How did ammonium nitrate make dynamite safer and less expensive?

The substitution of ammonium nitrate for a portion of the nitroglycerin in dynamite formulations significantly improved both safety and cost-efficiency.12

Safety Improvements
Ammonium nitrate is characterized by a low explosion temperature. When used in explosives, it is often combined with cooling agents like sodium chloride or ammonium chloride. These additives prevent the heat generated during an explosion from igniting flammable underground gases, such as methane, or coal dust, thereby reducing the risk of secondary fires or explosions in mining environments.1

Cost Efficiency
The cost of dynamite was reduced by replacing expensive nitroglycerin with more affordable ammonium nitrate, particularly as synthetic ammonia production became cheaper due to manufacturing advancements and the use of natural gas as a raw material. Manufacturers developed low-density ammonia dynamites by diluting the mixture with inexpensive, low-density ingredients like bagasse. This allowed for the creation of products that provided the same blasting action as traditional, higher-cost dynamites while using a smaller amount of nitroglycerin.1