Tuesday, 20 April 2021

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.


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.


  1. Many Thx to the organizers! And to my fellow panelists. Excellent discussion and insights! And to all those that attended!

    Peter Radziszewski

    1. Many thanks to you Peter. You were a star, and I knew you would be when I invited you to the panel. I look forward now to your presentation at Sustainable Minerals '21

  2. Day 2 UP DATE by Barry-- being a participant, let me add my own comments(I can never match you, Barry--mine are of "60s vintage-1)All kudos and hearty compliments to keynote speakers, other speakers, and to the participants of group discussions; of course more to all the participants of such an exceptional international seminar--so much valued by all mineral engineers across the world(like spectators clapping during the cricket match at Kolkatta stadium--lifts the spirits of Indian players)--thank you participants and sponsors--again and again.
     MACHINE DESIGN-so well presented and I wish such a lecture had come 50 years ago--better late than never--so much to learn and use by the young generation.Yes, simulation is really the "name of the future" for the mineral industry. Let me give my own experience as a consultant to McNally Bharat (earlier (McNally Pittsburgh), an engineering firm near Dhanbad--Barry, I am sure you are familiar.The then M.D.., Mr. Srinivas Singh, respected my idea and we visited a CSIR Lab (Central Mechanical and Engineering-Institute-CMERI). Those engineers never saw a ball mill--will not go into detail. CMERI did finite element analysis (Greek and Latin to TC)and reduced the weight of the mill --the cost of manufacturing came down and the company got the maximum share of the market due to less cost.I have been personally wondering why RPG s did not come more into plants--we introduced in the late '70s in a phosphate plant which gave the company(Rajasthan Rock Phosphate Ltd) huge savings in space/capital and operating costs. Iron ore plants should have tried by now--maybe lack of marketing strategies!
    I respect the views of all on various mills and MEI also ran some Blogs earlier on sag mills etc.Keep the discussions going and one day some young fellow(s) will pull out rabbits from the hat--in corona, it is the hair growing more!)
    The word "tailing" should disappear from our mineral engineering dictionary. Just let us pause and think--the cost of producing each particle (mining/crushing/grinding -etc) before beneficiation is the same--Why we never think of this?--then we have beneficiation--concentrate and tailings. In fact, many plants do not recover many minerals and elements from tailings--for any suggestion, the standard answer is "markets price/economics__too many Management Gurus not allowing us to think differently (sensibly).For me, the challenge is to grind to sizes till all values are liberated(let them be in extreme fine size), then dry beneficiation and make the value out of each grain.Innovate to change surface characteristics of wanted and unwanted particles, maybe by spraying something(innovation) and come out with a process to separate.For TC, first, make it technically feasible and then economically viable--we are doing in solar/vaccine/mission to Mars-
    -2)Now, what Barry wrote on Dr.Lynch and Rao--to be honest, I had no clue while collecting the data--I did one variable at a time--no"design of experiments"--just collect accurate data, the teaching of Dr.Lynch.
    A lot of credit to Mt Isa Mines, Prof.White, U.Q. Dr.Lynch did the real thinking  (vision to see the implication and application). I left J.K. in 1967 and Dr.Lynch and so many made that model so useful--.The credit mainly belongs to. Dr. Lynch and I am happy and feel blessed to bask in the reflected glory of Dr.Lynch's efforts.
    Long comment--but the contents of the second day took me to a different planet.
     Wish you all the best and looking forward to the third day.


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