# Copper sulphate breake down cell



## Silverlord (Jan 26, 2017)

Hi,

Today I use a silver nitric cell as a "brake down" cell. This is acid effective and works fine. I can run about 3 kg scap silver ( 80% to sterling) before the electrolyte is too contaminated ( it is a 3 liter cell). 

Since I am lazy , I have lately thought of the possibillity to use a copper sulphate cell instead, using the copper refining process to separate copper from silver. Then the cell would "never" be contaminated. The copper goes to stainless steel cathode and silver stays as "slime" at the anode. The electrolyte would from the beginning be car battery sulphuric acid. 
Silver slime would be harvested regurlarly and then be treated with a small amount of diluted nitric acid to further purify, before washing and melting down to anode for the refining cell.

Would this be possible? Can sterling silver be processed in a copper refining cell?

/Jan


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## nickvc (Jan 26, 2017)

Jan welcome to the forum.
Could you please remove the swear word in your post as many will find it offensive.
As to whether a copper cell could work with sterling silver the answer is no, all electric refining processes need high grade feed stock at least 95 percent and preferably higherof the targeted metal, if you added lots of copper then it's a possibility.
If you are processing coin and sterling silver with a cell you can use it longer by stopping it and adding more nitric to increase the silver content, dissolving some of the refined silver, compared to the contaminates especially copper, it will not work forever but you can stretch its working life.


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## Silverlord (Jan 26, 2017)

Hi, 
thanks for you answer.

Do you know this by own experiance and testing?

I find it difficult to belive that all electric refining processes need the feed stock to be 95% pure. As I stated in my first post, the brake down cell I am running now, is fed with silver down to 80% pure...

The reason for the copper sulphuric cell is not to get 999 pure silver, but to get feed stock to the silver cell.


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## nickvc (Jan 26, 2017)

The problem with running low grade feed stock is that the electrolyte will foul very quickly.
Thinking at tangents if you added the already refined silver to your silver scrap to increase its purity, use your sterling for your electrolyte that may increase your throughput of scrap, when I ran my cell I used additions of nitric added to the electrolyte to dissolve more silver to keep the copper percentage low enough to allow the cell to keep running and produce more fine silver, once the electrolyte has fouled the cemented silver from it once well washed can be melted with your sterling and lower grade silver, it's all a balancing act.
Palladium did a well presented video showing how much silver can be put through a cell and how the copper builds up to foul it, there are ways to increase the amount of silver you can process but there is a limit which is impossible to exceed.


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## Silverlord (Jan 26, 2017)

Yes I know that copper builts up in the nitric cell. That is the reason I would like to make the first step of the purification in a copper sulphate cell.

The idea is that scrap silver in a sulphuric cell do not contaminate the electrolyte and can be "endless", just harvesting copper from cathode and silver slime from anode...

Note I am not talking about nitric cell.

First purification in sulphuric cell woud save alot of acid, and minimize spent electrolyte.


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## saadat68 (Nov 6, 2017)

Hi
I want to know why we can not add sterling to silver cell as an anode ?

If we add silver sterling as an anode to silver cell and refine them twice or more 
Can we get 999 silver this way ?

I want to know why we can not add sterling to silver cell as an anode ?


> As to whether a copper cell could work with sterling silver the answer is no, all electric refining processes need high grade feed stock at least 95 percent and preferably higherof the targeted metal, if you added lots of copper then it's a possibility.


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## Topher_osAUrus (Nov 6, 2017)

saadat68 said:


> Hi
> I want to know why we can not add sterling to silver cell as an anode ?
> 
> If we add silver sterling as an anode to silver cell and refine them twice or more
> ...



You can, (in a thum/moebius/stainless bowl cell with silver nitrate as the electrolyte) 
-it just fouls the electrolyte quickly.

The copper sulfate cell needs a lot more copper in the anode to function properly, as nick stated above. And with that much silver to copper, the electrolyte can and will actually dissolve and deposit the silver on the cathode too. (I will have to check my notebook for the reference to that in literature, but I know Ive seen it mentioned twice)


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## saadat68 (Nov 6, 2017)

> You can, (in a thum/moebius/stainless bowl cell with silver nitrate as the electrolyte)
> -it just fouls the electrolyte quickly.


Thanks 
Do you talk about this process ?
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=50&t=2868&start=60


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## Topher_osAUrus (Nov 6, 2017)

saadat68 said:


> > You can, (in a thum/moebius/stainless bowl cell with silver nitrate as the electrolyte)
> > -it just fouls the electrolyte quickly.
> 
> 
> ...



Yes and no.
In that post, steve is revitalizing copper nitrate to free nitric and silver nitrate, with a little bit of copper nitrate, with a cathodic deposit of cement(ish) silver.
Its just another flavor of breakdown cell.

When we use the terminology breakdown cell, we basically mean we are just breaking down the low grade alloy of silver, and getting it into a more pure state so it can be reran in a high purity silver cell.

A small caveat is that silver cells run better with a little copper nitrate in the mix, so you can start off with pure silver nitrate electrolyte and run it for awhile (with sterling as the anodel and suffer no ill effects. Eventually though, it will lose too many silver ions from the copper replacing them (copper has 2 nitrate ions, silver 1 in their respective formulas) and when it gets past a certain threshhold the cathode deposits purity begins to suffer.

I could literally write 50 more paragraphs on it probably, but I am rushing to get a couple things done (and typing this while driving -tisk tisk), so I cannot. But, I can say this -search breakdown cell, search the silver subforum, and read read read it ALL.
Trust me, it will help you dearly


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## UncleBenBen (Nov 6, 2017)

Topher_osAUrus said:


> and typing this while driving



Christopher, you have enough going on to be adding in a risk like that! :lol: 

But seriously though, hang up and drive!!

P.S. This has been a public service announcement telepathically sent to me by your mother.


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## Topher_osAUrus (Nov 6, 2017)

Nothin but empty 4 lane highway for miles, if its not windy, my knee can steer like a champion!

...its illegal to text and drive, but you know what isnt? Writing a longhand letter... Sewing a shirt... Eating ...
:lol: 

Back to it

-saadat, in practice, if there isnt a lot of material to be ran you can technically dissolve sterling for your electrolyte (and filter it crystal clear), then use more sterling to make anodes for the cell... Generally I like to run between 150 and 200g Ag per litre initially, but, it is possible to run less. You just have to go about it at a significantly slower rate so the cathodic potential for coppers deposition isnt reached, and it will stay in solution instead of getting deposited with silver, therefore leaving a more pure deposit. (This is only true to a certain extent, I am not sure what the equilibrium point is for Ag/Cu at such low potential)

A little anecdote
Awhile ago, my silver cell started making bad crystals, so i set the electrolyte aside and was going to cement it. A couple days later, I bought 700 or so grams of sterling.. I wanted to run a breakdown cell, I figured, since I had the spent electrolyte I could just do as steve did in his thread. But, I wanted to try something first. In a book I read it mentioned running with a very low potential and current flow, impurities dont have near the tendency to deposit.

So, instead of the 3.7v i usually run, I ran around 1.1 (sometimes i do constant current, sometimes constant voltage -thats a whole nother topic)...
Anyways, low and behold, the next morning, it was not silver cement fluff but nice beautiful crystals that were staring back up at me. I ended up running the whole lot and didnt have an issue.

After washing the crystals, I dissolved 10 grams in nitric and it left a perfectly clear solution. I was happy. From then on, a breakdown cell became my best friend.


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## saadat68 (Nov 7, 2017)

> I could literally write 50 more paragraphs on it probably, but I am rushing to get a couple things done (and typing this while driving -tisk tisk), so I cannot. But, I can say this -search breakdown cell, search the silver subforum, and read read read it ALL.
> Trust me, it will help you dearly


Thanks 
I will search and read them


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