Silver Electrolytic Cell Volume

[4metals]

I've had excellent results using a PVC tape to wrap the cathode connection down to the plate. McMaster Carr sells it.

 

[metatp]

I'v seen that coating be porus. This would allow your crystals to grow thru it.

They don't appear to be growing through, but growing up the side. I can peel it off and it started from the bottom.

 

[Barren Realms 007]

I'v seen that coating be porus. This would allow your crystals to grow thru it.

They don't appear to be growing through, but growing up the side. I can peel it off and it started from the bottom.

Now that's wild. 8)

 

[metatp]

Yes, be sure to maintain a 4" anode to cathode spacing. Also the cathode should be no more than twice the area of the anode

Can you tell me the significance of the cathode to anode area ratio? What happens when the anode is larger than the cathode?

Thanks,
Tom

I never received an answer to this question, so I tried it out. It appears that with an anode being larger than the cathode leads to growing silver wool like balls (marble size). I did not get the branch like crystals unless I reduced the gap between the anode and cathode or increased the voltage. The crystals appear to be pure, but may require more rinsing. Has anyone else seen this same results? When I reduced the anode size, I got the typical crystals. Does anyone think that we can make denser crystals as we reduce the anode size?

Thanks,
Tom

 

[lazersteve]

Current flow through the cell is a function of the cell resistance which is function of the electrolyte, cell spacing, and the ratio of the areas of the anode and cathode.

Steve

 

[Westerngs]

Small amounts of tartaric (1g/l) will help make more dense crystal. However, don't overdo it on the tartaric as it will cause anode slimes to migrate out of the filter bag and deposit on the crystal.

It is really not necessary to use tartaric if you keep the Ag concentration of the electrolyte >60 g/l.

Also, if you add CU(NO3)2 to the electrolyte to about 30 g/l, it will help the conductivity and help the Ag plating. If you keep the voltage to under 3 volts you should not co-plate much Cu and your Ag should still be at least 0.9999 pure

 

[goldsilverpro]

Good to see someone agree with the addition of some copper. I also started with about 30g/l copper. I was running 12, 30 gal Thum cells.

 

[rusty]

I've had excellent results using a PVC tape to wrap the cathode connection down to the plate. McMaster Carr sells it.

Shrink tube available at your local automotive parts store. Comes in pre-cut lengths or rolls.

[youtube]http://www.youtube.com/watch?v=hnWhXVFSN7g[/youtube]

 

[BrewCity]

I could use a bit of assistance with my first silver cell.

I've recovered silver from approximately 1855g of Sterling (a few small .8 pieces in the lot). Cementation and silver shot creation appears to be right on schedule. I created quite a bit of electrolyte and made a silver cell as seen in kadriver's YouTube videos (outstanding work, Sir). I'm still working to perfect my bar pouring skills, so for now I'm just using a silver round as my anode shoved into the cemented silver shot (anode basket). My stainless steel bowl holds 2.5L and currently has a silver density of 166 g/L.

The problem is my power supply is running at 3A at about only 2V. If I increase the current, I can reach 3V, but I'm afraid the current would be unexceptably high (and create impure silver perhaps). I understand it should be only about 1A @ 3V. I tried increasing the electrolyte silver density 150g/L to 166 g/L, but it didn't appear to have much effect. Can anyone point me in the right direction to get my silver cell on track?

I appreciate any guidance you all can offer me.

 

[Palladium]

If you just started the cell it will need about 24 hours to acclimate. Push your voltage up to about 4.1 volts and as the cell levels out the volts will drop.

 

[BrewCity]

Thank you!

Okay, so I have changed out my 3A fuse to a 10A fuse. I drove the power supply up as far as it would go under the present conditions. I am now running 5.02A at 2.4V (I'm giving her all she's got, Captain). After only 10 minutes, I have white, crystalline silver formation along the scratches of the stainless steel bowl. I will continue to monitor closely to see if/how much the amperage and voltage change over time (adjusting voltage upwards as this setup permits).

Can I just point out how difficult it was to find truely stainless steel bowl? Goodwill, Target, Walmart - all magnetic. I ended up just permanently borrowing our kitchen bowl from 10-15 years ago. I replaced it with one of the magnetic bowls I found in the store. It's a shame that a stainless steel stamp doesn't really mean much anymore.

 

[Palladium]

If the max is 5 amps and your only pulling 2.4 volts then you're in good shape. Amps is what produces the silver, not the volts. Higher voltage leads to co precipitation, but will not produce more silver unless the amps are able to rise with it. You're pegged out now so a higher voltage will do no good.

 

[FrugalRefiner]

Can I just point out how difficult it was to find truely stainless steel bowl? Goodwill, Target, Walmart - all magnetic. I ended up just permanently borrowing our kitchen bowl from 10-15 years ago. I replaced it with one of the magnetic bowls I found in the store. It's a shame that a stainless steel stamp doesn't really mean much anymore.

There are many varieties of stainless steel. Some are always magnetic. Most stainless steel, even the 300 types, becomes magnetic when it is worked, as sheet stainless is during the bowl making process. They were probably all some variety of stainless.

Dave

 

[BrewCity]

Palladium, thank you again for the clarification on Voltage vs. Amperage for silver crystal formation. Everything is progressing quite well, I believe. My now warm (but not hot) silver cell is continuing to hold steady at 5A and 2.4V. The crystals are forming at a pretty good pace and continue to appear very white/brilliant silver.

UPDATE (7 hours): My cell is still operating at 5A, but the voltage has fallen to 1V. The rate of silver growth is still excellent. I haven't setup lights in the shed (or perhaps lab now) yet, so a picture will have to wait until the morning.

UPDATE (17 hours): My voltage dropped to 0.7V while maintaining 5A. I turned off the power supply, opened up the cell and found a crystal had risen from the bottom of the bowl and into the anode basket. It's unclear if it was fully contacting the anode bag. I knocked down the tall crystal(s) at the bottom of the bowl and the anode basket. Everything was closed back up and power restored. My cell is back to 2.4V at 5A. I will be working on adding a plastic ring to raise the anode bag higher as the distance to the bottom is closer than the sides of the bowl. Crystal growth clearly slowed overall, but they are still clean and the electrolyte is beginning to show signs of copper presence.

UPDATE (22 Hours): Voltage dropped to 1.7V at 5A. Inspection after powering down revealed a new, tall silver crystal which had formed below my anode basket. I again knocked it down with my glass rod. I made and added a plastic ring to raise my anode basket by ~0.5 inches, increasing the short distance to the bottom of my bowl. This process also effectively reducing my (exposed) anode size. I added a small amount of water (my silver concentration was greater than necessary anyhow) to raise the electrolyte level back to the starting level. This was the amount lost by reducing the displacement of the now shallower anode. After reassembling my cell, the voltage has now been increased to 3.0V at 5A.

UPDATE (26 Hours): Voltage dropped to 2.8V at 5A. More uniform growth noticeable but a few tall crystals were knocked down preemptively. Post-tree-felling, after turning the cell back on, the voltage popped up to 3V, but fell within 10 minutes was back to 2.8V. The crystals all over the bowl are forming faster than I had anticipated, which will require more frequent monitoring than I realized (minimum 8-10 hour inspection intervals, but more if possible).

UPDATE (41 Hours): Voltage dropped to 2.5V overnight. Crystals grew up into and formed within the anode basket. Powered down the cell and knocked down the tall crystals as well as intermediate crystals from the bottom of the bowl (probably still the closest point to the anode). All knock-downs were moved to the "corner" of the bowl, or rather the furthest point from the anode. This buildup of materials should make a better-shaped hemisphere, allowing for more uniform crystal growth. Reassembled and powered up the cell. The voltage is now 3.5V @ 5A.

 

[goldsilverpro]

I could use a bit of assistance with my first silver cell.

I've recovered silver from approximately 1855g of Sterling (a few small .8 pieces in the lot). Cementation and silver shot creation appears to be right on schedule. I created quite a bit of electrolyte and made a silver cell as seen in kadriver's YouTube videos (outstanding work, Sir). I'm still working to perfect my bar pouring skills, so for now I'm just using a silver round as my anode shoved into the cemented silver shot (anode basket). My stainless steel bowl holds 2.5L and currently has a silver density of 166 g/L.

The problem is my power supply is running at 3A at about only 2V. If I increase the current, I can reach 3V, but I'm afraid the current would be unexceptably high (and create impure silver perhaps). I understand it should be only about 1A @ 3V. I tried increasing the electrolyte silver density 150g/L to 166 g/L, but it didn't appear to have much effect. Can anyone point me in the right direction to get my silver cell on track?

I appreciate any guidance you all can offer me.

I ran my large 30+ gal silver cells at about 240A or, 8A/gal, with no severe overheating. In sunny L.A., I don't think the solution ever got over 110F-115F, which is OK. Your cell is .66 gal and I think you could run 5 or, maybe, 6A without overheating. The voltage ran between 3 and 4 volts.

HOWEVER:
The amps required are also related mainly to the anode current density (CD). This is the number of amps per square (inch; foot; cm; dm; m; etc.) of electrode surface area. Per square foot is the handiest for me. In a real production sized silver cell the anode and the effective cathode areas are about the same and, in every book I've read, the anode CD should be somewhere between 25 to 50A/ft2 (for a Thum cell, at least). In my cell, at 240A, and 6ft2 of anode bars, I ran about 40A/ft2. The effective cathode CD was in the same ball park.

At the cathode, you are mainly interested in the characteristics of the crystal deposited. The consensus in the literature is that the crystal should be short and dense, mainly for rinsing purposes and being able to pack more crystal in a crucible.

At the anode, you want to dissolve the bars efficiently. At 100% anode efficiency and 1 amp, you would dissolve 4.025g of pure silver in 1 hour. Don't ever expect 100% efficiency.

The silver cell will work (dissolve anodes and plate out crystal) under almost any conditions: hi/lo Ag, hi/lo Cu, hi/lo A, hi/lo V, hi/lo temperature, etc. However, if you want to dissolve the anodes efficiently and get the most desirable crystal, which is pure, you must operate within the proven ranges. You usually have a little slack, though.

You need to estimate the surface area of the bottom of the silver in the basket. For each square inch, you should be in the range of .17 to .35 amps. At that amperage you will pull 3-4V at an anode/cathode distance of 4.5". If the anode/cathode distance is less, the voltage will be less for the same amperage. The amps are the important thing!

 

[Sputins]

Dear GRF,

I’ve greatly enjoyed learning about refining Au and Ag from the advice and information provided on this forum. Professionals are found here indeed.
I’ve been successful at creating fairly clean sliver cement, melting it and forming into nice shiny Ag metal shot. I will soon have enough Ag shot to consider having a go at using a silver electrolytic cell. I have built one very similar to the one kadriver (and others) have built and shown. (Nice work btw). However I may have a go with a beaker with a smaller volume to first to test out my anode basket filter material.

So my question is: What are suitable filter materials for this basket. I am having problems finding some Dacron type material as kadriver used. What else would work? (Obviously resistant to HNO3).

I have found some pillow protector material made of Polypropylene fabric. Sound okay?

Any other ideas for suitable filter material?

I’m looking forward to creating my own lovely looking pure silver crystals.

Sputins.

 

[Lou]

Just get unbleached fine muslin cloth

 

[Research135]

Vacuum cleaner bags are cheap.

BTW and probably not so off-topic: An state-of-the-art thinking and process for all precious metals seems to be converging in: Do all the valuable metals within 24 hours via chemical methods, and process the wastes (copper, etc) electrolytically over days or whatever.

In other words: Silver and gold cells are relics. Old technology. Like black and white TVs. Don't waste your time.

 

[Palladium]

Silver and gold cells are still very much alive in the precious metals industry. They are nowhere near relics. That's like saying the internal combustion engine is a relic because of electric cars.

 

[Sputins]

Thanks for the replies. I can try the muslin cloth and the polypropylene material while I continue to look for a suitable vacuum cleaner bag. (At local stores they're all paper, or no longer hold much stock because of bag-less vacs).

I don’t quite understand the Au / Ag cells are relic old technology comment, without saying why and what replaces it. For me the silver cell is a do-able now process. As you might gather I’m a new comer to refining processes (and to the GR Forum), although I do have over 20 years of experience working in an analytical minerals laboratory.

Picture below shows some feed stock (from cemented silver) for the cell and to prove I’ve actually done something practical. The long slender bar is 1 troy Oz.