# rhodium plated over copper wire



## arthur kierski (Mar 27, 2010)

i received 70kilos of rhodium plated wire and up to now i used to obtain the rh foils with nitric acid leaching--(i receive this material every 6months)----the yeald was 0,7grams of rh per kilo
although nitric acid here is relatively cheap compared with other countries(110 dolares per 50litres),i was thinking of using ar(much cheaper then nitric) to do the leach)------question: does in this conditions ar dissolve rh or leaves rh foils after the leach?
i ask this question because when i did this work with plated rh over fantasy jewellery (with ar) last year the rh yeald seemed lower then with nitric leaching----
note:the nitric leach of the 70kilos would cost me 550dollars---the ar leach would cost me 224 dollars
thanks for replies
Arthur


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## samuel-a (Mar 27, 2010)

hi arthur.
would you please upload a picture of your Rh/Cu wires?
so that one can identify this kind of matirial in the future while scraping items..
thank you.

of your question, i don't feel qualified enough to answer, leave it to the experts.


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## arthur kierski (Mar 27, 2010)

Samuel, unfortunatelly i cannot send a picture of the wire(i do not have a camera)---i will get a camera soon to complement some of my threads
what i can tell is that it is a fine copper wire where jewellery is hangued in a rh plating solution---as the jewellery is plated with rhodium, the copper wire in the bath is also plated---as the wire is used repeatedly,it becames thick with rh plating
regards and hag samear
Arthur


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## samuel-a (Mar 27, 2010)

thank you, and... thenk you


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## Palladium (Mar 27, 2010)

arthur kierski said:


> although nitric acid here is relatively cheap compared with other countries(110 dolares per 50litres),i was thinking of using ar
> Arthur



Do you Mean AP Authur ?


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## arthur kierski (Mar 27, 2010)

Palladium,i meant ar because ar does not dissolve rh
thanks for letting me make it more clear
 Arthur


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## Palladium (Mar 27, 2010)

I understand. Why not use AP if all you have is Copper and Rh ?


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## arthur kierski (Mar 27, 2010)

Palladium,thanks for the idea----i will try with ap
do you have an idea of how much hcl and 100 volume h2o2 needed per kilo?
my h2o2 is very strong -----


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## qst42know (Mar 27, 2010)

Ap is started with 3% peroxide first aid disinfectant, and kept going with aeration.


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## arthur kierski (Mar 27, 2010)

qst42know,3%h2o2 will take years to dissolve 1kilo of copper wire----if so i will do the dissolution with 3,5litres of hno3 plus 3,5 litres of h2o per kilo


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## qst42know (Mar 27, 2010)

The peroxide just starts the reaction. Copper chloride is the active ingredient that attacks the copper. Once started it will run until saturated.

Have you read the CuCl document on Lazersteves website? It explains this better than I can.


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## arthur kierski (Mar 27, 2010)

qst42know,i did not read lazersteve site about cucl,i will read now----thanks for the information-----regards
Arthur


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## Palladium (Mar 27, 2010)

http://www.scribd.com/doc/29035575/Peroxide-Acid-Method


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## samuel-a (Mar 27, 2010)

qst42know , arthur has a point there.
AP will take months to completly dissolve the copper, even with bubling and constant agitation.

i don't know how much AR affecting Rh, if not at all then it might be a good idea, but if it is dissolving some Rh, then the 50/50 nitric is the ulimate solution to my humble opinion.

one more thing, that i'm a little afraid to suggest is... maybe you can try a copper sulfate cell, it will sure save you on chemicals. although wires might be problematic media and will take long time as well. *i *would give it a go..... but that's me... :mrgreen:


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## Palladium (Mar 27, 2010)

It want take but a couple of days with the right set up. I can do it in 3 days if not quicker. According to how thick the wire is.


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## Oz (Mar 28, 2010)

Arthur,

In this case if AR is cheaper for you than straight nitric I would use it. I have boiled rhodium foils in AR for over 4 hours to no effect. It is possible for some Rh to go into solution with AR but as long as you treat your acid wastes by the stock pot method you will recover any miniscule traces that may have gone into solution. 

Considering the volume of material you have and its metals, I would just keep feeding your material into AR until the acid is exhausted and you will have your foils and any Rh that may have gone into solution will be a fine cemented powder due to cementation on your copper. It is worth driving this reaction by boiling near the end of the acids life to be sure it is truly exhausted. Also be sure that at the end when you kill the heat you dilute your solution with water before it cools or you will be dealing with copper chloride crystals forming with your foils and possible cemented Rh. The solubility of your copper in a chloride solution is greater at a higher temperature than it is cold. You will also find that if you add room temperature water too quickly to hot concentrated copper chloride solution that you will form white copper 1 chloride solids, if you do it is easily washed out of your filtered and saved solids with HCl.

Have fun!

Edited incorrect wording


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## Harold_V (Mar 28, 2010)

Oz said:


> It is possible for some Rh to go into solution with AR but as long as you treat your acid wastes by the crock pot method you will recover any miniscule traces that may have gone into solution.


Crock pot method?

Surely you mean "stock pot"?

They are not one and the same. 

Harold


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## Oz (Mar 28, 2010)

Yes, I indeed meant stock pot. Oddly enough in another thread you wrote a correction in I just mentioned how important it is to be exacting. 

By all means keep nitpicking us all Harold, it is a necessary component for the forum. I only wish everyone saw this instead of sometimes taking it personally when corrected.


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## Harold_V (Mar 28, 2010)

Oz said:


> Yes, I indeed meant stock pot. Oddly enough in another thread you wrote a correction in I just mentioned how important it is to be exacting.
> 
> By all means keep nitpicking us all Harold, it is a necessary component for the forum. I only wish everyone saw this instead of sometimes taking it personally when corrected.


We all screw up occasionally, Oz, myself included. The best we can hope for is someone that is knowledgeable bringing it to our attention. 

Frankly, if a person's ego is so large that they can't be told, I have no interest in conversing with him/her. 

I rarely allow misinformation to stand, and hope that when it's my turn to say something stupid, that someone would step forward with a correction. I would also hope to respond with a heartfelt "thank you" for the correction. 

Reason? 

One learns nothing by talking. 

Harold


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## Oz (Mar 28, 2010)

In this case I simply miss-wrote the word and it did need correcting, thank you. I try to be as accurate as possible in what I write, but my feelings as to being wrong is that every time I found out I was, I have just learned something new. There is little room for egos when working with dangerous chemicals.

I hope Arthur finds value in what I said now that it is corrected.


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## goldsilverpro (Mar 28, 2010)

Arthur,

Were those plating wires used only once or were they used for multiple cycles? If multiple cycles, there could be alternating layers of nickel between the Rh layers. You said you got higher yields with nitric than with AR. Maybe all the Ni wasn't leached out with the nitric, whereas it was with AR. If it wasn't real hot, that could happen. Test the Rh foils from the nitric with a good magnet to see if any Ni is present. 

If they are gold plating also, there could be some gold layers there that aren't touched with nitric but are dissolved with AR. In this case, though, you would probably see the gold color.

If some Rh is dissolving with AR, maybe you can prevent this by diluting the AR a bit with water - say, 25% water. Even dilute, it should still quickly dissolve the Cu and Ni. Play with some samples.


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## arthur kierski (Mar 28, 2010)

thanks Oz for rememorize to me that rh foils will not dissolve in ar----i work with rh for sometime and also boiled rh powder in ar for hours to put in solution any impurities(in this case base metals and au,pt ,pd)and no rh was dissolved--------------
just to mention:i make a ar solution (4hcl to 1hno3+2litres of water) and dissolve rapidly 1kilo of the wire in a plastic bucket---no heat is needed-------
as i do not have the expertize yet to do the ap method that palladium mentioned,i will get the rh foils with ar------
thanks all for reading this thread and the wonderful sugestions that was passed to me
Arthur


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## arthur kierski (Mar 28, 2010)

Gsp,the plated wires are only plated with rh--sometimes the wire is used many times,but just for rh plating
the fantasy jewellery that i did last year with ar ,certainly had ni under the rh plating and certainly some rh went to solution(when rh is in form of alloy it dissolves in ar)---thanks for the questioning -----
next week i will receive some fantasy jewllery (with defects) and for all you mentioned i will obtain the rh foils with nitric acid---
thanks once more for clearing my mind with my doubts
Arthur


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## fenzers (Apr 12, 2011)

Hi

I'm new to the forum and do not understand some technical words used by you.
I have a small GALVANICA in Portugal and I use copper wire to hold the pieces are rhodium plated. My question has to do with being able to recover the rhodium that same copper wires. I usually sell the copper, but that only gives 5 € / kilo, and I think he earned more while recovering rhodium. The copper wire has no nickel, rhodium bath only.
Is it possible to explain to me all the steps to rhodium recovered not in copper wires?
Best Regards

Marcio


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## goldsilverpro (Apr 14, 2011)

Welcome to the forum, Marcio.

You have only copper and rhodium. Simply dissolve the copper and you would be left with fairly pure rhodium. Since rhodium plating is highly stressed, it will most likely break up into small slivers. There are several ways of dissolving the copper. The most common would be nitric acid or a combination of HCl and hydrogen peroxide, both of which are covered in detail on this forum.

Chris


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