Production of boric acid from colemanite wastes by bioleaching tailings

In this study, the methods of bioleaching and chemical leaching were applied to recover boric acid from colemanite tailings. The samples, taken from Etibor A.Ş. Emet, Kütahya and Aspergillus niger produced from Biology department, Faculty of Literature and Science, University of Çukurova, were used in the bioleaching experiments. The pH in various solid rates, potential changing (mV), heat, organic acid concentration (oxalic and citric acid) and B2O3% on the process of bioleaching were measured during the experimental work. Chemical leaching using oxalic acid with Anova-Yates experimental test technique was also studied with respect to the effects on the solids rates, oxalic acid concentration, heat and B2O3% extraction yield. Solubility of B2O3% increased with decreasing of pH but it decreased with increasing of solids rate for bioleaching experiments. The highest extraction values of B2O3% were determined as 97.31% at 3% solids rates, pH 3.98, mV 180.8 and 32 oC for bioleaching and as 64.08% at 5% solids, 20 g/L acid concentration and 30 oC for chemical leaching. Key words: Bioleaching, Chemical leaching, Aspergillus niger, Colemanite