FLOTATION TECHNOLOGY
relatively simple prospect for customers – with WEMCO II retrofits, the only changes will be the hard rotor, disperser, shaft and standpipe.”
Of course, WEMCO II and nextSTEP are still typical conventional cells. They are better what’ s on the market, but there is still room for novel flotation in certain areas and there FLS has two types of equipment. One is the Reflux Flotation Cell( RFC) for fines and the second is coarseAIR™ for coarse particles. With the Reflux Flotation Cell, FLS already has the first few cells running and says it is very close to getting an order for the largest size for a greenfield project concentrator in Central Asia.
Lelinski:“ For cleaner cells and especially column flotation, RFC is the best way to go, and we propose to offer it instead of column or replace a column with much better performance, lower footprint and lower power. Another avenue is to put it on the tails when the losses are in the fine material.”
Coltrin:” There is a lot of work going on around combination of different flotation machines. For your roughers and your cleaners, you can gain benefits by adding this new specialised flotation technology to what’ s already there where you have the WEMCO II and the nextSTEP as the workhorses.”
But there is more to optimisation than the cells themselves. Lelinski:“ There are three stages we look at in a brownfield operation to improve performance. One is going to basics simply looking at what they do – and seeing opportunities for better maintenance, better parts and better overall operation. A second step is go with the retrofits of the conventional technology with the nextSTEP and WEMCO II. And then the third step is novel flotation.”
We then talked about coarseAIR to FLS R & D Manager Himesh Patel. FLS coarseAIR integrates an aerated fluidised bed with the hydrodynamic advantages of the REFLUX Classifier, aiming to improve both mineral recovery and grade.“ The idea is to extend the coarser horizon of particle size that we are treating. So you know in sulphide you are looking at 150 to 200 micron typically so with coarseAIR, most of our testing has been you know 400-to-500-micron range. And now what we are doing is enabling that additional 20-30 % mass to be treated. With coarseAIR, we are not competing with any conventional technology; rather we are adding new rougher opportunities. With new comminution strategies such as HPGR or vertical tower mills as the primary milling method, particles will not be liberated enough for conventional flotation. But when liberated with coarse particle flotation, that liberation level will be achieved. And we have to remember at the same time the filtration and thickening is much better at coarser grind, which also improves the efficiency of the whole flowsheet.”
FLS told IM that coarseAIR is in the pilot unit stage right now, and would not comment on the actual sites but did say that they are all over the globe. So, it’ s very nicely globally distributed.
FLS also discussed froth flotation in phosphate processing where traditional methods can face limitations, particularly where coarser particle fractions often lead to lower recovery and can contain increased impurities. A recent study investigates the application of the innovative coarseAIR coarse particle flotation technology to enhance phosphate recovery. Two distinct samples, representing rougher feed and the combined rougher and cleaner tailings from a phosphate operation, were tested. The testing results demonstrated that the coarseAIR technology significantly exceeded conventional recovery expectations when applied to both the rougher feed and tailings samples. This indicates a strong potential for coarseAIR to improve overall phosphate recovery by effectively capturing valuable phosphate minerals that are typically lost with coarser particles in conventional flotation circuits, offering a pathway towards more efficient and sustainable phosphate production.
FLS also added that today’ s market is all about performance but also having options. Lelinski:“ Still the consensus right now globally is that in a rougher application you must work with conventional machines. The changes are in a cleaner circuit and in tails treatment where the key right with new plants and expansions is offering flexibility of the circuit where you can switch between different options in the same flowsheet – for example the option of a high grade circuit or low grade circuit, where in both cases you have cleaners – all to optimise the performance based on the throughput and the grade of material coming in.” Coltrin added:“ A big upside for FLS is the sheer number of options it has. For a provider of specialist novel flotation technology with a limited offering to the market, you must start with it regardless of whether it is the best offer for a given application. And in our case we have everything. We have two types of conventional cells, two types of novel flotation cells, plus we have columns and moly cells. So we can do a custom fit solution for any application in the world right now which guarantees the best possible performance. Big conventional cells can take anything that you throw at them, changes in the feed, changes in the grade, changes in the P80. Novel flotation is much less flexible so it is currently aimed at bringing the mentioned flowsheet flexibility rather than a whole flowsheet alternative. That said, automation allows you to better adjust for feed changes. With novel flotation there is smaller residence time, and you have to use the recycle to balance the feed. This is the way we use the RFC where you use recycling to make sure that your feed to the RFC is constant all the time, which allows you to get the proper performance.”
A final note on tailings flotation. Lelinski:“ It’ s happening all over the world. When you look at the quality of the old tailing ponds, it’ s much higher very often than primary deposits now being considered. In the past, tails below 1 % copper were good tails. Right now, our primary feed is below 0.5 so most of the tails from a long time ago are easy to process plus are already ground; you don’ t need energy to make them smaller. Second, the head grade is much higher than majority of the feed to existing plant. So, this is a very attractive prospect. Also, we are getting into environmental advantages where we are treating tails then the tails from those tails can be deposited in a much safer way. It’ s typically a very simple plant with cycloning, size separation and flotation.”
Eriez- taking coarse particle flotation into the mainstream
Since at least the 1980s, and driven by lower grades and larger mines, vendors have focused on designing and commercialising larger flotation machines. Eriez argues that while this has certainly improved layout and capital costs, it is generally accepted that flotation kinetics and recovery in the larger units are often not as efficient as their smaller counterparts adding that considering this through the resource stewardship lens, it is not ideal.
Keeping that in mind, Eriez’ product development philosophy is to answer industry’ s call for larger units while simultaneously improving unit performance, and it does this by focusing on engineering first principles like kinetics, fluid dynamics and mass transfer. The first example is the StackCell ® family, a high efficiency two-stage mechanical cell. At the Red Chris coppergold mine in British Columbia, Newmont recently reported that a pair of StackCell 200s at the head of the rougher line is routinely achieving twice the flotation rate as the conventional mechanical cells that make up the balance of the line.
Another example is Eriez’ coarse particle flotation( CPF) machine, the HydroFloat ®, which McKinsey has identified as a key technology platform to increase copper mining efficiency. Since the first generation CPF-130 units were commissioned in copper at Newmont’ s Cadia Valley T3 plant, Eriez has developed larger units such as the CPF- 300 installed at Anglo’ s El Soldado, with a reduced aspect ratio that can handle double the capacity of the first generation. To further
International Mining | OCTOBER 2025