The Effect of Fragmentation Specification on Blasting Cost

Abstract

Drilling and blasting are seen as sub-systems of size reducing operations in mining. To have better design parameters for economical excavation of mineral production and fragmentation, the comminution and fragmentation operations need to be studied and optimized independently, as well as together, to create optimized use of energy and cost-effective operation. When there is a change in drillhole diameter or fragmentation specification, changes in the blast design parameters are required affecting the cost of a drilling and blasting operation. A model was developed to calculate blast design parameters and costs on the basis of the required 80% fragment size needed for crusher operation. The model is based on previously developed fragmentation models, found in the literature. The model examines the effect of drilling diameter on blasting requirements to achieve certain fragmentation targets and calculates blast design parameters and costs for a range of diameters from 75 to 350 mm. To examine the effectiveness of this model, two different 80% passing sizes of fragments have been considered. It was shown that cost optimization occurs at an intermediate diameter, since there are opposing trends of the effect of diameter on powder factor and accessories needed. To achieve a certain fragmentation target, the total cost of drilling and blasting shows a clear trend allowing an optimum selection of diameter. The selected diameter also allows the examination of the suitability of the drill machine under the given geological and operational conditions of the drilling site.