ChuckNC - 28-7-2006 at 01:27
Hi guys.
This might be a little off the wall, but as Au and Ag are soluble in a basic solution of CN, are Platinum Group Metals? I have heard about it being
done, but at what temps and pressures?
Anyway, I have a feeling it's not for the small guy.
I am familiar with using CN, it's hazards, how to neutalize and dispossal also.
Any info would be appreciated.
Chuck
Fleaker - 28-7-2006 at 10:03
To my knowledge Chuck, cyanide will complex with platinum but not to the convenient extent that gold and silver do. KCN is used more with Ag and Au
for that reason, with leaching/floatation being common treatment for ores. I've never worked much with cyanide solutions but for plating baths.
Cyanide appears to be of limited utility when working with platinum as many prefer to use halide/sulfuric acid route, which is in many ways, an
aqueous version of gas phase transport via halogen gas (where the halogen serves as the oxidizing agent)
This link, if it works, might be of interest:
http://doc.tms.org/ezMerchant/prodtms.nsf/ProductLookupItemI...
This is the sulfuric acid/oxidizer/halide ion method which works well for platinum and in particular rhodium from catalytic converters:
http://www.freepatentsonline.com/5304359.html
Edit--Welcome to the Board!
[Edited on 28-7-2006 by Fleaker]
ChuckNC - 30-7-2006 at 19:04
Thanks for the welcome Fleaker.
First link won't work for me. Second one is very interesting.
Chuck
Chuck:
Vitus_Verdegast - 30-7-2006 at 19:51
try this for the first link:
http://tinyurl.com/z94a4
JohnWW - 31-7-2006 at 17:58
I thought that aqua regia (HNO3 + HCl) was standard for dissolving platinum group metals.
not_important - 31-7-2006 at 18:43
They have been, but on a large scale the off-gassing is a problem, the acids are relatively costly, and for some processing you need to evaporate down
the solution, add more HCl, evaporate, and so on to remove nitrate. Aqua regia is still good on a small scale, but industrial types have been
considering alternatives for years..
Which brings up a possible reason for not using cyanide. In many cases you are dealing with a mix of the platinum metals, either alloys and/or mixed
scrap. From what I remember many of the separation schemes take place moostly in acid solution and/or with halides.
Fleaker - 2-8-2006 at 09:57
Also JohnWW, aqua regia has to be heated to dissolve platinum, at room temp, it barely affects the metal. Works excellently for gold though.
Remember Chuck, always work with basified cyanide solutions!
jokull - 3-8-2006 at 08:11
Hi Chuck!
I'd like to know what material are you interested to complex platinum from. is it a solution? an alloy?
Is it really necessary to use cyanides?
ChuckNC - 7-8-2006 at 19:13
Jokull,
Mainly I'm interested in stripping catalytic converters and a deposit I have found. I'm intimately aware of using Aqua Regia, but was looking at CN
only because it does so well on Au and Ag. It's not needed, but I had read somewhere about the pressures and temps needed to digest PGM's in CN and
wanted to see if anyone here was familiar with it.
Mainly just a quest for a little knowledge.
Chuck
ChuckNC - 7-8-2006 at 19:19
Well after studying the supplied sites, I'll stick with AR. Simple and easy to use, and I don't need to use extra electricity to recover the Pt and
Pd. I will keep it in mind for the Rh though.