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    Dissolution Kinetics of Chalcopyrite in Acidic Potassium Dichromate Solution
    (Elsevier, 2006) Aydoğan, S.; Uçar, G.; Canbazoğlu, M.
    The dissolution of chalcopyrite in acidic potassium dichromate solution has been investigated with respect to the effects of sulphuric acid and potassium dichromate concentrations, by changing stirring speed, leaching temperature and particle size. It was determined that dissolution rate increased with increasing sulphuric acid concentration, potassium dichromate concentration and temperature. A particle size below 75 mu m was required to leach > 80% copper in 150 min at 90 degrees C. The kinetic study showed that the dissolution of chalcopyrite is represented by shrinking core model with diffusion through a porous product layer of sulphur. The activation energy (E-a) for the dissolution reaction was calculated as 24 kJ/mol. Pyrite dissolution from the concentrate was significant in potassium dichromate solutions because of its high oxidation potential.
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    Dissolution Kinetics of Sphalerite with Hydrogen Peroxide in Sulphuric Acid Medium
    (Elsevier Science Sa, 2006) Aydoğan, S.
    The kinetics of dissolution of sphalerite with hydrogen peroxide in sulphuric acid solution was investigated. The influence of stirring speed (0-600rpm), dissolution temperature (10-60 degrees C), sulphuric acid concentration (0.5-6.0M), hydrogen peroxide concentration (0.1-6M), and particle size were studied. The dissolution kinetics was found to follow a shrinking-core model, with the surface chemical reaction as the rate-determining step. This finding is in concordance with the activation energy of 43 kJ/mol and a linear relationship between the rate constant and the reciprocal of particle size. Increasing concentrations of sulphuric acid and hydrogen peroxide have a positive effect on the dissolution of sphalerite, and orders of reaction of 0.35 and 0.48 were established with respect to sulphuric acid and hydrogen peroxide concentrations, respectively. Stirring speed had no effect on the rate of sphalerite dissolution.