Non-Chemical Purification of black cell powder before the AR process?

[husker4515]

Doesn't make sense to wash your black cell powder in a HCl or 50/50 Nitric wash, to rid any base metals before the AR process? In my search I find only GSP to mention doing this. Am I missing something? Purity is my ultimate goal.

Thanks,
Mike

 

[Barren Realms 007]

You need to wash your powder in water till no more color shows in the water and then wash them in HCL to remove impurities.

 

[lazersteve]

Here's a write up I did on washing black powder from the cell:

Black Powder from the Cell


Steve

 

[Harold_V]

Doesn't make sense to wash your black cell powder in a Hcl or 50/50 Nitric wash, to rid any base metals before the AR process? In my search I find only GSP to mention doing this. Am I missing something? Purity is my ultimate goal.

Thanks,
Mike

Bear in mind, I never operated the large water cooled stripping cell I built.

Having stated the above, not only would I do an acid wash prior to dissolution, I'd also incinerate the lot before the acid wash. Why not? No harm can come from the operations, and you certainly can improve the material by each procedure.

Harold

 

[nickvc]

Doesn't make sense to wash your black cell powder in a Hcl or 50/50 Nitric wash, to rid any base metals before the AR process? In my search I find only GSP to mention doing this. Am I missing something? Purity is my ultimate goal.

Thanks,
Mike

Bear in mind, I never operated the large water cooled stripping cell I built.

Having stated the above, not only would I do an acid wash prior to dissolution, I'd also incinerate the lot before the acid wash. Why not? No harm can come from the operations, and you certainly can improve the material by each procedure.

Harold

Mike if purity is really your goal I'd take Harold's advice to the letter....if you have seen pictures of the product he used to produce you would know why 8)

 

[dtectr]

Doesn't make sense to wash your black cell powder in a Hcl or 50/50 Nitric wash, to rid any base metals before the AR process? In my search I find only GSP to mention doing this. Am I missing something? Purity is my ultimate goal.

Thanks,
Mike

Bear in mind, I never operated the large water cooled stripping cell I built.

Having stated the above, not only would I do an acid wash prior to dissolution, I'd also incinerate the lot before the acid wash. Why not? No harm can come from the operations, and you certainly can improve the material by each procedure.

Harold

Not sure if I have all the facts, but when I incinerated prior to dissolution, I believe the lead acted as a collector & alloyed with the gold (there is always SOME lead from the anode, even in minute amounts its enough to cause purity issues), resulting in solids at lower temperatures than red heat, that would not dissolve in HCl-Cl. If you boiling water rinse until until no more color shows, with thorough stirring, you are removing the nickel & copper sulfates, which are water soluble (see solubility list from lazersteve's forum guide). You will be left with a little sulfuric still in solution, which keeps most of the lead as insoluble lead sulfate, which filters easily after HCl-Cl dissolution.[Thanks to harold, for this factotum, which was proved true, in practise]

Knowing your feedstock is important - if you know, for example, that all you have is gold-plate, over nickel over flash-plate of copper, for example, and are monitoring your process closely, you shouldn't have to worry about "unknown" contaminants. You should NEVER get to your primary base metal, anyway, so it should be a nonissue. Some HCl washes followed by hot water would take care of everything that got by. The above process would account for all of the above. There simply won't be any base metals left to mess with. If you are concerned about final purity, re-dissolve & drop again after washes. This is the recommended procedure for ultra-pure gold, namely, 2 dissolutions & precipitations.

If you are careless & let the item being stripped to linger too long &/or if you allow your sulfuric to become diluted, you will then be introducing other unnecessary issues that could be easily prevented.

EDITED: Credit Harold for benefit of sulfuric. I knew it was SOMEBODY ...

 

[dtectr]

of course - I'm a moron. I'm not sure if these post in the correct order.



did I do this right? Anyway, here's the dish, after melt ...

And resulting button ...

EDITED: I AM a moron - anyway, I think I got it right this time... dtectr

 

[Barren Realms 007]

Looks like you are getting there. Nice looking button.

No you are not a moron, it is just a learning experience you are going thu. 8)

 

[Harold_V]

when I incinerated prior to dissolution, I believe the lead acted as a collector & alloyed with the gold (there is always SOME lead from the anode, even in minute amounts its enough to cause purity issues), resulting in solids at lower temperatures than red heat,

If that's the case, I certainly would second guess my suggestion of incineration prior to the acid wash. It's important that the material not end up fused, otherwise washing will limit the benefits. The HCl wash is quite important in the scheme of things, insuring the resulting gold chloride solution filters without issues.

Harold

 

[lazersteve]

I wholeheartedly agree with incineration where it is needed when you have suspected tin, organics, or carbon contamination, but for the black powder from the cell, I don't incinerate.

That is why I left it out of the process.

Steve

 

[husker4515]

Processing large amounts of pins in my copper basket at one time, I have notice that the base metals, (tin, zinc and copper) start to deplete once the gold is gone. That is why a posed the question about doing an acid wash before dissolution.