Effect of Jet Flow between Electrodes on the Cathode Quality in Copper Electrorefining with High Current Density

Hongdan Wang,Wentang Xia,Qian Wang,Bingzhi Ren

doi:10.3390/met8100833

Hongdan Wang, Wentang Xia + Show 2 more

Open Access

https://doi.org/10.3390/met8100833

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Abstract

Increasing current density is one of the main methods for improving the productivity of copper electrorefining. However, in the conventional bottom-inlet/top-outlet mode, an increase in current density leads to a deterioration of the surface quality of the cathode copper. This paper describes an experimental study of the influence of the jet flow between electrodes on the cathode quality. The surface roughness and the standard deviation of the cathode copper were used to evaluate the cathode quality. The results showed that in the single-side jet inlet mode, the electrolyte circulation rate has great influence on the surface roughness of the cathode copper, which is inversely correlated. However, when the electrolyte circulation rate is small, the surface roughness of the cathode copper is not uniform. The farther the position at the surface of the cathode copper is to the jet region, the coarser the cathode copper surface, and vice versa.

Highlights

Copper electrorefining is the final process in copper pyrometallurgy to achieve the purity of the product
The electrolysis time is up to 7 days, and it is expected that the surface of the cathode copper will become much coarser at a high current density of 450 A·m−2
In the conventional bottom-inlet/top-outlet mode, the surface roughness and standard deviation of cathode copper gradually decrease with an increasing electrolyte circulation rate, as shown in

Summary

Introduction

Copper electrorefining is the final process in copper pyrometallurgy to achieve the purity of the product. Regardless of the process, in the conventional way of the electrolyte circulation, namely bottom-inlet/top-outlet, an increase in current density leads to an increase in the thickness of the diffusion boundary layer and a depletion of copper ions near the cathode Both particles and streaks occur at the surface of the cathode copper, which eventually cause the deterioration of the cathode quality [1,2]. This technology utilizes a manifold inlet to achieve a parallel electrolyte flow and to introduce the fresh electrolyte directly to the cathode surface Both the copper ion concentration and the temperature of the electrolyte become more homogeneous in the entire cell, which reduces the thickness of the diffusion boundary layer at the cathode and ensures very good cathode quality in copper electrorefining at high current densities. The effects of the electrolyte inlet mode, the electrolyte circulation rate, and the position of the jet on the surface quality of the cathode copper were investigated, providing theoretical guidance for better application of the technology

Experimental Details

Results and Discussion

Conclusions