The pyrite oxidation rate is a process central to both the performance of
bio-oxidation heaps, used in the pre-treatment of some refractory gold
ores, and to the levels of pollution in acid rock drainage (ARD) from
pyritic waste rock dumps. A goal in bio-oxidation heaps is to achieve
high oxidation rates in the heap as a whole. In comparison, one way to
mitigate the environment impact of ARD, is to reduce the overall
oxidation rate in the waste rock dump since pyrite oxidation is the
primary pollutant generation process. In both bio-oxidation heaps and
waste rock dumps the overall oxidation rate of the pyritic material (the
intrinsic oxidation rate) at these sites. Much research has been conducted
over the last 40 years or so on the oxidation rate of pyritic material with
particular emphasis on the catalytic role played by bacteria. More
recently mathematical models and field measurements have clarified the
extent to which oxygen transport rates are rate limiting, what the
dominant oxygen transport mechanisms are and the physical properties of
the heaps which have most impact on these transport rates and on the
overall oxidation rate. How the performance of bio-oxidation heaps can
be optimised and how the pollution load in drainage from waste rock
dumps depends on gas transport mechanisms is briefly reviewed. The
sensitive of the overall oxidation rate in bio-oxidation heaps and waste
rock dumps to details of the intrinsic oxidation rate is quantified.