A study of surface properties of chrysocolla as related to sulfidization and flotation

Abstract

The surface properties of chrysocolla are related to its amenability to sulfidization and flotation. Micro flotation techniques are applied to define more clearly the parameters effecting collectable and noncollectable surfaces and to further the understanding of chrysocolla flotation by sulfidization. Two of the parameters that affect the recovery of sulfidized chrysocolla are the attainment of a stable surface, produced by aging, and the pH at which the chrysocolla is sulfidized. Aging of sulfidized chrysocolla accompanied by a rejection of sulfur, believed to be as H2S, resulted in flotation recovery increasing from 3.54 percent to 81 percent. The recovery of aged sulfidized chrysocolla increased from 36 percent on material sulfidized at pH 5.40 to 89 percent when sulfidized at pH 4.00. The concentration of the sulfidizing solution, above a required minimum, is not an important parameter effecting flotation recovery. Although the concentrations of the sulfide and bisulfide ions increase with increasing pH value, the adsorption of sulfur on the chrysocolla surface decreases. This indicates surface conditions dependent upon pH. These surface conditions are measured as a function of pH by electrokinetic measurements, and indicate a region of increasing incipient leaching of copper as a result of decreasing pH. The volume of sulfidizing solution and the minimum concentration of sodium sulfide for sulfidization of chrysocolla are also important parameters. Activities of both the sulfide and bisulfide ions below 200 mg/1 of 63 percent Na^S appear to be too low to effect sulfidization and a minimum weight ratio of sulfidizing solution to mineral sulfidized of 100 to 1 is sufficient to maintain a constant sulfide ion concentration throughout sulfidization.