Advanced Leaching of Cu-Zn, Zn-Pb and Cu-Zn-Pb Tailings using Microwave Heating

This PhD will develop and advance the knowledge on innovative leaching processes to extract valuable (e.g. Cu, Zn, Pb), critical (e.g. In, Ga, Ge) and heavy (e.g. As, Cd) metals from low-grade sulphidic mine tailings. Particularly, the application of microwave (MW) radiation within a whole new research field of metallurgy, namely solvometallurgy, will be studied. An amount of approximately 900 Mt/y of extractive waste, that potentially leads to environmental problems, is produced and stored in tailing ponds in Europe. Sulphidic tailings can contain significant amounts of valuable metals, such as Cu, Zn and Pb. The commonly used metallurgical processes to extract metals from sulphidic ores cannot be applied to low-grade ores, such as tailings, as they are costly and energy consuming. Furthermore, leaching sulphidic tailings with acidic aqueous solutions will suffer from a poor selectivity, giving rise to impossible complicated and expensive downstream processing steps. Hence, this project aims to develop more selective and energy efficient leaching methods to extract valuable metals from sulphidic tailings, namely MW-assisted solvometallurgical leaching. The method will make use of non-aqueous solvents, such as molecular organic solvents, ionic liquids and deep eutectic solvents, combined with microwave technology to increase selectivity and efficiency of metals recovery. This experimental research will study the interactions of MWs and its effects on sulphic tailing materials and solvometallurgical leaching systems. The latter will be developed and studied to gain insights and reach selective metal leaching. It is expected that important advancements in the field can be made, as many possible routes are unexplored and much knowledge is still lacking. In the end, the MW-assisted solvometallurgical process is targeted to obtain >15% energy saving, >15% reagent/solvent saving and >50% shorter leaching time with respect to conventional heated (water based) leaching processes.