DefinePK

Abstract

Fragmentation has a considerable effect on the efficiency of the loading and transportation of the ore. If the fragmentation is coarse, then fragments are further required to be fragmented which involves extra time and cost. Research has proved that the rock fragmentation depends upon the delays introduced in a blast. Normally, shock tube detonators are used in Indian limestone mine blasting for providing the delay. Electronic detonators are also used in the Indian limestone mining industry, but their use is rather scanty. A little work in limestone mining is reported as regards to the assessment of the rock fragmentation distribution resulting from the blasts initiated using electronic detonators. In the present work, seven blasts have been monitored in a limestone mine to assess the effect of electronic and shock tube detonators on rock fragmentation. The blasts have been conducted in similar rockmass and with drill and blast parameters except the type of the detonators. Wipfrag image-analysis software has been used for the estimation of rock fragmentation in the muckpile. Results indicate that the blasts with electronic detonators yielded finer fragmentation than those with shock tube detonators. A reduction in oversize fragmentation in the blasts with electronic detonators can be attributed to an increased crack density, timely interference of the stress waves, and entry of gaseous products of blasting in the cracks generated in the rockmass. The result is corroborated by a reduction in the rock breaker operation time. The results indicate that the electronic detonators may pose a technical alternative to shock tube detonators in the investigated rockmass.