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Filling Abandoned Mines with Fluidized Bed Combustion Ash Grout
Gray DD, Reddy TP, Black DC, Ziemkiewicz PF


Pages: 14    Published: Jan 1998


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Source: STP1331-EB


Abstract
The hydraulic backfilling of abandoned room and pillar coal mines with ash-based grout holds promise as an environmentally beneficial method of ash disposal, capable of preventing acid mine drainage and subsidence. For this scheme to be economically viable, the grout must be sufficiently flowable so that mines can be filled from a small number of boreholes. This paper describes the development and testing of a water-ash-bentonite grout using ash from a coal and gob burning atmospheric pressure fluidized bed combustor. Bentonite was needed to prevent settling which would limit the ability of the grout to spread. Laboratory techniques were devised to measure the rheological parameters of the grout. A static model was developed to predict the maximum distance of spread due to gravity. A field injection of 765 m of grout into an inactive mine panel showed that the grout flows well enough to make hydraulic backfilling feasible.


Keywords:
hydraulic backfilling, fluidized bed ash, grout, slurry, acid mine drainage, subsidence, yield stress fluid, flowable fil, CLSM

Paper ID: STP13071S
Committee/Subcommittee: D18.02
DOI: 10.1520/STP13071S
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