Considerations on the Mechanism of Reaction between Xanthate and Sulphide Minerals

Abstract

In order to study the mechanism of flotation, the phenomena of the collection and the depression were discussed, at first by means of thermodynamics, and then the reaction product on the mineral surface was confirmed by the infrared spectroscopic study. In the thermodynamical discussion of the flotation phenomena, it was postulated that the adsorption of xanthate on the sulphide mineral depends on the chemical affinity. Consequently, the variation of free energy on the reaction between xanthate ion or hydroxyl ion and sulphide mineral was calculated as the function of pH value on the basis of thermodynamics. From the results, the pH range where xanthate ion or hydroxyl ion preferentially reacts on the sulphide mineral was determined. These ranges, respectively, coincided fairly well with those of the collection or the depression for the sulphide mineral flotation. By the infrared spectroscopic study, it was confirmed that the metal xanthate should be produced on the surface of sulphide mineral. Thus, it can be said that the chemical affinity between the sulphide mineral and the flotation reagent is an important factor in flotation.