Comminution '21 Day 2 update

Tuesday 20th April

What novel machines are to be found in the future? In the first presentation of the day, Dr. Paul Cleary, of Australia's CSIRO, described in his keynote lecture the Virtual Communition Machine, an approach which is already being used to drive the rapid evolution of comminution machine design. The presentation contained truly amazing animations of simulated comminution in various machines, which allow new ideas to be trialled in a virtual framework at a fraction of traditional cost and time. The VCM can provide much greater mechanistic insight, which can improve and accelerate development of new machines, as well as machine scale-up.

Paul at Comminution '18 with Mintek's Elizma Ford,
who will be presenting a paper on Thursday

Paul's keynote was the first paper in Modelling and Simulation, the theme of today's long technical session (see footnote). Progress in computational methods have come on at a tremendous pace in the last half century so it was a privilege to have one of the early pioneers of mathematical modelling in mineral processing, Prof. T.C. Rao with us at the conference. Prof. Rao obtained his Ph.D degree under the guidance of the JKMRC's first Director, Prof. Alban Lynch, in 1965, working on the characteristics of hydrocyclones. They published their work on hydrocyclones in a number of seminal papers, and the models are still valid today, being used in many hydrocyclone manufacturers' performance curves. 

Profs. Rao and Lynch reunited in Brisbane in 2016

Prof Lynch, who is now 91, intended to be with us today, but unfortunately was unable to do so but sent his best wishes to all at the conference. The last time Alban Lynch and Paul Cleary met at an MEI Conference was 20 years ago, at Comminution '01, and I'm sure that both Alban and TC would have loved to have spent time with Paul at this year's event, as Paul is also a pioneer of a technique which they would not have heard of in the early 1970s, but was introduced to us all at Comminution '01- DEM Modelling, the subject of a number of papers today. And they would certainly not have heard of Positron Emission Particle Tracking (PEPT) which has become a widely used tool in recent years, and two presentations from South Africa showed how PEPT has been used to validate DEM Models for tumbling mills and stirred mills.

"What will comminution circuits look like in 2050?" was the theme of the mid-day panel discussion, chaired by Mike Battersby of Maelgwyn Mineral Services Ltd, UK, and Chairman of CEEC. Giving their views were Grant Ballantyne (Australia), Joe Pease (Australia), Alex Potapov (USA), Peter Radziszewski (Canada), Paul Shelley (Australia) and Weigo Xie (USA).

There was a wide ranging discussion, but a general consensus was that coarse rejection of gangue prior to comminution, and separation at as coarse a size as possible, concomitant with recovery, would be needed to reduce energy and water consumption. It was also felt that there would be more emphasis on dry grinding and processing, although there are environmental and health concerns associated with this. Alternative technologies such as high voltage fragmentation and microwave heating, to weaken grain boundaries, might also be used but although good work at small scale has been carried out they may not be able to be fully utilised at high throughputs.

Secondary mining and processing was also touched on, and Grant Ballantyne felt that there would be much more emphasis on processing old tailings in the future, with reduced comminution requirements.

Not surprisingly there was much discussion on simulation and the use of artificial intelligence and Mike Battersby commented on Paul Cleary's keynote this morning, endorsing my opinion of the superb simulations showing how far we have come over the last couple of decades.

Grinding is evolving and changing fast, with innovations in high pressure grinding rolls and stirred mills threatening to make the tumbling mill, which has been a stalwart for well over a century, obsolete. At the panel discussion at Comminution '14 Tim Napier-Munn said that in terms of the future of comminution "we really have to get rid of tumbling mills". Are rod mills now finally obsolete? Ball mills would have dominated comminution conferences little over a decade ago, but they are mentioned only rarely now.

This question came up at the very end of today's panel discussion, and I would have liked to have heard more from the panel, who felt that tumbling mills would still play a role, but that they would be more efficient, particularly regarding the associated classification.

SAG mills are still of major importance, but I asked the question at Comminution ’12 whether ball mills would play a significant role in comminution circuits, or would they be superseded by SAG mills. Chris Rule, yesterday's keynote speaker, felt at that time that rod mills would play an insignificant role, as they are severely limited in terms of size, and ball mills may play a diminishing role as the upper feed size range of stirred mills increases. 

With HPGR grinding finer and stirred mills taking coarser feeds this is open to discussion, and we will no doubt hear more of this in the next couple of days, tomorrows sessions covering HPGR and SAG Mills, and Thursday Stirred Mills and Grinding Circuits.

@barrywills

By clicking on any presentation in the programme, you will be able to see the abstract and the biographical details of the presenter. All presentations will be available for 6 months, so you can register for the event at any time.