Influence of surface oxidation rate on the flotation of sphalerite and galena inhibited by gum arabic

Abstract

Differences in the flotation behavior of galena and sphalerite using potassium permanganate (KMnO₄) and gum arabic (GA) alone and using a mixture of KMnO₄ and GA were investigated. The single mineral flotation tests revealed that when KMnO₄ and GA were used individually, galena and sphalerite flotation were inhibited, but the reagent dosages required were large. Sphalerite was strongly inhibited by the addition of a tiny amount of GA after oxidation with KMnO₄ while galena was not inhibited under the same conditions. Following oxidation by KMnO₄, galena and sphalerite exhibited a significant 83 % difference in flotation recovery when 10 mg/L GA was used, which clearly showed the potential for the combined use of KMnO₄ and GA to achieve flotation separation of galena from mixed lead-zinc ores. The inhibitory effect of GA on sphalerite was investigated through a combination of analytical techniques, including Microcalorimetry, Fourier Transform Infrared (FTIR) Spectroscopy, contact angle measurements, X-ray Photoelectron Spectroscopy (XPS), and Scanning Electron Microscopy (SEM) coupled with Energy Dispersive X-ray (EDS) analysis. The results displayed that sphalerite had a much higher oxidation rate than galena, resulting in more oxides and hydroxides. As a result, the sphalerite surface exhibits an increased availability of active sites favorable to GA adsorption, thereby impeding Butyl xanthate (PBX) adsorption. However, the galena surface was able to absorb PBX, resulting in mineral separation.