Copper sulphate cell

[MountainMike]

Now that we are at peace with the safety issues, back to the main topic, designing a larger copper sulphate cell.

There is a Google library book, "Metallurgical and Chemical Engineering", Volumn 9, No. 9. I think GSP listed the link, I am sorry, I can not find it for you. On page 444 is an excellent discription along with anode and cathode measurements, electrical requirments, and process procedures for the Moebius style (Thum style on next page) of cell.

A brief quote "The Moebius cell...(size about 24 in. by 26 in. and 22 in. deep.) In each cell are suspended four sets of four anodes (14 in. by 5.5 in. by 3/8 in. and five rolled sheet cathodes (cathode surface 18 sq. ft.)"

It is my intent to follow the sizes given above but using only 2 anodes and 3 cathodes (all bagged) to test the design. My material varies a lot and is probably about 80% (just a guess) copper. My interest in the copper sulphate cell is to use it as a way to separate most of the copper from the slime. Any feedback to this idea would be appreciated. ~m

 

[goldsilverpro]

MountainMike,

http://books.google.com/books?id=a5DmAAAAMAAJ&pg=PA8&dq=metallurgical+and+chemical+engineering&hl=en&ei=gzajTKmeA4r2tgOuwfX5Bg&sa=X&oi=book_result&ct=result&resnum=2&ved=0CDUQ6AEwAQ#v=onepage&q&f=false

Type in 444 at the top and hit enter

The Moebius and Balbach-Thum cells are SILVER cells named for their inventors. The main difference between the 2 is that the Moebius electrodes are run vertically and the Thum electrodes are run horizontally. These cells have nothing to do with copper electrorefining. The setup, conditions, and problems with doing Ag or Cu are different. Don't confuse the two.

After re-reading 4metals' post, he was talking about melting parts that were Au plated on PURE copper. To me, this high Cu purity is the main reason the guy was successful. In your case, the copper is only 80% and you're going to have big problems controlling the cathode deposit. Once the cell has been running for a short while and the impurities build up in the solution, you're going to have a mess. The Cu++ will plate in the form of slime and will slide off the cathode. Some of this Cu will form in t*rd-like lumps which will float and can short out the electrodes. The reason they float is that they contain gas bubbles produced at the less-than-100%-efficient cathode reaction.

I think your concerns about electrode spacing, etc., are putting the cart before the horse.

Before spending the money, time, and effort building the large cell that you propose, I would set up 2 cathodes and 1 anode (or, 1 of each) in a plastic bucket. Use the proper starting solution, current density, bag the anode, etc. Let it run for a couple of days and just see what really happens. Many people, when trying this, run the cell for only 30 minutes, or so, and it seems to work. It's going to take quite a few hours to dissolve those bars and the proof of the process will be in running it continuously for a long time. I don't see this happening. At 80 amps, it will take about 180 hours to completely dissolve those 4 anodes of the size you suggested. And that's assuming 100% anode efficiency, which you'll never achieve.

You might think that a way to make this work would be to also bag the cathodes to confine the Cu deposit. However, if the bag touches the cathode, the Cu will plate though the bag fabric and this will create another series of big problems. In electrowinning, they build a cathode frame out of some rigid plastic and enclose it in a bag. The frame is made wide enough so the cathode hangs freely in the frame and doesn't touch anything. However, in electrowinning, the impurities are slight and the cathode deposit is adherent and solid. In your case, the bag would soon fill up with fluffy Cu and you'd be back to square one.

The only way I know of to run this is to separate the anode and cathode chambers with an anodic membrane. That way, no Cu solution comes in contact with the cathode, nothing plates out, and you wouldn't have to worry about any Cu slimes. However, building a proper membrane tank is quite a feat in itself and the membranes aren't cheap.

 

[MountainMike]

GSP:
Thank you for your detailed reply. I understand that the Moebius and Thum are designed for silver.
I think the concept they represent can be adapted to a small backyard type operation for breaking down anode bars of as little as 50% (maybe lower) copper. I do not look on this as copper electro refining . I view it as much more of a way of getting the anode slimes cheaply.

Your thought about the copper deposit plating thru the cathode bag by contact is valid, if, in fact the cathode is growing crystals. I feel that because the cathode will produce fluffy, loose material that will slide off the cathode, this plating thru the bag may not happen. Your idea of using a frame to hold the bag away from the cathode is probably a must, especially on the startup when the electrolyte is fresh , the cathode may in fact grow some crystals.

Your suggestion of doing a test using 2 cathodes and 1 anode is reasonable. Why not do two things at once and use this as a time to test cathode, anode size also. It is stated in the book that they used 14 in. by 5.5 in. by 3/8 in. and cathode surface of 18 sq. ft.. Do you agree with that? What would be the size of the cathode if I used only one anode?

Your paragraph about the membrane is intriguing. I have some bisque ceramic cookie jars that should work as a membrane I did a little test using an assay clay crucible (6 in. x 3 in.). It worked after a fashion but I felt the melting flask was contaminated with whatever. When I try that again I will bag the bisque container also.. This would be a modified fizzer cell.

Well, as Steve likes to say, “the proof is in the pudding”. So, I need to get started. ~m

ps: what would be the weight of the 4 anodes?

 

[goldsilverpro]

You can run twice as many amps with 2 cathodes and 1 anode as you can with 1 of each. With 1 of each, you can only consider the side of the anode facing the cathode. With 2 cathodes, one on each side of the anode, you can consider both sides of the anode when calculating how much current to apply.

The actual size of the electrodes doesn't make much difference. Just use anodes and cathodes that have about the same surface area. Only calculate the surface areas on the sides that are facing each other and not the backs.

My reason for the bucket test was so you could get an idea of what is happening before gearing up to full scale. I wanted you to see the mess after running this for an extended period of time. Consider it a learning experiment.

A cubic inch of copper weighs about .32 pounds. Each anode is 14x5.5x.375= 28.9 cu.in. or 9.2 pounds. All 4 would weigh about 37 pounds. At 100% efficiency, 1 amp will dissolve or deposit 1.18 g of copper per hour. 80 amps will do 94 g/hr. 37# is 16,800 g. Therefore, it will take at least 16,800/94 = 179 hours.

I hate to rain on your parade, but I don't think this will work as a breakdown cell as a silver cell does. Just wait until you try to deal will all those fluffy slimes and floating copper t*rds.

 

[MountainMike]

GSP:

Thank you for this additional information. I also thank you for humoring me, I always had to learn the hard way.

I have a cement vibrator. What would be your thoughts about placing it next to the cell, or even enclosed in a pvc pipe and put directly into the electrolytic. It may allow/cause the hydrogen bubbles to escape to the atmosphere . It probably would make a bigger mess then what I am facing. ~m

 

[Harold_V]

GSP:

Thank you for this additional information. I also thank you for humoring me, I always had to learn the hard way.

At the risk of repeating myself, I have experienced the precise thing Chris has mentioned in his posts. Parting impure copper is a task that is not successful in the long term, although you do get respectable results initially.

I abandoned the quest to do so after spending a huge amount of time and having built two cells. The level of contaminants in the copper creates a mess that I was unable to overcome.

Harold

 

[samuel-a]

GSP:

Thank you for this additional information. I also thank you for humoring me, I always had to learn the hard way.

At the risk of repeating myself, I have experienced the precise thing Chris has mentioned in his posts. Parting impure copper is a task that is not successful in the long term, although you do get respectable results initially.

I abandoned the quest to do so after spending a huge amount of time and having built two cells. The level of contaminants in the copper creates a mess that I was unable to overcome.

Harold

so what the bigboys are doing... ?
how do they deal with refiner's bar ?

 

[HAuCl4]

I understand the big boys are using solvent extraction selective for copper, these days, to clean up the electrolyte on a continuous loop.

I'm with GSP and Harold on this matter: Copper sulphate cells and loops are a money and time losing proposition except for the biggest scale operators.

 

[goldsilverpro]

The refiners assay the refiner's bars and pulps and ship them to a primary copper smelter, whose main business is ore, blister Cu, etc. These smelters are mainly in Europe (Belgium, e.g.). The smelter assays them and then simply blends them into their primary copper flow. The heavy concentration of impurities in the bars becomes considerably diluted from the primary copper flow and allows everything to be run through a cellhouse.

Although there may be some, I have never heard of any PM refiner that treats the bars themselves, at least on a large scale. The copper smelters are honest (since the refiner knows exactly what his values are) and pay top dollar (they even pay for the copper) so there is no economical reason for a refiner to go to the great expense of setting up to do them inhouse. Also, I would doubt that anyone could set up to do them as a service for the refiners and be able to compete with the smelters. The only advantage would be time, since the smelters take about 3 months. However, after assaying everything, the smelters will advance money with interest at the going rate. It's an excellent system for the refiners.

Years ago, I did hear of a refiner in NM that was breaking them down in a dilute sulfuric acid membrane cell and then cementing the Cu with Fe.

 

[HAuCl4]

One could use those bars to inquart and that way recover the gold and silver slowly. I'd pay 50% of the gold content for those and not in great quantities.

GSP has suggested in the past to leach the gold out of the contacts with cyanide instead of melting in a bar.

 

[goldsilverpro]

GSP has suggested in the past to leach the gold out of the contacts with cyanide instead of melting in a bar.

Many big refiners have a cyanide stripping setup for select materials. However, since much of the scrap they process is reject manufacturing scrap, this makes it easier for them. For example, they might receive 20 drums of nothing but loose gold plated pins. The main difference in most manufacturing scrap is that it is generated as the individual components rather than assembled boards. When I was deeply involved in working or consulting for refiners that mainly did manufacturing scrap, it was said that 40% of all of the gold purchased by the manufacturers ended up as some sort of scrap. That figure may be lower now.

 

[MountainMike]

Harold

Thank you for your comments and interest. What type/style of cells did you build? Did you bag the cathode? What was your electrolyte formula, and operating limits?

I asked those questions because years ago I tried something along the Tum cell idea. It worked well for a while also. It seemed to me the main problems where that the anode rested on a bed of muslin, the slime developed under and around it to the point of almost insulating the anode bar from the electrolyte. The bar being dissolved only from the bottom added to that. The cathode was a sheet of stainless, what a chore to remove the copper. Feathers/crystals would grow from the cathode and short out the anode if you did not harvest regularly. The electrolyte itself would get fowled in about a week. Back in those days nitric was cheap and fast so I dropped the idea.

Today, things are different and a revisit to the problem using the Moebius idea along with the bagged electrodes has an appeal.

In the back of my mind I am thinking, if GSP and Harold don’t think much of the idea, why do I think I am so bright, and of course I do not, but, then different thinking is that makes the world go round. ~m


ps: Just read the new posts. I guess I have not made myself clear. I am NOT interested in the copper, only the anode slimes. I am also not interested in sending it off to create a paper trail. ~m

 

[goldsilverpro]

ps: Just read the new posts. I guess I have not made myself clear. I am NOT interested in the copper, only the anode slimes. I am also not interested in sending it off to create a paper trail.

I must have not made myself clear either. I know you're only interested in the anode slimes. That's the easy part. All you do is bag the anode. However, no matter if you're interested in the copper, or not, you'll have to deal with the crappy cathode copper in order to get the anode slimes. You can't have one without the other unless you use a membrane.

I think you're making this more complicated than it really is. Just experiment on a small scale. Instead of a 5 gal bucket, use a 1 gal bucket with an anode and cathode of similar size - say, 2" x 4" or 1" x 4". Bag the anode. Let it run for quite a while, if it allows you to. Small electrodes will essentially work the same as big ones, assuming you use the same solution, current density, etc. Who knows, maybe you can figure out a way to deal with the cathode copper. Harold and I couldn't, but you're a smart guy and maybe you can figure out something that we overlooked.

This may sound stupid, but I have bagged small anodes, in experiments, by simply wrapping them totally in filter paper with a couple of rubber bands around them. Neither the paper or rubber bands will stand up in strong acid solutions but it may work in your case. Also, I used good lab grade filter paper and have never tried coffee filters.

 

[MountainMike]

GSP

Thank you for your continued interest in this project. I sure am going to give it a good try. I am ordering the bags today. I should know something in a week or so.

I have done a quick test, Tum Cell style, takes about a day for the cathode copper to creep back to the anode, it was soft not crystalin or feathery. If I harvested it regularly its seems to work. I ran it for a couple of days. It seems that a bag would not allow the cathode copper out.

Well, the new bags should be here in a few days, "the proof is in the bagging" (sorry Steve). Will keep you posted. ~m

ps: I ran the test using a battery charger, (the 80 amp is on another project) would because the power is more ragged allow the copper to drop easier? ~m

pss: just ordered the bags from Anodeproducts.com only $2.95 each (thanks for the lead 4Metals)

 

[samuel-a]

The smelter assays them and then simply blends them into their primary copper flow. The heavy concentration of impurities in the bars becomes considerably diluted from the primary copper flow and allows everything to be run through a cellhouse.

Yes, that was my theory, thank you for confirming.

i wanted to do another test with my micro cell, but this time to add 50% more Cu to the melted pins to ensure high Cu content and see how it deposite at the cathode end.

One more idea that came in my mind is to incinirate quad IC's, crush them and blend it with molten Cu, mix good and pour a bar and try it in the cell... just a thought...

 

[nickvc]

I tried this several ways and had the problems that GSP and Harold have outlined ie fluffy deposits and floating cack. The way I found past this was using a porous membrane and increasing the amount of copper in the feedstock,I think you have to have at least 95%. Copper in your anode. It worked much better with the membrane and the higher percentage of copper but it was slow and I lost interest in the whole thing,this was done as an experiment to see if I could find a cheap and efficient method to treat large volumes of gold filled and plated jewellery which didn't materialise.

 

[MountainMike]

Nickvc: Thank you for your thoughts. I also have gone through all the problems and experiments you outlined. One of my main interests with this is also a cheap and efficient method to handled large volumes of gold filled and plated jewelry . I have read all the idea’s about 95% copper etc. I am going to try the other way, make a relatively weak electrolyte, bag the cathode, and let the floaters and slim do what they want, inside the bag.. I will let you know what happens. Humble pie doesn’t taste so bad if it gets you closer to an idea, or gets a idea out of your mind. ~m

Ps: did you bag your cathode?

 

[nickvc]

Nickvc: Thank you for your thoughts. I also have gone through all the problems and experiments you outlined. One of my main interests with this is also a cheap and efficient method to handled large volumes of gold filled and plated jewelry . I have read all the idea’s about 95% copper etc. I am going to try the other way, make a relatively weak electrolyte, bag the cathode, and let the floaters and slim do what they want, inside the bag.. I will let you know what happens. Humble pie doesn’t taste so bad if it gets you closer to an idea, or gets a idea out of your mind. ~m

Ps: did you bag your cathode?

No I went for the membrane which worked fairly well but just too slow ,got fed up with the whole thing in the end as the promised volumes never materialised,but keep at it you might find an answer..

 

[nh6886]

I know this is a bit of a time capsule but after reading to the end of a very interesting thread there's no ending. Is MountainMike still around and if so would you fill in the blanks? If not did anyone hear how this worked out? Looking at the folks who didn't make this work I'm sure it's a tough nut to crack but certainly not the first one to fall to the efforts of this forum. I found this thread looking for a different one where one of the members was discussing having a waste bar checked with XRF. So if there is a better thread than this one to read about this subject please let me know.
Thanks
John

 

[kjavanb123]

I wonder the same, what happened with members who were experimenting? I am on the same path, nailed the incineration part, controlled the fumes and flying ashes, then will ball mill to mesh 20, screen the metallics, and non metallic, cast the metallics into anode, and drill sample it to find the components, then decide whether to refine myself or sell to smelter.

Regards,
Kevin