FLOTATION
Upfront, in the grinding circuit, there is potential to reject 50 % of the mass already before going to the final grinding stages. Carvalho:“ Even if we remove 30 % to 40 % of the total non-valuable mass at that point, we can create final tailings there already. So that is a game changer, not only for the potential capacity increase but because significantly coarser final tailings mean you can use a totally different approach to tailings processing, like dry stacking.”
Rinne:“ If you must classify the ore at the beginning of the circuit before CPF, it means that all the fines have to be separately processed in a conventional flotation circuit. If you, for example, have 20 % of the plant throughput going to the CPF, your gangue rejection is limited to what is going to the CPF. When feed classification is not required, the gangue rejection potential can be significantly greater, and it allows us to have a higher mass pull and achieve higher recovery. In all the gangue rejection applications we’ ve studied so far, we haven’ t needed classification at all.”
Metso did test work and simulation in a gangue rejection application without Sampo feed classification, where it was rejecting 45 %, which means Sampo had a 55 % mass pull, meaning you could increase the plant throughput by 82 %. Carvalho:“ So not classifying the feed has a huge impact in the potential of increasing the plant capacity. Practically speaking it is hard to increase a plant throughput by this order of magnitude in a brownfield situation but in a greenfield project, it means that the plant can process a much bigger tonnage of ore with a much smaller footprint.”
What does that plant look like from a comminution point of view? What type of comminution is ideal to maximise the potential of CPF? Rinne:“ In the gangue rejection upfront, the CPF will change the comminution strategy as well. The same equipment works, but we will target much bigger particle sizes, which will save grinding capacity or increase plant throughput. New Metso Loesche technology is also a very interesting alternative here. We will end up with a coarser first concentrate, and a Vertimill is then ideal for regrinding the CPF concentrate. All of this means a lot of saved cost and energy.”
FLS RFC continues to garner interest
Staying with innovative flotation cells, but for fine particle recovery, FLS says its REFLUX™ Flotation Cell( RFC™) radically alters perceptions of froth flotation performance. It operates at extreme levels of gas and feed flux, and fluidisation wash water to deliver up to tenfold higher throughput, with enhanced grade and recovery, all with a smaller plant footprint.
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The FLS RFC is now seeing increased interest across metal sulphides and industrial minerals- this shows a full sized cell trialled at KGHM’ s copper operations in Poland
The high-shear pre-contacting spargers and inclined channels allow operation under air-flooded conditions, delivering high operational gas flux rates while reducing bubble size. This increases the available bubble surface area flux by a factor of four compared to traditional flotation cells, significantly increasing collision and attachment rates. Contact between bubbles and floatable materials occurs in a high shear rate environment, elevating recovery rates.
Lance Christodoulou, Global Product Director for REFLUX™ Technologies at FLS told IM:“ The RFC is a leading flotation technology but still relatively new in the industry. We are now seeing major interest because of its ability to shift the grade recovery curve and reduce the required flotation volume substantially, which has a significant CAPEX and OPEX impact. We’ re seeing improved performance versus conventional flotation in terms of both recovery and grade. This includes copper applications, where we completed trials with KGHM in a full-scale installation in Poland. This EIT RawMaterials funded project is now complete but now we have another major miner interested in using the full-scale cell we built for that work for moly flotation.”
In that specific application, FLS was able to reduce the required retention time by a factor of 10. So where the plant was utilising a retention time of 30 minutes, the RFC was able to achieve the same recovery and grade in 3 minutes.
Elsewhere, at a major southeast Asia copper mine, a 2 m RFC( RFC2000) was part of a successful pilot trial for processing smelter slag tails and cleaner scavenger tails, assessing potential recovery improvements.
Another example in copper is with BHP at Carrapateena, where a RFC was tested alongside a Glencore Technology Jameson Cell. This work was presented in a paper at MetPlant 2026. Carrapateena conducted a pilot test program with the RFC and investigated its effectiveness at rejecting fine non-sulphide gangue( NSG) without reduction in copper recovery. This was in a cleaner-scalper duty. The RFC was found to recover copper at an equivalent rate to the existing plant whilst reducing entrainment of fine non-sulphide gangue by approximately 50 % in fine size fractions. Flotation tests of the RFC concentrate resulted in no meaningful increase in copper grade, indicating concentrates produced were near the maximum grade achievable by flotation.
Considering the promising results from the pilot plant, BHP and FLS agreed to demonstrate a 2 m diameter RFC( RFC2000) at Carrapateena. The RFC2000 is now being delivered and installed later this year and will increase the capacity of the cleaner circuit, resulting in modest increases to overall recovery and concentrate grade.
There are also now commercial installations of the RFC – namely at a US industrial mineral mine operated by a global industrial minerals producer. It selected multiple REFLUX™ Flotation Cells( RFC™) for service in a reverse flotation application. FLS:“ In this challenging duty, silica is removed to produce a high-grade product. This milestone is the culmination of lab testing, pilot testing, and a full-scale industrial trial. One RFC™ has the capability to replace a row of up to ten conventional cells, significantly reducing the flotation plant footprint as well as operating and maintenance costs.” FLS added:“ Reducing OPEX on a duty like this takes a real partnership. Many thanks to the customer’ s team, who know their process and have tested our technology thoroughly. That work continues together, backed by our process technology expertise and lifecycle support. Partnerships like this turn innovation into the trusted standard.”
Moving to FLS CPF technology, coarseAIR is based on the REFLUX Classifier( RC), a highly efficient fluidised bed separator widely adopted in the mining industry to improve fine particle recovery. The coarseAIR solution combines the hydrodynamic advantages of the RC with the selectivity benefits of flotation to float larger particles than conventional flotation processes, which are typically limited to particles of-200 μm.
The coarseAIR cell operates as an aerated fluidised bed separator, where coarse particles are floated without the
International Mining | OCTOBER 2026