Investigation of the removal of impurities from industrial raw materials by bioleaching

In this study, bioleaching and chemical leaching methods were used for kaolin, feldspar and quartz sand. Bacteria as Acidithiobacillus ferrooxidans, Acidithiobacillus thioooxidans and fungus as Aspergillus niger, used in bioleaching, obtained from Deutsche Sammlung von Mikroorganismen und Zellkulturen (DSMZ). The effects of solids rate, bacterium density and particle size were investigated on the bioleaching experiments using bacteria. The effect of only solids ratio was investigated on the bioleaching experiments using fungus. For each parameter applied, pH, temperature, bacteria quantity and Fe content in the solution were measured. Using Yates-ANOVA experimental test technique, the effects of solids ratio, temperature and oxalic acids ratio were investigated on the chemical leaching experiments. Aspergillus niger was determined as an effective fungus in bioleaching experiments. Furthermore, solids ratio increased with decreasing dissolution ratios of Fe, increase of bacteria quantity resulted in increasing dissolution rates of Fe on the bioleaching experiments. Solids ratio and temperature were effective parameters on the chemical leaching. The removal of Fe2O3 was determined as: 77.13% for kaolen, 60.05% for feldspar and 44.70% for quartz sand for bioleaching experiments with Aspergillus niger. 94.89% for kaolen, 67.23% for feldspar and 97.02% for quartz sand for chemical leaching experiments. Finally, bioleaching experiment results were evaluated as kinetic. Values of k and R2 were determined as 0.0675 day-1, 0.91 for kaolin; 0.0375 day-1, 0.85 for feldspar and 0.0240 day-1, 0.90 for quartz sand.