8 Tonkin & Taylor Ltd Wharekirauponga Underground Mine – unplanned detonation air quality assessment Oceana Gold New Zealand Limited June 2022 Job No: 1015212.2000 vRev0 D R A F T 3.3 Discharge location and parameters 3.3.1 Stack discharge parameters The physical parameters of the vent discharges from the Site 5 (Rise #2) vent for Scenario 1 are summarised inTable 3.2. The derivation of the parameters is based on the following: Physical stack dimensions provided by OGNZL. Mine ventilation simulation provided by Entech. Table 3.2: Summary of modelled vent discharge parameters Stack ID Stack name Stack height (m) Stack orientation Exit diameter (m) Vent exhaust flowrate (m3/s) Vent exit velocity (m/s) Exit temperature (°C/°K) Site 5 Rise #2 7.8 Vertical 5.5 387 16.3 21.4 / 294.4 3.3.2 Emission rates The emission profile for the mechanically ventilated scenario shows that all the contaminants are exhausted from the return air rise (Site 5) in under 20 minutes from the detonation. This will provide the highest concentration of contaminants in the gas stream. The modelled emission rates for the mechanically ventilated scenario are provided inTable 3.3 below. These rates were determined in accordance with the calculations set out inAppendix B. Table 3.3: Modelled emission rate Source ID Source name CO (g/s) NOX (g/s) NH3 (g/s) Site 5 Rise #2 35.2 4.6 1.5 While some of the oxides of nitrogen produced in the detonation are expected to be emitted as nitric oxide, for the purpose of a conservative screening assessment it has been assumed that all NOX is released as NO2 from the source.
RkJQdWJsaXNoZXIy MjE2NDg3