Characterization of a complex carbonate-silicate apatite ore and its concentration by a two-stage anionic flotation method

Abstract A carbonate-silicate low weathering phosphate ore from an igneous origin deposit in Southeastern Brazil presents a challenge mainly for apatite flotation from its gangue minerals, calcite and dolomite, plus the presence of phlogopite, diopside, magnetite, richterite, ilmenite, vermiculite, quartz and many other minor impurities. Recently, selectivity has been greatly enhanced by using CO2 instead of air, so in this study a variant process was used. In a first stage, carbonate minerals were floated with the use of CO2 as bubble gas; the collector was a saponified fatty acid, medium hydrocarbon chain. Then, the depressed minerals were floated using a sulfosuccinate collector and air as the froth gas. A significant improvement in the apatite concentration has been achieved: the initial 5.28% P2O5 tenor was raised to 21.58%. The overall P2O5 recovery was 61.8% and 12.0% of the global mass recovery. However, the amount of impurities was still significant with the presence of carbonates, phlogopite and minor magnetite. Therefore, the processing route presented herein is quite viable, but further research is necessary to improve the whole method.