# pgm seperation as part of dissolving process from cats



## pip (Feb 14, 2009)

Since the three PGM's in a converter can be dissolved in different acids would it be possible to chemically seperate during the dissolving process?
My thinking is since only Rhodium dissolves in Hot sulfuric acid and only Palladium will dissolve in Hot Hcl then this seperation will work?

1. boil converters in sulfuric to collect Rhodium then remove sulfuric + rhodium

2. boil converters in hcl to collect palladium then remove hcl + palladium

3. boil converters in Aqua regia to collect platinum 

I am more concerned with easy seperation than using as little acid as possible.


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## arthur kierski (Feb 14, 2009)

very ,very dificult idea to executate-----pd is mostly in metalic form,so hot conc hcl will not put it in solution(only the oxide form will dissolve)----conc h2so4 needs to be heated at 500centigrates to dissolve part of the rh present(if it dissolves in this conditions, i doubt)----the hot ar will dissolve all the pd(not pdoxide),all the pt and part of the rh that oxidized during the cats life------so your cat will still have pdo and rh in its substrate---- but your idea gave me an idea that i will develop and then write about it


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## pip (Feb 14, 2009)

Thanks for the reply and let me know when your idea is ready.


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## Irons (Feb 14, 2009)

Palladium dissolves in Sulfuric as well.


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## arthur kierski (Feb 14, 2009)

as iron mentioned,pd will also dissolve in sulfuric---


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## jsargent (Feb 14, 2009)

PM acid solubility chart: http://www.platinummetalsreview.com/jmpgm/data/image.do?img_id=710&database=cesdatabase


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## pip (Feb 16, 2009)

this has nothing to do with the original post but i can't find the answers on the site so i figured I'd ask without starting a new thread:

i took 5 american cats ans disolved them in aqua regia made with the shore sub zero product. after 3 months in the bucket i drained, filtered , and boiled the liquid down to 1000ml. last week i boiled it to 500ml. the liquid is not viscous but is really hard to get to boil down. after sitting for a week at 500ml there is a new precipitate at the bottom that formed out of nowhere. it seems to glitter and is whiteish and the aqua regia no longer smells like chlorine. 

what precipitated? 

does smb precipitate all pgm's because i have that and want to know if i can use if before i try.


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## lazersteve (Feb 16, 2009)

It's sodium chloride from the HCl and sodium nitrate.

Rehydrate, adjust pH to 3-5 and add zinc to precipitate mixed PGMs.

Steve


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## pip (Feb 16, 2009)

thank you steve


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