Effect and mechanism of organic depressant on the hydrophobicity of chalcopyrite and pyrite under weakly alkaline environment

In a chalcopyrite and pyrite flotation system, the effect and mechanism of organic depressant sodium dimethyl dithiocarbamate on the hydrophobicity of chalcopyrite and pyrite were studied. The micro-flotation test results revealed that the pyrite recovery efficiency decreased from 80.31% to 23.68% under weakly alkaline environment (pH 8.5) after adding SDD. The zeta potential results indicate that the potential on the pyrite surface decreased after the SDD was added. The coordination group –CSS– in SDD can trap cations and generate hydrophilic dithiocarbamate on the pyrite surface. The results of the scanning electron microscopy and energy dispersive spectrometry show that after the addition of SDD, complexes were formed on the surfaces of the pyrite, while the surface morphology of the chalcopyrite hardly changed. The X-ray photoelectron spectroscopy results showed that the SDD was adsorbed on the pyrite surface and reduced the hydrophobicity of the pyrite. The Time-of-flight secondary ion mass spectrometry analysis results revealed that the normalized peak value (0.001) of CSN− on the chalcopyrite surface was considerably lower than that on the pyrite surface (0.0113) after the addition of SDD. All these results have established that SDD influenced the hydrophobicity of pyrite and had little influence on chalcopyrite hydrophobicity.