612 2. LCA GOAL, SCOPE, AND METHODOLOGY The Life Cycle Assessment was conducted by Minviro to ISO 14044 standards using the Environmental Footprint 3.1 (EF3.1) impact assessment methodology and ecoinvent 3.11 background data. Results are cradle-to-gate, from raw material extraction through copper cathode production. The analysis explored two feedstocks: copper concentrate and rougher concentrate. The copper concentrate feed was assumed to be 25 weight percent copper. Still Bright’s RACER system is uniquely positioned to enable reductions in upstream processing. A system extension was conducted applying RACER to a lower-grade rougher concentrate—a product of less intensive flotation that skips the cleaner circuits used to produce high-grade concentrate. The trade-off is a lower copper grade (19% Cu vs. 25% Cu), offset by significantly reduced upstream energy and chemical consumption. 19% Cu was chosen as a conservative assumption: Still Bright has demonstrated the ability of RACER to extract copper from resources as low as 4% copper by weight without an increase in acid or other reagent consumption. Table 1 illustrates the input assumptions for the LCA. The LCA studied the impact of RACER for a typical mine profile in Arizona, United States. The system boundary was cradle-to-gate, with the bradel being unmined ore and gate being 99.99% copper cathode. Electricity for the RACER process was assumed to be renewable. Upstream electricity was assumed to come from the Arizona 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 98-99% 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
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