The production of aluminium, copper, nickel, and zinc commonly involves the use of electrochemical processes.

An electrochemical process is a process where the reactions taking place are driven by electricity. These reactions happen at the electrodes: the anode and the cathode. The electrodes are made of a conducting material, often a metal or a graphitic material. Between the anode and the cathode there is an electrolyte, which is a liquid that can conduct electricity. Electrochemical processes can take place at low temperatures (room temperature) or at high temperatures.

The main challenges that need to be addressed are:

• Reduce energy consumption of the processes and/or
• Elimination of the emission of greenhouse gases with global warming potential.

This requires deep understanding and fundamental knowledge about what happens during the electrochemical processes. That knowledge can be used to adapt existing processes and develop new processes and technologies.

In this research area we work on climate neutral and energy efficient aluminium production, energy efficient copper, nickel and zinc production, and new electrowinning processes for silicon and manganese. Advanced measurement, digital and modelling techniques will be used.

Climate neutral aluminium production

In the existing Hall-Héroult process used for primary aluminium production potent greenhouse gases are generated. Other gaseous compounds have a global warming potential (GWP) much larger than CO₂. For example, CF₄ has a global warming potential (GWP) that is 7390 times larger than CO₂, and C₂F₆ has a GWP 12 200 times larger than CO₂. We will work on reducing the emissions of these and other compounds to reduce the climate footprint. Deepening our understanding on how alumina dissolves into the cryolite-based electrolyte helps in reducing the onset of the so-called anode effect. This knowledge also supports a reduction of the greenhouse gas emissions from the Hall-Héroult process.

Another way to reduce greenhouse gas emissions is by inventing new processes for aluminium production. We will work on bringing the knowledge on inert oxygen-evolving anodes forward.

Energy efficient nickel, zinc, and copper production

Electrowinning and electrorefining processes are used in the production of copper, nickel and zinc and in these processes the anode gas is chlorine which is looped back into a chlorination process. Hence, these industries do not form greenhouse gases while producing their metal product. By using electricity from renewable sources, the goal of zero emission metal production is coming closer. As everyone is transitioning to renewable energy, using the available energy as effectively as possible is key.

Therefore, we will focus on reducing the electricity needed to produce metal by improving the energy efficiency of the process itself. The possibilities for optimization of the processes happening at and on the electrodes will be investigated. Among others, we will look at new electrocatalytic materials to replace the current electrodes to reduce overpotentials at the electrodes and hereby reduce energy consumption. We will also study how the stability of the surface of electrodes can be improved with the aim to produce electrodes with an elongated lifetime.

Electrowinning of silicon and manganese

Today, electrochemical processes are not used in the production of silicon and manganese-based alloys. Electrowinning processes may be a low-emission alternative to the current carbon-based processes.

We will build on the knowledge and insights from the industries that are using electrolysis and the other activities in this research area and the FME ZeMe Centre as a whole. The activities planned will create new knowledge on electrowinning in molten salts and oxides.