# Cell with HCL to strip circuit boards. How to get the gold?



## NobleMetalsRecovery (Mar 3, 2008)

I used a cell with HCL to strip some circuit boards that had small gold plated IC's attached. The HCL cleaned most everything off the boards. The liquid is now black/yellow. What I mean is that it's black if you look into it, but in a white plastic bucket a thin film of the liquid is bright yellow. It tests Negative for gold. I figure the gold must be in the suspended black particles and the dark grit that's left on the bottom. 

Also, I'm including some pics showing where some copper and some gold plated onto the glass tube used as a cell.

Any ideas on how to track down the gold, and any Pd, or Ag?


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## NobleMetalsRecovery (Mar 3, 2008)

Take a look at this picture. It looks like some of the gold has plated to the circuit board?


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## skyline27 (Mar 3, 2008)

I'm not exactly sure what type of boards you used but wouldn't you be better off removing the gold laden portions to avoid all contaminants?


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## NobleMetalsRecovery (Mar 3, 2008)

This was done as an experiment as a way to remove the chips from the board. They were small gold top ceramic IC's. Each board has a few dozen of them. 

As usual, the gold was in the bottom in all the debris. I put AR over the pieces of circuit board and the other junk on the bottom, the AR is now testing positive for gold.


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## lazersteve (Mar 3, 2008)

Steve,

I've been following your experiments with the HCl column and it seems like everything always comes out in a sludge at the bottom. 

When Dallas first posted the HCl column one of the questions I asked him was about sludges and he replied that there were none formed. He said the copper plated out at the top and that was it.

I think you are definitely making progress, but I'm hesitant to adopt the technology until the gold purity from the device is better. It seems as though some of your experiments show gold goes into the solution and with other experiments the gold remains solid. Does it seem to have something to do with the amount of base metals dissolved along with the gold?

It looks very well suited for cpus and quick stripping circuit boards.

Steve


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## NobleMetalsRecovery (Mar 4, 2008)

Thanks for the input. It's good to know you're keeping an eye on it. I've done a good bit more, Will update later. i see the beginnings of a system here. i like the way it strip boards, and makes the pins fall out of connectors.


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## NobleMetalsRecovery (Mar 4, 2008)

Here's an example of how you could do the cell using two different containers. One is used to dissolve the metals the other will collect them. This keeps the two separated and keeps the chlorine gas out of the receiver. The CPVC plastic tubes form a liquid connection between the two containers.

There's a little bit of a trick to filling the connecting tube, but it's not too complicated.


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## NobleMetalsRecovery (Mar 4, 2008)

Here's my thinking on the twin cells. Fill each cell and the connecting bridge with HCL. Place carbon rod electrodes or similar conductors in each cell. Perhaps carbon in one, and SS in the other. Add gold bearing material to one cell, hook up the anode (positive) wire. This will produce chlorine gas in that cell, and the other cell with produce hydrogen gas. 

Chlorine gas in HCL will dissolve gold. So everything (except lead and silver) will dissolve in the anode cell. The cathode (negative) cell will not have chlorine gas so I think the base metals plating over to the cathode cell will dissolve in the HCL to form chlorides, but the gold should not re-dissolve because of a lack of free chlorine. Will test out the theory soon.


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## NobleMetalsRecovery (Mar 4, 2008)

The pictures do not show that the connecting bridge has the two open ends that are submerged in the liquid turned upwards. This is to prevent the gases forming in each cell from entering the bridge tube and breaking the continuity of the solution.


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## NobleMetalsRecovery (Mar 5, 2008)

Both cells are filled with HCL, and the connecting bridge is also filled with HCL. A 12 volt battery charger is hooked up to a graphite rod at the anode and a stainless steel rod at the cathode. Bubbles are forming on both of the rods, but the amount of bubbles is tiny. 

It looks like it would take a month to do anything at this rate. Wonder if I should raise the voltage? I seem to remember reading once that copper refining cells take about a month to cycle.


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## NobleMetalsRecovery (Mar 5, 2008)

Higher voltage didn't help, but things are going better now that I've added some metal for the acid to work on.


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## banjags (Mar 5, 2008)

This looks very interesting. So if I understand correctly. In the last picture with the gold fingers on the right side The gold will be dissolved in that jar and stay in that jar, and the base metals will migrate to the jar on the left?
Why is the anode inside of the plastic pipe?
Where did you get those jars?
How does the pipe connecting the 2 jars stay filled and how did you fill it?


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## NobleMetalsRecovery (Mar 5, 2008)

Everything should dissolve in the jar on the right side, gold and base metals. Then all the metals should migrate through the bridge to the cathode. I'm thinking the base metals will dissolve in the HCL, and the gold will just accumulate on the stainless steel rod. 

The jars were on eBay, Bellco jars. I may have a few extras to sell, contact me by PM. 

The tube stays filled based on the principal of a siphon. The liquid trying to leave the tube creates a vacuum and stays in the tube. Filling the tube was another trick. I added 6" extension tubes on each end. I then filled the tube with a small funnel. Then I capped the end of one of the extension tubes. Now with the connector joint where it meets the extension tube being below the HCL liquid level I unscrewed the one extension tube without the cap. The liquid in the bridge could not drain because one end was under the HCL liquid level and the other end was capped. I then removed the second extension tube with the connector joint where it meets the extension tube being below the HCL liquid level. This way air was excluded at all times from entering the bridge tube. Also, the bridge tube has the ends turned upward in the HCL so gas bubbles forming do not enter the bridge tube and break the liquid pathway.

Maybe I'll get to add pics of the tube filling procedure later.


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## NobleMetalsRecovery (Mar 5, 2008)

The reason I forced the carbon rod in the tight fitting plastic pipe was to make the electrode establish electrical contact lower down in the jar to evenly distribute the chlorine gas being formed. This keeps the gas formation away from the surface where it would just escape into the air. It is needed to be dissolved in the HCL to dissolve the gold.


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## banjags (Mar 5, 2008)

Does it matter what the anode and cathodes are made from? Do they need to be Carbon and SS? Could the both be SS? or some other metal that will not dissolve in HCL


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## NobleMetalsRecovery (Mar 5, 2008)

The anode matters the most because chlorine gas is formed there. Carbon or graphite are the best choices. The cathode is less fussy, that's where the metals accumilate, but remember it's in HCL, so you want something that can handle the HCL. 316 SS is better than regular SS. Also, Monel, Inconel, maybe Titanium, etc.

We need to see how this thing works. If it just plates out the gold, then a gold cathode would be great.


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## Andrew W (Mar 12, 2008)

Very interesting apparatus! Any updates?


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