Electrolytic copper refining cell

[Shark]

Something happened, I had a reply made but it disappeared. I may have hit the wrong button, been a rough morning.

Anyway, When the majority of these anodes were made I would lift the crucible and swirl it around a few times and replace it in the furnace. I would do this a couple of times. As for the mixture, I feel I didn't leave the metal in the furnace long enough. The first few were poured as soon as the metal became fluid enough to pour smooth.

The used anode seems to be small enough that it caused the voltage to start climbing. I added another small piece to it, and it has been running with no help since this morning.

The cell with the big anode is doing just fine. No issues at all, and the cathode is starting to show substantial growth. While not quite as smooth, it isn't large enough yet to know for sure how well the growth is adhering to the cathode.

 

[nickvc]

Running a cell is always a certain amount of trial and error especially if you are not running the same material constantly, there is no shortage of information about copper cells all over the internet but ironing out the wrinkles is as much an art as a science but getting a homogenous melt is the first step so always get the feedstock well molten and stir well several times before pouring your anodes, if you still have problems with your anodes simply remelt and add more pure copper, the good thing is you have plenty of pure copper now to use, trying to increase the amount of values in the anodes will cause problems and bear in mind that there are other metals in e scrap that can also cause you problems and that will eventually foul your electrolyte.
The use of cells is a process that takes time and patience but the pay off is that you concentrate your values with little to no effort and then the fun part is recovering and refining the slimes, for me they seemed to go everywhere whatever I did so keep wipes handy and just put them in your incineration pile for later recovery.
The slimes will be mainly copper if the copper cell performs the same as a silver cell but that should cause you few problems in the recovery, it may pay to filter and rinse well to remove as much acid as possible before deciding on your recovery route and final refining.
Well done Shark and keep us informed on your progress or lack of so others can help perfect your cell operation.

 

[g_axelsson]

A very interesting thread.

It is true that there is a ton of information about running copper cells, it is a technology that has been with us for well over a hundred years now. But an overwhelming majority of papers are written about refining copper in larger facilities or in laboratory environment. Both situations deals with quite pure raw copper.

When a larger operation is smelting from ore or recycling copper based scrap the copper melt is treated with air until most of the base metals are oxidized and trapped in the slag. Zinc is boiled off while iron, tin and lead is oxidized off. The only major contaminant that can't be reduced out like that without copper losses is nickel and that ends up dissolved in the electrolyte as nickel sulfate.

For a copper anode made from electronic scrap without oxidizing out all the contaminants you could have a lot more complicated situation. The electrolyte will foul a lot faster from iron, zinc, aluminium and tin. But the biggest obstacle would probably be lead. It would form a surface of lead sulfate and passivate the anode.

The lead sulfate will collect with the anode slime, so if you get a lot of undissolvable white stuff from mixing the anode slime with aqua regia then I would suspect lead contamination as the main culprit for your bad anodes.

The quick solution is to remelt the anodes with more copper but that will make the electrolysis step take a lot longer. The more advanced solution would be to oxidize the base metals in the melt as far as it's possible. Since the main goal is to get to the precious metals, a loss of some copper oxide isn't a big deal.
I don't know the best way to oxidize the melt, maybe a more aggressive flux could be used. The big boys blows compressed air or oxygen through their melt but for the small operator that seems risky. Thread carefully!

Göran

 

[Shark]

Here is the remains of the most problematic anode. I have added a new connecting wire but it started giving problems keeping with the range of my power supply. I then switched it out for a new anode and it has been running continuously since yesterday. Right after switching them out it stopped working and was fixed right off by adjusting the location of my air line in the cell. I also had to switch the cathode out in the small cell (the same cell that was having anode problems) as it became very heavy. It weighed twice as much as my average anode. So far today has been boring watching these cells, they are just running non stop.

 

[FrugalRefiner]

So far today has been boring watching these cells, they are just running non stop.

Life is tough Shark! Hang in there. :lol:

Dave

 

[Topher_osAUrus]

This is more a curiosity than anything, but, would it not be possible to do a copper cell just like a silver cell?
By that I mean-
Shot/cornflake the anode (you would still have your corn anode shark, kind of :wink: )
Then use a double or triple layer muslin cloth for the anode filter, setting it in a plastic collander, sitting on the rim of a bowl or square tupperware tub, with the cathode underneath it?

I guess that would possibly be too inefficient when cathode cleanup came, but, still - would shot (with a "bell" contact) be better/easier? (As far as filling up the anode basket / getting the anodes to dissolve, goes)

 

[Shark]

This is more a curiosity than anything, but, would it not be possible to do a copper cell just like a silver cell?
By that I mean-
Shot/cornflake the anode (you would still have your corn anode shark, kind of :wink: )
Then use a double or triple layer muslin cloth for the anode filter, setting it in a plastic collander, sitting on the rim of a bowl or square tupperware tub, with the cathode underneath it?

I guess that would possibly be too inefficient when cathode cleanup came, but, still - would shot (with a "bell" contact) be better/easier? (As far as filling up the anode basket / getting the anodes to dissolve, goes)

Do mean like this one?




I think they would work with the right set up. My first try with the bowl went pretty good, the second try, the copper stuck so tight I had to peel and scrape it out. This is what is left. If working towards refining copper, the way a silver cell works, I believe it would work with someone more knowledgeable trying it. The two cells I am working with now are my 5th and 6th variations, and are more along the lines of what I am trying to get setup. I know, sometimes I am just a bit stubborn. :mrgreen:

 

[UncleBenBen]

I know, sometimes I am just a bit stubborn.

Nothing wrong with that. Just ask my wife! :roll:

It's been a great learning experience watching your adventures in this thread, Shark. Thanks for all the updates!

 

[Shark]

Just got a chance to check the cells today. I knew that the small cell should be close to needing a new anode but I didn't expect it to be quite this small. A quick anode swap, checked the filter and left it for a few more days yet. Running again no problems. The big anode cell is still purring along as well.

Today's anode.

 

[Shark]

Quick update. Here is the anode from the small cell. Had to swap it out for a new one.





A blurry shot of the cathode from the small cell. It could be changed today, but I am going to push it a bit and see how far it grows, so long as the power stays stable.




The cell with the large anode is doing fine, it just sits there and runs. I think it could be faster, but my power is limited in it's use. The cathode is rock solid and still shows some signs of the smooth finish it started out with.





I am not fully pleased with using air to agitate the solution as it can be messy from the mist splashing around. In the larger cell, the sides are high enough for this to not be a problem. I have to keep the small cell covered to keep the mist contained. I have some new parts to try and I am hoping this will solve the bubbling problems, and help with better circulation, as well as provide a means to filter the solution while it is in use as well. I hope to have it up and running in the next few days. If this works out decent, then I will start to add some heat to the cells and try to get them in the range suggested by 4Metals.

 

[anachronism]

I love this thread. Thanks Shark, it's really good reading.

 

[Shark]

I love this thread. Thanks Shark, it's really good reading.

Thanks, it has been somewhat of an uphill battle, but worth it for me.

Here is the anode from today. Pretty well used up.



I have two anodes running now, a very thin one from the larger cell. It gives problems maintaining a good electrical flow by itself. I now run one of the very thin ones along with one of the larger, less used anode to keep a more stable flow of current. It seems to be working rather well this way.

The larger cell has some good growth on the cathode, very solid. The anode is showing signs of erosion that is easily seen with the eye alone, but still a long way from being used up. I have put my silver stripping cell away for now and will spend that time considering this third copper cell. It is just some basic improvements over my current large cell. (at least I am hoping there will be improvements)

 

[FrugalRefiner]

A lot has been written about copper cells on the huge scale where minor variations don't mean as much. Running at a small scale like this is a lot harder. Great job Shark!

Dave

 

[Shark]

Decided to clean the small cell today, the splattering looked really bad and I felt pretty good. I shut everything down and took it outside, lighting in my building leaves a lot to be desired.





I left the material in the bottom of the cell as I am still running the original electrolyte and still hoping to push it to the stopping point. The orange tint in the center is on the outside of the glass.



Here is the cathode. It has grown a good bit and is solid, although small bits can be broken off with some effort. It started out as 1 3/4 inch long piece of 1/2 inch copper pipe. I am still pretty happy with it at this point so I returned it to the cell also.

 

[Shark]

And the two anodes for the day. The small one will be removed for remelting, the larger one now becomes the small one, and a larger anode will be added to it.









Tomorrow I try to get some better pictures of the larger cell in better light. It is running right along. The new cell is still in the works, but I may need to scrounge a few materials to get it set up the way I want it. Once I have it going I will give a few more details on the two cells that have been working the past several days, or weeks, not sure which it is now.

 

[Shark]

Took longer than I thought but here it is.

I have been having problems with the small cell since I cleaned it. I was about ready to change the electrolyte when I thought I would try something else. The thought stayed in my mind about "overvoltage". So I removed 5 ounces of the electrolyte from the cell ( this is the one liter cell) and replaced it with water. It has been running stable for about two hours now. Where as it was shorting to a high voltage every minute, two at the most.

But today is the big cell. It has been very stable, with no problems. I took it outside (better light) and took it apart for a closer examination. and was pretty happy for the most part. Very small amount of copper pieces in the bottom of the cell, and they were hard, none of the powder type that is a pain when disturbed.

Here is the cathode, you can still see the outline of the original piece.



It also started out the same thickness as a sheet of notebook paper. You can see it has grown quite a bit.


The anode is slowly being ate away. I would remind anyone that is trying to duplicate this to not put the thick side of the anode at the bottom. It goes at the top. 4Metals mentioned this earlier in his information and it is the correct way to place the anode. When the heavy side is down, it will very likely be ate in half. Where with the thin side down it will continue to be ate from the bottom up. With an anode this size or larger it becomes very noticeable. Even with the small ones I have been using it can be problematic.







And the slime's are adding up fairly well.



I have put it all back together and it started up just fine. It has a slight increase in Amps, from .75 to .84 , normal for this cell so far. The voltage is at .5 volts, down slightly after cleaning by .25 volts. I have a new cathode ready for it and I will change it if it starts acting up.

 

[Shark]

Not much to do at this point. I am waiting for the last two anodes to finish up in the small cell and I will be breaking it down. It has done it's job and taught me some things. The big cell has went through an unexpected change and I will need to start a new cathode to get a bit more information on the change, but it seems to be working somewhat better. I have managed to get the amp up to an average of 1.04 amps. That has really moved some material from the anode in the last two days. Voltage is floating in the .3 to .5 range, this variation is mainly when I mess with it. While running it holds stable around .4 volt. As the small cell goes out of use, I will be finishing up on the next cell. I am hoping to have two anodes about 4 inch diameter with a single cathode. I am still working on the cathode size for now which is limited by my use of the computer power supplies.

Here are the two anodes I removed today. The one is so thin I had be careful or it would fold up easy as paper. The two in the cell now are about 1/2 used up, so a day or two should finish them up as well.

 

[Shark]

I took the small cell apart this morning. The last two anodes were used up pretty well and the current wouldn't stay stable so I decided it was time. Here are the anodes and cathode.




While I did not get a picture of the cathode from the side it is around 1/4 inch thick and almost smooth on the back side. The cathode weighed in at 179.9 grams. Almost three times the average weight of the full sized anodes. It started out as a 2 1/4 inch by 2 1/4 inch piece of thin copper and weighed less than 5 grams total.

If I can I will do an update on the bigger cell tomorrow. A quick look this evening showed the cathode is heavy enough that the 12 gauge wire is almost to light to lift it without bending the wire. It is very heavy and quite a bit larger than previously shown. The anode has two holes in the middle of it and it is quite thin.

 

[nickvc]

That cathode looks pretty clean so the values should be building and concentrating nicely.
With the dangers of using or even obtaining cyanide for most this way seems a very good alternative to collect and concentrate values, it also has the benefit of using easily obtained chemicals and equipment although a little ingenuity might be needed to make a cell to work with individual needs.
Well done Shark and keep up the good work.

 

[Shark]

Been a long hot day, and got home later than expected. The consequences were some what disappointing, but not by much. The big cell had to be shut down, the cathode had grown some what soft, but not the powder form. But it was huge for a small cell.





When I left home early this morning, the cathode had that hard, pink copper look, by this evening it had that dark crumbly look and feel. Still, it wasn't a powder, that is always a good thing. And the anode was ate up pretty good as well. When I left there were two small holes in the center of the cathode, and appeared to be thick enough to not worry about for today. I was wrong.



It looks to be a decent amount of slime's, but will have to wait until tomorrow for better light to clean the filter bag out.



This size cell has proven to be more stable to run and more consistent to produce than the small, glass cell. I have enjoyed this one, mostly just kick back and watch it run. If I had made changes when I first thought they were needed, this cell would have ran great, and the final finish on the cathode would have as good as the one from the small cell.

I had planned to have the next version ready today, but it just didn't work out that way. However, I do have most of the materials to try one in a three gallon cell. I know what I need to mold the anodes for it, I just have to find one. That should be interesting to deal with.