Concentration Profiles in Electrowinning Circuits: I . Current Efficiency

Factors affecting the current efficiency of electrowinning processes are investigated theoretically, and the resulting expressions are testing experimentally for the electrodeposition of copper. The results derived predict the dependence of current efficiency on metal‐ion concentration and on total current, for different thermodynamic and kinetic parameters of the electrowinning system. It is found that in rotating disk experiments, where transport parameters are independent of current density, the current efficiency can be approximated by the relationship ∈ = ∈ ∞ [ 1 − exp ( − BC ) / Σ i ) ] . This result is further simplified in a model electrowinning circuit having gas‐evolving electrodes where transport processes depend on current density and current efficiency can be represented with surprising accuracy by ∈ = ∈ ∞ [ 1 − exp ( B ′ C ) ] , where ∈∞ and B ′ are constants which depend on cell geometry and electrolyte composition.