FLOTATION CHARACTERISTICS OF OXIDIZED COAL

The floatability of oxidized coal was investigated by means of electro kinetic studies, contact angle measurements and flotation tests. Elect rokinetic measurements showed that the zeta potential of unoxidized an d oxidized coal samples depends on pH. Hydroxonium and hydroxyl ions a re potentially significant ions, both for oxidized and unoxidized coal . Increasing oxidation times decreased the measured iso-electric point s and increased the negative zeta potential. In the presence of cation ic collectors the negative value of the zeta potential for oxidized co al was changed to a positive value below pH 9.3-10.9 depending on the type and concentration of collector used. Contact angle measurements i ndicated that the natural flotability of unoxidized coal was found to deteriorate on oxidation. Addition of cationic collectors increased th e value of the contact angle of oxidized coal. Flotation tests showed that as the degree of oxidation increases. the floatability of coal de creases. Cationic collectors were found to be effective in the flotati on of oxidized coal.