Sulfide Mineral Bioflotation Optimization and Prediction by Mixed Mesophilic Bacteria as a Green Alternative for Chemical Reagents

In recent years, applying biotechnological and environmentally friendly processes as an alternative to hazardous chemical usage such as cyanide in mineral processing has received increasing attention. This paper studied the efficiency of the sulfide minerals’ depression (pyrite, chalcopyrite, sphalerite, and galena) by mixed mesophilic bacteria. After examining the optimal flotation conditions for all four minerals separately by the collector, frother, and activator, the effect of cyanide as one of the most common sulfide minerals depressants in the mineral processing industry was studied. As a result, the highest levels of depression were observed for pyrite and sphalerite, with 76.7% and 75.4% reductions in recovery compared to optimal conditions. The depression efficacy of mixed mesophilic bacteria in single and multi-mineral flotation experiments was studied. In the single-mineral flotation tests, it was observed that in the presence of mesophilic bacteria, pyrite (with a recovery of 21.1%) and galena (with a recovery of 46.3%) were significantly depressed under optimal conditions compared to other minerals. At the same time, chalcopyrite and sphalerite showed a minor change in floatability compared to optimal conditions. An artificial neural network (ANN)-based model was successfully described to predict the system’s performance. Fourier Transform-Infrared Spectroscopy analysis confirmed the high depression level of pyrite by mesophiles. In multi-mineral flotation experiments, effective biodepression of minerals was observed, especially for pyrite. The results demonstrated the high-efficiency biodepression method over hazardous reagent usage such as sodium cyanide for the depression of sulfide minerals. Graphical Abstract