Performing decking with the use of an inflatable plug in high or total submergence applications in blastholes to improve final wall profile stability

摘要

The overarching goal in modern drill and blasting operations is that of optimising miningoperations to achieve higher levels of productivity, safety, profitability and sustainability. Airdecking, a technique used in drill & blasting to optimise explosive product use while achieving atarget rock fragmentation, is a technique that when executed correctly is proven to achieveconsistent results independent of rock strength and the position of the holes (single, multiple,vertical, slanted), as well as being proven to reduce super-fragmentation (under-size or fines)while able to achieve optimal fragmentation, especially in the stemming zone. The ‘shockabsorber effect’ if the air deck reduces ground vibration and air blast. Additionally, the practiceof loading explosive product directly in saturated ground without dewatering or lining prior is anincreasing global trend.Often operators are faced with loading saturated blast holes in pre-splitting applications whereaccurate positioning of the decks is critical. In deep holes the issues of hydrostatic pressure atdepth coupled with the difficulty of deploying and accurately positioning the decking plug underup to 200’ of water requires an innovative solution.It was found that by lowering an inflatable plug in the uninflated state by a dropline hose,accurately positioning the plug in the blast hole according to the shot design, then inflating theplug in-situ allowed for compensation of the hydrostatic pressure exerted by the water columnwith the operator at the surface able to achieve the precise pressure needed to fix the plug firmlyin the target location. This was achieved with the use of pressure sensors located in the plugfilling head. Once inflated to the target effective pressure, the hose is disconnected from theannular snap sealing valve on the plug. As the inflatable plug was fully inflated the explosiveproduct and/or stemming material could be loaded immediately the hose had been decoupledfrom the inflated plug and retracted to the surface, increasing on-bench productivity.The use of an air inflated plug was shown to provide a safe, simple method of blocking blastholes in numerous applications, it eliminated some of the complexities and risks associated withusing aerosol inflated plugs, and provides solutions to some of the most challenging blastingapplications, the most challenging being deep submergence underwater decking.