Rate controls on the oxidation of heaps of pyritic material imposed by upper temperature limits on the bacterially catalysed process

Abstract: Oxidation of a fraction of the pyrite in gold-bearing pyrite ores before leaching often increases gold recovery rates. There are a number of techniques availablc, one of which is dump oxidation. Commercial viability of such an operation requires a net oxidation of 50% or more in 1 year. This is possible in a dump provided convection is established quickly. Since convection requires temperatures in the dump to be well above ambient, a question arises as to the constraints that might be imposed by the upper temperature limit ( T _kill) of the microorganisms which catalyse the oxidation of the pyrite. Our objective is to investigate, by way of a computer model, the importance of T _kill as a parameter effecting the oxidation rate and the fraction of pyrite oxidised after 1 year in dumps where the goal is to oxidise about 50% of the pyrite in a year or less.