grid (WECC). An economic allocation was chosen for impact assessment to enable understanding of impact based on market demand. 96.5% was chosen for copper recovery; this is conservative and was chosen to match typical smelter payability. RACER has consistently demonstrated 9899% copper recovery across a range of feedstocks. Table 1 – Input assumptions for the LCA. Functional Unit 1.0 kg copper cathode (99.99% Cu) System Boundary Cradle-to-gate Electricity (for RACER) Arizona Renewable Grid (0.05 kg CO₂ eq./kWh) Electricity (upstream) WECC Average Grid Economic Allocation 93% to copper; 6% to iron sulphate heptahydrate; 1% to hydrogen sulfide Copper Recovery (RACER) 96.5% 3. LCA Results – Copper Concentrate Feedstock The following results (Table 2) reflect the full cradle-to-gate system boundary including SX/EW, under the Arizona Renewable Grid electricity assumption. Table 2 – LCA results for copper concentrate feedstock, including climate change impact, acidification, energy demand for the RACER process only, and water use. Climate Change Impact 4.68 kg CO₂ eq. per kg Cu cathode Water Use 12.83 m³ world eq. per kg Cu cathode Electricity demand 1.09 kWh/kg concentrate Acidification 0.12 mol H⁺-Eq per kg Cu cathode A key sensitivity variable is the electricity grid assumption, which affects both the RACER process and upstream concentrate production. Three scenarios were evaluated (Table 3): Table 3 – Climate change impact for various power purchase agreements. Electricity Scenario Climate Change Impact Arizona Renewable Grid (base case) 4.68 kg CO₂ eq. WECC Average Grid 6.24 kg CO₂ eq. WECC Renewable Mix (PPA) 4.67 kg CO₂ eq. The result is highly sensitive to electricity sourcing. The Arizona Renewable Grid scenario—in which 100% of electricity across the mining, RACER, and SX/EW stages is matched by renewable
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