B3 Representative continuous emission rate Dispersion modelling requires the input of a continuous emission rate of each contaminant. The concentration of each contaminant (and consequently the emission rate) varies substantially over 15 minutes and 40 seconds (or 940 seconds) before the detonation products are considered fully exhausted. In order to find a representative continuous emission rate, the total mass released of each contaminant was calculated and averaged over the release time for a conservative emission rate as follows: The emission concentration profile in milligrams per cubic metre (mg/m3) was converted to a mass at each time interval (one second) using the volumetric flow rate for Site 5 – Rise #2 (387 m3/s). = 1 C 0 x 0 V 0 Where: C is the instantaneous predicted concentration at the mine conditions in mg/m3, and V is the volumetric flow rate from the surface connection in m3/s and The mass is calculated in grams. Each one-second mass value was summed together to predict the total mass emission over the duration of the release, shown inAppendix B Table 2 below. The total mass was then divided over the total number of seconds to provide a representative continuous emission rate in grams per second for the period. This continuous emission rate was used in the modelling, providing a conservative result in which 3 - 4 times the amount of contaminant is emitted over an hour. Appendix B Table 2: Calculation of continuous emission rate Contaminant CO NOX NH3 Mass emitted over 940 seconds (g) 33,077 4,293 1,401 Corresponding continuous emission rate (g/s) 35.2 4.6 1.5
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