Dissolution of mining waste and semi-selective solubilization of magnesium by "Fervidacidithiobacillus caldus".

Aim: Several raw materials are identified as critical to securing non-energy supplies for industrial value chains. Magnesium (Mg) is central to the global drive toward electrification and, as such, is both economically important and under high supply risk. This project evaluated a biologically mediated strategy to solubilize Mg-containing waste in the pursuit of valorizing waste streams and to inform on strategies for the winning of metals from the solubilized waste.

Methods And Results: The acidophilic bacterium "Fervidacidithiobacillus caldus" more efficiently produced sulfuric acid from biologically generated "biosulfur" than elemental sulfur and this effect was attributed to its reduced particle size and general miscibility. Biogenic sulfuric acid effectively solubilized the waste, the bulk of which was oxides and carbonates of Mg and calcium. In shake flask systems, >74% of Mg was solubilized within 5 minutes of waste addition to the culture and almost 99% of Mg was solubilized by day 57. Increased loading of non-acid labile wastes over time and increasing solubilized Mg, calcium, iron, and manganese did not appear to affect the acid generation potential of "Fervidacidithiobacillus caldu."