Drill-and-blast unit productivity in cost per tonne is calculated by dividing the overall drill and blast cost by the overall tonnes blasted. This includes drilling parameters, consumption and the cost of explosives used, quality of blast fragmentation, impact on the environment, and operational efficacies. The basic formula is:
Cost per tonne = Total drilling and blasting cost / total tonnes blasted
Drilling hole depth, hole diameter, spacing, explosive type and quantity used, blast generated fragmentation size distribution, vibration and environment compliance, and blast related operational downtime. Proper fragmentation reduces the downstream costs of haulage, crusher, and grinder and maximizes overall productivity.
To determine this properly, you must gather balanced data involving blast design and execution, quantify results with empirical measurements (such as digital imaging and sieving), and compare costs and workings with industry standards. The blast design is then refined with parameters shifted to increase the cost per tonne but with compliance and working efficiency kept constant.
Briefly, drill-and-blast productivity cost per tonne is quantified by blending the direct costs and blast performance measures in terms of understanding the improvement areas and efficacy of the drilling and blasting undertakings.
