Hello to all,
I am new on the forum but I already spent many hours reading a lot of posts ;-)
I have a concern about the precipitation of gold with aqua regia and no way to understand what I am doing wrong.
Let me explain
I started by removing the gold from the components in a mixture of 50% nitric acid at 60%+ 50% distilled water.
I made a mixture for the aqua regia of 25Ml nitric acid at 60% + 75Ml hydrochloric acid at 30% .
I dissolved my gold in it then filtered the solution which was quite yellow.
I added +- 4 or 5x the volume of distilled water and 3 spoons of urea which I dissolved well to neutralize the solution.
Then I started to add the sodium matabisulfite SMB, after the first spoon the liquid became transparent I kept on adding SMB 3 spoonfuls even 4 without success impossible to make the precipitation of gold.
Then I said to myself that maybe the neutralization was not done, so I added water and SMB again without success.
Since I'm a beginner, I do several tests and when I don't use urea and no SMB and I just add a mixture of water and iron sulphate II to the aqua regia the precipitation works.
But really wanting to understand why with urea and SMB it doesn't work I tried again but nothing to do no gold precipitate.
Finally I tried as a last resort to add iron sulfate II but this time the liquid did not turn black but orange with a sulfur smell and after 2 hours it became very clear again
Could someone tell me where I made the mistake and if it is still possible to recover the gold in the solution I have?
Thank you for reading, any help is welcome ;-) .
I added a picture to show how it look the black marks were there before, it's not the new gold.
Damocles
I am new on the forum but I already spent many hours reading a lot of posts ;-)
I have a concern about the precipitation of gold with aqua regia and no way to understand what I am doing wrong.
Let me explain
I started by removing the gold from the components in a mixture of 50% nitric acid at 60%+ 50% distilled water.
I made a mixture for the aqua regia of 25Ml nitric acid at 60% + 75Ml hydrochloric acid at 30% .
I dissolved my gold in it then filtered the solution which was quite yellow.
I added +- 4 or 5x the volume of distilled water and 3 spoons of urea which I dissolved well to neutralize the solution.
Then I started to add the sodium matabisulfite SMB, after the first spoon the liquid became transparent I kept on adding SMB 3 spoonfuls even 4 without success impossible to make the precipitation of gold.
Then I said to myself that maybe the neutralization was not done, so I added water and SMB again without success.
Since I'm a beginner, I do several tests and when I don't use urea and no SMB and I just add a mixture of water and iron sulphate II to the aqua regia the precipitation works.
But really wanting to understand why with urea and SMB it doesn't work I tried again but nothing to do no gold precipitate.
Finally I tried as a last resort to add iron sulfate II but this time the liquid did not turn black but orange with a sulfur smell and after 2 hours it became very clear again
Could someone tell me where I made the mistake and if it is still possible to recover the gold in the solution I have?
Thank you for reading, any help is welcome ;-) .
I added a picture to show how it look the black marks were there before, it's not the new gold.
Damocles