Modeling Natural Convection in Copper Electrorefining: Describing Turbulence Behavior for Industrial-Sized Systems

Abstract

A computational fluid dynamics (CFD) model of copper electrorefining is discussed, where natural convection flow is driven
by buoyancy forces caused by gradients in copper concentration at the electrodes. We provide experimental validation of the
CFD model for several cases varying in size from a small laboratory scale to large industrial scale, including one that has
not been compared with a CFD model. Previously, the large-scale systems have been thought to be turbulent by some workers
and modeled accordingly with k-ε type turbulence models, but others have not considered turbulence effects in their modeling.
We find that the turbulence model does not predict turbulence exists; however, we analyze carefully the fluctuation statistics
predicted for a transient model, finding that most cases considered do exhibit a type of turbulence, an instability related
to the interaction between velocity and copper concentration fields. We provide a comparison of the extent of turbulence for
various electrode heights, and gap widths, and we emphasize industrial-sized electrorefining cells.