Hey, where did my gold go?

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C

creading

Member
Joined
Jun 29, 2009
Messages
14
I watched Steve's videos and took notes. I processed 540 g of fingers with AP and they turned out beautiful.
I dissolved they in AC and everything went according to plan.
I filtered and diluted to 1 quart, and let sit overnight. No smell of chlorine in the morning.
I added 375 mL of filtered saturated SMB with stirring, and the solution went clear. I waited with anticipation for the brown to appear................................................
I added more SMB..................
more................. Hey, where did my gold go?

Prospector
 
You don't mention any testing with stannous chloride. Did you test? Did you get an indication of gold before you tried to precipitate? Did you test after trying to precipitate? Sometimes you can't count on adding set volumes of chemical to get the desired effect. Since the gold in solution isn't visible it's easy to see the value of stannous chloride testing.
 
4metals is spot on! I would not wish to refine gold without stannous chloride on hand.

If you do not have any, you may find a mild heating (about the temp of coffee) will cause your gold to precipitate at the point you apparently have your solution. Even if this works I would discard nothing until you have tested it with stannous.
 
I'm pretty sure it is in solution. There was over 7 grams of clean gold fingers that dissolved in the AC. The fiolter only had a small amount of fiberglass circuit board fragments. This solution was only diluted with water prior to the addition of SMB. I'm not sure how well stannous chloride works in high concentrations of SMB.

Prospector

P.S. Hey, where did my gold go?

Whilst I was replying, Oz replied

Thanks, I'm heating it now to test this idea. It would seem that it was so clean as to lack nucleation. If I added a tiny amount of gold precipitate from a past isolation, this should probably nucleate the precipitation, if that is the problem.
 
Nucleation is not your problem here, and I doubt that a lack of nucleation sites would stop the reaction. Even if it could you can be sure your solution is not filtered that well unless you are using some very special equipment.

Speaking of filtration, you mentioned that you filtered before dilution but not after. Typically one dilutes gold chloride to precipitate out traces of silver and also a little bit of sulfuric to precipitate out lead sulfate, then you decant or filter so you do not include your precipitated silver chloride and lead sulfate in with your precipitated gold. This is particularly important with electronic scrap.

I have found that during the winter since I work in an unheated space that a bit of heat helps if it is a dilute gold chloride. Concentrated solutions provide their own heat as gold chloride and sodium Metabisulfite is an exothermic reaction. Warming or even boiling briefly an HCl-Cl2 solution is always a good idea before your SMB as it will drive off any free chlorine that may still have been in solution. If it does not work let it set overnight, you may have a surprise in the morning. Let us know your results.
 
Thanks again, Oz. I'll let you know of any surprize in the morning. And thanks for the info on a little sulfuric. There were no traces of silver precipitate upon dilution, and the solution remained that beautiful deep yellow color prior to SMB.

Prospector
 
i know exactly how you feel, i took 39.1 grams of pins (very clean) placed in muracic acid and h-peroxide let set overnight, inspected with magnifying glass to check for any gold left on the pins, 1-10 had a small trace of gold.
removed the pins and dried, weighed pins again being 27.1 grams fixed a smb solutin to drop with (do not need to treat with urea with this combo) mixed in the smb weighted 4 hours or more very slight amount of gold in bottom of container, no mud, maby a verry small trace amount of a sand. tested for gold in soulution, it is there i cannot get it, i have had problems dropping gold every time. what to do!!!!!!!!
 
I have noticed that when I do the CPU heavy gold plated pin sockets, some of the gold does go into solution with the AP, but when the copper gets to a good color, the gold precipitates out, and can be filtered after letting the pins settle. Every time additional peroxide is added, the color changes, the precipitate clears, and then as the peroxide is exhausted, the copper precipitates the gold once again. I now wait until I can see the gold microcrystals as the peroxide is exhausted, stir vigerously, and filter the solution. I then add additional peroxide and dissolve some more gold. The gold in the filter is golden color, not brown like a SMB precipitate. Most of the copper of the socket remains intact, rather than dissolving in the AP.

Prospector
 
huelo said:
i know exactly how you feel, i took 39.1 grams of pins (very clean) placed in muracic acid and h-peroxide let set overnight, inspected with magnifying glass to check for any gold left on the pins, 1-10 had a small trace of gold.
removed the pins and dried, weighed pins again being 27.1 grams fixed a smb solutin to drop with (do not need to treat with urea with this combo) mixed in the smb weighted 4 hours or more very slight amount of gold in bottom of container, no mud, maby a verry small trace amount of a sand. tested for gold in soulution, it is there i cannot get it, i have had problems dropping gold every time. what to do!!!!!!!!
Click to expand...



Hello,

Depends what type of pins you dissolved, some type of pins have a yield just only 0,5%-1%, meaning between 5 grams-10 grams/1kilo of pins,...or in your case-from 39,1 grams of pins- you can expect just 195mg-391mg of gold.Therefore, a fifth part of a gram of brown mud can be little even under the magnifying glass.

teclu
 
I awaited the prescribed period, then I went out to look at my pot of dissapearing gold.

Just as Oz predicted, the leprechauns had returned it to the bottom of the beaker, as a beautiful golden powder.

And I thought this was science!

Prospector
 
Chances are that you had Cl2 gas still in your dilute gold chloride. Free chlorine will cause you to need an excess of SMB and hinder your reaction. In the future it is best to give your gold chloride a short boil if you made it with HCl Cl2 before you try to precipitate. The Cl2 is driven off easily with heat.

Now buy or make some stannous chloride and test your solution before sending it to the stock pot.
 

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