Understanding the effect of grinding media on the adsorption mechanism of cyanide to chalcopyrite surface by ToF–SIMS, XPS, contact angle, zeta potential and flotation

Abstract

As the main copper-bearing sulfide minerals in cyanide tailings, how to improve the flotation recovery of chalcopyrite is of great significance to the comprehensive management of bulk solid waste. To obtain higher leaching rate of precious metals, fine grinding is required. However, the production of numerous interfering ions, accompanied by severe mechanical entrainment, leads to a series of problems in the grinding process. In this context, the correlation between surface adsorption, the occurrence of species on the chalcopyrite surface and the differences in grinding media in cyanidation system would be a key issue for process optimization. Scanning electron microscope–energy dispersive spectrometer (SEM–EDS) and contact angle measurements were performed on the chalcopyrite surface. The results showed that the use of ceramic media avoided excessive surface oxidation caused by the galvanic couple actions between the iron media and chalcopyrite. Zeta potential values revealed that the cyanide adsorbed on the chalcopyrite surface and reacted with positively charged substances, inhibiting the adsorption of collector, which was confirmed by microflotation. Surface chemistry analysis using X–ray photoelectron spectroscopy (XPS) and time–of–flight secondary ion mass spectrometry (ToF–SIMS) confirmed that the chemical environment of the chalcopyrite surface had been changed using the iron media, which accelerated the formation of FeOOH and enhanced the adsorption of CN– on the chalcopyrite surface. It was further demonstrated by ToF-SIMS that the ceramic media exhibited the excellent grinding performance, which excluded the insignificant contribution of impurity elements (mainly Fe). This study provides important surface chemical evidence to gain an in-depth understanding of the effect of grinding environment on the mechanism of cyanide adsorption on the chalcopyrite surface, which plays a crucial role in promoting the possibility of the comprehensive utilization of the cyanide tailings.