# Cyanide



## dmarth10 (Oct 28, 2008)

Is H2So4 and NaCl a cyanide prodess for leaching? I was reading a site about an experiment on catalytic converters. If its cyanide, Im not trying it, otherwise...

The site is:

http://findarticles.com/p/articles/mi_qa5348/is_/ai_n21328741

David


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## Anonymous (Oct 28, 2008)

H2SO4 is Sulphuric acid
NaCl is sodium chloride or table salt
Therefore there is no cyanide in this leaching process.
As to how safe this process is, I will leave that to one of the chemists on the forum to answer


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## dmarth10 (Oct 28, 2008)

I know what H2So4 and NaCl are. I do believe that in this process cyanide is produced. Is that false?


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## Anonymous (Oct 28, 2008)

I wasn't trying to teach you to suck eggs and apologize accordingly.

I have read through the process you linked to and the way it reads to me is that it is a work around process avoiding the use of cyanide much the same as the AC process works around the use of Nitric acid.


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## butcher (Oct 29, 2008)

sulfuric and table salt would produce HCl (hydrochloric acid)(muratic acid) fruit seeds have cyanide in them, sulfuric and salt would not produce cyanide,havent read the process but I think you would also need a strong Oxidizer, or another chemical like nitrate for it to dissolve the PGM's


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## Lino1406 (Oct 30, 2008)

Is the extractor for Rh, from handbook
of chemistry dated well back. Mr Mahmoud
has replaced HCl with NaCl, and as expected,
this worked also for the less vulnerable Pt and Pd.
He did a great job, since expecting is not the same
as validaing. Cyanide is another method - no mingling
at all. And cyanide would not work for all PM's


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## Lino1406 (Oct 30, 2008)

In last message, "less vulnerable"
should read "more vulnerable"


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## qst42know (Oct 30, 2008)

They are processing catalysts from the production of fertilizer. Not automotive cats. Essentially they are adding sulfuric acid and NaCl creating HCL, the nitric exists in their catalyst. 

They are creating a 3 acid blend of Aqua Regia and Sulfuric. This blend may work as well on automotive cats.

It was stated that when their material was rinsed they did not recover values as well due to removing the nitric.

A question to the chemically minded members of this group.

Would *wet ashing* remove the carbon from automotive cats more efficiently than roasting, allowing improved PGM recovery?

Is anyone set up to try this?


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## Lino1406 (Oct 30, 2008)

removes lot of carbon


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## lazersteve (Oct 30, 2008)

I agree with Lino,

A simple water washing is all I would do, and that's only if the cat is really bad off. 

Steve


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## qst42know (Oct 30, 2008)

Does carbon interfere with the recovery of PGMs chemically. Rhodium in particular. Or is it just a bothersome contaminant in the solutions.

Perhaps I misunderstood why the carbon should be removed.


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## lazersteve (Oct 30, 2008)

My yields have been very close either way and I routinely don't wash them or roast them.

When I first started working with cats I did roast, but I have since stopped roasting. If one is really caked up I'll spray it out with water really well then let it dry before I leech it. Either way you will need to filter the resulting leech completely free of this carbon before you proceed. My new PGM DVD will demonstrate the entire process.

Steve


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