# 3rd generation cell



## mikeinkaty (Apr 10, 2013)

This one is using a 304 SS bucket, 7.5" diam. and 8" tall with straight sides. I'm using 3.5 L of electrolyte (6" deep) that had 15 ozt of 999+ silver put in solution. When disolving the silver I threw in 5 grams of copper. I have a plastic circle blocking off the bottom of the pot. 

I put two 6 ozt 990+ anode bars in for a total of 16 sq" of surface area. It runs 1V=5.5A, 1.5V=7.5A, and 2V=10A. I'm running it at 1V now. Next anodes I'll kick it up to 1.5V. I did put about 2 grams of Tartaric acid in the solution (beer making store 1 block away). I'm thinking 17 hrs for this 1st 12 ounces, or about 0.7 ozt per hr running at 5.5 amps. If I can run it at 10 amps and not get to hot and still get good crystals I should be able to process 12 ozs in about 9.3 hrs. I am not getting edge effect crystal growth in this one!

I thought my Ph test strips would be here today but they didn't show.

Mike


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## mikeinkaty (Apr 16, 2013)

Got two batches processed. Each batch was two 6.5 ozt bars.
Observations -
After the first batch I poured off the AgNO3 and carefull collected all the crystals. The wt of the silver plus the little anode stubs was 15 grams more than the initial weight of the anodes. The calculated amount of Ag depletion from the solution was about 23 grams assuming 995 purity for my anode bars. So, that looks good. The 1st batch was run at 1V and 5.5 amps for the first 6 hours then the current started dropping so I changed it to 1.5V and 5 amps for most of the remainder of the run. I cut it down to 3A the last 2 hrs. 

But, I got mostly thick silver plate instead of crystals. I was like pealing 3"x3" pieces off the walls of the SS bucket. There were heavy and covered with small crystals. They were very clean and the bars I poured from it behaved like and appeared to be 9999. The plating was hard to get off. Took me 15 minutes to get it out. Note that in the previous post that I had added 5 grams of CuNO3 to the solution. When I restarted the cell for the 2nd run I added 0.5 ozt more copper (CuNO3). Note in the first post that I had also added 2 grams of Tartaric Acid. 

The 2nd run was about the same as the first but the plating came off easier and there was less plating and more crystals. I ran most of the 2nd run at 6 amps then lowered it to 4 when the anode looked 2/3rds gone or so. The solution had no noticable difference in temp than the first. (my temp meter was not working)

The plating might be due to the SS bucket I choose or to the Tartaric Acid I added. The bucket is brushed SS on the inside and not mirror finish. Or, that might explain the difficulty of getting the silver plating to break loose. I don't mind working with the plating because it easily broke up into small pieces plus the density (wt per unit volume) was greater.

I'm out of sterling now but I have another 1oz of Cu ready to add to the solution when I do start up again. 

Mike


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## rybak97 (Apr 16, 2013)

Hi Mike,

Do you have a picture of the new cell you could share?


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## mikeinkaty (Apr 16, 2013)

rybak97 said:


> Hi Mike,
> 
> Do you have a picture of the new cell you could share?



It's just a SS stock pot with a 7-3/8" id and 7" tall and vertical sides. I put 5" of electrolyte in it. Have a #12 stranded copper wire around the outside at the top similar to an earlier pic I posted. The lid is a piece of Lucite plastic with 1/8" holes in the center for hanging the anodes. The lid really cut down on evaportion. My power source is a Variac that goes up to 20 amps and 120 volts. I need to get a step down transformer so I can have more variability with the Variac. Might help too if I put a big electrolytic capacitor across the output to filter out some of the AC ripple. Haven't noticed anything though in previous cells that would suggest one was needed. It will be several weeks before I get this latest one back in operation. Summer is here - other things are pressing.
Mike


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## FrugalRefiner (Apr 16, 2013)

Mike,

Are you saying you are using AC to power your cell? :shock: 

Dave


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## mikeinkaty (Apr 16, 2013)

FrugalRefiner said:


> Mike,
> 
> Are you saying you are using AC to power your cell? :shock:
> 
> Dave


No, it's full wave rectified. The bottom half of the sine wave is filpped to the top of the chart! Putting a electrolytic capacitor across the output terminals of the rectifer will make it closer to pure DC current. But, it's still a 'rippled' wave. Good filtering can get to almost a steady DC current. I just bought six 22000 uF 16V Electrolytic Capacitors on eBay. I'll rig up two on each of my Variacs and have 2 for spares. The full wave rippling may incourage plating instead of crystals. Although, I've never had that problem with smaller cathodes. This way I can test that question.
Mike


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## FrugalRefiner (Apr 16, 2013)

Thanks for the clarification Mike. I can rewire a house, but once you start including parts made with the magic smoke inside, I get lost.   

Dave


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## butcher (Apr 16, 2013)

Mike I do not think you would have to be that concerned about a little ripple in your DC from your power supply, in fact it could even be a good thing in some circumstances (like a little chloride passivisation of your anode or a build up of PGM).

In the cell itself the ripple is not going to make that much overall difference in how well the silver plates out, but it could actually be somewhat helpful at the anode to shake loose the passivated material at the anode, at the cathode it could also help somewhat in rejecting plating of the base metal impurity. so personally I believe having just a little ripple would be better than having too smooth of a power supply.



If you still believe you need a truly smooth DC current (I do not believe it all that necessary), then I would look at switching power supply's.


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## mikeinkaty (Apr 26, 2013)

butcher said:


> Mike I do not think you would have to be that concerned about a little ripple in your DC from your power supply, in fact it could even be a good thing in some circumstances (like a little chloride passivisation of your anode or a build up of PGM).
> 
> In the cell itself the ripple is not going to make that much overall difference in how well the silver plates out, but it could actually be somewhat helpful at the anode to shake loose the passivated material at the anode, at the cathode it could also help somewhat in rejecting plating of the base metal impurity. so personally I believe having just a little ripple would be better than having too smooth of a power supply.
> 
> ...


Bucher - No, I don't believe it is necessary. I have been using full wave rectification with no filtering and get good crystals. Just something I want to test. I'm thinking that if anything, that no filtering might encourage smaller crystals. One way to test it would be to just put a bunch of D size batteries in parallel. Mike


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