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

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 75m long and 15m 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. To develop free face in the solid limestone quarry, seven firing patterns were designed for opening slot cut. Image analysis of the blasted muck in conjunction with other techniques was deployed to evaluate the efficacy of the designed firing pattern. The designed firing pattern yielded satisfactory fragmentation results. [Display omitted] ► We designed firing pattern for opening slot cut. ► We conducted pilot and field scale blasts. ► We evaluate the efficacy of design by fragmentation and other. ► The designed firing pattern yielded satisfactory fragmentation results.