Unlocking value in marginal grade ores through selective blast-induced fragmentation and screening-based pre-concentration

Near-surface, high-grade deposits of critical and strategic minerals, including copper and zinc, have largely been depleted, shifting future mining towards lower-grade, heterogeneous ore bodies. Concurrently, environmental, social, and governance (ESG) obligations are driving the industry to reduce energy consumption, minimise water use, and limit tailings storage footprints. These pressures demand innovative mining strategies that maintain economic viability while meeting sustainability targets. Ore pre-concentration as a key leverage point of Grade Engineering (GE), offers a pathway to address these challenges by enabling early-stage ore–waste separation. Selective blasting provides a practical mechanism for GE, producing finer fragmentation in ore zones and coarser fragmentation in barren gangue. This approach facilitates downstream separation via conventional bulk screening, reduces comminution energy and water demand, and decreases material reporting to tailings storage facilities. Coarse rejects may also be valorised for in-mine or external applications, supporting circular economy principles. This study investigates the feasibility of exploiting differences in the mechanical properties between ore and waste to achieve selective fragmentation, enhancing ore pre-concentration at the mining face. A hypothetical scenario is analysed in which soft, high-grade ore pockets are randomly distributed within a hard, low-grade matrix. Conventional mining would classify the bench as waste or marginal ore, whereas GE enables targeted fragmentation to recover significant copper value. The analyses demonstrate that pre-concentration via blasting and screening is particularly valuable in heterogeneous, marginal-grade deposits where selective comminution can optimise recovery, reduce downstream energy demand, and improve processing capacity.