Computerized design of blasting parameters based on drillability index of jointed rock mass in roller bit drilling in open pit mines

Abstract

Blastability of rocks mainly depends on their strength (hardness) and jointing. Rock drillability is found both by Russian and foreign scientists using the rock strength and elasticity characteristics. In the meanwhile, practice shows that jointing in rock masses with joint sizes of 0.1–0.5 m increases the rate of drilling. Consequently, when determining the rate of roller bit drilling and drillability of rock mass, the jointing parameters of rocks should be taken into account. This article presents the found relations for finding the roller bit drilling rates, drillability index and the main blasting parameters in open pit mining in jointed rock masses. The relation of the roller bit drilling, drilling techniques and drillability index includes the hardness factor and the parameters of jointing. The formula of the drillability index of jointed rock mass is obtained. The validity of the relations is proved by the comparison of the calculation results with the physicotechnical properties of rocks, as well as with the Wenco system data on drilling in Verninsky Open Pit Mine of Polyuszoloto. Using the drillability index, the formulas are obtained for determining the powder factor and explosive charge weight per hole. On the whole, based on the drilling data, a dedicated software program is designed for determining the drilling index and the main blasting parameters in open pit mines at the preset fragmentation quality for jointed rock mass.The authors express their gratitude to V. I. Volkov, I. V. Rykov and N. N. Zakharov, specialists from Verninsky OPM, for their help in these studies.