Composite lixiviant synergy for ionic rare earth extraction: Dual-perspective mechanistic insights from metabolomics and mineralogical characterization

Abstract

Rare earth elements are scarce materials that are crucial in new technology industries; however, realizing their efficient and environmentally friendly mining and utilization is challenging. In this study, response surface methodology was employed to optimize a fermentation medium of Bacillus thuringiensis (W-50) and its fermentation broth, which were compounded with magnesium acetate to create a composite lixiviant. The composite lixiviant, formulated after media optimization, was found to significantly enhance the leaching efficiency. Untargeted metabolomics was employed to analyze the changes in metabolites before and after leaching, and various characterization techniques were used to examine the changes in the ore after leaching. The results showed that a rare earth leaching rate of 98.6 % could be achieved when the initial concentration of C₄H₆O₄Mg in the composite lixiviant was 0.2 mol/L, the initial pH was 4, and the leaching solid–liquid ratio was 1:3. The metabolomics results indicated that organic acids and their derivatives played important roles in the leaching process. This research provides a useful reference for the development of a composite lixiviant for ionic rare earth ores and provides a framework for advancing environmental protection and operational efficiency in the rare earth mining industry.