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Interfacial Electrochemistry of Pyrite Oxidation and Flotation

1995; Elsevier BV; Volume: 171; Issue: 2 Linguagem: Inglês

10.1006/jcis.1995.1198

1095-7103

Xianghuai Wang,

Iron oxide chemistry and applications

Infrared spectra of short carbon chain ferric xanthates (Fe(SSCOCR)3) were systematically characterized and compared with that of their corresponding alkali xanthates and dixanthogens. Ferric xanthates display an intense absorption band at the frequencies of 1260-1235 cm-1 (in KBr), depending on the carbon number of the alkyl chain. The bands have been assigned to the asymmetric stretching vibration of C-O-C linkage. The absorption bands shift to lower frequencies in organic solvents like carbon tetrachloride. The position of the C-O-C bands in the corresponding dixanthogen appears at higher frequencies in the range of 1260-1270 cm-1 and shows no shift in the organic solvents. The adsorption of short chain xanthates on the surfaces of synthetic high purity pyrite microcrystalline in neutral pH solutions has been investigated. Both dixanthogen and ferric xanthate characteristic IR peaks have been observed. The quantity of dixanthogen is much greater than that of ferric xanthates for all the xanthates studied. For the pyrite-ethyl xanthate system, when the xanthate-reacted pyrite is rinsed with hexane, nearly all the dixanthogen formed on the pyrite surfaces is washed away. The remaining spectrum of the washed xanthatedpyrite resembles that of the corresponding ferric xanthate. In addition, a sharp peak has been observed at 1090 cm-1 on the hexane-washed pyrite surfaces, possibly indicating that ethyl xanthate ions are specifically adsorbed on pyrite surfaces. These results suggest that ferric-xanthate compounds are formed in the pyrite-xanthate systems as surface compounds on the pyrite surfaces and/or as a separate precipitate phase in the bulk solution.