Anyone ever tried at home gold refining?

HDPE plastics actually work very well for this process. While the acids eat metals they don't touch the HDPE plastics. I just got done with the process and I'm going to melt the slug here shortly. I'll take a pic of the before and after.

 

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[Taps foot]

waiting!

 

Ok, It just went into the furnace... filters, concentrate, and all.

Here is your gold concentrate... the more brown the concentrate the more pure the gold.


On it's way to 1100 Degrees Celsius



Small spill!!! I'll consider it pouring a little out for my for my homies.

 

Not beautiful but my 22k test acid does not touch it. It weighs 3.6 grams. This was from a small test lot of about 100 grams of gold filled.

 

Not being familiar with gold or gold filled jewelry refining, is 3.6 grams good bad, or indifferent?

 

I think it's about in line with what I have been reading. One guy got 4.1g from 200g of gold filled. My lot was just a bit over 100g but had some older pocket watch cases which tend to have thicker plating. Overall I'm really pleased that it worked so well and I was able to get the process down to nearly a science.

 

I plan to scale it up to doing true scrap gold lots... This will result in a larger amount of gold. I just wanted to experiment on something that wasn't nearly as valuable until I got the process down.

 

I am also unknowledgeable. What is the difference between gold filled and gold plated?

 

It basically is science. Chemistry at work.

 

Gold filled is for all intents and purposes just really heavy gold plating... Could be up to 200 microns thick... The HGE and other types of plated are usually only up to about 10 microns thick. There is enough gold in gold filled to process like this and end up with a measurable amount of gold.

 

Thanks for the answer Matt
I didn't know there were that many types of goldware

 

Neat! Interested to see if you do it to larger scrap amounts.

 

I just dump my GF in nitric to dissolve the base metals, and filter the karat out.
I let my local refiner handle the rest.
Neat writeup!

 

The big reveal here for me was that it works so well to start with muriatic acid and sodium nitrate, instead of needing actual nitric acid. That stuff is quite expensive and hard to come by (and not very nice to have around).

I'm interested in @harris498's idea, too. I guess you could start with sulfuric acid instead of hydrochloric, and that way you wouldn't be making aqua regia -- but you'd need something other than cotton or paper to do your filtration, unless you neutralize carefully first (in some way that doesn't precipitate gunk back onto your gold). Sulfuric acid plus nitric acid equals nitrating acid, and turns cotton or paper into nitrocellulose. It won't go boom without provocation, but it won't hold up very well in your funnel, either.

See, this is the kind of chemistry that I swore off when I realized what a hassle it would be to deal with accidents. But it's sooo tempting to dust off the glassware and do a little experimentation...

 

The urea was used to neutralize the nitric acid before the precipitation process. The HCL was still acidic so when you add the storm agent the gold is the only thing that precipitates that isn't attacked by the remaining HCL. I filtered the gold and then neutralized the remaining HCL with lye.

 

Just to show. I scaled it up. This last lot brought 31.14 grams.

 

Now, that's worth some time and trouble.

 

I'll have it x rayed sometime this or next week to get a purity. I'd bet that it is at least .999 tho.

 

Very interesting thread Matt.