Transient modeling of zinc extraction with D2EHPA in a Kühni column

• Zinc extraction with D2EHPA was simulated in a transient operation column.
• A comparative analysis between back-mixing and forward-mixing models was done.
• Both models described column operation adequately under evaluated conditions.
• Back-mixing model is advantageous to describe well stirred conditions.

The transient extraction of zinc sulfate with D2EHPA (di-2-ethylhexyl phosphoric acid) in a section of a Kühni column operated with total recirculation of liquid phases was modeled using the back-mixing and the forward-mixing approaches. The mathematical developments for both models as well as their numerical solutions are given in detail. Operating parameters were calculated using recommended correlations available in the literature and simulations were confronted with experimental data. Both models revealed to describe column operation adequately under evaluated conditions. In addition, as back-mixing and forward-mixing approaches are particularly equivalent in very stirred conditions, the former approach seems to be more advantageous to describe practical situations due to its simplicity in comparison to the later approach.