Comminution ’21, one of the minerals industry’s premier conferences, was held on 19th-22nd April 2021. This highly regarded MEI event profiles leading edge research and innovation in crushing, grinding and ultrafine grinding.
The event featured presentations and papers from Australia, Canada, South Africa, Germany, UK, Namibia, Sweden, Belgium, USA, Denmark, Finland, Chile, Brazil, Zambia, France, Ethiopia, Japan, Kazakhstan and more.
Some of the CEEC sponsors presenting and attending included Anglo American, Ausenco, FLSmidth, Glencore Technology, Hudbay Minerals, Magotteaux, ME Elecmetal, Molycop, Newcrest, Swiss Tower Mills and Weir Minerals.
Professor Aubrey Mainza from the University of Cape Town in South Africa gave a terrific conference summary on the final day of the event, noting that the conference had “a wealth of papers from a broad range of topics”.
The first day of the conference focused on energy and ore breakage characterization, as well as alternative comminution technologies. Chris Rule, CEEC Director and Independent Metallurgical Consultant at Seymet, gave the first keynote which examined whether mineral processing operations can make significant energy savings by adopting new technologies and challenging conventional flowsheets.
He expressed the importance of conferences such as Comminution ’21 as they help to disseminate knowledge that is helpful for comminution circuit designers and operators to deconvolute the complex process. He identified water and energy efficiency as key focus areas in terms of technology development and also in terms of how we configure the technologies in existing plants.
The second day focused more on computational modelling and the future of comminution. CSIRO's Dr Paul Cleary gave a keynote talk about the Virtual Comminution Machine (VCM), a full-scale mill simulation containing millions of particles distributed in various particle sizes and shapes that gives realistic predictions of breakage and flows in the mill. Its approach involves a combination of detailed particle scale physics-based modelling and laboratory characterization of material behaviour, particularly for breakage.
Mainza said: “This is really exciting because we can now start using computational tools to design grinding mills with insights on how it can operate from the breakage and flow perspective.”
Michael Battersby, CEEC Chair and Maelgwyn Mineral Services Chairman & Managing Director, chaired a panel discussion on the question ‘What will comminution circuits look like in 2050?’. The panel participants included Joe Pease from Mineralis (also a CEEC Director), Alexander Potapov from ESSS, Peter Radziszewski from Rampart Detection Systems, Weiguo Xie from the University of Minnesota, Grant Ballantyne from Ausenco and Paul Shelley from Molycop.
The panel discussed interesting ideas around energy, water and data-driven decision making, and also looked at how improved modelling capabilities will be influential in future comminution undertakings. They highlighted two areas that will make a significant contribution to future comminution endeavours – dynamic modelling, and the development of advanced sensors that will provide capabilities to allow circuits to operate more efficiently.
Mainza noted that the panel thought there is great potential associated with recycling, as well as many challenges; however, they were quick to point out that the mix of the metal in the feed stock is very difficult to separate.
One technology discussed by the panel was the use of high pressure grinding rolls (HPGRs) in dry grinding circuits with air classification – it was pointed out that HPGRs are operated in conjunction with air classifiers in the cement industry to produce a very fine product, and that can happen in our hard ore environment too. Triboelectric separation was also mentioned; if you use dry grinding processes you can use dry separation methods such as triboelectric separation. Other alternative comminution methods based on micro, electro and nuclear comminution were also discussed by the panel.
The panel touched on digital twinning as an area of interest for the 2050 comminution outlook. Mainza noted that although digital twinning has achieved significant improvements, the panel saw some remaining challenges in matching the real plant given wear prediction.
John Starkey from Starkey & Associates gave a keynote on best practice in comminution. He explained that it is important to run a SAG mill at its best conditions, avoiding overloading, overspeeding and using excessive steel additions, during the design and operating stages of plant setup. When normal limits for these parameters are exceeded in the design stage, it results in production shortfalls and high operating costs. He emphasized that no improvements can be realized from advancement in technology without best practice.
Some new technologies and advances were also revealed at the conference, such as the Geopyörä – a double wheel breakage tester. It is designed to allow mining companies to test several samples at low cost for geometallurgical, comminution design and control applications. Mainza said: “This is a very interesting machine for those who saw the videos, and we are encouraged to look at how we can use this machine and see how we can quicken the testing methodology during our ore characterization tests.”
Another novel comminution device, the eHPCC (Eccentric High Pressure Centrifugal Comminution), was unveiled by CMD Consulting’s Mike Daniel. The shear is a dominant breakage mechanism in this equipment; no media is required, and it promotes preferential liberation. Mainza noted that this could be a very useful piece of equipment, especially as advancements in technology can be very slow in comminution.
There were also some papers on the new generation of HPGR for processing hard rock more efficiently. Mainza said: “It was interesting to see that this technology is continuously being improved, because it has already demonstrated that we can have significant energy savings by applying HPGRs.”
The conference had some papers linking comminution to flotation and other downstream applications. This included a presentation on the new Kalala mill, a grinding device designed to operate inside a flotation cell to increase flotation recovery.
The presentations at the conference were recorded and are available to delegates until October 31st, 2021. Mainza concluded: “This online Comminution conference had a wealth of information. I would encourage all of you to take advantage of the presentations that are still online on the portal.”
CEEC acknowledges MEI and all conference authors, sponsors and contributors for an excellent, informative conference once again, and thanks Aubrey Mainza for his valuable conference summary.