Stainless Steel Silver Cell

[mikeinkaty]

Dawg,

I would suggest that you have the engineer install several (4 equidistant) lugs around the periphery of the tank.

Then, using equal length leads, you can attach the negative from your power supply to these four points

If you have just one lug, then the electrical flow will cause the silver to form more densely at that one point in the cell.

By having four lugs and using equal length leads to each lug, you will distribute the electrical flow evenly and the silver crystal formation will be more uniform.

Now I see what you were talking about in your PM.

Thank you,

kadriver

Rather than drill holes in the bowl why not just secure a #10 or #12 copper wire around the outside of the bowl. Get a SS or plain steel hose clamp (the kind with the screw adjustment). Cut it a couple of inches on either side of the adjustment screw. Drill a hole in each end to secure the ends of the copper wire. Then put it around the bowl and snug it up as tight as you can.

For example: http://www.staples.com/office/suppl...angid=-1&cid=PS:GooglePLAs:859039&KPID=859039

Mike

 

[mikeinkaty]

 

[rybak97]

Ive been running my SS cell for about 3 hours at 3.2V (4.0 amps) and it feels like its heating up. How warm can the solution get before I start to have problems?

I didnt have this problem when I was running the cell in a plastic container with a SS cathode. I think because the lid is styrofoam its insulating the cell. Have you had this issue?

 

[element47.5]

I like that clamp deal, Mike. Clever & cheap!

 

[mikeinkaty]

Ive been running my SS cell for about 3 hours at 3.2V (4.0 amps) and it feels like its heating up. How warm can the solution get before I start to have problems?

I didnt have this problem when I was running the cell in a plastic container with a SS cathode. I think because the lid is styrofoam its insulating the cell. Have you had this issue?

Did you have the same amount of electrolyte in the plastic container and did you actually measure the temp of the solution? The SS probably feels warm because it is conducting more heat out of the solution which plastic would not do. The electrolyte in my rust removal cells would get close to boiling. I was running them at 20 amps for the bigger pieces.

Mike

 

[rybak97]

Ive been running my SS cell for about 3 hours at 3.2V (4.0 amps) and it feels like its heating up. How warm can the solution get before I start to have problems?

I didnt have this problem when I was running the cell in a plastic container with a SS cathode. I think because the lid is styrofoam its insulating the cell. Have you had this issue?

Did you have the same amount of electrolyte in the plastic container and did you actually measure the temp of the solution? The SS probably feels warm because it is conducting more heat out of the solution which plastic would not do. The electrolyte in my rust removal cells would get close to boiling. I was running them at 20 amps for the bigger pieces.

Mike

Exact same amount of electrolyte. I think you’re right about the conductivity. Add to that the 1in Styrofoam lid and it makes for some warm solution. I ended today and will be posting some pics on my Thum cell thread. It worked out pretty well!

 

[lazersteve]

Is anyone out there paying a higher rate for 4N silver verses 3N silver? I love to run my cell just as much as the next guy, but it's not really necessary unless your buyer requires 4N+ purity, and the buyer is willing to pay you for the increased purity. My silver buyer pays the same percent of spot for minted 4N silver bars and coins as he does for 99%+ silver that has not been through the cell.

I would love to hear what everyone else thinks about this point.

Steve

 

[its-all-a-lie]

Is anyone out there paying a higher rate for 4N silver verses 3N silver? I love to run my cell just as much as the next guy, but it's not really necessary unless your buyer requires 4N+ purity, and the buyer is willing to pay you for the increased purity. My silver buyer pays the same percent of spot for minted 4N silver bars and coins as he does for 99%+ silver that has not been through the cell.

I would love to hear what everyone else thinks about this point.

Steve

I prefer to run my silver through the cell just for my peace of mind, to simply know i have ATLEAST .999 purity. I do not sell any of my silver except on rare occasion and have not had any luck refining to a guaranteed 3N with any other method. The reason i say this is because i did a trade with scrapman for some of his rounds several months ago, almost a year ago and the assay on refined/recovered silver that was only cemented with copper and washed several times with ammonia and hot water assayed as follows:
Beginning Weight(with bag): 34.91oz

After Weight Melt: 33.54oz

AG: 96.34%
NI: 1.75%
CU: 1.91%
This^ material was all flatware that had been dissolved in nitric and cemented with copper, washed in alternating baths of hot ammonia and hot water and filter through the buchner. There appeared to be no traces of copper in the cemented silver after 4 washes as the rinses ran clear. I prefer to run through the cell so i know for sure my finished product is pure. As for selling at a higher premium, i cant get a better price from my buyer for 4N vs. 3N so when i have to sell i only sell sterling jewelry items and hold on the flatware/holloware for refining. My buyer pays me 86% spot for sterling items on the scale and 100% spot for silver eagles but i will be damned if i will sell them to him!

 

[Anonymous]

Since I've been refining silver already and I've been reading this thread trying to keep up with it, I'm going to build me a stainless steel cell so I can learn about really getting the purity as mentioned through this method. My understanding has increased a bit, and I'm sure once I reread this thread from the beginning, it'll make more sense to me.

I like the setups too. I just never understood how to make it work properly to refine pure silver.

Kevin

 

[Palladium]

I've thought about the same question myself. For me i guess it's about producing the highest quality of metals possible. Sure my customer doesn't pay that much of a higher premium, but i know in my mind that know matter what my product tests it will at least meet their minimum requirements no matter what. I do my gold the same way to. I don't stop at .995, i try to blow it out the water. I now do a min of 3 drops on my gold and have learned that's it's not that hard or costly to go that extra mile. I want my customers to go WOW! I dare every customer i have to pull assay's on my materials. It's the quality, product, craftsmanship, and reputation for such metals that sells and sells well. Johnson Matthey and Argor-Heraeus sell their image for quality as much as they do their products.

 

[nickvc]

For me the reason to use the cell is to remove the other values before selling onwards and as most buyers don't care about the actual purity when it comes to the percentage paid commercially it doesn't make much sense to run it through the cell unless you have other values to collect.

 

[lazersteve]

Silver cemented on copper is never up to my standards in many respects, regardless of how much washing and rinsing is involved. Silver produced via sugar and lye is very pure, over 3N in most cases with careful attention to washing and the proper handling of the silver nitrate solution prior to precipitation of the chloride.

I would strongly advise everyone to keep ammonium hydroxide out of your refining processes if at all possible. It can easily form very explosive compounds and makes disposing of your wastes a real hassle.

My silver chloride conversions have never assayed with any gold, palladium, or platinum present. The reason for this is my attention to proper filtration prior to precipitation of the chloride and attention to testing my rinse solutions. Filter your nitrate 100% transparent and free of particulate, precipitate with HCl (muriatic acid), filter, press, wash with hot water, filter, press, test rinse water for lead, copper, nickel, and precious metals (if present more hot water rinses). The silver chloride is now very pure and conversion should go smoothly without any metal contamination. Precious metals are either caught as solids in the initial filtration or dissolved by the AR formed when HCl is added to the nitrate solution, so they never make it into the silver. Base metal nitrates are removed by hot water rinses, filtering, and pressing. Testing of the filter water ensures no soluble base metals are present, if they are present more washes are necessary before converting or melting.

I have updated the Guided Tour link to include acquaintance tests for identifying base metals in solution.

Steve

 

[lazersteve]

I've thought about the same question myself. For me i guess it's about producing the highest quality of metals possible. Sure my customer doesn't pay that much of a higher premium, but i know in my mind that know matter what my product tests it will at least meet their minimum requirements no matter what. I do my gold the same way to. I don't stop at .995, i try to blow it out the water. I now do a min of 3 drops on my gold and have learned that's it's not that hard or costly to go that extra mile. I want my customers to go WOW! I dare every customer i have to pull assay's on my materials. It's the quality, product, craftsmanship, and reputation for such metals that sells and sells well. Johnson Matthey and Argor-Heraeus sell their image for quality as much as they do their products.

Do you run all of your gold through an electrolytic cell? If not, do you not have peace of mind with the purity of your gold? Peace of mind for me does not come from using a particular technique for refining my precious metals, it comes from performing the techniques that I use to the best of my ability. If you can achieve market quality gold using wet chemistry alone, what makes you think market quality silver cannot be attained using wet chemistry also?

It's not the process you use, it's your attention to detail with the process you choose. Refining metals to high purity is more about discipline. Just because one uses a silver cell to refine their silver, does not guarantee high purity silver. Careless use of the cell or poor control of the cell operating parameters, can lead to silver that is no more pure than the starting silver. I find the silver cell to be a useful tool when a customer sends me bars of cast cemented silver. If I receive dirty silver bars for refining, I use my silver cell. If I get silver scrap in a form used by consumers, I process with my own methods that give me a purity of equal or greater purity than the cell will produce. I have 100% confidence of my final product, as my methods are tried and true when properly performed.

Steve

 

[kadriver]

Steve, I have produced cement silver (cemented on copper) that appears as pure as silver that has been through my silver cell.

To get this level of purity out of cement silver, I use coils of clean copper wire. As the silver cements I knock it off and then pull the coil out of the silver nitrate before all the silver has cemented out, filter, rinse, dry and melt. Then add a fresh coil of copper to get the rest of the silver and other PMs if present.

I know that other metals will still have a chance to contaminate the cemented silver, but it is usually very pure and well suited for my silver cell. The cement silver made in the way described above is so devoid of any copper that the electrolyte in my silver cell turns a pale yellow rather than blue or green.

But recently, I have just cemented ALL the metals out after dissolving the sterling 925 in dilute nitric.

This last batch that I have been working on has produced some very black powder toward the end of the cementation. It actually turns the cement silver powder a very dark grey color and it is very difficult to melt. I hope this is not just copper, but maybe some PGMs.

I think that running all the silver through the cell is still the best way to get the bonus metals that sterling and 925 silver are known to carry - especially the 19th century silver items.

I have been saving all my silver cell slimes in a 2 liter beaker. There is about 1/2 inch of undissolved material in the bottom of that beaker. It is probably mostly dirt and other waste, but a stannous chloride test on some of it dissolved in dilute nitric indicates at least some palladium is present.

I am saving the slimes until I find a good solid method to recover all the precious metals that the slimes might contain. Plus I will have a fairly good sized batch to work with.

I once dissolved a large 700 gram heavy silver mug from the 1800s. It was not marked and the silver was only about 80%, but the material left in the filter after dissolving yielded about 1.5 grams of gold from just that piece! I know this is probably a rare occurrence, but it does reveal that silver (especially older pieces) carry other metals of value.

I am selling my 5 troy ounce silver bars from my silver cell for about 15% to 20% over spot, just sold 7 of them yesterday on eBay, open auction starting bid at $0.99 with no reserve. One of them went for $148. With silver hovering around $23, that is $33 over spot or nearly 30% over spot!

I usually only get about 10% over spot. To me this means that silver is unusually low or over sold right now. I always pick the best looking 5 ounce bar and save it for myself out of each batch of silver bars that I sell to be stashed in a secure location (in the ground).

To me it is important that these bars are as pure as I can possibly get them for the customers who buy my silver bars.

The silver from my silver cells always assay at 3N plus, probably closer to 4Ns.

kadriver

 

[lazersteve]

Kevin,

The gold in the 1800's sterling is easily recovered in the filtration stage of dissolving the sterling with 50/50 nitric acid. The hardest metals to get out when using dilute nitric on sterling are the PGMs. Palladium is easily dealt with by using DMG to scavenge the Pd from the nitrate solution. Platinum is not so easy to remove from silver nitrate, but one can easily remove the silver as the chloride leaving the AR with Pt in it behind. Then the Pt can be recovered normally. A plus to working with silver nitrate solution containing PGMs is that the PGMs are easily tested for with DMG and stannous after the silver is removed. It's pretty rare to find Pt alloyed in silver, but it's not unheard of. Pd on the other hand is pretty common in silver products.

My biggest hang up with cemented silver is that you have to increase the copper concentration so high to get all of the silver out. The highly concentrated copper solution require copious amounts of rinsing to get it all out. Then you have to deal with all that copper nitrate solution. When making silver chloride using HCl, you get all of your nitric acid back (minus the little bit that turns to NOx) and you can use the liquid all over again for AR. If you have some silver nitrate crystals on hand and are meticulous with your HCl additions, you can even use the left over nitric acid on silver again. If you are heavy handed with the HCl, add a little silver nitrate to scavenge the left over chloride, filter and your solution is ready for more silver. You can cut your nitric consumption for silver in 1/2 or less. Your new spectrum analyzers device would come in real handy checking for free chlorine.

I still run my silver cell, but only when customers send me impure silver bars to refine. There is no difference in the final assay between properly refined silver from the cell and properly refined silver chloride. For me the silver chloride route is faster than the cell and I get the Gold and Rhodium out on the front end instead of the back end of the reaction. DMG makes short work of any Pd that tags along in the nitric acid, and Pt is seldom seen. Finally, I only have to melt the silver once when using the silver chloride route. With the cell, the cemented silver has to be melted before it goes into the cell and when it comes out.

Steve

 

[kadriver]

All good stuff Steve, thanks for sharing those insights.

I have used the silver chloride route to get fine silver.

I have heard it mentioned, but I have never thought of saving the nitric for dissolving more silver!

I once converted about 2 liters of silver chloride to pure silver. After converting to silver oxide with NaOH, I added regular cane sugar, about 2 cups.

The reaction happened so fast that the silver came shooting out over the top of the container like a volcano.

After that I made sure to add the sugar very slowly.

Then, I wanted to show my wife the volcanic reaction (from a safe distance), so I put the bucket in a large catch basin and added the 2 cups of sugar all at once to demonstrate the dramatic effect of the silver erupting.

Well, it just set there gurgling and it never did react the way it had before.

Refining is baffeling at times because some reactions happen so differently even though the same conditions are strenuously duplicated.

The pure silver from the silver chloride reactions was very pure and very beautiful.

I have a big lot that I am working with currently, and I may study your words above and get the PGMs as described so I can get this batch of silver refined.

The 3.5 liter silver cell is taking forever (it seems) to process the kilos of sterling that I have.

Thank you, kadriver (Kevin)

 

[solar_plasma]

The gold in the 1800's sterling is easily recovered in the filtration stage of dissolving the sterling with 50/50 nitric acid. The hardest metals to get out when using dilute nitric on sterling are the PGMs.

Wow, that is new for me, though I wondered earlier, if there might be pm's in 19th century's copper. Can you make a guess based on your experiences, how much gold or pgm's there could be in 1800's sterling? Are 2g of gold on 750g silver typical? I have 80 g (maybe 120g) 80% silver from that time. So, this would be quite interesting for me, when I once will refine it, though I will wait till I have more of it.

 

[samuel-a]

Steve

We buy 4N silver at -2% or -3% and charge the client for the assay. Good for him if he has over few Kg.
Lower than 4N we will charge refining + assay and then pay anywhere from 80% to 96% of spot (depening on actual silver conent in the melt)

 

[lazersteve]

Kevin,

I always dissolve my table sugar in warm water first before adding it to the basic silver oxide solution. I have found that the dry sugar tends to clump into gooey pockets when added if the sugar is not dissolved first. These gooey clusters tend to slow the silver conversion. When you dissolve your sugar shoot for a saturated solution. I always leave a little undissolved sugar in the bottom of my sugar water after it is vigorously stirred, to ensure saturation.

The conversion stage of the reaction is the easy part, the more difficult part is the filtration and hot water washing prior to conversion. These stages are where the purity is most affected and attention to detail is critical. I find squeezing the silver filter ball helps the process of washing complete. A filter press would be great for this process. Proper testing of the wash solution is also a key point in high purity. I have recently added a link to the Guided Tour on identifying base metals in solution. There is a ton of information in the one new link, but it's worth reading and even printing for reference some of the tests.

I'm glad I can help you Kevin, you have been a great asset to this forum.

Steve

 

[piccolim]

Here it is

http://www.ebay.com/itm/30V-10A-10AMP-3010D-Pro-Digital-DC-Power-Supply-Precision-Variable-Adjustable-/330873545740?pt=LH_DefaultDomain_0&hash=item4d0999a40c

Are you better off with a 30V-10A unit or will a 30V-5A do the same for the purposes of the silver cell? Or if I also wanted to use it to deplate gold pins for ex. should one stick to the 10A model.
thanks
mike