Role of micro-organisms in the leaching of critical metals from tungsten mine wastes: from the microscale to the field scale

International audienceThe availability of primary resources will continue to be a growing need to satisfy the increasing global demand for raw materials, with the consequence of the production of waste products from exploration and mining activities. An innovative approach is to consider tailings/wastes from mining in a circular economy concept, as secondary raw materials. The REVIVING project has been developed in this context, with coupled fundamental and applied approaches, with the objective of obtaining optimized experimental models for efficient recycling of critical metals from mining wastes, based on the manipulation of the indigenous tailing’s microbiome.We tested different leaching processes of metals of interest (Cu, Mn, Mg, Zn, W and Mo) from the mining waste of Panasqueira (Portugal). A first series of batch experiments was carried out with four bacteria isolated from this waste at increasing cell concentrations (107, 108 and 109 cells/ml) and under variable physiological conditions (live, dead, with nutrients...). Another batch reactor is also currently applied to evaluate the acidophilic leaching process via ferrooxidizing and sulfo-oxidizing micro-organisms enriched from the Panasqueira mine waste. Results from column reactors showed a limitation of the mobility of bacterial cells in the reactor due to the very small waste grain size leading to a strong filtration of the cells. The optimization of the cell transfer process is underway with a system dynamics approach in columns with different filling materials (waste, residues...) and experimental conditions (flow, saturation, geochemistry, microbiology...).The continuous monitoring of physico-chemical parameters (pH, O2, salinity and concentrations of metals and major ions...) and biological parameters (cell density by cytometry, qPCR and diversity by DNA-metabarcoding) will allow the identification of the dominant processes for a better understanding of the bioleaching phenomenon and therefore to design an efficient system for recycling metals from mining waste on a large scale

Role of micro-organisms in the leaching of critical metals from tungsten mine wastes: from the microscale to the field scale

International audienceThe availability of primary resources will continue to be a growing need to satisfy the increasing global demand for raw materials, with the consequence of the production of waste products from exploration and mining activities. An innovative approach is to consider tailings/wastes from mining in a circular economy concept, as secondary raw materials. The REVIVING project has been developed in this context, with coupled fundamental and applied approaches, with the objective of obtaining optimized experimental models for efficient recycling of critical metals from mining wastes, based on the manipulation of the indigenous tailing’s microbiome.We tested different leaching processes of metals of interest (Cu, Mn, Mg, Zn, W and Mo) from the mining waste of Panasqueira (Portugal). A first series of batch experiments was carried out with four bacteria isolated from this waste at increasing cell concentrations (107, 108 and 109 cells/ml) and under variable physiological conditions (live, dead, with nutrients...). Another batch reactor is also currently applied to evaluate the acidophilic leaching process via ferrooxidizing and sulfo-oxidizing micro-organisms enriched from the Panasqueira mine waste. Results from column reactors showed a limitation of the mobility of bacterial cells in the reactor due to the very small waste grain size leading to a strong filtration of the cells. The optimization of the cell transfer process is underway with a system dynamics approach in columns with different filling materials (waste, residues...) and experimental conditions (flow, saturation, geochemistry, microbiology...).The continuous monitoring of physico-chemical parameters (pH, O2, salinity and concentrations of metals and major ions...) and biological parameters (cell density by cytometry, qPCR and diversity by DNA-metabarcoding) will allow the identification of the dominant processes for a better understanding of the bioleaching phenomenon and therefore to design an efficient system for recycling metals from mining waste on a large scale