Nitric Acid + goldPins = gold + white grease

[Mice]

Hello Comrades!!!


Fast question.
I've tried do some recovering from gold pins(test of 12g).
Clean stuff. no tin.
Nitric acid 65% pure.


Photo one:
Stuff to proceed:


After while brown fumes comes up. Standard operation...

And after filtrating....




What i did wrong?
And how to dissolve this white thing to clear fakes...

Thx for all!

 

[g_axelsson]

Fast answer,

I think you have tin, many alloys contains tin.

Göran

 

[Harold_V]

I agree. It may be tin, but even if it isn't, there's a universal method for processing such material--one that yields great benefits, and is generally ignored by most of the guys on this board.

Can you say incineration?

Incinerate the solids, including the filter--then digest the remains in hot HCl. Rinse, allow the solids to settle, then decant (siphon off the rinse water), then dissolve the values with the solvent of your choice. I used AR. Filter, and the remaining unwanted solids will be left behind in the filter. Rinse the filter until all yellow is gone, so you don't lose values to the filter paper. Tap water is adequate.

The hot HCl wash after incineration will provide one service that is invaluable. The solution that comes from the dissolution of values will filter easily. That isn't always the case if you don't do the HCl wash.

Harold

 

[Mice]

Incineration sounds great.
But what i have on my filter its really small amount of Au. I don't want to make Au flakes go away
I am studying way with NaOH.

I am going to try it tomorrow.

Post the results here

Thx for fast response!

 

[Harold_V]

You must use care, as the gold foils are easy to lose---but the end result is excellent.

Make it a habit to use the same pan for incineration, then, when it has outlived its useful life, it can be placed in the stock pot (even if it's stainless) where it will slowly be dissolved, so any values that were contained within will be recovered in due time. I do not recommend a steel pan, as it is destroyed quickly---and aluminum will melt if you incinerate as you should.

Harold

 

[Mice]

Ok. I maked NaOH hot wash but works not so well. Incineration works well

Since i recovered gold (+-8g) i wash it with hot water, hcl, water, hcl. All comes together just fine.

After all, i add hcl just enough to cover golden flakes. Then drop by drop i started with CL (ACE=Clorox).

After all gold goes to the solution i wanted to make it down with diluted copperas + little HCl
And here is something that i can't understand.

First photo:

Some of gold is down but way to less than i expected (maybe chlorine gas is still there..)
Adding more of copperas give nothing so I stopped working with this guy.


Another photos.


I don't have tin salt to make a test for gold so i decided to make it.

I dissolved a tin wire SN+PB (solder wire) in warm HCl.
After mixing two drops of mixtures i have no sing of gold in solution....way to far for me now





I understand that chlorine gas make the drop impossible to happen. Should i wait or there is another solution?
Help

 

[jeneje]

Mice, gold will dissolve in NaOH, if you plan on using NaOH please research the health hazards, NaOH fumes can effect your health months down the road. Be careful and wear protective clothing.
Ken

 

[Smack]

You used solder with lead in it?

 

[Mice]

Mice, gold will dissolve in NaOH, if you plan on using NaOH please research the health hazards, NaOH fumes can effect your health months down the road. Be careful and wear protective clothing.
Ken

Yes, my first test batch(12g). After treating pins with HNO3.
Recovered by burning white solution to the carbon
I'am familiar with hazard of condensed and hot NaOH, safety equipment on first place Guys!

Rest of, was in A/P then washed with hcl/water until no color change was observed.

After dissolving in hlc-cl i have drop issue.

You used solder with lead in it?

Standard solder for electronics. So, yes is containing Pb also.

 

[butcher]

You need a (Known gold standard test solution) to test your stannous chloride.

Although most of the lead would form a precipitant of lead chloride, I do not think I would trust stannous chloride made with lead solder.

Try to find a more pure tin solder or tin source.

If too much chlorine the stannous chloride test will not reduce gold, you could take a small sample of the solution and heat it to drive off chlorine gas (if any is in solution) and retest it.

You state you had ferrous sulfate (copperas), Hoke's describes how to use a white spoon (or spot plate) and a few drops of solution to be tested, adding a crystal or two of ferrous sulfate, a brown ring of precipitated gold will form if gold is in solution.

Harold has also posted some very good posts on using ferrous sulfate in testing solution's

Understanding these tests are worth their weight in gold, studying them will pay you back in gold, practicing the experiments in Hokes book.

Using what she teaches, you to do some of your own experiments which can be very helpful.

Say I wanted to see how a tiny bit of chlorine would affect a test, I could do a small experiment.

I could take a small sample of the known standard gold solution, and do a test with my homemade stannous chloride , a positive violet color would prove my stannous chloride was working, now I could take another sample of the gold solution and add a drop of chlorine (sodium hypochlorite) and retest it, the negative test would prove the chlorine would not give a positive reaction (with gold known to be there, going further I could heat the sample drive off chlorine and retest...

With these small experiments use you imagination, to come up with your own test to learn more here is one I tried:

I had a gold solution on a q-tip which I added stannous chloride, I got a violet reaction, By holding this same Q-tip, in the fumes of another solution I was evaporating off the nitric from aqua regia, the positive reaction (violet disappeared) this showed me two things, that nitric was still coming off of the aqua regia solution as NOx fumes, and that the nitric formed on the Q-tip would redissolve, the violet colloidal gold, in the stannous test.

 

[goldsilverpro]

Mice, gold will dissolve in NaOH, if you plan on using NaOH please research the health hazards, NaOH fumes can effect your health months down the road. Be careful and wear protective clothing.
Ken

Gold will dissolve in NaOH???????

 

[niteliteone]

Mice, gold will dissolve in NaOH, if you plan on using NaOH please research the health hazards, NaOH fumes can effect your health months down the road. Be careful and wear protective clothing.
Ken

Gold will dissolve in NaOH???????

I don't know about "dissolve" gold, but I have watched it remove thinly plated gold from electronics, leaving clean base metals behind.

 

[butcher]

Elemental gold metal will not dissolve in NaOH.
No matter how fine the gold is, even our precipitated brown gold powder would not dissolve in NaOH.

If the thin gold came off of the base metals it did not dissolve off, it was undermined and fell off, or fell apart as gold powders or fine foils.

There are several metals that are Amphoteric, gold being one of them, these metals as ions in a solution can be precipitated as oxide or hydroxides from solution using a base (alkali) like NaOH, and if excess NaOH is added these metal oxide/hydroxides will redissolve back into solution.

 

[Harold_V]

Mice, gold will dissolve in NaOH, if you plan on using NaOH please research the health hazards, NaOH fumes can effect your health months down the road. Be careful and wear protective clothing.
Ken

Gold will dissolve in NaOH???????

This from the guy who thinks he can advise readers of his own forum?

He's bound to be successful. Don't know how he can miss!

Who better to lead the masses than one who can not see?

Harold

 

[Mice]

Ok. I have done this batch with success!

Batch was contaminated with iron. This is solving color issue. Pb in soldering tin was a problem in tests... i used sn/ag alloy to make test solution. It Work's.

I had to wait one day and warm up solution to evaporate chlorine gas and then add copperas to solution.
Rest of gold went down.
Solution remain yellow still, but after test there was no gold in it.

Thanks for all good advices. And yes, Hoke's wins!