SEPARATION & CLASSIFICATION
CiDRA P29 mineral loaded collection media
Separation step changes
Paul Moore reviews some innovation areas in mineral separation and classification , including a potentially revolutionary flotation alternative , the latest on cyclone technology plus dry magnetic separation
Mineral processing has evolved hugely in recent years , enabling mining companies to tackle lower grades and more challenging ores . But a lot of this has been achieved by increasing efficiencies through more refined designs of what are fundamentally the same basic processes that have been around for many decades and in some cases over a century , whether that be crushing , flotation , thickening or filtration . It isn ’ t often that you see a real step change in the mineral processing industry in terms of a completely novel solution .
But CiDRA Minerals looks to have done that with its novel P29 Technology™ platform , named after 29 , the atomic number for copper , as it is in the copper mining industry where much of its initial potential and focus . The technology was recently referenced in an article from McKinsey titled ‘ Bridging the copper supply gap ’ that stated : “ The system is based on the development of an innovative new material that acts as a so-called copper sponge , attracting and holding mineralised particles based on the same hydrophobic properties that cause them to float during flotation . Unlike systems that take effect further downstream , grind-circuit roughing offers the possibility of directly reducing the recirculating load in ball mills , increasing ball mill throughput by as much as 20 % at a constant grind size .” It adds “ Operators will need to decide how to take the dividend of increased ball mill efficiency , which could be seen as an opportunity either to drive throughput or to reduce grind size and increase recoveries at a constant throughput . The optimal choice will depend on the properties of the ore body and the existing configuration of the processing plant . However , even with allowances for further cleaning of the concentrate pulled by P29 and consideration of other common system bottlenecks , grind-circuit roughing could add 1.2 million to 4.6 million metric tons of annual copper production by 2032 .”
So how does it work in detail ? The technology , methods and potential are detailed in a new white paper just posted by CiDRA . IM also spoke to Bob Maron , CiDRA Chief Commercial Officer for more detail on the technology and its potential : “ It started out with us looking for an alternative to conventional flotation . How could we capture particles better than the current flotation technology with bubbles , which has been around for over 100 years ? It involves the use of a media as a substrate . We started with spheres and it has evolved into using an open cell polyurethane foam in 12.5 mm cubes . An engineered hydrophobic coating is applied to the substrate enabling it to attract hydrophobic particles in the same way that a bubble does . However , it does that much more strongly than a bubble ; it doesn ’ t burst like a bubble ; and because it is open cell foam , the amount of surface area per unit volume is much higher . The substrate foam we use is in the form of small cubes which is mixed with the ore slurry in a rotating drum . The slurry penetrates around and through the foam and contacts the foam surface and the reagent chemical , similar to that used in flotation ,
attracts the hydrophobic particles .”
Maron says it is also very different to dense media separation which still uses an air-water mixture – P29 has no separate air ( or water ) input – just the coated foam media and the slurry . “ By using this media substrate with an engineered coating , we can control the attraction and the holding of the particles separately from its transport and release . This is in contrast to a flotation bubble that has to attract the particle and then transport it without losing it , plus finally release it . This is all subject to the fragility of the air bubble . The attraction forces are not that great , and the bubble can break . Particles can fall off plus the buoyancy of the bubble is limited if it is overloaded with particles . The flotation process also suffers from hydraulic entrainment of free gangue particles which can have a significant impact on downstream processing requirements . P29 eliminates all these flotation limitations . This is because the attraction force is extremely strong which also means you can transport it easily without losing those particles . The final separation is done via a biodegradable non-ionic surfactant , which breaks the hydrophobic attraction . P29 provides the ability to use engineering levers to control and optimise each step of the mineral separation process independently . It can also recover both fine and coarse particles , whereas in flotation different cell types are being used for these separate duties .”
Given the global demand for copper and the push towards ‘ greener minerals ,’ the higher value proposition currently for P29 is to recover very coarse particles – much coarser than can be currently recovered via flotation , up to 3 mm . So , while the technology has the potential to replace flotation in theory , CiDRA Minerals is starting by addressing the most immediate application that can bring the highest value to its customers and so has developed a novel mineral separation solution called Grind Circuit Rougher™ ( GCR ) which leverages the P29 Technology™ platform ( P29 ).
This can take a significant stream of coarse particles from the hydrocyclone underflow that would normally go back to the ball mill and recover those particles that have some valuable mineral content , down to very low copper grades . The rest of that gangue can then be rejected , and those copper bearing particles can go through a light regrind and then onto final concentrate . You are saving volume of material going through the mill and therefore making significant energy savings . The 10-20 % of the material you are taking out of the mill feed can then be replaced by fresh feed . It also means that the stream that is going to flotation is a bit finer , so the flotation
12 International Mining | MAY 2023