Wednesday, 21 April 2021

Comminution '21 Day 3 update

Wednesday 21st April

Day 3 of Comminution '21 was devoted entirely to High Pressure Grinding Rolls (HPGR) and SAG Mills (see footnote), and opened with a keynote lecture from John Starkey, of Starkey & Associates, Canada, who described how to get the best performance possible from your existing machines in order to keep down operating costs.

This was an excellent presentation, very clear and concise, which should be seen by everyone involved with SAG milling. John began by saying that the SAG mill is the heart and soul of many mineral processing plants and every engineer should know how to design a SAG mill.

He was critical of JK software for design, although he felt it excellent for optimisation, and it is a shame that we have no representation from JKMRC at the conference as this could have led to an interesting discussion.

Questions started to flow into the online discussion only 15 minutes into the presentation, and I must say that we have been very pleased by the interaction between delegates and presenters via the online text facility. Although there are obvious difficulties due to time zones, questions and replies to all presentations have been coming in not only during, but also well after the presentations, and discussion can go on for another 6 months, so we do ask the presenters to dip in occasionally.

Starkey & Associates are regular sponsors and exhibitors at the comminution series, and I visited their booth during the first break, which followed two innovative presentations from Australia on hybrid comminution machines and circuits, the presentation from Mike Daniels on Eccentric High Pressure Centrifugal Comminution being the subject of a recent article in International Mining

This week has been my first experience of a virtual exhibition, and I was initially sceptical, but I have found it to be very relaxing and rewarding to "stroll" around the exhibits and call in at the booths to browse the literature on display. The company representatives are clearly displayed in the booth, and if they are not actually within the booth at any one time, they can easily be contacted via the meeting hub. The only drawback of a virtual booth, of course, is that there is no working equipment to view.

After the 6 morning presentations on HPGR, the afternoon session contained 11 presentations on SAG milling, including another presentation by John Starkey, and one from another conference sponsor ME Elecmetal, USA, Amit Saxena describing the optimisation of discharge flow efficiency in a SAG Mill.

Another great day ends, and we look forward to tomorrow's sessions on Stirred Mills and Milling 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. I agree with Barry on the third-day proceedings--presentations and discussions around HPGR and SAG Mills.
    Let me take a "more practical view" apart from the various aspects we may have discussed on any mill.
    Let me present my views from a practical perspective.
    The ore characteristics and the liberation characteristics vary--many times the size range and minimum assay(two parameters))become constraints depending on the subsequent metallurgical process--say in the case of iron ores--lumps for B.F.. and something else for sinter and /different for pellet plant. Even a single metal producer will have all of them. Many times they buy the raw ore from different sources whose characteristics keep varying from day to day--PLEASE NOTE that I am speaking from the Indian context
    So how does a mineral engineer operating his beneficiation circuits meet the "stringent needs " of these consumers (metallurgists); yes, I pity the metallurgist also to some extent.
    For copper ores,--as we go down in depth or horizontally--the ore may become malachite rich though the mine was opened for chalcopyrite.
    With the above, what type of mill one should select so that ROI is within a given time frame.
    Tumbling mills.HPGR and sag have their own performance characteristics. J.K.'s name came and so I will not touch that aspect--as Barry said, let that be for another day with J.K being there.
    Now, THE MOST critical question is "manufacturing of these types of mills"--a lot of engineering, specifications/. a lot of R&D, then heavy capital investment, and so on apart from marketing. How can one Company be sure of how many mills they would be able to sell globally per year--offices, expertise in marketing--very complex.
    I have been involved and have been interacting with equipment manufacturers and operating people---
    So a "holistic view" is a must--maybe a summit between all stakeholders at a global level to at least discuss--. If we discuss climate change, WHY NOT MINERAL EXPLOITATION.
    Centrifugal Comminution very exciting and hope it helps to produce at least pellet feed with minimum energy consumption at high throughputs--is it a dry or wet process?
    Going great Barry and Team, I am definitely reenergized. I wish I am spending the evenings with the participants.
    Best to all.

  2. I agree with Professor Rao's above comments with my understanding that we must adopt world best technological know how whatever is available for zero waste mining and utilizing 100% available resources keeping in view of intergeneration equity and sustainable development. The Government Policy documents must be implement in true sprit to safeguard mother earth from unscientific, unsustainable exploitation.


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