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topic 59089

What equipment do I need to plate out Gold & Pt to test mineral samples

December 16, 2012

Q. I am setting up a small test lab to verify presence of the Pt group and gold elements in mineral samples by plating out a final product. I need to find where I can get a small 2 or 3 gallon tank (will a fish tank do)- and some carbon anodes- since my solutions may be caustic I am making SS pitchfork cathodes and have a variac transformer and voltage regulator set up.
Located in Canada and as I am a Geological and environmental Engineer have disposal under control
Thanks for help

Hugh Sutherland
Geological engineering and research - Orangeville, Ontario, Canada

December 22, 2012

A. Hi Hugh
I would put your chance of success at near zero.
Gold may plate out from relatively simple solutions;e.g. chloride or cyanide, but other platinum group metals will only plate from complex salts.
If you have the capability of producing these, you should find more conventional analysis simple.
If you do produce a deposit, how do you plan to identify it?
You should also know that a variac is a voltage regulator but only produces alternating current output which will not produce a plated deposit. You need a rectifier (and a chemist).

geoff smith
Geoff Smith
Hampshire, England

December 22, 2012

A. Good day Hugh.
Your letter has a focal point of verifying the presence of the Platinum Group of metals (Pt, Pd, Rh) and gold, by plating out a final product. This is very interesting.
As you are well aware, how can you presume the metallics which you intend to plate out from mineral samples are not contaminated with other minerals, e.g., iron pyrite etc.?
Regardless, I have reclaimed Au from gold solutions, as drag-outs from plating baths, and from CN based strippers.
The key for me was to use platinized titanium anode material;
this helps immensely, as any precious metal plater can advise. S.S. also works, however, not as efficiently.
pH values for acidic samples with Au @ ph 5.0-6.0 plate more efficiently, providing the solution has maximum conductivity as baumé - 10-20, and temperatures of 110-130 °F.
I used citric acid/potassium citrate to adjust ph/baumé, and current density values 10-15 amps./sq.ft.
The cathode material was S.S., as it is passive, allowing the Au deposit to be scraped off the cathode as gold (alloyed with whatever else was in the solutions... Ni, Co, In, etc.)
I used atomic absorption to verify that the solution did not contain any quantifiable concentration of Au.
Rh can be plated out similarly; the parameters for plating solutions are H2S04 @ 2.0-6.0% (aids in conductivity) , temp. 110-120 °F @ 10-20 ASF, using platinized titanium anodes.
A polypro or similar material would suffice as tank material, also S.S.
Question- why not digest mineral samples with aqua regia and use A.A. to verify presence of precious metals?
Technic can provide more details on precious metal recovery.
Hope this helps.
Best wishes for the Holidays!

Eric Bogner
- Toronto, Ontario, Canada

December 24, 2012

Thanks Eric
Q. Your response was along my line of thinking -- I have been working with a PhD Chemist who gave me the basics however I planned to use SS pitchfork cathode wrapped in steel wool and Dacron bagged, thus easing the gold precipitation. There are significant Pt, Rh, and Pd values present but at this point just looking to cupel a mixed bed to verify content. However I am still trying to find carbon anodes. Any ideas, as this whole concept is in the esoteric range (not normal extractions). I am looking for any help I can get, and it is hard and perhaps not wise to get into the full disclosure pattern as if I am right on this it could be huge. I know the gold is in my solution but am trying to get the best way to fine it

Hugh Sutherland
- Orangeville, Ontario, Canada

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