Increasing Back Break Using High Speed Blasting Techniques

摘要

RAG Coal West, Inc., Belle Ayr Mine is located in the heart of Wyoming's rich Powder River Basin coalfield. Belle Ayr utilizes an open pit, truck/shovel operation to strip the overburden off the 70'seam of sub bituminous coal. Our excavation capacities consist of a 301 Marion with a bucket size of 52 cubic yards, and a 4100 XPB P&H with a capacity of 76 cubic yards. Production levels on these machines are closely monitored utilizing the Modular Mining Dispatch system. RAG Coal West, Inc. is a coal mining business that utilizes the effectiveness of teams as one of their strategies. Technicians have a certain amount of control over their own Team Process. The Drilling & Blasting Team is an assortment of blasters with varying experience levels. We have been able to think outside of the box when it comes to certain "proven" methods of blasting. The arrival of Electronic Detonators at RAG Coal West, Inc. allowed the group to get "way out there" in terms of contradicting certain blasting rules of thumb. We now had the ability to do so many different things that were not available to us by use of the standard non electric shock tube delays. Without trying to change too many parameters at once, we identified the path that we wanted to follow in testing some of our theories. We had to overcome the additional cost of the electronic detonator by increasing the pattern size sufficiently to make it a "break even" blast. After some significant testing, it was apparent that the production output of the mine was not negatively impacted from the use of electronic detonators. When the electronic detonators and firing system was proven, we then began our testing process. We wanted to fire the blast-holes in a manner that allowed for more interaction of the initial shock wave. Our efforts were directed at increasing fragmentation by utilizing the collision of shock waves between holes. Delay between explosive charges had to be reduced significantly to create the desired effect. This non-conventional timing method has increased fragmentation, but it also resulted in increased back-break. It was observed however that this back-break was a positive by-product of this timing method. We witnessed up to a 31 percent increase in productive yield as a result of high speed blasting.