Adsorption of sulfosuccinate collector on apatite and carbonates in a phosphate ore, in the presence of carbon dioxide

A phosphate ore from the Catalao mine (Brazil) poses a challenge for apatite flotation from its carbonate gangue minerals. In recent developments, selectivity has been enhanced by using CO2 instead of air. The adsorption of the sulfosuccinate collector on apatite and carbonates, with air or CO2, was studied through infrared spectrometry (FTIR, transmission mode), X-ray photoelectron spectroscopy (XPS) and zeta potential techniques. The FTIR spectra of apatite and carbonates treated with sulfosuccinate showed the presence of new adsorbed bands on apatite (1725 cm(-1)), consequently the chemical adsorption of the collector, but not on the carbonates. It is believed that this occurs due to the low adsorption density of the collector, which also generates a good selectivity between apatite and the carbonates. The XPS spectra of the apatite surface after conditioning with the collector characterized sulfosuccinate adsorption. The sulphur/carbon (S/C) ratio, however, is well below the value assayed for the pure reagent for absorption in the presence of air, while it matches this figure (S/C = 0.036) when adsorption is performed with CO2 injection. Carbon dioxide thus enhances the collector adsorption on apatite. Successful flotation concentration of apatite with carbonate gangue of the phosphate ore from the Catalao mine is therefore linked to the use of sulfosuccinate as collector, which is highly selective for apatite. The selectivity is enhanced by using CO2 as a gas to generate bubbles.