Improved Understanding of the Sulfidization Mechanism in Amine Flotation of Smithsonite: An XPS, AFM and UV–Vis DRS Study

Abstract

Sulfidization is required in the amine flotation of smithsonite; however, the sulfidization mechanism of smithsonite is still not fully understood. In this work, X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and UV–vis diffuse reflectance spectroscopy (UV–vis DRS) were used to characterize sulfidized and unsulfidized smithsonite. The XPS and UV–vis DRS analyses showed that smithsonite sulfidization is a transformation of ZnCO3 to ZnS on the smithsonite surfaces. However, this transformation is localized, resulting in the coexistence of ZnCO3 and ZnS or in the formation of ZnS island structures on the sulfidized smithsonite surfaces. AFM height imaging showed that sulfidization can substantially change the surface morphology of smithsonite; in addition, AFM phase imaging demonstrated that sulfidization occurs locally on the smithsonite surfaces. Based on our findings, it can be concluded that smithsonite sulfidization is clearly a heterogeneous solid–liquid reaction in which the solid product attaches at the surfaces of unreacted smithsonite. Smithsonite sulfidization involves heterogeneous nucleation and growth of ZnS nuclei. Moreover, the ZnS might nucleate and grow preferentially in the regions with high reactivity, which might account for the formation of ZnS island structures. In addition, sphalerite-structured ZnS is more likely to be the sulfidization product of smithsonite under flotation-relevantconditions, as also demonstrated by the results of our UV–vis DRS analyses. The results of this study can provide deeper insights into the sulfidization mechanism of smithsonite.

Controlled dispersion of ZnO nanoparticles produced by basic precipitation in solvothermal processes

“…In the spectrum obtained from synthesis III, in the wavelength region of 200-360 nm, a different absorption profile can be observed compare to another two spectra. Since carbonate anion has absorption at this wavelength [65], this feature could be attributed to presence of residual carbonate, as it was explained in the X-Ray diffractogram of this sample, in relation to wide peaks observed.…”

Reexamining the Role of Ammonium Ions in the Sulfidization, Xanthate-Flotation of Malachite

“…Sulfidization converts the surface of oxide minerals of base metals into their sulfide counterparts, and then greatly improves the flotation performances [1][2][3][4]. It is obvious that the sulfidization of oxide minerals is a phase-transition process [5][6][7][8]. Thus, sulfidization process involves dissolution, diffusion, adsorption and chemical reaction [9].…”

Editorial on Special Issue “Surface Chemistry in Mineral Processing and Extractive Metallurgy”

“…Flotation is an important widely used beneficiation process [5], particularly for separating metal sulfides from undesired ones and gangue materials [6][7][8]. An aqueous suspension of a finely ground ore is conditioned with flotation chemicals by changing the surface properties as per the requirements by making the metal sulfides either more hydrophobic (collector) or more hydrophilic (depressant) [9,10]. In the case of collectors, small air bubbles are produced to aggregate with the hydrophobic particles, making them float on the suspension with froth [11,12].…”