Figure 9. Temperature exceeding 700°C [1292°F] on the data logger. Figure 10. Reactive zone mapping. showed a clear indication of the reactive process taking place. South Africa National Standard (SANS) standard requires detonators to function nominally up to 85°C [185°F] and it is recognized that once this temperature is exceeded the possibility for an unplanned detonation increases. Laboratory Report Ground samples were collected from the reactive areas and sent for testing at the Losberg Laboratory. Extreme reactive ground reactions were observed in two samples that had been loaded with uninhibited bulk ammonium nitrate explosives. The sample marked as Exploded Hole also showed a reaction indicating reactive ground. See figure 7 - Ground sampling map. Upon initial inspection of the samples received, flakes of pyrite were visible in the samples with some larger pieces of pyrite as well. See figure 8 - Visible pyrite in sample. Table 1 shows the degree of reaction with the uninhibited emulsion and drill cutting samples. The temperature of the samples was monitored during testing with a temperature data logger. Temperatures exceeding 700°C [1,292°F] were measured within an hour of mixing the samples. See figure 9 - Extreme test sample temperatures. The same tests were conducted using a urea inhibited bulk emulsion (INNOVEXTM act, nor was there a measured temperature spike. Work in Progress Ongoing characterization work to understand the reactive ground at the zinc mine is being done. As mining progresses, drill samples are analyzed and tested to build and create reactive zone maps of the geology. This is used to mark out potential reactive ground areas in the current and future mining blocks. See figure 10 - Reactive ground mapping. These samples are also sent for testing at the Losberg Laboratory to confirm the use of urea inhibited emulsion is effective against ground reactivity. The PVJ drill chip sampling method is also being introduced to this site. This simple spot check method is performed on the bench and no samples need to be taken and sent for analysis. The drill chip sampling method consists of sampling the drill cuttings from approximately 25% of the blast holes as RG). The inhibited emulsion did not reMay/June 2022 The Journal of Explosives Engineering 11