# sulfuric acid +nacl in cats substrates



## arthur kierski (Mar 29, 2008)

i did this experiment twice and obtained the folowing results:500gms of substrate gave 0.44grams of rh and 0.41grams of palladium---not a single gram of platinum.
i read in this forum that someone did the same experiment and got platinum and was surprised that he did not get any palladium.
to the substrate left i made a strong ar+10%h2so4+20%hf---i do this for 72hours and in cold,the solution is extremelly red and monday when ends the 72 hours i will extract the pgm in this solution.
i would like feed backs from you---any information from you will be welcome.
thanks,Arthur kierski


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## Lou (Mar 29, 2008)

How do you know that it is rhodium, and not platinum? Tell me Arthur how you distinguish them? Your recovery values sound right for a decent converter except for the rhodium--I don't see how 0.88g Rh/kilogram converter would work...

I think your procedure is lacking a few details--you're not telling us everything.


Personally, I would not make a leach out of it--I would just dissolve away the substrate with that 20% HF then process the PGMs. The Pd and Pt are removed with AR, the Rh should be relatively pure, but can then be fused to give rhodium sulfate and sold as plating solution, or it can be plated out onto Rh wire, or you may process it further to another more easily reducible salt.


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## arthur kierski (Mar 29, 2008)

Lou,thanks for your replyes and questioning---just for your knowledge i have to tell you that i extract rhodium from cats,fantasy jewellery and other things like the threads that holds the pieces for plating etc...etc.
in the last 3years i did not buy a single ounce of rh---i use 80 to 100grms
of rh monthly to make rhsulfate plating solutions---i used to buy rh sponge from Kitco.
After 2hours in the h2so4 (60%) +6grams nacl per 100ml at 135+or-C--i filtrated the solution and added 100grms of iron powder-it dropped 3.52 gms of pgm+impurities like--sio2 +pb--to this 3.52 grams i
used aquaregia which i evaporated 3 times with hcl ---to the liquid left i added a concentrated kcl solution to drop platinum(kcl is used instead of
nh4cl because it drops only platinum ,os, and ir---separating rh and pd which stays in the solution)It did not give pt---to the solution left i added 
hidrazine and droped black rh and pd----to this powder ar was added and the black rh remained(0.21grams) the liquid gave 0.43grams ofpd-----------------------after the aquaregia digestion the powder left was 1.59gramms which i added pure hf to kill the sio2 and pb--filtered and dried the 1.59 grams who became 0.23grams of rh--so here is my 0.43grams of rh and 0.43 of pd----it adds to 0.86 because i did in my lab and i am at home doing this reply by memory


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## arthur kierski (Mar 29, 2008)

lou, i agree on you remarks of adding 20%hf and then leach with ar---problaby will do it monday---Thanks


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## Froggy (Mar 29, 2008)

platinum smatnlum, thats $125 for a lb of converter material for the rh alone, if this converter is 3lb then you are getting $375 in rh per converter!!!! and I know how cheap southern hemisphere converters are. but I do wonder where your pt is going, are these pre- converters?


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## arthur kierski (Mar 29, 2008)

Froggy, they are not pre-converters and as i wrote ,after the h2so4 +nacl leaching, i took the restant substrate +ar+h2so4+hf for 72hours due monday to leach=up to now the solution is very red----I think the pt is in this solution(ar for 72 hours i got many years ago when rhodium was not part from c.w. ammen book)


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## lazersteve (Mar 29, 2008)

Art,

The original article on the salt leach suggest a 10 hour reaction time for 95% extraction of Rh, the two hour time frame should work for Pd and Pt just fine.

Steve


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## arthur kierski (Mar 29, 2008)

Steve,if 2hours would be fine to extract pd and pt, where is the pt from my experiment??how come that i ended up with pd and rh?


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## lazersteve (Mar 29, 2008)

Art,

Did you test your solution with stannous after extraction?

Steve


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## arthur kierski (Mar 29, 2008)

Steve, being honest,i did not test and trew the solution after i precipitated with iron powder.


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## skippy (Apr 10, 2010)

Arthur, I think I solved the mystery - better late than never, right?
The original paper that the NaCl+H2SO4 process came from was using it on catalyst used in the production of nitric acid. The catalyst had nitrate or nitric residue on it, and in the paper it was noted that if the catalyst was rinsed (ie no nitrates of nitric in the material) the platinum extraction was very minor. This would definately seem to match with your results.
So maybe you can add a touch of nitric acid! 

Just make sure to give me half of the platinum you recover with this! It's only fair! :lol:


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