Monday, 15 February 2021

Keys to Best Practice Comminution

This will be the title of a keynote presentation at Comminution '21, to be presented by John Starkey of conference sponsor Starkey & Associates Inc, Canada. John has worked for 15 years in operating mineral processing plants, 15 years in engineering companies designing concentrators, and 30 years as a Consulting Engineer. He invented the SPI, and SAGDesign tests, and the lab mills required to do these tests.  

John Starkey (right) and his wife Donna, at Comminution '18
with Erik Spiller of Colorado School of Mines

John says that there are three reasons for his keynote. For operators to manage good operations; for designers to produce workable designs; and for educators to provide useful education for mineral process engineers.

In all cases, he considers that an understanding of the transfer size (T80) to the ball mill is critical to achieve best economics in a SAG mill grinding plant. T80 is important to operators because when SAG energy and Bond Ball Mill Work Index on SAG ground ore are measured, accurate prediction of future throughput in any SAG circuit is possible. Without the plant T80, it can take many months to figure out how to correct what is really a SAG mill grinding problem, because that problem is hidden if the T80 is not measured.

Best practice comminution means running a SAG mill at its best conditions, and 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, production shortfalls result and operating costs are high. Extra SAG mill capacity is a bonus while lack of capacity is a disaster.

John will show how to design workable grinding circuits on the same ore, using either single stage SAG milling, SAB grinding, SABC grinding, or HPGR pre-crushing followed by ball milling. There are many ways to set up a SAG plant and future expansion should always be considered at the design stage. This opportunity is often overlooked because the designer did not understand the options available.

The provisional programme for Comminution '21 will be announced very shortly.



  1. Barry,
    I read the Blog in detail. It made me very happy that you are planning to start the engine of our profession to "move" to reach the vision you always had for Mineral Engineering.
    My compliments to John Starkey for the topic he selected for the keynote presentation--the key words he used are "education," are so important. Lack of such integration has been the root cause for all----
    Regards to all.

    1. Since the topic is comminution, I already made my comments; now more are coming to my mind on "comminution" We generally look at comminution and the unit that does the comminution--may it be ball mill/sag/semi-autogenous/ etc with all sizes and different discharge systems. Yes mills consume maximum energy and across the world, major energy is spent on "comminution--size reduction--may be road-making, etc)
      I get a feeling (maybe wrong} that many think that cyclone is a "stupid, static unit" which does not make noise/and most flexible in operation depending on the design and operating variables (Lynch and Rao can take some pride in understanding cyclones in a more respectable manner}
      For a conventional mineral engineer, Comminution" should include cyclone.
      The total operations starting from jaw crusher (or something else} to tailings and concentrate are akin to a human system. In the human system, we have different organs working in harmony but the "heart" is very important. For me "comminution" is like the heart in the human body.
      In summary I want to convey that both the Title and Keynote topic selected, as I commented earlier is of most vital and of paramount importance.
      Let me compliment all involved.
      Hyderabad, India

    2. Your comment on hydrocyclones is interesting TC as in my conversation with Prof. Lynch (blog of 11th August 2014) he said "the way they (cyclones) are used now is an absolute nonsense, with circulating loads in some cases of well above 200%. The future is high frequency screens..... it is very clear that these screens are so much better than hydrocyclones."


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