Refining karat gold with Acid/Peroxide

[ragood]

I did an experiment where I melted a 1.6 gram 10k gold ring with about 6 grams of copper, resulting in an alloy of about 10% gold and 90% base metal, mostly copper. Then I put it in HCl and a little 3% hydrogen peroxide with an aquarium bubbler to generate CuCl2 to etch away the copper. After 3 days, I checked on it and there were brown chunks in the beaker that broke up easily. I let it run in the CuCl2 with the bubbler for another day then rinsed the brown chunks in distilled water and dried off the remaining water on low heat. The weight of the brown chunks after drying was 0.72 grams. There should be 0.67 grams on pure gold in the 1.6 gram 10k gold ring, so it appears that the CuCl2 dissolved most of the base metals.

I plan to use HCl and bleach to dissolve the gold and then precipitate it out with SMB.

Has anyone recovered karat gold with this method? Did I need to alloy the gold down to 10% or would the standard 25% gold alloy work? I reasoned that a larger proportion of copper would make the CuCl2 work better.

 

[Yggdrasil]

I did an experiment where I melted a 1.6 gram 10k gold ring with about 6 grams of copper, resulting in an alloy of about 10% gold and 90% base metal, mostly copper. Then I put it in HCl and a little 3% hydrogen peroxide with an aquarium bubbler to generate CuCl2 to etch away the copper. After 3 days, I checked on it and there were brown chunks in the beaker that broke up easily. I let it run in the CuCl2 with the bubbler for another day then rinsed the brown chunks in distilled water and dried off the remaining water on low heat. The weight of the brown chunks after drying was 0.72 grams. There should be 0.67 grams on pure gold in the 1.6 gram 10k gold ring, so it appears that the CuCl2 dissolved most of the base metals.

I plan to use HCl and bleach to dissolve the gold and then precipitate it out with SMB.

Has anyone recovered karat gold with this method? Did I need to alloy the gold down to 10% or would the standard 25% gold alloy work? I reasoned that a larger proportion of copper would make the CuCl2 work better.

Welcome to us.
You will benefit from studying more before you continue your journey.
We aim for 25% because then the Gold hold together in chunks and do not form hard to settle powders.
And the preferred method is to use Nitric since it will dissolve the Silver as well.

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/

Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/


Forum rules is here.
https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

 

[ragood]

I have read the Hoke book that I downloaded from the forum and I have also read the safety and waste treatment information. Thanks to the forum for providing that.

I didn't write it in my original post, but I am trying to avoid using nitric acid because it is difficult to buy. I alloyed with copper specifically because the CuCl2 solution is very effective at dissolving the copper.

I have used CuCl2 to recover gold shells from gold filled scrap, although that process took more than a month to dissolve the brass in the watch cases and band caps. Some pieces of gold filled get eaten away quickly and other pieces take a long time.

 

[Master Nater]

nitric acid difficult to buy in the US? one can have it delivered directly to your house. i ordered my first set from JSP. came in the mail. i plan on having another set from dudadiesel, soon, as it is much cheaper.

i've also been looking into possibly making nitric myself. apparently, one can make it OUT OF AIR. (or so i have seen on a few different DIY videos) yes, sorry guys, i've been watching youTube videos. has anyone on this site tried the arc production of nitric acid? there are a few different videos out there, but it seems that overcoming the moisture in the air causing an early reaction and introducing HNO3 instead of just HNO2 the vessel seems to be the issue. this should be easily overcome with a simple home-made de-humidifier (radiator in an ice bath) to drop out moisture in the air before sending into reaction vessel for air exchange. or potentially using the air off of a dehumidifier or air compressor, to produce HNO2 with. but it appears to be another wonderful engineering project for me.

 

[Golddigger76]

nitric acid difficult to buy in the US? one can have it delivered directly to your house. i ordered my first set from JSP. came in the mail. i plan on having another set from dudadiesel, soon, as it is much cheaper.

i've also been looking into possibly making nitric myself. apparently, one can make it OUT OF AIR. (or so i have seen on a few different DIY videos) yes, sorry guys, i've been watching youTube videos. has anyone on this site tried the arc production of nitric acid? there are a few different videos out there, but it seems that overcoming the moisture in the air causing an early reaction and introducing HNO3 instead of just HNO2 the vessel seems to be the issue. this should be easily overcome with a simple home-made de-humidifier (radiator in an ice bath) to drop out moisture in the air before sending into reaction vessel for air exchange. or potentially using the air off of a dehumidifier or air compressor, to produce HNO2 with. but it appears to be another wonderful engineering project for me.

Yes it's not difficult to buy at all, even Walmart sells it online.

 

[ragood]

I started another batch that is 25% gold and 75% copper and other metals with a total weight of 51 grams last night. I'll let it bubble for 3 or 4 days and then check on it. If it gets down to around 13 grams of brown chunks it will be successful.

 

[Yggdrasil]

I started another batch that is 25% gold and 75% copper and other metals with a total weight of 51 grams last night. I'll let it bubble for 3 or 4 days and then check on it. If it gets down to around 13 grams of brown chunks it will be successful.

If you have 25% Gold and 75% Copper, that is all.
You have to calculate the amount of Gold and then the amount of base metals and add what is needed to achieve 25% Gold.

 

[ragood]

I checked on my second batch in the CuCl2 solution after 2 days and it's definitely disintegrating the inquarted copper/gold pieces. The attached picture shows some of the metal that I scooped out and rinsed off with distilled water. There are still some identifiable copper colored pieces.

 

[Notabiker]

I typically have an A/P pot and a Nitric Pot. When time is not being used on either one you can throw your stuff in the one that time is not being used. Get it Got it Good . Use your time wisely as time is limited.