Bayan Obo REE Tailings Consortium

An acid-producing bacterial consortium engineered to extract rare earth elements (REE) from tailings at the Bayan Obo mine in Inner Mongolia, China, the world's largest rare earth deposit. This functional bacterial consortium achieves exceptional REE recovery rates of 82-83% for the five main light rare earth elements (La, Ce, Pr, Nd, Sm) after 18 days of bioleaching using one-step or two-step processes. The tailings are iron extraction residues from medium-poor oxidized ores containing bastnaesite (REE(CO₃)F) and monazite as primary REE minerals. The consortium employs acid-producing bacteria including actinomycetes (Streptomyces sp.), autotrophic acidophiles (Acidithiobacillus ferrooxidans), and heterotrophic acidophiles (Acidiphilium cryptum) that work synergistically to mobilize REE through acidolysis and organic acid complexation. Key mechanisms include production of organic acids (citric, oxalic, lactic, pyruvic), siderophores, and complexing ligands that solubilize REE from carbonate-fluoride minerals. The two-step process (sequential inoculation with heterotrophs followed by autotrophs) achieves 83.51% recovery versus 82.78% for one-step (simultaneous inoculation), demonstrating synergistic enhancement through pH control and organic acid accumulation. This system represents a critical sustainable biotechnology for recovering strategic REE materials essential for clean energy technologies, permanent magnets, and electronics while remediating millions of tons of existing Bayan Obo tailings.