The stability of the copper-iron sulphides

✍ Scribed by P. A. Young

• Publisher: Springer
• Year: 1967
• Tongue: English
• Weight: 70 KB
• Volume: 2
• Category: Article
• ISSN: 0026-4598
• DOI: 10.1007/bf00201922

✦ Synopsis

Calculations are presented for the free energies of formation, AG°f.z~s for cubanite, bornite, chalcopyrite and idaite. The writer reviews earlier work, and, in particular, that of MERWlN andLOMBARD (1937) and of BARTHOLOM~ (1958). The sulphur vapour pressure data of MERWlN and LOMBARD (1937) provide one possible basis for calculation, but subject to a lack of information on heat capacities and latent heats of transformation which makes extrapolation ~rom higher to lower temperatures difficult. It is also necessary to relate the decomposition pressures to specific reactions, and here there is some ambiguity in the published work on mineral assemblages. Bearing these problems in mind the writer calculates free energies for cubanite, bornite and chalcopyrite, assuming diatomic sulphur vapour, and proceeds to calculate the error which has been introduced by ignoring the true state of molecular aggregation of sulphur vapour. The criticisms which the writer applies to his own calculations are then applied to those of GOLOMZlIC (1964). The work of BARTHOLOMI~ (1958) and of YUNI) and KULLERUD (1966) provide a firmer basis for