# cell problems



## buckdec (Aug 26, 2012)

I'm trying to do a similar cell that Steve used for sterling silver with the bowl were you pull the copper out so i thought i would start with just copper and get it to work before i try it with silver. There wasn't much time by the time it was all set up before i had to leave and stop it so it was running for about 30 minutes. so there was no red moss growing on the cathode (graphite) but it does look like it was plated with copper. The electrolyte was 100 ml of 50/50 mix of 70% nitric acid and distilled water with copper then dissolved into it then mixed with 900ml of distilled water. The anode was just some copper pipe that i melted down in a new melting dish with borax. I used a battery charger set at 2 amps on deep cycle and muslin cloth as a filter. now i'm not sure maybe i'm just impatient and its a slow process then i thought or if i have something wrong or maybe it just will not work as this set up. any input would be greatly appreciated.


----------



## Oz (Aug 26, 2012)

Your dilution of your solution meant that the solution was near depleted. You would have been better served to have just used your original 100 ml. If I remember correctly Steve’s silver bowl experiment, it too was done with a concentrated solution.


----------



## MysticColby (Aug 27, 2012)

The electrolyte I use for my silver cell is 100 g silver + 117 ml DI + 117 ml 70% nitric, heated until fully dissolved, then diluted to 1L with DI.
It looks like you used a bit less than half as much nitric. But it will take something like 3 times as much nitric to dissolve the same weight of copper as silver, so your electrolyte would be about 1/6 as concentrated (maybe it only dissolved about 15 g of copper?).
... I've only ever wanted silver out of a cell. for copper, the ideal electrolyte concentration might be very different.


----------



## element47.5 (Aug 27, 2012)

I think you are mixing up two related but entirely different operations. 

Copper will cause silver to drop out of a solution where Ag ions have been mobilized by being in solution. This is "because" copper is a more reactive, less "noble" metal than silver. In the electrolyte you've described, silver will "cement out:, eg; fall out of solution, onto a piece of copper, which will be consumed. No external power is required. The reaction is "powered" by the eletromotive differential between the two metals. This is not what members of this forum refer to as a "silver cell". 

Now you've constructed what looks like a "silver cell" but you're using a "pure" copper anode (what goes or is supposed to go into solution) and trying, what, to plate copper onto copper? I don't get what it is you're trying to achieve. The external power source in the normally constructed silver cell is designed to overcome and move along the "wrong-way" electromotive aspect of silver versus copper, but the cathode (the collector) is graphite or stainless steel. Not copper. It's not supposed to enter into the reaction, it is supposed to furnish a surface. If it was copper, it would just dissolve in the nitric electrolyte until the electrolyte was saturated with Cu. 

In copper purifying cells, my readings indicate that the electrolyte is sulfuric acid, not nitric. 

I guess I really don't get what you are trying to achieve.


----------



## buckdec (Aug 27, 2012)

what im trying to do is run a copper cell but ya i think im running to low concentration of copper nitrate in the end what im trying to accomplish is i have anodes that are around 70%copper and 30% silver and i want to try and run it through a cell so that the silver will stay behind as slime in the filter but thought i would try and get it to function with copper and no silver at first one cause its cheaper and less variables. and yes normally its in a sulpheric acid but i was taking an alteration of what Steve tryed for sterling silver.


----------



## etack (Aug 27, 2012)

What you need to make then is a Cu parting cell. I believe that your feed stock needs to be 95%+ of its desired element to be effective.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=86&t=12205



Eric


----------



## Geo (Aug 27, 2012)

eric is right. and too, i believe copper chloride would be a better electrolyte for copper. ive done some small experiments with both. if you just want the experience, maybe you should use the cheaper material that will do the same job.


----------



## goldsilverpro (Aug 28, 2012)

I see no way you can form a separation and collect the Ag as anode sludge. They both will dissolve in a nitrate system. 

With 70Cu/30Ag, the only possible electrolyte I can see that might work would be CuSO4/H2SO4. Even then, the high Ag might block the dissolving of the Cu or, at least, slow it down considerably. 

Were it me, I would shot the metal, dissolve it in 50/50 nitric, and then cement the Ag on Cu. With proper rinsing of the cement, you might get 99% purity that way. It will take about 3.2ml of 70% nitric (actually 6.4ml of 50/50 nitric) to dissolve a gram of this particular alloy. If you want a higher purity, you can then melt the silver cement and run it through a proper silver cell.


----------



## MysticColby (Aug 28, 2012)

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=86&t=9876

I assumed you were doing something similar. I've read a few attempts at a copper cell. if you search for the right words, you could get some useful results. There was one that used something like a copper cell to deplate silver-plated items...


----------



## Oz (Aug 28, 2012)

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=2868

I believe this is the thread buckdec was referencing.


----------



## buckdec (Aug 28, 2012)

Ya that would be the thread I was looking at and doing large volumes of it with nitric cementation method would use a lot of nitric and make more fume then I am comfortable with at this time


----------



## buckdec (Aug 29, 2012)

So ran out of nitric so stopped that batch for now but got crystal copper sulphate so trying that tonight stuff is dirt cheap compaired to nitric home depo 11$ lbs as root killer. Plates copper (slowly) so now trying with a 30% silver anode and see what happens. Is it suppose to take a really long time or do I have something wrong? Also when running a cell does it need to be monitored or is it ok to leave running on its own for a few hours?


----------



## MysticColby (Aug 29, 2012)

I forget the exact numbers, but silver cells will deposit something like 3 g per Amp per square inch anode per hour. So if you have a 1 square inch anode running at 2 Amp, it would deposit about 6 g per hour. 'square inch anode' means the visible surface area of the anode that faces the cathode.

I have my cell running on low voltage (=low Amp) and check it like 3 times a day to make sure the silver crystals are not getting anywhere near the anode. If it is, I stir it around with a glass rod. When I can no longer push it down to a safe distance, I harvest. Once it's running, it's fairly predictable how much it grows. But keep in mind: as the distance between anode and cathode decreases, the Amps will increase, resulting in faster depositing.


----------



## goldsilverpro (Sep 1, 2012)

MysticColby said:


> I forget the exact numbers, but silver cells will deposit something like 3 g per Amp per square inch anode per hour. So if you have a 1 square inch anode running at 2 Amp, it would deposit about 6 g per hour. 'square inch anode' means the visible surface area of the anode that faces the cathode.
> 
> I have my cell running on low voltage (=low Amp) and check it like 3 times a day to make sure the silver crystals are not getting anywhere near the anode. If it is, I stir it around with a glass rod. When I can no longer push it down to a safe distance, I harvest. Once it's running, it's fairly predictable how much it grows. But keep in mind: as the distance between anode and cathode decreases, the Amps will increase, resulting in faster depositing.



At 100% cathode efficiency, silver deposits at the maximum rate of 4.025g per amp per hour. However, 100% efficiency is almost impossible to achieve unless you have perfect conditions. The surface area of the anode has nothing to do with it, since the silver deposits from the solution and not the anode.

However, if you did have 1 square inch of anode area running at 2A, that would be an anode current density of 288A/square foot (ASF), which is way too high - ideally, the current density should be between 25-50 ASF. If you ran at 288 ASF, the anode efficiency (rate of dissolving) would be much lower than 100%. In that case, the silver would deposit at the cathode much faster than it would dissolve at the anode and the silver in the solution would quickly be depleted.


----------



## MysticColby (Sep 4, 2012)

huh. I haven't heard that bit of wisdom until now, thanks.
I wonder what's going on in my setup.
at 3.3V, it can sometimes be as high as 2.5A. I prefer lower voltages (1V results in about 0.75A) because it seems to grow thick crystals, whereas 2-3V grow fast thread-like crystals. I've never seen anything to suggest the solution's depleted... but it is closer to 2.25 square inches of anode area.


----------

