Oil shale ashes from the PAMA demonstration power plant in the Negev region of Israel are produced by fluidized bed combustion (700-850°C) under short residence time. The FED is organic-rich calcareous raw material rich in carbonate rather than clays. Thus it is important to ascertain whether the calcite in the ashes is original natural calcite from the raw material or the product of recarbonation of lime. Three groups of ashes from the power plant, Ash Cooler (AC), Fly Ash (FAS) and Boiler Bank (BB) were examined using XRD, FT-IR, SEM and isotope analysis methods. The recarbonated calcite is distinguished from the natural original by smaller crystal size, lower degree of crystallinity and the presence of impurities. High negative δ13C values in oil shale ashes are explained by assuming recarbonation of lime with CO2 originating from the combustion of the organic matter of the raw oil shale. Fly Ash, FAS, and BB, produced from organically-rich FED, contain more recarbonated calcite than bottom ash, AC. This observation can be explained by the larger grains of the AC, which do not reach the highest temperature area, and thus most of the original calcite does not decompose.
|Number of pages||10|
|Journal||Journal of Thermal Analysis and Calorimetry|
|State||Published - 2003|
Bibliographical noteFunding Information:
We thank PAMA, the Belfer Foundation and The Open University of Israel Research Fund for their financial support. We also thank Dr. T. Minster (Geological Survey of Israel) and A. Wohlfart and S. Cohen (PAMA) for their help in choosing the samples. We are grateful to Dr. R. Calvo and Dr. B. Shilman (Geological Survey of Israel) for carrying out the isotope analyses and M. Dvorachek for his help with the SEM work.
- Oil shale