Link between SMB quantity and gold quantity

[nickvc]

I love these theoretical amounts as they are usually complete tosh unless you are working under strict laboratory conditions with very clean solutions ie no other metals no excess acids and at the correct temperature, they are good for a starting point but I wouldn’t bet any of my gold on them.
Theoretical chemistry and real world recovery and refining chemistry are almost two different subjects and a simple example is cleaning your gold powders in Hcl, theoretically Hcl cannot dissolve any of your gold but in reality it does, maybe not much but it still will hold some of your gold.
The answer to the how much precipitant you need is simple to determine you add it until a test using stannous shows there is no gold left in solution and the fact is your precipitant is a lot cheaper than the gold your after so if you use a little excess I think that’s still a bargain.

 

[nickton]

Copperas is a bargain but I wouldn't say SMB is really. I believe one pound of Stump out by Bonide sells for $9.00 now, and it goes fast...Perhaps I am too cheap, but I'm not crazy about paying that much for it. :G :G :mrgreen:

 

[g_axelsson]

Interesting thread that i had forgotten about.

Right now I'm split between copperas (make it myself from waste acid from the reverse plating cell) and SMB. When visiting Jon I had the opportunity to test several different precipitants. So today it's more a question about availability, whatever is closest to where I'm refining. It's more or less the same to me whatever I use and if I have a problem with contamination I'll just switch.

Göran

 

[anachronism]

Goran

The biggest eye opener for me was watching Kurt use copper dust to precipitate. It instantly used up any free Nitric and frankly the gold cleaned up very nearly as well as using other precipitants.

"Very nearly" is good enough for recoveries. 8) 8)

Edit: I remember 4metals telling me one night that it's a darned good precipitant and he was right. This was the first opportunity to give it a go.

Jon

 

[rickzeien]

Goran

The biggest eye opener for me was watching Kurt use copper dust to precipitate. It instantly used up any free Nitric and frankly the gold cleaned up very nearly as well as using other precipitants.

"Very nearly" is good enough for recoveries. 8) 8)

Edit: I remember 4metals telling me one night that it's a darned good precipitant and he was right. This was the first opportunity to give it a go.

Jon

How fine was the copper dust.

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[anachronism]

I'll go look at the container Rick and let you know later.

 

[g_axelsson]

Fine enough to not spot any grains in the copper powder. Like flour.




Göran

 

[snoman701]

It’s around 300 mesh.

Called atomized copper.


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[anachronism]

It’s around 300 mesh.

Called atomized copper.


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It's dust. It works. What's not to like? 8) 8)

 

[snoman701]

For it to work it has to be oil free. A thinly spread layer should sink, not float.

Probably easiest to put it in a spice like container so it can be sprinkled...if you put in a large dollop it tends to clump together as the noble metals precipitate, then form an insoluble layer. What’s worse is that clump will get HOT and melt in to the bottom of a bucket or barrel.

I use it to drop out pgm’s from AR following gold drop.


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[niks neims]

I have read it here that it is a good idea to alternate precipitants between recovery/refining drops... It seems like a very logical idea to me, also someone once mentioned that copperas handles dirty solutions better than SMB, so for what little recovery/refining I still do, I use Copperas for initial recovery drop and SMB for clean, refining drops, I don't know, SMB it just feels cleaner, the best would be SO₂ gas of course;

The atomized copper powder - so it's basically quick cementation? Surely it would only be used for recovery drop, not refining, unless you plan to wash your refined powder with nitric afterwards?

 

[anachronism]

The atomized copper powder - so it's basically quick cementation? Surely it would only be used for recovery drop, not refining, unless you plan to wash your refined powder with nitric afterwards?

Yes Nik. Absolutely correct - it's best for recovery. That given if you're on your game with cleaning it makes very little difference. You can still clean it using the 50/50 HCl/water method.

 

[niks neims]

Yes Nik. Absolutely correct - it's best for recovery. That given if you're on your game with cleaning it makes very little difference. You can still clean it using the 50/50 HCl/water method.

I'd still prefer to cement with a solid bar, though... much slower, but less potential contamination... Also I can't get my head around how can you dissolve away copper with just HCL, It's not the first time someone mentions it, and I am at a loss how would HCL without an oxidizer take care of copper?

 

[anachronism]

In theory it doesn't you're quite correct.

That's why as Kurt pointed out we didn't get to three nines. If you're testing, and careful you can ensure that you don't add a lot of extra copper.

The purpose is to get your gold here, and collate it for a proper refine. It's fast and effective and works best the premise that there's a fair amount to do in a limited time.

If you don't have those time limitations then sure go for the bar. I only tried a copper bar a couple of times and wasn't overly happy with the gold I got- and on balance this was a lot better all round.

If you think laterally- there's nothing to stop you starting with a spoon of copper and moving on to something else when the copper has used up any free Nitric that's lurking, which it all too often does no matter how well you think you've denoxxed with Sulphamic.

 

[niks neims]

In theory it doesn't you're quite correct.

That's why as Kurt pointed out we didn't get to three nines. If you're testing, and careful you can ensure that you don't add a lot of extra copper.

The purpose is to get your gold here, and collate it for a proper refine. It's fast and effective and works best the premise that there's a fair amount to do in a limited time.

There was this quote here somewhere (I don't think it was you, though the humor of it was very similar) regarding brute force gold recovery from e-waste, something along the lines "quit playing Mr. Little Chemist, just drop your gold by cementing it with copper, no need for fancy precipitants if you are not shooting for 3N up at least", I found it very funny and worth remembering

If you don't have those time limitations then sure go for the bar. I only tried a copper bar a couple of times and wasn't overly happy with the gold I got- and on balance this was a lot better all round.

To be honest, I gained a new respect for cementation when I did some silver in nitric- there is something very satisfying in the way copper bar cements out silver and it flakes of...

If you think laterally- there's nothing to stop you starting with a spoon of copper and moving on to something else when the copper has used up any free Nitric that's lurking, which it all too often does no matter how well you think you've denoxxed with Sulphamic.

I must say I would not feel comfortable mixing together denoxing and precipitation steps (there is no practical reason, I just like to filter pregnant AR to crystal clear right before precipitation, so I know that anything that comes down is "pure" gold) be it with copper, copperas or SMB; I must admit I cheat with urea (I know it is frowned upon, but cant understand why) for denoxing and found it works best for me (secound best, after not adding too much nitric of course)... I guess there is some preference of style in different techniques

 

[anachronism]

I'm completely with you regarding the silver precipitation with a copper bar. Yes it looks great too.

I used to be nervous about mixing precipitants. There's far too much water under the bridge now for that nervousness to remain because sometimes it just has to be done. Being logical about it, the approach that says if all else fails use a copper bar- is exactly that. 8) 8)

 

[niks neims]

if all else fails use a copper bar

oh, jeah, it has saved my gold from a mess a few times

It's right up there with "READ HOKES!" & "FORGET YOUTUBE" !

 

[kadriver]

For it to work it has to be oil free. A thinly spread layer should sink, not float.

Probably easiest to put it in a spice like container so it can be sprinkled...if you put in a large dollop it tends to clump together as the noble metals precipitate, then form an insoluble layer. What’s worse is that clump will get HOT and melt in to the bottom of a bucket or barrel.

I use it to drop out pgm’s from AR following gold drop.


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I tried cementing PGMs from a solution containing dissolved copper with zinc in my stock pot refining videos but the zinc dropped the copper with the PGMs. Using copper powder is a good suggestion. Will cement out the PGMs and leave the copper in solution. Wish I'd of thought of that back then. I've even got fine mesh copper powder in my cabinet. I must try this when I refine my stock pot next time. Someone said Rick recommended copper powder in the stock pot refining but it didn't click until just now.

Thank you,
kadriver

 

[nickton]

Referring to the reactivity series: What if you put some gold in the stock pot, to cement only PGMs first, since they are the only thing below gold on that list. Your first batch of black slime should therefore be only PGMs, which would be separated from the start, then you could cement the remaining solution first with silver to get the gold (and thus recover what you deliberately put in as well), then with copper to recover the silver, then finally with zinc, iron or aluminum to clean out remaining base metals.

This would be an ongoing series of cementations one could let sit in separate buckets-- and would require much less additional acid for the whole waste refining process. The only real problems would be the initial leap of faith and extra supply of gold required for adding to the stock pot to start with, and the extended soaking times needed.

(I hope that made sense)... Or did I misunderstand how it works?

I guess the main question I would have about this method is: How much gold would one need to cement those PGMs?


Please excuse if this is slightly off topic by the way, but I've been looking for a thread to post it to.

 

[butcher]

nickton,
You have theory correct, and understand how it works, but with silver, gold, and the platinum groups being so unreactive, or in the Nobel metal group, so close together in the series, it would be very difficult to cement the PGM's with gold...
It may be possible under some conditions, I do not believe it would work as well as copper or a more reactive metal...