redish orange/brown color in nitric solution

[cad]

I Have another color in my nitric wash It is redish/orange brown and thick. there was a great deal of silver that i use hcl to drop and filter out but the color remains. This is a new one for me.

Carl

 

[lazersteve]

Test with stannous for gold and PGMs.

Steve

 

[cad]

It is still filtering very slow. when its through i will try stanus again.
I was not aware that in nitric that much gold or pgms could be put in solution.

Carl

 

[butcher]

if it filters slow that junk can hold fine powders, or colloids
did you have any tin or aluminum or other metals that would give trouble and trap values?
if you added Hcl to nitric wash to drop Ag you made aqua regia to dissolve gold.
I may be misunderstanding what you did here.

 

[Harold_V]

I Have another color in my nitric wash It is redish/orange brown and thick. there was a great deal of silver that i use hcl to drop and filter out but the color remains. This is a new one for me.
Carl

The color you described could be palladium. Depending on the source of your material, it wouldn't be beyond possibility that's what you have. It also wouldn't be beyond possibility that you have dissolved some iron along the way.

Testing with stannous chloride will yield a strange reaction, ranging from blue through green, and may even change from one color to another, if you have palladium present. If you get a color reaction and you're not sure what it means, test with DMG, which will yield a strong yellow precipitate, even when there is little palladium present. If you have palladium and you test with DMG, the color of your solution should change upon precipitation of the palladium. It then will reflect the base metals that are present, and the brown color should be gone.

If your source included any dental alloys, it's entirely possible you have both palladium and platinum present. It's usually a good idea to suggest what you've been processing to help identify the potential materials.

Harold

 

[cad]

I am not sure all of what was in the material that i put in the nitric wash. It turned the redish pretty quickly.
I filtered the fluid and findings before i added hcl to drop silver and then filtered out the silver nitrate. I do get a yellow outside ring with stannus. I guess my next step would be to kill the nitric and try to drop things out.

carl

 

[Harold_V]

I am not sure all of what was in the material that i put in the nitric wash. It turned the redish pretty quickly.
I filtered the fluid and findings before i added hcl to drop silver and then filtered out the silver nitrate. I do get a yellow outside ring with stannus. I guess my next step would be to kill the nitric and try to drop things out.

carl

That doesn't sound encouraging. I am not familiar with a yellow indicator using stannous chloride. At best, you may have a solution with traces of platinum, but the reaction would be in the entire solution, and it would lean more orange than yellow. Assuming you did have traces of platinum present, you won't be able to recover them by precipitation. Platinum and palladium will not precipitate from solutions in low volume, but it could be recovered in the stock pot, or even on copper. Unless you have a huge volume of solution, I'm inclined to think it's a waste of your time, however. The presence of platinum in a reasonable volume would yield a nice orange to brown color, not yellow.

If you have excessive nitric, it's possible your test won't be conclusive, but if you don't find evidence to support the presence of any particular metal, going through the exercise of precipitating any of them will be for nothing. Stannous chloride, assuming it's not too old, does not lie.

Harold