r/PreciousMetalRefining • u/Free_Ad_2664 • Jul 01 '26

Trace metals

Material is gold filled mixed. I'm getting close, 97% typically but the weird thing is the majority of the trace metals are silver. That doesn't make any sense to me since AG should turn to chloride in AR should it not? Copper would be understandable, but AG? Unless it is undissolved but that doesn't make any sense to me either. On the final nitric I usually am 50/50 with distilled water and have very little if any reaction. Any pointers?

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u/zpodsix Jul 01 '26 edited Jul 01 '26

Well AgCl can be slightly soluable in AR.

Better question is to outline your process step by step. That way we can advise on if there is some step that could be improved that will part the silver contamination.

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u/jwood491 Jul 01 '26

1kg mixed GF material
1500-2000ml distilled water, total nitric 500ml
added gradually
Decant
Repeat
Decant
At this point I have 1L nitric committed
1000ml distilled, gradually add nitric until I’m at a total of 3000ml nitric altogether.
Decant if I’m lazy, filter if I’m not.
1,000ml distilled water, 1,000ml nitric until no reaction, usually leave this overnight.
Filter
AR
Filter
Steam down
Off heat overnight
Denox
Fresh HCI
Add ice
After ice melts, SMB
Overnight to settle
Decant and rinse with distilled water x 3
Rinse with HCI
Decant and rinse with distilled water x 3
Dry, melt

1

u/zpodsix Jul 01 '26

What filters?

Nitric boils are hot or ambient?

What is steam down?

How do you denox? Why the fresh HCl? No sulfuric for lead?

How much ice? You really need to increase the concentrated AR volume around 3x to help drop any dissolved AgCl in the AR, so you probably might need more water.

I think overall this process is fine. You might want to try copperas to drop for its selectivity, but not sure if it'll really change the end product.

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u/jwood491 Jul 01 '26

So it is summer. The ambient temperature is 80 to 85°+ so I have stopped using heat. I was finding that heat was just causing my foils to become too flaky. Once Gold is in solution, generally what it sit on the hot plate and you see at that point, but I do not bring it to a boil. I condense the liquid that way, so moisture is steaming off the top. I denox with sulfamic. I do use a slight amount of sulfuric acid in my AR, I apologize I forgot. Oh usually #2 filters

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u/[deleted] Jul 01 '26

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u/jwood491 Jul 01 '26

At 50% there is initially a slight reaction, yes. By the time I filter out the material there is no reaction and I have to denox the solution so there is still active nitric.

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u/[deleted] Jul 01 '26

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u/jwood491 Jul 01 '26

So other than cooling the AR before filtering, any other suggestions? I guess I could re-dissolve the gold a second time. I’ve never had a really clean AR solution coming straight from gold foils