Selective flotation of galena from sphalerite using a combination of KMnO4 and carboxylated chitosan

Abstract

An effective reagent combination plays a crucial role in the flotation separation of galena and sphalerite. In this work, potassium permanganate (KMnO4) was used to amplify the property difference between galena and sphalerite, carboxylated chitosan (CCS) was used to selectively depress sphalerite. The mechanism of CCS in the separation of galena and sphalerite was investigated by microcalorimetric measurements, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) spectroscopy. The results indicated that the rate of sphalerite oxidation by KMnO4 is significantly faster than galena, and more metal oxides will be produced on the surface of sphalerite. The metal oxides provided active sites for CCS to adsorb on the surface of sphalerite via chemisorption, and the adsorption of CCS hindered the further adsorption of potassium butylxanthate (PBX). Meanwhile, the slower oxidation rate of galena means that fewer metal oxides are produced. In addition, CCS is mainly adsorbed on the surface of galena through physical adsorption, which is easy to fall off, so the surface of galena can further adsorb PBX. Thus, flotation separation of galena and sphalerite is achieved.