Grinding & Classification Circuits

Grinding & Classification Circuits 2017-03-23T09:46:37+00:00
  • To participate in the 911Metallurgist Forums, be sure to JOINLOGIN
  • Use Add New Topic to ask a New Question/Discussion about Grinding.
  • OR Select a Topic that Interests you.
  • Use Add Reply = to Reply/Participate in a Topic/Discussion (most frequent).
    Using Add Reply allows you to Attach Images or PDF files and provide a more complete input.
  • Use Add Comment = to comment on someone else’s Reply in an already active Topic/Discussion.

Energy efficiency and the Mining industry (9 replies and 3 comments)

Bob Mathias
1 year ago
Bob Mathias 1 year ago

There is a strong push in the research community on optimistic energy efficiency through measuring minimum energy is required for comminution and benchmarking energy efficiency of different sites. On the other hand there are people who think optimizing mining and comminution with the aim of optimizing performance of the recovery process will be a better approach compared.
Do you think energy efficiency is a major challenge in mining industry or there are other aspects which should be addressed (i.e. process control, optimum operation condition etc.)?

Tony Verdeschi
1 year ago
Tony Verdeschi 1 year ago

Energy efficiency is important and needs study, but then so are process control, ergonomics, asset utilization, and many others. For any given operation there will be a hierarchy of priorities, but the next operation will have a different hierarchy.

Is energy efficiency a major challenge, yes. Is it the only challenge, no.

Energy is one of the most contribution in operating cost for mining and mineral industry. But it is not the only one. Using alternative sources if energy especially for remote mines can be solution down the track. Other solution can be synergy while one source of waste for an industry can be feed for another industry.
That is sustainable mineral processing that needs to be considered and studied more in detail.

Bob Mathias
1 year ago

I was wondering what is your definition of energy efficiency? Is there an agreement on definition among all operations?

Victor Bergman
1 year ago
Victor Bergman 1 year ago

Am not sure what you are trying to separate. Ore hardness is something that can be determined during drilling, though often this information is lost. Optimising energy efficiency would thus seem to start at the commencement of the project, and minimise having to remeasure data several times over.

Do you then separate the comminution energy as distinct from mine energy usage, as something different from combining the two to measure a site energy "factor". The idea of separately looking at mine energy, and mill energy as diferrent costs centres currently wastes over 13% of saveble energy. If the two are combined it may increase the mine energy by 10%, to get an optimum mill feed but this "increase" will save the mill 23%. Then there is the type of comminution employed in the mill. A competent engineer should be able to reduce the mill cost by 25% over someone who has a standard mill design that they apply to every client.

To me energy is a $/t of feed to the recovery section, independent of whether this "energy" is blasting, haulage, or electrical power to mills and agitators. For our clients getting the minimum risk, or cost is Paramount.

Bob Mathias
1 year ago

I actually think the mine to mill approach actually should extend to recovery and de-watering as well. Some energy optimization in mining and comminution might not be in favor of recovery and dewatering. That is where the definition of energy efficiency becomes important. Is it enough to say energy efficiency index is kWh per ton milled?

Tony Verdeschi
1 year ago
Tony Verdeschi 1 year ago

The mine that I am working, kWh per tonne is not that important as the throughput is low (40,000 t/y) but we produce 18 M lbs U3O8 eventually after ramp up. So definitely energy efficiency should be extended to other areas such as water treatment, tails dam, freeze plants in case of CL mine,

Victor Bergman
1 year ago
Victor Bergman 1 year ago

I am not sure there has been that much research on comminution energy reduction; although I would agree many researchers are claiming to work in the subject area.

So in the last 10 years what has been a researcher's specific contribution to energy reduction, and how has it been applied?

You make the comment re: mine to mill should extend to recovery. Of course.

When I was at JKMRC (I notce that you are from UQ and JKMRC is also part of UQ), we focused on simulating mineral processing plants holistically, but the reality is that most mineral processing engineers (particularly researchers) have great difficulty with a systems approach to mineral processing. So in the end, it was very difficult to create the holistic model through UQ/JKMRC, and instead simulation reverted to the conventional sub-circuit models (flotation/comminution etc.). This is why I am focusing on holistic modelling independently.

The main reason that a systems approach has been difficult for mineral processors has been use of a single datastructure. Clearly a multimineral particle datastructure allows holistic modelling, but understanding how to use this datastructure requires mathematical understanding beyond University-trained students and researchers.

Bob Mathias
1 year ago

I really liked your comment regarding challenges of integrated approach in the process modeling. Certainly, holistic optimization approach requires integrated process modeling capability. I am with you in using multi-component data structure. But I am very keen to understand how mathematical methods can replace with multi-component process modeling.

David Kano
1 year ago
David Kano 1 year ago

I have found it difficult to engage the operations folks in energy management. Many simplify the challenge as being something they can do very little about. I believe the reason for this that at least half of the energy consumed by a mine goes into the comminution and there are generally no short term solutions to fixing that problem. I have had a paper published in the Mining Engineering magazine over a year ago regarding this subject. If interested the following is the issue it was published in:

“Integrated sustainable energy management in mining operations” Mining Engineering, 2013, Vol. 65, No. 12, pp. 41-41 Bush, Victor

Helena Russell
1 year ago
Helena Russell 1 year ago

From a mill designer and operator point of view it is difficult to defend not treating as much feed through your grinding circuit as the down stream metal or mineral recovery systems can efficiently recover. often it makes sense to mill more material at a somewhat less than optimal particle size and achieve less recovery but produce more metal or mineral. Give up some recovery for a larger % increase in throughput is another way to put it. Often the grinding costs are a small portion of the revenue extracted per ton of ore so being more energy efficient results in less revenue in many mill circumstances.

Most grinding circuits are designed larger than needed for much of the ore feed. This leads to energy inefficiency in the circuit. However, if one is not designed in this way when the hard ore hits then profits suffer from the lower throughput and revenue. Better to lose some money due to less than optimal mill power consumption per ton of ore during the softer ore campaigns than lose the production revenue when the hard ore arrives. It is a fine line to maintain. As a mill designer you try to keep as much flexibility in the design to allow the energy to ramp up and down without losing too much power efficiency when running on the softer ores, but keep the throughput as close to design when the harder ores are processed. Obviously one would like to cram as much ore through as possible when ore is softer but there are other downstream system constraints that limit the upside throughput to 15-25% of the design rate normally.

David Kano
1 year ago
David Kano 1 year ago

You make a very valid argument, particularly with regard to grinding costs being a small portion of the revenue... To that point, many of the folks responsible for production targets, energy consumption becomes irrelevant due to the frame of reference.

For example, lighting in underground and surface operations, in many cases, does not register in the utility bill. Using that frame of reference makes it easy to ignore. On the other hand if one changes the frame of reference and equates the lighting savings, for example, to the office administration's salary, it becomes more relevant. Changing the frame of reference is critical for engagement of operations.

Bill Fraser
1 year ago
Bill Fraser 1 year ago

Energy efficiency of a mining project start at planing and design stage to suggest cost effective mining , processing to maximum metal recovery, and providing facilities for optimum use of energy. Although there are simulation technology available for optimization of process/schemes in mining project, but the operating personnel need to be aware of the optimization energy process so that kwh/tonne of concentrate is minimum . Its also essential to plan the energy mix with a supply of renewable energy specially in remote ares of mining venture.

Paul Morrow
1 year ago
Paul Morrow 1 year ago

In conventional base metal milling throughput always trumps recovery for maximizing revenue. This has been demonstrated over and over again.

TPD also trumps energy efficiency, especially when the plant design did not permit design t/h to be reached until additional capital has been spent (often for pre-crushing). In this case energy efficiency is accidental, not planned. The sequence to achieve energy efficiency is first to get the grinding circuit design right, operate the plant to be profitable as planned, and then work on the optimization of energy usage to improve the economics, using the equipment available. The exercise must start with proper design to give required TPD.

Please join and login to participate and leave a comment.