Flotation separation of carbonate from sulfide minerals, I: flotation of single minerals and mineral mixtures

Removal of carbonate gangue is desirable prior to acid pressure leaching when a refractory gold-bearing sulfide ore contains a significant amount of carbonate minerals. This is usually achieved by direct flotation of the gold and sulfide minerals into a bulk flotation concentrate. However, if the flotation recoveries of gold and sulfide are unsatisfactory, reverse flotation of the carbonate minerals is a possible alternative. In this study, calcite and dolomite were used as representative carbonate minerals, and pyrite and chalcopyrite as representative sulfide minerals to study the feasibility of the reverse flotation. It was found that by using sodium oleate as a collector, and a mixture of thioglycollic acid and citric acid as a selective depressant, calcite could be selectively floated away from the sulfide minerals between pH 9 and 11. Dolomite could be separated from pyrite but could not be separated from chalcopyrite under the reported test conditions.