entech. WKP Magazine Explosion Simulation – Gas Dispersal Study P a g e | 6 3 PRIMARY VENTILATION LAYOUT 3.1 VENTILATION CONNECTIONS TO SURFACE The locational map Figure 3-1, for WKP’s surface connections to underground workings was provided by WKP. These surface connections are the focus for assessing the hazards to the local surrounds. All surface connections are vertical shafts except for the two access portals Plant and Willows. Figure 3-1 – WKP surface connections. Plant and Willows portals are the vehicle access points to the mine, with Plant being ~10 km from the production area. Rise 1 is the proposed fresh air intake and Rise 2 the exhaust shaft. For the sake of this study, Rise 3 and Willows Rise will be considered closed to surface. 3.2 VENTILATION PATH FOR MAGAZINE EXPLOSION GASES Under mechanical ventilation Rise 2 return air rise (RAR) is the sole exit point for blast contaminants. Due to the location of the bulk explosive storage facility, being 380 m below surface, no flow reversal because of the blast will occur at any of the other surface connections. If fans switch off due to power failure, then the natural ventilation flow within the mine may see other connections dispersing contaminants such as Rise 1 fresh air rise (FAR) and the two haulage portals Plant and Willows. The modelling suggests that WKP will be highly variable during natural ventilation flow. This means that changes in atmospheric conditions could switch the blast fume path between the open connections, presenting two scenarios for the exhaust path. Scenario 1 sees the fresh air entering the Plant and Willows portals with contaminated air exiting via Rise 1. Scenario 2 sees this in reverse, with Rise 1 down casting fresh air and contaminated air exiting via the Plant and Willows portals. This variability suggests that with only minor changes in barometric pressures, blast fumes could be trapped underground for protracted periods until mechanical ventilation is restored.
RkJQdWJsaXNoZXIy MjE2NDg3