Electrochemistry Silver cells in series trial run

[mike6]

Gentlemen,
It is with pleasure that I present my interpretation of the knowledge handed me by the Gold Refining Forum. I wish to thank Harold, Goldsilverpro, Frugalrefiner, and palladium for their invaluable inputs.

Would you be so kind as to examine my setup, process and figures, to enable me, with constructive criticism, to improve my skills.

It was my intention to process a mixed batch of .925, .800, and .500 silver to a .999 state as speedily and efficiently as possible.
Using GSP'S dissolution ratios, silver was dissolved in 70% nitric acid.
Silver cement precipitated using bars of copper.
Cemented silver rinsed, dried and cast into shot.
Electrolyte for cell prepared by dissolving 0.421g of .925 silver per 50/50 ml of 70% nitric acid and distilled water.
Cell volume is 5 liters (1.320 gallons).
Concentrated electrolyte mixed with distilled water in a 1:3 ratio, ie 1.666 liters electrolyte to 3.333 liters distilled water = 5 liters.
Power supply unit is rated 30A 30V.

Series setup ran for 19 hours, depositing 5509 grams of silver crystals.

This is an average deposition rate of 72 grams per hour per cell, half of what I was expecting.
I ensured that maximum individual cell voltage never exceeded 4 volts, however, cell 4, closest to the negative terminal, at times was as low as 2.9 volts.

I tested the final product( as indicated in the final picture) and am confident of my purity (.999) :roll:

Your comments would be appreciated
Mike

 

[Palladium]

Why make your cell solution out of .925 instead of out of your cemented silver (98-99%)?
Your number on yield don't add up. Maximum output is 30 amps per hr. 30 amp per hr times by 4 grams per amp hour deposited = 120 grams per amp hr. 120 grams per amp hr X 19 hrs = 2280 grams for that time period.

 

[FrugalRefiner]

Electrolyte for cell prepared by dissolving 0.421g of .925 silver per 50/50 ml of 70% nitric acid and distilled water.
Cell volume is 5 liters (1.320 gallons).
Concentrated electrolyte mixed with distilled water in a 1:3 ratio, ie 1.666 liters electrolyte to 3.333 liters distilled water = 5 liters.

It's probably just me, but I don't understand your electrolyte makeup. I'm sure you used more than a half gram of silver in your 5 liters of electrolyte.

I ensured that maximum individual cell voltage never exceeded 4 volts, however, cell 4, closest to the negative terminal, at times was as low as 2.9 volts.

4 volts may be a tad high. You could run the risk of codepositing copper.

I tested the final product( as indicated in the final picture) and am confident of my purity (.999) :roll:

How did you test your purity?

Others may be able to evaluate your deposition vs current used, though I don't know you've provided enough information for that.

Considering your anode material was cemented silver, your electrolyte looks quite blue.

Dave

 

[Palladium]

I see now! You were expecting because you ran 4 cell in series that the output would be multiplied by 4. Disposition in a silver cell is determined by amp input and is a function of an electron exchange. Amps consist of electrons and by using the amp input we can determine disposition rates. Voltage in the silver cell is a whole nother function.

 

[Palladium]

Are you dealing with leftover powder in the basket during or after running? Any problems with powder in the basket at all?

 

[mike6]

Gentlemen,
My apologies,

Total harvest from all 4 cells after 19 hours was 3049 grams. Please note that although the power supply is rated 30 Amps, it never supplies more than 12 Amps. The theory states that the voltage setting (if you wish to maintain 4 volts per cell) for 4 cells in series should be 16 volts at source, however, in practice, 16 volts provided more than 4 volts at cell number 1 and I was forced to reduce the input voltage to around 14 volts. Cell 4 often stayed at 2.9 volts. I left the current setting "floating". As time progressed, the current went as low as 9 Amps.

In the absence of knowing the actual purity of my cemented silver, I refer to it as .925

Electrolyte: 0.421g of silver to 0.5ml of nitric acid and 0.5ml of distilled water. To achieve 1666ml of electrolyte, 701.38g of silver was used. This resultant solution was further diluted 2 parts distilled water to 1 part electrolyte resulting in a 5000ml electrolyte solution. This process was duplicated 4 times to produce 20 liters of electrolyte containing 2805.52g of silver.

I tested the silver purity with my volt meter. Its a joke. seriously though, I have my product tested independently using XRF technology, and am consistently achieving .999 purity.

I am experiencing no problems with the dark grey sludge left in the anode basket. The double layer of muslin contains it well and I process it at the end of a run for re introduction on the following run.
Mike

 

[Palladium]

Why not parallel?

 

[FrugalRefiner]

Thanks Mike. My mistake in not understanding your first description of your electrolyte the first time.

Cement silver should usually be around 98 to 99% pure.

Your anode slimes could contain gold or PGMs, as well as other contaminants.

Dave

 

[Palladium]

at that concentration you should be able to process about 5 lbs of cemented 99% silver per cell before the solution is depleted. That's based on copper being the main contaminate other metals require different figures. At 98% silver those numbers drop to 2.5 lbs.

 

[mike6]

Considering your anode material was cemented silver, your electrolyte looks quite blue.

Dave, what does this mean? I cast my anode terminal ( my version of a "candlestick") out of .999 silver, as I thought it would improve the transfer of electricity to the cemented silver shot in the basket, (the anode material).
Mike

 

[Barren Realms 007]

Considering your anode material was cemented silver, your electrolyte looks quite blue.

Dave, what does this mean? I cast my anode terminal ( my version of a "candlestick") out of .999 silver, as I thought it would improve the transfer of electricity to the cemented silver shot in the basket, (the anode material).
Mike

If it were .999 fine silver your solution shouldn't be as blue as it is.

(1) Unless you added copper to the solution.

Or

(2) You washing procedure wasn't very well done.

 

[MarcoP]

Electrolyte for cell prepared by dissolving 0.421g of .925 silver per 50/50 ml of 70% nitric acid and distilled water.

Is this why the electrolyte is blue?

 

[goldsilverpro]

If I heard you right, 12 amps x 19 hrs x 4 units x 4.025 g/A-hr = 3671 grams of silver. This would be 100% of theoretical, assuming you ran at 12A. You got 3049g. That is 3049/3671 = .83 or 83% efficiency, which isn't that bad. You could probably increase the efficiency by lowering the voltage to about 3.0-3.5V per cell, thus lowering the amperage a bit, or by adding more silver to the solution.

In a perfect series circuit, 12A should have been applied to each of the 4 cells. The series hookup is the correct configuration to use, not parallel. The voltage is additive in the 4 cells hooked in series and, if there are even subtle differences in the cells, the voltage will vary somewhat in each cell. All you can do is try to make the cells as identical as you can.

If I had it, I would use sterling to make up the solution. No matter what has been said in the past about copper or no copper, I am still totally convinced that one should start the solution with some copper in it. I refuse to argue about this any more. Your silver looks good to me, although it appears to have been shotted. Do you have a photo of just the rinsed crystal?

Were it me, I would have started with 2 cells in series first, just to learn the lay of the land. It's a lot simpler than 4. Also, with 4 cells, I might occasionally remove the solutions, mix them together, filter, and then put them back into the cells. That could help balance the cells.

Another thing is the wires. They look a little small to carry 12A. Do they heat up at all? In a D.C. circuit, for 12A, to prevent heating, the cross sectional area of the copper wires should be a minimum of .012in2 - or, the Cu wire diameter should be about .08-.09 inches, for solid wire. That's based on 1000A/in2, the figure that platers go by.

All in all, I feel that things are looking good. It seems like you have done a good job.

 

[Palladium]

If I heard you right, 12 amps x 19 hrs x 4 units x 4.025 g/A-hr = 3671 grams of silver. This would be 100% of theoretical, assuming you ran at 12A. You got 3049g. That is 3049/3671 = 83% efficiency, which isn't that bad. You could probably increase the efficiency by lowering the voltage to about 3.0-3.5V per cell, thus lowering the amperage a bit, or by adding more silver to the solution.

God knows i'm not going to question your experience with silver since i learn almost all i know from you, but i have to understand if were not on the same page here. The numbers you quote would be if he was pulling 12 amps per cell which would equal 48 amps overall. I think he was only pulling 12 amps total through all the cells. His power supply is limited to 30 amps maximum! Given the limit of his power supply running at 30 amps for 19 hours X 100% efficiency would equal about 2280 grams total. Theoretically using that logic i could series wire 1,000 cells together running on 1 amp and expect to get 1,000 grams an hour? Numbers can be confusing. :twisted:

 

[g_axelsson]

If I heard you right, 12 amps x 19 hrs x 4 units x 4.025 g/A-hr = 3671 grams of silver. This would be 100% of theoretical, assuming you ran at 12A. You got 3049g. That is 3049/3671 = 83% efficiency, which isn't that bad. You could probably increase the efficiency by lowering the voltage to about 3.0-3.5V per cell, thus lowering the amperage a bit, or by adding more silver to the solution.

God knows I'm not going to question your experience with silver since i learn almost all i know from you, but i have to understand if were not on the same page here. The numbers you quote would be if he was pulling 12 amps per cell which would equal 48 amps overall. I think he was only pulling 12 amps total through all the cells. His power supply is limited to 30 amps maximum! Given the limit of his power supply running at 30 amps for 19 hours X 100% efficiency would equal about 2280 grams total. Theoretically using that logic i could series wire 1,000 cells together running on 1 amp and expect to get 1,000 grams an hour? Numbers can be confusing. :twisted:

Yes. The current goes through each cell and moves silver atoms in each one. It's the same current, just as the same water could go through four serially connected pipes. The voltage from each cell is added to the total voltage so while the current stays at 12A the voltage rises to four times when running four cells in series.

You can theoretically build 1000 cells in series but then the voltage would rise to 1000 times of one cell and I wouldn't know if I could build a 3 kV 1A power supply. At least I couldn't run it safely. So it's not a practical alternative.

Göran

 

[Palladium]

But were not talking about voltage. Voltage is the pressure that delivers the amperage. Amperage is what does the work in the cell. Voltage has nothing to do with the disposition rate, it's only the pressure at which the amps are delivered. You can only get so many grams per amp regardless of how it's wired. Output is directly tied to the electron exchange that does the work or amps. Voltage is the cause and current is the effect. You can not get more out of a system than you put into it.

 

[Palladium]

I'm starting to see some logic to the problem, but when ran in series is it really possible to use the same electron multiple times?

 

[FrugalRefiner]

But were not talking about voltage. Voltage is the pressure that delivers the amperage. Amperage is what does the work in the cell. Voltage has nothing to do with the disposition rate, it's only the pressure at which the amps are delivered. You can only get so many grams per amp regardless of how it's wired. Output is directly tied to the electron exchange that does the work or amps. Voltage is the cause and current is the effect. You can not get more out of a system than you put into it.

Göran is right. If you push one amp through a single cell, you'll get a particular deposition rate. If you push that same one amp through 2 cells connected in series, you'll get approximately the same rate in each cell, for a total deposition of approximately twice as much.

It's not a trick, and you don't get twice as much silver for the same amount of electricity. Remember that in the two cell system you'll need twice the voltage from the power supply to run both cells at the same voltage and amperage as the single cell system. Volts x Amps = Watts. You'll use twice as many watts running the two cell system as running a single cell.

There's no free lunch.

Dave

 

[Palladium]

I see what your saying now. Up until now i have only used single cells. I remember a debate a couple of years ago where Chris defended that logic and i'm just trying to get a grasp on the multiple cell theory.

 

[mike6]

Gentlemen,
Thank you for your comments to date.

Let me clarify that it is the anode electrodes that are made from .999 silver, each weighing 150 grams,(see attached picture) and not the electrolyte.(The electrolyte was made up from cemented silver shot, which in its original form was .500, and .800 silver coins)

After 10 hours, I did indeed drain all 4 cells of their electrolyte, mixed it all in a single 20 liter container, filtered, and re introduced to each respective cell.

All copper wire used in the circuit is 4mm2 ( 0.157in2), and no heating was observed on the wire or connection points.

The silver crystals in the attached picture are from cell number 4. After rinsing, they were indeed turned into shot.

I am using a bench top regulated power supply, and not a designated plating rectifier. I am able to regulate the source input voltage, but not the amperage, this value "floats" according to the internal resistances of the circuit. I determine the voltage of each cell independently using a volt meter, and reduce the input voltage from the power supply so that no individual cell receives more than 4 volts, the power supply regulates the amperage automatically, and as in the picture in my first post, at that particular time, voltage reading was 14.9 volts at 11.9 amps.