# Copper Nitrate Cell



## rusty (Apr 18, 2011)

The new cell I'm working on uses copper nitrate for the electrolyte, the anode made from copper alloyed with precious metals such as gold and silver with perhaps a bit of the platinum group.

About the cell, there is a porous membrane divider, the book says they used asbestos rock sheet for the membrane, I'm going to use unglazed tile called quarry tile for the membrane.

The cathode side uses copper sheet, I do not have nor wish to spend money for this, so what I plan on doing is setting up a board with removable pegs that I can weave a copper mesh from wire as my collector. I believe that as the cell deposits copper onto the mesh the small holes will eventually fill giving me pure copper.

From the anode side any silver that is alloyed in the copper anode will go into the copper nitrate solution, every so often the liquor is harvested, the silver is cemented down using copper. The barren liquor is returned to the cell where the copper will be deposited onto the cathode.

Precious metals from the anode settle as slimes in this side to the cell to be further refined. Voltage is the cell is not to exceed 1.5 volts at 20 amps per square ft of anode. However this is in theory, I may be proven wrong as this project moves along.

On a side note, I do not think using a battery charger will give suitable results, the higher voltages will give a mossy deposit at the cathode with possible co-deposit of other metals.

Regards
Rusty


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## seawolf (Apr 18, 2011)

Rusty can you post a few pics of the cell?
Mark


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## HAuCl4 (Apr 18, 2011)

Great idea!. I'm interested in the type of membranes that you plan to use. 8)


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## qst42know (Apr 18, 2011)

Isn't copper usually refined to a solid deposit in a copper sulfate electrolyte?


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## lazersteve (Apr 18, 2011)

Gill,

I'll donate a section of copper mesh to your project.

PM me for details.

Steve


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## rusty (Apr 18, 2011)

lazersteve said:


> Gill,
> 
> I'll donate a section of copper mesh to your project.
> 
> ...



That would be great Steve, but I think that we should wait until the jury is in, perhaps Chris could give some advice regarding the pros and cons of using mesh over solid copper sheet for the cathode.

I'm thinking that the weave would not have to be all that tight with maybe holes as large 1/4" in the mesh made from freshly stripped copper wire, the cell based on Quarry Sheet will be 12" by 12" each compartment, the actual box a bit higher to allow for excess electrolyte as the anode is lowered into the cell.

The cathode should be of the same size, I've been toying with the idea of a revolving cathode which would give a nice even deposit all around. Due to the weight that will eventually collect onto the cathode I do not think this plan is going to take root. 

My furnace and crucibles are still over at the other house, so melting anodes is still a ways off, and this new shop is just now coming into shape. Missed the lumber yard today but did purchase my T5 lights in 8 footers at $85.00 each from another shop.

Getting stuck with the truck killed a lot of time, then the Quad got stuck high centered on the snow and be damned of I could find reveres. Anyhow it was a fun day supper was on the warmer when I got home and the dog finally ate his supper. Yea the dog won't eat unless I'm home. wife says that I should take him with.

I would but the dumb dog cant see the window glass and he gets dog snot all over the windows and I get tired of cleaning the windows when I have to take the wife with me.

Before I derail this thread entirely, I'm very excited and anxious to try out the copper nitrate electrolyte cell.

Regards
Rusty


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## Militoy (Apr 19, 2011)

I'll be following this new thread with interest. I have NO experience with electrochemistry - but we do design and build power supplies that are used by some of our customers for that purpose, as well as for cathodic protection of pipelines and shipboard cooling systems. I actually have several "DC rectifiers" (power supplies) designed specifically for electroplating in my scrounge junk pile. I'm also lucky enough to have a chemist working (out of his field) with me - whose brain I can occasionaly pick! I'm a newbee at applying chemicals to my own gold - but I might also eventually find it interesting to apply a bit of controlled electrical current to the equation.


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## nickvc (Apr 19, 2011)

Gill I tried the same sort of thing some time back using the ceramic outer from a crucible from an induction casting machine as the membrane. The problem I encountered was that as I was warned by Harold and GSP floating gunk and a poor deposit after a fairly short period of time. I think that you must have a high % of copper and a very low % of precious metals, something over 98% copper is where I'd start if I tried again, if I remember correctly I was around the 93% copper. There's plenty of information about copper refining available so I'd check on the feedstock they use and try to be slightly higher in the % of copper in yours.
I love your imagination when it comes to finding a method and creating the machinery to recover and refine your metals and wish you luck in this latest trial.


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## Oz (Apr 19, 2011)

I would agree with Nick’s statement as to the purity of the anodes. While I have never built a copper electrowinning cell before, I have done a fair bit with silver cells. I have found that anything over 3% insoluble elements such as Pt or Au in my silver anodes gives me grief. 

The insoluble elements form a crust that is adherent and all but stops the dissolution of your main metal. The crust is conductive however, so it behaves as an inert anode causing you to deplete your electrolyte. That changes your cell parameters around such as the conductivity of your electrolyte which can in turn change voltage and amps depending on your power supply. The depletion of copper in this case could also allow other elements to plate out that normally would not, the character of your deposit (smooth, rough, nodules, or needles) will change as well.

I would suggest you start with a pure copper anode in the beginning in order to figure out your cell design. After everything works to your satisfaction, then start trying to incorporate copper anodes with low grade values until you find the practical limit. This way you know your cell is fine, but it is the anodes you are running when you have troubles.


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## rusty (Apr 19, 2011)

Good advice Gentleman, you may recall that earlier on in the forum I did a melt from some milled IC's that I cast into rounds, if memory serves me I ended up with a tad under 12 lbs of copper alloyed with various metals which I never did recover successfully due to being a dumb ass by not testing with stannous before you jump on me I made my confession and apologies to Harold_V a very long time ago as he had spent considerable time tutoring me privately and I owed him that much.

All my feedstock is low grade having come from electronic scrap, with proper fluxing during the melt the anode is partially prepared, if the cell proves out I would like to try various anodes were I have added silver contacts, then try some catalytic material, not sure if the copper will pick up rhodium which I'm to understand is now an oxide.

Then my mind rushes forward thinking that some cats are sent to a copper refinery for reclaiming the precious metals within.

At this point in time, it looks like I have an exciting year ahead of me experimenting with the cell, on another front a spin off from refining precious metals I have decided to revisit an old hobby - photography. I have purchased several books on how to use platinum. palladium and gold to make contact prints.

You would be surprised at how close refining and photography are actually related. If you have someone in your neighborhood practicing alternative photography this would be another source of precious metals scraps as most do not have the knowledge to reclaim spent metals from crops and spoiled prints. 

Since I will have very little to add to this thread for the moment, will let you gentleman toss some ideas around while I busy myself getting prepared to further my work on this project. 

Regards
Rusty


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## rusty (Apr 19, 2011)

Oz said:


> I would agree with Nick’s statement as to the purity of the anodes. While I have never built a copper electrowinning cell before, I have done a fair bit with silver cells. I have found that anything over 3% insoluble elements such as Pt or Au in my silver anodes gives me grief.
> 
> The insoluble elements form a crust that is adherent and all but stops the dissolution of your main metal. The crust is conductive however, so it behaves as an inert anode causing you to deplete your electrolyte. That changes your cell parameters around such as the conductivity of your electrolyte which can in turn change voltage and amps depending on your power supply. The depletion of copper in this case could also allow other elements to plate out that normally would not, the character of your deposit (smooth, rough, nodules, or needles) will change as well.
> 
> I would suggest you start with a pure copper anode in the beginning in order to figure out your cell design. After everything works to your satisfaction, then start trying to incorporate copper anodes with low grade values until you find the practical limit. This way you know your cell is fine, but it is the anodes you are running when you have troubles.



Oz I understand the complexity of the silver cell and how finicky the electrolyte can become with the depletion of silver, the copper nitrate cell is always replenishing copper to the electrolyte as it's being plated out, the silver is harvested from the liquor is reported to be .995 making this material a suitable candidate for the silver cell.

If the cell works as well as I'm hoping, silver contacts would be much better processed from a cell of this design as any palladium and gold will report as slimes, rather than gallons of waste liquids that have to be treated with cementing with aluminum or iron before disposal.

I have many pails with slims on the bottom, which I'm almost positive contain more than copper due to my lack of knowledge for a total recovery. Hoke refers to these wasts as the stock pot, we all have these pails, so I figure why not add the slims to the anode melt.

We have always been advised to incinerate, and we know fluxing can remove a lot of unwanted junk so we have killed two birds with one stone, tin is the only metal I have found that incineration will not effectively remove. After treatment with HCL this should be another good candidate for a chlorate cell to recover the tin which we all value for making up stannous.

All too often gold and silver are found in nature alloyed with copper, from were it is recovered using EMF ( electromotive force ) then moving along to wet chemistry to refine the cell slimes.

Regards
Rusty


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## rusty (Apr 19, 2011)

Casting an anode requires that you have a furnace of some sort along with some accessories. There is tons of information available from the backyard metal casting forum and how to build a foundry furnace with formulas to make DIY refractory for those of you who have that independent streak often referred to as being bone headed and stubborn.

A simple furnace can be constructed using firebrick piled atop one another, you do not even have to cement them together. This was my first furnace used to melt and make my first aluminum casting for a vibratory flat lap used for lapidary work. The furnace was fired using a tiger torch.

I've never attempted to make my own refractory so I am not able to give any pro or cons, the current furnace I have was made using a castible refractory which maybe cost me a couple of hundred bucks to construct with maybe 4 hours of my time. The furnace has served me for over 5 years, now that I plan on heavy fluxing of my melts it's a given that the flux will take a heavy toll on the refractory.

To make the furnace I poured the floor first let this set overnight, then used a plastic garbage pail which I inserted dead center, filled to can with sand and cut in my blower hole in the outer metal shell which I then put in a suitable plastic pipe before pouring the rest of the refractory. During the pour gently tapping on the metal shell to help settle the refractory it;s the same as if you were working with cement doing a foundation.

The lid is made from a metal shell, I drilled holes around the perimeter, then inserted large spikes to hold the refractory in place once dried, welded a couple of grabs onto the top to make lifting easy. Some guys make the furnace so that the top half tilts away or a front load. I use a pneumatic chain hoist to do the lifting, the hoist is on an overhead rail so getting the lid out of the way is a simple task. 

The hoist was not purchased specifically for this task, it just one of those gotta have things.

I frown on anyone suggesting the use of crucible made from metal, metals when heated to extreme heats are solvents which will leach into your melt. Use clay or clay graphite combination mix's or silicon carbide crucibles.

Always assure that your metals are free of moisture before adding them into a melt, moist metals have a tendency to cause steam explosions which can splatter hot molten metal on your body. I lay additional metal needed for a melt onto the furnace lid for pre-heating and to get rid of any possible moisture.

My copper melts are poured into an old cast iron frying pan, gives nice rounds that release from the mold with out any difficulties.

Little Johnny not to bright in school the teacher had sent many notes home with the lad for a parent teacher with the father who ignored the requests, the teacher having some spare time on his calender paid the old man a visit.

The old man a Blacksmith asked the teacher to hand him a piece iron fresh from the forge, well you should have seen him hoot and hope when he picked it up, now the old man gives whistle and Johnny comes a running in and says yes paw. The old man asks the kid to hand him the same iron the teacher had dropped, well Little Johnny goes over and spits on the iron, goes over and grabs a set of tongs to hand the old man the hot iron. Old man looks at teacher and says see Johnny ain't so dumb.

If you need further instructions on furnace building or fuels to fire it with go to backyard metal casting.

Regards
Rusty


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## HAuCl4 (Apr 19, 2011)

Same process but basically changing the steps a little:

1-Dissolve the alloy in nitric acid. Filter to recover any slimes.
2-Cement any possible palladium, platinum, gold using a super simple specially built iterative filter with silver or sterling silver as filtering medium(see below).
3-Cement the silver using a similar iterative filter with copper as filtering medium.
4-Once every noble metal is out of solution (test with stannous), put the liquid in your copper cell to recover the copper and the nitric, which can perhaps run unattended 24-7.

A couple of iterations of the liquid through the filter at a reasonable speed cements the target metals usually.


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## Irons (Apr 19, 2011)

I have some Copper on Glass Epoxy circuit Board material if you're interested. I have single and double-sided in 4, 8, 16 mil core thickness. It makes great Cathodes.


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## rusty (Apr 19, 2011)

I would like to extend my thanks to both Steve and Irons for their generous offers., however the cathodes will not pose a problem. I have a couple of the old copper wash tubs, I think they are called boilers that I can cut up for sheet copper.

The biggest hurdle I've come to is finding a 12' x '12 unglazed tile, the best I could find this afternoon after calling on several tile shops is these 6" x 6" tiles. I thick that they will do for a test cell, to make them leak proof I'll caulk them with butyl rubber that black sticky stuff they use to install windshields in cars and trucks.

Its cell is slowly coming together, but that truck load of building material is going to take priority one over all else.

Regards
Rusty


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## Oz (Apr 20, 2011)

rusty said:


> Its cell is slowly coming together, but that truck load of building material is going to take priority one over all else.


I could not help but notice all the insulation in that load. I would imagine where you live there is no such thing as too much insulation.


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## Toobigfortx (Apr 20, 2011)

I was just thinking, Seeing as how the width of the copper is unimportant but the acual square inch size is why not try a piece of .999 copper foil the roles are cheap on ebay. Oh and I have heard that using a steel plate, after u've removed the copper, will collect the silver, But IDK how true that is. I've always been extremely interested in this. If you get it up and running please let us know.


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## Toobigfortx (Apr 22, 2011)

I just read something about a copper refining plant In Chile that uses ammonia to desolve copper instead of sulfuric acid. I dont know if this helps you at all but supposedly it was WAY more cost effective than the sulfuric acid method


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## samuel-a (Apr 22, 2011)

It will be interesting to hear (and see) your results.
Tough, a few points of concern comes to mind with your cell plans.

The anode compartment will need free nitric at all times to be able absorb silver with the copper... i can't imagine a silver metal (or Pd) giving up it's electron in a saturated copper solution....
given there is a free nitric in the electrolyte, i can't see why Pd won't be dissolved as well.
Then there's the loss of nitric during cementation process (NOx evolution).

What will be the end result of the depleted electrolyte at the cathode side? rejuvenated nitric?

i think you should also count in the voltage/current drop duo to the membrane.

And a Q for the pro's, does a membrane can hold enough negative potential (even though it's neutral) to actually reduce metal on it's surface ??


humm.. that's it, I'm done bugging you :mrgreen:


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## peter i (May 17, 2011)

As far as I know, the commercial refiners of copper do not use membranes.

The alternate the plates in large tanks using several hundred amps per square meter, lifting out the cathodes on regular intervals to scrape of the purified copper. (the electrolyte is copper sulphate kept acidic with sulphuric acid)
The slime is collected from the bottom of the tank.

Somewhere I have a very nice description of the process used at Boliden.


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## rusty (May 17, 2011)

HAuCl4 said:


> Great idea!. I'm interested in the type of membranes that you plan to use. 8)



I managed to get some asbestos sheet from the farm, but it is much thicker that I had remembered it, some other thoughts are to use unglazed tile, sold as quarry tile. Then there are large sheets of fire brick that comes in tile used in fireplaces.

Also there is a square liner used inside old brick chimneys, a person could cut one side off to use, this is unglazed but again on the thick side, some old houses has asbestos tiles affixed to the outside walls. I was fortunate to find some of these at the dump a week ago. These tiles are usually painted one side an they are on the thin side.

I'm aware of the health hazards of cutting asbestos and so should you, cutting should be done wet to keep dust and fiber to a minimum and wear appropriate breathing gear. It looks like the discarded house tiles are going to be a first choice to use as a membrane.

I read another article on another copper nitrate electrolyte cell and they do not use any membrane in the cell. A point of interest is that the cathode is made narrower than the anode to allow for the growth of copper.

Regards
Rusty


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## Harold_V (May 18, 2011)

rusty said:


> It looks like the discarded house tiles are going to be a first choice to use as a membrane.


I have not followed this thread intimately, so my comment may not be valid. That being said, you may have to review your decision on using house tiles. If memory serves, they are made of Transite, which is bonded with Portland cement, and readily breaks down in the presence of acid. 

Harold


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## seawolf (May 18, 2011)

What about using a polypropylene anode bag to catch the slimes or a polypropylene divider as a membrane?
Mark


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## rusty (May 18, 2011)

Harold_V said:


> rusty said:
> 
> 
> > It looks like the discarded house tiles are going to be a first choice to use as a membrane.
> ...



Thanks Harold for the information on Transite, it appears that all the asbestos board I have is of the same material made of asbestos fiber bonded with Portland Cement. And this would include the chimney tiles, so I can scrap that idea.
http://en.wikipedia.org/wiki/Transite

seawolf, yes an anode bag wold work. I'm trying to replicate an old cell design, which was made from wood and asbestos board just for kicks.

Regards
Rusty


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## qst42know (May 18, 2011)

I haven't shopped around (price wise) but asbestos is still available as well as close substitutes.

http://www.caztex.net/products.php/12-Dust_free_Asbestos_Cloth.html


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## aflacglobal (May 18, 2011)

Do you know what the pore size of the membrane is you’re looking for?


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## rusty (May 18, 2011)

aflacglobal said:


> Do you know what the pore size of the membrane is you’re looking for?



Unfortunately not, these old books only generalize on procedure. That is one problem with book learning you still have to get your hands dirty to fine tune the construction of the cell and play with the electrolyte, temperature and voltage to get it right.

I should have my furnace over here at this new shop sometime this upcoming week, then I plan to make anodes to experiment with. Using a large telegraph glass battery case as my cell will get this project started..

The disadvantage of using an undivided cell is that silver and palladium will pollute all the electrolyte making harvesting a bit more work, in the divided cell you only have to remove the electrolyte from the anode side of the cell which you then cement the values out with scrap copper returning the barren solution back into the cell to further reclaim the copper. You must add a bit of free nitric from time to time to the electrolyte.

Should be a fun experiment.

Regards
Rusty


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## rusty (May 21, 2011)

The furnace and crucibles are at the new shop, the first melt shall consist of the copper from microwave magnetron's. I'm hoping to find some gold alloyed with the silver solder from the older ovens.

The washer and copper bolts came from a large Delco tractor starter, I was surprised to see that the washer is silver plated and the bolts have a silver wafer soldered on the tops.

Advantage if using the cell, silver from electroplate can be easily recovered, plus no more wasted silver left behind from sweating the contacts off.

Regards
Rusty


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## peter i (May 24, 2011)

there is an old thread about copper refining at Boliden:



peter i said:


> http://www.springerlink.com/content/n08u41072184506w/fulltext.pdf
> 
> A nice description of an industrial set-up mainly working from copper ore, to pure copper and anode slime, to pure silver and another slime, to pure gold.
> (45 kilo anodes... now we're talking silver-cell!)


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## Juan Manuel Arcos Frank (May 25, 2011)

Rusty:

Try to use a salt bridge,with it solutions will not mix and you can get silver(and gold and PGM) in one half cell and copper in the other half cell.I am posting for you an old book about copper:

http://www.archive.org/details/metallurgyofcopp030250mbp

I hope it helps.

Keep us posted about your progress.

Kindest regards.

Manuel


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## rusty (May 25, 2011)

Juan Manuel Arcos Frank said:


> Rusty:
> 
> Try to use a salt bridge,with it solutions will not mix and you can get silver(and gold and PGM) in one half cell and copper in the other half cell.I am posting for you an old book about copper:
> 
> ...



Thank you very much Manual for the link to the copper metallurgy book, it is much newer than the ones I have on hand. I will be sure to look up information on the salt bridge.

Below is another sample of the material I want to recover the silver from.

Best Regards
Rusty


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## rusty (Feb 18, 2012)

peter i said:


> there is an old thread about copper refining at Boliden:
> 
> 
> 
> ...



Thanks Peter, I have downloaded the article, and have now begun the task of reading.

The composition of their cell slimes differ from mine but I have found some very interesting information on the first few pages explaining some of the bad things that happened with my copper sulphate electrolyte cell.

The link offers a purchased article, not sure of it's legal to redistribute so to be on the safe side will not repost it.


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## martyn111 (Feb 18, 2012)

Out of interest Rusty, do you think that an unglazed flower pot would work in the cell you are building? The walls of the flower pot should be thinner than unglazed quarry tiles and apart from blocking the drainage hole in the bottom of the pot, the construction would be much easier than attempting to construct a box using tiles.


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## Geo (Feb 19, 2012)

you can get the clay pots without the hole. we have a place called The Pottery Barn here and they have about anything you can think of in clay.


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## rusty (Feb 19, 2012)

Geo said:


> you can get the clay pots without the hole. we have a place called The Pottery Barn here and they have about anything you can think of in clay.



The clay pot would be perfect, but I'm in Canada with few gardening options living in the country everyone plants in the ground our city dwellers use plastic plants in plastic pots to set in the windows or front porch.


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## martyn111 (Feb 19, 2012)

Thanks for your replies Rusty and Geo, I'm not so much thinking of using the cell for refining copper but I am thinking of maybe using a similar set up for a silver refining cell, do you think this would be viable, will the silver pass through the clay (membrane)?


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## Geo (Feb 19, 2012)

it may be a good idea to put it in a plastic bag too. NoIdea had a thread about this. he pyrolized the whole board and melted the metal into anodes parting the copper first with the slimes being, well, everything else.


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## rusty (Feb 19, 2012)

martyn111 said:


> Thanks for your replies Rusty and Geo, I'm not so much thinking of using the cell for refining copper but I am thinking of maybe using a similar set up for a silver refining cell, do you think this would be viable, will the silver pass through the clay (membrane)?




It should work, but for some reason an anode bag is preferred for silver anodes. I think it is because you can incinerate the bag to recover all the values.


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## martyn111 (Feb 19, 2012)

Thanks for your input Geo, I will do a search for that thread and study it.
What you have just said has lit a light bulb, the method Patnor used to refine black chips, all the metalics from within the chips could be melted into anodes and refined in this manner, removing the copper first and then treating the slimes.


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## rusty (Feb 19, 2012)

Scrap copper is used as a collector of precious metals the end result is refined copper with precious metals in the cell slimes where they can be further refined.

When I made my copper anodes I added copper with silver soldered connections plus the metallics from some IC's that I had incinerated then milled then processed the anodes in a copper sulphate cell.

What I have now is silver slimes co mixed with other precious metals, almost ready to run in a silver cell, which will then leave me with the gold and platinum group as slimes for further processing.

In the next round I plan on using the copper nitrate as my electrolyte keeping some free nitric available, slightly different procedure with the same end results.


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## jonn (Mar 12, 2012)

I wonder about the voltage you are using. According to the research I have done, copper has an electrochemical potential of .34 and silver is .7. You said you use no more than 1.5 volts. Wouldn't that plate your silver out as well? I'm running 2 cells currently and my anode refining cell is at .4 volts and my winning cell cell is at 1.5. The winning cell is removing all metals within the range of 1.5 and lower. The nitric should in theory be able to be reused. There should also in theory be no gold or pgms as this is nitric solution only. Please be aware this is posed as a question only as this is my first run. Any corrections to my formulas would be greatly appreciated. Is my refining voltage too low? My blister copper contains all metal with rhodium as well. There is a nice layer of black powder on the bottom but my cell has been running for 3 weeks now and the anode is only slightly smaller. My cathode was made from wires and is now more than 1/2" thick. The cathode looks real purdy, when inspected under light it looks like bright and shiny copper with no trace of impurities.any thoughts would be appreciated as the the correct voltage to use. I am currently using 2 calibrated rectifiers built for this purpose. The voltage stays the same, always, but the amperage seems to increase as my cathode gets larger. According to my calcs, it should about 1 month per lb. Of blister copper. Like said, it has been 3 weeks and the cathode looks about the weight of 1 lb or more now. By the way, the amperage according to the digital meter started at .15 and is now up to .21 Thank you all for this awesome site and any clarifications or corrections in advance. Cheers.


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## butcher (Mar 17, 2012)

John the reduction copper in the half cell as i understand it when gaining an electron is 0.34 volt, but also would you not also have the copper anode oxidation voltage to consider, bringing up the voltage requirements of the cell, and as I understand it, it is the current that is important in determining how much copper is transferred from anode to the cathode in the cell, and surface are will play a big part in that figure.

What happens if you increase the current your running the cell?

It sounds like your getting a good solid plate of copper, if so this may be a way for us to sell our copper waste, if making the copper powder we generated into anodes was not too costly to melt.

Using copper nitrate waste in a copper cell and then possibly making nitric acid out of the copper nitrate solution when your finished with the project does sound like a good idea.

Laser Steve had a post about using graphite to remove copper from the copper nitrate solution, and then use the nitric in an silver cell.

John is there any way you could post a picture of the cell?

How did that purple powder come out, I do not think we ever heard the rest of the story on that project.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=6361


I have been up too many hours my mind fell asleep but my finger are still typing, good night, let us know some more about this project.


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## jonn (Mar 18, 2012)

Hi butcher, the purple powder was gold as you mentioned, it turned out great. If memory serves, it was about 5 grams or so. I use your process on all my reclaimed powders know with exceptional results. Thank you very much for the thorough explanation. On the cells, I would love to post photos but dont know how yet. Can you help? The winning cell is working great, and no you don't need to remelt the copper for sale purposes. I am using sheet as cathodes that I ran through my rolling mill. The thickness is about 1/16" and 2" wide and 14" long. That's what I start with. The anode is superfine carbon graphite bar 3/4" thick and 4" wide and 14" long. BTW, I have tons of graphite, Anyone please PM me if interested. The cathode deposit is ultra fine copper crystal and my cathode after winning my first batch is now about 1/2" thick. No legs or stragglers. Just an increased thickness of my cathode. I could roll it through the mill and continuously accumulate pure copper that way. The voltage on this machine is higher than my refining cell. Voltage at the anode was a question you asked,that would be the refining cell of course. I assume the voltage is still .34 at both the anode and cathode. It seems to doing a great job although it's awful slow :x my goal is to run a series of 8 cells at the same time. It would take about 3 months and after completion I would need to replace the blister anodes. The sludge would be collected and refined and hopefully by combining all the sludge from the 8 cells, I would have a pretty good yield of PM's. :lol: 
The electrolyte would of course be reused until completely spoiled by solubles. I am hoping to get at least 3 runs out of it. Once pregnant, the nickel and other solubles would be dropped. Not sure which method would use yet. I'm thinking I may be able to run this material through the winning cell but still need to do more research.thanks butcher, you are as always a great help.Jonn


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## jonn (Mar 18, 2012)

Hi butcher, sorry I misunderstood when you said if the copper powder is not too expensive to melt into anodes. I don't melt copper only into anodes. I selectively add gold and silver when I first cast the anodes to insure there is at least 97% copper. I plan on refining my silver and gold after the copper is removed, therefore eliminating a step. I don't need to boil in nitric first to eliminate copper. The cell does that for me. As for the reduction potential of the anode, the nitric actually reduces the anode, not the electricity. My electrolyte is at first saturated with copper, with a blister copper anode. The cathode and current cleans up the electrolyte a bit until there is Free nitric. The free nitric dissolves the copper blister anode. The Current deposits clean copper onto the cathode. The sludge falls and is collected once the anode is gone. The sludge is then refine with a minimum amount of acids. All in theory of course as this is my first run.
By the way, I removed the winning cell cathode grid this morning, it was almost 5/8" thick. I sent the cleaned electrolyte over to my finger dissolution bucket and added more pregnant copper electrolyte to my grid. Fingers are the only thing I boil in nitric. And that is my cell electrolyte. 

From what I gather on from this forum, most folks boil in nitric first to remove impurities. I'm trying to replace that process with the electrorefining cell. I used to also boil in nitric first, but have accumulated too much solution. That is the reason im trying this way. Another bonus is that the cell puts off a bit of heat and some electrolyte evaporates. I simply add more from my stock pile and hope to reduce my volume and increase the strength at the same time. I hope it works. :roll: we will see.


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## butcher (Mar 18, 2012)

Jonn, 
Since your electrolyte is fairly clean, copper nitrate used only on fingers, and your copper if fairly pure, may be the reason for the tight grain, and not the loose fluffy copper powder I have seen, the way I understand the current and surface area have a lot to do with how much copper moves from anode through solution to cathode, maybe increasing surface are of the cells, and running higher current, might speed things up some?

Are you sure you will not also have to figure in anode oxidation voltage?

I am not very good with computers, and a friend showed me how to post a picture, I done it then, but I am unsure if I can do it now, I will try here, with how I am doing it:

Reply to post to bring this page to type into.
At top of this page there are a bunch of boxes with funny letters and symbols.
Click on the box Img.
It puts two img on page with the curser between blinking.

Below you will see a square box Browse, click on it.
It will allow you to pick a picture out of your computer (you may have to find the file you have the picture in like my pictures), pick the picture, can also type in a note, in box below and click add the file.

If the picture shows up I still can do it, if not we both need help.


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## jonn (Mar 18, 2012)

Hi butcher, your picture showed up so I will also try to load photos. Yes the current and surface area have a lot to do with the speed of plating, I agree with that. As mine cathode grows in size the amperage increases which in turn hastens deposition. My voltage stays the same though. If I were to increase the voltage, the amps would also increase. But my deposit would be loose and fluffy, ( tried it). my machine controls voltage only and the amperage is automatically set by the surface area of the cathode. This is only my opinion so far but since the machines are digital and calibrated and built for plating I assume this to be correct. If I put the electrodes closer together my amperage would increase. If I use larger electrodes my amperage should increase. I am 4" apart now and fear that if I get any closer they may grow a crystal and short out the unit.your photo shows 2 cells, I am using only one with copper nitrate as the electrolyte. I definitely need to study more on this subject, that's for sure. Is that a salt bridge in between two cells? Would it plate both copper and iron at the same time? Looks like a good idea. I guess I still have a lot of reading to do.  I will study further and report back. In the meantime let's see if I can snap photos and upload. Thanks again butcher , helpful as always and much appreciated. Jonn


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## Geo (Mar 18, 2012)

i am far from "in the know" about the cell and its operation but in my experience heat also factors in the amperage usage. cold electrolyte tends to use less amps than heated.this is not a fact, more like an observation on my part.


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## jonn (Mar 20, 2012)

That makes a lot of sense Geo. I believe you are correct. Heat is energy. I hope I can keep my cells cool enough for safety reasons and also power consumption. I can't seem to get my photos to load. Maybe it's because I'm using a iPad. I wonder if theres an app. for that??


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## butcher (Mar 20, 2012)

Electrolytic cells (plating cells or electro winning cells), and galvanic cells (voltaic cells) are very different, although they have similarities as well.

An electrolytic cell is like your refining cell using an external power source, (or a battery being charge by an external power source).

The galvanic or voltaic cell is the battery being discharged, like when using the battery to light a bulb.

Let us discuss a battery for a bit.

A battery can act as both of these, depending if it is discharging or charging,

In a battery (voltaic or galvanic cell), it can be somewhat confusing as polarity of the cell is reversed during discharge and charging conditions.
Cathode is an electrode that, in effect, oxidizes the anode, or absorbs the electrons.
During discharge, the positive electrode of the voltaic cell (battery) is the cathode.
When charging, that reverses and the negative electrode of the cell is the cathode.

Basically when,
Discharging the battery the cathode is the positive terminal, and the anode is the negative terminal.
When charging the (the battery becomes an electrolytic cell in a sense), 
And the above reverses,
Cathode it’s the negative terminal and the anode is the positive terminal.


The battery, is just two dissimilar metals in an electrolyte (either acidic or caustic solution), the battery discharging the chemical reaction produces an electric current, and the chemical energy makes an electrical energy we can use, and when being charged the external electrical current applied from the charger is converted to chemical energy within our battery, so our induced electrical current results in a chemical reaction.

Negative terminal
When the battery is discharging the electrons are released at the negative terminal (Anode).
And when the battery is being charged Cations receives electrons from the cathode (negative terminal).

Positive terminal 
When the battery is discharging, here the electrons are received by the positive terminal (cathode).
When the battery is being charged Anions release electrons to the Anode (positive terminal).


In essence you’re plating or electro-winning cell is very much just like the battery that being charged with an external source.


Edit to add:
I have always called the positive of a battery teminal the anode, this makes this discussion on batterys even more confusing for me when thinking of charging and discharging the cells of a battery.


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## jonn (Mar 24, 2012)

Thank you Butcher,that explains a lot. I must admit I'm a bit stubborn though. In spite of being told to turn up the voltage on refining cell, I did not. I have it running at .4 and went to inspect on it this evening. WOW, what a shock.....
I lifted my grid out of the electrolyte and was a bit upset to see that my anode has retained it's shape and size. My cathode has grown to over 1" in thickness. So I did what any curious cat would do, I touched the anode and boy was I surprised. It crumbled. It appears that if I shook it or disturbed it in any way, it would simply and completely fall apart. I have decided to get some rest now and look at it in the morning. My plan is to let it run again overnight and remove it tomorrow. I will place the anode over a tall form beaker and poke at it with a skewer made of glass. I am quite curious to see if there is any copper left in the core. The anode is multi colored in the crumbled side wall where I touched it . The colors observed were brown, grey, and black with spots of blood red. I am assuming the blood red is Iron (FE). I will post results after I poke at the anode tomorrow. Thanks.


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## jonn (Mar 26, 2012)

Ok, so I removed the anode and placed it over a tall form beaker. I poked at it with a glass rod and was able to remove about 1/4" of sludge all the way around. I squirted the anode with water and exposed fresh copper which appeared to be etched or lightly sand blasted. I set the grid back into the electrolyte to complete the process. I'm thinking it may be another month or so until it is completely refined. I may have to remove the sludge again possibly. This was done 2 days ago and the blister anode is once again changing color to grey/ black. Will keep posting as I progress. Thank you.


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## jonn (Mar 29, 2012)

Hi Butcher. I've been doing more research on the electrorefining of copper and found a book that says: the voltage of copper at the cathode for deposition is +.34 volts and the voltage at the anode to strip is -.34 volts, in theory the cell can run at 0 volts. That's not going to give any current or account for any losses, so the cell should be set to .34 volts. That gives a pure and clean deposit. My cell is set at .40 . Free nitric should be in the range of 10%. my deposit is slow to be certain but my cathode is super bright and hard without any loose powder or impurities. I bought the book. It's quite interesting.it is ; The handbook on material and energy balance calculations in material processing. That's the title. It's some technical reading, almost like learning another language. But very worthwhile  do you know if running multiple electrodes changes anything as far as the rate of deposit?? If my cell is running 3 electrodes and shows a proper voltage and current, would that be 3 times faster in mole transfer or simply faster because of quantity? Anyone please feel free to comment as I'm always open to learning. I did start another cell with 3 anodes and four cathodes placed in circular fashion. 3 anodes in a circle with 3 cathodes in between and one cathode dead center. This is my second refining cell and I will post results. Thank you.


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## butcher (Mar 29, 2012)

I would think oxidation and reduction would total 0.68 volts, this will also not count for resistance of the cell the power supply would have to overcome, so I would try around 1.5 volts and see how it worked you can make adjustments as needed.

The larger surface area (or multiple electrodes), would increase production from surface area, you would also most likely see a higher current draw from your power supply, (less cell resistance also I would expect).

This is not from experience just my theory, your results may differ.


Look again at the cells in the picture above the one on the right side, notice the voltages add up to .78 volts needed from the battery to dissolve the anode (into solution and plate onto cathode (from solution), (the picture represents a divided cell with a salt bridge but the principle is the same).


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## jonn (Apr 1, 2012)

Hi Butcher, you are correct. The plating voltage for FE is -.44 and copper de-plate is -.34 which equals a negative -.78

In the galvanic cell the de-plating of FE is a positive +.44 and the plating onto copper is a positive +.34 which is a cell potential of positive +.78

Now, to deplate copper, as in your diagram, you need a negative -.34 volts....
To plate copper, as in your diagram, you need a positive +.34 volts 
A quick math question? What is -.34 + +.34 ? Is it not zero?

My second cell is now running at .2 volts and it is actually plating quicker. This is the one with 3 anodes and four cathodes. I initially started it out at .4 but the deposits were loose and falling of the cathodes.
My second cell also has a higher amperage. So, I turned the voltage down, which decreased the amperage to the same amperage as my first cell. I am now getting a strong deposit.

By the way, the formation of hydrogen is commenced at 1.8 volts. I would strongly recommend for anyone to NEVER run a cell at or above 1.8. Hydrogen in the presence of Oxygen is immediately EXPLOSIVE.
Its the formula NASA uses for their shuttles. If that can propel a shuttle into space, I'm certain it could also propel a garage or lab into your neighbors yard or far beyond  

So, is my math correct? Please advise.... Thank you.


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## butcher (Apr 1, 2012)

Notice in this document they use about 2 volts to electrolyticly refine copper.
http://electrochem.cwru.edu/encycl/art-m02-metals.htm

Here around 2 to 2.3 volts.
http://www.saimm.co.za/Journal/v109n06p343.pdf

I ain’t no math wiz, (-0.34) + (+0.34) = 0.68 volts, but you have much more you need to consider, the cells resistance to this voltage, look up cells over potential.

It is when the current is too high that you gas off hydrogen (splitting water in the cell).

Current can be regulated, I use an old truck head lamp in series with the cell.


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## butcher (Apr 1, 2012)

http://www.uctm.edu/departments/MCMT/BG/E-library/Extractive_Metallurgy_of_Copper_-_G._W._DAVENPORT.pdf


check out this book.


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## jonn (Apr 1, 2012)

Hi butcher, the first link you sent me says next to fig. 6
" the voltage is -.28 v. " 
Am I missing something? The second link is in regards to winning copper. My winning cell voltage was higher than my refining cell. I completed the winning process so I am using my rectifier for my second refining cell.


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## jonn (Apr 1, 2012)

Third link, page 328, sentence starts with: the electrowinning voltage


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## jonn (Apr 2, 2012)

Butcher, I owe you an apology. I just reread my last posts and I'm afraid I just sounded downright rude. I didn't mean mean it that way so, I'm sorry. The third link you sent me on page 328 says " the electrical potential needed for electrowinning is 2 volts as compared to 0.3 volts for electrorefining.

I think this has to do with the anode, the copper being in solution, heat and losses. Also, the winning process is ran at 300 A/M2. I have noticed that this is about 100 amps more than the first link you sent dealing with refining. I am left to assume that during the winning process there is not much concern with the solidity of the copper.?? I need to read the whole thing because I feel as though I missed something. Thank again.


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## butcher (Apr 2, 2012)

Jonn,
No apology needed at all.
I have to admit I have never studied copper refining or electro winning, I have studied battery's and electrolysis for years, I was using that as my basis for the oxidation and reduction values, I cannot say for sure what the best voltage parameters would be, or the current density for your cell, I can possibly help some with principles or theory.

I do find it strange that the refining cells would run at such a low voltage, although these cells industrially are very large, also I believe the surface area of electrodes are so large, and so close together, and amperage also seems very high, this may be different than a home setup, could you post a picture of your cells?

You have peaked my interest in this some, I will try to spare a little time to read more about this subject.


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## jonn (Jan 8, 2013)

Hi Butcher, what do you think about the cathode I sent you? Have you picked it apart yet


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## butcher (Jan 10, 2013)

Jonn, 
It is still sitting here by the computer table, I pick it up and admire it now and then, and Keep thinking about setting up my own small copper cell, to recover some of my waste for the fun of it, No I have not tried any tests, I do not think it would show much, the density, and thickness of the plating on this cathode copper kind of gives me an indication the copper is fairly pure, the color under the surface also indicates this. As I said before I am totally amazed you electro-winned this from an impure copper anode, your cathode copper came out beautiful.

I do not want to mess up this cathode, but would like to see how it would bend, I keep thinking the copper is so dense in the plating you could form it into shapes, just as you could pure melted copper (but for now I like it here just as it is, as a nice paper weight, it is nice thanks).

I still think you should make some posts on how you came up with these results, giving details.


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## jonn (Jan 11, 2013)

Thank you Buthcher, that means a lot coming from you. There is actually a way to solid plate onto or into any shapes. The plating process requires patience as it takes a while for sure, but it is well worth it. The purity is high according to the xrf, shows 999. I run multiple cathodes and that makes it worth while as it gives more weight in the same amount of time. The batch I ran your sample in was calculated at .07 cents worth of electricity. Much cheaper than melting and cleaner too. 
I will post details and pictures soon, if you think it's a good idea. I'm no pro, far from it. I appreciate the compliment. I will also post the process of making any shapes. Let me know when you get your power supply, rectifier, working. Always, good to hear from you, Jonn.


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## FrugalRefiner (Jan 11, 2013)

Jonn,

I believe a lot of members, myself included, would be interested in your process. Please do share!

Thanks,
Dave


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## jonn (Jan 18, 2013)

Thank you for the kind words Dave. It has been proven through my experience this past year that copper likes to plate out in solid form at the proper voltage. There are many charts available online and in books, all stating the same fact. The voltage for copper is .34
The process is quite simple really, melt an anode, blister copper is what it's called. It may have a few percent impurities with the balance copper. What seems to work best is 97% copper. That should not be hard to accomplish considering all the copper in electronics and ewaste. The balance or 3% would contain silver, gold, palladium or whatever else is in your scrappile. I purposely add 30% by weight additional copper. This may be reclaimed from your solutions from fingers or foils or whatever else you may have copper in that needs to be dropped. That copper powder can be added to your blister anode to achieve your 97%. A lower percentage works but not as well. I strive for at least 93% copper minimum.
The anode of blister copper and the cathode are placed no more than 4" apart in spent nitric solutions used for eliminating base metals. Once again, this contains mostly copper. The cathode should have the same area as the anode for proper deposition. If my anode is 3" x 5" then my cathode is also 3" x 5". The cathode is a thin sheet of rolled copper from the rolling mill. ( pm me if you need some rolled sheet ). The voltage is strictly controlled not to exceed .4 volts preferably as close to .34 volts as possible with a slight excess only. Once you go above .8 volts, you will plate silver.
A good source for this anode material may include silver plated copper tableware. 
I run more than one anode and cathode at the same time in a 5 gallon bucket.
I fashion a square lid for the round bucket top. In that lid I scribe a radius 4" for an 8" diameter mark. Along that mark I drill every 4" a 1/4" hole. Mine has 6 holes in it. Through every other hole I looped a #8 stranded copper wire with each end meeting on top of the lid in the center. These ends are twisted together and my negative clip attaches here.
The cathode copper starter sheets are rolled at top about 3/8" to hang on this #8 wire. This roll serves 2 purposes,
1. It makes contact with my negative voltage
2. It shortens the cathode a bit, the bottom is the strongest point of attachment and should be slightly higher than the anode in the electrolyte.

The anode holes get a drill hole in the top and tapped for a #8 stainless steel bolt with washer on top of the lid.
Take the positive wire and make 3 ends or pigtails. Crimp a round yellow terminal to each end. Insert the stainless screw and washer through this terminal. Insert this into your lid in every other hole. Thread this bolt into the top of your 3 anodes. Turn on your power source with the voltage all the way down. Immerse your plate with cathodes and anodes into your spent nitric electrolyte. Immediately adjust your voltage to .34 or just slightly higher. The amperage will adjust itself according to the size of your elctrodes and spacing. Slight agitation daily is recommended. This will take a while. It may work pretty much undisturbed except for the daily agitation. 

The copper cathode is very pure. It is hard as in pure copper sheet. It cannot be knocked off even with a hammer. It can be rolled in the mill after washing or recycled for top dollar. It is pure metal. I get #1 pricing. This is what's indeed called a grade A cathode, this is what spot price of copper is based on.
Butcher, could you post post a picture of the one you have? I sold all mine.


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## FrugalRefiner (Jan 20, 2013)

Jonn,

Thanks for taking the time to write up the details of your setup. I'll probably be trying this in the spring.

How are you melting your copper feedstock to make your anodes? Are you using a furnace or torch melting in a melting dish? I've read that oxidation during the melt is a problem with copper. Are you experiencing this or are you minimizing it by melting with a cover or a carbon source?

Thanks,
Dave


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## Geo (Jan 20, 2013)

your copper anodes will only oxidize on the outer surface. use a wire brush and brush it till its shiny.


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## jonn (Jan 20, 2013)

Geo is right, it only oxidizes on the outer surface, the surface exposed to air during the pour. I melt mine with minimal flux in a furnace. I pour the anodes into a core of sorts. I will explain, the bottom of the mold as well as the sides, get completely filled with molten copper. Oxidation is minimal in those areas. The top does oxidize a bit but it has caused no problems for me. Once cool, the anode is removed and used upside down. The oxidized portion being at the bottom. My mold is tapered at the bottom to a point. Once cooled, this point becomes the top of the anode. As the anode dissolves, it leaves less material because of the pointed top. A small portion of the top is left above the electrolyte, about 1/2". Hope this helps, Jonn


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## jonn (Jan 20, 2013)

I will post her a chicken scratch drawing, sorry about the quality, it's the best I can do at the moment


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## FrugalEE (Jan 20, 2013)

John said: "The copper cathode is very pure. It is hard as in pure copper sheet. It cannot be knocked off even with a hammer. It can be rolled in the mill after washing or recycled for top dollar. It is pure metal." 

Some years ago I electroformed some heat exchanger parts using copper sulfate solution. That copper was the hardest I've ever seen. Unfortunately my cathodes were not smooth and grew some polyps. What I would do is cut off the polyps and hammer to rehape my piece as necessary, but first I had to get the copper soft (temper it) by heating and quenching it in water. 

I have two questions:

1. Are all sucessful solid and thick electro deposits naturally hard? 

2. How can you roll copper that is hard? Is there a tempering process somewhere you haven't mentioned? Most copper sheet that one buys comes only partially hard.

Very interesting thread,

FrugalEE


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## jonn (Jan 20, 2013)

Hi frugalEE, the copper is as hard as a copper pipe or copper wire. I simply meant that it is pure solid metal, not fluff or sponge or powder. It can be hammered or rolled just like any other pure copper. I noticed growths of polyps as well if not agitated. Those would be from any dust or spec of scum that has attached to the cathode during the process. I like to agitate daily and every once in a while, I would take a horse syringe, pull some electrolyte through it and spray that directly onto each side of each cathode. In essence washing off anything that stuck and agitating at the same time.

It has been said, although I haven't tried this yet, that if you could surge the voltage purposely, it would knock off anything that applies itself to the cathode. Maybe a relay and timer could be connected Inline for that purpose? Just a thought.


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## FrugalEE (Jan 20, 2013)

Thanks John,

I used the word temper in my previous post when I should have said anneal. Annealing is using heat to soften. Copper wire is about the purest form of copper readily available and it usually comes pretty soft so it will bend. I can flatten some 12 gauge house wire up to about 3 times its initial diameter producing almost a knife blade like hardness, but without annealing I really can't get it much thinner. The copper I electroformed was hard like that hammered copper and I expect your's was too. I only know of two ways to make copper harder - work it or electrodeposit it. I still doubt that you would be able to roll your copper cathode directly very succesfully without first annealing it. I suspect copper is like gold in that it doesn't take much of some kinds of impurities to make the metal brittle and resistant to rolling, hence rolling is a test of purity. Perhaps very pure electrodeposited copper can be rolled, at least with high pressures. Also I'm wondering if it's possible in some way to electro-deposit copper with a softer temper. Perhaps your nitric deposits are softer. I did some nitric deposits and my twig like pieces are very hard and brittle.

It wouldn't take much to have a relay periodically reverse polarity or insert another power source to change voltage. I've read somewhere that things like that can be used to reduce the amount of baby sitting needed and improve deposits.

Not many have produced at bar like you have. It takes a lot of patience.

FrugalEE


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## jonn (Jan 22, 2013)

Thank you frugalEE, it does take patience for sure. But it's a nice finished useable product and the slimes can be processed for values. The electrolyte would otherwise not be used and the cost is minimal. All good reasons to be patient. I found a cathode I ran a while back sitting in my drawer, I will post a picture and then roll it and post a picture of that. I believe when rolling any material annealing is important if you intend to use the rolled product. If you roll thin and curl your sheet for parting it's not as important but still a good idea. Thanks, Jonn.


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## Oz (Feb 5, 2013)

The words temper and anneal are often misused. In general usage tempering something means only to change it by the addition of something.
I have done a fair share of blacksmithing and in the iron mongering world you temper something by adding heat, then quenching it cold rapidly to save that state of the iron. This makes an iron alloy in its hardest most brittle state. You then anneal the iron by controlled heat to soften it to the desired “temper”. 
Copper is very different in that to achieve the softest state of the material you heat it cherry red then quench it rapidly to achieve the most ductile and softest state.


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## kurt (Mar 18, 2013)

John/Butcher - first I want to thank the both of you for providing the info here on running a copper/nitrate cell & electro chemistry in general as I am planing to attempt this process in the near future.

I have read & re-read the last 2 pages of this thread 5 or 6 times now as well as looked at the links provided & I have a number of questions

I will start with a question about tin in the mix (of the anode) 

My anodes will be made up of metals smelted from incinerated high grade circuit boards such as hard drive boards, cell phone boards, ram, slot processors & chips - so tin will be a high % and I understand I may need to ad extra copper to get my anodes up to at least 93% or better copper

The question is - how does the tin "report" in this process --- another words - in theory everything below copper in the reactive serries should report as anode slime & everything above copper should go into solution (the electrolite)

However - we are using a nitrate solution as our electrolite & as we know nitric acid does not dissolve tin but turns it to tin paste (or stannic tin) so does the tin report in the anode slime & if so is that report of tin in the form metalic tin or stannic tin?

My "assumption" is that because the electrolite is a pregnant copper nitrate (or near pregnant) that the tin would report as tin metal with some residual stannic tin ?

Kurt


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## butcher (Mar 20, 2013)

Kurt, 
I cannot answer your question; here are a few my thoughts.
Tin in HNO3 does not really dissolve, the reason I believe is because the nitric is such a strong oxidizer, and tin so reactive, the tin just oxidizes, and since it does not dissolve into solution it will not pass through filters worth a darn.
so in the nitrate solution you may be able to keep some of the metastannic acid in the anode bag,
But the more you could remove before your made copper anode, I think the less trouble in your cell, I would not only look at adding copper to raising percentage, but would look into pretreatments to removing the other metals first. Like tin iron and the other base metals, with chemical and furnace treatments.

Copper is normally refined in copper sulfate cells, my guess is there must be a reason, they choose the sulfate over the nitrate electrolyte.

Tin as I understand it in these cell can partially be reduced on cathode as tin salts if the percentage of tin is too high, so I believe when electrolyte begins to become contaminated they remove a portion of electrolyte to clean it up, or replace electrolyte.

I think when they refine copper first they refine the copper in reverberatory furnaces, in an oxidizing melt, sometimes blowing in oxygen to the melt, to oxidize metals like iron, lead and tin, forming a slag, which they remove many of the oxidized base metals from the copper.

To me this sounds hard as copper can also oxidize fairly easy in a melt, so it would seem kind of art to oxidizing unwanted metal without oxidizing the copper.


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## jonn (Mar 22, 2013)

Butcher is right on all accounts. Steel would be removed first by hand, tin would oxidize and partially volatise in the melting of the anode. The flux would would remove most if not all of the tin. Any tin left would report to the slimes. Also be sure to rejuvenate the electrolyte periodically. Don't ever turn off your power supply before removing your anode and cathode, otherwise you will coat your cathode with silver as in the reactivity displacement similar to cementing. I like to spray mine off into the electrolyte before removing them. This dirty solution can become your winning cell once all slimes are removed. You would use either hard graphite sheet or titanium as the anode and a copper starter sheet for your cathode. The voltage would have to be increased. Pm me if you need graphite or titanium. 
The winning cell would remove most of the junk from your electrolyte in turn rejuvenating your solution. Eventually you would send this electrolyte to your waste cleanup,(see elephant in the room.) hope this helps, Jonn


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## kurt (Mar 23, 2013)

Butcher/John – thanks for the replies

John – what are you using to help flux out the tin ? ---I ask because a while back as an experiment I incinerated a hard drive board & then smelted it & the resulting button was still high in tin – enough tin to give the button a pinkish color 

I used soda ash as my flux – no borax as I figured the glass from the fiberglass would take the place of borax

Are you using something like ferric oxide or potassium nitrate as an oxidizing agent in your flux ?

Also I plan to order some fluorspar to use as a thinning agent in the flux to help with settling out of the metals from the slag

Kurt


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## kurt (Mar 23, 2013)

Butcher

You wrote - Copper is normally refined in copper sulfate cells, my guess is there must be a reason, they choose the sulfate over the nitrate electrolyte. 

Yes I understand this & it is especially true of copper refined from ores & as I understand it that is in part due to the nature of ores to start with

What sparked my interest in this thread back when Rusty first started it was not the idea of refining copper but rather the idea of dealing with the copper in the process of recovering the PMs for refining were in copper makes up a large part of the base metal to be dealt with

Leaching of course is one way of dealing with the base metals – but leaching presents its own set of problems – one of which is the waste generated & copper nitrate is a waste we generate in many of our process

That is what has sparked my interest in this thread – being able to utilize waste generated from other processing to deal with the copper that would other wise require more leaching which would in turn generate more waste

So ultimately the goal is not so much to refine copper – but rather recover (& then refine) PMs from “high” copper content material that utilizes waste generated (copper nitrate) in order to reduce generating more waste (more copper nitrate) by leaching

There is of course an up side & down side to each method (leaching or electrolytic)

Leaching = faster – but more waste

Electrolytic = less waste – but slower

Comments welcome

Kurt


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## jonn (Mar 23, 2013)

Kurt, you're replacing the Borax with fiberglass? From where?? Did you forget to incinerate?


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## ericrm (Mar 23, 2013)

kurt,from what i read, glass melt at 1600deg celcius , did you manage to lower the melting point enuf so it can be melt in a regular furnace?


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## jonn (Mar 23, 2013)

Try adding Borax Kurt, you will be surprised at it's color once cooled. The tin will report first.


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## kurt (Mar 24, 2013)

Thanks John – will give it a try – I just referred to fluxes in my assaying book & it list’s both soda ash & borax as complexing fluxes (meaning they cause both oxidation & reduction in the crucible) & it list’s ferric oxide & potassium nitrate as oxidizing fluxes which is why I asked

But then in the description on each flux it says soda ash will cause “some” oxidation – were as for borax it says – this is an oxidizing flux

I used soda ash without borax on that first smelt for two reasons (1) soda ash tends to run more fluid then borax & without having any fluorspar for thinning I wanted my flux as fluid as possible to reduce metal balling up in the slag (2) soda ash brakes down in water borax doesn’t - so with soda ash in the flux you can brake the slag down in water & pan out any metal that balls up in the slag --- you still need to do some crushing but the more you can brake the slag down in water the easier the crushing.

Eric – yes – silica (glass) has a high melt point (1775 C for pure silica) but in combination with different fluxes it’s melting point is reduced (the flux acts as a solvent)

Silica is used as a flux – in combination with other fluxes – in both smelting & assaying to form the slag – the silica combines with the metal oxides & bases so they are retained in the slag & not carried down with the metal

So yes – the glass (from fiber glass in CBs) will melt in any furnace we use for melting our metals when used in combination with other fluxes (if it will melt gold it will melt glass combined with other flux) & the glass is actually beneficial in the smelt --- borax will dissolve silica at assay temperatures (1850 F)

Fluxing is a science in its own – one I am still learning - any good fire assay book is a good place to start learning about fluxing

Kurt


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## kurt (Mar 24, 2013)

jonn said:


> Kurt, you're replacing the Borax with fiberglass? From where?? Did you forget to incinerate?



Yes I incinerated first - after incineration you end up with ash (from burned plastics & resin) the fiber glass (which doesn't burn or melt at incineration temps) and of course your metals --- so I didn't ad fiberglass in place of borax - I just didn't use any borax figuring the existing fiberglass would work in place of borax

Kurt


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## jonn (Mar 24, 2013)

Thanks Kurt, you pose some very good questions. My feedstock is usually different than yours, I have more copper and less tin. I think you're on to something good here and would be very interested to know how this turns out for you. Every time I had fiberglass in the crucible it would float to the top and create a sticky mess which would not melt. Adding borax has always solved the problem. Please keep us posted as to what flux combination works best for you. It would certainly solve a lot of problems for everyone. Thanks, Jonn.


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