# How to recover Au,Pt,Pd,Rh from unknown metal



## alb320 (Mar 25, 2009)

Hi guys...
I have posted this question already. 
But I would know you know an easy way for make this process.
I have these ingots that contains Au,Pt,Pd,Rh... Iron and others unknowns metals. 
I would have a ingot of Au,Pt,Pd (and if possible Rh) but without iron...
I'm not interested for pure metal.. but for an Ingot that contain all preciuos metal.
I have 4 professional furnaces and one glass AR reactor... 

How I could do this process with this equipment?

Thank you!!


----------



## Lou (Mar 25, 2009)

I'm sorry, but your question was unclear.

I assume you want to separate them?


First, you would be best served by changing the physical form of the ingots and making small shot-like pieces (as in tiny spheres). 

After that, we will discuss what to do.


----------



## alb320 (Mar 25, 2009)

Yes Lou.. I would separate precious metals to Iron.
Ok, no problem, I can tranform it in small speres...
I have a lot of this metal in small speres already.
And after this step? 

Thank you Lou..


----------



## Harold_V (Mar 26, 2009)

One of my observations in processing materials that are sulfides is that you can eliminate the sulfur by adding scrap iron, which reacts with the existing sulfides, liberating the more noble metals and forming a compound with iron. I wonder----could a person add sulfur to the mix, forming iron sulfide? If so, it would go off in the slag, but stratify between the slag and the target metal. I would imagine that the iron could be eliminated that way. Opinions?

Harold


----------



## qst42know (Mar 26, 2009)

Fulton describes the use of iron nails and soda ash to remove sulfides from ores during assaying. 

Perhaps you could use sulfides when melting to remove the iron.

Search (iron nail) to bring up the pages.

http://books.google.com/books?id=xc8wAAAAMAAJ&pg=PA134&lpg=PA134&dq=assaying+precious+metals+fulton&source=bl&ots=PzvqTa-Y8n&sig=YUqpeIFcfqGuNzHXxZoPUubf9KE&hl=en&ei=8DnLSaLdFuDonQetxaXOCQ&sa=X&oi=book_result&resnum=1&ct=result#PPA149,M1


----------



## alb320 (Mar 26, 2009)

I can't see the page of the book in your link... It is protect by copyright.


----------



## Lou (Mar 26, 2009)

Sulfur is generally a very bad thing to admix with the PGMs--all are attacked by sulfur to varying extents.

If you can be guaranteed that you can effectively separate the FeS from the PtS, Rh2S3, and other mixed sulfides physically, it is probably a good way to go. 

I'd have to look at solubility and and how acid stable they are in relation to each other. You may be able to toss everything in with sulfur as the oxidizing agent and then selectively dissolve the precious metals at various pH. 

If it were me, I would try casting shot and trying to dissolve as much as possible of the material in hot 5M HCl. A small amount of palladium/gold may go into solution, but this is probably negligible. This treatment ought to remove much of the iron and other metals like chromium and nickel. 

If cobalt and copper are serious concerns, after the boil with HCl and a good washing with distilled water, nitric should be employed. Pink solution is cobalt, green-blue is copper with nickel perhaps mixed in as well.This will dissolve the palladium, and trace HCl present will dissolve traces of gold and platinum, which may also give a yellowish-orange color. If there is significant palladium, the solution will be brown. This should be boiled down with hydrochloric acid to expel all the nitrogen oxides, and then heated to blood temperature and a saturated solution of ammonium chloride added. Sodium chlorate or bleach may be added (with careful pH control) to precipitate out a dirty red ammonium hexachloropalladate. This can then be redissolved in ammonia, filtered, and reprecipitated with HCl, washed with cold saturated ammonium chloride, and then repeated if so desired.

The residuals will be the gold, platinum and rhodium. A room temperature soak with aqua regia will separate the gold from the platinum and rhodium with only minor platinum contamination. If that is undesirable, a warm sodium or potassium cyanide solution can also dissolve the gold (Be very careful with cyanide: remember to ensure that it is pH 11 and to add small amounts hydrogen peroxide). I would then process the gold containing aqua regia solution as per the normal routine (boiling to remove nitrogen oxides, addition of HCl, concentration, and precipitation with sodium sulfite/oxalic acid/SO2 gas). 

The platinum can be separated from the rhodium in several ways. One such way is to take advantage of rhodium's relative insolubility in aqua regia. A hot 90*C solution of aqua regia will dissolve platinum powder rather quickly. This is then treated in the usual manner and precipitated with ammonium chloride to yield the hexachloroplatinate complex, which is then either thermally reduced, or done chemically with hydrazine (or one of its salts), hydroxylamine, acidified ammonium formate, borohydride, or at high temperature with hydrogen gas. A black to gray powder remaining undissolved will be rhodium, ruthenium, or iridium. If you strongly suspect your material to only contain rhodium, it is probably quite pure as it is since everything else has been dissolved away. If you want to know how to refine rhodium, I can tell you that as well.


This is by no means the best method to do it, but it's one that should work fairly well, and the best that I can come up with on 4 hours of sleep in the past 48 hours.


Lou


----------



## Irons (Mar 26, 2009)

Harold_V said:


> One of my observations in processing materials that are sulfides is that you can eliminate the sulfur by adding scrap iron, which reacts with the existing sulfides, liberating the more noble metals and forming a compound with iron. I wonder----could a person add sulfur to the mix, forming iron sulfide? If so, it would go off in the slag, but stratify between the slag and the target metal. I would imagine that the iron could be eliminated that way. Opinions?
> 
> Harold



The Iron-Sulfur reaction is exothermic. It's not as bad as Zinc-Sulfur, but.......

Using dilute Nitric afterwords will break down the sulfide into free sulfur and the Iron will go into solution.

Using dilute sulfuric acid and H2O2 will give more sulfuric and ferrous sulfate. Be sure it's dilute and use very little H2O2. The PGMs will break down the H2O2 into water and O2, violently if concentrated.

An example of H2O2 and PGM catalyst:

http://www.the-rocketman.com/space-age-racing.html


----------



## alb320 (Mar 26, 2009)

Thank you Lou and Irons.

I will try to do all processes and I will see wich are the easy/profitable way...

Thank you a lot!!

Next week I will try it and I will post my result!


----------



## Irons (Mar 26, 2009)

alb320 said:


> Thank you Lou and Irons.
> 
> I will try to do all processes and I will see wich are the easy/profitable way...
> 
> ...



Use small samples until you get a feel for what works the best.

Good luck.


----------



## alb320 (Apr 15, 2009)

guys... I have tried to dissolve my "iron" in HCl...
I have put 1,45 kg on 10 liters of HCl 33%, and after 5 hours I have got a black solution with a black mud on the bottom of the tank, and some solid pieces..
What I have to do now? 
I have to filter all of solution? if yes, what I could use such as filter? 
Is gold in black mud? or in solution also?


----------



## oef62nd (Apr 18, 2009)

Try this

See Attn:


----------



## alb320 (Apr 29, 2009)

Hi guys,
I have dissolved all iron!! I have used Hcl 30% and H2O2 30%, Solution scale 3:1. 
Dissolved, Filtered and melted... and now, I have a ingot that containts Au, Ag, Pd, Pt and a little of Rh....

I hope that may experience can be useful for someone...


----------



## Oz (Apr 29, 2009)

I hope you checked your wash water for values, HCl/H2O2 will put values into solution. Do not throw the baby out with the wash water.


----------

