Influence of Inorganic Nitrogen Sources On High Sulfur Coal Bio-Desulfurization: Promoting Pyrite Bioleaching and Surface Effects

Abstract

Exotic microorganisms collected from sewage sludge was used for high sulfur coal biodesulfurization without culture medium addition, and the effect of NO3- and NH4+ on coal biodesulfurization was investigated. The biodesulfurization was significantly inhibited with NO3- addition, but enhanced with the NH4+ addition, the optimal dosage of (NH4)2SO4 is 6 g/L. After biodesulfurization for 30 days, the pyritic sulfur decreased from 2.854% to 0.261%, and the content of nitrogen slightly increased from 0.973% to 1.006%, the NH4+ addition was benefit for biologic removing populate elements. NH4+ could promote bioleaching microorganisms and enhance the indirect bioleaching at the beginning of biodesulfurization. The ammonium jarosite generation might break the pyrite surface and promote the bioleaching at the first 6 days but subsequently decrease the available pyrite surface, which inhibited bioleaching. In addition, during biodesulfurization, the NH4+ was not fully bio-adsorbed by microorganisms and may increase the chemical leaching of pyrite.

Keywords: fat coal, bioleaching microorganisms, biodesulfurization, pyrite, nitrogen sources