Activation of sphalerite by Cu ions produced by cyanide action on chalcopyrite

Cyanide used as a depressant for pyrite in the flotation of chalcopyrite from a polymetallic ore was found to result in flotation (activation) of sphalerite. This was thought to be due to leaching of copper ions from chalcopyrite by the cyanide. Copper leached from specimen chalcopyrite and from a Cu-ore sample treated with cyanide was determined for a variety of conditions. A significant increase in Cu release at elevated pulp potential is shown which also enhanced uptake of Cu ions by sphalerite. Activation, it is suggested, is related to release of copper as cuprocyanide and subsequent oxidation to cupric cyanide, which supplies the Cu2+ ions.