FLOTATION TECHNOLOGY
FLSmidth also recently launched its ( see IM October ' 20 , pp 58-59 for full article ) revolutionary REFLUX™ Flotation Cell ( RFC™ ) which is being developed together with the University of Newcastle . Lamella plates allow the bubbly mixture to segregate very efficiently , preventing any loss of air bubbles to underflow . This enhanced segregation capability allows operation at a very high air fraction and to control what is coming out of the overflow in terms of volumetric flow rate maximising control of the grade to achieve a very high quality product
much deeper . Then in the WEMCO cells you hit the material with energy ( over twice as much ), to recover all the fines and coarse that were not recovered by the nextSTEP .” nextSTEP is also in use at a copper mine in Peru where some of the WEMCO cells in the top of the row were retrofitted with nextSTEP . With the same throughput they are getting 1-2 % higher recovery .
An important new WEMCO cell only project is a copper project in DRC . This is a special design with almost 300 m of flotation cells because the ore is mainly copper oxide requiring a lot of residence time and conditioning . They chose 100 % standard selfaspirated Wemco cells due to the remoteness of the project so they wanted a design that was robust and easy to maintain . It doesn ’ t need a blower and the system adjusts the air itself .
Finally , on the adjustable radial launder and froth crowder systems Lelinski added : “ In my opinion this is where we can get the biggest advantages for customers for lowest cost – in the froth phase at the end of the row . Where you have a large cell with radial launders , we put crowders in between the launders which are up and down adjustable . The crowders can squeeze the material quickly into the launder at the end of the row where the froth is getting stagnant . We have applied this at another plant in Peru , which has 250 m 3 and 130 m 3 WEMCO cells and they put it on approximately 75 % of each row . Other plants in South America and Asia are also installing these systems .”
On another note , FLSmidth just acquired KnowledgeScape , a global leader in digital optimisation solutions for the mineral processing industry ; it means that FLSmidth will have ownership of a portfolio of expert control solutions and advanced sensor technologies for automating , optimising and increasing the reliability of mineral processing circuits . The combination of KnowledgeScape offerings and FLSmidth ’ s existing digital solutions has the potential to position it as the leading supplier of optimisation solutions in the minerals processing industry .
In addition to these advancements
FLSmidth has invested in development of novel flotation technologies which are expected to have major impacts on the flotation circuits of the future . The new REFLUX™ flotation cell ( see left ) is an example of the steps being taken to compliment and expand the company ’ s flotation portfolio and further its Mission Zero objectives .
Best of both worlds
The creation of Metso Outotec was only finalised in July 2020 , but this article was an opportune time for IM to catch up with Paul Sohlberg , VP Separation business line at the new company . He comments : “ Overall , just looking at the Separation business line , which includes flotation , thickening and clarifying as well as automation and digital solutions , the Metso Outotec combination is very complementary in terms of technologies , geographies , products and customer segments . Just looking at flotation , there are some overlaps , but I think from a total business perspective these overlaps are minor . Of course , the Outotec TankCell has had tremendous success in the market and has been a technology leader for a long time . At the same time Metso and its RCS solution has been doing a great job as well and they also bring experience in column flotation – the Microcel line – to the combined offering .”
Sohlberg said that where there are overlaps , these are being looked at as part of the overall portfolio review which certainly for the highest business volume product areas is planned to be completed by end-2020 . “ The merger brought together two great players , so we are putting everything on the table , approaching the process with an open mind . This means comparing what is the optimum combined
offering from a product point of view but also from a supply chain and engineering practices point of view . And of course , getting feedback from our customers is also part of it .”
Looking in more detail , on the Metso side they had both self-aspirating ( DR ) and forced air technologies ( RCS with DV mechanism ) whereas Outotec only offered forced air ( TankCell with FloatForce mechanism ) – so Sohlberg confirmed that the review is looking at the RCS and the TankCell lines side by side and keeping the “ best of both worlds ” – but adding that the product lines were segmented slightly differently in terms of sizes and had a different market focus in terms of types of customer and application . Metso ’ s self-aspirated technology for example was only supplied on smaller cells and focussed on selected markets .
Another area to look at is froth cameras and imaging . The Metso VisioFroth solution has been highly successful , and on the Outotec side is the FrothSense solution . But both work in slightly different ways and both have their attributes . “ Making sure we take the best of both offerings forward here is another important part of the ongoing review ,” Sohlberg stated .
Sohlberg added that upgrades and modernisations of existing cells would continue to be an important part of the business - the former Outotec and now Metso Outotec upgrades , such as FloatForce mechanism and froth management upgrades are available as a retrofit for any brand of flotation cell including older Outotec and Metso cells as well as competitor designs . Upgrades can include for example , the rotor , stator and stator stand and wear plate and parts for the tank bottom . Solutions vary from hardware and installation supervision to complete turnkey solution including installation , commissioning and ramp up until measuring and validating results . A FloatForce upgrade can enhance pumping performance and energy efficiency , improve air dispersion , improve the recovery of coarser particles without compromising fine particle recovery and increase wear life . Froth management upgrades optimise froth recovery and helps to achieve grade and recovery targets . He told IM : “ Retrofits and upgrades are a key part of our services offering in flotation , that said we look at each project individually to determine what is the best way to increase performance in that specific application .”
As an example in March 2016 , at the Chapada mine in Brazil ( then Yamana Gold and now part of Lundin Mining ), Outotec began a turn-key retrofit of 10 existing 160 m ³ non-Outotec flotation cells with Outotec TankCell ® and FloatForce ® technology . The existing circuit offered opportunity for improvement in flotation performance in terms of copper and gold recovery , as well as in availability due to heavy sanding and substantial maintenance requirements due to heavy corrosion . The upgrade brought greater stability and control of flotation cells allowing for increased process optimisation and significantly
24 International Mining | NOVEMBER / DECEMBER 2020