Remove other metals from gold foil

[prince]

Welcome everyone in the group.I did some reading in the group.I have some problems.I have worked with about 30 mobile boards.
I soaked the boards in HCL first And removed the solder.Then I made air bubbles in the AP solution and later I filtered the gold foil.I noticed some of the gold foils were green plastic-like material that was probably base metal.I'm adding pictures.
I want help from the veterans.How can I purify gold foils.I do group studies almost regularly and read CM Hook’s book I haven’t read yet.But refining these gold foils for my own encouragement will bring me a lot of encouragement.Thanks in advance to everyone.

 

[Yggdrasil]

Hi Prince.
I comment here based on the picture.
The green stuff looks like pieces of PCB
But as you see, the foils are covered in a grey matter, which most likely is residual tin or base metal.
wash it thoroughly in full strenght HCl and maybe run it AP again after.

How ever if you are not planning to use nitric,
you could go directly to dissolving the foils in HCl-Bleach or HCl-Peroxide.
Then drop with what ever method you like, it just needs more cleaning of the powders after.

 

[g_axelsson]

The green plastic pieces are remnants of solder mask. It will not affect the result. The gray stuff is probably tin oxides and I wouldn't worry about it either.

If it was me I would be happy with the result and go on and dissolve the gold. The trash is easily filtered off from the gold chloride.

When I do fingers I don't pour off all the foils into a filter. I let the foils settle after I have removed the circuit boards and decant the barren liquid, leaving the trash and foils in my beaker. I do filter the liquid I pour off, but the little gold I might catch isn't worth the hassle so I put the filter in my burn pile. I'll get it in the end when I process my waste filters.
The foils are then dissolved, filtered and the gold precipitated and added to my stash of gold powder that will be refined a second time in a larger batch.

Göran

 

[prince]

Thanks to you. Maybe you want to wash all the foils with HCL, then again AP method with bubble.And the AR / Bleach method is right!I have already melted similar foils.But they were all ruined. I didn't find anything.I stopped at the same place again. I hope I will get good results with the cooperation of everyone. Thanks

 

[prince]

I would have benefited more if I had received more comments. Thanks again everyone

 

[FrugalRefiner]

I can only speak for myself, but once I see someone give a correct answer, I don't make another post with the same information.

Dave

 

[Shark]

The green plastic pieces are remnants of solder mask. It will not affect the result. The gray stuff is probably tin oxides and I wouldn't worry about it either.

If it was me I would be happy with the result and go on and dissolve the gold. The trash is easily filtered off from the gold chloride.

When I do fingers I don't pour off all the foils into a filter. I let the foils settle after I have removed the circuit boards and decant the barren liquid, leaving the trash and foils in my beaker. I do filter the liquid I pour off, but the little gold I might catch isn't worth the hassle so I put the filter in my burn pile. I'll get it in the end when I process my waste filters.
The foils are then dissolved, filtered and the gold precipitated and added to my stash of gold powder that will be refined a second time in a larger batch.

Göran

This is how I do it as well. Nothing to add to it, as Dave mentioned.

 

[prince]

Sorry for the late post.I washed the gold foil shots by HCL and heated for a while.The base metals were removed and the green base metals remained.Since then I have not changed the HCL of the glass beaker.I gently added nitric to those drops and heated.
The gold foils desolved and the green base metals floated.I filtered the AR solution.I was adding a little urea but did not notice any reaction.
I was adding a little urea but did not notice any reaction.I added a few SMBs but was disappointed again.I felt very bad.I would be grateful to the members of this group for any good advice.I seek advice from experts. Thanks

 

[FrugalRefiner]

Sorry for the late post.I washed the gold foil shots by HCL and heated for a while.The base metals were removed and the green base metals remained.

I will assume that "gold foil shots" is a translation error. Gold "foils" usually come from recovering gold from plated or gold filled materials. They're called foils because they are thin flat sheets of gold or gold alloys, much like thin bits of foil you might tear off of aluminum foil in you kitchen. "Shot" is the result of melting gold, or gold alloys, and pouring into water to form what we often refer to as "cornflakes", because that is what they resemble in their form, or pouring into water under different conditions to form small, rounded beads of gold or gold alloys.

Since then I have not changed the HCL of the glass beaker.

You should have changed it. The concept of recovery is to separate the base metals from the values. You use an HCL leach to dissolve as many base metals as you can. You pour that solution off. Then you add fresh HCl and your oxidizer. That way, much of the base metal has already been separated from your values.

I gently added nitric to those drops and heated.
The gold foils desolved and the green base metals floated.

They're probably not "green base metals", but bits of the green circuits boards or the solder mask/conformal coatings that are applied to circuit boards to protect the electrical traces. After you dissolve your values, you can filter the solution to separate the gold bearing liquor from the undissolved trash. Be sure to rinse the trash into the gold bearing solution to rinse any gold bearing solution that is clinging to the trash.

I filtered the AR solution.I was adding a little urea but did not notice any reaction.
I was adding a little urea but did not notice any reaction.

Use urea in your garden. To deNO_x your solutions, use sulfamic acid.

I added a few SMBs but was disappointed again.I felt very bad.I would be grateful to the members of this group for any good advice.I seek advice from experts. Thanks

What were you expecting that you were disappointed? Did you get any gold after you added the SMB? How much? How much did you expect?

It's hard to address your concern without knowing a little more.

Dave