Abstract |
The paper summarizes ongoing research efforts at the National Risk Management Research Laboratory of the U.S. Environmental Protection Agency examining (high temperature) metal behavior within combustion environments. The partitioning of non-volatile (Cr and Ni), semi-volatile (Cd and Pb), and volatile (Hg) metals in combustion systems was investigated theoretically and experimentally. Theoretical predictions were based on chemical equilibrium and suggested that such calculations can be useful in predicting relative volatility and speciation trends, and to direct experimental efforts. Equilibrium studies employing a 59 kW laboratory scale combustor examined the behavior (volatility, particle size, and speciation) of metal vapors and particles poduced by aqueous metal solutions sprayed through a swirling natural gas diffusion flame. These experiments were designed to study metal transformation mechanisms in a relatively simple combustion environment without the complex effects of additional species. Further experiments examined the potential use of common inorganic sorbents (kaolinite, bauxite, and hydrated lime) to adsorb metal vapor, offering a potential means of metal emissions control. |