FLOTATION methods . This frothless system allows for stable and froth flotation , enhanced gangue rejection , and quicker kinetics – pushing the boundaries on concentrate grade , recovery , and throughput well beyond the performance of conventional open tank systems .
Christodoulou told IM : “ The RFC commercialisation journey is going very well – we just completed a full scale test project at a copper mine in Poland where we were testing a full scale RFC850 . The main purpose of this was to see the scale up and if we would get the same results as we had at lab and pilot scale . I am happy to report we have seen this , if anything there has been a slight improvement when scaling up to the larger size unit .”
Plots of the copper recovery versus flotation time were generated to compare continuous operation of the RFC850 to the batch operation of the pilot RFC100 unit . These initial plots showed that although the RFC850 was treating unreagentised feed the performance of the fullscale machine was matching that of the pilot machine . Copper recoveries ranging from 15 % to 35 % in a single pass were achieved with retention times ranging from 26 seconds to 45 seconds .
Once a baseline of performance was established a later test campaign was executed at operating conditions such that recoveries were improved . Feed to the industrial machine was reagentised for this campaign . Again , recovery versus retention times were plotted . Results from this campaign showed that the full-scale RFC outperformed the pilot batch runs in terms of recoveries achieved at comparable retention times . Copper recoveries ranging from 20 % to 54 % in a single pass were achieved at residence times ranging between 43 and 60 seconds utilising the RFC-850 . Results from the test campaigns showed that the industrial scale equipment performed equally well when compared to the pilot scale equipment . Upgrade ratios for the industrial machine treating scavenger feed material ranged from 2.6 to 5.2 , producing concentrate grades ranging from 4 to 12 % Cu in a single pass .
He added that FLS has secured a purchase order for industrial RFC850 units in North America in an industrial minerals applications , with commissioning expected in early 2025 following completion of fabrication in early November 2024 .
With the RFC , lamella plates come into play – which , due to the Boycott effect , allow the bubbly mixture to segregate very efficiently , preventing any loss of air bubbles to underflow . This enhanced segregation capability allows the RFC to operate at a very high air fraction and control what is coming out of the overflow in terms of volumetric flow rate . With the application of wash
Inside each WEMCO II cell is a newly designed rotordisperser system that delivers intense mixing and aeration
water , you can displace any material that is coming up in the remaining water present in the bubbly mixture to maximise control of the grade and achieve a very high quality product coming out of the overflow .
Finally , a note on another FLS technoogy , CoarseAIR , which is a low turbulence , aerated fluidised bed separator combined with lamella plates based on the REFLUX™ Classifier . The technology is able to float larger particle sizes ( up to about 650 micron ) enabling an increase in target grind size and offering significant sustainability and process benefits . It provides excellent efficiency through improved resource utilisation – not only in terms of air , water and energy but of the mineral resource itself .
Christodoulou : “ CoarseAIR is developing quite well , we are doing a lot of lab scale testing at our Salt Lake City Technology Center and have seen very good performance in an industrial mineral application and the technology has a lot of potential in areas like phosphate and potash . Based on that we expect to start site trials at pilot scale in early 2025 . We have also have run a couple of significant lab test programs in copper where we are seeing good recoveries of coarse particles that are available in the feed , achieving a low tailings grade with good upgrade ratios . So from a lab perspective we are seeing the results that we would have expected .”
He added on commercialisation that the design of the larger size CoarseAIR machines is virtually complete , so we are now talking to customers about a suitable site for pilot or small industrial scale testing in a partnership arrangement . The most likely initial and lowest risk application for CoarseAIR is in tailings retreatment to scavenge coarse particles lost during conventional flotation . “ But the biggest bang for your buck would be in a split flotation circuit where would have fines reporting to
conventional flotation or RFC and the coarse particles reporting to CoarseAIR . Then you can start looking at more power savings in the grinding circuit plus quicker water recoveries and better performance in the finer circuit . Plus less overgrinding of material and therefore less ultrafines .”
But what differentiates it to other CPF options ? “ CoarseAIR is based on the REFLUX Classifer , which already has quite a large installed base in various commodities . The inclusion of the inclined channels or lamella plates gives a high tolerance to the presence of any fine material that would ordinarily by hydraulically misplaced to the overflow . So we are seeing better upgrade ratios than other CPF options in the market .”
NovaCell reaches pilot stage with Capstone after Pinto Valley study
The NovaCell is a novel froth flotation machine , exclusively available from Australiaheadquartered Jord International , which was invented by Laureate Professor Graeme Jameson . Its value lies in that it recovers valuable particles over a wider particle size range . Thus , coarse and fine valuable particles that were previously lost to tailings using traditional technologies , such as mechanically agitated flotation cells , can now be recovered by one machine , potentially increasing the plant production .
Targeting coarse particle recovery in the flotation circuit also allows for greater flexibility in the comminution circuit , potentially reducing the specific energy consumption , the greenhouse gas ( GHG ) emissions per tonne of valuable component , and improving the dewatering rates in mineral processing circuits . To investigate these NovaCell benefits , samples from an existing copper operation were studied under laboratory conditions . In this case study , the response of plant feed and tailings material from
OCTOBER 2024 | International Mining