Gold Cell - Pins turn copper plated?

[poet]

Just a quick question about the pins and other misc gold plated items I have been testing out in my gold cell (con sulfuric, lead, copper basket, dc power supply). After the gold appears to be removed from the objects, a copper plating starts to form on said items. Is this the norm?

I could not find the answer via searching the forum or any of the literature I've downloaded from here. Hopefully I didn't overlook the answer.

 

[lazersteve]

Got any photos?

Sounds strange to me.

Steve

 

[poet]

This has happened to most everything I've tested in the cell except for a few bronze/brass base metal items.

Got any photos?

When I get home later I'll upload a picture of the RF connectors I was testing out earlier.

 

[nickvc]

Poet you have the expert helping already 8)
Just a few thoughts..are you using concentrated sulphuric in your cell?
Is the copper coating appearing or been exposed by the action of the cell?
Is there powder in the bottom of the cell after settling?
If this is your first attempt at recovery or refining it all seems a bit strange at first but keep reading and it will make sense eventually.

 

[poet]

Just an example of whats happening in the cell and what the original items looked like.

 

[nickvc]

Poet to me it looks like the cell has done it's work and stripped your gold plate off.
Take a small file to one of your items and expose the base metal, i suspect that what you will find is copper. Also watch the reaction in your cell, does the gold colour disappear leaving that copper exposed? If the answer is yes then the cell has done it's job and your gold is the black powder in the bottom of your cell or floating around in it.
The cell works by creating persulphuric acid around the anode which dissolves your gold and as it moves away from the anode it becomes sulphuric acid again which causes your gold to precipitate out as that black powder. Clever stuff and developed into a useable process by our very own Lazersteve.

 

[poet]

Just a few thoughts..are you using concentrated sulphuric in your cell?

Yes. I bought 5 gallons of battery acid from NAPA and boiled off the H2O.

Is the copper coating appearing or been exposed by the action of the cell?

I have no reason to believe there is any copper in these rf connectors. Most of the ones I've chopped in half are bronze/brass with a gold plating.

Is there powder in the bottom of the cell after settling?

If powder you mean the black gold/sediment/trash/etc, yes. I've done 5-6 lbs of these and have washed/refined the sediment.

If this is your first attempt at recovery or refining it all seems a bit strange at first but keep reading and it will make sense eventually.

Close enough to first attempt. I'm just taking the entire process at a snails pace whilst I absorb the knowledge from this forum and it's wiser-than-I members. I've had no issues so far with my cell or washing/refining processes. Just curious about the copper plating that forms as I have yet to see anything similar in all of the videos I've watched.

Just to be clear on my process up to the point where the copper plating forms:

- Fill pyrex container with a few cups of concentrated sulfuric acid.
- Added lead (formed from fishing weights) cathode on one side of container.
- Added copper mesh anode on the opposite side of the container.
- Added plated items on top of copper mesh, ensuring they are covered by the sulfuric acid.
- Connected the negative terminal from the DC power supply to the cathode. This PS is 15VDC/15A max output.
- Connected the positive terminal from the DC power supply to the anode. This PS is 15VDC/15A max output.
- Turned on DC power supply.
- Observed the cell work its magic.

 

[nickvc]

Seems you have the process right and are doing everything you should be but as I said Steves the expert here.
Make sure you keep your cell covered when not in use as concentrated sulphuric is very water hungry and will absorb water from the atmosphere very readily, this came from Steve and Oz and I'm ready to believe anything either of them tell me.
Does that copper colour become apparent as you take the items out of the cell or after you have rinsed them? I'm asking because I've noticed over the years that weak sulphuric as used in jewellers pickle will leave a copper colour on silver put in there, i dont understand the chemistry but it happens, the other thought is that your sulphuric is loosing it's concentration by absorbing water allowing it to attack the copper mesh or the copper in your items which then coats your items as in the observation above.
I'm sure Steve will have the answers to all your questions and can explain much better than me so if your still unsure await his replies.

 

[poet]

The acid is new, and I make a point of not diluting it by; covering the container up when not in use, drying off anything I rinse and put back in the cell.

It's getting the copper plating/coloring while the cell is on.

 

[Harold_V]

Just a quick question about the pins and other misc gold plated items I have been testing out in my gold cell (con sulfuric, lead, copper basket, dc power supply). After the gold appears to be removed from the objects, a copper plating starts to form on said items. Is this the norm?

I'm of the opinion that you aren't seeing copper plating, but copper that is exposed as the alloying agent (zinc) is removed. The action will ultimately cease as the exposed zinc is dissolved.

From your pictures, I'd say you're doing a very nice job of stripping.

Harold

 

[dtectr]

I'll second Harold's observation - the base metal is usually flash-plated with copper which is more conductive in order to apply the considerably thicker underplating, usually nickel. You're probably leaving your components in longer than you need to & nickel is being stripped, revealing the copper base coat.

Here's one I found to be counterintuitive - the shinier your gold finish, the thinner the gold plating. The shine of the thicker nickel coating actually shows through the thinner gold coat. Since gold in its native state is dull, taking a shine only after polishing, therefore, duller gold = more gold.

 

[poet]

I probably am leaving the items in longer than necessary.

Thanks everyone for your expert opinion.

 

[eeTHr]

nickvc---

If I remember correctly, the red color on pickled silver comes from iron. Copper tongs are used for putting silver into and removing it from the pickle.

 

[EDI Refining]

Are you using copper mesh in your unit ?

 

[qst42know]

To test for copper in solution you could dip a clean iron nail and see if it doesn't come out copper clad.

 

[poet]

Are you using copper mesh in your unit ?

- Added copper mesh anode on the opposite side of the container.

 

[EDI Refining]

ok. When the solution is running hot, my guess is part of your mesh is going to the parts after the au is stripped.

 

[golddigger2]

I have also noted this happening. I put the deplated items into a bucket of water after removal from the cell, so that any gold mud can be washed off the depleted pins. I believe there is enough dissolved copper in the mud and sulphuric to allow it to plate back out on to the nickel of the rubbish pins giving them an extremely thin copper coating but it has never happened in the cell itself. If the acid is not 95% or is allowed to get hot as I'm sure steve has already pointed out you will end up with a significant amount of copper dissolving in to solution from the copper basket. 2 things to remember when using a copper basket in a cell. Use laboratory grade 95% sulphuric and do not let the acid get hot!