Dr. Jim Hwang, director of the Institute of Materials Processing (IMP) and associate professor of mining engineering at Michigan Tech, is developing a technology to divert aluminium smelting waste products, into feedstock materials for the manufacture of concrete products such as lightweight masonry, foamed concrete, and mine backfill grout.

The aluminium industry produces approximately a million tons of waste by-product from its domestic smelting process. This waste by-product, salt cake, is skimmed off during the smelting process. Getting rid of the salt cake costs aluminium producers millions of dollars in land filling and exposes them to environmental liabilities.

“By using the unique properties inherent in the aluminium salt cake, we can make this by-product function as a foaming (air entraining) agent and as fine aggregate for use in concrete,” said Hwang.

“The aluminium industry will improve its competitiveness from increased recovery of aluminium metal and release from its disposal burden and future liability threat. 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 aluminium 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.”

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.

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