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 (Tkill) of the microorganisms which catalyse the oxidation of the pyrite. Our objective is to investigate, by way of a computer model, the importance of Tkill 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. © 1993.