631 Example 1 Laboratory-scale gangue rejection tests were conducted on five copper feed types from a South American concentrator where a demonstration plant of Metso’s CPF technology is installed. Feed grades ranged from 0.9% to 2.2% Cu, with P80 values between 150 and 500 µm. Coarser particles (+150 µm), which contained 20–50% of the copper after grinding, achieved recoveries of up to 70%, and in the best case nearly 90% of the copper was recovered in only 50% of the mass. The enrichment ratio was significantly higher for the coarse fraction, confirming strong selectivity and effective gangue rejection, whereas finer particles (<150 µm) showed more entrainment. Example 2 Gangue rejection test work was conducted on a copper ore from the Antofagasta region (head grade 0.52% Cu, 65% solids), varying froth depth, reagent regime, and gas velocity. Results showed that 95% copper recovery could be achieved while rejecting 28% of the feed mass, or alternatively 42% of the mass could be rejected at approximately 90% recovery. This demonstrates that with only a 10% copper loss, plant throughput could potentially increase by up to 72%, provided that downstream grinding capacity is appropriately upgraded. These results further confirm the significant opportunity for process intensification and capacity expansion through early-stage gangue rejection. On the other side, the Concorde Cell is a high-intensity pneumatic flotation device designed to recover fine and ultrafine particles through high shear conditions and the generation of very fine bubbles. By significantly enhancing flotation kinetics for these size fractions, the Concorde Cell can produce high-grade concentrates with high stage recoveries at an early point in the flotation circuit. The operating principles of this technology, along with laboratory- and industrial-scale performance results, are reported in Yáñez et al. (2024) and in Kupka et al. (2025). From 1957 to 2020, flotation circuits have largely retained traditional layouts, most commonly Rougher–Cleaner–Cleaner and Rougher–Scavenger–Cleaner configurations, typically including a regrinding step before cleaning. However, operational experience has shown that in some cases the concentrate from the first rougher cell already achieves sufficiently high grades, making further grinding unnecessary. This has led to renewed interest in “scalping” strategies—recovering well-liberated, hydrophobic valuable particles as early as possible to produce high- or final-grade concentrate. By removing these particles upfront, unnecessary regrinding can be avoided, circuit capacity can be freed to treat more complex material, and overall circuit size and cost can potentially be reduced. While this concept is not new and is fundamental to flash flotation, it can be further enhanced when particle size conditions are suitable by using the Concorde Cell as a scalper in roughing, scavenging, or cleaning duties. On-site laboratory test work with the Concorde Cell was conducted in parallel with several Pb, Cu, Au, and Zn operations, with Cu and Au cases highlighted. In a copper plant treating fine, clay-rich material (P80 45 µm), the existing fines rougher–scavenger circuit achieved 57% Cu recovery at 6% grade. The Concorde Cell, operating as a scalper, demonstrated the potential to increase recovery by around 10% at similar grade, or alternatively to sacrifice grade and boost recovery by 20–30%. In a Cu–Au concentrator where stirred-stage flotation cells already acted as a scalper after regrinding, the circuit recovered 52% of the gold at 14 g/t. Test results indicated that a single Concorde Cell could outperform the existing system, delivering up to 15% higher gold recovery at comparable or improved concentrate grades. Together, these emerging flotation technologies enable a rethinking of traditional flotation circuit design by incorporating pre-concentration using the CPF Cell and scalping with the Concorde Cell. This integrated approach offers substantial reductions in both capital and operating expenditures, while simultaneously improving metallurgical performance and advancing sustainability objectives. 2. REIMAGINED CONCENTRATORS By integrating Coarse Particle Flotation (CPF) for early-stage ore pre-concentration together with the Concorde Cell as a scalping device, flotation circuits can be redesigned in a more streamlined and efficient way. A conceptual “base case” copper flotation circuit can therefore be developed, drawing on established chalcopyrite processing flowsheets and supported by real plant flotation performance data.
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