Geochemical Evolution of a SurfaceMine Lake with Alkaline Ash Addition: Field Observations vs.Laboratory Predictions |
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Authors: | Caroline?M.?Loop mailto:loop@psu.edu" title=" loop@psu.edu" itemprop=" email" data-track=" click" data-track-action=" Email author" data-track-label=" " >Email author,Barry?E.?Scheetz,William?B.?White |
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Affiliation: | (1) Dept of Geosciences and Materials Research Inst, The Pennsylvania State Univ, University Park, PA, USA;(2) Dept of Mech and Nuclear Eng and Materials Research Inst, The Pennsylvania State Univ, University Park, PA, USA |
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Abstract: | ![]() Abstract. In the Eastern Middle Anthracite field of Pennsylvania, aformerly acidic (pH = 3.6) surface mine lake (initiallyapproximately 45,000m3 in volume) isbeing reclaimed using fluidized bed combustor (FBC) ash. The pHof the water in the pit dramatically increased when the alkalineash was added. The pH of the water is now well buffered, and hasnot dropped below a value of 11.0 since March 2000. Analysis ofdata from samples collected over the past six years indicatethat the lake s alkalinity is controlled by carbonate, silicate,and hydroxide reactions. The relative importance of thesefactors varies with ash input, and can be determined in apredictable fashion. Laboratory tests determined that the massof CaO was more significant than the particle surface area onthe pH of the solution. Using only alkaline material, thetransition between caustic and carbonate alkalinity wasapparent, though this did not account for interaction withsilicate minerals, which should be considered when usingalkaline ash for reclamation. Field data indicate that withtime, the pH will again decrease but will be buffered by calcitepresent on both the upper walls of the mine pool and withinpores of the FBC ash. Less than 1% of the ash is currently usedto increase the pH and alkalinity, so a large reserve exists forlong term buffering capacity. |
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Keywords: | : Alkaline anthracite co-generation fly ash reclamation |
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