  This work is concerned with the Ca transformations during the pyrolysis of
Ca(OH)2 or CaCO3-added coals. Ca K-edge X-ray absorption near edge structure
(XANES) spectroscopy was applied to determine the forms of Ca in chars prepared
from the pyrolysis of Ca-added coal. Results showed that Ca(OH)2 and CaSO4
existed in both the Ca(OH)2-added chars and the CaCO3-added chars, while CaS
and CaO only existed in the chars prepared from the Ca(OH)2-added coal.
Moreover, it was found that carboxyl Ca was formed during pyrolysis for either
the Ca(OH)2-added coal or the CaCO3-added coals.
