Electrochemistry Silver crystals growth speed in an electrolytic cell

[Aurumlife]

Hi guys. Im a new member here in a forum. I am currently refining some silver in a cell. My stainless bowl cell contains 2.5 of electrolyte. Concentrated to 200 grams of 999 silver dissolved for electrolyte. Running at about 1.5-1.7 amps current at 4.5 volts from power supply. Distance anode/cathode areas in a bowl about 4”, Dacron material double filter in the anode basket. Had about 1 kg of silver shot from cement silver loaded in the basket. Crystals forms normally, no anomalies (at least known to me) are not happening thru the process. I have couple of questions: 1. How much silver crystals growth ratio I can expect weekly? Cell runs 24/7. 2. is it beneficial for the sake of cutting costs of labor/chemicals to lode basket with the sterling instead (I know that sometimes alloy that jewelry items are made with are not up to 92% silver content)? In literature I was reading that refineries use anodes that are even less than 90% silver. I also heard opposite opinions, that need of replenish the electrolyte and add nitric would consume significant amount of time that would almost balance out the time/chemicals spent to refine larger batch of silver thru nitric first and cement out later to feed the cell. Advice would be greatly appreciated as I try to keep the cell operation as remotely as possible. I do this part time and only have limited amount of time for refining which I like doing and earning little extra income. Thanks in advance.

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[nickvc]

You can run sterling directly in the cell but the electrolyte will foul quicker but you can negate that by adding more nitric to dissolve some of the fine silver in your cell to increase the percentage of silver in the electrolyte to keep the silver pure that plates out.

 

[Palladium]

The amount of silver deposited is in relation to the amps put into the system. 4 grams is deposited for each amp/hr.

4 grams/amp hr X 1.7 amps = 7.2 grams per hour.
7.2 grams hr X 24 hours X 7 days = 172 grams per day or 1,209 grams per week.

Your right on the edge with the voltage. It's ok while the solution is fresh and free of contaminates, but once they start to build they will co deposit with your silver. Get better ground connections to and from the cell and at and around the anode. Any lose or weak connections act as resistors, produce heat, rob you of efficiency, and cause the voltage to rise. Fix those and amps will rise and voltage will drop.

 

[Martijn]

If I may advise: put your cell in a catch basin or make a firm stand with a round hole to keep the cell from tilting and spilling.
It's easily bumped into.

 

[Aurumlife]

What would still be your preferred method of refining method thru the silver electrolytic cell, guys? Melt the sterling material and go directly into the cell or recovering silver with nitric/sulfuric acids and them cementation on copper? What is more efficient considering all factors: time, money, volumes, etc...? Would really appreciate your professional opinions guys. Thanks in advance.


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[FrugalRefiner]

We discussed this recently in Silver Cement directly into silver cell?.

Dave

 

[Aurumlife]

I saw this post previously to I posted mine. Very helpful and informative. Ton of helpful stuff. But still would be delightful to hear what folks have to say about other things like: initial load (quantity) of silver in anode basket affecting speed of crystal growth (also whats better: more frequent small anode loads vs one full) and its correspondence to size of the cathode bowl? concentration of silver in electrolyte affecting speed of growth of crystals and need to change (frequency in days/hrs/weeks) the electrolyte in relation to cement silver cell vs sterling silver cell. Would be wonderful to hear more numbers/data after observing how these cells produced over a period of time. Basically their production rate against one another. Mine is the first try for example and its running 11th day, initially loaded with about 400g. of cements silver shot and on about 4th day of production little over 800g added. At start electrolyte concentration is around 200g

of just 999 silver dissolved in 2.5 liters of solution. Current is kept mostly 1.5 amps at 4.2-4.5 volts. Here how the growth looks now. Crystal formation seems of satisfactory quality, heavy and size, no “steel wool”

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[Gsracer]

Ok so i can give you my experience with growth speed.

As stated above by palladium AMPs is what does the work, 1 amp hour equals roughly 4 grams of crystal per hour. Anode load hasnt really had any affect for me personally full basket vs almost empty basket.

Now what affects how much amps you can run is the cells resistance. Things that will lower resistance would be. Again this is from my experience. Anyone feel free to correct of course.

1. Anode to Cathode spacing ( the optimum is 4-4.5 inches ive read)
Problem is if you shorten the distance you run the risk of shorting the cell out because the crystal will grow quickly to the anode.
2. Anode to cathode ratio, the large the anode is in relation to the cathode the lest the resitance will be. I don't recall the exact ratio, however in my first 2L cell i had an anode basket that was huge in relation to the cathode and i could really crank the amps through it, problem was i had to be constantly on top of it and i couldn't run it over night.
3. Electrolyte concentration, the higher the silver content the lower the resistance, personally i run 300 Grams of silver in my 2L cell, i end up with about 400 grams by the end of 2 week run as i top off the electroylte from evaporation.
4. Simple thing, holes in the anode basket, if your basket is small then open more holes in it and this allows for more amps because of less resistance.


My last run which i harvested on monday was 11 days exactly 282 hours. I keep a log of observed volts and amps through the day and adjust it to always be at between 1.43-1.6 amps.
At the start it was running 1.92 volts 1.43 amps by the end it would take 1.5 volts for the same 1.43 amps. If i cranked the voltage to 3.5 volts i would get almost 4 amps but the cell would short out in minutes. You can literally watch the silver grow at that point.

Anyway after 11 days (282 hours) i got a yield of 1583.3 Grams which works out to 5.6 grams an hour. When you further do the math 5.6 grams per hour at 4 grams per amp works out to 1.4 amps which is exactly where i would expect to be.

Heres some pics

 

[Aurumlife]

I appreciate it. Some valuable info there sir and a great result of yours. What I suspected that my cell lacking also is hole sizes and quantity at my anode basket. I also will remake the connections to cathode. I will make changes and post some pictures once this cell would fill up and be cleaned up. Thanks again for the valuable info.


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[Palladium]

All the Science and experience involved with producing these pure crystals.
If i would have taken the time to study each little aspect of the science, then i never would have had the time to invent the cell in the first place.

It was a car jacking in progress! :lol: :lol: :lol:
Still is! :mrgreen:

 

[Aurumlife]

Well I know what you mean Palladium, but you guys also take notes, collect data throughout the years of refining. Im just getting started, thats why I was wondering. I didn’t expect scientific article. How do you process your silver personally. Do you separate copper chemically first of you run sterling directly thru the cell? What is your preferred method? I get it that lots of silver you guys process from gold refining operations (inquartation)so that is automatically be a cement silver. Im asking about silver materials that are refined separately from any gold refining.


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[Gsracer]

Here is a spreadsheet i made for my self a while back from learning from one of Mr. Palladiums YouTube videos.

Here you can see why its not preferential to run just sterling, the electrolyte

The editable fields are Electrolyte quantity, Dissolved Silver quantity and Safety margin.

According to palladiums video copper will coprecipitate at 50gl silver concentration. With sterling the main contaminant is copper. So how much copper you introduce will displace silver in your electrolyte at a ratio of 1 Gram of copper displacing 3.4 grams of silver in solution.

So knowing that, in my 2L cell for example with 300 grams of silver in the electrolyte i know that i can introduce 58.82 grams of copper before i risk coprecipitation. When you figure how much sterling at that level you can run in the cell you will see that it only takes 25.2 troy ounces of sterling before the electrolyte is depleted. However for 98 pure cement silver which is relatively easy to get to with good rinsing techniques, you can process 94.6 troy ounces almost 4 times as much. Conserving nitric time etc.



In the end its probably a wash for nitric usage , but cleaning the cell and changing anode baskets is a pain for me so. Yea.

Here's the spreadsheet if you want to play with the numbers, you can edit electrolyte qty, silver in the electrolyte quantity, and safety margin just in case you want to be sure. Using the numbers i learned from palladiums vid, i have never had an issue.

However it is worth noting that this doesn't account for platinum , or palladium, or other contaminants.


View attachment Silver Cell Electrolyte Worksheet (1) (version 1).xlsx

 

[Aurumlife]

That is some great info! Thanks a lot!


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[Aurumlife]

Here are the results. Please comment guys. Feedback is highly appreciated and valued.

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[Gsracer]

nice looks great!

How many hours did you run the cell? All 3000 grams where from the same run?

 

[Aurumlife]

Its minus the dish. The weight of silver is 1939.7 grams. Ran for about 16 days. But it was running for first four days with anode basket about 1/3 full till I finished with the rest of the silver cement rinsing and melting and filled it to the top.


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[Aurumlife]

By the way. What does running the crystals thru the second time accomplish? I heard that Kadriver does it for example. Isn’t purity enough at the first run and is industry standard?


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[Gsracer]

Thats a good result id say. Sreetips runs it twice to make sure its 4 9s fine, in case some impurity followed the crystal. Some people do, 3 9s fine is more than good for me, even though it regularly comes out 4 9s. If you followed the process correctly and where clean with your procedures i dont think youd have a problem.

 

[Aurumlife]

Well I’ll tell you a few things before it’s going to actually be essayed: nothing went thru the filters (Dacron material), original material was rinsed well from nitrates of other metals. My electrolyte color was just slightly pale green/blue after I was done with this run. And I have a good amount of slimes in the basket. I’ll post some pictures later.


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[Aurumlife]

Portion of silver crystals melted into beautiful bars. I greatly appreciate all the comments and very helpful information guys. Going to do Wohlwill gold refining cell soon. Will post some pictures from process and results.


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