Leaching Behavior of Coal Combustion Products and the Environmental Implication in Road Construction.

摘要

Leaching of trace elements may raise environmental concerns when using coal fly ash in road construction. The U.S. Environmental Protection Agency is in the process of creating the first national rule on coal ash management, including beneficial use. Meanwhile, driven by tightening emission regulations, technological evolution at the coal energy industry continuously generates new types of coal fly ashes with unknown characteristics. These changing landscapes may impact the coal ash utilization options in the construction industry. To minimize the possible adverse environmental impact in utilizing coal ash for road construction, it is important to evaluate the characteristics of fly ashes generated from plants that employ new air emission control technologies, to determine the leachability of trace contaminants, and to find effective methods for remediating inorganic contaminants in fly ash when necessary. This project assessed the physical and chemical characteristics of fly ashes produced from trona injection plants (used for SO2 emission control), and investigated the leaching of a group of concerned inorganic contaminants from these fly ashes. A protocol was developed to quantify the availability and stability of As and Se in raw bituminous fly ash under various field conditions. The effectiveness of ethylenediaminetetraacetate (EDTA)-washing in remediating fly ash was also studied. This report presents the results of this project in the format of four journal manuscripts, which are in the process being submitted for peer review and publication.