Electrolytic copper refining cell

[Geo]

A search for bone glue is depressing. I have found "hide glue" and "animal glue", which is hard to find, but not one supplier of bone glue. From the looks of it, it is a craftsman adhesive for making guitars and violins.

 

[Shark]

Geo, I ran across this but I am not sure that is what we need.

http://www.fine-tools.com/oberfl.html

Also look under the link there for "How to use Bone Glue". It tells some about the glue uses and history.

 

[Topher_osAUrus]

Poor Mr. Ed.. Going to the glue factory... :twisted:

 

[4metals]

How do you plan on dealing with the impurities? For example, I think all copper connector pins are alloys. In my experience, a build up of impurities in the solution can quickly create poor adherence of the deposit to the cathode and extremely spongy deposits.

The smelting process we discussed in a previous thread is effective at removing the base metals when sparged with oxygen and fluxed to collect the metal salts.

But still impurities will build up and the solution needs to be changed out to keep them at bay. Generally the solutions containing excessive impurities are treated with iron to drop the copper and a few other metals and this material can be smelted again or sold as dirty copper to a scrap yard. In theory bismuth will drop out just copper but considering how much more costly bismuth is than copper it isn't really an option.

Of the metals that go into the electrolyte and therefore build up Nickel is the one that is most likely to be an issue on printed circuit board feedstock. Fortunately Nickel can build up to about 25 g/L before it is an issue. Considering that is half the concentration of copper the solution is quite tolerant of nickel. Iron is much more of a problem but between magnetic separation and the ability of the smelting process to oxidize the iron out of the copper it can be kept quite low in the anodes.

 

[4metals]

Poor Mr. Ed.. Going to the glue factory...

Yup, that's where it comes from!

 

[Topher_osAUrus]

How does one go about testing nickel level in the electrolyte?
Are there visible signs to watch for?

Edit to add

 

[goldsilverpro]

A search for bone glue is depressing. I have found "hide glue" and "animal glue", which is hard to find, but not one supplier of bone glue. From the looks of it, it is a craftsman adhesive for making guitars and violins.

Try Electroplating supplies or Cabinetmaker's supplies. My Dad and Grandad were cabinetmakers in my hometown for a total of about 50 years. They always had an electric pot of hot bone glue over the workbench. Bone glue was used because it was strong and reliable, yet furniture glued with it could easily be taken apart without damaging anything. For plywood stuff, they used white or yellow glue. For fine furniture, bone glue. I don't think I've ever used it for copper plating but I have used iron-free molasses several times. I also saw urea of the long list I posted. For all of these additives, only "pinches" are used.

 

[Geo]

If even copper deposit is not necessary, are the buffers necessary? Any copper reclaimed was going to be melted and poured into molds anyway. I am not really interested in clean cathode copper sheets. I wouldn't mind it being lumpy or even granular.

 

[g_axelsson]

Note that the acid copper plating solutions are almost identical to the copper electrorefining solutions. Here's another article.

http://www.ct.ufrgs.br/ntcm/graduacao/ENG06631/5-b_copper.pdf

This is a good advice that I spotted in that article.

The copper anodes must have the correct size and geometry (i.e. flat plates larger than the starter sheets of aluminum, titanium, steel, or thin Cu foil for the cathodes to avoid heavy edge deposits)

It's well worth reading the full article, it also discusses copper winning.

Göran

 

[4metals]

If even copper deposit is not necessary, are the buffers necessary?

I don't think it really matters to commercial refiners what the copper looks like physically as it gets cast into some product anyway what is important is the ability for the cell to run continuously. Just like a silver cell produces silver all day the copper production goes consistently 24/7. The difference is it is impossible to not grow the silver in needles that must be knocked down into the cell to avoid a short. The leveling ability of the organics like bone glue allows the anodes to be closer to the cathodes as the growth does not cause a dendrite to form and short out the cell.

The beauty of this, and I think the necessity especially for a small cell, is you want to run continuously. If your cell produces a few ounces an hour, at the end of 24 hours it is beneficial to have 3 or so pounds of copper plated. Remember, the values we are concentrating in the slimes are in the 1 to 1.5% range, so if you only plate 3 pounds of copper, you only generate a concentrate with 14 to 21 grams of values (Au, Pt, Pd, Ag). So running continuously is a plus, and leveling makes that possible.

When you factor in all of the effort it is going to take to process your slimes, keep in mind that it is pretty much the same amount of work if you process one ounce of slimes or 1 pound of slimes. So I would vote to set up a cell to run continuously to accumulate the slimes generated from the collection of anode material available and know that with the leveling ability of the additives, it can run with little attention on my part.

 

[nickvc]

When you factor in all of the effort it is going to take to process your slimes, keep in mind that it is pretty much the same amount of work if you process one ounce of slimes or 1 pound of slimes. So I would vote to set up a cell to run continuously to accumulate the slimes generated from the collection of anode material available and know that with the leveling ability of the additives, it can run with little attention on my part.

Having worked with slimes from a silver cell this is certainly true they can be and are a pain to work with and seem to get everywhere,I'm looking forward to your hearing your method and see if your experiences match mine.

 

[4metals]

Nick,

Were the anodes bagged on the cells you worked with? If not they are all over the cell and truly are a bear to collect to process. But if you use anode bags, it seems to be contained in the bags. Cleaning the bags can be a chore but if done in a tank of rinse water it all does eventually settle out. If you use anode bags which run the length of the buss, they are easily emptied with a length of PVC pipe connected to a vacuum receiver by simply vacuuming up the sludge routinely. It settles in the solution drawn off and the electrolyte can be decanted shortly back to the bath. If decanting always decant into an anode bag just to be on the safe side, because, as Nick said, they seem to get everywhere and we try to minimize that. There are anode bags with a rubberized boot at the bottom, I believe the trade name is "crap trap", these are excellent for this process where you routinely vacuum out sludges and leave the bags in place.

When I processed anodes made strictly from jewelers sweeps, the slimes were roasted and ball milled then pretreated with Nitric and Distilled water, this took care of separating the silver (and rarely Pd) and the base metals from the slimes and made for easy filtration and the balance were processed in aqua regia without rinsing or incinerating.

When processing the slimes from e-waste it is different because we try to enhance filtration. The slimes are still roasted and milled but they are then treated in Hydrochloric to eliminate any tin, the bane of filtration if processed directly in Aqua Regia. They are then rinsed well and again roasted to eliminate any Hydrochloric, this allows nitric treatment to separate silver and palladium. After a good rinse and filtration, the remaining insolubles are digested in Aqua regia and refined normally.

The roasting and milling makes digestion much quicker and under no circumstances should your slimes be melted first. Melting just slows the process of digestion.

 

[nickvc]

I did my silver refining in a large 25-30 litre stainless steel cooking pot, I connected the negative directly to the pot and put the anode bars into a large plastic colander with a filter cloth all across it and connected the positive to that with a silver probe attached which needed to be replaced every so often.
I ran well over 100 kilos of sterling through the cell which was usually gold plated jewellery and I kept the silver content high by adding extra nitric to the electrolyte to dissolve more silver once I could see the start of a colour change, I only changed the electrolyte once and the cell ran all week only been switched off at the weekend.
I only rinsed the filter cloth once the residues, slimes, had built up direct into a plastic bucket and left them to settle for a few days before decanting the liquid off and transferring the slimes to a beaker for further treatment, they still got everywhere !

 

[4metals]

Silver slimes are different, they have a lot of silver in them often in chunks or large scales (kind of like high priced fish scales). With Thum cell slimes, I like to remove the entire anode cloth after draining down the electrolyte so the bag can dry out a bit. Then I fish out the big silver chunks of undissolved anode material and rinse it with a squeeze bottle right into the bag, then roll up the filter material and toss the lot into an incinerator to burn the bag. Then the powder is milled and sifted and it starts with the nitric treatment.

With a Thum cell it is tough to recycle the anode bag and they're cheap enough. It is impossible to suck the slime out of the bag as the anodes are lying right on it.

 

[nickvc]

Yep silver slimes are full of silver and all I did was dissolve the silver with nitric, filter and then go after the gold, are the slimes from a copper cell easier to treat ?
I have absolutely no idea having never run one but I will watch this thread with interest to see how to treat them and how the cell works in recovering the values.

 

[4metals]

Slimes from a copper cell are no more difficult than a silver cell, the trick is not melting them, roasting and milling them, and knowing what they are made up of. Then you just go about selecting the chemistry to pick it apart.

 

[Geo]

I had to build a new furnace from the bottom up. The burner and body is complete. I will cast the lid today. By the end of the week I hope to be pouring anode bars. It depends on if my homemade crucibles can hold up. If not, I have to order some A6 salamander crucibles.

 

[Shark]

I had to build a new furnace from the bottom up. The burner and body is complete. I will cast the lid today. By the end of the week I hope to be pouring anode bars. It depends on if my homemade crucibles can hold up. If not, I have to order some A6 salamander crucibles.

How is it progressing?

 

[Geo]

The fused clay doesn't really seem like it's going to do the job. Either I can't get the form right or the mix right. I am using fire clay and sodium silicate.

 

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