Superfund Innovative Technology Evaluation (SITE)
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|Demonstration Bulletin Minergy
Glass Furnace Technology Minergy Corporation
The Glass Furnace Technology (GFT) was developed by Minergy Corporation (Minergy), of Waukesha, Wisconsin. Minergy originally developed vitrification technologies to process paper mill sludge into glass aggregate that could be sold as a commercial product. Minergy modified a standard glass furnace to melt and treat river sediment containing polychlorinated biphenyls (PCBs). The technology was evaluated during a U.S. Environmental Protection Agency Superfund Innovative Technology Evaluation (SITE) Program demonstration at the Minergy facility in Winneconne, Wisconsin, in August 2001. The SITE program evaluated the technology's ability to treat sediment containing PCBs and metals to form a product with beneficial reuse. Because the GFT melter requires the river sediment to be greater than 90 percent solids prior to loading it into the melter, the SITE program also evaluated a bench-scale dryer technology as a secondary activity. The sediment for this evaluation was dredged from the Lower Fox River, dewatered, and filter-pressed. The PCB concentration of sediment fed into the GFT unit ranged up to 36 parts per million (ppm) by weight.
In the GFT process, dried sediment is fed into the GFT hopper above the feeder mechanism. The feeder conveys the sediment continuously into the main section of the melter. At the furnace temperature of 2,900 Fahrenheit, the sediment's organic portion is destroyed, and the inorganic portion does not burn, but melts, forming molten glass. The molten glass flows through the furnace into the forehearth, where it is stabilized. That glass then flows through an opening at the end of the forehearth and drops into a water-filled quench tank. Exhaust gases flow from the furnace through a flue. For the demonstration, air-sampling equipment extracted glass-furnace emissions from this flue for laboratory analyses.
Minergy claims that the GFT process offers advantages over incineration and other vitrification technologies. An incinerator would require large quantities of fuel for treatment of low-organic-content sediments. In addition, typical waste incineration generates large amounts of ash that require landfilling. Unlike other vitrification technologies, GFT is designed to melt materials that have no fuel value. Other vitrification systems typically re-quire very high energy consumption. GFT is based on commercial glass-making technology, which operates in a more energy efficient manner. The GFT uses oxy-fuel burners, combining natural gas and purified oxygen to create intense flames above the glass pool.