The depressing effect of an anionic polyacrylamide on molybdenite flotation and the importance of polymer anionicity

Abstract

Abstract The effect of a carboxylated polyacrylamide (PAM) of 11.9% of degree of anionicity on molybdenite flotation was previously reported. In this work the depressing effect of a polyacrylamide of 8.15% of degree of anionicity (LPAM) on molybdenite flotation under different conditions of mechanical degradation, pH, and concentration is presented. The study of the influence of PAMs anionicity on molybdenite flotation is new and deserved further research. It was found that the non-sheared LPAM had the strongest depressing effect, followed by the moderately sheared LPAM; strongly sheared LPAM did not affect molybdenite flotation. The depressing effect of the LPAM tested in this work on molybdenite flotation and the specific polymer adsorption on the mineral decreased as the pH increased which is opposite to what is observed for more anionic polyacrylamides. These experimental observations suggest that the repulsive forces between the LPAM molecules and the anionic moieties on the molybdenite surfaces outweigh the attractive forces existing between the active polymeric groups and the hydroxylated metal sites on the molybdenite faces. The impact of flocculants in thickening is known, in this work the impact of the anionicity of residual flocculants on the flotation of molybdenite is anticipated.