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Modelling cobalt solvent extraction using Aspen Custom Modeler
Journal article   Peer reviewed

Modelling cobalt solvent extraction using Aspen Custom Modeler

H.A. Evans, P.A. Bahri, L.T.T. Vu and K.R. Barnard
24th European Symposium on Computer Aided Process Engineering, Vol.33, pp.505-510
2014
DOI: https://doi.org/10.1016/B978-0-444-63456-6.50085-5
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Abstract

The cobalt solvent extraction system using Cyanex 272, a phosphinic acid based extractant, has been modelled using the Aspen Custom Modeler mathematical modelling software. The principle advantage of this method is that the model can easily be imported into Aspen Plus and run as part of an integrated flowsheet containing other unit operations. The cobalt solvent extraction circuit operates on a counter-current basis, with the barren organic entering the final stage and the aqueous feed entering at the first stage. Since the metal extraction efficiencies were dependent on the conditions of the outlet streams, a solver must be selected to simultaneously solve a set of algebraic nonlinear model equations. Initial sensitivity analysis for a single stage Aspen Custom Modeler model has shown that increasing pH or the organic to aqueous (O:A) ratio significantly increases individual metal extraction efficiencies. To achieve the ultimate aim of maximising cobalt extraction while minimising magnesium and nickel co- extraction and reagent consumption, an economic objective function has been formulated within the optimisation problem to solve for the optimum pH setpoint and O:A ratio. The optimised single stage results indicate operating at pH 4.5 and O:A of 0. 78 to achieve 95% cobalt extraction, while limiting nickel extraction to <1%.

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