Over the past 20 years within Australia, there have been a number of incidents at mine sites where ammonium nitrate-based explosives have reacted with certain rock types containing sulfide minerals. These rocks have commonly been referred to as reactive ground'. These reactions have frequently led to fires (particularly in ground susceptible to spontaneous combustion) or premature detonation of the ammonium nitrate-based explosives. Clearly, this introduces an element of risk when using ammonium nitrate-based explosives in these areas._x000D_
Dyno Nobel has been proactive in developing ammonium nitrate-based explosive products that can be used in these types of reactive ground' environments that minimise the risk of premature detonations occurring._x000D_
A system for assessing reactivity' of sulfide containing rocks has been developed that can be used in the field. Previous literature has been reviewed, identifying Differential Thermal Analysis (DTA) as the most common method for determining the reactivity' of the ground. In the present investigation, DTA has been rejected as a suitable technique for determining ground reactivity, since it measures thermal reactions at higher temperatures over short time periods, conditions that are unlike those in the field. For example, ground at ambient temperature has been found to react with ammonium nitrate-based explosives over long time periods, reactions that are unable to be evaluated using DTA. Other more suitable techniques have been developed to monitor rock conditions that can be measured in the field and give a good indication of potential ground reactivity' with ammonium nitrate-based explosives._x000D_
Dyno Nobel is currently investigating the reaction mechanisms of spontaneous combustion in reactive ground, the decomposition mechanisms of ammonium nitrate and the role of inhibitors in ammonium nitrate-based explosives. Once complete, this fundamental research will lead to the further development of even lower risk ammonium nitrate-based explosive products for use in reactive grounds' in a variety of mine environments.