Loading and Blasting Drilled
Holes

Once the holes have been drilled, a blasting crew loads the holes with explosives. Nitroglycerine dynamites and ammonium-nitrate blasting agents are the common types of explosive. A mixture of fertilizer (ammonium nitrate) and fuel oil, called ANFO (an acronym for ammonium nitrate and fuel oil), is in common use in mining. It is set off or initiated by a high-explosive blasting cap and/or primer. Machines for loading explosives range from small portable ANFO loaders to specially designed mobile vehicles with large hoppers for transporting and loading bulk explosives pneumatically.

Holes are loaded so that each charge is fired in a designed sequence. This is important in order to obtain the desired break.

Large blasts or charges are usually set off electrically from surface once all underground workers are out of the mine, usually at the end of a work shift. This is done not only to ensure safety but also to allow the dust and fumes caused by a blast to be dissipated by the ventilation system before the next shift goes under ground.