‘Carbon Capture’ Technology Launched
Process Mixes Bauxite Residue with Carbon Dioxide To Limit Alumina Refineries’ GHG Emissions

Alcoa has launched a new technology at its Kwinana alumina refinery in Western Australia that has the potential to deliver significant global greenhouse benefits.

The company’s “carbon capture” system is an innovative residue treatment process that involves mixing bauxite residue—a by-product of the aluminum-making process—with carbon dioxide (CO2). The process delivers environmental benefits by locking up large volumes of CO2 that would otherwise be released into the atmosphere.

The carbon-capture process has the potential to deliver significant environmental benefits by effectively locking up the CO2 in a greenhouse sink.

Bauxite residue is a mixture of minerals that are left behind 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 that the improved environmental properties of the residue mean it also can be beneficially used as road base, as a building material, or to help improve soil.

When operating at full capacity, the Kwinana carbonation plant will treat all of the residue produced by the refinery. 

According to Wayne Osborn, the managing director of Alcoa of Australia, the Kwinana carbonation plant will lock up approximately 70,000 tons of CO2 per year—which he said is the equivalent of eliminating the emissions of 17,500 automobiles.

As part of its ongoing commitment to reduce its global emissions, Alcoa plans to deploy the technology to its nine alumina refineries worldwide. Deployment across Alcoa's operations in Australia alone could potentially save 300,000 tons of CO2 each year—the equivalent of removing 75,000 cars from the road, the company says.

The carbon-capture system was developed by Alcoa's Technology Delivery Group, the company's global refining research and development unit, which is based in Australia.