Figure 1 – Simplified process flow diagram of Still Bright’s RACER. Copper cathode is produced from copper feed, which can be any copper-containing sulfide concentrate, including finished copper concentrate and rougher concentrate. Iron is captured as ferrous sulfate, sulfur is captured via the Claus process as elemental sulfur or sulfuric acid, and other metal co-products can be captured from metal-enriched residual solids via conventional processing methods. 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
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