WeirdoC
New member
I had a bottle of HCl-Cl solution that I had used to strip the gold plating off of plate rims a few months ago. Knowing that there would only be a tiny bit of AuCl3 present, and that it wouldn't be worth it to drop the gold with SMB, I bottled it up and put it on the shelf with the intention of waiting for a batch of finger foils to add to it.
I paid a few dollars for a necklace that had a miniature reproduction of a gold Krugerrand on it, which the guy told me was a 24K gold medallion on a 14K gold-filled chain. Thinking, "Hey, if it's 24K, I can just drop it in my HCl-Cl and it'll eventually dissolve and I can precipitate it out with the rest of my gold," I went ahead and removed the medallion from the chain. I was going to cut it into smaller pieces with a pair of diagonal cutters to hopefully make it dissolve faster. My first big hint that it wasn't 24K should have been that it was pretty hard to cut, despite being very small... But I just figured my cheap cutters were dull as all get out, so with a heavy groove running down the middle of the coin where I was meaning to cut it, I threw it into the bottle of HCl-Cl.
Oops. Pretty soon, I had a very thin, very hollow, gold-colored shell sitting in the bottom of a bottle of HCl-Cl that now had a much more distinct green to it. The gold foil did dissolve eventually as well, but now I have unknown contaminants in my solution, though it seems likely that copper is among them. If I had to guess, I'd say it was probably gold plating on a brass coin, which means copper and zinc in my solution.
After perusing the forum looking for the remedy, I think I know what to do, but I'd like to verify with the experts:
I paid a few dollars for a necklace that had a miniature reproduction of a gold Krugerrand on it, which the guy told me was a 24K gold medallion on a 14K gold-filled chain. Thinking, "Hey, if it's 24K, I can just drop it in my HCl-Cl and it'll eventually dissolve and I can precipitate it out with the rest of my gold," I went ahead and removed the medallion from the chain. I was going to cut it into smaller pieces with a pair of diagonal cutters to hopefully make it dissolve faster. My first big hint that it wasn't 24K should have been that it was pretty hard to cut, despite being very small... But I just figured my cheap cutters were dull as all get out, so with a heavy groove running down the middle of the coin where I was meaning to cut it, I threw it into the bottle of HCl-Cl.
Oops. Pretty soon, I had a very thin, very hollow, gold-colored shell sitting in the bottom of a bottle of HCl-Cl that now had a much more distinct green to it. The gold foil did dissolve eventually as well, but now I have unknown contaminants in my solution, though it seems likely that copper is among them. If I had to guess, I'd say it was probably gold plating on a brass coin, which means copper and zinc in my solution.
After perusing the forum looking for the remedy, I think I know what to do, but I'd like to verify with the experts:
- 1. Precipitate the dirty solution using SMB.
2. Use HCl to wash the precipitate to remove base metals until no more color comes out with the acid.
3. Wash the precipitate with water to remove remaining HCl.
