Pulp chemistry of sulphide froth flotation

Abstract: The pulp chemistry of chalcopyrite, galena and sphalerite is analyzed theoretically, with computer-aided modelling, and practically with ion chromatography. Ion chromatography is used for analyzing the inorganic and organic anion chemistry of sulphide flotation. The adaptation of modern, rapid analytical techniques to sampling in pulp environments has given valuable information on the metastable state of the processes. Data from the field measurements are then used to construct pulp chemistry models that satisfactorily explain observed phenomena in the flotation of sulphide minerals. The chemical models, presented mainly as predominance diagrams, incorporate the modelling concepts: 'surface molarity' which is the concentration of components emanating from a thin ]aver of the mineral surface. 'thiosulphate metastability' which is modelled through adjusted formation constants of sulphite and sulphate species, 'hydroxoxanthates' as models of metal-xanthate surface compounds/complexes, 'operational line' which describes the pe-pH path of a process point in a pulp chemistry system. Based on current knowledge, one can postulate that the formation of a 1:1-compound on the mineral surface is a pre-requisite for acceptable flotation results, and that the actual flotation area coincides with the formation of the stoichiometric bulk metal-collector compound. The direct ion chromatography measurement of xanthate, perxanthate and monothiocarbonate, implies that on-line optimization of reagent addition and reagent distribution is now possible.