Prediction of the penetration rate of rotary blast hole drills using a newdrillability index

Rotary blast hole drills were observed in several formations at different o pen pit mines and quarries. Rock samples were collected as near as possible to drilling locations and mechanical and physical properties of the total 22 rock samples were determined. Indentation tests were carried out on the block samples from the same formations, A new drillability index for the pr ediction of the penetration rates of rotary blast hole drills and the mecha nical and physical properties of the rock formations was defined from force -indentation curves of indentation tests. A penetration rate model for rota ry for blast hole drills was developed using this drillability index. It wa s seen that the model was valid for the formations having uniaxial compress ive strength over 40 MPa and especially for carbonaceous rocks. The drillability index exhibits a significant correlation with the proporti onality constant k defined in the model. It is also seen that significant c orrelations exist between the drillability index and rock properties sugges ting that the proposed model may be used universally to estimate the penetr ation rate of rotary blast hole drills. (C) 2000 Elsevier Science Ltd. All rights reserved.