Low Density Ammonium Nitrate (LDAN) Porosity Control Agents
Ammonium nitrate (AN) continues to be widely used as a low cost blasting agent. It is inherently unstable and a total of five different crystalline states have been identified over cooling from the molten state to -16°C. The two states of concern are the alpha-rhombic and the beta-rhombic states in the temperature range most normally encountered under typical ambient conditions. These states can convert from one to the other upon temperature / pressure changes with resulting volume changes, which in turn can cause disruptions to the crystalline structure and lead to the production of dust / fines. Water is thought to “catalyze” these phase transitions.