Selective depression of pyrite with polyacrylamide polymers

Low molecular weight polyacrylamide (PAM) polymers were used to separate copper-activated sphalerite from pyrite in the presence of isobutyl xanthate (IBX). The effects of carboxyl, sulfonate, hydroxyl or thiourea functional groups attached to the polymers on the flotation recoveries of sphalerite and pyrite were studied as a function of polymer concentration and order of reagent addition. It was found that all the PAMs depressed pyrite flotation with no or little depression of sphalerite. The following order for pyrite depression was obtained: hydroxy > carboxyl greater than or equal to thiourea > sulfonate, and for mineral selectivity: carboxyl greater than or equal to sulfonate > hydroxy much greater than thiourea. It was also found that a greater mineral depression was obtained for the coarser particles and when the PAMs were added before the collector. (C) 2001 Elsevier Science B.V. All rights reserved.