Modeling of selenium and tellurium removal from electrowinning solution

In this study, the kinetics of selenium and tellurium reduction by cuprous ions were reviewed and a comprehensive model capable of predicting the rate constants for various Cu+2-H2SO4 compositions and temperatures is presented. The rate constant data were fitted to the relationship: In k(1) = (A+B/T) + (C + D x In [H2SO4]) + (E + F([Cu2+](0.5)/1+[Cu2+](0.5)) where k(1) is in M(-1)s(-1) and [Cu2+] and H2SO4 are in molar at temperature T (K), and A to F are empirical constants. The model was validated using different rate constant data points obtained during the reduction of Se-VI and Te-VI under different solution conditions. The rate constant k(1) given by the comprehensive model was within a +/- 3.3% for Se-VI and +/- 5.1% for Te-VI reduction reactions compared to the rate constant determined using the experimental data. The model was used to estimate the selenium and tellurium reduction reaction times under Vale's (Sudbury, Canada) Electrowinning Department (ED) plant conditions. As a result, potential factors that may affect the selenium and tellurium removal rate at the ED plant of Vale were proposed and discussed. (C) 2015 Elsevier B.V. All rights reserved.