ABSTRACT
The extension of surface mining and the evolution of the drilling equipment have made bench blasting the most popular method of rock fragmentation with explosives. It has even been introduced and adapted for some underground operations. In small diameter blastings, the Swedish technique developed by U. Langefors and B. Kihlstrom can be followed, while in the larger it is better to use the crater technique established by Livingston or American criteria. In conventional bench blasting, the cut of the rock at floor level is achieved by subdrilling and by the concentration of high strength explosive in the bottom of the vertical blastholes. The configuration of the blasting that produces large blocks is different from conventional bench blasting. Two basic objectives consist of getting an adequate cut at floor level and a clean separation along the plane formed by the blastholes with the minimum splitting of the rock in front of that plane.
