Blasting

Blasting is the controlled use of explosives to fracture rock or other hard materials. It is employed in mining, quarrying, construction, and civil engineering to create access, reduce rock mass, or loosen material for excavation. Blasting programs are designed to achieve a balance between productivity, fragmentation, and safety.

Charges are placed in drilled holes or boreholes and detonated in sequences. Common explosive systems include ammonium nitrate fuel oil (ANFO), emulsions and gels; ancient dynamite is largely historical. Initiation can be electric, non-electric (such as detonating cord), or electronic to control timing. Design variables include burden (rock in front of the borehole), spacing between holes, stemming to confine the charge, and delays between circuits to control vibration and fragmentation.

Surface blasting is used in open-pit operations; underground blasting is used in tunnels and stops. Blasting aims to optimize fragmentation, reduce flyrock risk, control ground vibration, and minimize dust and air blast. Pre-blast surveys, blast mats, and berms are among mitigation measures employed to protect workers and nearby structures.

Safety and regulation: Blasting is subject to licensing, training, and oversight by mining or blasting authorities. Procedures include pre-blast risk assessments, blast design reviews, and real-time monitoring of vibration and air blast. Observers establish danger zones and restrict access during detonations.

Environmental considerations include ground vibration, flyrock, noise, dust, and fumes. Advances in electronic timing, data logging, and software help improve precision and reduce impacts. The history of blasting traces to the 19th century with dynamite developed by Alfred Nobel, evolving into modern controlled blasting methods.