Handbook for Methane Control in Mining - AMMSA

181INDEXAAbnormally gassy faces...........................................46Air velocity, effect of.........................................12, 17Anomalous methane emissions................................98Anti-ignition back spray ..........................................59Auger mining – See Highwall mining ...................135Auxiliary air movers................................................18Auxiliary fans ..........................................................18BBarometric pressure, shaft sealing.........................133Bit wear, ignitions....................................................49Bleeder splits .....................................................68–69Bleeder systems .................................................63–76additional air splits........................................68–69designing ............................................................64evaluating ...........................................................71examining ...........................................................69flow-through .......................................................65maintaining ........................................................69water drainage.....................................................69wrap-around........................................................64Blowers..................................................................107Blowing ventilation .................................................41Bolter faces..............................................................48Boreholes, degascross-measure .....................................................86horizontal............................................................83short-radius.........................................................85vertical ................................................................84Bump test, methane detectors..................................31CCalibration of catalytic detectors, different gases....33Catalytic heat of combustion sensors.......................13Clastic dikes...........................................................104Clay veins ..............................................................104Cleats .....................................................................103Coal dust and methane mixtures, explosibility......149Coal dust explosions..............................................147Coal seam degasificationeconomics ...........................................................93thresholds............................................................80Coal silos .......................................................141–146closed-top silos .................................................143explosion in British Columbia, Canada ............144load-out areas....................................................143reclaiming areas................................................143Crosscuts, ventilation...............................................45Cross-measure boreholes.........................................86DDegasification of coal seams .............................77–96economics of.......................................................93horizontal boreholes ...........................................83methane capture ratios ..................................83–90vertical frac wells................................................84Diffuser fans ............................................................46Dikes......................................................................104Dilution capacity of bleeder systems.......................75Dilution of methane ..................................................3Direct method ..................................................10, 114District recirculation................................................16Domal salt mines ...................................................154Drainage of methane................................................83Dust collectors...................................................41, 45Dust explosions .....................................................147Dust scrubber recirculation......................................15Dust scrubbers ...................................................41, 45EEconomics of coal seam degasification...................93Eddy zones, longwall.........................................56, 58Effective inert, in explosibility diagram ....................4Emission peaks ........................................................37Emission rate .............................................................9Excess nitrogen, in explosibility diagram..................4Exhaust ventilation ..................................................45Explosibilityinert gases, effect on .............................................4pressure, effect on.................................................5temperature, effect on ...........................................5Explosibility diagram ................................................5Explosibility of gas mixtures.....................................3Explosions ...............................................................78Explosive range .........................................................3Extensible curtain systems.......................................39FFan spray system .....................................................40Faults .............................................................100–104large-scale.........................................................101normal...............................................................102reverse...............................................................103small-scale ........................................................101Filling shafts at closed mines.................................132Forecasting methane emissions .........................9, 119Frac wells.................................................................84Fractures ................................................................103Frictional ignitions.............................................48, 59Froude number.........................................................17