FLOTATION
Cenizas’ s Las Luces concentrator in Antofagasta, Chile. Approximately 30 % of the total tailings stream is processed, and the Sampo Cell has delivered a significant increase in overall copper recovery. In continuous industrial operation and across a broad range of operating conditions, the CPF cell consistently achieved copper stage recoveries exceeding 60 %, with recoveries above 80 % attained at moderate mass pulls. Concentrate grades were at least twice higher compared to the main concentrator feed grade, enabling the recovered material to be returned to the circuit for regrinding and subsequent conventional flotation, with the objective of increasing overall recovery. Importantly, the Sampo concentrate has been directly sent to the regrinding circuit without the need to dewater it, with solids percentage between 25-35 %. These results were obtained without excessive mass pull, supporting selective recovery of valuable minerals while minimising the impact on auxiliary equipment and downstream capacity.
“ The industrial-scale operation in Chile has validated both the performance and scalability of the Sampo Cell. The results show how customers can improve overall plant recovery without major changes to the existing flotation circuit,” says Antti Rinne, Vice President of Flotation at Metso.
Metso says the launch of the Sampo Cell further strengthens its leadership in flotation technology. Metso offers one of the industry’ s most comprehensive flotation portfolios, covering mechanical flotation, pneumatic flotation, flotation services, process expertise, digital optimisation tools, and aftermarket support.
Combined with Metso’ s crushing, screening, grinding, filtration, thickening, and tailings solutions, customers benefit from an integrated approach that optimises performance across the entire minerals processing flowsheet.
IM Editorial Director Paul Moore travelled to Metso’ s headquarters in Helsinki and its Research Centre in Pori, to find out more about the technology – meeting in person with Antti Rinne and with Marly de Avila Carvalho, Product Manager, Coarse Flotation.
Rinne commented:“ We investigated several different options on how to best do coarse particle flotation and tried to look at the big picture, what is making the existing CPF alternatives complex, especially for brownfield operations. We considered that the additional equipment required for fluidised beds was what made these current technologies complicated, in our view – and we saw that there might be ways to overcome those issues.”
Rinne added that the drivers to develop Sampo without using fluidisation were the need for multiple stages of classification, and the amount of water used – which means large pumps and significant energy consumption.“ More classification also means greater height, which in turn requires more structural steel and additional pumping, making it very expensive from an overall project point of view.”
“ As a result, the Sampo Cell enables a remarkably compact circuit design, with
IM Editorial Director Paul Moore with Metso’ s Marly de Avila Carvalho( right), Product Manager, Coarse Flotation; and Antti Rinne, Vice President of Flotation( left)
significantly lower height requirements compared with conventional flotation and other coarse particle flotation solutions. While feed classification is not required for the Sampo Cell, it may be beneficial in certain applications depending on the project requirements and, when applied, only a single classification stage is typically sufficient. This compact configuration can significantly reduce building height and overall plant footprint, making the technology particularly attractive both for greenfield projects and for retrofits with space and structural constraints.”
Carvalho added:“ One other advantage that I think is crucial is that if you are adding a lot of water in the cell, that water needs to go somewhere. And in the fluidised bed based equipment, that water goes to the concentrate, otherwise fluidisation will not function properly. So, the mechanical design of the equipment means that it dilutes the concentrate. So then that water needs to be removed from the concentrate for the concentrate to go to the grinding circuit and then return to the process. In our Sampo Cell, we don’ t have fluidisation water, we are just adding enough water for the flotation process, and the solid percentage that we are getting in the concentrate can go straight to the regrinding circuit. So we are skipping a dewatering stage. And on top of that we have a much simpler classification process when it is required, and often it is not required. These are simplifying the circuit a lot. And on top of that, treating that water from dewatering means additional equipment and additional cost and footprint in the plant.”
So where does Metso see the greatest initial potential? The demo plant is at a relatively small copper operation compared to the very large copper mines. Rinne:“ But we definitely wanted to test it with copper because if you look at the market potential for CPF, more than half of that will be for copper, as this is where the largest tonnages are processed and where the largest grinding circuits operate.”
Carvalho:“ In our opinion, if the biggest mines – both greenfield and brownfield- don’ t start using coarse particle flotation soon, they will not be in operation in the future, due to factors like low grades, comminution energy costs, limited space availability and water shortages, and crucially a move away from wet tailings storage.”
Where is Sampo to be installed to maximise results for the customer? Rinne:“ If the customers are looking for a big increase in plant capacity, then it must be in the beginning of the flowsheet. If they are looking to increase plant recovery or throughput, then it’ s in the end of the flowsheet for scavenging of tailings. Because tailings duty is the easier application at this stage, coarse particle flotation will first happen in plant capacity related use, and gangue rejection will happen in the medium term. It will also take time for the market to fully accept coarse flotation and to better understand the advantages but also the risks.”
Rinne and Carvalho said that in a tailings application, in most cases it will be possible to push more throughput as you can grind coarser with the existing grinding capacity. Some particles will be lost in normal flotation because there is insufficient liberation for recovery to occur in the main flotation circuit, but then in the scavenger or tailings stream Sampo will recover the remaining metal. Rinne:“ In most cases we will still be able to achieve at least 5-10 % capacity increase. In the industry already today, when the copper prices are high, mines already make more money by increasing throughput and decreasing recovery so there’ s a lot of opportunity for coarse flotation in these situations.”
42 International Mining | OCTOBER 2026