How does blasting break rock into pieces that can be loaded and hauled?

In the mining industry, blasting is the process of reducing solid rock into fragments using explosives to facilitate loading and hauling. The process typically follows these steps:1

• Drilling: Blastholes are drilled into the rock face in a specific pattern. In underground mining, these holes are often drilled using drill jumbos, while surface mining may involve vertical holes drilled from the surface.23
• Charging: The holes are filled with explosives, such as ANFO (a mixture of ammonium nitrate and fuel oil), which are either pumped, blown, or inserted as cartridges.23
• Detonation: When the charges are fired—often in a predetermined sequence using detonators with millisecond delays—the chemical energy is released as high-pressure gas. This pressure shatters the rock immediately surrounding the hole and induces stresses that cause cracks to propagate through the rock mass.13
• Fragmentation: The gas pressure forces the rock to yield and move toward an exposed face or into designated expansion space, breaking it into manageable pieces.13

Once the rock is fragmented, it is cleared away by loading machines, such as LHD units, and transported for further processing.13