# Rhodium refining



## pgm (Feb 7, 2011)

Hi

i was told Rhodium will not be touched by AR....i have since sent a sample to the assay office to have it checked. i still can not wait for the answer it has been a few weeks so should get an answer very soon. in the mean time i wanted to ask about rhodium SAY there was some left in the ceramic material, how would i go about getting this out. The text below is what i found while searching....now i understand this concept but what if i do not have access to a fusion oven...

any other way?....
will this fusion work with pt and pd or is it rhodium 

"If the ceramic contains rhodium, it is put into reaction with NaHSO4 in the fusion oven, and rhodium is transformed into RhSO4. RhSO4 is dissolved in water and so is separated from ceramic; the solution is filtered and taken away, and rhodium is recycled from this solution by precipitation"

what other chemical mix will work in the leaching process?


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## dtectr (Feb 7, 2011)

i just read that rhodium is soluble only in HOT concentrated sulfuric ...


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## pgm (Feb 8, 2011)

dtectr said:


> i just read that rhodium is soluble only in HOT concentrated sulfuric ...



must be another wet process...what will contain hot sulfuric not the plastic bucket...can not heat in that.


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## skippy (Feb 8, 2011)

Palladium and Rhodium both dissolve in hot concentrated sulfuric acid. And by hot, that's about 300C. The sulfuric has to be boiling, or nearly so. Borosilicate can survive such temperatures, but cracking is a possibility, another possible material is quartz, another cast iron. Iron passivates in concentrated sulfuric acid. There's some rather important safety concerns, if you've seen how hot sulfuric acid get when it mixes with water at room temperature, it's going to be much more aggresive at 300C. I wrote a little about my experience with using hot sulfuric in a couple of recent posts I made in the PGM section. 

The fusion you mention has a similar mechanism to the sulfuric attack, and it releases nasty SO3 fumes, like the sulfuric does. You could modify a pottery kiln for a fusion, but you would need to make or get some sort of reaction vessel to contain the material and to conduct the fumes outside of the furnace, where they could be scrubbed.


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## pgm (Feb 8, 2011)

skippy said:


> Palladium and Rhodium both dissolve in hot concentrated sulfuric acid. And by hot, that's about 300C. The sulfuric has to be boiling, or nearly so. Borosilicate can survive such temperatures, but cracking is a possibility, another possible material is quartz, another cast iron. Iron passivates in concentrated sulfuric acid. There's some rather important safety concerns, if you've seen how hot sulfuric acid get when it mixes with water at room temperature, it's going to be much more aggresive at 300C. I wrote a little about my experience with using hot sulfuric in a couple of recent posts I made in the PGM section.
> 
> The fusion you mention has a similar mechanism to the sulfuric attack, and it releases nasty SO3 fumes, like the sulfuric does. You could modify a pottery kiln for a fusion, but you would need to make or get some sort of reaction vessel to contain the material and to conduct the fumes outside of the furnace, where they could be scrubbed.



thanks for the feedback....i am learning all the time...i will get there very soon


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## Lou (Feb 9, 2011)

It will dissolve in aqua regia.


Lou


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## pgm (Feb 9, 2011)

Lou said:


> It will dissolve in aqua regia.
> 
> 
> Lou



Lou i really hope you are right, this will then save me doing another process with the honeycome. i have been waiting for a reply from the assay office but nothing as of yet but should get something back this week.

do you think it is best practice to incenarate the honeycome and ballmill it to get the best results?


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## Barren Realms 007 (Feb 9, 2011)

Wash it with a heavy stream of water then ball mill it and then process it.


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## pgm (Feb 9, 2011)

Barren Realms 007 said:


> Wash it with a heavy stream of water then ball mill it and then process it.



thanks i was thinking of giving the whole honeycome a bath, to get ride of the dirt and oil....giving them a good clean before the ball mill. i have read roasting helps burn of the oil and the leaching goes pretty good after this is done...but need to try this to confirm...

will update as i do


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