Kinetics of Aqueous Pyrite Oxidation by Potassium Dichromate - An Experimental Study

Authors : Paul Chirita

Pages : 111-118

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Publication Date : 9999-12-31

Article Type : Makaleler

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 m m and pH values down to 2.83. The rate of the oxidation reaction is described by the following expression: r = bkS0.51[K2Cr2O7]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 [K2Cr2O7] 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