tir secondaire

OBS: L'objectif de ce tir est de corriger ces anomalies : pétarder les gros blocs, forer et tirer les bosses, etc.

CONT: Irrespective of the method of primary blasting employed, it is usually necessary to reblast a proportion of the rock on the quarry floor so as to reduce it to a size suitable for handling by the excavators and crushers available. Two methods of secondary blasting of rock are available. The first is to fire a charge of explosive placed on the rock and covered with clay, the shock of the detonating explosive breaking the block. This is usually called the plaster or mudcap method. The second technique, known as pop-shooting, is to drill a hole into the block and fire a small charge in this hole, which is usually stemmed with quarry fines.