Formation of slot cut for creating free face in solid limestone bench: A case study

Abstract The present case study pertains to the generation of free face in a solid bench of a limestone quarry located in the Philippines. Due to certain unavoidable operational circumstances, the bench was devoid of free face. Notwithstanding, it was essential to exploit the high grade limestone from the given bench. Given this, a suitable firing pattern was designed for the said bench to form a 75 m long and 15 m wide opening slot cut. The field scale implementation of the designed firing pattern was conducted methodically to generate the opening slot and provide a free face for the subsequent blasting operation on the bench for regular production of limestone. State-of-art digital image analysis of the blasted muck in conjunction with excavator cycle time observation, boulder count and measurement of throw were deployed to evaluate the efficacy of the designed firing pattern at pilot as well as full-scale blast. The designed firing pattern yielded satisfactory fragmentation results.