Iron mine tailings often contain valuable minerals such as apatite, which is attractive as a secondary source of phosphorus to alleviate the ongoing depletion of high-grade accessible phosphate rock reserves used in the fertilizer industry. This study combines an initial flotation stage to concentrate apatite from iron mine tailings with a bioleaching stage to solubilize phosphate from the concentrate using sulfuric acid generated from the oxidation of elemental sulfur by Acidithiobacillus (At.) thiooxidans. It was found that the flotation process concentrates hydroxylapatite from the original iron mine tailings with a high grade (~ 73 wt%) and a particle size between 70 and 80 μm. The solubilization of phosphate from the recovered apatite concentrate was greatly enhanced by generating biogenic sulfuric acid, extracting ~ 59 and 55% of phosphate for the bioleaching experiments conducted with initial pH values of 2.0 and 2.5, respectively. The formation of phosphogypsum under acidic conditions in the bioleaching experiments might limit the extent of solubilization of the concentrate, as elemental sulfur was detected by X-ray diffraction in the bioleached solid residue, which remains available as an energy and electron source for the bacteria. This work demonstrates the feasibility of recycling an important residue from mining operations to recover a critical raw material, providing economic, environmental, and strategic benefits. © 2025 Elsevier B.V., All rights reserved.