Exploring Cu2O/Cu cermet as a partially inert anode to produce aluminum in a sustainable way

Abstract

As an energy-intensive process, aluminum production by the Hall–Héroult method accounts for significant emissions of CO2 and some toxic greenhouse gases. The utilization of an inert anode in place of a carbon anode was considered as a revolutionary technique to solve most of the current environmental problems resulting from the Hall–Héroult process. However, the critical property requirements of the inert anode materials significantly limit the application of this technology. In light of the higher demand for aluminum alloys than for pure aluminum, a partially inert anode was designed to produce aluminum alloys in a more sustainable way. Here, Cu2O/Cu cermet was chosen as the material of interest. The thermal corrosion behavior of Cu2O/Cu was investigated in Na3AlF6–CaF2–Al2O3 electrolyte at 960°C to elucidate the corrosion mechanisms of this type of partially inert anode for the production of aluminum or aluminum alloys. Furthermore, the effects of the geometrical structure of the Cu phase on the thermal corrosion behavior of Cu2O/Cu cermet in the electrolyte were investigated as well. The thermal corrosion rate was evaluated by the weight loss method and the results show that the samples prepared with branch-like Cu have higher thermal corrosion rate than those prepared with spherical Cu, and the corrosion rate increases with decreasing size and increasing filling content of Cu phase. The calculated corrosion rate was about 1.5–7.2mg/сm2h (1.8–9cm/y) in the current testing procedure. The Cu contents in the produced aluminum is less than 6.2wt.%.