Question about running cells in series

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Kaiser613

Active member
Joined
Feb 2, 2020
Messages
35
Hello, I had a question about using electrolytic cells in series, I'm trying to design a cheap first cell for myself, specifically put together for electrowinning copper, to collect the values in the minor constituents ( feedstock material In mind is the non-ferrous metal portion of ball milled low grade circuit boards, after melting out solder portion in hot pot, and possibly removing nickel with Monde process, more on that later) which in this case would mostly consist of zinc (from brass) silver , beryllium , and (if not removed by Monde) nickel, chromium, molybdenum, tungsten, ect., From what I've read in copper cell threads, separating copper fromother base metals is dependant on very low controllable voltage, under 1v, now here's where my question comes in

Trying to find a cheap adjustable power supply that goes below, 3v AND can handle a KW of load (that's the scale I'm planning for my purposes) is frustrating me so I was wondering if placing multiple cells in series from a 6v or 12v fixed voltage power supply would be fruitfull solution. My concern is would the voltage be
A.evenly distributed or
B. would each cell receive less voltage that the last,
would the resistance of each cell effect this?
I'd like to be able to say attach 24 cells in series to a high amperage 12v power supply which by my math should give me .5v across each cell, then when it comes time that I need to adjust the voltage (up) in order to fraction out a different metal (onto a different cathode obv.) I could simply remove one or more cells from the series.
But if voltage doesn't divide even like that then there would be a spectrum across the series and anodes could be moved down the line the fraction

Somebody who understands electrons better than me please explain

I also have questions about the Monde process but that belongs elsewhere
 
In theory that should work. Practically not so much. You will still have to monitor each cell in a timely manner. As long as the cells stay balanced, everything will be fine. If you have a consistent feedstock, added at even times, you should have little problem. In other words, if each cell is fed evenly, with the same potential, then the deposition and rate of depletion should remain the same.
Try it, you can only go crazy trying to keep-up.
 
So if I understand you,

If all 24 cells were identical (same surface area of anodes/cathode available, same distance between -odes, same concentration of electrolyte, ect. Then each would run at an equel .5v potential between each set of -odes. But then as the cells run over time, the geometry of corrosion and deposition will change the available surface area differently in different cells, causing ?

What am I balancing exactly? Resistance? I'm looking at this relative to resistors in a voltage splitter (which I still don't 100% understand but I have the basic principle; two resistors of different resistance causes output voltages to be split relative to resistance) so as -ode surface goes down (or electrolyte conductivity goes down) restance should go up? Does that cell experience increased or decreased voltage ( also wouldn't amperage density go up in this cell?)
 
Kaiser613 said:
Hello, I had a question about using electrolytic cells in series, I'm trying to design a cheap first cell for myself, specifically put together for electrowinning copper, to collect the values in the minor constituents ( feedstock material In mind is the non-ferrous metal portion of ball milled low grade circuit boards, after melting out solder portion in hot pot, and possibly removing nickel with Monde process, more on that later) which in this case would mostly consist of zinc (from brass) silver , beryllium , and (if not removed by Monde) nickel, chromium, molybdenum, tungsten, ect., From what I've read in copper cell threads, separating copper fromother base metals is dependant on very low controllable voltage, under 1v, now here's where my question comes in

Trying to find a cheap adjustable power supply that goes below, 3v AND can handle a KW of load (that's the scale I'm planning for my purposes) is frustrating me so I was wondering if placing multiple cells in series from a 6v or 12v fixed voltage power supply would be fruitfull solution. My concern is would the voltage be
A.evenly distributed or
B. would each cell receive less voltage that the last,
would the resistance of each cell effect this?
I'd like to be able to say attach 24 cells in series to a high amperage 12v power supply which by my math should give me .5v across each cell, then when it comes time that I need to adjust the voltage (up) in order to fraction out a different metal (onto a different cathode obv.) I could simply remove one or more cells from the series.
But if voltage doesn't divide even like that then there would be a spectrum across the series and anodes could be moved down the line the fraction

Somebody who understands electrons better than me please explain

I also have questions about the Monde process but that belongs elsewhere
Click to expand...

Running 3v and 1 KW means 333 AMPS in the circuit.
Running 1v and 1 KW means 1,000 AMPS in the circuit.

If someone gets electrocuted, one-tenth to two-tenths of an amp is usually fatal.

If you don't establish some industrial-strength safety precautions, you're risking property damage and death.

-- Thipdar
 
I think it would be really useful for you to use and control a basic cell/electrowin cell before jumping straight in to the involved stuff. That way you'll have a much better handle on what you are trying to achieve but more importantly HOW.

Build a simple one and use the voltages/ampages detailed all over the forum. To be really I honest I do a fair bit of work these days with this kind of stuff and I've never approached anything like the currents you are looking at.
 
Hmm, I had considered the high amperage involved, and am more than carefully around electricity, but that doesn't sound great, the only reason i said I'm scaling for a KW of load is because Im not expecting a considerable return of "precious" metals so the utility of the cell is really the volume of base metals it can process

The situation I'm in that this makes sense for me, is that I'm a mid level scrap handler who trying to expand into electronics, local buyers pay litterally garbage prices for any electronics, even ram cards and processors are valued less than a dollar a pound, and I'm 1000 miles from BoardSort so it's gonna take an ltl (if not ftl) freight shipment to justify sending in gold content boards, but the low and mid grade boards simply aren't worth shipping anywhere and the yard down the street pays less than steel for them, I've planned to instead set about milling and refining then, the electrolytic cell would be last step in the process

Without it, the feedstock that would've gone into cell, would sell as brass as best abt $1.20/lb (if not lower, plus is finely granulated and may be rejected or downgraded by a scrapyard for such, the cell would also consolidate the granules into cathode rods without having to have a foundry, hopefully) so the cell would upgrade it to #1 (or better) copper plus recoverable zinc and other minor contents

I didn't consider anything I was planning to be "the hard stuff" but if that's what folks here think they're probably right, now that you all know my situation what would be a better solution for me?

For example does anyone know what I could use as a power supply for my low voltage needs that I could pull from scrap or salvage from a cheap appliance?
 
And I know a lot of people are like "why bother with the low grades?" Throw them away, sell to local yard for 2¢ ect. But they represent a larger bulk of the boards from generic, random, all sorts electronics, and collecting enough gold content boards to make worthwhile is going to necessitate indiscrimantly collect and breakdown large quantities of all kinds of electronics, (most of the boards I encounter get left behind or throw out cuz they're tied up in something like a printer, that isn't immediately saleable and labor intensive to dissemble, plus hoarding gold content boards to ship to buyer, means a long term investment of space, time, and labor until I can reach a volume worth shipping, interim income from low grade boards become vital to keep up with labor
 
I'm right there with you on the low grade stuff.

If you get enough of it then sure, max out what you can get.
 
I cobbled together a rough but fairly concise process (on paper) that should work for me, may work for others and is probably pretty close to how industrial board processors handle this material, except I'm seeking to do so with the least expense in not only labor but also equipment overhead (so exactly like industrial, lol)

1. Rip off largest, heaviest components with hand tools, in this grade that means , aluminum extrusion heatsinks, aluminum can capacitors, transformers, inductors, and connectors and plugs, the 2 aluminum products, can be sold locally basically as is,(I haven't attempted selling the capacitors as Al breakage yet but im only expecting minimal resistance from local yards, my main buyer has their own breakage mill so theyre pretty tolerant) the transformers inductors and connectors (by which I mean only the largest, typically rca and coax onboard connectors) can all be milled in house, I've been using a 2.5hp electric chipper shredder for this and for this specific waste stream it works pretty well, but anything larger and it bogs down, I'm planning to remove the motor and use it to drive a much simpler (and hopefully more efficient and tolerant) ball mill, to process whole boards. Which the copper from these larger components is heavy enough that it wads together and is easily removed from the remainder metal portion which is almost all brass, minor steel contam for the magnet
2. Mill whole boards to pass, maybe an 1/16 inch screen, by that size 99% of metal should be liberated, even the copper/brass wire inside small resistors, I think, have to test. It's going to be milled too small for an air separator, so I'll be putting together a shaker table (also called a Miller's table)0to separate out nonmetal portion with recirculating water
3. Separate ferrous portion with magnet (I have electromagnets from magnetic drill presses, was planning to build a mag cross belt once I find some conveyor material) this could also be done before the shaker table, that might work better
4. Place non-ferrous metal portion in casters hotpot to melt and remove solder portion, may have to rig some mechanical means of "pressing" liquid solder from "sponge" of high melting metals, depending on solder content
5. Monde process https://en.m.wikipedia.org/wiki/Mond_process
To remove nickel, and may potential remove a number of other valuable metal like chromium. The chemistry and mechanics seem fairly simple, it does involve some extremely toxic chemicals but only as a transitional state, the nickel carbonyl gas that is, it isn't released as a waste, it's reduced back to CO by the end, other than that it sounds like a syngas or woodgas breathing Mercury still, there's more going on chemically but if done properly, it won't matter
5. The last step would be the electrolytic cell
 
First of all, forget about the Mond process, nickel carbonyl is acutely toxic, one mistake is all it takes and as wikipedia noted https://en.wikipedia.org/wiki/Nickel_tetracarbonyl
Nickel carbonyl may be fatal if absorbed through the skin or more likely, inhaled due to its high volatility. Its LC50 for a 30-minute exposure has been estimated at 3 ppm, and the concentration that is immediately fatal to humans would be 30 ppm. Some subjects exposed to puffs up to 5 ppm described the odour as musty or sooty, but because the compound is so exceedingly toxic, its smell provides no reliable warning against a potentially fatal exposure.
Click to expand...

Just don't do it! Anyhow, you need to have the material in a fine powder form for the gas to be able to react so it's impractical even if it was safe, which it isn't.

Just do as the big boys, let it concentrate in the electrolyte and get it out by crystallization of the nickel sulfate.

Göran
 
Thipdar said:
Running 3v and 1 KW means 333 AMPS in the circuit.
Running 1v and 1 KW means 1,000 AMPS in the circuit.

If someone gets electrocuted, one-tenth to two-tenths of an amp is usually fatal.

If you don't establish some industrial-strength safety precautions, you're risking property damage and death.

-- Thipdar
Click to expand...

Lethal amperage is even less than that if you get it across your chest, stopping the heart. But you need a high voltage to push a high current through a body.
A truck battery could easily deliver 1000 amps if you drop your wrench across the poles. Electric welders could easily deliver hundreds of amperes continuously, but both are considered to be safe to handle without any safety equipment as the voltage is so low.

The only danger from a transformer capable of delivering 1000A at 3 volts is explosion and arcing if you short circuit it, it's still 3 kW of power.
There are no electric shock hazards on the low voltage side as long as you keep away from open hearth surgery where a normal AAA battery could kill you.

For someone that have worked with electricity in one form or another for the last 50 years, electrically it's safe as long as you don't cross the wires without a load in series.

Göran
 
Thanks for your reply, I had questioned that aspect of the high amperage warning, I thought extra-low (even fractional) voltage would negate a lot of the danger, that said, any cell I build will have pretty strict safety precautions , not only for myself and anyone who understand what it is, but I'll also have to place some kind of enclosure around it to protect anyone ignorant of its purpose from walking up and say.. dipping they're hand in it.
 
My recommendation is to just set up a small cell with a variable power supply capable of deliver just a few amperes. Adjust the size of your anode and cathode to match the current density for a copper cell. Make some electrolyte and play with it a while using pure copper anodes. This will give you an idea of how a working cell might behave and problems you might run into like polarization, uneven deposition, uneven erosion of the anode...
You will find out that even a simple cell is hard to control.

Next step is to make some of your anodes based on the scrap you plan to run. Now the difficulty to control the cell is increased. If you doesn't get rid of the base metals you will foul the electrolyte in no time. The big boys are melting electronic scrap in large furnaces and then blows oxygen through it. Zinc is boiling off while base metals like iron, lead, tin and aluminium ends up in the slag for further treatment. The raw copper is mostly copper with a bit of nickel and trace amounts of precious metals. So the anodes they run is over 95% Cu. The electrolyte is constantly tapped off and purified from nickel, then returned back as fresh electrolyte. By keeping close track of the parameters of the cells they can run hundreds or even thousands of cells in series.

Resistance is just what it sounds like, resistance to let the current through. The higher the resistance the higher the voltage needed to let a certain current through. Since current is the same thing as electrons the current going into in any point in a circuit is equal to the current going out. Look at a cable, at any point the current coming in from one side is the same that continues out on the other side.
If you connects several cells in series then the current going through the first cell is the same as the current going through the last one. The only thing that can vary is the voltage over each cell.

Le's do an example. We have six ideal cells that have the resistance of 2 ohm and we have a power supply capable of deliver 12V and 100A.
If we connect all the cells in series then the 12 V will split up evenly since the resistance is equal, giving us a cell voltage of 12/6 = 2V. The resistance is 2 ohm so the current is 2V / 2 ohm = 1A. So even while the power supply is capable of deliver 100A, we will only draw 1A.

We could do the calculation in another way too, just add up the resistance in series, 2x6 = 12 ohm. The power supply delivers 12V so the current is 12V/12 ohm = 1A. The individual cell voltage is 1A x 2 ohm = 2 V.

Now something happens with one cell, the resistance goes up to 4 ohm. Maybe the material of the anode is a bit different. The easiest way to calculate what happens is to add the resistances togeteher again, 5x2+4=14 ohm, so the current drops a bit to 12/14 A. The cell voltages changes accordingly, 2 ohm * 12/14 A = 12'/7 V = 1.71 V and 4*12/14 = 3.42V
The voltage increased in the cell that got a higher resistance, the voltage drops in the other cells and the current drops for all cells.
In the same way if we get a lower resistance in one cell, the voltage and current increases in the other cells while the voltage drops and the current increases in the faulty cell.

So, yes, you can run several cells in series but you need to monitor the cells closely and control the parameters.

I spot a number of other problems in your plan. For example you won't be able to just heat the source material and squeeze out the lead and tin. It will alloy and mix with the other stuff.
In theory a lot of things will work, but only if the theory is too simple. A theory will get more and more complex when you add in real world stuff and when it matches the real world it will show you that there are a lot of problems that the initial simple theory didn't show.

Göran
 
As Göran stated, low voltage at high amps is not as dangerous as high voltage low amps. Realize that low amps doesn't mean much since it is relative to what the source could provide.

Low voltage high current
Think about how many times you connected a 12 volt (or even 6 volt back in the day) car battery to the negative and positive terminals. A 12 volt car battery could theoretically be able to deliver 1,000,000 amps, but that would not change the fact that connecting the terminals together won't shock you. There will be a spark if you connect the battery backwards, but you won't get electrocuted or electrically shocked. You may burn out components in the car, get burned from the sparks or exploding battery, or get shocked (meaning, taken by surprise), but you wouldn't get electrically shocked.

High voltage low amperage
Self generated static electricity is high voltage (say 25k volts) but very low current (just small amount of electrons). No chance of dying there.

Increase the electric potential (voltage) and increase the risk of getting shocked. Even 120 volts at 60 hertz (standard source voltage in US residences), although can electrically shock a person, unlikely it will kill. Step up the potential to 480 volts, different story, that can easily kill.

There are always exceptions to what I said above, but in general with respect to the application the OP was referring to, low risk of getting shocked and even a lower risk injuring oneself. Of course, there are folks out there that do not practice any safety, so I guess anything is possible.

For what it is worth, I fiddle around with 15k volt power supplies that can each deliver 60 milliamps sustained. That can absolutely shock the heck out of you. When I operate the supplies, work on a non-conductive surface with non-metal shanked shoes, never use two hands and use a deadman switch (a switch that I have to physically press down and hold in order to operate the supplies). Using the deadman switch doesn't mean I'll live, it just increases the chance the power to the supplies will be cut and increases my chances of survival somewhat because the source would not continue to flow through me causing more damage to organs, etc.
 
I've moved the rest of the noise in this thread to the Debates and Discussions section of the forum. If anyone feels a need to continue the argumentative posts I moved, you can do it there.

Dave
 

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