810 Site constraints or additional investments required to achieve the lowest specific energy configuration may delay implementation, leading operators to prioritise higher-throughput options such as Sim 8. When carbon intensity is considered, an alternative configuration such as Sim 7 may provide a more balanced outcome, maintaining strong production performance while delivering lower overall carbon emissions. 4.5 Considerations for Interpretation and Key Insight This example applies average consumable-use values and does not simulate wear mechanisms or scenario-specific changes in liner or grinding media performance. Replacement intervals reflect operational averages rather than dynamic responses to varying process conditions. The purpose is illustrative: to demonstrate how consumables can be integrated into optimisation-based carbon indicators using available operational data without implying predictive accuracy for site-specific wear behaviour. Despite these simplifications, inclusion of consumables materially alters both absolute carbon intensity and differentiation between scenarios. Consumables represent a first-order contribution comparable in magnitude to achievable energy-efficiency gains; carbon optimisation therefore cannot be reduced to energy optimisation alone. A sensitivity analysis using different regional electricity emission factors (Global mix, India, Peru, and Finland) shows that the proportional importance of consumables increases as grid carbon intensity decreases, ranging from 7% under a carbon-intensive grid to 44% under a low-carbon grid (Figure 2). This demonstrates that as electricity systems decarbonise, Scope 3 emissions become structurally more dominant within comminution. Consequently, energy-only metrics become progressively less representative of total carbon performance. Figure 2: Relative contribution of consumables in different grids. 5. DISCUSSION & CONCLUSIONS This study shows that incorporating carbon considerations into process optimization (PO) workflows is feasible when treated as an overlay rather than a separate modelling exercise. Framing the analysis within a conventional PO structure and introducing life cycle assessment (LCA) indicators using a shared inventory allows carbon results to be interpreted alongside operational variables such as throughput, specific energy, and circuit performance. Carbon performance in mineral processing involves energy use, consumables such as grinding media and liners, services, maintenance, and Scope 3 emissions. Using kg CO₂e per ton from electricity is a well-established starting point for screening, but it is only the first step. In this case, electricity and consumables are implemented to demonstrate how material-related emissions can be integrated into a comparable carbon KPI that reflects the combined effects of energy and materials rather than energy alone. Including grinding media and mill liners is a practical and effective second step toward a more comprehensive carbon evaluation. By applying traceable emission factors and transparent usage metrics— 14% 32% 7% 44% GLOBAL (GLO) PERU INDIA FINLAND CONSUMABLES RELATIVE CONTRIBUTION Electricity (Scope 2) Consumables (Scope 3)
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