Monday, 22 June 2015

CEEC Medal Award reflects the growing importance of ore sorting

The most attractive way to reduce energy use in comminution is to do as little of it as possible. So said Dr. Rob Morrison, of Australia's JKMRC in his keynote lecture at Physical Separation '15. Rob went on to discuss how both energy and water have begun to become more expensive in real terms and access to minerals, and especially to water where there is competition from growing populations, are becoming limiting factors. In contrast to this bleak picture, we now have access to an expanding range of sensors. Some of these can detect minerals of interest through meters of rock and ever more powerful computers are well suited to rapid identification of particles of interest.

Rob's keynote was followed by three more important papers on ore sorting, including two from the leading manufacturers of electronic sorting equipment, TOMRA and Steinert Elektromagnetbau GmbH.

The emphasis on ore sorting at virtually all major mineral processing conferences is now very evident, so it was good to see that two of the five papers nominated for the 2015 Medal of the Coalition for Eco-Efficient Comminution (CEEC) dealt with pre-concentration of ores prior to comminution (MEI Online).

The CEEC Medal is an annual award for the most outstanding published paper, article or case study profiling beneficial strategies for eco-efficient comminution. One of the nominated papers was "Development of ore sorting and its impact on mineral processing economics" by Joe Lessard et al, published in Minerals Engineering (posting of 8th September 2014). Joe was also one of the presenters at Physical Separation '15, and we look forward to seeing his paper on the economic impact of ore sorting in the special issue of Minerals Engineering in a few months time.

But congratulations go to the winners of the 2015 Medal, Nigel J. Grigg and Georges J. Delemontex for their paper titled; “The Pre-Concentration of Precious and Base Metal Deposits Using the InLine Pressure Jig (IPJ); Higher Feed Grades and More Metal,” presented at the International Mineral Processing Conference 2014, Santiago, Chile.
Nigel Grigg (centre) of Gekko Systems at the 2014 AusIMM Mill Ops conference
This paper was selected for the 2015 CEEC medal because of the potential impact of pre-concentration in reducing the energy used in comminution, and the paper’s several quantified examples. The paper detailed the installation of IPJs in gold and polymetallic full-scale applications in the 1-15mm size range. It reported significant upgrade by the removal of low-grade ores, mainly silicates. The strategy of pre-concentration, either by the removal of gangue material before size reduction, or by separation of material for processing by alternate routes, significantly reduces the energy required for comminution, and decreases operating and capital costs. In addition, it effectively increases the size of the ore deposit.

CEEC and its Board, and MEI, congratulate Grigg and Delemontex on their win, and the other short-listed authors for their important contributions to the cause of reducing comminution energy consumption.

12 comments:

  1. The technology continues as work in progress. It will be great to see it scale to large high grade copper orebodies!
    Robert Seitz, Freeport-McMoRan Copper & Gold Inc, USA

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  2. Robert:

    I took a set of drill core data on 1-2 meter sections, a proposed mine plan, and an economic model of a sorting circuit plus it's effects on the rock flow and found that a 0.2% Cu deposit with a 0/15% cutoff, if sorted, could see 50% of the former mill feed rejected as waste. That is an impressive difference. Ken (KC) Armstrong, Allnorth Consultants

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    1. Thanks for that. I've seen similar results for ore types from a few orebodies.
      A major difficulty is dealing with the tonnages for porphyry copper deposits - 10s of thousands of tons per day up to 100K+. This is a scaling issue for sorting, material handling, etc. It would be great if Ken or others could comment around economically addressing these challenges.
      Robert Seitz, USA

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    2. Robert, you're absolutely right - bringing the technology to the masses is the important next step.

      The paper my company recently presented at Physical Separation '15 addressed this very issue. Titled "Bridging the gap: Understanding the economic impact of ore sorting on a mineral processing circuit," this work was a follow up study to the work short-listed by the CEEC. In this study we studied the cost, revenue and CAPEX associated with installing ore sorters at a Cu operation in the southwest USA. We had some very interesting findings that demonstrated the real economic feasibility of the technology. This work has been submitted for publication in Minerals Engineering.
      Joseph Lessard, USA

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  3. I feel that method of mining (open cast/underground) and ore formation will give a preliminary indication whether ore sorting would be feasible or not.
    Rao,T.C., India

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  4. Joseph - I'll look for your paper in upcoming Minerals Eng. Tadimety - Avoiding dilution in mining is a form of gross level sorting.
    Robert Seitz, USA

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  5. At IMPC 2006 in Capetown I had the opportunity to give a plenary speak with the title: "Sensor sorting technology – is the minerals industry missing a chance? ". That time many mineral processing colleagues did not even know that such technology exists. I remember that I had said that sensor based sorting should not be considered as last possibility if all other technologies fail but it should be considered in the early stage of a project- not only in the design of the mineral processing plant, but of the whole integrated mining and processing system. Now, nine years later the situation begins to change. SBS turns from a niche application to -hopefully- a key technology.
    Btw, "ore sorting" in my opinion this is not the correct term, as we also sort industrial minerals, gemstones, salt, coal, etc.
    Hermann Wotruba, RWTH Aachen, Germany

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    1. Hermann: I agree with you, it's been a long road to get the base and precious metal miners to be aware of SBS technology. It will be an even longer road to gain the investors trust that it is not a waste of funds to adopt SBS to build a smaller Mill, reduce the milling power costs, water consumption, size of the tailings and waste water facilities. What we need is a company like Phelps-Dodge which went with SX-EW technology for copper in the 1980's instead of bigger mines and mills, and survived. This time it could be SBS! What we also need is lower operating costs for base metal SBS. The value per ton of ore is generally too low to allow the cost of sorting plus separate discard of sorter reject. ORETOME Limited has been doing some testwork along these lines, google "Van Weert, humberetc" for (scanty) details. On the mine strategy side, the industry has to get rid of the tonnage bonus for Mine Superintendents, institute a bonus instead for (metal) value delivered to the MIll. The system should reward quality, not quantity!
      Gus Van Weert, UBC, Canada

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  6. I fully agree that rejection by any technique before treating the ore in a conventional beneficiation plant is a "must and highly profitable".
    Just for my information, I wanted to know where it is used for low grade (say <2% Cu in the r.o.m.) ore deposits
    Rao,T.C., India

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  7. It is very interesting to know.
    What method is used to ore sorting (TOMRA Sorting Solutions GmbH)? Photometric (Color), X-ray fluorescence method (XRF), method (XRT)?
    Natalia Petrovskaya
    nataliapetrovsky@gmail.com

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  8. I would be interested to know if the proposed technologies will go as far back as the pit itself for determination of economic processing ore grades - "hot spotting" the deposit. This will change the economic indicators of stripping ratios greatly and make some large deposits unworkable if the high grade is selectively mined. At that level the possibility of throwing out "parts of the baby with the bath water" becomes the issue. A target for presorting of the ore by grade should have a very low cut off ore grade - that alone would be more prudent?
    Mark Addison - Arizona.

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  9. The discussion continues on LinkedIn

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