Effect of the hydration film on the surface sulfidization of different oxide ores: A DFT study

Abstract

Sulfidization is a commonly used pretreatment process to improve the flotation of oxide ores. However, not all oxide minerals can be sulfidized. The huge sulfidization differences between smithsonite and quartz are a typical example. In this paper, DFT calculations were used to simulate the sulfidization of different oxide ores with smithsonite and quartz as an example. The calculation results showed that the hydration film plays a decisive role in whether the oxide ore can be sulfidized or not. For the smithsonite, HS can break the barrier of its surface hydration film and it can be sulfidized. However, for the quartz, due to the powerful obstacle of its surface hydration film to HS, its sulfidization failed. To find out the internal mechanism, the overlap population, PDOS, and electronic configurations were further analyzed, and their relationship with sulfidization behaviors was established. The analysis results demonstrated that Zn-O bond was more vulnerable than Zn-S bond while Si-O was much more intense than Si-S bond. Moreover, a mechanism model was also proposed to elucidate the different impacts of hydration film on the sulfidization of these two representative minerals. This work is helpful to enhance the understanding of different oxide ore sulfidization.