(633d) Effect of Calcium Halide Salt Addition on the Fate of Rare Earth Compounds during Coal Combustion Process

Burgess, W. A., National Energy Technology Laboratory
Granite, E. J., United States Department of Energy
Roth, E., DOE National Energy Technology Laboratory
Keller, M. J., US DOE/NETL
Howard, B. H., National Energy Technology Laboratory
Lekse, J. W., National Energy Technology Laboratory
Calcium halides are sometimes added to coal prior to combustion to facilitate the removal of mercury from the flue gas. To assess the impact of these additives on the fate of the rare earth compounds (typically phosphates in the feed coal) through the power plant, it is convenient to study model systems of rare earth phosphate plus a calcium halide. In this work, the kinetics of the high-temperature roasting of lanthanum phosphate with calcium chloride and calcium bromide were studied at temperatures up to 1000° C. XRD was used to elucidate the reaction pathways observed both in the presence of air and in an oxygen-free environment. Apparent activation energy and Arrhenius pre-factor for each reaction were determined from TGA experiments.