# Identify Suspected Platinum Salt



## lazersteve (Aug 24, 2007)

Last night I tested a small sample of metal that I suspected to be Platinum and precipitated the AR solution with ammonium chloride. This is the salt that precipitated.:

[img:887:867]http://www.goldrecovery.us/images/pt_salt.jpg[/img]

Can anyone confirm the orange color of the salt as Platinum Ammonium Chloride ?

Are any of the Palladium Ammonium salts orange?

I hunted the internet for a good photo of the platinum salt and found nothing.


Thanks in advance,

Steve


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## jimdoc (Aug 24, 2007)

Steve,
In the Precious Metals Science and Technology book from IPMI
they show a color picture with crystals on the top and solutions
on the bottom. The platinum chloride and platinum chloride solutions
look very similar. With the crystals the palladium looks a little more 
red or brownish and the platinum an orange-red. It looks like it may be platinum in your picture to me, but palladium is also a possibility,and I think Harold or GSP will be the ones that will know. Jim

In picture left to right are; silver nitrate, gold chloride,platinum chloride,
palladium chloride,rhodium chloride, iridium chloride, ruthenium chloride,
and there crystals on top.


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## lazersteve (Aug 24, 2007)

Jim,

Thanks for the post. You've just given me one more reason to buy that book. I almost bought it the day I was over at IPMI. 

The vials in the photo are of metal chlorides, my photo is a suspected ammonium chloride, the color may be different for the ammoium chloride salts of the precious metals. Hopefully Harold or Chris will confirm the identity of the pictured salt for me.

Steve


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## Harold_V (Aug 25, 2007)

The only color variants with palladium are when you precipitate with DMG, or when you dissolve the characteristic red salt with ammonium hydroxide, and re-precipitate with HCL, at which time it comes out a yellow color, but much lighter than that from DMG. I posted a picture some time ago that shows each of them. You'll find it in the Pt group section of the board. 

Regardless of the degree of purity of solution, when I precipitated palladium, it was always red, but varied in depth of color. It would often be a much darker red, which I attributed to the dirty solution. It would brighten with washing. 

The color of your platinum salt can and will vary widely, which I think you can confirm in Hoke's book. I noticed a distinct relationship between the cleanliness and concentrations of solutions to color. When I re-refined platinum the few times I did so, the salt came down a nice light yellow color. It was often an orange color when precipitated from dirty solutions. 

Take a small sample of your salt and test it with stannous chloride. I'm certain you'll see a platinum reaction (coffee color). Dissolve the tiny sample with a touch of water before testing. 

Harold


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## Platdigger (Aug 25, 2007)

Steve, did you have to bring the AR to a boil while adding the Amonium chloride? Were you able to do this without killing or boiling out the nitric?
Randy


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## lazersteve (Aug 25, 2007)

Randy,

Here's how I made the orange powder:


 I dissolved a very small amount of the suspected Platinum metal in a test tube of hot AR.
 I filtered the orange colored solution and rinsed the filter throughly.
 I added approximately a 1/4 teaspoon of solid ammonium chloride
 I evaporated the solution with heating until the orange powder formed along with solid ammonium chloride crystals.
 After cooling, Iadded, dropwise, just enough distilled water to dissolve the solid ammonium chloride.
 I filtered the orange powder out of the solution.

Steve


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## Platdigger (Aug 31, 2007)

Hmmm, if there was no precip, I wonder if you would have gotten the same orange powder by just evaporating the solution without the addition of the ammonium chloride....?....
Just a thought.
Randy


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## Harold_V (Aug 31, 2007)

That's certainly my thoughts. Nowhere have I ever read to precipitate platinum by that method. Could be that it works well enough, however. It would be easy enough to conclude that it does, or not, by calcining. If no metal comes from the process, it can then be safely assumed that it's a mistake. 

The one question I'd have, assuming it worked as it appears, is how selective it might be. In the presence of other metals, were they left behind? If they, too, form crystals, not much would have been accomplished in the way of selective precipitation, which is the real purpose of going through the exercise of dissolving the metal in the first place. 

I'd be interested in hearing about the process of calcining and melting. 

Harold


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