Treatment of high-sulfur coal using selective flocculation and microbial desulfurization in a draft-tube slurry bubble column

Abstract

Experiments are performed to study a novel precombustion coal cleaning process for deashing and desulfurization of high-sulfur coals. The process is based on the integration of selective flocculation and microbial desulfurization in a draft-tube slurry bubble column bioreactor (DTSB). In the process, the unique features of the selective flocculation in ash reduction is preserved. Desulfurization of the pyrite particles is subsequently achieved through oxidation of pyrite by Thiobacillus ferrooxidans in a DTSB bioreactor. Samples of Pittsburgh No. 8 seam are used to test this multistage process. In this study, the effect of bacterial adaptation on the oxidation rate of pyrite is examined. Based on the kinetic data, a reactor model for the bio-oxidation rate of pyrite is developed. This model considers the bacterial adhesion and the kinetics of direct and indirect pyrite oxidation by T. ferrooxidans.