Sulfonated brown coal: A novel depressant for the selective flotation of scheelite from calcite

Abstract In the present study, the feasibility of sulfonated brown coal, a hydrophilic macromolecular mixture, to be applied as a depressant in the flotation separation of scheelite and calcite was delved into by micro-flotation experiments. Besides, its depression mechanism was studied by Zeta potential measurement, FTIR spectra and contact angle measurement. As suggested from the results of pure mineral and binary mixed minerals flotation tests, scheelite and calcite could be effectively separated in the case of slurry pH of 6 ∼ 12, sulfonated brown coal dosage of 7 mg/L and sodium oleate dosage of 50 mg/L. Sulfonated brown coal showed high effectiveness in selectively inhibiting calcite. As revealed from the results of Zeta potential measurement, FTIR spectra and contact angle measurement, the adsorbing effect of sulfonated brown coal on the calcite surface was larger than on the scheelite. When sulfonated brown coal was being adsorbed, the sodium oleate adsorbing process was decelerated in calcite; as a result, the hydrophilicity and the floatability of calcite were enhanced and deteriorated, respectively. However, sulfonated brown coal was basically not adsorbed on the scheelite surface, which slightly restricted the adsorption of sodium oleate on scheelite surface. Sulfonated brown coal could act as an alternative depressant for separating scheelite and calcite flotation.