Sullivan Mine Fatalities Incident: Numerical Modeling of GasTransport and Reversal in Gas Flow Directions

摘要

The Sullivan Mine No. 1 Shaft Waste Rock Dump is located on a natural slope andcovered by till. The outflow of oxygen-deficient gas through a leachate drainage pipe inan enclosure at the base of the dump resulted in four fatalities in May 2006. A numericalmodel was developed to understand controls on gas flow, which was found to be relatedto the relative buoyancy of the dump gas phase compared to atmospheric air. Changes inatmospheric air density are caused by atmospheric temperature variations, whereas thedump gas phase density is fixed by the steady internal dump temperature. Whenatmospheric temperature is lower than the internal dump temperature, atmospheric airdensity is higher than dump gas density, inducing upward dump gas flow and air entry inthe pipe. Instead, downward dump gas flow occurs and exits the pipe when highatmospheric temperature leads to an air density lower than dump gas density. A similargas flow behavior would still occur without the pipe or without the till cover, indicatingthat the observed gas flow conditions could be present in other waste rock dumps.