# The Stock Pot PGMs



## autumnwillow (Oct 18, 2016)

I plan to process my stock pot just for uhm. Fun and experience. Heh

Most of it contains PGMs, very little gold to no gold as I usually filter my pours and use stannous.
I am sure it contains iridium, more on palladium and a little platinum.
I use iron instead of copper to cement. So there should be copper in it too.

How does one go about processing it?

1) Filter
2) Dry
3) Incinerate
4) Dissolve in 50/50 nitric
5) Precipitate Palladium w/ DMG
6) I would use copper this time to precipitate silver and any remaining values. Then use iron after to separate the copper.
7) Process solids from Nitric digest in AR.
8) Check with stannous.
9) No. I will not precipitate Platinum yet. My lab isn't equipped for this yet. I'll just put this back in the stock pot.
10) Filter and precipitate gold if positive with stannous.
11) The remaining solids should contain iridium and silver chloride, dissolve this in ammonia. The remaining solids should be impure iridium and rhodium traces. Set this aside and label.

Not sure if I missed something, any comments would really be appreciated.


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## 4metals (Oct 18, 2016)

What type of material are you refining? And how much refined material is represented in your stock pot? 
Even if you check for complete precipitation with stannous there remains a few PPM of Gold which is undetected and usually drops out in time in the stock pot because of the excess metabisulfite in there. 


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## FrugalRefiner (Oct 18, 2016)

autumnwillow said:


> 1) Filter
> 2) Dry
> 3) Incinerate
> 4) Dissolve in 50/50 nitric
> ...


You're not likely to find any silver. I'm assuming that your stock pot, like most, handles a lot of solution with excess chlorides, so any silver would have ended up as silver chloride among the solids. Silver chloride will not dissolve in a nitric leach. Rather than precipitating the palladium with DMG (which can get expensive, voluminous, and requires more work to get to a metal), I'd cement it with copper.

Always remember that iron will precipitate everything below it on the reactivity table, not just copper. If there was any cadmium, cobalt, nickel, tin, lead, tungsten, antimony, arsenic, or bismuth in any of your solutions, they'll cement out along with the copper.



> 7) Process solids from Nitric digest in AR.
> 8) Check with stannous.
> 9) No. I will not precipitate Platinum yet. My lab isn't equipped for this yet. I'll just put this back in the stock pot.


Understand that once the platinum is dissolved, it is a toxic salt that just happens to be in solution. Precipitating it is not what makes it dangerous, though it's certainly easier for dried powders to become airborn. If you want to avoid the toxicity of platinum salts, you can dissolve the solids after the nitric digest in cold AR. It will dissolve any gold present without dissolving the platinum.

Dave


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## 4metals (Oct 18, 2016)

If the platinum came down from cementation it is finely divided platinum and there is a good chance even cold A/R will dissolve some of it. All of the PGM's that you want to store to refine later should be cemented with fine copper powder so they are in metallic form and then they can be stored as a powder without the inhalation and absorption through the skin hazards of the salts.


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## FrugalRefiner (Oct 18, 2016)

4metals said:


> If the platinum came down from cementation it is finely divided platinum and there is a good chance even cold A/R will dissolve some of it.


Thanks for the correction 4metals! I would hate to ever put anyone in harm's way.

Dave


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## 4metals (Oct 18, 2016)

Well some of it will likely dissolve and a good amount likely will not and then you've made extra work because you have to chase it in 2 places.


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## autumnwillow (Oct 18, 2016)

4metals said:


> What type of material are you refining? And how much refined material is represented in your stock pot?
> Even if you check for complete precipitation with stannous there remains a few PPM of Gold which is undetected and usually drops out in time in the stock pot because of the excess metabisulfite in there.
> 
> 
> Sent from my iPhone using Tapatalk



Mining buttons and all jewelry scraps/wastes.

Well actually I use the chloride from AR to precipitate silver in a nitric solution to recycle wastes. Since I am going to just use it for inquartation anyway. I was throwing the chloride wastes before in the stock pot. My AR solution was always clear though.

And yes, I am trying to avoid any platinum salts from being produced, I think there are a few members here who suffer from Platinosis already.


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