# Gold flake trapped in lye water



## markk (Nov 16, 2016)

Okay here is another one. A friend was doing fingers. Fingers pulled from AP . Flakes put in filter. There was green paint, I guess that is really called solder mask , in with it so added lye right on top of it to try and eat up the green paint. Poured water over it I think , to wash it. Flakes disappeared in filter.
Now there is a nice golden yellow solution in jar. So basically a lye/water/gold solution.

Now I assume that the gold was dissolved due to the lye and air oxidizing the gold and the acid that was still clinging to the flakes from the AP kicked in and dissolved it. ??? 
It looks just like Acid chlorox with flakes dissolved in it.
So how would one go about dropping the gold out of this solution?


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## Platdigger (Nov 16, 2016)

Simply reacidify with hcl and proceed. It will then be gold chloride.


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## markk (Nov 17, 2016)

Okay , I will tell him. Evidently it is a lot of gold in there. He was processing large amounts when that happened. Maybe I can talk him into selling it to me. Been trying to buy large amounts of scrap from him but so far no go. 
thanks


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## goldsilverpro (Nov 17, 2016)

Gold will not dissolve in lye (sodium hydroxide).


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## Platdigger (Nov 18, 2016)

GSP, if I may, let's say you have some gold in solution on the acid side.
Ok, now if you adjust the ph with sodium hydroxide until the gold comes down, now, isn't that a gold hydroxide, or gold dissolved into sodium hydroxide?
Or, is that gold that comes down in another form? Perhaps elemental?


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## butcher (Nov 18, 2016)

AuCl3 + 3 NaOH = Au(OH)3 + 3 NaCl

The gold is in the form of a hydroxide salt of gold, gold cations and hydroxide anions.
The gold chloride salt has been converted to gold hydroxide salt.
The gold hydroxide salt is insoluble in the sodium chloride salt water.


Gold will not dissolve in sodium hydroxide.
Gold will not dissolve in HCl acid.

HCl + NaOH --> NaCl + H2O


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## markk (Nov 19, 2016)

Okay so here is the challange ....Just a little fun competition.
I just tossed some LNB boards into 20% lye solution and heated to remove solder mask. I then after a while of the mask not removing, poured in quite a bit of lye. So now a hot very strong solution. 

the solution after decanting off of the green solder mask is now yellow and looks like acid clorox after dissolving gold. 

So , anyone want to take stabs at whether or not any gold is dissolved in this lye water? 
I have some stannous coming to check it . 

You would think in big Wichita,Ks I could buy a piece of tin. NOT! Had to get on ebay


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## Platdigger (Nov 19, 2016)

The color is most likely just from the dissolved solder mask.


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## g_axelsson (Nov 19, 2016)

Not finding any tin? Did you check the Ace hardware store? Looks like they have solder.
You can even use solder from a circuit board to make stannous chloride.

No gold in solution is my bet, lye doesn't dissolve gold.

Be careful, a drop of lye in the eye can blind you.

Göran


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## anachronism (Nov 19, 2016)

markk said:


> Okay so here is the challange ....Just a little fun competition.
> I just tossed some LNB boards into 20% lye solution and heated to remove solder mask.* I then after a while of the mask not removing, poured in quite a bit of lye.* So now a hot very strong solution.



You're mad. Utterly mad, especially given your lack of knowledge. There's no thought or planning going into this and you're playing with one of the most dangerous solutions you could ever play with. You need to stop this because you're an accident waiting to happen. Hot NaOH isn't fun it's extremely dangerous. It scares the bejesus out of me and I work with chemicals that others think are frightening.

My apologies to other members if they see this as harsh but there are times when bluntness is required, and this is one of them.

Edit for spelling: Too cross to type properly.


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## markk (Nov 19, 2016)

anachronism said:


> markk said:
> 
> 
> > Okay so here is the challange ....Just a little fun competition.
> ...



not to worry . I am quite aware of lye and have been using it for many years along with hcl and a few other things. Just not for PM recovery.


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## markk (Nov 19, 2016)

g_axelsson said:


> Not finding any tin? Did you check the Ace hardware store? Looks like they have solder.
> You can even use solder from a circuit board to make stannous chloride.
> 
> No gold in solution is my bet, lye doesn't dissolve gold.
> ...


I did not look for solder . just figured the cost would be far more than going to ebay and waiting a few days. I just kind of figured tin would be a common thing . Went to science education center and they had no idea why anyone would want tin powder. They used to sell stannous . Went to the yard store and thought with all the metal they sell .. nope not tin. Wichita is the place you can get anything you want as long as you have the internet to order it from. Biggest city in ks but like living in 1950 hooterville


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