Chiang Mai Journal of Science

The collectorless flotation contains self-induced flotation and sodium sulfide-induced flotation. In this paper, we studied the electrochemical performance of pentlandite in both circumstance. In moderate oxidation conditions (viz.0mV < Eh < 500mVvs.SHE), pentlandite was oxidized spontaneously with the main oxidation product of S on the surface, and the highest amount of the S on the surface was oxidized to sulfate which resulted in the hydrophilic surface. Sodium sulfide would increase the hydrophobicity of pentlandite by forming more S on the mineral surface. The extra S might come from the oxidation of hydrogen sulfide ions by the ferric ions which dissolved from the mineral during the oxidation process. These results show that the collectorless flotation of pentlandite would be achieved in the presence of sodium sulfide with the Eh of 300-500 mV.