Secondary Aluminum Processing Waste: Baghouse Dust Characterization and Reactivity
Citation:
Tolaymat, T. AND X. Huang. Secondary Aluminum Processing Waste: Baghouse Dust Characterization and Reactivity. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-15/203, 2015.
Impact/Purpose:
Given the potential concern associated with the reactivity of BHD in a landfill environment, the U.S. EPA initiated a collaborative research effort with the Aluminum Association and the Environmental Research and Education Foundation to characterize BHD waste material and investigate its reactivity under controlled conditions. This report presents the first systematic study on the characteristics and reactivity of BHD derived from operating SAP facilities in the U.S. The specific objectives of the study were to: • Identify and characterize the metal constituents in BHD • Investigate the leaching behavior of metals from BHD following its reaction with water • Identify the dominant crystalline mineral phases in BHD • Evaluate factors that impact the reactivity of BHD • Evaluate BHD reactivity with water
Description:
Results presented in this document are of particular importance when trying to understand concerns associated with the disposal of BHD in MSW landfills. The MSW decomposition process is exothermic, creating landfill temperatures that are typically greater than 37° C with the possibility of reaching 50° C or more. The elevated temperatures present in most MSW landfills can be conducive to and could initiate BHD reactions that otherwise may not take place. Furthermore, elevated temperatures can increase the rate of a BHD reaction, and thus further propagate it. Even outside of MSW landfills, once a BHD reaction starts, it may self-propagate and increase the rate at which the reaction occurs. The results presented herein suggest that higher environmental temperatures tend to intensify a BHD reaction. As stated earlier, this is of particular significance for the disposal of BHD. Depending on their design and capacity, MSW landfills tend to be well-insulated and operate at elevated temperatures. When these conditions exist, the reaction of BHD with liquids tends to become more problematic as the elevated temperatures may initiate the BHD reaction with water while the insulating properties of the landfill may intensify the reaction and magnify the impact of the reaction.