500 old cellphones, what's best process?

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R

recycledokter

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Oct 21, 2015
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4
I have around 500 old cellphones, what process do you think I can do best to recover and refine the gold myself?
I did two tests batches of 25 boards.
First take of all components with heatgun.
And I used air bubble system with only HCL.
Now I have the gold in my filters, I will refine later.
But is this the best way to get the gold?
I think the saffest, because cannot lose gold in the solution,right?
 
You didn't mention how you started your leach solution. It sounds like you didn't add any hydrogen peroxide as an oxidizer, and that does avoid the problem many people experience when they add too much and dissolve some of their gold at the beginning. The air will oxidize the copper to get it going, it just takes longer.

I won't agree with your last statement
I think the saffest, because cannot lose gold in the solution,right?
Click to expand...
There are many ways to lose gold, even with the CuCl2 method. Just as air will oxidize the copper, it can also oxidize gold. Left for long enough, under the right conditions, some of your gold can dissolve. If you use the leach long enough, copper will continue to dissolve and cement the gold back out of solution as a fine powder. So if you discard the powder, you can lose gold. In a small batch, you could have some gold in solution. If you discard the solution, you can lose some gold.

You can lose gold in any process. Test as you go so you know where your gold is.

Dave
 
Thanks Dave for you reply.
I did not use hydrogen peroxide.
And you are right for sure with testing, here in the Netherlands it's hard to find pure tin.
But I know I really need this to always test my solution.

Keep on mining bro! 8)
 
Any tin works to make stannous, it doesn't have to be pure. You can even dissolve some from your cellular phones.
If purity of the tin was an issue then we wouldn't be able to test dirty solutions.

I make mine stannous from an old pewter bowl, it will last for the rest of my life.

Göran
 
I guess that if you get the oxidation potential high enough to dissolve gold then the tin has already been oxidized into metastannic acid or other tin oxides / hydroxides?
...or will it form a gold colloid on the fly?

Göran
 
I think both are possible and to consider. So, you guys are right, if he waits to long and the oxidation potential gets high enough, gold dissolution gets possible and can be detected with fresh stannous.
 
Reading butcher I've learned it will form colloidal gold that will not settle and impossible to test with stannous. This is why tin should never get to where gold could be dissolved, eg AP.
 
Thanks guys for the replies.
I know do batches of 20 phones, and work on my gold recovery and keep the gold on my filters for now.
Also I now just keep the gold pins and connectors in a pot.
I will keep you posted if I get any further.

Keep on mining! 8)
 
I put a bunch of the flexible brownish circuit things from cell phones in fresh cucl2 and left it in there for quite a long time. There was quite a bit of exposed gold showing as well as some solder. Filtered everything through a double or triple filter paper and was surprised at how little the amount of gold foils was. I was wondering if it could have somehow been dissolved by the cucl2. I thought that maybe it had cemented back out onto the exposed copper. Tested the cucl2 solution with known good stannous, but it showed negative for gold. Any ideas on where the gold may have gone to, or what might be the best way to recover it? I still have the used cucl2 solution which was made from several gallons of HCl and a splash of H2O2.

Previously when using cucl2, I have only processed boards or finger contacts which had no solder (or anything else) on them and everything worked out exactly as expected.
 
When I process cell phone boards I do it this way.

1. Depopulate with heat.
2. Soak in HCL to remove the tin. Rinse well.
3. Dissolve the copper from the now tin free boards to release the gold foils in CuCl2. (Start the process with a small amount of peroxide, keep running with a bubbler.)

Works quite well, the pre-soak in HCl will keep the CuCl2 from building up dissolved tin and the potential of dissolving gold.

Edit to correct some spelling.
 
bswartzwelder said:
I put a bunch of the flexible brownish circuit things from cell phones in fresh cucl2 and left it in there for quite a long time. There was quite a bit of exposed gold showing as well as some solder. Filtered everything through a double or triple filter paper and was surprised at how little the amount of gold foils was. I was wondering if it could have somehow been dissolved by the cucl2. I thought that maybe it had cemented back out onto the exposed copper. Tested the cucl2 solution with known good stannous, but it showed negative for gold. Any ideas on where the gold may have gone to, or what might be the best way to recover it? I still have the used cucl2 solution which was made from several gallons of HCl and a splash of H2O2.

According to MarcoP's post "if" you have dissolved/colloidal gold in your solution with that dissolved tin it's won't show up in a stannous test. And if you have metastatic acid, from what I've read it's really hard to get the gold back out. Luckily with only a 20 board batch, you haven't lost much gold.
Click to expand...
Click to expand...
 
The plating on the flex boards could be so thin that the foils breaks up and is hard to see even if the gold is there.

Göran
 
Basically until it stops fizzing and bubbling.

Once that has stopped you've removed the vast majority of it. HCl loaded with tin smells quite yicky too....
 
A large majority of the flex boards were the ones underneath the pushbuttons. Since they get a lot of use when dialing/texting, I would have thought the gold plating would have been thicker. I'll use pure HCl without the peroxide to get rid of any solder in the future and keep a watch on it. I guess I'll just write off this first batch as a loss. Thanks.
 
bswartzwelder said:
I guess I'll just write off this first batch as a loss. Thanks.
Click to expand...

It's never a loss unless you actually throw it away. There's always another way to fix it.

Edit - Couldn't he just evaporate the solution, incinerate the powder, then put it into fresh HCL to remove the tin?
 
spaceships said:
Basically until it stops fizzing and bubbling.

Once that has stopped you've removed the vast majority of it. HCl loaded with tin smells quite yicky too....
Click to expand...

Yes, you can see the reaction slow down and finally stop. Where the tin was will be a black/grayish color.
 

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