Sulfidization and flotation of chrysocolla and brochantite

A detailed investigation of the physical chemistry of interaction of oxide copper minerals, chrysocolla and brochantite, with aqueous ammonium sulfide solutions has been carried out. The principal experimental variables that have been explored are solution pH, degree of agitation, conditioning time, and sulfide ion concentration. Attempts have been made to assess the change in the surface characteristics of the minerals using gas adsorption (surface area), X-ray diffraction, and microelectrophoresis techniques. The results obtained indicate that sulfide ions interact more intensely and rapidly with oxide copper mineral at acidic pH values than at basic pH values. Sulfidization affects the surface charge characteristics of brochantite more than it does chrysocolla. The porous nature of chrysocolla is hardly reduced by sulfidization. Sulfidization followed by xanthate flotation is a very effective method for the recovery of brochantite irrespective of either sulfidization or flotation pH. Chrysocolla responds rather poorly to flotation even after sulfidization. Conditioning at acidic pH values makes chrysocolla more amenable to flotation.