first try

[Baja Bob]

I have went through my first attempt at dissolving scrap gold. took some plated pins and leached them in an AP mix for 2 days (to remove base metals), then took the solids ( gold?) and filtered, washed and leached them in a clorox - muratic mix. Instead of a golden yellow liquid I was left with a blue green liquid. how do I proceed? do I try and remove the copper first then use SMB to drop the gold or can I just drop the gold with SMB first? thanks Baja Bob

 

[Harold_V]

Don't jump to conclusions. You may not have any gold in solution. Base metals will quickly precipitate gold that is dissolved----but it won't necessarily look like gold. You could expect anything from tiny gold flakes to a dark brown or black powder. If your solution is blue, chances are very good that it contains nothing of value.

It is in your best interest to carry out these operations to fruition, and do not rely on time alone. If two days isn't enough to dissolve base metals, by all means keep at it until they are all gone.

Assuming your solution tests for gold (you have tested with stannous chloride, right?), you can recover what gold is in solution with a precipitant of your choosing.

Do not discard anything from this operation. I get the idea that you're not following prescribed procedures and may well lose some of the gold if you do. If I had the material, I'd incinerate everything to eliminate carbonaceous materials, then start over, dissolving all the base metals until they were totally in solution. The end results from refining are always better if you can eliminate all traces of other elements.

Harold

 

[lazersteve]

Bob,

AP works best on scrap like fingers, whole cpus, and pins that are still in the header plastic.

It will dissolve loose pins also, but this takes quite some time, and your gold may actually end up as the dark powder instead of foils and flakes as Harold mentioned.

When you filtered the foils from the AP where they washed ith HCl throughly before moving to the HCl-Cl?

The key is to keep the volume of the solution great enough to absorb the base metals present and also to keep the peroxide content low enough that it doesn't dissolve the gold foils and flakes that are produced.

Excess peroxide will certainly dissolve the gold foils into the solution, which will latter be pushed out of the solution as the base metals dissolve. The gold then ends up as a dark fine powder instead of gold colored foils.

Mix up some stannous and check the AP solution for dissolved gold. If the leftover AP has a bright yellow ring around the top of the liquid when you swirl it, it most likely contains dissolved gold.

If it is barren then check the bottom of the bucket for a dark colored fine powder this will contian your gold.

How many pounds of pins did you process?

Steve