"The aluminum industry produces approximately a million tons of waste by-product from its domestic smelting process, " said Dr. J. Y. (Jim) Hwang, director of the Institute of Materials Processing (IMP) and associate professor of mining engineering at Michigan Tech. "This waste by-product is called salt cake and is skimmed off for disposal during the smelting process. Getting rid of the salt cake costs aluminum producers millions of dollars in land filling and exposes them to environmental liabilities as well."

Hwang said he and his colleagues view salt cake not as a waste product, but as raw material that with further processing can be used to create value-added products that economically enhance the bottom line of the aluminum industry.

"We are developing a technology to divert salt cake into valuable feed stock materials for the manufacturing of concrete products such as lightweight masonry, foamed concrete, and mine backfill grout," explained Hwang. "By using the unique properties inherent in the aluminum salt cake, we can make this by-product function as a foaming (air entraining) agent and as fine aggregate for use in concrete."

Hwang said the new technology will benefit the aluminum, concrete, mining, and construction industries.

"The aluminum industry will improve its competitiveness from increased recovery of aluminum metal and release from its disposal burden and future liability threat," he explained. "The concrete industry is facing a growing building construction demand, especially in the lightweight concrete segment, and in the national overhaul of transportation infrastructure. The incoming processed aluminum smelting by-products will not only ease the concrete industry's material supply pressure, but will also improve its productivity by reducing weight and increasing strength, in addition to reducing materials costs.

"The mining industry is under increasing pressure to backfill mines and quarries that are no longer profitable. With foaming concrete, the mines and open pits can be filled with half the amount of cement used with standard concrete. And the construction industry is looking for alternative building materials due to fluctuating lumber prices and the sagging quality of lumber. Cellular, lightweight concrete products can fill the bill as an economically feasible alternative."

Hwang said the project pulls together researchers from both the University and industry to ensure that the outcome is technically, economically, and environmentally sound and applicable to industry needs. Several Michigan Tech departments will be involved, along with industry representatives from Alcan, IMCO Recycling, Marport Smelting, TIMCO, Master Builders Inc., Besser Company, Golder Associates, Inc., and Down Stream Systems Engineering.

The 4-5 year project will be supported by a $1.6 million contract from the Department of Energy and $.4 million from industry.

Note: If no author is given, the source is cited instead.

• Construction
• Civil Engineering
• Materials Science

• Concrete
• Tensile strength
• Metallurgy
• Hurricane proof building
• Civil engineering
• Mining