2239 3. TECHNICAL FOUNDATIONS OF COMMINGLING IN MINE PLANNING Desing Principles and Material Characterization Commingling at Antamina is based on engineering principles that seek to combine the superior structural properties of waste rock with the low permeability characteristics of tailings (Boshoff, 2023). This combination results in a material with shear strength similar to waste rock and permeability comparable to tailings, creating conditions that restrict oxygen entry and water filtration, significantly reducing the potential for acid drainage generation (Ulrich & Coffin, 2015; Burden & Wilson, 2023). The characterization of commingled material is performed through analysis of five distinct structural configurations: rock-dominated uncompacted, fines-dominated uncompacted, rock-dominated compacted, fines-dominated compacted, and the "just-filled" configuration where fines exactly fill the voids between rock particles (Burden & Wilson, 2023). This latter configuration represents the optimal target of the commingling process at Antamina. Figure 142 Blend configurations after Wickland et al. (2006). Source: Burden & Wilson (2023). Integration into the Strategic Planning Process The integration of commingling into Antamina's mine planning follows a structured methodological approach that places tailings management with waste rock as central elements of decision-making. This global strategy allows for optimizing the mixture of materials from the mine to the plant, considering the operational and environmental constraints associated with the tailings storage facility. By incorporating tailings behavior in the early stages of planning, greater efficiency in resource use and better risk management are achieved. The global strategy is divided into three key axes: • Strategy 1: Ensure Future Expansions: The first strategy focuses on maximizing tailings storage capacity for current and future needs, leveraging Antamina's mineral resource and applying advanced technology to increase TSF (Tailings Storage Facility) capacity to ensure the mine's long-term operational continuity. • Strategy 2: Optimized footprint: The second strategy seeks to optimize the overall project footprint by balancing waste and tailings storage space. This approach aligns directly with commingling principles by maximizing efficient use of available land within the current operational footprint. • Strategy 3: Reduce upfront CAPEX: The third strategy focuses on reducing initial CAPEX to improve key financial indicators (IRR), which directly aligns with the demonstrated economic benefits of commingling, minimizing operational costs with a nearby TSF and optimizing CAPEX timing.
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