FE-57 MOSSBAUER SPECTROSCOPIC INVESTIGATION OF LOW-IRON COALS AND THEIR FLY-ASH

Trends in the speciation of iron and sulfur in high iron/sulfur coals are well established. Less is known concerning iron and sulfur speciat ion in low sulfur coals such as those investigated in this study. Low sulfur coals and their flyash from Thunder Bay, Ontario, Canada and At ikokan, West Virginia, U.S.A. have been investigated by means of Fe-57 Mossbauer spectroscopy, X-ray diffraction and X-ray fluorescence. Vir gin coals, containing approximately 0.1% Fe, exhibited Mossbauer spect ra too low in intensity to characterize the phases present. The flyash exhibited well-resolved, simple doublets with Delta E-Q=1.16 mm s(-1) (Canada) and 1.26 mm s(-1) (U.S.A.) and isomer shift values (w.r.t. F e) of 0.22 mm s(-1) and 0.23 mm s(-1) respectively, characteristic of Fe3+. The linewidths of similar to 0.80 mm s(-1) are unusually large. Treatment of the flyash with cold, hydrofluoric acid resulted in a sam ple that exhibited very Little absorption in its Fe-57 Mossbauer spect rum. This result, in conjunction with the linewidths, indicates that t he Fe is present in the flyash mainly as a silicate glass.