Study on selective adsorption of organic depressant on chalcopyrite and pyrite surfaces

Abstract Chalcopyrite and pyrite are difficult to separate under low alkaline environment. The selective depression mechanism of pyrite by sodium dimethyl dithiocarbamate (SDD) was explored in this study. Micro-flotation test showed that when the pH was 8.5, the recovery efficiency of pyrite decreased from 80.18% to 22.17% after adding SDD, while that of chalcopyrite decreased from 96.32% to 92.79%, indicating that SDD has a good selective depression effect on pyrite. Scanning electron microscopy and energy dispersive spectrometry results showed that SDD formed a stable complex on the pyrite surface, while the surface morphology of chalcopyrite did not change. The infrared spectrum study showed that significant SDD characteristic peaks appeared on the pyrite surface, resulting in obvious chemisorption, whereas no SDD characteristic peaks appeared on the chalcopyrite surface. Local electrochemical impedance spectroscopy in-situ study showed that the impedance of the pyrite surface decreased more than that of the chalcopyrite surface after SDD was added, indicating that the adsorption degree of SDD on the pyrite surface was stronger than chalcopyrite. X-ray photoelectron spectroscopy analysis also showed that SDD was significantly adsorbed on the pyrite surface. The above results indicated that SDD could selectively depress pyrite under low alkaline environment, thus increasing the difference in surface hydrophobicity between the two and selectively depressing pyrite.