Breaking down climate change impact by stage, impact from RACER remains the same, while upstream impact is reduced (Table 6.) Table 6 – Climate change impact by stage for rougher concentrate feedstock. Stage Share kg CO₂ eq. per kg Cu Cathode Upstream Concentrate (Mining + Comminution + Flotation) 76% 2.87 RACER Process 19% 0.74 SX/EW 5% 0.18 The substantial improvement in the rougher concentrate scenario across impact categories is driven by several compounding factors. Eliminating the cleaner flotation circuits removes significant water, chemical and energy inputs, including calcium oxide and multiple collector reagent stages. Improving total copper recovery reduces the upstream footprint per kg of cathode. 5. RACER for Bulk Sulfides — The Zero-Waste Vision The fundamental barrier to new copper mine development is not capital or geology—it is community acceptance. Long permitting timelines, frequently exceeding a decade, are driven in large part by well-founded concerns about the long-term management of sulfidic mine tailings. Even when permits are granted, many mines face legal pushback based on these concerns, which can further delay production by many years. When sulfide minerals in tailings are exposed to oxygen and water, they oxidize to produce sulfuric acid and heavy metal leachate—Acid Mine Drainage (AMD)—a liability that can persist for centuries after mine closure. AMD is one of the most significant sources of water quality impairment from mining globally, and the specific concern most frequently cited in community opposition to new mines and expansions. Still Bright’s RACER presents a pathway to eliminate AMD risk, which does not merely reduce environmental impact: it removes the primary objection to social license. Conventional flotation is selective: it is designed to concentrate only copper-bearing sulfide minerals, leaving the majority of non-copper sulfides, such as pyrite ad pyrrhotite in the tailings. The residual sulfides are what generate acid. The solution is conceptually straightforward: extract all the sulfides, not just the copper-bearing ones. This has occasionally been done with gold mines to recover the gold trapped within pyrite but it has not been employed with copper mining since the bulk sulfide concentrate cannot be processed by traditional smelters, which require high-grade, selectively floated feed. RACER is capable of extracting copper from this bulk sulfide concentrate: thus RACER is the enabling technology for a category of resource development that would otherwise remain stranded. The consequence of bulk sulfide processing is transformative for waste characterization. Virtually all sulfide minerals are extracted from the ore and processed through the RACER reactor, rather than deposited in a tailings storage facility. The remaining waste stream—primarily gangue mineral oxides—is depleted of the sulfide minerals required to generate acid. These tailings are chemically stable and should classify as non-acid-generating (NAG). Unlike conventional tailings, which require active management and monitoring in perpetuity, NAG tailings do not generate acid
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