Filling abandoned mines with fluidized bed combustion ash grout

摘要

The hydraulic backfilling of abandoned room andpillar coal mines with ash-based grout can be anenvironmentally beneficial method of ash disposal, capable ofpreventing acid mine drainage and subsidence. For this schemeto be economically viable, the grout must be sufficientlyflowable so that mines can be filled from a small number ofboreholes. This paper describes the development and testing of awater-ash-bentonite grout using ash from a coal and gob burningatmospheric pressure fluidized bed combustor. Bentonite wasneeded to prevent settling which would limit the ability of thegrout to spread. Laboratory techniques were devised to measurethe rheological parameters of the grout. A static model wasdeveloped to predict the maximum distance of spread due togravity. A field injection of 765 m3 of grout into an inactivemine panel showed that the grout flows well enough to makehydraulic backfilling feasible.