REE from red mud are mostly studied in the laboratory research stage, with methods including direct acid leaching, roasting and leaching, and bioleaching. The comparison results show that the direct acid leaching and the roasting and leaching are effective methods for the REE recovery from red mud, but the difficulty is how to increase the selectivity of leaching and to simplify the technological process. In addition, the bioleaching is more environmental friendly and may become the most promising method for recovering REE from red mud in the future. In the recovery process, the multi-element recovery process was designed and developed to extract and recover elements such as Fe, Al, Na, Ti and REE. The future development direction for comprehensive utilization of red mud could include that the residual slag produced by the extraction and recovery of useful metals from red mud will be used as raw materials for the preparation of building decoration materials, catalytic support materials, adsorbents and so on.
 
Keywords: Red mud; rare earth elements; occurrence state; leaching; extraction

ACTA MINERALOGICA SINICA Vol. 41, No.4/5, 2021, page 578