Optimizing the specific charge for limestone blasting at Aruwakkalu Limestone Quarry

Abstract

The objective of this research is aimed at optimizing the specific charge for limestone blasting at Aruwakkalu limestone quarry without leading to poor fragmentation of the blasted material. Thus, in reducing costs incurred during drilling and blasting activities, specific charge plays a vital role in open pit blast design as it affects many operational costs in mining activities. Therefore, at the quarry, specific charge is calculated for each blast and is monitored and maintained. Blasting parameters such as spacing and burden are already optimized at quarry according to the empirical formulae published by Langefors and Kihlstrom (1976).Therefore, when optimizing specific charge, it was first decided to change blasting parameters having the greatest effect on fragmentation such as spacing, burden, and charging method and evaluate the fragmentation of the blasted material because it is often difficult to optimize several blasting parameters simultaneously. Since fragment size directly affects crushing, a computer aided model called ‘Split Desktop’ was used to analyse fragmentation of material using digital photographs. Results of the four test blasts were analysed on cost basis. Thus, the blast geometry which resulted the lowest cost and the fragmentation within a manageable level is recommended to be practiced at the quarry in future.