Biodesulfurization of high sulfur fat coal with indigenous and exotic microorganisms

Kaolinite and quartz are the main minerals in fat coal, and pyrite is the main inorganic sulfide in fat coal. After 36 days of biological desulfurization, the total sulfur in fat coal dropped from 5.07% to 277% and 2.75%, and the pyrite removal rates for local and foreign microorganisms were 77.68 and 8788%, respectively. Alien microorganisms oxidize pyrite more effectively than native microorganisms. However, the two microorganisms do not interact with organic sulfur, which exists in fat coal in the form of C-S bonds. FT-IR analysis showed that the structure of kaolinite was damaged, indicating that the potential impact of microorganisms on kaolinite has not been reported before. Raman spectroscopy was used for the first time to study the changes in the structure of coal macromolecules during the bioleaching process. FT-IR and Raman spectroscopy confirmed the change of aromatic C-H and O-H bonds, which led to the increase of carbon crystallinity index.