EVALUATION OF ROCK PROPERTIES FOR OPTIMIZATION OF FRAGMENTATION QUALITY IN SOME SELECTED QUARRIES

Abstract

This work deal with evaluation of rock properties and fragmentation sizes to predict fragmentation quality. Rock fragmentation, which is the fragment size distribution of blasted rock material, is used in the mining industry as an index to estimate the effect of bench blasting. Rock samples collected from three quarry locations were used for point load strength index, Uniaxial Compressive Strength, slake durability test and rebound hardness value were determined. Split software was used to determine the fragment size distribution and modified Kuz-Ram methods were used for fragmentation prediction. The mean values for Uniaxial Compressive Strength are 121.376 MPa, 129.2 MPa, 119.048 MPa for Samchase Quarry, F.M. Quarry and F.C.C Quarry respectively. The mean values for the point load were 11.135 MPa, 12.80 MPa, 10.50 MPa for Samchase quarry, F.M quarry and F.C.C quarry respectively. The slake durability index values reduce generally for all the quarries for both wet and dry samples. The difference was less than four for all the quarries. Ten readings were recorded at the three quarries for determination of rebound hardness values for the rocks. The mean rebound hardness values are 44.4 for Samchase Quarry, 48.2 for F.M Quarry and 42.3 for F.C.C Quarry respectively. The fragments were compared to the gape of the crusher, 0.1 meter was said to be undersize, and 0.6 meter above was said to be oversize. The average fragment sizes varied for the blasts for all the quarries. A general trend of under estimation of the undersize (< 0.1 meter) and over estimation of oversize (≥ 0.6 meter) was observed using Modified Kuz-Ram models as compared to the Split image analysis obtained on the field. A software was design compute for both blast design and fragmentation prediction, the software was design using java programming language, the software compute and gives result to users within few seconds. The rock properties for the three quarries revealed that the rocks are strong and classified as high strength rock. This mean that a high powder factor and high strength explosives will be required for the fragmentation and the rock material is durable.