Basic Blasting Technology

A complete glossary is included in the appendix of this course. However, since the next several sections will use many of the terms listed here in their technical senses, this section is provided as a quick review for those readers who are beginning the study of blasting, or for those who need a refresher.

Explosives are chemical mixtures or compounds that, when subjected to shock, impact, or heat, produce a rapid chemical reaction, accompanied by a shock wave in the product, that results in the sudden release of energy through the process of detonation. This sudden release of energy, mostly in the form of hot gas, when properly confined and initiated, can be used to perform mechanical work on the surrounding material. There are four basic components in commercial explosives: carbon, hydrogen, nitrogen, and oxygen. These components are combined so that the explosive mixtures are part oxidizer and part fuel or sensitizer (Figure 1).

Combustion is the exothermic chemical decomposition of a compound. It is a reaction between a fuel and an oxidizer.

Detonation occurs when the combustion of the explosive compound occurs more rapidly than the speed of sound. It propagates through the explosive material by a detonation, or shock wave. The speed of this wave through the surrounding rock will vary by explosive used, properties of the rock, and appropriate design of a blast.

Detonation Velocity is the speed that the detonation travels through the explosive once it has reached a steady state velocity.

Deflagration, or burning, occurs when the combustion of the explosive compound occurs at less than the speed of sound. It propagates through the explosive material through a flame front (heat transfer) with no shock wave.