Paper No. 6
Presentation Time: 9:15 AM
GAS VENT MINERALOGY AND GEOCHEMISTRY: THE BURNING-CULM BANKS OF SOUTH AFRICA
STRACHER, Glenn Blair, Division of Science and Mathematics, East Georgia College, 131 College Circle, Swainsboro, GA 30401, PONE, J. Denis N., School of Geosciences, University of Witwatersrand, Private Bag X3, Johannesburg, 2050, South Africa, FINKELMAN, Robert B., U.S. Geological Survey, MS 956 National Center, Reston, VA 20192, ANNEGARN, Harold J., Department of Geography and Environmental Management, University of Johannesburg, P.O. Box 524, Auckland Park, Johannesburg, 2006, South Africa, MCCORMACK, John, Department of Geology, University of Nevada, Mackay School of Earth Sciences and Engineering, Reno, NV 89506, BLAKE, Donald R., Department of Chemistry, University of California, Irvine, 507 Rowland Hall, Irvine, CA 92697-2025 and SCHROEDER, Paul, Department of Geology, Univ of Georgia, 210 Field Street, Athens, GA 30602, stracher@ega.edu
Spontaneous combustion of coal as a consequence of opencast mining in South Africa, the world's fifth largest producer of hard coal, occurs frequently and is cause for concern, considering the volume of noxious fumes, dust, and particulate matter mobilized. In addition to consuming a valuable natural resource, gas exhaled from vents in culm banks and solid combustion by-products encrusting these vents may serve as vectors for the transmission of toxins to nearby floral and faunal habitats as well as to coal miners and people living in nearby communities. The toxins may be transmitted by atmospheric and water pollution, inhaled wind-blown dust particles, and food grown in soils polluted by derivatives of these solids.
Twelve assemblages of solids encrusting the outer perimeter of active gas vents and fissures, in addition to thirteen gas samples, were collected from burning-culm banks in the Witbank and Sasolburg coalfields northeast of Johannesburg, South Africa. In addition to bituminous coal, the culm banks consist of variable proportions of sandstone, mudstone, and regolith that may affect the composition of combustion by-products by interacting with the coal-fire gas prior to its exhalation at the surface.
Preliminary analyses reveal that the solids consist of a potentially toxic mixture of S, SxOy, SxOyNz, SxOyNzAlw, and SxNyClz compounds with crystalline habits that include cubes and rhombic dipyramids. Trace elements associated with some of the solids include As, Pb, Cu, Ge, and Hg. The gases are comprised of a complex mixture of hydrocarbons, halides, greenhouse gases, and toxic concentrations of CO, benzene, and toluene. The affects of numerous compounds in the gas on human health are unknown and merit investigation. Establishing criteria for toxicity is necessary for determining the need for environmental regulation.
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