# Furnace Temp / Cupellation process for Getting Metallic Oxide Sponge contain PGMs.



## CO-WYO-Peter (Feb 16, 2022)

Refiners,

I am working with placer concentrate and leaching. On XRF - the concentrates show Au, Pd and Rh at decent % (I understand that xrf is just a guide in this situation).

I am experimenting with AP and SSN leach methods on my concentrate to see if I can capture some of the pgms and Au. I am able to produce a metal sponge via cementation with zinc. I take the sponge and wash with dilute nitric to remove other metals. I then take the dried sponge, wrap it in lead foil and place in my furnace and cupel it away (read this via Walter Leashy). In this process I only end up with beads of gold and seemingly not the pgms. There is a slag surrounding the cupel. I understand there maybe better process - but I am trying to work with what I have and is easy to do.

My question is about the lead foil /cupel process.

* Will pgm oxides convert and go into lead with a furnance that only goes to 2000F? I do not have a furnace that goes higher?*

Many thanks,
Peter


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## Yggdrasil (Feb 16, 2022)

Without knowing for sure, I suspect XRF confusion.
XRF are good for the libraries they have. If they don't have the correct library they guess.
Arsenic is mistaken for Iridium and such mistakes.


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## CO-WYO-Peter (Feb 16, 2022)

Yggdrasil,​I understand your point here. However, the host mineralogy is compatible with pgms (source of material mafic basalts). Where did you come up with Ir? Because I have reports of sophisticated report suggesting that it is the predominant native metal in the concentrate is Iridium (academic research 1984). In the xrf above I read Indium not Ir - However, seems that the Fe, Cd, Sn should suggest association with PGMs.

I am trying to figure out in my process can I convert any potential pgm oxides via cementation to alloy with molten lead at 1750-2000 F in my furnace - or do i need high heat? Or at such a low temp there is no metallic conversion.


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## CO-WYO-Peter (Feb 16, 2022)

CO-WYO-Peter said:


> Yggdrasil,​I understand your point here. However, the host mineralogy is compatible with pgms (source of material mafic basalts). Where did you come up with Ir? Because I have reports of sophisticated report suggesting that it is the predominant native metal in the concentrate is Iridium (academic research 1984). In the xrf above I read Indium not Ir - However, seems that the Fe, Cd, Sn should suggest association with PGMs.
> 
> I am trying to figure out in my process can I convert any potential pgm oxides via cementation to alloy with molten lead at 1750-2000 F in my furnace - or do i need high heat? Or at such a low temp there is no metallic conversion.


Also the owner of the XRF said that the libraries are correct and the tool had been recently calibrated.


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## Yggdrasil (Feb 16, 2022)

Just wanted to make you aware of the special situation.
Regarding oxidation of PGMs.
No they oxidize even less than gold.
Actually one of the industrial concentration methods is oxygen sparging through the melt to oxidize away anything else than precious metals.
If there are PGMs in your feedstock, it could be to little to change the color of the button.
Have you tested your button with XRF?


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## Yggdrasil (Feb 16, 2022)

CO-WYO-Peter said:


> Also the owner of the XRF said that the libraries are correct and the tool had been recently calibrated.





CO-WYO-Peter said:


> Refiners,
> 
> I am working with placer concentrate and leaching. On XRF - the concentrates show Au, Pd and Rh at decent % (I understand that xrf is just a guide in this situation).
> 
> ...


An addition here.
PGMs create quite nasty salts that can lead to deadly deseases.
Be careful.
And the process you have outlined are not very good for PGMs.
Zinc will take them all out of solution.
Do not use Nitric, it will dissolve Silver and Palladium. Even some Platinum will follow if intermingled with Pd and Ag.

Just take the heavies, mix them with litharge and wrap them in lead.
Straight to the cupel.
Test the button after.
At least this is how I would do it.


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## CO-WYO-Peter (Feb 16, 2022)

Yggdrasil,​
thank you very much.

What method would your recommend for pgm evaluation?


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## CO-WYO-Peter (Feb 16, 2022)

Also Pgms will not effect the color of the bead like Ag does?


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## Platdigger (Feb 16, 2022)

If you really think you have much pgms, pay for a proper assay that uses nickel sulfide.
For a good rhodium assay expect to pay more yet.


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## CO-WYO-Peter (Feb 16, 2022)

Thanks Platdigger. 

I have for Pt, Rh and Pd with Hazen Research. The assays show low amounts (almost trace levels) pgms compared to Au (which I know i have). I believe the pgms are in spinel form and may be difficult to analyze. 

However, in my leach process I am showing at least 2x the amount Au than in FA evaluation. On my project I am primarily concerned with Au - however the area is know to contain pgms especially Ir. 

This is winter garage project. I like the ability to perform the leach and actually weigh out the precious metal alloy. I know the beads are comprised of a precious metal because I perform post digestion in cold/hot/weak and strong nitric acid - and bead will not be attacked. 

I need to figure what the composition of the bead - but I am trying to collect several grams of metal before sending out to the lab. 

I am working on 250 gram leach trials. I have been focused currently on HCL +H2O2. You can see my simple leach process in the photos attached.


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## Lou (Feb 17, 2022)

Send it to ACT labs for INAA.


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## CO-WYO-Peter (Feb 17, 2022)

Lou, 
I love ACT labs - especially for REE. What is IN method?


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## CO-WYO-Peter (Feb 17, 2022)

CO-WYO-Peter said:


> Lou,
> I love ACT labs - especially for REE. What is IN method?











Precious Metal Analysis - Actlabs


PRECIOUS METAL ANALYSIS Accurate and precise precious metal analysis can be performed by using fire assay, cyanide leach, aqua regia or INAA. Precious metal analysis is usually determined by using either a lead or nickel sulphide fire assay pre-concentration step prior to analysis. This is...




actlabs.com


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## CO-WYO-Peter (Feb 17, 2022)

Refiners - I want to make sure that this point is correct:

If I produce a metallic sponge from my leach process via cementation. That I can take that sponge suspected to have pgms, wrap it in lead foil and cupel it. The temperature of the furnace running at 1750 - will infact convert the pgm metal oxides to metallic form at this temperature and allow them to alloy with lead?


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## Lou (Feb 17, 2022)

Ru/Os/Ir don't really alloy with lead but PdPt and to much lesser extent Rh do. So Pb not good for Ir.


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## CO-WYO-Peter (Feb 17, 2022)

Thanks Lou,

I read in Ammen on Platinum - that lead was a very good collector. I will try a smelt method next = sponge + borax + induction furnance to a conical mold.


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## Platdigger (Feb 17, 2022)

So Lou, what do you think of ALS labs in Reno?
I see they have some real good prices.


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## Lou (Feb 19, 2022)

Never used them. We usually send to ACT, Ledoux, and sometimes MCCreath.


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## PeterM (Apr 9, 2022)

CO-WYO-Peter said:


> Refiners - I want to make sure that this point is correct:
> 
> If I produce a metallic sponge from my leach process via cementation. That I can take that sponge suspected to have pgms, wrap it in lead foil and cupel it. The temperature of the furnace running at 1750 - will infact convert the pgm metal oxides to metallic form at this temperature and allow them to alloy with lead?


CO-WYO-Peter, why do you want to cupel it? Once you have made the metallic sponge, it is metal and can be sold to any major refiner as is, don't complicate it. They are going to dissolve it and re-refine it, why make a problem toward your sale?


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## CO-WYO-Peter (Apr 9, 2022)

PeterM,
I am working on small scale tests and want to see with my own eyes. This procedure was outlined in the SSN Document writer by Walter Lashley.

Also, this is the capability that I have in my garage over the winter testing period ( furnance, labware and some acids). - until I head back to my mining project.

Through cupelling I can see the effects of different leaches and strengths on gold recovery for certain.

In my process I have switch from the AP to the SSN works alot better on my ore and cement carefully with Cu.


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## CO-WYO-Peter (Apr 9, 2022)

However, I have learned that cupelling is not the right way to go to create pgm metals. It is my understanding that what is left on the sides of the cupel wall can be pgm sponge.


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## orvi (Apr 9, 2022)

CO-WYO-Peter said:


> However, I have learned that cupelling is not the right way to go to create pgm metals. It is my understanding that what is left on the sides of the cupel wall can be pgm sponge.


Only one method of "cupelling" PGMs I encountered and it work relatively OK is alloying with plenty of silver and then performing cupellation. Just lead and PGMs create Pb/PGM alloy, which composition depends on the temperature of cupelling - as PGM´s have insanely high melting points compared to AuAg.
Diluting the melt with silver can lower the temperature required for cupelling out the lead. Then you dissolve the button in nitric acid, recover silver with HCl as silver chloride, and you are left with mainly Pd/trace Pt solution and insoluble PGM residue. You can directly cement PGMs from the solution with copper, and you recover relatively pure PGM precipitate.

For good pyrometallurgy on PGMs, you need to get to very high temperatures. On amateur scale, it is relatively hard to do in bigger volumes. Most of the catalysts are difficult to liquify matrixes, composing of zirconia and alumina etc. Special ceramics in MLCCs do not simplify it either. It sounds insane, but our best recoveries on MLCCs (old) were performed, when silica was used as flux - making eutectic with titanium ceramics. Induction furnance, magnesia layered graphite, 1600+°C. Compared to Na2CO3/cryolite flux, yield was 20% better. 

PGM recovery is hard. Not speaking about refining them. Not science, but much more of an art


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## CO-WYO-Peter (Apr 9, 2022)

Thanks Orvi, 

A lot to learn for certain when it comes to the pgms. I have all the evidence that they are there in my concentrate. I just want to realize the metal with my own procedures.


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## JonnaGr (Sep 20, 2022)

PeterM said:


> CO-WYO-Peter, why do you want to cupel it? Once you have made the metallic sponge, it is metal and can be sold to any major refiner as is, don't complicate it. They are going to dissolve it and re-refine it, why make a problem toward your sale?


Hello!
Which refineries do you recommend for sale? On low scales, for example 10-20kg with 10% pgms


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