Energy & Fuels 1988,2, 13-17 consumed. Apparently the crystalline feldspars do not participate since their diffraction peaks do not diminish until temperatures exceed 1250 K. In fact, a t 1173 K or less, these peaks were observed to increase, probably due to crystallization. It is also interesting that while Campbell3 hypothesized that calcium silicates formed prior to calcium-magnesium silicates, we did not detect calcium silicates until a temperature of 1173 K. Since the low-
13
temperature MgO product is amorphous, it is likely that its small grain size makes for a very reactive species that readily combines with small-grained silicon to form akermanite and augite. To this extent, our results corroborate the conclusions reached by Park et a1.* Registry No. CaC03,471-34-1;Ca2Si04,10034-77-2;Ca2MgSi207,13573-15-4; ferroan dolomite, 99401-51-1.
Detection of Carbonyl Functionality of Oxidized, Vacuum-Dried Coals by Photoacoustic Infrared Fourier Transform (PAIFT) Spectroscopy: Correlations with Added Oxygen and with Plastic Properties' Brian M. Lynch,* Lai-Im Lancaster, and J. Anthony MacPhee Department of Chemistry, St. Francis Xavier University, Antigonish, Nova Scotia B2G 1 CO, Canada, and Energy Research Laboratories, Canada Centre for Mineral and Energy Technology, Ottawa, Ontario K1A OG1, Canada Received June 17, 1987. Revised Manuscript Received September 9,1987
Photoacoustic infrared Fourier transform (PAIFT) spectroscopy of powdered oxidized bituminous coals reveals distinguishable and specific carbonyl-type functionalities, suggested as arising from precursor peroxide species by thermal decompositions accompanying standard vacuum-drying procedures. The behavior patterns of a suite of Canadian and U.S.A. coals of daf carbon content from 84% to 90%, subjected to progressive oxidations with air at 55 "C and 9 Mpa, differ in the distribution and rate of generation of the various types of carbonyl peaks. Peak intensities and integrated areas of the carbonyl peaks in the oxidized coals are proportionate to increased bulk oxygen content, and there are quantitative associations between the level of carbonyl content indicated by PAIFT spectra and plastic properties (Gieseler fluidity, percent dilatation, and melting range) of the coals. The rates of generation of added ketonic carbonyl entities are functionally dependent on the oxygen content of the fresh coals.
Introduction Oxidation of bituminous coals by natural in situ processes (weathering), during storage after mining, or by heating to moderate temperaturea (
