Interactions between sulphide minerals and alkylxanthate ions. Part 4.—Vibrational spectroscopic and calorimetric study of the interactions between galena and synthetic lead(II) sulphide, and alkylxanthate ions in aqueous, acetone and acetonitrile solutions
The reactions between galena and synthetic lead(II) sulphide powders, and potassium alkylxanthates have been studied in aqueous, acetone and acetonitrile solutions. Acetone and acetonitrile have been used since potassium and lead(II) alkylxanthates are soluble in these solvents. Qualitative analysis of the alkylxanthate species present on the surfaces of galena and synthetic lead(II) sulphide after treatment with alkylxanthate ions has been made by means of diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy. Solid lead(II) alkylxanthate is formed on oxidized galena and lead(II) sulphide surfaces. Alkylxanthate ions are co-ordinated to lead sites in the ultimate surface layer as alkylxanthate complexes on synthetic lead(II) sulphide surfaces when soluble lead(II) compounds are removed. Two types of complex adsorbed onto galena and lead(II) sulphide surfaces have been found. One of these complexes resembles similar complexes on zinc(II) and cadmium(II) sulphide surfaces. This chemisorbed complex is formed in all solvents studied. The other kind of complex is formed only in acetone and acetonitrile solutions. It displays a unique vibrational spectrum and it is formed in a non-exothermic reaction. This complex may result from an electrostatic interaction between a charged particle and alkylxanthate ions.