BLAST OPTIMIZATION AT BLUE CIRCLE CEMENT

摘要

Blue Circle Cement's Ravena, New York quarry mines approximately 6.7 million tons of limestone per year. Blasting occurs approximately twice a week on three separate benches. Shots average 60,000 tons but can range up to 140,000 tons. Ongoing scrutiny of the drilling and blasting program allows for maximum blast efficiency which results in lower overall mining and crushing costs. Close cooperation between management and explosives supplier assures Blue Circle Cement's objective, "To develop, implement, and continuously improve a measurable drilling and blasting system that will optimize the total mining and crushing costs while ensuring compliance to safety and maintaining or reducing the environmental impacts of blasting".Blast designs are tailored separately for each of the three benches. All benches are limestone, however varying geologic conditions and rock properties between the three benches necessitates site specific and ongoing blast monitoring and design implementation. A computer blast modeling program has been utilized, since the summer of 1992, to help with the blast design. Blast monitoring tools such as high speed cameras, laser profilers, borehole deviation measurement systems, fragmentation measurement systems, and seismographs have provided a means of verification to blast model prediction to ensure Blue Circle's goal of lowering overall mining costs while maintaining commitments to safety and the environment.Since the measurement system has been brought on line, blast improvement based on trial and error has been eliminated and valuable time and resources have been saved. It has become evident that small increases in blasting costs provide improvements in shot quality and great returns in overall mine costs. Due to these constantly improving returns, the quarry continues to deliver production rock to the plant at lower costs despite having to mine increasing amounts of overburden.