Making Combustion Byproducts Pay

No matter how quickly gasification may be adopted for new power plants, coal-burning plants will still be around for years to come. While clean-coal technologies to control polluting emissions cut down greatly on the atmospheric waste such plants produce, they inevitably increase the amount of solid waste.

For example, smokestack scrubbers to remove sulfur produce tons of scrubber sludge, almost all of which is landfilled. Another major type of coal waste, fly ash, has been used for several decades in concrete, but clean-coal technologies such as fluidized bed combustors produce fly ash with different, little-tested properties, along with heavier bottom ash.

SIUC researchers have been leaders in figuring out ways that companies can turn this waste into useful products instead of paying to dispose of it. Current projects, some of which have been featured in Perspectives, include:

• Using fly ash and other combustion waste as grout inside a PVC shell to make utility transmission poles. Principal investigator: Paul Chugh, Dept. of Mining and Mineral Resources Engineering.

• Using scrubber sludge to make stain-resistant, nontoxic composite materials such as paperless structural wallboard, decorative tiles, countertops, and wood substitutes. Principal investigator: Vivak Malhotra, Dept. of Physics.

• Using FBC bottom ash to replace sand in pre-cast concrete piles and drilled shafts for deep building foundations. Principal investigator: Sanjeev Kumar, Dept. of Civil and Environmental Engineering.

• Using scrubber sludge and ash, with small amounts of lime and cement, to make a low-cost construction substitute for concrete pads in cattle feedlots. Principal investigator: Paul Chugh.

Supporters of these various projects have included the U.S. Department of Energy, the Illinois Clean Coal Institute, the Illinois Department of Commerce and Community Affairs (now called the Illinois Department of Commerce and Economic Opportunity), the Illinois Department of Transportation, and industry partners.

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