Copper sulphate cell

[samuel-a]

As promised, today i builted a copper sulphate cell on a bit larger scale.

as anode, i used a 45 grams of partially plated pins that melted together , but i was not able to alloy it completely, the maap is just not enough in a shallow melting dish, anyway, i got it to a nugget like state, vary in colors (golden, silvery, red and black).
it supposed to be copper,nickel and gold, i made sure no kovar was there.

as anode, i used a copper slab.

the electrolyte is 5% solution of sulfuric acid.
Harold, as a comment you made about the electrolyte , i learnd that as long as the cathod and anode are in and doing their thing, the concentration of copper in the solution will remain the same, that can be noted also by the color of solution (lite blue) that remains the same.

under the anode i placed a small plastic evapotation dish (with some copper wires to keep it submerged, but changed it later with some pieces of glass from a broken stirring rod) to collect the goods.
there are some floaters, but only because i played with the anode. maybe i'll use a porous barrier next time, but dosn't seems very needed as long as i don't tuch the anode.

the cell is running on a cell-phone charger, 5V / 1A


now for some picture and construction of the cell:

the anode and cathod is hanged with some steel rods that ware placed in grooves on the lips of the container.
as you can see in the picture, the cell is runing on full capacity of the charger.



this is the copper slab (cathod), at first and after the 2 first hours of work, you can see in the dish what seems to be pretty pure copper (very fluffy), came right off with a squeeze bottle, leaving the the slab clean.
afterward, i had to clean the cathod every hour or so.




the project is still in a learning and experimenting mode , and i'm open to ideas and suggestions.
as expected, the stripping (or more correctly, recovering of copper) is slow process and maybe suitable and more economic for larger scale operation.

i'll update when finish with this nugget and how i treat the residue on the bottom of the dish.

 

[Anonymous]

is that red powder in the bottom the slimes from the copper, or copper that dropped off of the cathode? does not look like you have a seperator between the cathode and anode to keep the copper that falls off the cathode from mixing with the gold/silver particles that fall off the anode.

I would also increase the copper sulfate in your electrolyte, you can use old copper chloride from the AP process to do this, just mix with sulfuric acid and boil the HCL will boil off and leave you copper/nickel sulfate.

Jim

 

[samuel-a]

i can see the confusion.
from the anode, everything is falling down to an a collecting dish.

this is not the same dish in the photo (no. 4).
in the photo is the copper that cemented on the cathod and rinsed down.

from the cathod, nothing is falling, and even if it will, it will not mix with the PM's in the collecting dish.

here is a scheme:

 

[Anonymous]

Now that you point it out to me, I see that the small container was in the larger one. I would let you know though that it would be possible for some of your gold to migrate over to the cathode area because of the small size of some particles and there will be a flow of liquid in the electrolyte induced by the flow of electrons.

I like the possibilities of this if the copper is recoverable and salable could work with just the simple chemicals. Would be nice if the gold could content was higher, like from maybe gold filled material.

Anyways, looks nice to me.

Jim

 

[samuel-a]

thank you.
i did noticed a flow in the liquid, and i don't rule out the possibility that some PM's is migrating toward the cathod.
wather it's cementing on the cathod or not i don't know.
i'll try next time to use a porous cup to see if it catche's somthing.

at the end, i'll melt the copper that came out of the cathod and see...
i wonder how a botton of copper should look like when it's contaminated with a bit of gold or silver or both, and alloyed real good.

 

[4metals]

Copper sulfate plating baths are a great way to recover the PM's in copper based refiners bars. One guy I consult for gets in gold plated lead trim which is on pure copper base metal. When I first met him he was digesting this stuff in nitric and using a lot of acid. Now he melts the scrap into anodes 1 inch by 3 inches by 18 inches long and recovers the copper. Plus he knows the assay for the bars before they go into the shop, not like the old days when he knew the content only when it came back form the shop.

almost forgot where I was going with this :roll: he is able to process different jobs at once in the same cell by bagging the anodes separately. You can have anode bags made of a variety of baths for surprisingly little cash. For example anode bags of heavy polypropylene for anodes of this size, 1 x 3 x 20 with drawstring ties, cost $2.95 each. And they're custom made. Check out this guys website, he supplies all different fabrics and explains which fabrics are good for which solutions http://www.anodeproducts.com

He also sells titanium anode hooks.

 

[goldsilverpro]

You probably have about 0.1% gold, 3% nickel, and about 97% copper. In a highly acidic sulfuric solution, the nickel will dissolve but it won't plate out. The copper dissolves and plates out. If the pins were made of brass, this wouldn't work, due to the added zinc and/or tin. If you add other metals that will dissolve and co-deposit, you will soon have the deposited metal sloughing off the cathode, floating in the solution like t**ds (that's what it looks like), and shorting out the electrodes. It will only work for the pure system you have now.

I think that all 4 of these things are absolutely necessary to achieve any success in doing this.

(1) The solution makeup you're using will never produce a decent copper deposit on the cathode. For best results, I would suggest starting with a solution designed for getting a proper solid deposit. Here's a post I made that details a common solution makeup used in a copper refinery. You can vary this somewhat but, if you want this to work, the starting solution will be very similar to what is given. The main thing that controls the characteristics of the copper deposit is the solution makeup.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=45&t=5396&p=46132&hilit=anaconda#p46132

(2) As 4metals intimated, you must use a metal that is inert in the sulfuric to hang the copper anode on. Titanium is one of the few metals that will work for this. The copper wire you are using will soon dissolve and the anode will fall to the bottom. You could drill a hole in the bar and use copper wire to hang it, but the wire and the top part of the bar will have to be kept out of the solution.

(3) As 4metals said, you must use an anode bag to catch the gold particles and prevent them from co-mingling with the rest of the stuff in the tank. Your primary goal is to get the gold. Keep it confined so you don't lose it.

(4) For best results, you must use the proper temperature, cathode current density, and anode to cathode ratio.

For only these 3 metals, there is no need to use a porous cup or membrane. If you start properly, this will work.

This isn't an intuitive thing. You can't just pull things out of your butt and use them (5% sulfuric, 1 amp, etc.). The copper refining cell is one of the most studied technological systems in history. To do this properly, you are foolish not to use all of the tons of info that is readily available to you. Don't try to re-invent the wheel, at least in this case.

 

[Scott2357]

What is the optimum voltage/current for this process?

 

[goldsilverpro]

If you have a 2:1 anode:cathode ratio, if the solution makeup is proper, and if all the other parameters are within range, the proper cathode current density is about 12 to 16 amps per square foot (it's in the link I gave). Here again, if everything is set up properly, the voltage will automatically fall into line. I would guess it would be about 2 to 3 volts. The amperage is primarily what's important - that's what creates the deposit.

The primary thing is to dissolve the copper and collect the gold in a bag. The secondary thing is to deposit the copper in a solid form. Although you might be able to sell copper in this form, that's not the main reason for doing it. If it doesn't deposit in a solid form, it will slough off or fall off as a powder and will interfere with the working of the cell and the gold collection.

Usually, when someone first tries this with a poor setup, all goes well for an hour, or so. They then think they have a workable system. However, for this to work, it may have to run for days. Consider that for each amp run for 1 hour, only 1.185 grams of copper dissolves and plates out - it takes awhile to do this. When they try running for longer periods, they find that things get progressively worse and, at some point, it gets so bad that they have to shut the system down. If you do everything right, this system will work essentially forever - or, at least, until contaminants, such as the nickel, build up in the solution to a level that causes problems.

 

[Harold_V]

When they try running for longer periods, they find that things get progressively worse and, at some point, it gets so bad that they have to shut the system down.

It's much easier to tell them than to have them believe it's true.
What Chris said is exactly what I experienced.

Harold

 

[nickvc]

When they try running for longer periods, they find that things get progressively worse and, at some point, it gets so bad that they have to shut the system down.

It's much easier to tell them than to have them believe it's true.
What Chris said is exactly what I experienced.

Harold

I must admit i had the same problems with my first trial,i,ve alloyed my gold filled down with more copper but still have 7% zinc in the bar which im sure will cause problems.The basis of cell refining is high purity of the metal to be recovered whether its gold,silver or copper as the other elements present foul the solution eventually :evil:

 

[samuel-a]

wow... thank you for the vote of confidence...

listen, you guys are the only viable source of information that i was able to find about copper recovery (and PM's), information that covers all of the parameters, without missing a bit.
i did researched and trying to understand as much as possible before i started with this project and upload it in order to perfect it to the known standarts and not to re-invent enything.
i guess the info was pulled from someone's ass, but not mine... 8)
in all of the sources there was no info about: , electrolyte concentration, A:C ratio, working power and and temp', effects of more reactive metals, additives to the solution etc.

i'm now awar of the improvments that need's to be done, but have more questions first as i'm not a chemist or electronics guy.
i hope that you guys find the patience to answer or to reffer me to sources. pls bare with me.

1. in the link you (GSP) added to your post there is a common furmulation of the electrolyte and working conditions, is this universal formula or should be changed according to the type of alloy of the anode?

2. how does one can know the amount of pentahydrate (CuSO4.5H2O) in the solution ? or how much CuSO4 crystals sould be dissolved?

3. by Anode to Cathod ratio, i take it that you mean the ratio between the surface area of the two...?

4. how can one produce a DC power supplay with a constant current and changing voltage? im no electrician but this dosn't sound right to me... maybe vise versa...?
let's say i have anode and cathod in 2:1 like you mentioned, anode = 50 sq.in. and cathod 25 = sq. in. what will be the favorite voltage and current?

5. how can one produce 0.2-0.5 Volts and >10 Amps? which machinery can do that?

thank you very much.
SAMUEL

 

[Barren Realms 007]

This might help you on #4 & #5. butcher hasmade some good posts on this subject.

Posted by butcher
I will try to explain something best I can.
two light bulbs, or resistor's, or resistive loads (electrolytic cells) etcetera.

here's a rule, two risistors wired in serie's (in line end to end) the current through them is the same, but the voltage devides, lets use car headlights here for an example,
if we wire one to the battery the resistance of the lamp heats up giving light, this light will be bright it will pull ~ 55watts of power from the battery, so 55w/12V=4.58amps,(the watts are heat).and resistance would be about 12V/4.58A=2.6 Ohm's

now we wire two of these 55W lamps in series,(end to end),
---O---O---
hooking up to 12volts, now the resistance of these lamps add up to a total ohms to 5.16 ohms, so 12V/5.16 Ohm =2.3 Amp's , this 2.3 amps is the total amperage of this circuit, and is the same through both of these headlamps,(remember rule above two resistors in series current is the same) , and since they are in series,and the exact same resistance, (if different resistances this would change),each lamp is burning up half of the 12 volts so 12V/2=6volts, and these headlights are half as bright, (if we tapped a wire in the middle of these we could get 6volts to ground), now since these lamps are running at 6Volts and are pulling 2.58 amp then 6V X 2.3A = 13.8 watts each lamp, and 27.6 watts for both lamps(heat).
notice how we can get lower voltages, or change the current through the lamps, this could have been two plating cells in series, or a plating cell and a light bulb in series, or a resistor or varible resistor in series, now you'll have to concider an electrolytic cell's resistance will change throughout running it, as electrolyte and other conditions make varibles in your circuit.

now here's another rule, resistors in parralel the current devides but the voltage is the same.
---O---
---O---
these are wired side by side (how your headlight's are wired in your truck)
if using these same headlights for this example the each pull 12 volts from the battery (rule voltage the same) but the current through these devide, so each lamp pulls 4.6 amps from battery, this total amperage pull of this circuit both lamps is a little over 9amps, so from this if we had two cells in parallel, or a resistance and a cell in in parallel, we could run two cells at the same voltage, and as long as the resistanes stayed the same in the cell (it won't), the current would devide between them.

if you are doing any electroplating I feel learning some basics electric would be a must get information on OHM's law (used in calculations above) and also resistor theory to start with. it would help you with electrolisis to understand principles also.

we can change the voltage and amperage of circuits or rewind transformers to change voltage at Will.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=59&t=6096&p=53385&hilit=bulb#p53385

http://www.goldrefiningforum.com/phpBB3/search.php?keywords=bulb&terms=all&author=Butcher&sv=0&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

Hope this helps.

 

[butcher]

Power supplies can be built for constant voltage and a variable current, or they can be built for a constant current and variable voltage, an example here lets look at battery chargers, a lead acid battery charger uses constant voltage, the current will vary (as the battery cells resistance changes), the amperage or power is limited by the size of the transformer, on the other hand we have a nickel cadmium battery charger they have a constant current and the voltage varies,

Both of these will be very similar in design with a few minor differences.

As far as building a supply with a certain voltage output we can pick the transformer, or rewind the secondary winding on a transformer, remember the size of the transformer determines current it is capable of supplying without burning up, wire size is also part of this picture, the turns of wire in a transformer determine what voltage it will be, another way to change voltage is with an auto transformer or variac, these have a moveable tap on the transformer winding and can be adjusted, these are usually wired in to adjust the primary voltage of the step down transformer,

Current can be limited using a resistor, these can be several and tapped or switched in the circuit, to change currents, a transistor circuit can also be made to regulate the current, a trick is with using a light bulb in series, these will not only limit the current with the lamps filament resistance but also have an added benefit as an indicator of the current in your electrolysis cell, or circuit, and will also protect your power supply from short circuits, you can short out the circuit and the light just lights full bright, this is a trick I use for troubleshooting problems in electronic circuits,

Off track here say you have a problem in your old truck something in the head light circuit is shorted out, you are having a time trying to find it, every time you put in a new fuse and turn on the lights the fuse blows--- pull out your bag of tricks wire a light bulb across the fuse holder, pull on the light switch, as long as the circuit is shorted, this lamp across fuse terminals will be lit when you remove the short the light will go out, if there is only a partial short (resistance in the circuit the light will be dim, ok back to subject,

a constant voltage power supply can be made by limiting the transformer size , but for better regulation will need to be done in the circuit with a voltage regulator, or transistor circuit.

An electrolysis cell will need a filtered direct current, diodes or bridge rectifier and large filtering capacitors.
Power supplies are easy to build, but if you don't know how, it would be a daunting task, power supplies are in about everything electronic and are all around us, and if I did not know how to build them, and did not want to spend high amounts of gold on one I would take one scrapped from another piece of junk or modify one already built, also cells can be modified to fit a supply, first you will need a specification for your design and work with that, for a small cell a battery charger, and lamps or resistors will work, also batteries are one of the best regulated direct current sources there is, a battery charger here will keep it going,

 

[Oz]

Samuel,

Just a thought here, and it may be a non-issue. You mentioned that the pins you melted were free from iron and consisted of I believe copper, nickel, and gold. To get “pins” that were sure to be free of iron did you perhaps choose pins that make spring type connections like in computers that grab and hold cards? The reason I ask is because these are made with beryllium copper, the dust of which is a serious health risk as Harold can attest to with OSHA requirements to machine it.

So beyond throwing it out there for those that do not know about the dust hazard of beryllium copper, I am curious if anyone here knows what hazard there is or is not in melting it and what does it do in a copper cell with dilute sulfuric such as you built.

 

[qst42know]

So beyond throwing it out there for those that do not know about the dust hazard of beryllium copper, I am curious if anyone here knows what hazard there is or is not in melting it and what does it do in a copper cell with dilute sulfuric such as you built.

Fumes from a beryllium melt are also a hazard. This is a deceptive problem not all exposures will result in health problems but some individuals can be sensitized by casual minor exposure. Very dangerous stuff.

http://pubs.acs.org/cen/80th/beryllium.html

 

[samuel-a]

thank you very much barren and butcher for the electrical info.
i just might put my hand on a rectifier that can work 0-15 Volts... but has a max of 3 Amps.
i'll can give it a go next weekend and see if there any effect of a lower voltage .


Oz, yes, you are correct, this are mostly pins from mother boards , the ones that used to in the plastic slots to hold cards and only partially plated.
melting them produced a lot of smoke so i used a dust mask and a fan to blow everything away from me.
about the beryllium , i don't know for sure, but i think it's higher on the EMS then copper, which mean that it's probably goes in to solution, like zinc does.
can some one confirm that?

about the dust, they don't really create dust when plunking them out....
i twist back and forth the entire plastic casing until they snap in the bottom.

 

[goldsilverpro]

samuel-a,

1. in the link you (GSP) added to your post there is a common furmulation of the electrolyte and working conditions, is this universal formula or should be changed according to the type of alloy of the anode?

The formula I gave is below. Although I've used very similar formulas myself, I got this one from the internet. It was used by one of the major copper refiners. This formula is ideal. You may be able to stray a little, but why would you do that? It's very easy to make this up as it is written. You might try running at room temperature (at least 70 F), though.

I would suggest you use the quantities of CuSO4.5H2O and H2SO4 as listed. The Cl- is very touchy (an excess will cause problems, although I don't know exactly what these are) and it figures to only using about 0.05-0.10 ml (1 to 2 drops) of HCl per liter of solution. The Cl- helps with the anode dissolving uniformly, I think. If you use tap water, there's probably enough Cl- in it already (with some tap water, though, there may be too much). Therefore, I wouldn't add any extra. The thiourea and bone glue are grain refiners and they produce a smoother cathode deposit. Without them, the deposit will be more nodular. If the deposit is OK without then, don't add them. All in all, you may be fine with just the copper sulfate and the sulfuric.

With just the Au, Ni, and Cu in the anode, it should work fine. I am almost 100% sure that the Ni won't deposit and cause problems at that H2SO4 concentration. I have never tried to run this solution with Ni in the anode but, when the pH is reduced in a standard nickel sulfate plating solution, the cathode efficiency (amount of nickel deposited per amp-min) dramatically decreases. At some point the Ni ceases depositing altogether. A problem with the nickel could be that, if it doesn't plate, it's presence could decrease the cathode efficiency of the copper and could therefore possibly increase the amount of copper in the solution. I don't know this for sure.

If you throw other metals into the mix, like Fe or Zn, I guarantee you'll soon have problems. Not with the dissolving but with the deposit. There's no variation in the solution makeup, that I know of, that will solve these problems. In thinking about this, there may be some sort of chelating agent that could be used to tie up everything but copper in the solution, but I doubt it. A membrane can be used as a separator to eliminate the cathode deposit problems.

With few exceptions, when plating, it's usually best to start out and maintain the ingredients and the operating parameters at about the middle points of the ranges given.

CuSO4.5H2O = 100-160 g/l
H2SO4 = 180-250 g/l (I calculate this as about 10-14% conc. H2SO4, by volume)
[Cl-] (added as HCl) = .02-.05 g/l
Thiourea = .0001-.0005 g/l
Bone glue = .0001-.0010 g/l
Temp. = 55-65 C
Cathode Current Density = 130-170 A/m2 (12-16 amps/square foot = 0.083 - 0.111 amps/square inch)

2. how does one can know the amount of pentahydrate (CuSO4.5H2O) in the solution ? or how much CuSO4 crystals sould be dissolved?

In a standard acid copper plating bath, which contains the same ingredients, the H2SO4 is first titrated with a NaOH solution and an acid/base indicator. Then the specific gravity of the solution is measured. From a chart, the CuSO4.5H2O can then be determined.

I would probably use CuSO4.5H2O (blue vitriol, bluestone) for makeup. I guess you could use anhydrous CuSO4 but it's probably more expensive. If you use CuSO4, only use 64% as much.

3. by Anode to Cathod ratio, i take it that you mean the ratio between the surface area of the two...?

Yes. When calculating this, only consider the surfaces of the electrodes facing each other. In plating, to prevent things like low anode corrosion rates, a 2/1, anode/cathode surface area ratio is usually used. If you do stray from this, it's better to have a little too much anode area.

Just remember that the amperage is determined by the cathode area and not the anode area.

4. how can one produce a DC power supplay with a constant current and changing voltage? im no electrician but this dosn't sound right to me... maybe vise versa...?
let's say i have anode and cathod in 2:1 like you mentioned, anode = 50 sq.in. and cathod 25 = sq. in. what will be the favorite voltage and current?

I have never used a constant voltage or constant current power supply for any electrolytical system and never will. I have never used a battery charger and never will. I'm an old plater and will always use a continuously variable rectifier. It has a voltmeter, an ammeter, a single knob for adjustment, and a fuse to protect the ammeter in case you short the electrodes. That's it. Very simple. If you turn the knob all the way down, both meters read zero. As you turn up the amperage, the voltage automatically increases to a level based on the amperage applied and the resistance in the system. Most platers still use this type of power supply, although some have digital readouts and controls - in essence, though, they are the same thing.

5. how can one produce 0.2-0.5 Volts and >10 Amps? which machinery can do that?

Why on earth would you want to do this? Are you thinking that you could just plate out the Cu and not exceed the minimum deposition voltages of the Zn, etc. Good luck. If you can find a list of these, the numbers are based on pure systems. In reality, they are very dependent on the parameters of the bath. These can vary from hour-to-hour or day-to-day. I don't see how you could predict anything. I would just run stuff without Zn, etc., in it, set everything up right, determine the proper amps, and let the voltage fall where it may. If you have zinc, etc., use a membrane and don't plate anything out.

 

[samuel-a]

Thank you Chris.
that a first class info.

thank you very much for your help.

i'll try to keep this thread up to date.

 

[g_axelsson]

Oz, yes, you are correct, this are mostly pins from mother boards , the ones that used to in the plastic slots to hold cards and only partially plated.
melting them produced a lot of smoke so i used a dust mask and a fan to blow everything away from me.
....
i twist back and forth the entire plastic casing until they snap in the bottom.

Two things...

1. Pins used on motherboards is usually made of brass to give stiffness and the spring force necessary to make a good electrical contact. That means that you have a lot of zinc in your melt.

2. An easy way to remove the pins from the contact housing is to pull them out of the bottom. If you remove the contacts by melting the tin and pulling them off the motherboard then it is easy to pull them one or a few at a time. An alternative is to just rip the contact housing off the pins when still on the board. It takes a bit of force but then you can cut the plated top of the pins with a plier.

I have been thinking a lot about using a copper cell for gold refining. There is one argument for not being too concerned with the exact cell chemistry. Our goal isn't to produce clean copper, we want to use it for removing base metals. With that in mind, is there any reason to melt the pins? If they are only partially plated the base metals should be dissolved if it just lies in a pile on a titanium electrode. After a while the gold foils should be loose when enough base metal have dissolved and a gentle shake should make them float away and drop to the bottom. It would also eliminate the problem with microscopic gold particles that don't settle.
Ten years ago I made an experiment along these lines. I made a gold wire (didn't know about titanium then) put it in the bottom of a glass jar, added some pins on the bottom of the jar and a copper wire suspended above it. I made an electrolyte according to the data from copper baths and then applied a weak current. I pulled out 20-30 grams of copper in a large cauliflower looking lump. Very dense. The electrolyte changed from blue to green, probably from the dissolved zinc.
I never finished the experiment but I still have the jar with loose gold foil and remnants of pins. Some day I'll restart it to see if it will work.

Good luck and let us know how it works out in the end. I'm following your experiment with interest.

/Göran