| Processing Plant Emissions | WNP Processing Plant Air Discharge Assessment | 4397169-66885702-113 | 16/06/2022 | 8 Sensitivity: General Table 2-8. Comparison of 2009 and 2021 furnace emission rates. Metal 2009 Discharge Rate (g/h) 2021 Discharge Rate (g/h) Arsenic 0.0004 0.002 Cadmium 0.0020 0.0979 Chromium 0.0053 0.0078 Copper Not measured 0.063 Manganese 0.0059 0.0046 Nickle 0.053 0.0008 Lead 0.0077 0.124 Selenium 0.365 0.494 The metal content of the mined ore will vary. Consequently, metal emission rates can also expect to vary when different ore types are processed. Table 2-9 summarises the average metal content of the MUG, GOP and WUG ore types. Except for arsenic, the metal content of the MUG ore is on average higher, or similar to the metal content of the GOP and WUG ores. Although, the average concentration of arsenic in the GOP and WUG ores are approximately 12.7 - 14.1 times higher than the arsenic concentration in the MUG. Table 2-9. Summary of the average metal concentrations (ppm) in MUG, GOP and WUG ores. MUG ore (ppm) GOP ore (ppm) WUG ore (ppm) Arsenic 19.6 275 250 Cadmium 0.1 0.2 0.1 Chromium 75.8 43.7 23.4 Copper 392 16.3 25.4 Manganese 1030 77.1 143.9 Nickle 34.3 12.8 2 Lead 14 7 7.7 Selenium 2 3.6 2.6 Based on the comparison between the emission rate observed in 2009 and 2021 and relative metal content of the MUG, GOP and WUG ores, the results of the 2021 testing programme are expected to provide a broad indication of emissions during the WNP project. The testing to date indicates that higher arsenic emissions could be occur during the processing of the GOP and WUG ore but emissions of copper and manganese are expected to be lower. However, some variations of the emissions are expected to occur in response to natural variation in the ore’s metal content. This shown by the difference observed between the reported 2009 and 2021 emission rates. It is therefore recommended that emission testing is conducted when MUG, GOP and WUG is processed to better characterise this variation (and confirm compliance with the ambient guideline levels). However, the primary concern is associated with long term exposures to metal. Therefore, the short-term variations in mercury emission rate are less important. Annual metal emission rates would still be expected to increase with the proposed increase in the volume of ore processed.
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