Most Appalachian coal refuse materials contain significant amounts of pyritic sulfur and are likely to produce acid mine drainage (AMD). A column technique was designed and implemented to evaluate the effects of various AMD mitigation treatments including fly ash, topsoil, lime, and rock-P. Two types of fly ash were tested, one at four blending rates, the other at two rates. Conventional lime plus topsoil, lime without topsoil, topsoil only, topsoil with fly ash, rock-P plus topsoil, and rock-P plus fly ash were also evaluated and compared with pure refuse controls. The columns were dosed weekly with 2.5 cm of simulated acid rain, an amount equivalent to 152 cm (60 in.) rainfall per year and remained unsaturated at all times. The experiment was conducted for 40 weeks. The drainage from the unamended columns rapidly dropped to less than pH 2 with very high levels of Fe, Mn, B, S, and Al. Alkaline fly ash dramatically reduced drainage Fe concentrations as well as Mn, Al, Cu and S when compared to the untreated refuse. As expected, lime treatments also reduced the drainage Fe, Mn, Al, Cu and S concentrations. The rock-P treatments initially reduced Fe, Mn, Al and S, but eventually decreased in mitigation capability over time. Leachate B concentrations were initially high for some of the ash columns but eventually followed the same B elution trend as the untreated refuse. The combined treatments of phosphate/ash, ash/topsoil, and pure refuse with topsoil were intermediate between the pure ash treatments and unamended refuse in drainage quality. The data were analyzed to determine treatment effectiveness in reducing AMD, and to evaluate the overall replicability of the column design. All treatments varied greatly for the first 5 weeks as the initial flush of salts from the materials occurred, but most treatments stabilized by week 6 with relatively low within treatment variability. The high ash blending rates remained alkaline for extended periods of time and stabilized pyrite while neutralizing any acidity. The rock-P treatment appears to have bound free Fe and other elements released from pyrite oxidation but did not prevent acidification. Long term analysis may prove fly ash to be a viable alternative to conventional topsoiling/lime treatments to ameliorate AMD if adequate alkalinity is present in the ash/refuse mixture. If fly ash alkalinity is inadequate to balance potential acidity, accelerated leaching of ash bound metals may occur. / M.S.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/106874 |
| Date | January 1993 |
| Creators | Jackson, Meral Lyn |
| Contributors | Crop and Soil Environmental Sciences |
| Publisher | Virginia Polytechnic Institute and State University |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | xxi, 182 leaves, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 29323457 |
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