On the Critical Flotation Condition of a Sulfide Mineral Having Two Kinds of Positive Sites for the Anionic Collector and Depressant Adsorption

Abstract

The critical flotation condition for the sulfide mineral having two kinds of positive sites was discussed from the viewpoint of the competitive adsorption of anionic collectors and depressants by means of statistical mechanics and chemical thermodynamics. On the basis of the statistical mechanics as to the collector-depressant equilibria, the familiar Barsky relation was derived for the double positive site mineral. The Barsky constant can be dependent on all of the collector and depressant adsorptions for each kind of reaction site on the mineral surface according to their adsorption property. In the chemical thermodynamics investigation, the chalcopyrite (CuFeS₂)-xanthatehydroxyl ion system was considered. The chemical affinities of the xanthate ion and the hydroxyl ion onto the positive sites of CuS and FeS, respectively, were calculated, using thermodynamical data for the system. Consequently, it was ascertained that the depressing action of the hydroxyl ion for chalcopyrite was mainly connected with the adsorption of the hydroxyl ion onto the positive site due to FeS, while the collecting mechanism of the xanthate ion for the same mineral is closely related to the adsorption of the xanthate ion onto the positive site due to CuS. The chalcopyrite (CuFeS₂)-xanthate-cyanide ion and hydroxyl ion system was also considered in a similar manner. The flotation-nonflotation condition of chalcopyrite was able to be determined by considering the xanthate adsorption on the positive site due to CuS and the cyanide ion adsoprtion on the one due to FeS.