Evaluation of bulk and particle sensor-based sorting systems for the New Afton block caving operation

Block and panel caving mines are increasingly being proposed for the excavation of massive ore-bodies located at depth. The lack of selectivity associated with the mining methods results in both ore and waste being caved and transported through material handling systems to the surface for processing and waste rock disposal. Sensor-based sorting systems provide an opportunity to automate the discrimination between ore grades and rock types, providing an enhanced level of selectivity for ore control and thereby improving mine productivity. To evaluate the potential to add value to a caving operation, a sensor-based ore sorting study, incorporating bulk and particle sorting systems, was carried out for the New Afton block cave mine. Results showed that rock from the copper-gold porphyry deposit is amenable to prompt gamma neutron activation analysis, and to X-ray fluorescence sensors. A conceptual flowsheet, where both technologies are used as separate unit operations, was evaluated. Test samples of varying copper head grades allowed an ore value calculation method to be developed based on the integration of continuous bulk sorting and particle sorting. The calculation method can be applied to block models of a future cave at New Afton and used to evaluate the change in the economic footprint. It was found that the concept demonstrated an improvement in the net smelter return of excavated material.