Application of electrochemical kinetics to elucidate the leaching mechanism in the bio-oxidation of a synthetic nickel sulphide
Date
2015-02-06
Authors
Huberts, Robert
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Abstract
The importance of the direct and indirect mechanisms in
the bacterial leaching of a synthetic nickel sulphide is
investigated using an electrochemical leaching model.
Sterile controls runs, in which only ferric leaching
took place, are compared with runs in the presence of an
active, adapted bacterial culture.
The direct mechanism occurs when bacteria attach to the
sulphide mineral and catalyze the oxidation of the
mineral, presumably with enzymes (biological catalysts).
No evidence was found of the direct mechanism, in fact
ferric leaching appeared to be inhibited as the bacterial
presence increased due to growth. Considering
evidence obtained by the fitting of the electrochemical
model, it is tentatively suggested that leaching of the
mineral is largely due to chemical ferric leaching, with
the leaching role of bacteria restricted to re-oxidizing
the resulting ferrous ions. Whether this is the case
for other minerals remains to be established.