Premature addition of precipitants. Is this a problem?

[henster1379]

Hello, I treated some cat/con powder in aqua regia. I then diluted original 1000 ml solution to 2000 ml, and then filtered twice. The stannous test gave no change in color from original color in the solution which was an amber orange color. tried precipitation with 4N ammonium chloride solution. There was no precipitation in sight i then probably really messed it up by trying to precipitate any palladium in the solution with sodium chlorate without being able to extract the platinum first. I know that I skipped the part of converting the nitrates into chlorides. Can i still fix this or is it to late for an amateur.

All advice is appreciated
Thanks,

 

[butcher]

maybe try reconcentrating it. these salts are water soluble.

 

[Oz]

It is still acidic, cement it on copper.

 

[Harold_V]

I then diluted original 1000 ml solution to 2000 ml

Read Hoke.
Platinum group metals rarely precipitate from dilute solutions.

Harold

 

[henster1379]

Thanks for the suggestions i tried looking up cementing process but got no results. Why did the stannous test not change color?

 

[Harold_V]

Thanks for the suggestions i tried looking up cementing process but got no results.

It's not cementing you are discussing, it's chemical precipitation. You can successfully cement values using aluminum (not recommended) zinc, or scrap steel. It's a fail safe method, but does not recover only the values. Proper precipitation (in theory) does.

Why did the stannous test not change color?

Because you didn't recover anything. It changes color upon extraction. If the color reaction remains, it's because precious metals still remain. The reaction may be somewhat subdued by dilution (from the addition of more fluid), but the color should still be the same. That's why you test---to determine if you have recovered all the values, or not.

Harold

 

[Oz]

Harold, the cementation question would be because of my reclamation comment above.

I will add that a stannous test can show negative even with values in solution if you have not removed the oxidizing chemicals you used to put your values into solution.