Rh and Pd extraction and separation

xelexo
Shop deals on ebay
Advertise with us
shop deals on amazon
Gold Refining Forum

Help Support Gold Refining Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
D

derik 234

Member
Joined
Apr 15, 2020
Messages
23
Hi dear, I read some of your topics on the forum about handling rhodium and palladium and respectfully I would like to know if you could instruct me. I have approximately 20 kg of scrap from galvanic processes plated with Rh and Pd in the final layer, and the lower ones are copper and tin and the piece is solid brass alloy 70% Cu and 30% Zn. I will send you photos of brass wires in this same alloy plated with these noble metals, Rh and Pd. My intention is to produce a Rh° and Pd° powder of acceptable purity.
I have reagents, equipment, ovens and structure.
I know it's a lot to ask, but would you be my mentor in this endeavor?
 

Attachments

  • IMG_20241022_110052.jpg
    IMG_20241022_110052.jpg
    223.5 KB
4metals said:
How much tin is involved? Is the wire a brass wire which is plated either with Rhodium or with Palladium and the wires are mixed?
Click to expand...
Considering only an ultra-thin flash layer of tin at around 2% representative of the total weight, copper will be in thicker plating layers and in the alloy. They are 70% Cu and 30% Zn brass wires, coated with Rh and Pd, mixed.
 
So to be clear the brass base material is a wire which is copper plated followed either by Rhodium plating or Palladium plating and then a flash top coat of tin? Presumably the tin aids in solder ability?

If the tin is in fact the top layer of plating but I want to be sure before proceeding
 
Copper and brass (zinc alloy) will be dissolved using sulfuric acid, copper and zinc can be precipitated by adding ammonium and calcium-based compounds for copper and zinc from the solution, ammonia-based solvents can be used to purify rhodium and palladium in the following steps.

Regards
 
4metals said:
So to be clear the brass base material is a wire which is copper plated followed either by Rhodium plating or Palladium plating and then a flash top coat of tin? Presumably the tin aids in solder ability?

If the tin is in fact the top layer of plating but I want to be sure before proceeding
Click to expand...
I value your dedication to the steps, they are brass wires in the 70% Cu and 30% Zn alloy that initially receive 2 thick layers of Copper, the first to level the surface and the second to give shine, the tin is the third layer and comes in as a small layer of flash, followed by the final layers of Pd and/or Rh and sometimes both are mixed.
 
SeRKaN PGM HuNTeR said:
Copper and brass (zinc alloy) will be dissolved using sulfuric acid, copper and zinc can be precipitated by adding ammonium and calcium-based compounds for copper and zinc from the solution, ammonia-based solvents can be used to purify rhodium and palladium in the following steps.

Regards
Click to expand...
Exactly it is an alloy, it proposes to dissolve everything in sulfuric attack, perhaps at a hot temperature of 60°C and continue precipitating aminocymplexes.
Going in aggressively with H2SO4 seems functional to me but not very efficient, the last layers are the ones of interest, the less they favor mixing between base, semi-noble and noble metals, the less difficult it will be to purify.
 
Last edited:
My concern about the tin is filtration if it is too high a concentration in your acid. If the last layer would have been tin it was a no brainer, but without other options I would with the thought that cold aqua regia will not attack the Rhodium and you should effectively dissolve everything else. The insoluble in this case would be the Rhodium. If you were to melt it all together and then react it it is possible you will have finely divided Rhodium which has a greater probability of dissolving in the aqua regia.

One could argue you could use nitric in which the Palladium is soluble and the Rhodium is not as well. In that case using Dimethylglyoxime to recover the Palladium would be my first suggestion unless there is a lot of Palladium in which case it becomes cost prohibitive.

It is entirely possible you may be able to melt the Rhodium foils or sell them as a powder (by grinding them) without further treatment (or expense)
 
How about trying a small batch with hot Copper Chloride aka AP and see if one can reach both the Tin, Copper and Zinc in one go.
Maybe they need to be squished/flattened a bit first.
Hot HCl with plenty bubbling may do the trick.
Or maybe not.

Take 100g or so and test.
 
4metals said:
My concern about the tin is filtration if it is too high a concentration in your acid. If the last layer would have been tin it was a no brainer, but without other options I would with the thought that cold aqua regia will not attack the Rhodium and you should effectively dissolve everything else. The insoluble in this case would be the Rhodium. If you were to melt it all together and then react it it is possible you will have finely divided Rhodium which has a greater probability of dissolving in the aqua regia.

One could argue you could use nitric in which the Palladium is soluble and the Rhodium is not as well. In that case using Dimethylglyoxime to recover the Palladium would be my first suggestion unless there is a lot of Palladium in which case it becomes cost prohibitive.

It is entirely possible you may be able to melt the Rhodium foils or sell them as a powder (by grinding them) without further treatment (or expense)
Click to expand...
These are important points, especially in the amount and concentration of acid to be used, a very common mistake that makes what is no longer easy very complicated quickly. Hydrometallurgical routes must be very considered, DMG in AR is a good option for Pd cost-benefit must be really analyzed, I do not intend to merge all the material initially I think about taking it easy.
 
Yggdrasil said:
How about trying a small batch with hot Copper Chloride aka AP and see if one can reach both the Tin, Copper and Zinc in one go.
Maybe they need to be squished/flattened a bit first.
Hot HCl with plenty bubbling may do the trick.
Or maybe not.

Take 100g or so and test.
Click to expand...
I will carry out this test and report it here, I will take a sample under moderate heating without O2 and we will see if a precipitate appears, it may work
 
derik 234 said:
I will carry out this test and report it here, I will take a sample under moderate heating without O2 and we will see if a precipitate appears, it may work
Click to expand...
The bubbling and thus O2 is what enables the formation of Copper Chloride which in turn is the active component.
HCl alone will only remove the Tin it has access to.
For this to be effective the wires may need to be cut in smaller pieces.

Lets see what the test say.

Nothing should precipitate by the way only dissolve.
So what should be left is the PMs
 
derik 234 said:
Exactly it is an alloy, it proposes to dissolve everything in sulfuric attack, perhaps at a hot temperature of 60°C and continue precipitating aminocymplexes.
Going in aggressively with H2SO4 seems functional to me but not very efficient, the last layers are the ones of interest, the less they favor mixing between base, semi-noble and noble metals, the less difficult it will be to purify.
Click to expand...
In concentrated hot (50-90 degrees) sulfuric acid, copper and brass do not dissolve, but are passivated.
This is how silver removal occurs.
but palladium can also be removed in this way.
Immerse the wires in sulfuric acid, heat them and add nitric acid little by little.
palladium will dissolve.
the base will remain untouched
then pour in this solution
into clean distilled water (dilute it) and put aluminum there.
add some hydrochloric acid.
All palladium will precipitate in the form of black particles
there will be about 800 samples of palladium.
 

Latest posts

Back
Top