Blasting is the process of breaking of bulk rock masses into loose forms, using explosive compounds. Here, the primary role is played by the explosives. The explosives are the substances or devices used in blasting. The explosives are used to produce a volume of rapidly expanding gas that exerts sudden pressure on its surroundings and break the mass into pieces But when it comes to underground coal mining, all coal seams are considered gassy and the degree of the gas present may vary from I to III. Then only permitted explosive & approved detonators are to be used.
Concepts of solid off Blasting;-Freedom to Move : In situ Coal needs free passage to move out during blasting, i.e. Free face to be created by Creating wedge opening by drilling and blasting a few additional holes preferably Solid Blasting.