Simultaneously leaching of copper and manganese from low-grade ore from Boleo Mine by bacterial sulfur oxidation

The increasing global demand for Mn necessitates cost-effective recovery methods applicable to low- and medium-grade ores. Reductive bioleaching has emerged as a promising technique for Mn extraction from low-grade ores. This study aimed to simultaneously bioleach both Cu and Mn from low-grade ore obtained from Boleo, Mexico, using Acidithiobacillus thiooxidans. Additionally, the influence of activated coffee charcoal on the leaching process was examined. The biotic samples exhibited significantly higher Cu (70.6–71.9%) and Mn (78.8–82.2%) extraction compared to abiotic samples (41.7% Cu and 2.7% Mn). The presence of activated coffee charcoal improves the extraction rate and leaching efficiency of Mn, but it does not significantly impact Cu bioleaching from low-grade ore. Additional experiments confirmed that sulfur oxidation by A. thiooxidans played a significant role in Mn dissolution. A. thiooxidans oxidizes elemental sulfur, and during this process, Mn undergoes reduction either through enzymatic or non-enzymatic pathways. After the bioleaching process, the majority of Cu and Mn in the aqueous phase, and Cu and Mn within the residual ore can also be easily leached in a weak acid environment. This study demonstrates the applicability of simultaneous bioleaching without the necessity of an additional chemically reducing agent, effectively contributing to metal extraction practices. Further optimization of operational parameters, including sulfur concentration and operation time, is necessary to enhance leaching efficiency before the scaling-up of the approach validated in the presented study.