Non-incineration Treatment to Reduce Benzene and V.O.C. Emissions from Green Sand Molding Systems
Cost-effective non-incineration techniques will significantly reduce volatile organic carbon (VOC) and benzene emissions from green sand foundries. Increasingly, green sand foundries must reduce benzene and VOC emissions during pouring, cooling, and shakeout. Conventional incineration systems to treat stack gases are costly to operate and difficult to maintain. Alternative pollution treatment methods are needed to comply with air quality requirements. Full-scale plant trials at green sand foundries have shown that simple, non-incineration advanced oxidation (AO) treatment systems or a combination of AO with underwater plasma (AO-UWAP) treatment can greatly reduce emissions. In AO and AO-UWAP treatment systems, wet collector sludge, or sand system baghouse dust is passed through a water slurry that has been preconditioned with ozone, hydrogen peroxide, and sonification/plasma treatment.
Pennsylvania State University and industry partners are evaluating the use of AO, and AO with an underwater plasma, as a green sand "additive". AO can be added to a foundry's green sand system wherever water is. In production, before water or black water slurries are added to the sand, they are treated with small amounts of AO combined with an ultrasonic treatment. It is believed that AO treatment cleans the clay, allowing them to be more easily activated. AO has the potential to activate the seacoal causing the mold to absorb VOCs. Hazardous pollutants and VOCs are oxidized within the green sand mold, and the amount of clay and seacoal required in the mold are reduced. Smoke and odor emitted during cooling and shakeout can be reduced significantly.