When applied to steelmaking the CCU/S process involves capturing the CO₂ contained in blast furnace waste gases using a chemical solvent, extracting the CO₂ from the solvent, and putting it under low pressure. This allows the CO₂ to be re-used in furnaces or stored away. The process also yields heat, which can be harnessed to reduce the operating cost of furnaces. CCU/S therefore has the potential to reduce dependence on fossil resources and contribute to the decarbonisation of steelmaking.

Developed over a decade of research, the DMX™ process reduces the energy intensity of CCU/S by nearly 30%. This is made possible by using heat-recovery methods, as well as a patented demixing solvent, the DMX™ solvent, created and marketed by our partners in the 3D Project. Not only is the DMX™ solvent more chemically stable than the aqueous monoethanolamine (MEA) solution commonly used in CCU/S today, it also has a higher capture capacity, making it both more efficient and cost-effective.

Upon contact with CO₂-laden waste gases, the DMX™ solvent – composed of two amines in an aqueous solution – splits (or demixes) into two separate liquid phases. The CO₂ becomes concentrated in only one of these liquid phases. The DMX™ process thus yields a smaller volume of CO₂-rich liquid solvent. By extension, it consumes less energy in the subsequent regeneration phase of the CCU/S process, in which the CO₂ is stripped from the liquid solvent by injecting steam.

The 3D Project, launched in 2019, involves building a DMX™ Demonstration plant at ArcelorMittal Dunkirk. By demonstrating that the DMX™ process can successfully be applied on an industrial scale, the Project could significantly cut the cost of CCU/S, making it replicable across heavy industrial sites like ArcelorMittal’s steel mills and many more. The 3D Project will also play an essential part in the design of the future European Dunkirk-North Sea Cluster, which aims to capture, pack, transport, and store away 10 million tonnes of CO₂ per year and should be operational by 2035. The cluster will be supported by the packing and transport infrastructure developed for the government of Norway’s carbon capture and storage project, Northern Lights.

An important milestone in the 3D Project was reached recently: the first modules of the DMX™ demonstrator, which include a 22-metre tower, were assembled at our plant in Dunkirk. The civil engineering will soon be completed, marking the end of the construction phase, and enabling the connection of the DMX™ demonstrator to the steel plant. Once joined, the demonstrator will be capable of capturing approximately 4,400 tonnes of CO₂ per year from steel-mill gas.

The CO₂ extracted from the DMX™ process is extremely pure (99.7%) and can be pressurised at up to 7 bars to facilitate subsequent transport by boat or pipeline. Each tonne of CO₂ captured through the DMX™ process will cost between €30 and €40, generating savings of between €10-€20 per tonne of CO₂ – CCU/S costs currently run up to €50 per tonne. The first tests of the DMX™ demonstrator will begin in March 2022.

The 3D Project is supported by the European Union’s research and innovation programme, Horizon 2020. It has a €19.3-million budget spread over four years, including €14.8 million in European Union subsidies. The Project marks a high point in ArcelorMittal’s efforts to reduce its CO₂ emissions in Europe by 35% by 2030. It brings together eleven stakeholders from research and industry, all from six different European countries – these include ArcelorMittal, Axens, Total, ACP, Brevik Engineering, CMI, DTU, Gassco, IFPEN, RWTH and Uetikon.