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Alcoa outlines technology roadmap to decarbonize aluminum industry

Alcoa Corp. outlined a technology roadmap to support its vision to reinvent the aluminum industry for a sustainable future. The technologies in Alcoa’s roadmap, including a new, proprietary post-consumer scrap recycling process, have the potential to decarbonize a significant portion of the upstream aluminum supply chain and provide a competitive advantage in a carbon-constrained world.

The roadmap includes three key programs:

  • The Refinery of the Future, which aims both to reduce the capital cost of developing a refinery and to enable decarbonization of the alumina refining process. Alcoa would use a combination of processes and technologies that are under development, including mechanical vapor recompression and electric calcination to develop this future-focused design.

  • The ASTRAEA metal purification process developed by Alcoa for recycling post-consumer, aluminum scrap into high-purity aluminum. The process could create an entirely new value chain to economically produce aluminum of a quality that far exceeds the purity of the commercial-grade aluminum produced in a smelter.

  • The ELYSIS joint venture technology that eliminates all greenhouse gases from the traditional smelting process. (Earlier post.) The process uses next-generation electrode design and proprietary materials first developed at the Alcoa Technical Center and emits pure oxygen as a byproduct at a lower operating and capital cost than conventional technology.

The Refinery of the Future: Targeting zero-carbon emissions alumina refining. Alcoa’s Refinery of the Future program will use a range of technologies and processes to design a refinery that lowers capital intensity, eliminates carbon emissions, and addresses other industry challenges, including reducing or eliminating bauxite residue.

From the environmental perspective, it will be designed around two technologies: mechanical vapor recompression (MVR) and electric calcination, which allows for a self-enclosed calciner operating environment that captures steam and allows the calciner to be connected to a renewable-powered electric grid. The technology also retains all the water from the original feedstock.

When combined with a decarbonized grid, these two technologies enable a pathway to a zero-emissions alumina refining system.

MVR is a renewable energy-powered process that recycles low-pressure steam in the refining process, offering the potential to reduce carbon emissions in alumina refining by up to 70 percent. Alcoa is currently evaluating the application of this technology in Australia with support from an $11-million grant from the Australian Renewable Energy Agency (ARENA). (Earlier post.) The process reduces water consumption by up to 35%.

The ASTRAEA technology: Enabling a new value chain to create high purity aluminum. Alcoa has developed a patented process to purify any post-consumer aluminum scrap into a purity level of P0101, surpassing the purity of P1020 aluminum that is produced at any commercial smelter. Today, there is a vast supply of aluminum scrap that can only be used for limited applications due its combination of impurities.

As feedstock for this process, Alcoa is targeting Zorba auto shred scrap as a raw material. The Institute of Scrap Recycling Industries (ISRI) in the US defines Zorba as shredded mixed non-ferrous metals consisting primarily of aluminum generated by eddy-current separator or other segregation techniques.cToday, there are no commercially available processes to strip this scrap of trace metals and bring it to the suitable purity for most rolling or extrusion applications. Alcoa’s ASTRAEA process is the first and only technology that can purify this low-value scrap.

By converting this low-value, aluminum scrap into high purity aluminum, the ASTRAEA process enables manufacturers to blend with lower-purity scrap, significantly increasing the pool of post-consumer scrap that can be used as a raw material once more. It also allows some specialty aerospace and defense applications to use scrap, which would be a first for those industries.

ELYSIS: Decarbonizing aluminum smelting. The ELYSIS joint venture is built around a zero-carbon smelting technology invented by Alcoa that has the potential to revolutionize how aluminum is made by removing all carbon dioxide emissions from the traditional aluminum smelting process, while lowering operating costs and improving productivity.

ELYSIS recently announced that it is now producing metal with the carbon-free smelting process at its Industrial Research and Development Center, using a full industrial design. The design is similar in size to small, commercial smelting cells in operation today. Also, metal produced from the ELYSIS process has been used by companies such as Apple and Audi.

ELYSIS expects its technology can be offered for commercial application as soon as 2024 with installation by smelting customers possible approximately two years later. The joint venture intends to operate a commercial-scale prototype of the technology in 2023, and construction of prototype cells operating on an electrical current of 450 kA currently underway. These cells are designed to be used as a ‘drop-in’ replacement to retrofit existing smelters or build new ones and can be scaled to other sizes as needed.

The technology roadmap also helps support Alcoa’s pathway to reaching its ambition to achieve net zero greenhouse gas (GHG) emissions by 2050 across its global operations, including Scope 1 and Scope 2 emissions.


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