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Turkish Journal of Chemistry

PAUL CHIRITA

DOI

-

Abstract

The kinetics of pyrite oxidation in perchloric acid solutions were investigated at temperatures ranging from 30°C to 40°C, potassium dichromate concentration from 0.001 to 0.05 mol L^{ - 1}, particle size fractions from 50 to 150 \mu m and pH values down to 2.83. The rate of the oxidation reaction is described by the following expression: r = bkS^{0.51}[K_{2}Cr_{2}O_{7}]^{0.64}[H^{+} ]^{0.22} where S is the surface area of reacting solid, r represents the amount of Fe release in solution per unit surface area per unit time, b is a stoichiometric factor, k is the rate constant, and [K_{2}Cr_{2}O_{7}] and [H^{+} ] are the potassium dichromate and hydrogen ion concentrations respectively. The magnitude of the activation energy (74.83 kJ mol^{-1}) and the direct relationship between the rate constant and initial pyrite specific surface area are in agreement with a mechanism controlled by a chemical reaction. Trace element content had no statistically significant effect on the oxidation rate.

Keywords

pyrite oxidation, potassium dichromate, activation energy, reaction order, trace element content

First Page

111

Last Page

118

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