Hello, As pictured below, I have several small blocks of copper with gold plating on the surfaces (and perhaps a nickel strike underneath the gold). I am confident that the base metal is copper, since it is non-magnetic and a density test produced ~ 8.7 g/ml. I searched the threads on this forum and found nothing related. Isn't it true that both the AR process and AP process will also dissolve the copper and complicate the refining?
What is the best way to recover the gold plating from a block of copper base metal
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Yes, they will both dissolve Copper, plain HCl will not though and it will dissolve the Nickel, but maybe not fast enough to avoid AP though.
If it is indeed Copper, one can use a Sulfuric stripping cell which will leave the Copper behind.
I will try one piece in plain HCL and see what happens.
Those may be brass instead of copper, but either way you can use them in your stock pot. The copper or brass will cement other precious metals from your spent solutions, and in the process liberate the gold plating.
But that's a lot of base metal to get to a little plating. The best solution would probably be cyanide, but it is NOT for the inexperienced. It rarely gives you a second chance if you make a mistake.
You may be able to make more money by selling them on eBay.
Dave
But that's a lot of base metal to get to a little plating. The best solution would probably be cyanide, but it is NOT for the inexperienced. It rarely gives you a second chance if you make a mistake.
You may be able to make more money by selling them on eBay.
Dave
Advice taken.
The best process for this type of scrap is to tumble the parts in cyanide with an oxidizer (peroxide). It will strip the gold effectively and the tumbling is important because the flat surfaces stick together and prevent solution penetration. I have stripped hundreds of pounds of these this way. The blocks were solid copper but there were no inserts installed in the blocks I stripped.
Recovery of the gold from the cyanide has been covered here before but it is straight forward and economical.
Recovery of the gold from the cyanide has been covered here before but it is straight forward and economical.
Would you like to do this for me? I am located in Mass.
Dave, you may be correct. Brass and copper have similar densities.
It's simple to check. File off a corner or edge and look at the color.
Dave
Dave
Golddigger76
Well-known member
I process these all of the time, and have some right now that I'll start soon. Cyanide would honestly be better choice if you feel comfortable using it. The gold plating is fairly thick if they came from high quality communications or testing equipment.
I'm never in a rush and the way I do it sometimes takes a month on a large batch.
I hold them one at a time with long handled needle nose pliers and beat them with a 2 lb hammer until the plating cracks in several places.
After that they go in acid peroxide until the gold plating is no longer connected, then the connectors are screened out and the gold goes into AR.
These are usually made of brass.
I'm never in a rush and the way I do it sometimes takes a month on a large batch.
I hold them one at a time with long handled needle nose pliers and beat them with a 2 lb hammer until the plating cracks in several places.
After that they go in acid peroxide until the gold plating is no longer connected, then the connectors are screened out and the gold goes into AR.
These are usually made of brass.
Thanks Golddigger76. I am not comfortable using cyanide at this point in my life. I am just a beginner and I only feel comfortable using AP (Copper Chloride etch/leach) and AR. I filed the corner of one of these items (per FrugalRefiner's suggestion) and it appears to be copper and not brass. These are high quality, industrial telecom parts made in the late 80's and early 90's I have quite a few of these in my possession and looking for refining options. Thanks guys.
Question : .....when they go into the AP solution, doesn't the copper base metal begin to dissolve and create a problem (assuming that you don't use excess hydrogen peroxide)? Or, does the gold just flake-off like fingers from a circuit board?
The first that go into solution is the Nickel plating.
And then the plating is loose.
It might be better to just use plain HCl, it will in time turn into Copper Chloride and start leaching the Copper. But by then the Nickel plating should be gone.
Edit for spelling
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I remember that you stated that on Monday - I like that simple idea and I will perform a test tomorrow. I am assuming that there is a nickel strike below the gold plating.
Golddigger76's idea of pounding the item with a hammer is interesting... Wouldn't it create cracks in the plating that would assist in the leaching? I may try two samples in HCL, one "as-is" and one "hammered". If the hammered method works better, I'll need to enlist ten neighborhood kids with hammers, to help me. What could possibly go wrong there?
Golddigger76's idea of pounding the item with a hammer is interesting... Wouldn't it create cracks in the plating that would assist in the leaching? I may try two samples in HCL, one "as-is" and one "hammered". If the hammered method works better, I'll need to enlist ten neighborhood kids with hammers, to help me. What could possibly go wrong there?
If the plating is thick, there will be no reaction or at least negligible, due to the acid is denied access to what it can react with.
Ohiogoldfever
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Makes good sense to me. I often cut older style fully plated connectors in half to speed up AP. I’m never in a hurry really but I’ve had thicker plated stuff lay in AP for weeks with no reaction.
Open up the base metals to allow the acid to work past the gold faster.
Ohiogoldfever
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I guess I want to know where I can get some of these boxes…
Golddigger76
Well-known member
Breaking the plating is the reason for hammering them.
It gives access for the acid to react with the base metals.
The first time I tried to strip off the gold plating by letting them soak whole without cracking the gold in hydrochloric/peroxide with a couple pounds of gold plated pins.
They were in the acid for a few months and they looked just how they did when I put them in.
I used my bench grinder to expose the brass and could see how thick the gold plating was.
Then I tried the hammer trick, back into the acid and it finally started working.
The base metals are too much to completely dissolve in a reasonable time but the plating with completely release.
This method still takes a long time, and that's why I believe cyanide would be faster and would still be cost effective way to remove the gold.
It gives access for the acid to react with the base metals.
The first time I tried to strip off the gold plating by letting them soak whole without cracking the gold in hydrochloric/peroxide with a couple pounds of gold plated pins.
They were in the acid for a few months and they looked just how they did when I put them in.
I used my bench grinder to expose the brass and could see how thick the gold plating was.
Then I tried the hammer trick, back into the acid and it finally started working.
The base metals are too much to completely dissolve in a reasonable time but the plating with completely release.
This method still takes a long time, and that's why I believe cyanide would be faster and would still be cost effective way to remove the gold.
Thanks guys. I am going to run two tests with plain HCL (as Yggdrasil suggested) to determine if it can dissolve the nickel strike that I assume is underneath the gold. I think the plating is fairly thick, as these items came from high-end, industrial grade electronics built in the 80s and early 90s. I'll keep you posted....
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I had some high-grade contacts from that era that had no nickel. It was gold plated directly on the copper. No choice but to dissolve them completely to recover the foils, since I don't yet have the setup for a sulfuric stripping cell. But, I did as others have suggested use them in the stock pots to cement any PMs in solution. Then I filter the foils along with the PM powders at the bottom of the stock pot.
