Empirical methods for the calculation of the specific charge for surface blast design

A literature review of empirical methods for the calculation of the specific charge for blasting in surface mines is presented. These methods are based on seismic wave velocity, drilling indices, the efficiency of transferring explosive energy, rock mass properties and blastability indices. The parameters considered in these methods are studied and the major factors that determine the specific charge are identified. Besides the rock mass and explosive properties, it is found that the desired degree of fragmentation distribution, transfer and utilisation of explosive energy greatly influence the specific charge. All these factors should be considered while optimising the specific charge for surface blasting operations.