ENHANCED SEPARATION OF PYRITE FROM OXIDIZED COAL BY FROTH FLOTATION USING BIOSURFACE MODIFICATION

Bacterial conditioning prior to froth flotation has been used to enhance the separation of pyrite from naturally oxidized coal. The pyrite surface in the coal slurry was selectively made more hydrophilic by adapted Thiobacillus ferrooxidans bacteria, thereby depressing the floatability of pyrite, but not that of coal. After bioconditioning and removal of the bacterial culture, the coal slurry was subjected to froth flotation at pH 8. The bioconditioning of oxidized coal ahead of flotation improved pyritic sulfur rejection significantly while not greatly affecting coal recovery. The results indicated that biosurface modification is largely unaffected by the state of oxidation of the pyrite and coal, and that the process of bioconditioning followed by flotation works equally well on fresh and oxidized high sulfur coals.