Effect of calcium ions and citric acid on the flotation separation of chalcopyrite from galena using dextrin

Using NaOH to adjust pH, dextrin selectively depressed galena while chalcopyrite was floated with a xanthate collector. However, when the pH was adjusted with lime, or when calcium ions were present in the pulp, the flotation of galena was “restored” while chalcopyrite was depressed in an alkaline pH, causing deteriorated flotation separations. It was found that calcium ions adsorbed preferably on chalcopyrite surfaces but not on galena, thus increasing the adsorption of dextrin on chalcopyrite. The addition of citric acid was found to eliminate the detrimental effects of calcium ions and to restore the selectivity of chalcopyrite-galena separation using dextrin.