carbon containing gold,rhodium and many base metals

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arthur kierski
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carbon containing gold,rhodium and many base metals

Post by arthur kierski » November 9th, 2018, 5:59 pm

i have many kilos of this activated carbon deriving from the cleaning of industrial plating solutions-- i received 3,3kilos for testing the quantities of rh,au and any other pms --- well now , i wil describe the experiment that i did with 1kilo of this carbon---- I put 1kilo of this carbon in a oven with open door for some hours---after these hours the 1kilo became 55grams---- i reduced 1kilo to 55grams(94,5%)---this 55grams was treated with nitric(to see if any ag present)----no Ag----then the 55grams powder was treated with AR---the liquid was tested for gold,and the result was 1,14gram of gold---the powder left after the ar treatment,became 45,5grams---this powder where the rh might be,was magnetic---so now i have a powder(45,5) with suspected rh,fe , and ni--and perhaps other base metals------what does members of the forum would do with this powder ,to recuperate the rhodium?whem i saw that this powder had iron,i thought that more gold might have been precipitated into this 45,5grams of powder---i acept sugestions with pleasure---- thanks-------------------------------------------------------------------------------------------------------------------------------------------------------Arthur Kierski

nickvc
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Re: carbon containing gold,rhodium and many base metals

Post by nickvc » November 10th, 2018, 5:03 am

Arthur after a nitric soak and an AR one I doubt you will have any nickel or iron left, gold is one of the least reactive metals so if you have dissolved all the gold most of the other metallic elements should have dissolved with the exception of any Rh you may have, I’m not an expert at PGM refining and usually avoid messing with them if possible but I’m sure there are threads detailing it’s extraction and refining.

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g_axelsson
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Re: carbon containing gold,rhodium and many base metals

Post by g_axelsson » November 10th, 2018, 5:35 am

If the powder is black and magnetic it might be magnetite, Fe2O3. If there were any iron in the carbon it could easily been oxidized into magnetite when you incinerated the carbon.

Any metallic iron or nickel should have been dissolved in the aqua regia.

If there were any aluminium in the carbon it is probably oxidized into aluminium oxide and that is also resistant against aqua regia.

There is an old thread that might be of interest, http://goldrefiningforum.com/~goldrefi/ ... 51&t=14268 where Lou and Freechemist among others is discussing rhodium refining. Especially the last post by Lou is worth to note if you have problem with contamination in your rhodium sulfate solution.
Lou wrote:
June 19th, 2012, 8:22 am
The hydroxide treatment is really only applicable after most of the base metals have been removed. Iron, for instance, will contaminate it if one is not careful. Much of the garbage can be eliminated by proper treatment with sodium sulfide (removes other PGMs as well)...
I have no idea of how "proper treatment with sodium sulfide" is done though. :lol:

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g_axelsson
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Re: carbon containing gold,rhodium and many base metals

Post by g_axelsson » November 10th, 2018, 5:53 am

Doing some more research, magnetite and other iron oxides do dissolve in strong acids but it takes a long time to dissolve it.

For more in depth information on dissolving magnetite, see this scientific report.
DISSOLUTION OF IRON OXIDES AND OXYHYDROXIDES IN
HYDROCHLORIC AND PERCHLORIC ACIDS


Göran
Visit the GoldRefiningWiki, an online refining encyclopedia.
It also contains an online version of the book "Refining Precious Metal Wastes" by Hoke.

arthur kierski
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Re: carbon containing gold,rhodium and many base metals

Post by arthur kierski » November 10th, 2018, 8:51 am

Goran,the powder (45,5grams) is not black ,but it has a brownish collor---and is magnetic--not all the powder,but the powder dances when you pass a magnet---as i said ,i was told that there is rh in this powder----i even am thinking of using hf (100ml_) to eliminate eventual silica and dissolve other base metals----i also was surprised that there was iron and or niquel

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anachronism
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Re: carbon containing gold,rhodium and many base metals

Post by anachronism » November 10th, 2018, 5:29 pm

No need to use HF.

Out of interest, if it's activated carbon, cleaned and washed correctly prior to use, used to strip metals from a solution, why would there be silica there?
If you keep on doing what you've always done then you'll just keep on getting what you've always got.

"If you can bear to hear the truth you’ve spoken twisted by knaves to make a trap for fools, or watch the things you gave your life to broken, and stoop and build ‘em up with wornout tools" -- Rudyard Kipling

"The best diplomat that I know is a fully-loaded phaser bank." -- Lt. Cdr. Montgomery Scott

arthur kierski
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Re: carbon containing gold,rhodium and many base metals

Post by arthur kierski » November 10th, 2018, 5:45 pm

Anachronism---you are absolutelly correct----what would you do? i described exactly what i did,but members says that by my actions nor iron or niquel should be present in the45grams left---

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anachronism
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Re: carbon containing gold,rhodium and many base metals

Post by anachronism » November 11th, 2018, 1:31 am

I ash my carbon at no more than 650 degrees C Arthur. Temperature controlled. Then it either has a long HCL wash or goes straight to AR depending upon the base metal contents.
If you keep on doing what you've always done then you'll just keep on getting what you've always got.

"If you can bear to hear the truth you’ve spoken twisted by knaves to make a trap for fools, or watch the things you gave your life to broken, and stoop and build ‘em up with wornout tools" -- Rudyard Kipling

"The best diplomat that I know is a fully-loaded phaser bank." -- Lt. Cdr. Montgomery Scott

arthur kierski
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Re: carbon containing gold,rhodium and many base metals

Post by arthur kierski » November 11th, 2018, 5:57 am

Anachonism,i do exactly as you do---but i did the nitric wash to see if ag was present(no ag present but the nitric solution became blue -indicating copper)--then,i used ar on the powder left---after filtrating the ar to take out the powder that the ar did not dissolve,the filtrate was beautifull yellow solution ,from where with metabissulfite,i obtained 1,14grams of gold----Then i am left with 45,5grams of brownish material,with some probably Haematite,that Goran deduced that was formed by the of the carbon incineration,perhaps also some al2o3 that is difficult to dissolve in ar---Remembering that i am after the rhodium,in this 45,5 grams,and my past experiences ,and knowing that hf is used to dissolve metals oxides(specially iron oxides)---- i thought of using hf in this 45,5grams(only 150ml in a plastic bequer,would do the job--with all the precautions that is requred when dealing with this devastating acid)-----the second option that i found,is to fuse the 45,5 grams with Nahso4,obtain rh2(So4)3 and find the rh-------this test is for 1kilo of carbon-----then ,i will have to deal with at least 500kilos of this carbon---i know that the composition may be diferent---some will have ag,others pd,other gold and rhodium-----sorry for the long text---but with questionings and help from you,Goran,Nickvc, and others,i can elaborate a plan -----this forum gives me great experience ,knowledge and material satisfaction-------thanks all ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------Arthur Kierski

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