# Sulphuric cell.



## nickvc (Mar 24, 2010)

Hope one of our clever members can answer this for me,can you use the sulphuric cell to strip gold off silver and if so will it attack the silver base?


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## Harold_V (Mar 24, 2010)

A sulfuric cell will strip both gold and silver, so, yes, silver will be removed as well. 

Harold


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## nickvc (Mar 26, 2010)

Thanks for that Harold,will it dissolve a quantity of the silver or just a small amount? some silver going into the mix wont bother me to much as the customer has volumes of silver scrap with gold plated items mixed in which he doesnt get paid for so he wants to try and maximise his returns.I did think of setting up a small silver cell to reclaim the gold but wondered if the sulphuric cell might be easier,your thoughts as always are welcomed.


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## qst42know (Mar 26, 2010)

Would the gold quit stripping once the silver was exposed? In the cell.



Alternately. Could gold plated silver be stripped with AR? 

It should have little affect on the silver, but would it finish removing the gold or be stopped by the intimate contact with the silver.




edited for clarity.


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## butcher (Mar 26, 2010)

Nick, if we know more about the items it may help, with the answers, are these plated items, or gold plated silver items and so on?


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## Harold_V (Mar 26, 2010)

nickvc said:


> Thanks for that Harold,will it dissolve a quantity of the silver or just a small amount?


That's a matter of timing. If you allow a silver item to remain in a stripping cell long enough, in theory, at least, it can be completely destroyed. That, of course, wouldn't happen, because at some point the item breaks in to small pieces and may not have continuity. Done in a copper basket, however, that likely would not be the case. 

It's not clear to me if you can strip gold completely when it is plated on silver. It is possible that once the item is perforated, a stripping cell may favor the silver over the gold, so getting a complete strip of gold without taking a considerable amount of silver may not work. I simply don't know. I know that stripping with cyanide, when gold is plated to copper, and there is no barrier (nickel) beneath the gold, that the process works very poorly. I know that from personal experience. 



> some silver going into the mix wont bother me to much as the customer has volumes of silver scrap with gold plated items mixed in which he doesnt get paid for so he wants to try and maximise his returns.I did think of setting up a small silver cell to reclaim the gold but wondered if the sulphuric cell might be easier,your thoughts as always are welcomed.



It would be my humble opinion that you should give it a go! What better way to learn how it might work? 

The point to remember is that you don't lose anything.. Even if you strip a serious amount of silver in the process of recovering the gold, it's still there to be recovered. 

Silver that is gold plated can be processed easily by using the material in inquartation. Problem is, you may not be able to identify the amount of gold that comes from the process. It would work fine for an individual processing his own materials, but not so good if you are processing for a third party. Then, an assay could still solve the riddle. All items are melted, stirred until they are homogeneous, then poured to shot. The rest is nothing more than math, coupled with a reliable assay.

Harold


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## nickvc (Mar 26, 2010)

butcher said:


> Nick, if we know more about the items it may help, with the answers, are these plated items, or gold plated silver items and so on?


The items are all from silver scrap, most will be gold plated sterling silver the plating between 9carat and fine gold,high quality jewellery :lol: Harold as usual your opinion is greatly valued and i must admit the temptation to try the sulphuric cell is very strong, but this isnt my material, and i dont refine except in small quantities anymore ,so using the material to inquart is not an option either, setting up a silver cell seems the best option,i love the challenge cant help but keep having a play. 8)


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## butcher (Mar 26, 2010)

For gold plated sterling I like Quest 4 to know's idea Aqua Regia or HCL/Bleach, for karat I would in quart first, Steve’s small furnace should work for small lots.
then there is the saturated salt electrolytic cell and the Coors cup membrane method to consider also.
If mostly silver and plated what about this-as a pre-step to recovery
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=2868&start=0&view=print


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## nickvc (Mar 27, 2010)

butcher said:


> For gold plated sterling I like Quest 4 to know's idea Aqua Regia or HCL/Bleach,


Now thats a good simple idea that would work,i know the silver will not react in AR not sure of the HCL/Bleach as i have never used it but i can have a play 8) the silver could be scrapped quickly too which will keep the guy happy. Thanks for the replies fellas can have a play with this now.


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## Harold_V (Mar 27, 2010)

nickvc said:


> butcher said:
> 
> 
> > For gold plated sterling I like Quest 4 to know's idea Aqua Regia or HCL/Bleach,
> ...


My concern would be the dissolved gold being cemented on the silver, with the end result of the gold mixed with silver chloride. Assuming that was the case, it isn't a clean operation as one might hope. 

I do not know that that would be the case. If you attempt the process, a report on your success would be interesting. A simple test of dipping a piece of silver in some gold chloride might yield the required information. If I still refined, I'd do it myself. 

In support of the concept, I seem to recall that silver was the buss bar of choice for a Wohwill cell. I chose to use titanium instead, but my cell was never put in service. I have no clue how it would have worked. 

Harold


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## nickvc (Mar 27, 2010)

Harold i always have a few chemicals around to have a play so i am going to try the AR process and will inform you of the results.The idea is to leach the gold off the silver and allow the values to be recovered , the big boys ignore very low Au content or charge so much its uneconomical to be paid for,as we all know its a whole lot more work to recover the Au from the Ag especially from a cell :roll: If some silver goes into the mix it really wont matter as the purpose is to concentrate the values not refine them,as i have said before refining isnt worth the effort here in the UK as you get very little if any more for high grade Au the only reason to do so is to reach a product that can be assayed.


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## qst42know (Mar 27, 2010)

I just happened to have a bit of AuCl and a sterling spoon.

A quick dip discolored the silver, and a 10 min. soak shows the gold is depositing. It may stop at some point when the copper in the alloy is encapsulated but it doesn't look like it will solve your problem.

That answered that question. 

Another barrier I hadn't considered is the karat value of the gold plate.


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## Anonymous (Mar 27, 2010)

I recover gold from fashion jewerly by putting it into a tall plastic container with a spacer of marbles underneath the material. Then add HCL, and a dose of concentrated bleach evaporated to 1/2 orginial volume (foams up real flast, removes the flash coating and falls back down into the marble spacer. (caution, lots of chlorine fumes)

I am sure that I do not get 100 percent of the gold, but it does leave the nickel layer showing nice and bright.

edit
I should add this works super great on busted up porcelian/glass pieces with the gold plating on them.

Jim


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## qst42know (Mar 27, 2010)

It might still be worth some experiments with the items you have to process. AR may consume the reachable copper in the alloy and the depositing might be prevented. However this may be completely ineffective on 18k over silver. It would be interesting to see your results.


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## Harold_V (Mar 28, 2010)

You might also create enough silver chloride on the surface that chemical action ceases, both in dissolving the silver (via cementation), and in cementing the gold. Timing could be a factor.

Harold


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## qst42know (Mar 28, 2010)

I thought it might be useful to know the condition of the solution the spoon was dipped in was a small amount of dirty gold from a stripping cell. This was dissolved in HCL/Cl and brought to a boil to kill the active chlorine. The spoon was dipped in this cold solution before it was filtered. Sterling may act differently in an active HCL/Cl solution or perhaps an AR solution.


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## butcher (Mar 28, 2010)

I agree


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## Harold_V (Mar 29, 2010)

The only question I would have is what becomes of the chlorine that is liberated when gold chloride is reduced to elemental gold? Seems to me you can't avoid some exposure. I expect it will have an effect on the silver---it's a matter of how much. 

Where are the chemists when we need them?

Harold


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## qst42know (Mar 29, 2010)

Thinking I might be able to remove this flash plate as fast as it was put on. I mixed up 20ml of HCL and 10ml of chlorine bleach. It quickly built a grey layer and quit doing anything. A few strokes with a polish cloth and the gold layer is still on beneath the layer of grey smut. So at this point I would guess the gold plate is somehow protected by the silver under it.


So I resorted to a micro-mini cell, a 50ml beaker. The gold was removed and the silver was being digested. However silver in a cell acts like a wet adherent soot. I had to rub this black coating off in the rinse with a gloved hand to see that the gold was released.
I think a cell may work better for your material if you could rig a tumbler to let the parts themselves do the rubbing.

Is nitric acid to remove the silver directly out of the question?


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