A XRF Analysis of my ore.... Your thoughts... please!

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PCZim

Member
Joined
Jan 1, 2015
Messages
19
Dear members

I have done a XRF analysis on my ore at my gold mine. The gold samples I know already however I thought I would learn a bit more about the composition of my ore. Here are the results.... Please someone tell me some of the other elements are commercially viable (Yes I have researched every element mentioned already) and how could they potentially be extracted as a by-product of gold. Your advice and input is very welcome here as I am scratching my head. I have been a gold miner for 10 years now but I have no experience in other minerals. If I can I would leap at the chance to value add onto my mining operation.assay1screenshot.png
 
I doubt you will get much input from the members but if you can tell us how you process your ore perhaps some of our clever chemists might be able find something which would make it profitable to process some of the other elements.
 
Thank you Nick for the reply.

We mine underground so after extraction, I mill the ore through ball mills followed by centrifugal concentrators. The sand and slimes gets piled, sun dried and put into vat leach tanks where we treat with cyanide.
 
Unless any of the other elements are dissolved by the cyanide I think you are probably not going to be able to do any more, once the cyanide has been used it’s highly dangerous to then proceed to use acids or the other way round for fairly obvious reasons , perhaps some one else may have other ideas but I’m at a loss to advise any further I’m afraid.
 
You have nothing of value in the metals listed, the cost of extraction would be much greater than the metal value.
The grades shown would not be viable for upgrading by flotation.
A good rule of thumb is that you need to have at least 0.1% metal values in a previously milled ore to be of any interest for flotation, this is dependant on which metal you are looking at.
There are literally billions of tons of base metal tailings which have higher metal values than your ore, these tailings are not being worked because there is no money in doing so.
What you did not show on your list was precious metal values, silver and the PGMs are your only chance of having some element which can be profitably recovered and that depends on not only the grade but on the mineral form it is present in and how it is distributed in the ore.
Deano
 
Deano said:
You have nothing of value in the metals listed, the cost of extraction would be much greater than the metal value.
The grades shown would not be viable for upgrading by flotation.
A good rule of thumb is that you need to have at least 0.1% metal values in a previously milled ore to be of any interest for flotation, this is dependant on which metal you are looking at.
There are literally billions of tons of base metal tailings which have higher metal values than your ore, these tailings are not being worked because there is no money in doing so.
What you did not show on your list was precious metal values, silver and the PGMs are your only chance of having some element which can be profitably recovered and that depends on not only the grade but on the mineral form it is present in and how it is distributed in the ore.
Deano
Click to expand...
The abscence of gold caught my attention as well.
As he said he is (succesfully?) mining gold and wants to know what else is in his ore, i think this XRF 'assay' is done on the cyanide leached tailings.

With any XRF report i would expect the type, seriall number and calibration date of the instrument used in the report.
Then following Deano's reply, the conclusion will be: not worth it to process further.
 
Martijn said:
The abscence of gold caught my attention as well.
As he said he is (succesfully?) mining gold and wants to know what else is in his ore, i think this XRF 'assay' is done on the cyanide leached tailings.

With any XRF report i would expect the type, seriall number and calibration date of the instrument used in the report.
Then following Deano's reply, the conclusion will be: not worth it to process further.
Click to expand...
Thank you. These are the replies I was looking for. The gold content of this ore was done by fire assay and is reading at 15.2 g/t of which I extract around 5g per ton in free gold and around 4g/ ton in the sands.

The assay was done before leaching, I just excluded gold as the cost of the XRF would have risen by another $60 (that's me being tight fisted!) My test was just for an initial idea.
 
Deano said:
You have nothing of value in the metals listed, the cost of extraction would be much greater than the metal value.
The grades shown would not be viable for upgrading by flotation.
A good rule of thumb is that you need to have at least 0.1% metal values in a previously milled ore to be of any interest for flotation, this is dependant on which metal you are looking at.
There are literally billions of tons of base metal tailings which have higher metal values than your ore, these tailings are not being worked because there is no money in doing so.
What you did not show on your list was precious metal values, silver and the PGMs are your only chance of having some element which can be profitably recovered and that depends on not only the grade but on the mineral form it is present in and how it is distributed in the ore.
Deano
Click to expand...
Hi Deano

Thank you for the reply and the honest feedback. I will further test for PGM's, the lab told me that their XRF cannot test for PGM so I am collecting a sample tomorrow for fire assay.

Gold I always do fire assay, in this ore fire assay reads at 15.2, free gold extracted is around 5g/ton and around 4g/ton in the sands. I guess the extraction is less as the ore has a large amounts of pyrites in in.

There is minimal silver, I know this because when I elute, the acid residues I precipitate with course salt and very minimal silver comes out.

Im glad for the feedback and the rule of thumb you mentioned to me. Thats just saved me a lot of time and effort in barking up the wrong tree.
 
PCZim said:
Thank you. These are the replies I was looking for. The gold content of this ore was done by fire assay and is reading at 15.2 g/t of which I extract around 5g per ton in free gold and around 4g/ ton in the sands.

The assay was done before leaching, I just excluded gold as the cost of the XRF would have risen by another $60 (that's me being tight fisted!) My test was just for an initial idea.
Click to expand...
Sounds like he's only in it for the money, not for actual quality reports on mineral content.
I would advise to find an "assayer that tests for minerals in the ore, not one which you have to pay per element. That is nonsense imo.
xrf is a surface scan, not an assay. it goes only so deep and it can indicate which metals are in there, but it remains somewhat of a guess on the percentages and it also depends heavily on the method of sampling and testing. is it an average of many measurements or just one scan on one spot of dust how thick i the dust layer, etc. etc.
 
Martijn said:
Sounds like he's only in it for the money, not for actual quality reports on mineral content.
I would advise to find an "assayer that tests for minerals in the ore, not one which you have to pay per element. That is nonsense imo.
xrf is a surface scan, not an assay. it goes only so deep and it can indicate which metals are in there, but it remains somewhat of a guess on the percentages and it also depends heavily on the method of sampling and testing. is it an average of many measurements or just one scan on one spot of dust how thick i the dust layer, etc. etc.
Click to expand...
Thank you. I was super interested to learn what else is in my ore, I was particularly looking for elements that can potentially play games with my cyanide, apart from a bit of Zinc, I think Im ok.

I know assays can also be so inaccurate, even on a fire assay, for example I recently did a fire assay on some schist that I have a few thousand tons of, it read at 0.18g per ton however when I milled it the gold came as .5g per ton and the sand on a bottle roll assay reads at .95g per ton. I actually hate assays and rarely do them, I normally like to get true results from extraction. Assays play with my head too much and I ask myself too many questions.

Sometimes I am content to be of the mindset "what I get is what I get" and other times I want to know what I am missing out on and how can I improve.
 
I think Deano would agree with this comment , an assay if done properly will tell you how much gold you have in your ore but getting all of it can be totally impossible or not financially viable but it can be used to try to improve your recovery rates , chasing after small amounts can be a lot less profitable than processing more ore.
 
I will add my 2 cents to the conversation, and it is worth exactly what you paid for it.....

If you are using a cyanide lead on your concentrates, I would suspect you are probably extracting most of the copper and silver in the preg solution. Your easiest increase is to optimize your system. You are currently sitting at 60% recovery after crushing(assumed) grinding and concentration. Increasing recovery by even 5% will pay larger dividends to you.

One of the major issues in mineral estimates is sampling. Getting a representative sample of the minerals in a deposit is challenging. At this stage of your operation, if only had the budget for five assays, I would suggest two from your final mill discharge, one from your centrifuge con, one from your centrifuge underflow and one from your post-leach tails (I am assuming a vat or batch leach instead of a heap leach). These would have the advantage of being relatively homogenous and would allow you to back calculate your head grade to compare against your mill discharge.

As has been stated, the handheld xrf is not up to the task you asked it to complete. You would be better off sending off the samples to lab that can do an ICP analysis. The international labs can give you industry-standard accuracy of 32 or more elements for about $150 per sample.

Having said that, the information you provided indicated greater-than-background concentrations of Gallium and Rubidium. If valid, these may be able to increase the value you receive but it would take some work. Good luck and remember the most important thing to come out of an underground mine is the miner.
 

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