Yes, filter it. If any lead dropped it just became solid enough to filter it out. I usually complete the AR. When no material is left to dissolve I add the sulfamic, even if there is no nitric left. I do this just to be sure there is no lead. Then cool and filter. This removes lead and possible silver chloride at the same time.
Preparation for refinement
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Always make sure your solution is crystal clear before dropping the Gold.
Alexander_Hun
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Thanks to everyone for the answers, just so there is no misunderstanding because of the translation program:
1- dissolve gold foils in AR
2- I add sulfamic acid
3- I filter it (Here I can filter out the lead that may have precipitated from the sulfamic acid)
4- I add SMB and precipitate the gold
correct?
1- dissolve gold foils in AR
2- I add sulfamic acid
3- I filter it (Here I can filter out the lead that may have precipitated from the sulfamic acid)
4- I add SMB and precipitate the gold
correct?
That is correct, although if you are careful with the Nitric, Sulfamic might not be needed.
Add the Nitric in small increments, about one ml per gram of Gold, usually a bit less.
Heat the HCl to about 70C before adding Nitric.
Alexander_Hun
Well-known member
Thanks!
I don't dare to try it, once when I was a very beginner I lost a lot of gold. Unfortunately, I didn't know that urea or sulfamic acid was needed at the time.... After that, I tried to work with a very small amount of nitric acid, but unfortunately I didn't manage to precipitate the gold without adding anything else..
It's not a problem, that little acid at the end is really not a problem, if in return I can be calm that my gold will precipitate out.
I used to boil the gold dust in hydrochloric acid and then in distilled water, do you also do this?
Not boil but hot washes yes.
I would add here, that when you add the sulfamic, the solution should be hot. Adding sulfamic acid will deNOX the solution. Then, you should cool and dilute the solution to precipitate any silver that may be held up in the hot, chloride heavy solution. Then filter to remove both the silver and lead. That cooling and dilution are important to eliminate silver contamination of the gold.
Dave
Alexander_Hun
Well-known member
Dilution with distilled water? Can I spoil it, for example by diluting it too much?
Sorry if I'm asking a lot, but it's quite a large amount, I want to do it the best way possible.
When you're working with AR, distilled water isn't necessary. We use distilled water when working with silver solutions because the chloride ions in tap water will cause silver to precipitate as silver chloride, which we don't want. But when working with AR, the solution is already loaded with chloride ions from the HCl, so tap water is usually fine. I say usually, because not all tap water is the same. As long as your tap water isn't loaded with other metal cations, it's fine to use for the cooling and dilution of pregnant AR.
Dave
Dave
Alexander_Hun
Well-known member
One last question, when I dissolve the pins in nitric acid, can I use tap water or just distilled water?
Tnhanks!
Tnhanks!
Ideally one would use distilled, but I do not think it would matter much if there is a bit of Chlorine in the water.
What ever Gold would dissolve will cement directly out again.
Just make sure you do not pour out any powders in the solution after it is finished.
Thomas M Joseph
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If you don't have distilled water, bring your tap water to a boil for 15 minutes and leave open to air overnight. This will remove the chlorine, better but not distilled, as it will still contain other solubles.
The OP said he'd already soaked them in HCl, so the silver-tin solder would be very discolored, and as you say, depending on the percentage of silver, it'll react very differently.
These being old military-grade from the EU... I'm guess pretty high silver percentage in the solder. Be kinda pointless to gold-plate EVERYTHING to prevent corrosion, and then skimp on the solder.
Alexander_Hun
Well-known member
Alexander_Hun
Well-known member
Hello!
Today I used sulfamic acid for the first time, what is the reason that the gold precipitates in the form of a very fine powder? The addition is not very clear, unfortunately I have to refine it again. It turned out to be 14.7 grams, which is very little for 2.5 kilos, although it looked very good in front of it.
Today I used sulfamic acid for the first time, what is the reason that the gold precipitates in the form of a very fine powder? The addition is not very clear, unfortunately I have to refine it again. It turned out to be 14.7 grams, which is very little for 2.5 kilos, although it looked very good in front of it.
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What did you expect?
It precipitates as a fine powder.
Grain size may vary a bit but not much.
Alexander_Hun
Well-known member
Hello!
It's an extremely fine powder, I've never seen anything like it before. I also watch streetips videos, there is never anything like that, maybe I added too much sulfamic acid? Can I saturate the solution with it?
Muratthechemist
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- 18
Hi as i understand you are talking about the agua regia. So we use sulphuric acid to clean silverchloride from lead chloride. Means lead sulphate is liquid here. Otherwise we cannot seperate just in filtration.
If it turns liquid as lead sulphate because sulphamic acid is also sulphur kind. You should not add too much smb otherwise they will drop together.
Add sufficient amount of smb as %40 solution. You will not have any problem.
If you have a problem (you can understand of color) you can wash gold powder with diluted sulphuric acid. it will clean lead.
Wash several times with distilled water. Dry ,melt. Or direct melt slowly totaly your choice.
Alexander_Hun
Well-known member
Hello!
Yesterday I used sulfamic acid instead of urea for the first time, the solution fizzed very weakly, then when it stopped, I filtered it again.
It turned out to be such a fine gold powder that I have never seen before, its color became slightly dark. I made the mistake of not re-dissolving it in AR, I melted it and the color turned out ugly. Unfortunately, I can stand it again today, my solution is also strange, the gold precipitated out of it, there is a lighter band on top, and the color is brownish below.
I tested it, there is no more gold in it when dissolved.
I don't have sulfuric acid, can I wash the gold dust in hydrochloric acid and then in distilled water?
This is not correct Murat.
For separating Lead Chloride from Silver Chloride just wash with water.
Led chloride dissolves in water Silver Chloride don't.
Lead Sulfate will form in the presence of Sulfuric acid and it is not soluble in any acids as far as I know.
That is the reason we add a few drops of Sulfuric into our solution before filtering, so we can get rid of the Lead.
And if you have dropped the Lead before filtering SMB or other Sulfur compounds should not be an issue.
