# Electrolytic copper refining cell



## 4metals (Sep 1, 2016)

The principles behind a copper cell.

Our purpose in refining copper is primarily to concentrate the precious metals we have collected in copper based bullion anodes. For years I used smelting techniques, which we have discussed in the smelting thread, to separate the metals, which can be oxidized out of the copper. The remaining copper holds the precious metals, which are separated out by the electrolytic copper refining process and at the same time concentrated in the anode slimes. 

Since so many of our members pursue refining as a hobby and thus on a small scale, the beauty of the electrolytic copper process is it can be scaled to work in a tank as small as a beaker all the way up to cells the volume of swimming pools. Ironically silver cells behave the same way, once you get the hang of the chemistry in the cell, it works on 1 gallon cells (like Kadriver’s stainless steel bowl cell) up to cells making thousands of ounces a day. 

So lets start with the electrolyte. 

Copper as copper sulfate 45 – 50 g/L
Sulfuric acid 170 – 200 g/L
The following additives, used in very small quantities, are to level the deposit and affect the grain of the deposit making it denser.
Bone glue, 1 gram for every 25 pounds of anode processed thru the solution
Thiourea, 1 gram for every 20 pounds of anode processed thru the solution
NaCl, 0.04g/L

Operating temperature, 60 C (140 F) 

Anode bags 13 ounce polynap fabric. (Available from Anode Products of Schiller Park, IL)
Large copper producers control their organic additives to the point that the use of anode bags is not necessary; the slimes are pulled from the solution by filtration and vacuumed off the bottom of the cell. In my experience, I have always had better luck with anode bags, but the biggest system I have ever designed or worked with produced 200 pounds of pure copper per day. I am a believer in anode bags, most impurities in commercial copper come from carry over from particulate entrapment in the cathode deposit, and the right anode bags will prevent that. 

Current density 25 - 28 Amps/sq. ft.

Anode material is the copper collector material we produced from the smelting process with a copper content >98.5%. I should add here that I have had success while the copper content was as low as 96% if the 2 1/2% difference is metals that will not dissolve but will end up in the slimes. When the percentage of precious metals in the bar gets above 4%, aside from being a good problem to have, the anodes can passivate and your efficiency goes bad. The fix is to add pure copper and recast your anodes. Any decent sized refinery will be fire assaying their bars after they are smelted and cast anyway so this is easy to prevent. 

Large producers cast anodes which are large flat plates with tabs on top to hang directly on the buss bars but smaller producers use titanium anode hooks which thread into a tapped hole drilled into the rectangular cast anode. These hooks look like this;




Cathodes were classically a high purity copper sheet on which the copper built up to the point that they were removed and washed and cast into pure copper ingots. So the copper sheet is an expendable supply, which you will need to replace routinely. The method of choice used today is a 316 stainless steel plate which has a plastic strip covering the edges so no plating deposits on the edge. When the plating builds up the cathode sheet is removed, rinsed, and the edge covering is removed allowing the easier removal of the deposited copper. Once the copper is peeled off, the strips are replaced and the cathode plate is re-used over and over. 

Typically, a small plating unit will have 10 rows of anodes and 9 rows of cathodes. These are arranged so there is about a 2” space between the plates. A unit of this size requires a 300 Amp rectifier and can produce about 200 grams of copper per hour. I mention this size because it is fitting for a refiner who processes small quantities of copper base bullion or one that sees a lot of gold plated copper scrap which can often be melted into anodes and processed (after sampling and assay) in the cell. For some reason, this size cell, producing about 75 pounds of refined copper a week, is popular with small to medium sized refiners who do not specialize in electronic scrap but see it enough to process it in house. 

Of course this will work with a beaker containing an anode standing on one side with a battery clip (+ plus connection) connecting to the power supply, and a cathode standing on the opposite side with a battery clip (- negative connection) to the power supply. 

So what happens to the impurities that remained in your anode material?

Some of these impurities will end up in the anode slimes. These metals include Gold, Platinum, Palladium, (all platinum group metals) Selenium, Tellurium, Lead, and Tin. Silver does have some ability to dissolve in the electrolyte, but in practice 99% of silver ends up in the slimes. Some copper also ends up in the slimes but rarely more than a few percent. Generating these slimes is the main reason a refiner uses a copper electrolytic cell, but for this thread we are only discussing the process of producing the concentrate, affectionately called slimes, we will not discuss refining the slimes yet. That will have to wait for the completion of the Smelting, Electrolytic copper, Slimes refining trilogy. 

The metals that will dissolve in the electrolyte are Arsenic, (Arsenic is actually a metalloid) Bismuth, Cobalt, Iron, Nickel, and Antimony. With magnetic separation and proper treatment in the smelting process, these elements can be kept to a minimum. Fortunately copper plates out at a lower applied potential than these elements so they remain in solution. Eventually, they will require the solution to be changed out to lower their concentrations.

The copper plating baths are easily controlled with simple titrations to control the copper levels (EDTA titration) and the sulfuric acid levels (NaOH titration). While the levelers and grain density additions can be controlled in larger cells with a Hull cell test, smaller cells can even do without these additions by using the proper anode bags. One caution is excessive dendritic growth can short out plates which are closely spaced, so if you cannot tend to your cells daily and plan to run continuously, additives will buy you time between required cathode change outs. 

These are the edges of stainless steel cathodes from a clients system, they do not maintain the organics closely (they do it by pounds of anode added) and they do bag their anodes. Their feedstock is from smelted circuit board metallic fractions. 




Back in the 1980’s I was smelting prepared jewelers sweeps in a rotary furnace with copper as a collector, the PM’s were recovered in copper cells with the copper recycled back to perform duty as a collector and the PM’s collecting in slimes in the cell room which had about 10 or 12 cells (I can’t remember exactly) which processed all of the bars generated from the sweeps melting. Since all bars were assayed separately we were able to segregate the bars with PGM’s from those without and generate slimes that either had or didn’t have PGM’s in them. That made for easier recovery. The combination of being able to mix prepared and assayed sweeps into rotary melt lots and the ability to place anodes into the proper copper cell made it easier to keep the PGM’s separate. And thus a point that I may have made once before comes up again; a good analytical lab is the best support and avenue to refining success there is.


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## upcyclist (Sep 1, 2016)

4metals said:


> Anode material is the copper collector material we produced from the smelting process with a copper content >98.5%. I should add here that I have had success while the copper content was as low as 96% if the 2 1/2% difference is metals that will not dissolve but will end up in the slimes. When the percentage of precious metals in the bar gets above 4%, aside from being a good problem to have, the anodes can passivate and your efficiency goes bad.


I gather this would therefore _not _be an appropriate method to purify copper that is dropped during the acid waste management processes?

_Edit to add: Great start for a thread, too! Thanks!_


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## 4metals (Sep 1, 2016)

When you consider the metals that iron drops out of the waste solution, there is potential to have other metals in there mixed with the copper. So smelt the metal first to remove as many of those metals as your smelt allows and then you can use the smelted copper as anode material. 

I would say the benefit of this process for precious metal refining is not to clean up dirty copper, although that is exactly what is done with that material when it is shipped to a copper refiner, but our purpose is to concentrate precious metals. If you ran a cell to upgrade copper with no PM's in it I would think you would need a large operation to make it pay off at $2 a pound for copper.


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## Barren Realms 007 (Sep 1, 2016)

4metals,

Could we also include the process of using a copper nitrate cell in this discussion or would that cause too much confusion?


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## 4metals (Sep 1, 2016)

I think including the electrolytic recovery of copper from nitrate solutions (as in spent silver cell electrolyte) would make for some confusion. Let's see how this goes with an acid copper sulfate cell and maybe we can add in the copper nitrates as an option or even start a separate thread. 

When in doubt I believe it is best to always eschew obfuscation.


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## Lou (Sep 1, 2016)

Thanks for your informative post, 4metals!


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## Barren Realms 007 (Sep 1, 2016)

4metals said:


> I think including the electrolytic recovery of copper from nitrate solutions (as in spent silver cell electrolyte) would make for some confusion. Let's see how this goes with an acid copper sulfate cell and maybe we can add in the copper nitrates as an option or even start a separate thread.
> 
> When in doubt I believe it is best to always eschew obfuscation.



That was kind of what I was thinking too that was why I asked.


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## anachronism (Sep 2, 2016)

The power of a copper cell is undisputed as many commercial precious metals refineries operate on this principle completely. The slimes are where the "values" live. Treating the slimes is the tricky bit for the home refiner. Thanks 4metals.


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## Shark (Sep 2, 2016)

Is there a point where an anode can become to thick? Would the anode need to be more of a sheet or will bars shapes work? I think what I am trying to ask is what is the shape/size relationship between the anode and the cathode?


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## 4metals (Sep 2, 2016)

Most refiners making anodes for small cells that use the anode hooks, of which I posted an image of above, use anodes about 4"wide, 2 to 3" thick and as long as their tank is deep. While there is less surface area on square or rectangular anodes than the plate shape of commercial anodes, the reaction will still proceed and you will produce the desired result. Generally you want a few anodes on a bar to approximate the width of the cathode and similarly the length of the anodes serves little purpose being longer than the cathode.

If you have the ability to produce an anode that is thicker at the top than at the bottom, they will last longer before the remaining stub needs to be either re-melted into a new anode with other stubs, or placed in a titanium anode basket which has an anode bag and eliminates extra melting. While it is perfectly acceptable to use one anode basket in a cell, I would refrain from using too many as the stubs stuffed into an anode basket can become insulated from the electrical circuit if too much slime collects in the basket. Whenever an anode is removed from the cell it should be rinsed in a standing tank of rinse water and the slimes will wash off and settle in the tank where they can be occasionally recovered. titanium anode baskets come in all shapes and sizes but typically look like this;



I like to use de-ionized or distilled water for make-up of a new cell and for the rinse water to clean the anodes. The rinse water, having only rinsed electrolyte from the anodes, will not contaminate the electrolyte in the tank after it has settled so this is the source of water I use for replenishing evaporation. The copper on the cathode needs to be rinsed as well but clean distilled or de-ionized water is best as most impurities in the copper are from the electrolyte not the deposit.


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## Geo (Sep 2, 2016)

That will be way beyond my scope unless I can start moving something a bit smaller at first. I don't try to nickle and dime a project but sinking tens or hundreds of thousands of dollars into a huge project is not something I can do right now. I need to start out with just a few thousands of dollars first. I suggest we concentrate on something a bit smaller and work our way up to industry sized equipment. Raw titanium is expensive enough but having it machined and fabricated will just make it unapproachable even for a mid sized operation. It would make a great investment but the biggest reason for small business failure is not enough starting capital. Invest big without enough backing and you are doomed to failure. Sitting and staring at the thousands of dollars worth of equipment and not enough money to pay the electric bill.


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## etack (Sep 2, 2016)

The titanium hooks are like $5.00 each not much. A pretty good size hobby set up could be done pretty cheap. The higher end power supply is the tricky part. 

Eric


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## Barren Realms 007 (Sep 3, 2016)

Geo said:


> That will be way beyond my scope unless I can start moving something a bit smaller at first. I don't try to nickle and dime a project but sinking tens or hundreds of thousands of dollars into a huge project is not something I can do right now. I need to start out with just a few thousands of dollars first. I suggest we concentrate on something a bit smaller and work our way up to industry sized equipment. Raw titanium is expensive enough but having it machined and fabricated will just make it unapproachable even for a mid sized operation. It would make a great investment but the biggest reason for small business failure is not enough starting capital. Invest big without enough backing and you are doomed to failure. Sitting and staring at the thousands of dollars worth of equipment and not enough money to pay the electric bill.



If I remember right you are dealing with a scrap yard on some of this material you are working with. Now would be the perfect time for you to learn and get into a battery bank with renewable energy and talk the yard owner out of some batteries and set up a renewable energy system with DC motors to charge the battery banks.


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## Geo (Sep 3, 2016)

Funny you should mention that. MCR in Decatur went out of business. Apparently, the mother company was in a legal dispute in Ca. That caused the two local junior partners to decide to cut ties and shut down. I spoke with the local owner and he said that the partner in Cali was facing a huge lawsuit and he didn't want to be pulled into the middle.


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## Shark (Sep 3, 2016)

> Current density 25 - 28 Amps/sq. ft.



Will Voltage have any major effect or are the Amps the primary control needed?


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## goldsilverpro (Sep 3, 2016)

On pages 37-38 of the attached file is a list of copper plating additives that have appeared in the patent literature. Quite a list!

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


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## Barren Realms 007 (Sep 3, 2016)

Shark said:


> > Current density 25 - 28 Amps/sq. ft.
> 
> 
> 
> Will Voltage have any major effect or are the Amps the primary control needed?



Your voltage is what you want to be able to adjust. The amperage is the amount of energy it is taking to to do the work and that is determined by the surface area of the ( anode/cathode ) material you are running.

Same principal as using a 100 watt light bulb versus a 60 watt light bub on a 110V electrical system in a house. The voltage stays constant at 110V but a 100 watt bulb uses more energy than a 60 watt light bulb because it produces more light.


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## goldsilverpro (Sep 3, 2016)

Shark said:


> > Current density 25 - 28 Amps/sq. ft.
> 
> 
> 
> Will Voltage have any major effect or are the Amps the primary control needed?



You measure and calculate the surface area of the cathode(s) facing the anode(s) and then apply from 25-28 amps per square foot of cathode surface area. Don't worry about the voltage. Just set the amperage and let the voltage fall where it may. The amps are what does the work.


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## 4metals (Sep 3, 2016)

Setting up a small electrolytic copper cell is not all that difficult and can be done on a very small scale. The one thing you will need is a plating rectifier. Just to give you an idea of the rectifier size required, if you bought a small off the shelf 8" x 8" x 8" 2 gallon tank to set up as a cell, you would be best to have 2 anode bars and one center cathode bar. Based on the tank size in the example, a 7" x 7" cathode plate would fit nicely and also give you maximum plating area. 

So 7" x 7" = 49 sq in per side and since the cathode is in the center between 2 anode bars we double that so our total cathode area is 98 sq in. 98/144 = .68 sq ft so at 25 ASF you will need a rectifier capable of producing 17 amps. 

As you can see you will need a decent amperage rectifier to get any decent copper production out of a cell. Start shopping the auction sites for plating rectifiers because a good deal here will make everything else more affordable.

Hanging anodes on hooks is less efficient than slab anodes of greater surface area but by placing a few anodes along the length of an anode buss you can get the area required and not suffer greatly in the efficiency department. One thing I like to do is make a CPVC framework out of 1/2" CPVC pipe to hold an anode bag open and allow one anode bag per length of buss bar. If the bag is centered along the buss bar so individual anodes on hooks can be hung on the buss without the need for individual anode bags, your life and operation of the cell will be easier. This is a cell where you can see the single anode bag for each anode section. (This is a picture of a moebius cell for silver but the configuration of the anode bags is what I want you to see)




One difference you will see in the cell in the picture is the quantity of anode buss bars compared to the quantity of cathode buss bars. In electrolytic copper refining there is always one more anode buss than cathode buss. Each cathode in a copper setup has an anode on each side. In silver refining, there are cathodes on each end which only see anodes on one side.

I notice the specifications that Chris posted referenced baths operating at lower temperatures than the 160 F that I mentioned. I always prefer warmer for the simple reason that I like to see a good quantity of evaporation so replenishment can be made with settled rinse waters from rinsing clean electrodeposited copper free of electrolyte and form rinsing slimes off of anode bars when they are removed for re-casting. This means your rinse water is no longer a waste stream. To a small refiner this can be a big deal. Electricity is cheaper than hauling waste. If you are a big operation with waste effluent treatment in place, cooler may be your choice. I have no experience running these baths at the lower temperature.


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## goldsilverpro (Sep 3, 2016)

> I notice the specifications that Chris posted referenced baths operating at lower temperatures than the 160 F that I mentioned. I always prefer warmer for the simple reason that I like to see a good quantity of evaporation so replenishment can be made with settled rinse waters from rinsing clean electrodeposited copper free of electrolyte and form rinsing slimes off of anode bars when they are removed for re-casting. This means your rinse water is no longer a waste stream. To a small refiner this can be a big deal. Electricity is cheaper than hauling waste. If you are a big operation with waste effluent treatment in place, cooler may be your choice. I have no experience running these baths at the lower temperature.


4metals, good point that I hadn't considered, but totally agree with. A higher temperature would definitely reduce the amount of waste solution.

I must admit, the only part of those 2 articles I read was the list of different additives found in the patents. I should have read them closer.

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.


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## Geo (Sep 3, 2016)

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.


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## Shark (Sep 3, 2016)

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.


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## Topher_osAUrus (Sep 3, 2016)

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


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## 4metals (Sep 3, 2016)

> 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.


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## 4metals (Sep 3, 2016)

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



Yup, that's where it comes from!


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## Topher_osAUrus (Sep 3, 2016)

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

Edit to add


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## goldsilverpro (Sep 3, 2016)

goldsilverpro said:


> Geo said:
> 
> 
> > 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.


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## Geo (Sep 4, 2016)

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.


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## g_axelsson (Sep 4, 2016)

goldsilverpro said:


> 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


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## 4metals (Sep 4, 2016)

> 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.


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## nickvc (Sep 5, 2016)

> 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.


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## 4metals (Sep 5, 2016)

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.


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## nickvc (Sep 5, 2016)

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 !


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## 4metals (Sep 5, 2016)

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.


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## nickvc (Sep 5, 2016)

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.


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## 4metals (Sep 5, 2016)

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.


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## Geo (Sep 5, 2016)

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.


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## Shark (Sep 10, 2016)

Geo said:


> 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?


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## Geo (Sep 11, 2016)

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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## 4metals (Sep 17, 2016)

Nice try but you've been banned. Try reading the rules1


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## Irons (Sep 18, 2016)

I wonder if Gelatin could be used instead of Bone Glue. The rendering process is pretty much the same, except that Gelatin is purified to a higher degree.


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## Lou (Sep 18, 2016)

I have used gelatin and gotten the same effect.

It's the collagen as does the leveling/smoothing effect, so far as I know.

Lou


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## 4metals (Sep 18, 2016)

All of the classic literature gives levels of bone glue but I have heard of gelatin being used (as Lou has just confirmed) but never had any details as to concentrations. 

A few years back I had to get rid of an old friend, a horse I had owned and ridden for a very long time, Guyreba. I have always thought of him every time I see bright shiny copper plating!


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## Shark (Sep 20, 2016)

I finally got some things done and tried a very small copper cell. Not much for production but it made for a good boost in my moral as for having a working version. It is all in a 1/2 liter measuring cup.


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## Geo (Sep 20, 2016)

Nice experiment sharky. I have got what I need to get started. Now if I can get a fire lit under my butt.


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## Shark (Sep 22, 2016)

Any suggestions as to how much gelatin to use? My little cell is now forming a sponge type build up on the anode. It started when it seemed to heat up (around 150*F) then turned the solution more of a green color than blue. At the same time it seemed to slow down considerably.

Also the sponge is very loose and falls free very easily. Could it be to much nickle build up in the solution?


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## Irons (Sep 22, 2016)

Geo said:


> 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.



I think you may have trouble with the Sodium Silicate. My experience is that the Crucible will turn to a liquid at Copper Melting temperature. Fire the Crucible first and see how it reacts.


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## g_axelsson (Sep 24, 2016)

Shark said:


> I finally got some things done and tried a very small copper cell. Not much for production but it made for a good boost in my moral as for having a working version. It is all in a 1/2 liter measuring cup.


It's a start, but that power supply isn't suitable for electrolysis. The best supplies are made with voltage control as well as maximum current limits.
Too high a voltage and you will start breaking down water as well as the acid used. It's called secondary or parasitic electrode processes if my memory serves me. The gas makes for a more spongy surface. The gas that is produced could also form an explosion hazard as it is often hydrogen and oxygen in a perfect mix. Do this in a well ventilated area or outside.

Did you measure the current? The best surface is formed within a current window, not too high or too low current density. In your setup the backside of the cathode doesn't add too much to the current drawn so I would just disregard it when calculating the current density.

It's always fun to build your first cell, the only way now is to improve the results.

I haven't dabbled with copper cells in 20 years, but I basically started like you did, making a copper powder that would fall off if it got too thick. Last time I made a copper cell I managed to make a large solid copper blob at the end of a wire. It looked like a upside down coppery cauliflower.  

Göran


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## Shark (Sep 24, 2016)

Thanks Göran, your explanation just rang a bell for me. I was getting ready to set up a slightly larger cell but had planned to use the cathode and anode in the wrong order. I will be holding off a bit on the new cell until I can look at the whole project a bit closer, including the use of my power supply. I think I can make it work for the small cells, but going much bigger I will need to re think it. 

After using the set up as pictured above I added a small filter bag to the set up and actually captured some of the slimes. Those are being processed now.


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## Shark (Sep 27, 2016)

Having re weighed the anode and adding a filter bag, I ran the anode again for a couple of hours. I removed 76.4 grams from it and processed the slime's from that amount. My digital scales won't weigh it and I am to tired to dig out my powder scales since my reloading supplies are all put away, but here is the tiny button of gold.




After processing the slime's I still have what seems to be a decent amount of pgms of some type. The remains would not go into solution using cold AR, but went in quite well when heated. I used stannous to test and received a very dark, blackish result. Heating the solution to near boiling for 20 minutes still gave a very dark test result. I didn't think to dilute a few drops and retest it. After trying to drop gold again using SMB with no precipitate at all I dropped it with copper and put it away until a later date.


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## FrugalRefiner (Sep 27, 2016)

Nice work Shark! Thanks for sharing.

Dave


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## Shark (May 16, 2017)

Once again, I thought this had been posted before.....

[youtube]http://www.youtube.com/watch?v=EkAQtWuurfs[/youtube]


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## 4metals (May 16, 2017)

Very nice, can you share some details about your power supply?


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## Platdigger (May 16, 2017)

So, this is from your copper cell? May I ask what was the source of your copper?
Very nice by the way.


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## Shark (May 16, 2017)

How I made the bar can be found here... http://goldrefiningforum.com/phpBB3/viewtopic.php?f=38&t=23680 


The power supply is an old computer power supply. I have it hooked up to the 5 volt side running at .5 amps. The video was before using a filter bag to catch slime's from the bar. If you can find a power supply with an on/off switch most of them will withstand a short by unplugging them and re-plugging it in, otherwise you will kill the unit dead on the first short. I am still using the same unit and have used it in a sulfuric cell as well, but prefer my other, smaller power supply for it. I have a bigger power supply that has an adjustable volt (12-18) and amp (6-36) range but haven't tried it out yet.


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## Platdigger (May 16, 2017)

Thanks for the link Shark, but, that link takes one to the beginning of a four page thread. After going through the entire thread I came to the last post, by you, and this is what it said:

"Here is how I made the big bar in the last pictures above. While there are things that I changed later (like my shoes) the basics are the same. I thought I had posted this before, but that is what I get for thinking sometimes."

There was nothing more. I thought it may have been a picture that had failed to load so I refreshed the page, but to no avail.
I did read earlier in the thread were bars were made from copper pipe and ic legs. So, was this bar that you electrolyzed made from copper bar and "non" magnetic ic legs?


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## Shark (May 16, 2017)

The big bar is mainly copper pipe and non magnetic parts from IC's melted down from the corn ear looking bars. At the last minute I added two table spoons of the magnetic parts to the mix with a very aggressive flux.(another mistake) The results left most of the magnetic parts "floating" between the layer of copper metal, and the flux. I chipped the flux and steel away, and ran the end result in the copper sulfate. 

I may need to reword the post in the other thread. The pictures I mentioned are the ones in a post several comments about my last post. I plan on doing another video when I can as that one is rather old. I have upgraded my burner and it works way better than any I used in that thread at the time.


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## Platdigger (May 16, 2017)

Ok, thank you Shark.
The reason I was asking is because of the pgms showing up. I would imagine mostly pd.


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## Shark (Jun 21, 2017)

I have made a bit of progress with my copper cell. I finally got to hard metallic copper while trapping the slime's in a filter. Still small scale but a definite improvement. I am now running the power supply at 3.3 volt. By adding a 12volt automotive bulb in line I am able to reduce the voltage down to just under 1volt. The amperage is running between .78 and .88 with no temperature increase over the surrounding air temperatures. The build up of slime's on the anode being the main issue. It is building up enough to need shaking off every 4 to 5 hours, even at the slow rate it is running. I know the anodes contain more non copper than would be optimal and it is the reason for using the filter bag as well. (The copper in the bottom of this cell is from before getting the voltage and amperage under control and was left from the previous experiment)

[youtube]http://www.youtube.com/watch?v=ZpmI-EkBqrA[/youtube]


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## Shark (Jun 23, 2017)

I pulled the cathode today and started a fresh one twice the size of the old one. The power supply is at it's limit in the current configuration so I will need to make more changes there before anything larger can be used. The cathode is solid, very solid. I think it will do to be reused as a collector metal once again like it is. It took 72 hours to get this build up which is about 2 1/2 ounces of material removed from the anode. The slime's are adding up fairly well, but I am reusing the filter bag as is until the build up poses problems. Any how here is the cathode as it came from the cell.

[youtube]http://www.youtube.com/watch?v=OXsDG3Tkt18[/youtube]


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## Shark (Jun 24, 2017)

4metals said:


> Operating temperature, 60 C (140 F)



Is this the temperature that should be maintained in the cell, or is this the maximum? I am starting to think about a larger cell, and have ideas on circulating the solution and filtering it as it circulates. If heated I will need to be very sure the filter will withstand the solution. All of this is just random thoughts right now, but it is stuck in my head to build a bigger cell, while keeping it on a workable home scale.


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## FrugalRefiner (Jun 24, 2017)

Shark, I've been busy and haven't commented, but I love seeing what you're doing!

Dave


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## Shark (Jun 26, 2017)

Shark said:


> 4metals said:
> 
> 
> > Operating temperature, 60 C (140 F)
> ...




For some reason this kept eluding me, but I finally found it,  




> I notice the specifications that Chris posted referenced baths operating at lower temperatures than the 160 F that I mentioned. I always prefer warmer for the simple reason that I like to see a good quantity of evaporation so replenishment can be made with settled rinse waters from rinsing clean electrodeposited copper free of electrolyte and form rinsing slimes off of anode bars when they are removed for re-casting. This means your rinse water is no longer a waste stream. To a small refiner this can be a big deal. Electricity is cheaper than hauling waste. If you are a big operation with waste effluent treatment in place, cooler may be your choice. I have no experience running these baths at the lower temperature.







FrugalRefiner said:


> Shark, I've been busy and haven't commented, but I love seeing what you're doing!
> 
> Dave



Thanks Dave, I find this very interesting and enjoy it. I am working toward a cell roughly 3 times the size of the one I have been playing with. Until I can get my hands on a true rectifier it will be a slow go yet.


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## Shark (Jun 28, 2017)

I attempted to pour an anode for the new cell today and failed. I just didn't get enough heat in the metal to make a clean pour. My crucible is over it's limit as well. I may need a new furnace so I can go to a larger crucible. Here is the failed anode anyway.


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## Shark (Jun 28, 2017)

Forgot to add the current cell. I just put this one together right quick using things I had on hand. The power supply is one I borrowed from modtheworld, and just now getting around to using it. While it isn't adjustable it is doing a fair job. There is 2 volts at 1.9 amps going into the cell when starting up but quickly drops back to .8 to .9 volts at 1.9 amps. Still a bit strong but will have to do until later this week.


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## Shark (Jul 16, 2017)

I have been thinking about the nodular growth on my cathode and started looking for some answers. I found this in the PDF posted here by GSP; 

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=86&t=24397#p258175

To quote it,



> Excess sulfuric acid drastically
> increases the cathodic overpotential and introduces a smaller
> ratio of level plane of electrodeposits resulting in nodular
> precipitates. It also drastically changes the X-ray
> ...



I think that explains the nodes extending from my anode. If I am understanding this right, it also means that major changes in the amount of acid can play a critical role in how the cathode turns out. I will need to re read this some more to get a better grasp of the overall of the article. These nodes could pose a potential problem when running larger numbers of anodes and cathodes that sit fairly close together.

edited to correct anode to cathode


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## Shark (Jul 17, 2017)

From the latest configuration. This is the cell I have been tinkering with the past week or so. 




A few notes from this cell. 
When hanging the electrodes the heavier ones maintain better electrical contact. This aids in a more uniform cathode growth. Good, sound contact is important, it also aids in the uniform reduction of the anode over time. Also aids in better, more even cathode growth.

When hanging small anodes (cathodes as well) use a larger size wire. The larger wire provides a larger contact area as well as useful weight. The larger wire also makes it easier to keep contact between the wire and anode by allowing for a tighter twist where they make contact. The small wires were also a pain to keep formed properly, the slightest movement seemed to cause problems with electrical contact that wasn't as noticeable on the larger wires.

Distance between cathode and anode can cause major changes in electrical properties with in the cell. When running multiple anodes and cathodes, keep the distance equal. It was very hard to do in a cell setup such as this one, while maintaining good electrical contact.

Here are the anodes after eight days of 2 volts at an average of 1.8 amps across two cathodes that were 5 square inchs X 4 sides. 




I cleaned the anodes but some maintained a darker finish than others. I still haven't figured that out unless it is due to the anodes being from different pours. The crystalline structure in the anodes are impressive. It didn't show up until being ran in the cell for a day or so.

Edit for correct naming


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## Topher_osAUrus (Jul 17, 2017)

Shark said:


> I have been thinking about the nodular growth on my anode and started looking for some answers. I found this in the PDF posted here by GSP;
> 
> To quote it,
> 
> ...



Love the updates Shark, I truly appreciate seeing the progress, changes made, and results. It is giving me inspiration to melt and run my copper that is coming out in the iron stage of my waste treating.

I do have question though (forgive me if I missed the post regarding it), but do you mean the cathodic deposit is nodular? Or are you having some nodules grow on your anode when the cell is operating?
-if the former, the cathode deposit can be altered by acid content, also adding some gelatin or another additive (I cant remember what)

For your darker finish anodes, have you tried doing the melt with some charcoal, or a good flux covering to prevent oxidation?
There are many other things that you can use beside charcoal. A little soda ash may help as well.


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## Shark (Jul 17, 2017)

> I do have question though (forgive me if I missed the post regarding it), but do you mean the cathodic deposit is nodular? Or are you having some nodules grow on your anode when the cell is operating?
> -if the former, the cathode deposit can be altered by acid content, also adding some gelatin or another additive (I cant remember what)



They grow on the cathode. I am doing another single anode/cathode cell now testing some new things about these growth. I have added some air to agitate the solution, which some books mention will help with these growths. I don't want to change the electrolyte until I could test this stirring idea.

I also got my copy of Modern Electroplating, 5th edition. That will take some time to study. 

(I need to edit that quote to correct the "anode" to Cathode.)


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## Shark (Jul 18, 2017)

After 48 hours in my single anode/cathode cell, using the original formula for the electrolyte, this is the growth with only a small amount of air to circulate the solution. The cathode was 2 inch by 2 inch and ran at 1 volt, .75 amps.





I am very happy with this for now. There was no soft, powder type growth that can be a pain to work with. The reduction in the anode weight was 53.2 grams. I can reduce the anode faster but it runs the risk of loosing PM's into the copper that falls off and settles into the bottom of the cell. This provides a potential contact point for a shortage that I prefer to avoid. I am not looking for a super smooth finish, but would like an even growth that the new cathode is exhibiting now. Keep in mind the goal is to remove the copper from, and collect, the PM's. Not to produce high quality copper. I do forget this at times as I study and try to apply what I learn.  


This is part of the slime's collected from the bigger, multi electrode cell. A small bit is still attached to the filter bags that I will deal with later. (the glass is 3 3/4 inch in diameter)


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## nickvc (Jul 19, 2017)

The darker coloured anodes may show more values than the others as they appear very similar to cemented values on copper, I could well be wrong but it's worth mentioning.


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## Shark (Jul 19, 2017)

This is what I thought also Nick, but the dark finish was firmly attached. I even tried to brush it off with a tooth brush out of curiosity. It is possible that the dark ones were shorted and this caused some kind of reaction I haven't been able to figure out as well. I am running two of them now in another cell by their selves and they are continually passivating. Is it possible that it is some effect of polarization? I may try and reverse the polarity for a few minutes and see what the effect would be.

Edit to add

From Modern Electroplating 5th Edition



> Plate characteristics are improved, solution
> conductivity is increased, and anode and cathode polarizations
> are greatly reduced when free acid is added to either
> solution [26, 66]. The acid also prevents the precipitation of
> basic salts.



Might be time to try adding a small amount of sulfuric acid.


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## nickvc (Jul 19, 2017)

It may be that the value content is causing the problem or other metals that do not easily slough off.
I'd suggest re melting with more copper and see if they behave then, using mixed metals it's possible certain bars will have greater contaminants including values that can cause this problem.


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## upcyclist (Jul 19, 2017)

If the discoloration is indeed a skin of metals (precious or otherwise) that are passivating, would it not also be possible to saw or file a notch into the bottom of the anode, thus exposing the purer copper? Then the skin would eventually slough off and end up in the filter bag (or remain as a hollow shell)?


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## Shark (Jul 19, 2017)

upcyclist said:


> If the discoloration is indeed a skin of metals (precious or otherwise) that are passivating, would it not also be possible to saw or file a notch into the bottom of the anode, thus exposing the purer copper? Then the skin would eventually slough off and end up in the filter bag (or remain as a hollow shell)?



I have no idea at this stage. I added one ounce of sulfuric to one liter of the electrolyte with no notable change over a one hour period. I just have used one of the dark anodes and reversed the polarity for 3 minutes. Nothing else was changed except for the addition of sulfuric acid prior. The brown color was lightly covered in clean copper plate. At that point I switched the polarity back and in 5-6 minutes it stopped again. I took the anode out and washed it in my rinse container and the coating came right off. It is now running, although it still passivates every 20 minutes or so. I can shake the anode and it will go back to working for a few minutes. I have no idea why some had a coating hard enough to stick that tight and others didn't. I do know some of the anodes are well above the percentages of PM's that are the normal suggested levels. I will just keep cleaning them until they are done for now. 

I am also wonder about sonic stirring. Could it somehow be used to agitate the solution (I know air agitation greatly improved the smaller cells), and shake the PM's from the anodes at the same time? If that would work it would really make these small cells with anodes of higher percentages of PM's less labor intensive.


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## upcyclist (Jul 19, 2017)

Shark said:


> I do know some of the anodes are well above the percentages of PM's that are the normal suggested levels.


It sounds like Nick had the right idea, then--add some copper to your anodes to bring the purity up a bit. It'll use fuel & time, but it sounds like it might be faster overall than babysitting the anodes by having to shake them every few minutes.


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## nickvc (Jul 20, 2017)

Shark remember the mantra of any electro refining process, high percentage anodes work for longer and better whether it's gold, silver or copper as it stops fouling of your electrolyte and produces better results for the targeted metal. 
When your melting various types of scrap it is hard to get consistent results for your anodes, not your fault it happens but save time and effort and just add more copper, you now have plenty spare, to the resistant anodes and re melt them and put them back in your cell and walk away and let the cell do the hard work.

In fact now you have excess pure copper add some to all your future melts and hopefully the problem will cease altogether.

Edited for an extra thought :shock:


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## Shark (Jul 20, 2017)

I agree guys, adding the copper would be the fastest way to get an anode that runs with least amount of hassle. The anode I ran from a piece of clean copper pipe went very fast, and smooth. Anyone trying to get started in this needs to start with a fairly pure anode to get the feel for it. 
BUT.... I got it to work by adjusting my air line in such a way to gently shake the filter bag. Just enough movement to keep a decent sized spot of the slime's cleared off enough to allow it to run all night. In fact just a few minutes ago the wire used for the connection broke(ate to thin by the cell action). The anode is small enough I would normally add it to the pile for remelting, but I am thinking I may try to add a new wire and see if I can run it a little longer. I will post a picture of it later, after attaching a new connecting wire. 

Thanks for the input guys, it always help to get new insights into this. This is my first cell as I have never ran one for silver.


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## Topher_osAUrus (Jul 20, 2017)

Shark, how were you homogenizing the melt, before pouring the anodes?
Did you stir with a carbon rod or anything?


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## Shark (Jul 20, 2017)

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.


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## nickvc (Jul 21, 2017)

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.


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## g_axelsson (Jul 21, 2017)

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


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## Shark (Jul 21, 2017)

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.


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## FrugalRefiner (Jul 21, 2017)

Shark said:


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


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

Dave


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## Topher_osAUrus (Jul 21, 2017)

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)


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## Shark (Jul 21, 2017)

Topher_osAUrus said:


> 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?
> ...




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:


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## UncleBenBen (Jul 21, 2017)

Shark said:


> 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!


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## Shark (Jul 22, 2017)

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.


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## Shark (Jul 24, 2017)

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.


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## anachronism (Jul 24, 2017)

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


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## Shark (Jul 26, 2017)

anachronism said:


> 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)


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## FrugalRefiner (Jul 26, 2017)

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


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## Shark (Jul 27, 2017)

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.


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## Shark (Jul 27, 2017)

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.


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## Shark (Jul 30, 2017)

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.


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## Shark (Aug 3, 2017)

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.


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## Shark (Aug 4, 2017)

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.


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## nickvc (Aug 5, 2017)

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.


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## Shark (Aug 5, 2017)

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.


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## modtheworld44 (Aug 25, 2017)

Hey Shark!


Here's some pictures of my copper crystals,sorry it took so long.The biggest one is about a half dollar in size and 1-1 1/2 inches thick.I'm up to about 20+ pounds now in my five gallon bucket.I've got a nice little pile of gold foils in my anode basket.Thanks for sharing in this thread,it helped a lot in coming up with my new cell.Thanks for being a great friend. :mrgreen:



modtheworld44


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## Shark (Aug 25, 2017)

That is some chunky copper! :shock: 

That is pretty close to what I am thinking will come from a chloride based cell. Maybe not as big, but hard copper deposits that should drop away fairly easy.


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## snoman701 (Nov 10, 2017)

In other threads, a membrane is mentioned between the anode and the cathode. I have assumed this to be a membrane in excess of the filter bag to catch the slimes. Further, my assumption is that this membrane is used to keep only clean electrolyte around the cathode, to prevent passivation. 

Can anyone describe this membrane and it's purpose?

Nickel still seems like the stopper here. Reported numbers of 3% by weight in pins, would only allow one to run a kg of pins / liter electrolyte. If I understand correctly, the "industrial" version of nickel treatment is essentially to first electrowin a lot of the copper, then the bismuth and antinomy, then add electrolyte back in to electrowin the arsenic (if present) as Cu3As. If your addition of electrolyte was correct, you should now have mostly nickel in your electrolyte. Now you concentrate the solution to concentrate out a nickel sulfate with lots of impurities (iron, calcium, bismuth, antinomy, etc). You've now got acid again, but it's contaminated with the organics. 

Are there nickel specific ion exchange resins that will collect the nickel from sulfate solution? Even if you first electrowin a majority of the copper from solution. Then it's just a matter of adding copper back in to solution once the nickel has been removed. I can see this being successful if that is the case, but the process of concentrating nickel sulfate/sulfuric acid electrolyte to the point of crystallization is a stopper for me.


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## Shark (Nov 10, 2017)

I haven't had time to try it yet, but by reducing the solution to 60% of the original volume, it should allow the nickle to drop out as a sulfate. You can then filter it and reuse the solution. I think 4metals mentioned it in a another manner as he was thinking about a lot larger cell than I used. I am thinking lower heat, in the 140F to 150F range, and slowly reducing the volume, which should be mainly the water in solution. I have had a lot going on lately and haven't got back to trying much with these cells other than a few small tests and a bit of reading. The key, I think, would be to remove as many metals as possible before hand and in the smelting process.


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## FrugalRefiner (Nov 10, 2017)

Given the relatively low prices of copper and sulfuric in a copper cell compared to silver and nitric in a silver cell, is it worth the time and effort to recycle the electrolyte? I really don't know. I'm just posing the question.

Dave


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## Shark (Nov 10, 2017)

FrugalRefiner said:


> Given the relatively low prices of copper and sulfuric in a copper cell compared to silver and nitric in a silver cell, is it worth the time and effort to recycle the electrolyte? I really don't know. I'm just posing the question.
> 
> Dave



With the majority of the material I am running, I am still not sure that recycling the solution is worth it on a small scale. By just removing the nickle, (in my case the majority of the contaminants) my electrolyte should gain a fairly longer useful life. The down side is that the time it takes to clean it up, I can make up new electrolyte, have it running, and enough time to see that the cell is running right again. I do have ideas on removing the nickle as a sulfate, while the solution is in a circulating system but I need time for some simple tests to see if some of the parts will hold up to the heat. So many things to try and not enough time.


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## snoman701 (Nov 10, 2017)

FrugalRefiner said:


> Given the relatively low prices of copper and sulfuric in a copper cell compared to silver and nitric in a silver cell, is it worth the time and effort to recycle the electrolyte? I really don't know. I'm just posing the question.
> 
> Dave



I just got 2 gallons of nitric for free. His outlook, "it costs me $0.50/lb, you helped me out elsewhere".

The acid is the cheap part, the costs being nearly negligible once you start to look at this from a business perspective. The waste, and the payroll are the expensive part. You have to treat the waste irregardless. If you can adsorb the nickel on to ion exchange resin, you get to use that electrolyte that much longer, at least until you end up with another contaminant fowling the electrolyte.


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## Richard NL (Dec 24, 2017)

Modern Electroplating, 5th Edition:
http://allaboutmetallurgy.com/wp/wp-content/uploads/2017/03/Electroplating-M.pdf

Happy Christmas Richard.


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## autumnwillow (Dec 30, 2017)

Is it advisable to cover the entire cell with a plastic wrap/cling wrap to prevent any evaporation which may lead to evolution of corrosive gases?

I have plenty of equipment that can oxidize easily in my office that I do not want to corrode and unfortunately there isn't room for my fume hood.

Shark have you tried melting the copper?


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## Shark (Dec 30, 2017)

I wouldn't try running this cell in a office environment. While it dosen't seem as corrosive as Hydrochloric, my area had very little metal around the cells. I have melted small amounts of the recovered copper, but not by itself. I have added it back to other melts where I melted more PGM material along with some clean, fresh copper. I have a newer cell I want to try, but I can't seem to get caught up enough to try it.


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## UrbanScrapper (Feb 9, 2018)

If you are using a computer power supply or any other DC power supply that is not adjustable, find a Buck Converter ( https://www.ebay.com/itm/DROK-DC-DC-Adjustable-Buck-Voltage-Converter-Stabilizer-Step-Down-Voltage-Red/311656730668?hash=item489030502c:g:I20AAOSwGXtXh6E0 ) This one (not my eBay store I just searched for one that shows V and A) would do the trick.


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## Martijn (Jan 16, 2020)

Hi, first of all let me say thanks to 4metals for this excellent thread and shark for all the testing and info given. Really an awesome read and great info. 

I'm starting a first test and not sure if the 50g/L is copper sulfate or sulfate made of 50 grams of copper? I've made 250g copper sulfate crystals. So i have enough for a small test cell of 600ml electrolyte. If I follow the recipe as I read it now, it would take only 30g of CuSO4 for this cell. 

I calculated that about 40g of copper would make 100 gr of copper sufate so that would mean 125g of copper sulfate per liter to make it in that case. 
I'm probably overthinking it but really not sure.  

To give some more info on the intended test: 
My anodes are made of pins with tiny bits of leftover gold plating from the sulfuric stripping cell and I want to see if I can squeeze the last bit of gold out. And get acquainted with the process. And find the right material for my anode bag. And learn much more... I hope. 

The cell for the test is a stainless steel bowl in a holder to prevent knocking it over and spilling. All this will sit in a plastic basin for safety. 
On top is a plastic beaker suspended with some holes in it all around the side and a very fine woven plastic fiber cloth as the anode bag, like those see-through window drapes. The bottom inch of the beaker is left intact to catch any slimes that might seep through. 
My power supply is adjustable up to 40 volts and 3.5 Amps, also adjustable to a max limit. Only a few volts needed, so perfect for a small cell like shark's one.

I expect a lot of tin and/or zinc from the brass pins, and maybe some nickel from the 'underplating'. Dissolving one pin in nitric made some tin paste. 
I just melted some pins in a graphite crucible in a charcoal fired, forced air furnace. Try saying that fast five times  No major fluxing or oxygen sparging. 
Only used a little borax. 
So the anode will probably passivate or foul the electrolyte pretty fast, but thats what testing is for right? I will need to be able to clean the dirty electrolyte too. 
Practice makes perfect. 
Once i have this process kind of under control, I intend to fill the basket with cleaner copper shot like the silver cell. Has anyone tried that? I saw the stainless steel bowl in this thread, but not clear if he used shot or not.

But if anyone can clarify the amount of copper sulfate needed per liter, would be great. I'm confused. 

Martijn.


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## Shark (Jan 17, 2020)

This is where I got the formula I used to calculate how to make up my small cell solutions. It has been quite a while since I worked with these but it was a lot of fun and made for a very nice change of pace from chemically working with gold.

https://www.thinktink.com/stack/volumes/voliii/consumbl/cplatmix.htm

I used pins in several of my anodes and they work, downside was the nickle under plating played havoc with the electrolyte pretty quick.


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## Kaiser613 (Feb 4, 2020)

Concerning nickel fouling the electrolyte, 

Why couldn't you just increase the voltage and plate out the nickel, zinc, and other dissolved impurities, with graphite anode, cathode either graphite or nickel, until solution is depleted of dissolved metal and reuse?


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## Martijn (Feb 5, 2020)

I was thinking about testing that. Have half a liter pale blue green electrolyte.


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## anachronism (Feb 5, 2020)

Martijn said:


> I was thinking about testing that. Have half a liter pale blue green electrolyte.



Probably not worth the time spent and equipment cost required to learn how its done.


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## Kaiser613 (Feb 5, 2020)

So I went to the local hobbyist electronic shop today and left with a (not so cheap) 3a rectifier my first cell is producing lots of bubbles from the cathode, presumably hydrogen? I don't think this is supposed to happen if the cell is operating properly for out metal deposition purposes? Why would this be happening? I'm thinking not enough copper in solution?


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## anachronism (Feb 5, 2020)

What's your cathode material and your electrolyte?


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## Kaiser613 (Feb 5, 2020)

Cathode is a piece of clean copper grounding wire, anode is a peice of dirty copper pipe, along with some small pieces of brass and copper held together in a piece of synthetic mesh fabric


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## Kaiser613 (Feb 8, 2020)

My first cell (vertical in a half gallon jar , submerged cathode suspended anode) did nothing but produce a few liters of black waste solution and a lot of bubbles, upon closer inspection the only plating that occured was the tinned wire connected to the cathode gained a copper finish, I feel solution conductivity was the limiting factor. So today i put together a new cell, (have no cuso4 on hand so spent a day reacting copper into diluted sulphuric until decently saturated) in my first cell I used a peace of synthetic mesh fabric rubber banded across the mouth of the jar as a "basket" for the anode material, but the fabric had significant capillary action, enough that the edges hanging outside the jar continuously dripped electrolyte, this reminded me of salt bridges in galvanic cells, so I put together the cell pictured (if my pictures show up, in having problems uploading pictures taken on my phone)the anode is a piece of copper pipe and the cathode is a piece of titanium tubing, as it runs (at Max voltage for my psu about 30v) the anode half cell solution saturates with copper sulfate until it collects as powder at bottom of half cell, and cathode solution depletes of copper, the first time it was ran (pictured) the depleted solution changed from aqua blue to reddish brown, bubbling at cathode is minimal while solution is blue but intensifies as solution quality drops, deposition quality is medium high, but moving cathode knocks off the bumpier pieces. I then switched the electrodes to opposite half cells, the red-brown solution has sinced been restored to saturated blue, the other solution has been again depleted but is a milky white now, the "salt bridge" is passing current but does not seem to be transporting any ions, this whole cell is very high resistance and runs quite hot, the fabric dries out frequently, walking inside for 15 minutes burnt a mark onto the synthic fabric.


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## Shark (Feb 9, 2020)

If you go back to the very first post you will see the amps should be 25 to 28 amp per square foot. A square foot is 144 square inches. 144 divided by 25 equals 0.1736. 144 divided by 28 equals 0.1944. Your max amp should be between 0.1736 and 0.1944 per square inch. If you raise it higher it can/will start to bubble and off gas which is wasting energy as well as filling your work area with hazardous gasses. You can get copper sulfate at most home improvement/hardware stores in the plumbing section and a little goes a long way. Also when you run a high amperage your cathode will be a soft, flaky deposit that falls away very easily and causes problems. Keep it with a steady amp in the correct range and it will plate out hard and solid and much easier to reuse than the flaky stuff. 

This now brings me to another idea I have been curious about and want to try. If the loose deposits can be washed enough to make it a form of copper powder clean enough to be used to cement solutions of PM's such as the stock pot? I might need to revisit a small copper cell this spring.


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## Kaiser613 (Feb 9, 2020)

Shark, I haven't measured the surface area of my cathode, but it's about 4 inch long approx 1 inch diameter tubing ( it's been mentioned only to count the side toward the anode but the whole surface collects deposits so?) With a deeply currogated surface, a rough estimate , if the currogated doubles the surface area, is 25.2 square inch on the outside only, inside surface collects too so... Well below suggested amp density, esp since yesterday I switched out the 3a Max psu with an 18v/1a DC adapter, so as to save running hours on the switching supply

My to do list today is to see if I can restore the black solution from my first cell by processing through the anode half cell and try to get a ride to the big orange homeless despot for some root killer, 

What %by weight is copper sulfate copper?


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## Shark (Feb 9, 2020)

I always measured my cathode by the side facing the anode as a general guideline. Once running I would drop back the amperage based on the amount of bubbling I noticed. Keeping that under control you will see the deposit become very solid. So solid that cutting it in half will show a crystalline structure inside. Running it to high it becomes very soft and "mushy" for lack of a better description on my part. This can easily be scraped off even with a limber piece of wood or plastic spoon. It also helps if the anode and cathode can be close to the same sizes. Both being a piece of 4 inch by 4 inch for example. It can vary some, but seemed to work better if they stay close to the same dimensions. Split your pipe open and flatten it out, I think you will find it works better that way. Keeping things simple in the beginning is very much easier than trying to figure out all the oddities when you keep changing things around. 

If I was starting out now, I would use a lab bench type power supply. Mine will do 30 volts at 10 amps. More than enough for a decent sized, basic cell. I also would use pipe split open and of equal sizes to get the feel for how these cells work, then move on as I learned more and actually seen how they work. I learned a lot doing these cells, and it certainly helped me to get started with silver cells more easily.

One other thing that can make a huge difference is distance. You can change the amount of volts and amps by changing the distance between the anode and cathode. If your power supply is small, you can aid it by varying the distance. It takes some experimenting but it can play a major role in how your deposition occurs.

I have always used Zep brand Root Kill. It comes in at 99% by weight Copper Sulfate Pentahydrate, with 1% other ingredients. I use it because it is what is easiest for me to get, I am sure other brands will work as long as the concentrations are high.


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## Thipdar (Feb 10, 2020)

Kaiser613 said:


> ...and try to get a ride to the big orange homeless despot for some root killer...



I used Amazon to get my Copper Sulfate, US$30 for 10 pounds and free delivery if I exercised my patience.
I've since obtained a new 2-gallon bucket with sealing lid for storing it.
Wrote the contents and the date on the bucket & the lid.
Bucket & lid were found in the HD paint department.

-- Thipdar


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## Kaiser613 (Feb 11, 2020)

I didn't double post


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## Kaiser613 (Feb 11, 2020)

Bought some zep and put together larger cell, finally got hard pink metallic deposit, also got a peace of silver plated(I think) so that might to in the cell


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## Rahul (Jan 3, 2021)

Hi sir,

I get impure anode mud how can i refine it ?
Please help me out on this .


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## Martijn (Jan 4, 2021)

I would like to get pure anode slimes too  
But seriously, what did you expect, and what did you get? 
Are you used to getting 'pure slimes' or is this your first attempt and did not expect this result?
How far are you in recovering and refining experience? 
Tell us a little more about your process, source materials and background. 

Martijn.


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