Gold fill over Brass

[Shark]

This is one of the many reasons to have and learn to use more than precipitant. That white looking material appears to be excess SMB, although it is hard to tell from the pictures. Stannous chloride and PH papers would go a long ways to figuring this one out.

 

[dofustofy]

Both samples worked using the HCI / Bleach method

 

[dofustofy]

This is one of the many reasons to have and learn to use more than precipitant. That white looking material appears to be excess SMB, although it is hard to tell from the pictures. Stannous chloride and PH papers would go a long ways to figuring this one out.

Shark, you are right. That was way to much precipitate in that solution. It was also to much nitric as Yggdrasil had mentioned. However this Gold being what it is Brazilian golf fill over brass I will just use the HCI / Bleach method for this type of material. The Gold fill I get here at home has a higher percentage of Gold and I have mot had any issues using Nitric. Its only been an issue with the Brazilian gold fill.over Brass.

Thanks guys for all your support.

Dustin

 

[dofustofy]

Shark, you are right. That was way to much precipitate in that solution. It was also to much nitric as Yggdrasil had mentioned. However this Gold being what it is Brazilian golf fill over brass I will just use the HCI / Bleach method for this type of material. The Gold fill I get here at home has a higher percentage of Gold and I have mot had any issues using Nitric. Its only been an issue with the Brazilian gold fill.over Brass.

Thanks guys for all your support.

Dustin

Until now.

 

[Shark]

Have you tried doing it in AP? It works pretty well, just takes longer.

 

[Martijn]

Until now.

i would check your stockpot with stannous and look for and then test some residue

Lets assume for a moment there is to much nitric can I use sufamic acid to reduce the nitric acid? I was sure to boil off all the excess nitric but, maybe not. On the small amount I have in my test beaker I just added SMB and I noticed nitric oxide fumes coming from the reaction.

The best solution to solve excess oxidizer in you AR, is dissolve more gold. the reason you can't get it out, is you've use too much nitric. Reuse it wise and save on time and money.
The stockpot residue would be a good option to consume your excess nitric. no sulfamic needed. Add slowly, powders can react violently!

If you have no more gold to dissolve, some very fine copper powder will consume that nitric fast and then drop your gold. Add it slow at 50 degrees C. vent well.

 

[dofustofy]

Have you tried doing it in AP? It works pretty well, just takes longer.

Yes, and you were right. Works perfect. Thanks.

 

[dofustofy]

i would check your stockpot with stannous and look for and then test some residue

The best solution to solve excess oxidizer in you AR, is dissolve more gold. the reason you can't get it out, is you've use too much nitric. Reuse it wise and save on time and money.
The stockpot residue would be a good option to consume your excess nitric. no sulfamic needed. Add slowly, powders can react violently!

If you have no more gold to dissolve, some very fine copper powder will consume that nitric fast and then drop your gold. Add it slow at 50 degrees C. vent well.

I do have residue in my gold refining waste containers. Thats a great idea. I will give it a shot and get back to you. Thanks!