By Tom BoBo, Director of Technical Sales & Marketing, Split Engineering; Petra Webb, Geologist I, ASARCO, LLC

Blast planning involves the identification of rock mass properties, then designing a blast the achieves the desired Particle Size Distribution (PSD) for the Runof-Mine (RoM) to feed the next stage in comminution. Typically, the RoM PSD information is fed forward to the primary crusher or heap leach operations. The overall goal of any mine site for minimizing avoidable operational costs and maximize efficiency in comminution to achieve the desired PSD. Many costs are preventable with a real-time reporting fragmentation analysis system located at the dig face, which provides feed forward PSD to the crusher and feedback to blast planning engineers. If you don’t measure the results of blasting, you can’t improve the process.

Discussed in this paper will be the importance of providing real time fragmentation analysis as an important metric for determining energy factors for each hole and blast. This study presumes the energy factor is primarily determined by rock type, desired fragmentation distribution, and in-situ fracturing. Data has been collected over time at Asarco Mission mine in Arizona to support the evaluation of a shovel based PSD analysis system. The mine blasting engineers use blast patterns in their short-range planning, therefore; the energy input is changed based on the fragmentation analysis.

In this study, the geology and reported PSD are integral in determining the necessary energy factor for each material type. The crusher feed optimization is based on a blend of material and size. Location, geology along with PSD reported data, the optimum blend of material and size is achieved to feed the crusher and ultimate downstream mill throughput is key.

Split-ShovelCam was used for this study and is a fully autonomous digital fragmentation analysis system. The study determined it to be efficient and accurate by comparing reported PSD to proven hand-delineation software. It is expected that the blast designs can be further refined as initial testing and additional data is collected during the mining processes.