Nucleation kinetics of selenium (+4) precipitation from an acidic copper sulphate solution |
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Authors: | M Mangere J NathooAE Lewis |
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Institution: | Crystallization and Precipitation Unit, Department of Chemical Engineering, University of Cape Town, Rondebosch 7701, South Africa |
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Abstract: | The removal of selenium from copper sulphate solution prior to the electrowinning of copper is desirable in order to minimise contamination of the copper cathodes by selenium and other impurities. The selenium removal is effected by a precipitation process that takes place under high supersaturation conditions, which favour nucleation over any other particle formation processes. There is currently no fundamental information on the nucleation kinetics of this important process. In this study, the nucleation kinetics of selenium (+4) precipitation from an acidic copper sulphate solution was determined using the classical nucleation theory (CNT). Experiments were carried out by varying the levels of supersaturation from 8.66×1015 to 4.33×1017 at a temperature of 95 °C under atmospheric pressure. The nucleation rates for four different levels of supersaturation, the nucleation work and the nucleus size were determined. The kinetic constant A was found to be 3.92×1027 m−3 s−1, which shows that the nucleation process takes place through a homogeneous mechanism. The associated thermodynamic parameter (B) was determined to be 8.98×1004. |
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Keywords: | A1 Supersaturation AI Nucleation work B1 Selenium A2 Critical nucleus A1 Homogeneous nucleation |
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