What face round would work best and why?
Underground mining and construction projects face several challenges unique to the underground environment compared to the surface environment. The goals are the development of an effective blast pattern that minimizes cost, maximizes face advance, and provides the desired fragmentation and face profile. In addition to these goals, mines must consider the very real operational problems that occur, such as drill deviation, ground vibration, and deadpressing1 or sympathetic detonation2 of explosives. These operation problems lead to increased costs and decreased production in the mine, hurting the bottom line.
Combined with these problems, underground blasts can be difficult to monitor and evaluate due to tight spaces, dust during the blast preventing video, and the need to evacuate the immediate area with no clear line of sight to observe performance. This creates an environment in which most mines know that blasting can be improved in their underground operations, yet most are hesitant to change due to fears of the shot freezing, misfires and questions about how to achieve a proper design. Unlike with surface blasting, the explosives companies, and shot service providers also offer limited assistance or knowledge in the underground blasting realm, leaving underground operations in the dark. It is for these reasons that most underground operations are operating decades behind the current technologies and incurring significant costs, both real and hidden, from their blasting operations.