Evaluation of blast efficiency in aggregate quarries: facts and fictions

Abstract

Evaluation of blast efficiency in quarrying of aggregate stones is one of the most important decisions that should be made by quarry operators for productivity assessment. The regulatory authorities also evaluate blast efficiency for environmental safety compliance. In carrying out this task, there is usually a conflict of interests between the quarry operators and the regulatory authorities. The quarry operators wish to blast and deliver the run-off-mine (ROM) to the processing plant at the least minimum cost with little or no boulders. On the other hand, the regulatory authorities want blast operations to be carried out with minimum disturbances to the environment irrespective of their incurred costs, fragmentation distributions, and effects on further quarrying processes. This conflict of interest calls for different approaches for evaluating blast efficiency by the various interest groups. Nevertheless, there must be an established standard that considers both process efficiency and environmental safety and acceptable to all the critical stakeholders in the sector. However, many of the currently available approaches and models for evaluating blast efficiency do not include safety but production efficiency. The chosen method primarily depends on the further use of quarried products. While quarry operators may evaluate blast efficiency by counting of boulders, shovel loading rate, visual observation, fragment size distribution, and cost analysis, the regulatory authorities majorly based their judgment on the level of blast-induced ground vibration by measuring the peak particle velocity of production blasts. This paper attempts to suggest a common ground and wholistic approach for evaluating blast efficiency and make a distinction between blast efficiency and fragmentation efficiency.