Effect of pyrrhotite reactivity on cyanidation of pyrrhotite produced by pyrolysis of a sulphide ore

摘要

The effect of the metal to sulphur ratio in thenonstoichiometic compound ,pyrrhotite ,is related to theconsumption of cyanide in gold leaching .Reactive pyrrhotite(Fe(1-X)S) is produced during the pyrolysis of refractory pyrite(FeS2) .Iron vacancies give pyrrhotite its non stoichiometricnature and determine its fugacity and hence reactivity .Separatetrends for cyanide consumption were found when pyrite waspartially converted to pyrrhotite compared to where all the pyritewas converted to pyrrhotite .Samples that were partiallyconverted to pyrrhotite ,and hence remained in equilibrium withthe unconverted pyrite ,showed an increase in cyanideconsumption with increasing metal to sulphur ratio .Samples inwhich all the pyrite was converted to pyrrhotite showed adecrease in cyanide consumption with an increasing metal tosulphur ratio .For all samples the higher the pyrolysistemperature the lower the cyanide consumption.