Insights into the desilication mechanism of goethite by anionic reverse flotation from hydroxyl role

Abstract

This paper mainly investigates the role of hydroxyl on the desilication of goethite by anionic reverse flotation. Accordingly, micro-flotation experiments suggested that the activation effect of Ca(II) on quartz was obviously better than that of goethite in the high alkaline sodium oleate (OL) system.. Furthermore, the Zeta potential also confirmed that the selectivity of Ca(II) ions on quartz surface was better than that on goethite surface. Solution chemical analysis revealed that the dominant species of activator Ca(II) and collector OL were Ca2+ and OL−, respectively. Fourier transform infrared (FT-IR) spectroscopy suggested that OL− could not form an effective adsorption on mineral surfaces in the absence of Ca2+, while OL - had a strong chemisorption in the presence of Ca2+. Density functional theory (DFT) calculations demonstrated that the successful floating of quartz involves three surface modifications, namely the surface hydroxylation, the adsorption of Ca2+ on the hydroxylated surface, and the adsorption of OL− on the Ca2+-activated surface. In this process, hydroxylation is the prerequisite for the subsequent adsorption of Ca2+ and OL−. Besides, the selective adsorption of sodium humate (SHM) causes the flocculation and inhibition of goethite, which also plays a key role in the desilication of goethite.