ABSTRACT: Rotary blast hole drills were observed in fourteen rock types at eight open pit mines. The netpenetration rates of the drills were calculated from the performance measurements. Rock samples werecollected from the drilling locations and the physical and mechanical properties of the rocks were determinedboth in the field and in the laboratory. Then, the penetration rates were correlated with the rock properties andregression equations were developed. The uniaxial compressive strength, the point load strength, Schmidthammer value, cerchar hardness and impact strength show strong correlations with the penetration rate. Theequations derived from Schmidt hammer and impact strength values are valid for the rocks having uniaxialcompressive strength over 25 MPa. The Brazilian tensile strength and cone indenter hardness exhibit quietgood correlations with the penetration rate. Concluding remark is that, the point load, the Schmidt hammerand the impact strength test which are easier tests to carry out can be used for the rapid estimation of thepenetration rate of rotary blast hole drills
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