Aqua regia a lot of SMB...

[Yggdrasil]

If you have any axes nitric yes because once you start precipating gold .it will drop and redesolve in same time more you add smb more drop and redesolve because you still have aqua regia working .and in the end you have problems either to much salt your value is not going no where it can be recovered.urea will kill nitric or most part of it .there is some vedios you can watch in YouTube to give you an aidea

Urea is the wrong chemical for this.
It only temporarily remove parts of the problem and under certain conditions may create explosive compounds.
The best to use is Sulfamic acid in a hot solution, it converts any Nitric and NOx to Sulfuric acid.

 

[goldshark]

Maybe a quick description of what using SMB in a high Nitric environment does, by a chemist. Such as ,if you don't use Sulfamic to neutralize excess nitric, but keep adding SMB till it starts piling in heaps at the bottom of the beaker, but no Gold powder, or gold powder appears , then disappears time and again,despite adding even more SMB till it overflows the beaker. I did this once, laugh about my stupidity now. This is what I like about this forum, people are patient. They answer questions that could be obtained by a comprehensive reading of Hoke's. Thanks all for our patience.

 

[Yggdrasil]

One can always bubble SO2 through the solution.
It will sooner or later deplete the Nitric without adding much to the solution.
It may however require a boatload of SMB to generate the SO2

 

[Alexander_Hun]

Looks great use stanous chloride make sure there is no gold left in AR

I made stannous chloride, it works very well

 

[Biom]

I made stannous chloride, it works very well

Good luck great .stanous chloride it's your eyes in refining .you can progress better without loosing any gold

 

[Alexander_Hun]

Hello, when melting gold, what causes the gold to change color as it cools down? At the bottom, where the jar was, it is a beautiful yellow, at the top it looks like copper. But this is only on the surface, it disappears with more melting.

 

[Martijn]

Impurities like copper oxide. Sprinkle a little borax at the end and see if disappears.
Are you using a clean crucible?

 

[Alexander_Hun]

Impurities like copper oxide. Sprinkle a little borax at the end and see if disappears.
Are you using a clean crucible?

Hi, unfortunately I melt it together with filter paper, it's not completely clean, but I didn't melt any other material in it, only gold. I use borax, if I throw it in acid afterwards, it will become lighter after a while

 

[Shark]

if I throw it in acid afterwards, it will become lighter after a while

Only on the outside. The inside of the gold will still contain some copper. Sometimes one or two grains of sodium nitrate or potassium nitrate added to the melt will remove small amounts of impurities. It is best to remove them in the refining. Better filtering along with better washing of the gold powders will make large increases in gold quality.

It is possible that these impurities added to your gold floating in your original post.

 

[Alexander_Hun]

Only on the outside. The inside of the gold will still contain some copper. Sometimes one or two grains of sodium nitrate or potassium nitrate added to the melt will remove small amounts of impurities. It is best to remove them in the refining. Better filtering along with better washing of the gold powders will make large increases in gold quality.

It is possible that these impurities added to your gold floating in your original post.

If copper also dissolves with gold in the AR, will only the precious metals separate out during the reduction? Does it affect the final quality?

 

[Shark]

When the gold drops some amount of copper will drop with it. An excess of SMB will cause more copper to drop with the gold. One way to stop this is to remove most of the copper before using AR. A bath in hydrochloric acid for a few days will remove copper. Also a bath in nitric acid alone will work. Just use one for the first time allowing it time to work. Remove the acid of choice, then proceed to AR.

My preferred method is to drop the gold and wash the powders well. I use three boiling water washes, then a boiling hydrochloric acid wash, then again with three boiling water washes. Repeat until the acid wash shows no signs of discoloration. Then I go back to AR and repeat it all over again.

All of this can change depending on the material I am running, and what the expected contaminates may be. Good filtering is important also to the removal of many contaminants in the refining.

Very careful with boiling acid, it very unforgiving.

 

[Biom]

Smb very selective for gold .you may have some drag down .it's very important to clean the powder to high purity before melting .you may use some sodium bicarbonate see if

 

[Biom]

Any gold powder after precipate should be cleaned and washed very truly.you may have drag down if you use extra precipetan but it's not a problem as long as you clean it and some pinch sodium nitrate some sodium bicarbonate as a flux .so many refiners redesolve again in A R second time and use defrent precipetan .like if start with smb . Second time use ferouss solfate.because each one of them have deferent drag down .that if you talking about a lot of gold .

 

[Biom]

Use shark advice

 

[Biom]

Shark explained best way

 

[Biom]

Shark explained best way

Shark explained better .iam from Morocco .it's hard for me to explain cause of the language .

 

[Alexander_Hun]

Thanks for all the advice! The Hungarian language is also quite difficult, but I am glad to have found such a good forum where everyone is helped patiently!!
I have a question, I process the gold-plated connectors shown in the pictures above, cut them into small pieces, the nitric acid works well for a while on the copper inside... However, after a while it cannot get inside, it cannot finish the job. I tried to heat it, it gets better for a while, but there is always copper in it.... How would you do it?

 

[Biom]

What other matels you have for sure and how much in the alloy

 

[Jimbriese]

Decant off the spent acids and add fresh water and nitric until no more reaction. Then rinse well. Dissolve clean gold in Aqua Regia. Drop with your choice of precipitate.

 

[Alexander_Hun]

Decant off the spent acids and add fresh water and nitric until no more reaction. Then rinse well. Dissolve clean gold in Aqua Regia. Drop with your choice of precipitate.

Hi!

That's how I do it, but the connectors are so thin that the acid can't penetrate after a while, the gilding stays there like a frame and the acid doesn't go in, maybe because of the bubbles..