History of Blasting

Explosives have been used in mining and construction applications since 1627, the date of the first recorded use of black powder for rock blasting in a gold mine in Hungary. Before this, black powder was used primarily for military applications, signals and fireworks. The first recorded civil structure using black powder was the construction of the Malpas Tunnel of the Canal du Midi in France in 1679. Black powder remained in common use for construction and mining from the 1600s until the invention and application of nitroglycerine dynamite by Alfred Nobel in 1866. For much of that time, the composition of black powder remained unchanged with constituents of 75% saltpeter (potassium nitrate), 15% charcoal and 10% sulfur. Then in 1858, an American industrialist, Lammot du Pont began making sodium nitrate powder, a less expensive alternative to potassium nitrate-based powder, but its use was curtailed after the invention of dynamite. Both were less effective in rock blasting than dynamite, which quickly superseded the older blasting technology.

Nitroglycerine, invented by the Italian chemist Ascanio Sobrero in 1847, was notoriously unstable, could explode when jolted, and was extremely sensitive to heat, sparks, or other ignition sources. Its power and ability to remain viable when wet were distinct advantages over black powder, thus it was used for excavation of some of the hardest rock along the U.S. transcontinental railroad under construction in the 1860s. State laws on transport necessitated manufacturing on site, and it remained considerably more dangerous than black powder.

The invention of the blasting cap, by Alfred Nobel in 1864 and the stabilization of nitroglycerine through the use of diatomaceous earth changed this situation. Nobel’s dynamite allowed the easier transportation and more controlled initiation of blasting than could be achieved with nitroglycerine alone and was intended for use in mining and construction. In the United States, dynamite came into common usage after 1867 when Nobel licensed his process to a U.S. manufacturer. It became the first “high explosive” used in commercial blasting and saw its first large scale use in the construction of Hoosac Tunnel in 1876. Nobel went on to patent gelatin dynamites in 1875. Trinitrotoluene (TNT) was also developed in 1863 by Joseph Wilbrand as a yellow dye, but it was not used as an explosive for many years after its invention due to its high activation energy. It is less powerful than dynamite and has primarily been used as explosive ordinance. Dynamite remained the explosive of choice in construction and mining until 1956 when Robert Akre patented a lower cost alternative called Akremite that was made from ammonium nitrate and coal dust.

Later diesel oil was substituted for the coal dust, ammonium nitrate and fuel oil (ANFO) has stayed in common use since that time for rock blasting due to its stability and low cost. As of 2012 ANFO is by far the most commonly used explosive in North America. Other developments have expanded the blasters’ toolbox since the development of ANFO with newer explosive products such as slurries, water gels, and emulsions.

Slurries and water gel explosives were invented by Dr. Melvin Cook in 1956 and was an alternative to ANFO in wet blastholes. Later emulsion explosives (1969) were developed by the blasting industry.

Developments in detonation cords, electric delay detonators, and shock tube detonators have further widened the available tools and techniques that can be used to fragment rock and better control the effects of blasting.