rhodium plated over copper wire

[arthur kierski]

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

 

[samuel-a]

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.

 

[arthur kierski]

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

 

[samuel-a]

thank you, and... thenk you

 

[Palladium]

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 ?

 

[arthur kierski]

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

 

[Palladium]

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

 

[arthur kierski]

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 -----

 

[qst42know]

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

 

[arthur kierski]

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

 

[qst42know]

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.

 

[arthur kierski]

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

 

[Palladium]

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

 

[samuel-a]

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:

 

[Palladium]

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.

 

[Oz]

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

 

[Harold_V]

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

 

[Oz]

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.

 

[Harold_V]

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

 

[Oz]

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.