June/July 2007

Alcoa launches new clean technology

Alcoa has launched an innovative new technology at its Kwinana alumina refinery in Western Australia that has the potential to deliver significant global greenhouse gas benefits and will contribute to a reduction in the aluminum industry’s environmental footprint.

Alcoa’s ‘Carbon Capture’ system is a residue treatment process that involves mixing bauxite residue, a byproduct of the aluminum-making process, with carbon dioxide. This locks up large volumes of CO2 that would otherwise be released into the atmosphere. The Kwinana carbonation plant will lock up 70,000 tons of CO2 per year, the equivalent of eliminating the emissions of 17,500 automobiles.

As part of its ongoing commitment to reduce its global emissions, Alcoa has plans to deploy the technology to its nine alumina refineries worldwide. Deployment across the company’s operations in Australia alone could potentially save 300,000 tons of CO2

The ‘Carbon Capture’ system was developed by Alcoa’s Technology Delivery Group, the company’s global refining research and development unit, based in Australia. Bauxite residue is a mixture of minerals, the by-product of when alumina is removed from bauxite. Although it is thoroughly washed, the residue retains some alkaline liquor and requires long-term storage. By mixing CO2 into the bauxite residue, its pH level is reduced to levels found naturally in alkaline soils. A second sustainability benefit is the improvement of environmental properties of the residue, which means it also can be beneficially used as road base, building materials, or to improve soil.

Alcoa plans to share the technology within the aluminum industry.

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