Red Mud (RM) is a byproduct of the Bayer Process, used to extract alumina from bauxite. This residue contains valuable metals and rare earth elements (REEs), which can be bioleached under acidic conditions and later recovered, eventually reducing the RM pollution potential. The focus of this study was to extract metals through bioleaching using biostimulated biomass. A sequencing batch reactor (SBR) was operated at two different solid to liquid ratios (S/L, 2% and 1.5%) under aerobic conditions, using a feeding strategy based on pH evolution over time. The lowest pH obtained at 2% S/L was 3.8. Metals extraction efficiencies were 68 ± 18% for Mn, 58 ± 4.5% for Mg, 51 ± 2.9% for Al, 0.6 ± 0.07% for Ti and < 0.1% for Fe. At 1.5% S/L, a slightly lower pH was achieved (3.4), with metals extraction efficiencies similar to those obtained at 2% S/L, but more stable over time. At 1.5% S/L, REEs (i.e., Nd, Ce, Y, Sc and La) extraction efficiencies were also evaluated, and the highest value was obtained for Nd (around 65%). The results were promising and provided useful information for further enhancing the efficiency of metals extraction, in the perspective of process scale-up.

赤泥 (RM) 是拜耳法的副产品，用于从铝土矿中提取氧化铝。这些残留物含有有价值的金属和稀土元素 (REE)，可以在酸性条件下进行生物浸出并随后回收，最终减少 RM 污染的可能性。这项研究的重点是使用生物刺激的生物质通过生物浸出来提取金属。序批式反应器 (SBR) 在有氧条件下以两种不同的固液比（S/L、2% 和 1.5%）运行，使用基于 pH 值随时间变化的补料策略。2% S/L 时获得的最低 pH 值为 3.8。金属萃取效率为 Mn 68 ± 18%、Mg 58 ± 4.5%、Al 51 ± 2.9%、Ti 0.6 ± 0.07% 和 Fe < 0.1%。在 1.5% S/L 下，实现了略低的 pH 值 (3.4)，金属萃取效率与 2% S/L 下获得的相似，但随着时间的推移更加稳定。在 1.5% S/L 下，还评估了 REE（即 Nd、Ce、Y、Sc 和 La）提取效率，并且 Nd 获得了最高值（约 65%）。从工艺规模扩大的角度来看，结果很有希望，并为进一步提高金属提取效率提供了有用的信息。