Sulfate Production Rates in Pyritic Pennsylvanian-Aged Shales1
- Calvin C. Ainsworth and
- R. W. Blanchar2
An incubation study was initiated to measure sulfate production within various shale layers of coal overburden. Samples of air-dried, crushed, and sieved shale were adjusted to −33 kPa moisture potential and incubated with and without inoculation by a Thiobacillus thiooxidans, ferrooxidans, and thioparus culture at 298 K in either air or CO2-enriched air. Samples were removed periodically during a 28-d incubation and analyzed for SO42-. Ninety percent of the variation in rate of pyrite oxidation was due to differences in the shale layers and there were no significant differences measured due to addition of bacteria or increased CO2 level. A zero-order rate of SO42- production with respect to SO42- level was observed in all layers. The rate constants varied from 12 to 182 mg S/kg shale per day for the various shale layers. The rate of pyrite oxidation was higher in samples with pH values near 4 than those with pH values near 6.5.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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