Modifications in the Firing Pattern, Stemming Column and Bench Stiffness for Improved Blast Performance in Limestone Quarry of the Philippines-a Case Study

摘要

The present paper is a case study from the limestone quarry of the Philippines where major problems, in terms of improper fragmentation (large boulder count, poor front end loader performance (FEL), improper wall control, and poor heave characteristics of the muck piles), were witnessed on the 6m high limestone benches, The paper highlights the marked improvements in fragmentation results by changing the diagonal firing pattern to V-type firing pattern, and also, by making suitable adjustments , in the stemming column. Looking at the said improvements due to said changes, advantage of these changes were implemented on 9 m high benches of the same quarry to reap the benefit of reduced bench stiffness, by way of expanding the mesh area (S X B)in the subsequent blast rounds. The increase in mesh area was done incrementally from the existing 8,96 m~2 to 12 m~2. The results were meticulously registered in the field, and clearly depicted definite improvements in the blast performance in terms of increased powder factor, reduced boulder count, reduced FEL cycle time and better heave characteristics of the blasted muck.