The Norwegian aluminium industry (Alcoa and Hydro) has two competing long-term strategies (ELYSIS, Alcoa and HalZero, Hydro) towards a replacement of the Hall-Héroult process. Direct research on these technologies will not be part of the FME ZeMe in the start phase of the project due to issues of confidentiality and intellectual property. In this task focus will be on 1) reducing potent greenhouse gas emissions i.e., CF₄ and C₂F₆ in the existing Hall-Héroult process, 2) the direct electrolytic production of Al alloys, and 3) developing a novel emission free process based on inert anodes.

CF₄ and C₂F₆ are typically released when aluminium oxide levels reach a critically low concentration in the electrolyte, and the anode reaction product shifts from CO2 to CF₄ and C₂F₆, so called anode effect. By increasing the understanding of the mechanisms of CF- formation in the electrolysis cells, cell gas studies, Societal and Industry-oriented Research Centre FME 2023 - ZeMe 5 and low-voltage/early onset anode effects the onset of these can be reduced and hence reduce emissions (PhD 1A at NTNU). SINTEF is currently developing a device for measuring the oxide content in situ an electrolysis cell called OxiSens which will be used to investigate the aluminium oxide distribution inside the electrolysis cells as a support task for PhD student 1A.

Electrolytic production of Al alloys will be investigated by PhD 1B at Reykjavik University. Furthermore, SINTEF will gain knowledge on candidate materials for inert anodes, study lifetime, and degradation mechanisms of the materials, and identify ways to recycle the materials at end of life. The work will not be part of the ELYSIS process of Alcoa but base its starting point from available literature and evolve from there.

Energy efficient nickel, zinc, and copper production

Three different approaches of reducing the energy consumption in the Ni, Zn, Co, and Cu industry will be evaluated in this task i.e., energy reduction in aqueous electrowinning 1) through optimization of the cathode process, 2) through optimization of the anode processes and 3) through advanced digitalization and instrumentation. Special focus in the optimization of the cathode process will be on investigating how the morphological stability of the electrodes can be improved, and on how morphological instabilities can be avoided. For the anode process, novel electrocatalytic layers will be developed and tested as potential replacement to the state-of-the-art lead-based anodes. For this, it is suggested to utilize the acid-stable periodic table proposed by Wang et al. Optimization of the catalysts and its activity will be investigated by studying its stability using an electrochemical flow cell directly connected to an inductively coupled plasma mass spectrometer (ICP-MS). Selection of catalyst will be partly based on Bayesian optimization and partly on physical considerations such as those in Wang et al., which can be included in the optimization loop. Optimization of the anode and the cathode processes will culminate to two PhDs at NTNU (PhD 1C and PhD 1D).

Electrowinning of silicon and manganese

Towards the end of the FME ZeMe the production of silicon-based and manganese alloys through electrowinning will potentially be evaluated. Alloys can be produced directly without mixing in a subsequent step by tuning the electrochemical potential when running experiments in molten salts or oxides. This task will depend on the results of the on-going KSP ZeSim project. A synergy from the other industries in the FME traditionally using electrolysis is expected in terms of evaluation of implementation.