The rock fragmentation control in long hole blasting – case study Antam Pongkor underground gold mine

Abstract

The increase of reblasting activities due to the significant number of oversize fragmentation result from blasting make escalation of explosive which decreases the productivity. The productivity decrease because the production cycle disrupted when the activity needs more time to get the same result. At Antam Pongkor Underground Gold Mine, the target of fragmentation is less than 40 cm. More than that size, the fragmentation need to be reduced with reblasting. From the observation, the oversize fragmentation in the long hole blasting system is 34%. This study is a concern on how to reduce the oversize fragmentation to optimize mine activity. By improving drilling technique like shorten the boreholes distance, changing the blasting pattern, installing plastic pipe and standardizing the explosives and delay pattern, the oversize fragmentation can be lowered. The result of the study, the oversize can be reduced to 14% which help the miner to do effective and efficient mine activity. The implication of the lowered oversize fragmentation is the fall off reblasting activity number into 11 times which before the study is 18 times. In conclusion, the drilling technique improvisation can be the key to control the rock fragmentation in Long Hole Blasting.