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Author: Subject: Rh bath - cleaning
midas
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[*] posted on 17-5-2006 at 00:26
Rh bath - cleaning


Do you know of the cleaning of Rhodium bath after jewellery processing?

and I would like to ask also that copper or zinc sweeping from the rhodium bath by the means of the Chramatography?

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enhzflep
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[*] posted on 17-5-2006 at 02:57


What exactly do you mean midas?

Is your bath contaminated?

If so, best option is to tip down drain or retain for future recycling with (many, many) other such baths.

Platinum has over 200:o process from ore to ingot, I'd suspect rhodium to have a
similar or greater number, based purely on it's price (not very scientific, I know)

If you've got 1/2gms per liter, then just forget it for 1L. I know several refiners that
refuse to touch the stuff. They'll refine the gold from such mixtures containing Pt or
Pd, but on a non-industrial scale it's just too much of a headache.

LOL, - I accidently ran reverse polarity one monday morning for 2-3 seconds on a 1 week old bath and our refiner still wouldn't touch it. Shit! There went $200!!!

You could probably do some form of High Performance Gas Chromotography on a
sample, but IIRC its about $1000 for CSIRO to do something like that. :(
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[*] posted on 17-5-2006 at 10:11


I'm not saying that nobody would do Gas chromatography on a bunch of metals like Rh, Zn and Cu, I'm just saying that they would only do it to show off that they could.
Ion chromatography would seem to make more sense if you wanted to analyse the stuff or to purify it (Though I wouldn't like to design the purification scheme).
Midas, I guess that English isn't your first language. Where are you from?
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midas
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[*] posted on 22-5-2006 at 21:41


Hello my friend; Enhzflep
How are you?

First of all than you for replying my questions and kindly answers,



I am depply interested in refinin rhodium bath. Could you tell me one of refining process that I may use. I have an setting in my mind, for example, I will use the glass tube, and put into a piece of cotton, and pour the rhodium bath to glass tube through the cotton part. And I am looking for any chemical solution for holding copper, silver, zinc, gold in the cotton. so finally I have pıre rhodium bath. I am looking just for chemical.



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enhzflep
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[*] posted on 23-5-2006 at 02:44


Hmmm - mmmmmm -mmmmmmmmm.
Yeah, not bad my friend.
No problem.

In a word, no.

The problem is that the rhodium salt present is a rhodium sulfate of some description. In order for the bath to keep plating reasonably bright, one needs to maintain rather acidic conditions..

Any copper/zinc particles that fall in will be digested, i.e turn into copper/zinc sulfate - in solution :(

After that monday morning, I too was rather keen to find out how to refine the solution. A number of close associates (all refiners) were not able to tell me how to do this.

This conversation was some years ago now, and I really don't recall.
From memory you may have some luck using fractional electrolysis. The problem was if I recall correctly, that it is rather difficult to get various metals to plate out seperately. Not to mention the plating out of the rhodium, or the decomposition of the (purified) rhodium salt without oxidising the metal.

I'm not aware of a way to precipitate the rhodium from solution in the same way that one may use ferrous(ferric?) sulfate to precipitate gold from aqua regia.

As I mentioned above, in spite of knowing several refiners personally, I was unable to recover the bath that I ran reverse polarity through that monday morning - which cost me roughly 1 week's pay at the time.
Although, we did have a black rhodium bath after that...... :D

At ~$700 Aus for 2grams in 100ml solution its not the cheapest stuff to be playing with.

If you manage to find out I'd love to know.

(After that we moved onto Pt plating bath. Is just as good for practical purposes, much, much cheaper, AND you can easily make it yourself:))
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midas
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[*] posted on 23-5-2006 at 07:11


Hi!
I did experiments with ferrous(ferric)sulfate. I used hull cell test.

1. old Rh bath
2. old Rh bath +2 g / lt ferrous(ferric)sulfate
3. old Rh bath + amply ferrous(ferric)sulfate

Result :
1. gray and mat
2. white-gray and bright
3. gray and bright

Fe and Rh is plating together aloy. İn your opinion?
You are learned this work.
Now, will I to escape Fe? 
Thank you
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midas
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[*] posted on 23-5-2006 at 07:29


Thanks unionised
I will explore ion chromatography.
Yes, English isn’t my first language and my english is bad.
I am from Turkey/İstanbul.
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