Leaching of Ion Adsorption Rare Earths and the Role of Bioleaching in the Process: A Review

Ion adsorption rare earths resource has gained significance as a crucial worldwide strategic metal resource because of its high concentration of heavy rare earth elements. Mining technology is continuously undergoing development and improvement in order to facilitate the extraction of rare earth elements more efficiently. The utilization of leaching agents like ammonium/magnesium/aluminum sulfate has significantly enhanced the production efficiency of rare earth elements compared to sodium chloride (barrel/pool leaching). New technologies, while beneficial, have the potential to increase land/water contamination and landslides through heap/in-situ leaching technologies. Therefore, researchers remain dedicated to the investigation and advancement of novel leaching agents that are devoid of ammonia, possess reduced ammonia content, or are organic in nature. This paper presents an in-depth examination of the mining technology for ion adsorption rare earths, with the goal of promoting its efficient and clean development. The composition of rare earth ore at different vertical depths, the evolution of mining technology in recent decades, and the inadequacies of existing technologies are reviewed. Critical remarks are being made regarding the ongoing research on novel mining technology for extracting ion adsorption rare earths. The leaching characteristics are discussed from the viewpoints of wettability, diffusive double electric layer theory, plate theory, and quantum mechanics. In the later half of the paper, bioleaching technologies with application possibility are discussed in detail. The content covers the basic features of the microorganisms used, the bioleaching mechanism, leaching characteristics, and strengthening measures. We hope that the work will be useful to other scholars and will help to advance technical progress.