Case Studies

These case studies illustrate how Alcoa is acting upon its commitment to sustainable development throughout the world. We are pleased with this progress, but look forward to achieving even more.

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Residue Carbon Capture Delivers Double Environmental Benefit


Brazil - 2008

Turning Industrial Waste into Commercial Products


Production wastes from Alcoa’s Brazilian refineries and smelters are being diverted from the landfill and converted into commercially viable products—minimizing their environmental impact and providing a new source of revenue.

One of Alcoa’s key sustainability goals is to have zero landfilled waste by 2015. In an effort to help achieve that goal, the company has developed a global framework for evaluating and then commercializing its industrial waste for re-use in other industries. There are six stages to the process:

  • Develop concept;
  • Feasibility and lab work;
  • Bench, small-scale testing;
  • Pilot plant scale plus demonstration;
  • Plant/re-use demonstration phase; and
  • Plant implementation.

At each stage, the concept must undergo technical and environmental assessment, commercial analysis, and stakeholder engagement. In addition, any proposed waste re-use must be in accordance with environmental laws and Alcoa standards for waste management.

Beginning in 2008, customers must be certified and audited by a third-party company to ensure they are in compliance with the requirements for handling, storing, and using waste approved for commercial use.

In Brazil, Alcoa’s Department of Applications, Development, and Special Product Sales has made significant progress in converting a number of major refining and smelting wastes into commercial products.

Carbon Cryolite
This waste, which results from the Soderberg smelting process, has been developed into an alternative fuel for the cement sector. Alcoa’s Poços de Caldas smelter sells approximately 1,000 metric tons each month, which will allow it to eliminate all of this stored waste by mid-2009. The smelter has not produced any carbon cryolite since 2003.

Aluminum Oxide Dust
Since 2004, Poços de Caldas has been selling all if its alumina oxide dust collected from the calciner department at the refinery as an alumina source for the enrichment of chamot—an inexpensive refractory aggregate. A second application for the dust is being developed for the Alcoa smelter in São Luís, Brazil, which is located too far from most refractory producers.

Boiler Coal Dust
São Luís is currently selling the coal dust generated from its boilers as another alternative fuel source for the cement industry. Almost 12,000 tons of the dust is being diverted from the landfill each year.
Other wastes that are either being sold or provided to other industries include some mineral wastes as well as spent pot lining (SPL), which is generated when the carbon and refractory lining of smelting pots reaches the end of its serviceable life. Currently, Alcoa’s two Brazilian smelters are providing 30,000 metric tons of SPL annually to the cement industry to use for fuel and a source of fluoride.

The Brazilian locations are also investigating several potential commercial applications for bauxite residue, the largest volume waste of the refining process. They are working closely in this effort with Alcoa’s Australian researchers, who are also developing processes to convert the residue into a raw material for a variety of applications. Primary initiatives including converting the residue for use in the ceramic tile, agriculture, and cement industries.