Methodology for the Selection of Optimal Blastholes Length in Underground Mining

摘要

Expansion of high – productive underground mining methods is significantly related to development of drilling equipment. Application of deep blastholes provided reduction of deve-lopment ratio. On the other hand, deep blastholes are limited by capacity of drilling equipment and worsening of blasted ore fragmentation due to deviation of blastholes. This paper presents the authors ten year research results of long blastholes application in under-ground extraction of copper ore in underground mine Jama Bor. In the analysis of Tilva Ros and P_2A ore bodies in Jama Bor underground mine, it was shown that increase of oversized ore fragments is proportional to increase of blastholes depth. It means that deviations of deep blastholes would be the most important limiting factor in their future application in Borska Reka ore body. The Paper provides methodology for selection of optimal blastholes depths. Main criterion for selection is a sum of costs, for drilling, blasting, development drifting and secondary blasting. Re-lation between costs and blastholes depths is shown through: development ratio, drill capacity, con-sumption of explosives, parameters of blasted ore fragmentation. The result is that increase of drill-ing accuracy provides increase of optimal blasthole depth. The significance of this optimisation is in the fact that efficiency of drilling equipment and pa-rameters of designed mining method depend on drilling depth