Mixed metal gold bar recovery issues.. HCL+H2O2

[Owen_Lindsay]

Great thread thank you, and il keep my eye out for appropriate cook ware to use in my processes

 

[FrugalRefiner]

The best shopping for Corning ware is at yard sales. I usually pay about $1.00 per piece.

Dave

 

[Martijn]

I would use a thick ceramic plant pot but I am afraid it would crack sitting on a naked flame .

That gave me the shivers.
Please stop what your doing!!! Don't hurt or poison yourself by making mistakes like that.
Put the acid away safely and study. Get some proper equipment.
Martijn.

 

[Owen_Lindsay]

don't worry , i havent employed the use of the ceramic plant pot, i was just chucking out questions to ascertain structural integrity of said item and also get suggestions, as with things in question like that i don't jump in i realise the hazard involved.

unfortunately keyboard strokes don't give adequate give a reflection of a persons naturally cautious nature.
mixing chemicals is one thing knowing what goes in and what should come out, playing with chemical and fire and unknown variable is another and that why i ask for advice.

thank you for your concern, i have a hoke's book on PDF now and the long read begins!!

thanks all

 

[anachronism]

Owen

Hi. Lab glass is pretty cheap here in the UK. 8) 8) 8)

Jon

 

[Owen_Lindsay]

cheers everyone


ill put some money aside for buying proper kit ..

i have a nice rich yellow coloured solution that still isn't dropping with smb,
the solution was heated for a couple hours on low heat outside in a glass cook ware thick heat proof pyrex dish not exposed to naked flame, still no drop

i read (can't remember where, likely this forum) that addition of NaOH will aid precipitation , it would drop all metal from solution but down the reactivity series as the Ph increases, i'm no chemist whizz but trying looking at the equation, it looks like i would end up with more SO2 gas produced,NaCl,H2O and of course gold precipitation

does that sound about right or is that statement only valid for untainted auric chloride solution ?

purity is not issue at present, im looking to get it from solution and re-refine once I have got the basics mastered.


:G

 

[Owen_Lindsay]

For stock pot solutions, can anything go in the stock pot from all stages of the recovery process or should you discard the solution from spent drops?

looking to get a nice big plastic drum and chuck in some old copper wire and pipes.

 

[anachronism]

Are you testing the solution for gold or just thinking that because it's yellow that it must contain gold?

Jon

 

[Owen_Lindsay]

stannous tested and instant colour change to pretty much black

 

[anachronism]

stannous tested and instant colour change to pretty much black

Good that works.

You'd be amazed how many people we get here who don't do that. 8) 8)

 

[Owen_Lindsay]

Lol, I’m a noob but am a quick study.

Once I had attempted a few small drops I made sure stannous was on hand to test residual solution.


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[g_axelsson]

No, don't add NaOH, it will precipitate everything in a black goo of metal hydroxides, your gold included.

If you have gold in solution but it doesn't precipitating with SMB, then I can only see three reasons.

1. The gold dissolves again, you still have oxidizer left in solution.

2. It isn't SMB you are adding. HCl and SMB gives a vigorous reaction, giving off SO₂ as a gas. Don't put your nose in it, it will knock you off your socks, but if you get a whiff of it you will smell a characteristic smell of sulfur dioxide.

3. The pH is close to neutral. Add a bit HCl and it will precipitate the gold. Easy to test with a pH strip, or just add a bit of HCl, it never hurts.

I have personally done 1 and 3. 1 several times but once number 3, I was quite baffled until I understood what was happening. I evaporated the solution to denox it and I forgot about it. When I returned the gold chloride had dried out and I used water to dissolve it again. When I added SMB nothing happened for a long time, then I added a bit of HCl and the gold just came crashing out, everything dropped in seconds.

If nothing else works then put a piece of solid copper in it to cement gold back from solution, then just start over.

Göran

 

[Owen_Lindsay]

Awesome stuff thank you , that helps explain the following a lot.

I decanted a bit off and as you said I got black and brown goo, I initially thought I’d done something to precipitate gold iii oxide but it was far too soluble, I slowly dried it and then I added it to more hcl and I’m 80% sure I got hydrogen sulphide being evolved. (Distinctive rotten egg smell) further addition of NaOH made black goo, it must contain sulphur and gold as well as any other dissolved metals. Sulphur being high on the reactivity series so getting dropped out first I assume...

I added the solution to my stock pot and chucked in some copper, now have lots of grey precipitate. Time to check it’s content.

All very exciting.






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[Owen_Lindsay]

So far mostly silver, time to return it to the stock pot for longer for further cementing out !


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