Laboratory Testing & General Mineral Processing Engineering

Laboratory Testing & General Mineral Processing Engineering 2017-04-04T06:57:51+00:00
  • To participate in the 911Metallurgist Forums, be sure to JOINLOGIN
  • Use Add New Topic to ask a New Question/Discussion about Mineral Processing or Laboratory Work.
  • 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.

Concentrate Marketing and Rejection Limits (5 replies)

Tony Verdeschi
2 years ago
Tony Verdeschi 2 years ago

hello everyone!! Can anyone please help me with some Concentrate Marketing and Rejection Limit issues.  I need to know more about threshold value of Copper ore or any other, less than which can be reject? and whether this value may vary from deposit to deposit or particular belt? Actually sometimes we have to beneficiat very low grade sample, of course this has to do in perception of zero mine waste, but then why this threshold value is marked?

Bill Fraser
2 years ago
Bill Fraser 2 years ago

Simply depends on the price of copper in the market place.

And the costs of extraction.

Threshold value is function of so many factors; staring from the location/country of the deposit; mineralogy , process selected for maximum recovery at a grade aimed, tailing disposal etc.etc in addition to forward integration. So a general question like that would be difficult to answer.

David Kano
2 years ago
David Kano 2 years ago

Yes, it all depends on the market as alluded by Mr Rao and Rawle. You can estimate it from the following Cutoff grade formula:

  • CoG = m/(p-s) x r where
  • m is the milling cost ($/t)
  • p is the sale price of the commodity ($/t) 
  • For different commodity prices refer to Metal-Prices-in-the-United-States.pdf
  • s is the sales cost (i.e. refining and marketing) ($/t)
  • r is the process recovery (%)

Here is an example:

Estimate the unit profit of mining and cut-off grade of a copper ore body with 0.82% of copper, if the selling price of copper in the concentrate is $1.63/kg. Assuming that the overall cost of mining and processing is $7.50/tonne and grade of Cu in tailings is 0.07%.


Recovery = (Feed – tails grade)/feed grade = (0.82-0.07)/0.82 = 92%

Gross Value = Grade x Recovery x Price x Conversion Factor


Gross Value = 0.0082 x 0.92 x 1.63/kg x 1000 kg/tonne

= $12.29/tonne

CoG = Cost/[Price x Recovery]

  • = ($7.50/tonne)/ ($1.63/kg) x (0.92)
  • = 4.2 kg/tonne or 0.42% Cu by weight


  • Profit = Gross value – cost
  • = 12.29 – 7.50= 4.8$/tonne
Bill Fraser
2 years ago
Bill Fraser 2 years ago

Good example and may give an indication based on the mathematical equation; still too many assumptions on cost of processing/recovery etc.

Bob Mathias
2 years ago
Bob Mathias 2 years ago

All of those above have opinions expressed are correct and beneficial to such a general question. The price of copper in the market place is very critical and the mineralogy . Industry have gone through different and diversified transformation and the right understanding is needed to estimate cost of production which involves different and diversified functions . Go to onemine and type your question more specifically and a lot of information would be available.

Bill Fraser
2 years ago
Bill Fraser 2 years ago

I agree! Mineral exploitation is more complex, not in understanding what to do and how to do, but the parameters required are quite a few and there are no thumb rules. The economics may keep on changing depending on not only the market price of the metal but also the variations in ore characteristics, more stringent environmental issues etc.

We need more understanding and expertise. 

Please join and login to participate and leave a comment.

BUY Laboratory & Small Plant Process Equipment

We have all the laboratory and plant equipment you need to test or build/operate your plant.

ENTER our Mining Equipment' Store

We Sell EQUIPMENT for all types of Mineral Treatment PROCESSES and Laboratory Testing needs

Have a Mineral Processing QUESTION?

Come in, ask your question

911Metallurgist Community Forums

Talk to other metallurgists and be helped.


We can IMPROVE ALL PLANTS / Mineral Processing Engineering & LABORATORY Ore Testing

911Metallurgy Engineering

Contact us for process engineering, metallurgical investigations, plant optimization, plant troubleshooting, needs. WE “FIX” METALLURGY.