FLOTATION TECHNOLOGY
elsewhere, and I can see that it’ s been very exciting for a lot of our customers. Because we need very little, if any, classification, we don’ t need a separate circuit for it, and more importantly, we use much less water. Metso’ s technology brings operational flexibility- for example, an incursion of fines is not an issue with our technology. It’ s perfectly fine to have the fines included in there and it can actually float them as well. Our CPF also fits extremely well into new flowsheets because it’ s all about reducing the energy that we’ re spending grinding gangue- it goes very well with our Vertimill technology.”
Metso now has a demonstration plant at an industrial level. The 25 t / h CPF demo plant will be running any day now on a tailings stream at a copper operation in South America. The product will be released in H1 2026, when the technology will also be formally named. Test work has been conducted in both gangue rejection and scavenging applications, showing good promise in both duties at laboratory and pilot scales. It is the subject of a paper Metso is presenting at the forthcoming Flotation 2025 conference in Cape Town, November 17-20 which is organised by MEI Conferences.
The Concorde Cell is also the subject of two papers Metso is presenting at the conference. The first subject study being presented focuses on optimising the performance of the Concorde technology on reverse flotation for iron ore, from laboratory scale experiments through pilot-scale trials, including a detailed comparison of data across scales to evaluate process scalability and consistency. The research aims to maximise iron recovery and concentrate grade while minimising silica and other gangue minerals. The paper follows Mesabi Metallics awarding Metso an order in 2024 for beneficiation plant equipment for their Direct-Reduction( DR) grade iron ore plant in Nashwauk, Minnesota. The Mesabi plant helps ensure supply chain security for DR grade pellets in the United States while supporting the decarbonisation of steel production.
“ The Concorde Cell flotation cells, a crucial component of the equipment delivery, are vital for ensuring flotation performance in Nashwauk’ s iron ore application. These high-intensity flotation cells, part of the Metso Plus, open in a new window offering, allowing operations to improve fine and ultrafine particle selectivity,” said Martin Nevens, Director, Minerals Sales, North and Central America at Metso.
The last Metso paper concerns a Concorde Cell which was commissioned and taken into operation at Boliden Kevitsa Cu-Ni PGM concentrator in January 2025. An example of the measured metallurgical performance of the cell showed that from the Ni rougher concentrate 80 % Ni recovery was achieved at over 1.6 Ni enrichment ratio and when the selectivity was prioritised over 2.5 Ni enrichment ratio was measured at over 65 % Ni recovery. Overall, when the Ni rougher concentrate was processed with the cell most of the concentrate samples contained over 10 % Ni and some even over 14 % Ni.
Finally, in October 2025, Metso is opening a new dedicated flotation area in the labs at its Research Centre in Pori, Finland. At this main R & D base for flotation, there will be two Concorde Cells as well as a CPF cell. These will increase Metso’ s capacity to run novel flotation technology test work at lab scale and also aid in new flowsheet development for customers.
FLS WEMCO II & other flotation tech gathers momentum
WEMCO ® flotation cell technology was first developed in the 1930s, updated in 1968 and has been the same ever since. Although this robust and impressive design has been a technology standard for many decades, FLS has set out to improve the original design with a new rotor and stator configuration which improve hydrodynamic, kinetic, and metallurgical performance. Guiding principles were investigated and generated with FLS’ s forced air flotation offering, the nextSTEP™ flotation cell, and carried over into the improvement of the new design, the WEMCO ® II. Principles developed at bench and pilot scale were applied to prototype industrial scale units, which were compared with existing traditional WEMCO installations in mines across North and South America.
Trials of a WEMCO II 250 m 3 cell installed in a Cu-Mo rougher application in a South American concentrator compared performance to a standard WEMCO. Improvement was measured from comparative data including intake air velocity, superficial gas velocity, retention time and Peclet number comparison from RTD testing, froth stability, and metallurgical performance.
Ian Coltrin, FLS Product Line Manager, Flotation told IM:“ This past year has been big for the WEMCO II, as we have been able to install a few units in some of our 250 cubic metre size round tank cells in a South American concentrator. And this really afforded us the opportunity to really see the impact of a WEMCO II, because the site that we have installed it at is very well maintained, plus the slurry is consistently analysed. They have online analysers, and they do lab tests frequently and so they can see any differences, and we were able to really confirm what we have been kind of skirting around for the last few years installing in the smaller square cells. We had the opportunity to install it on the second from the first in a 250 cubic metre cell- there are nine cells in this row and there are six rows in total. So this is a huge concentrator. The tonnage of the entire site is about 390,000 t / d.”
FLS was able to do a row to row comparison between the row that it installed units on versus another comparable row in that concentrator.“ And when we did this row to row comparison, we didn’ t see too much of a difference. However, when we did a cell to cell comparison, comparing the WEMCO II in the second position in that row versus the cell in the second position of the other row, we saw a huge difference in recovery and this was great because this is a rougher application and so recovery is your main goal. When we compared recoveries between the two cells, the WEMCO II gave us an 8.5 % advantage over the standard WEMCO on average. It was tested over several data points. We removed any outliers in any type of upset conditions in the entire process of the plant to make sure that when we’ re comparing point to point, they really are comparable. So now the site is excited to move forward, especially their concentrator team which is looking at this every day.” The next stage is that on the same row that has the WEMCO II in it, FLS is going to retrofit all those cells and redo the row to row analysis.
Dariusz Lelinski, Global Product Director, Flotation and Reflux Technologies added:“ What we wanted to do is just to simply make sure that it works properly mechanically and then that we have the numbers. We are already installing it at multiple sites globally. And there are two ways to do this. One is the mechanical proof and we had WEMCO II installed in a rectangular cell in North America where for a year there was no practically no wear. So we were then ready for the large concentrator install in South America to prove the recovery. In North America we are following up also with a row installation. And we are installing at multiple other sites. This really is the tipping point. We have a lot of data so we can correlate the improvements with what we’ ve been doing, now we just need to prove that to the rest of the world.”
FLS now has retrofit options with both the WEMCO II for self-aspirated cells and the nextSTEP for forced-air, externally aerated machines. WEMCO II has the potential to retrofit any WEMCO ever made by FLS, which is close to 40,000 around the world. nextSTEP technology is already proven, and has been 10 years on the market with a lot of greenfield installs, but also a lot of retrofits of DORR OLIVER cells and competitor cells. Coltrin:“ We see improvements in three fields with WEMCO II and nextSTEP. One is metallurgy, one is wear life, which is we guarantee at 50 % longer, and lastly is lower power consumption. And it is a
International Mining | OCTOBER 2025