Silver Cement directly into silver cell?

[CAustin]

Can I put my dried cemented silver (off copper in nitric) into the basket of my cell? Or is it necessary to pour into flakes/shot first?

Didn't know if it was just a concern of it passing through filter or if there was a slight chemical/property adjustment that occurs to cement silver once heated. I don't think there is but would rather check with the experienced guys before.

Thanks in advance!



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[CAustin]

Didn't have an answer so I went ahead and tried it and figured I'd share the info for others. It works, but not nearly as well as when poured into shot. The fine cement particles pull up the electrolyte solution so the anode sinks slowly like quick sand. Thus, it is eating the anode bar(s) very quickly [had to use 2 small ones now already]. I poured the anode bars from the cement so as to not eat up my other silver. Silver is crystalizing just fine - as normal - on the cathode (SS bowl in my case). Sludge mixes with the cemented silver which is also a drawback.

Used a double lined dacron filter for the basket - no leakage at all of the fine cemented particles, which was one of my original concerns.

My electrolyte had a bit more copper in it than usual from a not-so-clean rinse of the cemented silver.

After running for a couple days I've decided it's best to pour it into shot and use a clean filter basket and keep it running for a direct comparison.

Couple pics attached.

Current had to be much higher, crystalizing slower than I would have expected for the amount of electricity being pumped into it.

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[FrugalRefiner]

After running for a couple days I've decided it's best to pour it into shot and use a clean filter basket and keep it running for a direct comparison.

I didn't respond to your original post since I've never tried using cement directly, so I'd be guessing. I questioned whether the cemented metal would provide a sufficient electrical contact.

If you're melting the cement, why not pour to an anode instead of shot? Again with shot, you depend on contact from piece to piece for electrical conduction. With a solid anode the electrical contact issue is minimized.

Dave

 

[nickvc]

I’m 100% with Dave on this bars are much easier to work with.

 

[kurtak]

What Dave & Nick said

Kurt

 

[CAustin]

Thanks guys! Will follow that advice!

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[CAustin]

After running for a couple days I've decided it's best to pour it into shot and use a clean filter basket and keep it running for a direct comparison.

I didn't respond to your original post since I've never tried using cement directly, so I'd be guessing. I questioned whether the cemented metal would provide a sufficient electrical contact.

If you're melting the cement, why not pour to an anode instead of shot? Again with shot, you depend on contact from piece to piece for electrical conduction. With a solid anode the electrical contact issue is minimized.

Dave

Dave -

Is there any benefit to a nitric refining of silver prior to the silver cell? Or is it more efficient (and with less waste) to melt sterling directly into anode bars and process in the cell?

My current challenge is now with volume. My jeweler partner has given me 10x the amount of metal to refine, which I'm learning how to scale into but it is a big leap. The desired outcome is the same as before - 999 fine bars.

I was thinking to build a new higher capacity cell and pour ~10oz sterling anodes. Might this require 2 runs through the cell? I anticipate more sludge/slime so redesigning my basket as well.

Or is this a fools errand and I should spend my time focusing on scaling the nitric process along side the electrolytic refining?

I appreciate your insights. I think I saw a post a while back saying you go directly to the cell with sterling so thought you'd be the right guy to ask.

- Connor

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[FrugalRefiner]

I do run sterling directly in the cell. There are advantage each way.

The purer the anode, the longer you can run your cell before having to replace your electrolyte. But dissolving and cementing requires more nitric and copper and creates more waste.

Running sterling directly in the cell requires less nitric and copper and creates less waste, but you will need to replace the electrolyte more frequently.

Others may disagree. It's just my personal preference.

Dave

 

[CAustin]

I do run sterling directly in the cell. There are advantage each way.

The purer the anode, the longer you can run your cell before having to replace your electrolyte. But dissolving and cementing requires more nitric and copper and creates more waste.

Running sterling directly in the cell requires less nitric and copper and creates less waste, but you will need to replace the electrolyte more frequently.

Others may disagree. It's just my personal preference.

Dave

Thanks for the insights Dave. I'll give it a shot. Did 2kg of metal last month - so much rinsing of the cement - easier to wash crystals haha.

Will keep you updated.

Cheers

- Connor

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[g_axelsson]

I agree with Dave, it will foul the electrolyte faster but create less waste.

If you run the cell until the quality is too low you can always rerun the last batch of crystals. Running almost pure silver only takes some time and power, it doesn't consume any extra chemicals or generate any extra waste.

Göran

 

[CAustin]

I agree with Dave, it will foul the electrolyte faster but create less waste.

If you run the cell until the quality is too low you can always rerun the last batch of crystals. Running almost pure silver only takes some time and power, it doesn't consume any extra chemicals or generate any extra waste.

Göran

Thanks Göran - gonna give it a shot. Sounds better in theory and also with both your practice. I'd rather deal with replenishing electrolyte than rinse cement rinse cement repeat repeat repeat.

Either way - growing and learning and enjoying every minute.

Cheers

- Connor

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[nickvc]

You can run sterling in a cell I did nearly 100 kilos with two or three electrolyte changes but to do that you need to add more nitric into the cell to dissolve some of the refined silver to keep the base metal content in the electrolyte down and the silver content up to avoid codeposition, I did it by eye adding more nitric if the color of the electrolyte started to change noticeably, takes a little practice but very possible.

 

[CAustin]

You can run sterling in a cell I did nearly 100 kilos with two or three electrolyte changes but to do that you need to add more nitric into the cell to dissolve some of the refined silver to keep the base metal content in the electrolyte down and the silver content up to avoid codeposition, I did it by eye adding more nitric if the color of the electrolyte started to change noticeably, takes a little practice but very possible.

Haven't heard that tip before but it makes sense. I have two cells going and will try this method in one of them vs the "swap when spent" approach.

100 kilos - nice !! I'm up to 3.5kg this cycle and hope to catch up to you one day. Each time I go up in lot size it comes with a whole new set of learnings.

Are those self-developed cells or purchased manufacturing equipment at that scale? Impressive either way.

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[nickvc]

The cell was made from a stainless pot that if I remember correctly was 10 litres and I used a plastic colander suspended into the pot with a filter cloth liner, very simple and easy to use.

 

[CAustin]

The cell was made from a stainless pot that if I remember correctly was 10 litres and I used a plastic colander suspended into the pot with a filter cloth liner, very simple and easy to use.

Wow - how didn't I think of the colander- genius !

Got my new larger cell up and running this morning (and over the last few days) now processing ~115 ozt of Sterling.

I'll post a larger update in this thread shortly with pictures for everyone that helped to see and critique/advise. Its not my first time with a silver cell but first time at (what I at least consider) a non-hobby volume.

Thanks for the tips.

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[CAustin]

Here's an update - using a new (larger) cell.

14qt stainless steel pot. There are some rivets for the handle 1.5-2 inches down, so the final filled volume is closer to 11-12qts.

I have 75ozt of Sterling silverware poured into bars, with the flat sides touching for (hopefully) decent contact. There are 2 bars on the bottom of the basket for extra surface area, and the third with the small tongue resting on top, with the anode clip.

The basket is just a Tupperware with some holes drilled into the bottom, and dacron filter bag - double lined. The electrolyte fills the bottom 1/4 to 1/2 inch of the basket.

The anode bars are about 4-5 inches from the sides of the pot, and probably closer to 6 or 7 from the bottom. Thus, I'm noticing the sides plating with crystals quicker, but still some growth on the bottom.

The electrolyte was made by taking 1/3 of the total sterling supply I had for this run and dissolving it in nitric - about 1200g. Then cemented with copper. I rinsed the cement with nearly 3 gallons of boiling distilled water but it still had a slight blue green tint. I got the rinse quite clear and light, and figured a little extra copper would be okay for the electrolyte as I had seen references to 30g/l copper addition on the forum here.

Well, it ended up being more copper nitrate solution left than I had hoped, and the solution was quite dark blue once redisolved in nitric. I also work out of my garage - fume hood and safety measures in place - and had to open it for a refrigerator delivery (for the inside of the house). This made the solution darker, as I believe the strong Florida UV rays converted some of the silver nitrate. I was worried at this point my electrolyte wouldn't work, but decided to give it a shot.

I set up the cell this morning, turned it on, and seem to have a good current. 3-4 volts hovering at .85-1.4 amps. Happy with that at least and the initial few hours have been promising.

Ultimately I only have about 95g/l of silver in the electrolyte, so I imagine I will be replenishing it quickly here and am keeping a keen eye on it. That was another mistake as I was aiming for 100g+/l but was trying to avoid excess nitric and left some of the cement undissolved while preparing it.

This is my first time with a batch this large going into a cell of this size. I have my learnings in my notebook already, and will surely have more to come. But I'm posting just to share and hopefully it'll elicit further tips as well.

Pics are of the cell wall after 4 hours, cell itself, anode bars in basket, (too dark) blue electrolyte, cast sterling anode bars, sterling flatware itself, and a bonus pic of some finished bars from my last round - tested 999 fine at jewelry store. Will keep practicing my pouring ability. Plus 8.5g of gold from some gold filled stuff I had - first ever gold processing for me last month.

Thanks!

- Connor

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[CAustin]

Another update with pics.

All going smooth in both cells. Harvested some crystals today since I needed to switch out the electrolyte. Poured a couple tests bars and took to the jeweler to confirm 3 nines fine.

Siphoned off electrolyte, dropped the silver with copper, filtering now and re-dissolving to create a new batch of electrolyte.

So, can confirm now through experience that sterling right into the cell works just fine - saves a lot of work and nitric, like the guys above said when offering their advice.

10 qts is too big of a container for me though. Will stick with my 5qt bowls moving forward. Uneven crystal growth on the big pot and took a while to get it cruising.

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[g_axelsson]

Looks great!

When the electrolyte turns green when dissolving the cemented silver you have accumulated some PGM:s with the silver. At that time you could melt the cemented silver and run it through the cell, catching some of the PGM:s in the anode mud.
If the PGM:s are mainly palladium you could use DMG to remove palladium from the electrolyte, filter and return it to the cell. The last part can be a bit tricky. If you get too much DMG into the electrolyte then it might precipitate palladium outside of the filter bag and mix with your crystals. Just as running the cell takes some practice to get a smooth operation, it takes some training.

But at the moment I don't see any signs of PGM:s in your electrolyte.

Thanks for sharing!

Göran