1952 Figure 115: Isothermal Reactive Ground Test Apparatus with inset showing detail of aluminium heating block All isothermal testing was done at Orica’s Kurri Kurri Technical Centre using the procedure described in the AEISG isothermal reactive ground test (AEISG, 2020). Two sample types were used in the study 1) a reactive ground standard developed in-house to provide consistent reproducible results across experiments and 2) reactive samples from mines that consistently displayed reactivity to AN in the absence of the above-described inhibition components in the explosive. In the standard procedure, a crushed reactive rock sample was mixed with an inhibited bulk explosive and maintained at 55 °C in a dry block heater for the duration of the test (AEISG, 2020). A thermocouple monitored the sample’s temperature for any exothermic peak greater than 2 oC from baseline, which indicates the onset of the AN-sulphide reaction. If no reaction occurs for the duration of the test, the explosive was deemed compatible (safe to sleep for the corresponding field sleep time). Following industry guidelines, the test duration was typically set to safety buffer included 4 times the desired field sleep time for up to 7-day sleep times. For example, a 7-day sleep time requires a 28-day test with no reaction.
RkJQdWJsaXNoZXIy MTM0Mzk2