Minimizing Mining Dilution, Ore Loss & Misclassification by Accounting for Blast Movement
Accounting for blast movement in porphyry or manto copper deposits can have a significant impact in the reduction of ore loss, dilution and misclassification, resulting in increased ore recovery. Blast movement monitoring (BMM) for grade control is a holistic practice used to account for ore displacement caused by blasting, with the goal to accurately adjust the contacts of mining polygons.
Shaw et al (2013) present a reconciliation model for mining operations, which comprises data inputs ranging from ore reserve definition to milling. More specifically, on a mining grade control level, the authors very clearly emphasise blast movement as a major component of variability in reconciliation. It is therefore recognised at many operations around the world, that grade control is not complete until blast movement is accounted for (Thornton, 2009). Unfortunately, there are still a number of mines, particularly gradational base metal operations, throughout the world that do not account for blast movement.
This paper summarises the results from three Copper mines in Peru and Chile that have measured blast movement: Mine A – Porphyry-Skarn Copper – Molybdenum deposit in Peru; Mine B – Porphyry-Skarn CopperGold-Zinc deposit in Peru; and Mine C – Manto Copper-Silver deposit in Chile.
The projects consisted of placing a number of BMMs in many blasts over the past decade. The data collected was used on a blast-by-blast basis to accurately translate their ore polygons. In each instance, this new practice of translating ore polygons based on measured movement, was compared to the mine’s previous practice of ignoring blast movement, and simply mining their ore polygons in their in-situ locations. In order to evaluate the effect of blast movement on ore recovery, ore loss, dilution, and misclassification. The results are presented herein.