Best Approach for Recovering Gold Filled (overlay)

[Anonymous]

Hi all, I'm very new to this and appreciate all the great posts and wealth of information on this site. It would seem that if you look long and hard enough you will likely find the anwser to any question. I've found a lot of good info on processing gold plated (electrolytic recovery) and processing of Karat gold (ie AR and all the steps), but I'm uncertain about how to process gold filled jewelry. Afterall it is Karat gold but is only a thin layer over the surface. As I understand it, typically the percent gold karat is 1/20 of the total weight.

So whats the best approach for proceessing gold filled? If I had to guess I would try electrolytic recover first? Some insight and advise from the pros here would be greatly appreciated.

Thanks in advance
Tilly :wink:

 

[Noxx]

I would recommend reverse electroplating (electrolytic recovery).

 

[lazersteve]

Tilly,

Welcome to the forum and thank you for posting.

Gold filled scrap will not do well in the cell. It is best processed using inquartation methods. That's basically to say dissolve it in diluted nitric acid. You should heat it to redness with a torch before the acid treatment to remove any oils or combustible surface trash. Then dissolve it in a mixture of 1 part 70% nitric acid and 1 part distilled water. Heating will speed the reaction. Be sure you do this in a well ventilated area as you will produce NOx gases which are very hazardous to your health.

As a side note I am in the process of producing a tutorial on gold filled scrap. Harold has been kind enough to check my procedure and I'll begin production very soon.

I have lots of videos in store for the forum, but these things take a lot of my free time of which I have very little.

Feel free to ask any questions.

Here's the standard 10 cent tour posts:

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Have fun!!

Steve

 

[Noxx]

Steve, do gold filled can be considered as heavy plated material or it's more than this ?

 

[lazersteve]

Noxx,

Gold filled is typically better than gold plated. Think of gold filled as hollow karat gold that is mechanically filled with or applied to a base metal. I'm not certain exactly how it's made, but this analogy will put it in perspective when comparing gold filled to gold plated.

Steve

 

[Harold_V]

Gold filled scrap will not do well in the cell. It is best processed using inquartation methods.

I hope my comments will be accepted in the spirit in which they're offered.

The inquartation comment implies that gold is "quartered", which need not be the case in gold filled. Otherwise, the process is much the same as inquartation in that the base metals are dissolved with nitric acid, leaving behind only (in theory, anyway) the values.

Understand that gold filled can be used in place of other added metals when inquarting karat gold, but it need not be used, and can easily be processed simply by dissolving base metals with nitric and water. That's what Steve is saying.

I didn't worry about using distilled water when dissolving base metals, but I also further processed my waste materials by furnace, recovering what little silver was converted to chloride by tap water. If you do not follow that procedure, use distilled water, but allow the solution to cool and settle lead nitrate before recovering traces of silver. Once you've decanted the solution (after cooling and settling), you'll be able to recover the small amount of silver contained within on scrap copper, or if you don't mind working with silver chloride (not recommended), precipitate the silver with salt or HCL.

If you have no karat gold to process, simply follow Steve's suggestion. It's always smart to heat anything you introduce to acid----heat it hot enough to burn away anything undesirable---especially oils, which will suspend fine particles of gold and make recovery from the oily surfaces of your container difficult. Dissolve the base metals with nitric (or equivalent), separate the remaining solids from the solution, then process the solids with AR.

There is an additional step you may wish to pursue. It's not uncommon for gold filled to have soft solder included in it's manufacturing. The remaining solids, once introduced to AR, can be difficult to filter. By incinerating the solids first, to kill all traces of nitric, then boiling in HCL, you'll dissolve and remove troublesome compounds that make filtering your gold chloride solution difficult. I recommend this step for gold filled, especially if the source is eye glasses. If this makes no sense, please ask for clarification-----it's a very important procedure to know.

Harold