Enzymatic Biooxidation Technology (EnBiTe): Process Optimization for Recovery of Gold from Refractory Sulfide Ores in Cold Conditions

This study uses modular enzymatic systems to investigate the application of the Enzymatic Biooxidation Technology (EnBiTe) for gold recovery from refractory sulfide ores. The biooxidation process was optimized under various conditions, including substrate flow rates of 5–10 mL/h, circulation flow rates of 50–200 mL/h, and aeration flow rates of 1.0–2.0 L/min. The EnBiTe system utilized two immobilized enzyme modules: a glucose oxidase (GO) module to produce oxidizing agents and a catalase (CAT) module to mitigate oxidative stress by consuming excess hydrogen peroxide. These modules were organized in parallel and series configurations, and within the parallel configuration, they have demonstrated superior performance. Pyrite dissolution reached a maximum of 91% under optimized conditions with a substrate flow rate of 10 mL/h and a circulation flow rate of 100 mL/h. The recovery rate of gold (Au) using cyanidation was higher (90%) in the parallel configuration with a circulation flow rate of 100 mL/h. This research highlights the efficacy of modular EnBiTe systems as controllable and efficient solutions for enhancing gold recovery, offering significant advantages over conventional microorganism-assisted biooxidation methods.