# Silver Cell?



## toadiesop

Maybe it has been posted elsewhere but a thread here would be good.

Is there a such thing? What it the process? Thrift stores have many plated items (silverware, serving trays, ect.) for really cheap. Mine sells silverware (hundreds of them) for 10 cents each and some large serving trays (some two feet long) for 1 dollar.

What are some processes for getting just the silver off?


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## lazersteve

You would need to setup a large silver stripping cell for the tray. You could reverse the electroplating process to strip the silver. Here's what wiki has on the subject of electroplating:

http://en.wikipedia.org/wiki/Electroplating

If you read thru the article you will see that it states in the Current Densities paragraph that reversing the current will cause the silver to reverse plate. 

I'm sure Chris can provide information an actual setup for this type of activity. 

Steve


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## goldsilverpro

A traditional silver cell is only used to process solid silver that is at least 90% (sterling silver, e.g.) pure to 99.99%. Like aqua regia is for gold, a silver cell is the final purification step for most silver recovery operations, no matter what items are started with.

Most all silver plated materials have copper or copper alloys underneath the silver. I know of no common cell that will selectively remove silver plate from copper based items, except the strong sulfuric cell that you are presently using. However, what do you do next, economically? Silver stripping was included in the original sulfuric patent but, I've never played with it. The patent holder was a plater and stripping faulty plating was the original intention of the patent

I once developed a cell using cyanide plus a large amount of sodium hydroxide that didn't eat the copper and worked quite well but, you had to keep the parts moving in a tumbler. The silver (or, gold) that stripped automatically plated out on the cathode. The coinage metals, gold, silver, and copper, are found together in nature and have many chemical properties in common. All can be dissolved in cyanide, for example. The high sodium hydroxide in my cell slowed greatly the attack on the copper. This system is, obviously, beyond your scope.

In the books, about the only method given is the super nasty, super dangerous hot concentrated sulfuric plus a little nitric - I think they say 5% for the nitric. No electrolytic cell. All you have to do is immerse the parts. For thin plating, heating isn't necessary. Here again, this process doesn't work economically. It's designed to strip faulty plating off so the parts can be replated. 

Most refiners don't want silver plated items. Basically, silver plated copper is considered as contaminated copper. Most silver plated copper only runs 1% silver. Some silverware is higher. Don't buy it unless you pay a lot less than copper price. If you do have a bunch of it, look for a refiner that burns boards, melts all the resulting metals into ingots that run about 65% copper, and then ships the ingots for further refining. He might, just might, pay you a small price over copper market. He always needs cheap copper and can add the stuff to the melt. He often needs extra copper to lower the melting point of hi-temp melting items containing lots of iron and nickel. The big smelter he ships to will pay him for the silver.


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## shadybear

I was wondering this as well about silver plate it is cheap!
I think the last silver plate I bought at an auction I paid 9 dollars
for 7 pounds of forks and spoons. And I have another box of teapots,
creamers,trays etc I picked up for 1 dollar, I also purchased a silverplated award platter for the 
G.V.C. Badminton 1951 Mens Doubles, runner-up that cost me 2 dollars.
I couldnt pass that one up, I probably would have paid 5 dollars for that
platter just so I could say I did.

Anyway here is my thought, What is the hardness of copper and silver
Isn't silver softer? If silver is softer and you placed the plated items in a tumbler with an abrasive that was harder than silver but softer than copper wouldnt it remove the silver


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## AuMINIMayhem

What about dissolving it in Nitric, then precipitating it out with table salt, etc.. (See Lazersteve's tutorial "Seperating gold from silver").. do you really nead to be seperating it from gold or would that method work for the metals that silver is normally plated to (ie: copper, etc)..


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## lazersteve

*NOTE:*
Since my video Harold has pointed out that copper bus bars or a cut ring of copper pipe will drop the silver as cemented silver without producing silver chloride. This method is better because it avoids the production of silver chloride which can be hazardous and difficult to work with. According to GSP (Chris) this is known as the Silver Chloride Aversion (meaning you should avoid making silver chloride unless absolutely necessary).

Steve


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## AuMINIMayhem

yeah, I was wondering about that myself.. Silver Chloride can be pretty nasty if you're not careful with it. Is there any loss in purity from taking silver chloride and reducing/refining it to silver versus the copper method?..


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## austexjwlry

Goldsilverpro

Would increasing the glycerine amount in sulphuric/glycerine recipe increase silver stripping ability of electrolytic cells in general? Offhand is there a better catalyst to use?

Thanks, as always, for your help!

Wayne


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## goldsilverpro

I have never used glycerin in the sulfuric cell. In fact, I've never gotten a good explanation of why it is used. I have also never used the sulfuric cell for stripping silver. The hassle of getting it out of the solution has always outweighed the benefits. The patent was used to reclaim and eventually replate parts that had faulty plating on them. I don't think that the reclaiming of small amounts of $1.29/tr.oz. silver ever entered their minds. 

Trust me, there is no economical way to recover silver from silver plated copper alloys, except for maybe the cyanide/hydroxide electrolytic method that I mentioned earlier. This is a shame since there are zillions of tons of this material out there. It is basically contaminated copper. If anyone ever figures out how to do it, they could become wealthy. Good luck.


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## Noxx

GPS, not 1.29$/T. oz. 

Silver is now at 13$/T. oz. I think.


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## austexjwlry

goldsilverpro

I even bought a air die grinder and large carbide cylinder burs & bud burs etc. Ran with 5hp 30 gallon air compressor, grinding in a small sand blasting cabinet . I tried silverware, platters, cups, vases etc. It was a very loud, labor intensive type of work! It simply wasn't worth doing...!

Thanks again,
Wayne


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## goldsilverpro

Noxx, I was thinking about the price in 1940, when the patent was written. This price made a silver dollar worth a dollar.

Actually, I just looked up the prices and I was wrong. The 1940 average price was about $.35/oz. The $1.29 didn't come into play until about 1963.

Austex, I bet it wasn't worth it. I'm glad it was you doing it and not me. Steel shot peening would work but it might not be worth it either.


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## Noxx

Oh sorry.


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## Harold_V

goldsilverpro said:


> Actually, I just looked up the prices and I was wrong. The 1940 average price was about $.35/oz. The $1.29 didn't come into play until about 1963.



Notwithstanding, your comment was deadly accurate. Silver coinage was struck based on a silver value @ $1.29/ounce. 

It might come as a surprise to those of you that remember the silver dollar that ten dimes weigh the same as a silver dollar, as do four quarters or two halves. 

Harold


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## austexjwlry

Goldsilverpro

I've made a second test cell for silver. I'm going to try Liquid Fire drain opener with 5% nitric, no glycerin. This is a pyrex pan with copper cathode, contact strip and anode.

I bought a crock pot with removable ceramic insert to turn into a heatable cell, will use a copper cathode, contact strip, and anode in this cell also. In Hoke she mentions using heat to expedite dissolution of silver used for inquartation of gold. Do you think the additional heat will adversely affect cathode, etc. in conjunction with electrolytic cell? This little cell will hold 6 cups sulphuric with room below cathode and anodes for settling silver sulphate etc. Might it also be a slight improvement for gold plated electrolytic cell?

She states in using sulphuric for removal of silver when used for inquartation technique that it takes from 2 to 3 ounces of sulphuric for each ounce of metal approximately. With approximately 48 ounces of sulphuric in cell it should hold around 16 ounces of metal. I'm guessing at least a third of that will be base metal, leaving about 10 ounces silver with recovered value of about $13 an ounce, not too bad for about $10 sulphuric and lots of labor to make plated scrap fit into cell. Using your and Catfish's formula for surface area and approximate thickness to estimate amount of silver return, I'd better buy silver plate pretty cheap to make a profit! This is kinda depressing before I even start! I should probably make a large enough cell to strip whole pieces without having to cut anything to fit in cell.

Hoke also mentions the possible use of potassium nitrate with sulphuric. Would the potassium nitrate from farm supply work if liquefied with water then siphoned off sediment and filtered? She doesn't mention a recommended strength or percentage. I suppose I should boil down to remove water so I don't dilute sulphuric too much and will also increase strength. Am guessing I should use about the same 5% as called for using nitric. Have you ever used this material with sulphuric in reverse plating?

Would I do better using an iron or mild steel cathode? I'm going to play around with this but any further advice would be greatly appreciated!

Will precipitate exactly like when using nitric, with table salt. Then wash many times to remove other base metals etc., until clean. Use karo syrup, then add lye or viceversa and wash many times, and melt.

Thanks again for all your help on the forum!

Wayne


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## goldsilverpro

Wayne,

I'm having a little problem following you but, it seems that what you are doing could be very dangerous.

I have never seen the 95H2SO4/5HNO3 combo used electrolytically and see no reason for doing so. This is an immersion method. It works slowly at room temp. You can speed it up with heat but, hot concentrated sulfuric is very dangerous to work with, especially when you've added nitric to it.

There is a very good possibility that the conc. sulfuric will eat the glaze off of the crockpot. If this happens, the ceramic will soak up the sulfuric like a sponge and will break when heated. Talk about dangerous. I've been there and done that.

Getting the silver out of the conc. sulfuric is a big problem. You can't add the salt to the conc. sulfuric. If you do, the chloride from the salt, instead of dropping silver chloride, will immediately be converted to dangerous chlorine gas. In order to drop the AgCl, you will first have to dilute the cooled sulfuric with about 9 volumes of water. ALWAYS ADD THE ACID TO THE WATER!!! NEVER ADD THE WATER TO THE ACID!!! The problem here is that the silver is only slightly soluble in dilute sulfuric. When you dilute, a lot of the silver drops as silver sulfate. Then, when you add the salt, you will end up with a mixture of silver sulfate and silver chloride. This mixture won't completely work with the Karo syrup method.

I no longer have a Hoke book. I do remember that, towards the back of the book, she mentions some INDUSTRIAL processes that are used. I think the dissolving of silver by hot conc. sulfuric acid fell into that category. This was commonly used for hi-silver, silver/gold dore' bars. If I remember right, it was done very hot in a cast iron vessel. Very dangerous method if you're not set up properly to do it. Lots of SO2 fumes, also.

I know that the wide availability of silver plated copper base scrap is like a carrot dangling in front of your nose. I've gone through this myself and can guarantee that the way you're approaching it is no good. The only method I've found that works economically and fairly safely, on some materials, is electrolytic cyanide containing a lot of sodium hydroxide. 

Most silver plated copper scrap runs in the ballpark of 1% silver, about $2 per pound. It's not worth the injuries you could sustain by the method you have outlined.

Chris


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## austexjwlry

Goldsilverpro

Thank you so very much!

I've scrapped the crockpot idea, the crockpot I bought was $3 at a garage sale with the glaze already worn away on bottom from stirring etc. I glad I waited to hear from you to try!

We have a friend here in Austin who has had severe lung problems most of her adult life from cyanide bombing jewelry while manufacturing. She can't even go outside her home on ozone action days! I won't do that.

When I get enough silver plate to send to copper refiner I'll will do that instead. Might try to replate some of the better old items!

One thing I've learned in life is to listen to the voice of experience.

This forum is much better than a book anyday because of people like you!

Thanks again

Wayne


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## Noxx

Mixing conc. Nitric and Sulfuric is also dangerous because if you drop or soak accidentally some cotton in it, you just made a very powerful, shock and friction sensitive explosive ! :shock:


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## Harold_V

GSP--

While I built a stripping cell, it was never put in service, so I have no practical experience to lend to this conversation, but I do have a question. 

Doesn't the original patent discuss the de-plating of silver? Can't the sulfuric cell be used to strip silver from copper alloys? I got the impression it could. The one problem I can foresee is that while it might strip the silver, it won't precipitate it the way it does gold. Any comments?

Harold


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## goldsilverpro

The problem is getting the silver out of the sulfuric, Harold. Check my post above. Big hassle and expense.


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## Harold_V

Thanks, Chris. 

Recovering the silver on copper won't work? 

Harold


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## goldsilverpro

You still have to dilute it first to cement it. With cementation, you'll end up with a mix of silver sulfate and silver metal. Cementation with strong sulfuric won't work because copper is only slightly soluble in strong sulfuric. In order for silver to cement, copper has to dissolve but, the strong sulfuric won't allow it to dissolve. 

Strong sulfuric and weak sulfuric are like 2 totally different acids. Once above about 85%, sulfuric starts doing some unique things.


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## goldsilverpro

I knew the son of a guy that died from cyanide inhalation or ingestion. He was dissolving the silver solder that held the carbide tips on scrap coal mining bits. He was running several drum quantities and working inside with no fume control.

A few rules for cyanide are: Don't get it in your mouth. Don't mix it with acids, even something as weak as coffee. Don't work in a confined area. Don't smoke or drink around it. Don't work over hot cyanide - your skin will break out with "cyanide itch". Wear gloves and a face shield. Get an excellent fume hood

Your friend didn't know or obey the rules. You must obey the rules with cyanide.


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## Harold_V

Hmmm. As I recall, the patent calls for a sulfuric with a specific gravity of 1.65, and is suited to removal of silver. I have no clue of the specific gravity of highly concentrated sulfuric, although I know it's considerably heavier than water. Perhaps it is 1.65. Dunno. 

The process of precipitation on lesser metals is an electrolytic reaction and doesn't really rely on dissolution so much as it does an ion exchange, at least as I understand the process. If there is an exchange, copper will go into solution as the silver is precipitated, creating the illusion of being dissolved. I think someone should give the process a go and see what happens. It could be done on a small scale with little invested. If copper works for recovery, it would be a piece of cake----and residual copper, exchanged by the silver that was in solution, could be recovered from the sulfuric electrolytically as virtually pure copper. The acid could be endlessly recycled, or so it seems. 

This is one of the things I'd have enjoyed working with before I closed the doors on my refinery. 

I understand your comments about the differences in dilute as opposed to concentrated sulfuric acid. It's a strange critter!

Harold


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## goldsilverpro

I think 96% sulfuric has a SG of 1.84. I just reread the patent and it doesn't mention how to get the gold or silver out of the solution.

How can the copper give the illusion of being dissolved? It is or it isn't. The copper can't be obtained electrolytically unless it's dissolved. There is no difference in "going into solution" and "dissolving"? It's 2 ways of saying the same thing.


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## Harold_V

Thanks. I was thinking that the s.g. of concentrated sulfuric was higher than 1.65, but wasn't sure. That's considerably higher than the recommended concentration, and would likely work as I suggested. You're already dealing with a fair amount of water. That also explains why the patent suggested that there might be a loss of physical size when stripping ferrous objects. With highly concentrated sulfuric, that would likely not be the case. 

Precipitation of gold isn't an issue. As the dissolved gold migrates away from the proximity of the anode, it self precipitates. That may not be true with silver, which is known to dissolve in sulfuric without the aid of applied electricity. The question of recovery is the real stumbling block, for it damned well will strip in the typical sulfuric cell.

About dissolution; You're right-----it's either being dissolved, or it isn't. That's true regardless of the approach, be it strictly by acid, or with the aid of electricity. Being an ex-plater, you understand that in ways that others might not, myself included. Electroless nickel works by electricity, but it does not require that electricity be provided-----it creates its own ion exchange to support the deposition. I'm of the opinion that recovering silver from a sulfuric solution with copper will do likewise. 

Each of us knows that copper is not soluble in sulfuric, nor is gold, yet it dissolves when electricity is applied (the ion exchange I spoke of). That's the basis of a copper cell. And so it is with precipitating one element with another. While it isn't truly dissolving in the sense of going directly in to solution, it still goes in to solution via the exchange of ions, it's a matter of having the ion created by an outside source. Bottom line is that it's not necessary for sulfuric to be able to dissolve copper in order for copper to precipitate silver than it is for sulfuric to be able to dissolve gold, or copper, for cells of that nature to function. Both of us agree that a sulfuric cell works----and this is nothing more than the same thing in reverse, sans the added electricity. I'm of the opinion it will work-----and I think one of these guys that feel recovering silver is a worthwhile objective should give it a go. I may be wrong, but nothing I'm reading thus far indicates I am. 

As an after-thought, one might be pleasantly surprised to find the silver self precipitates when the concentration is high enough. The solution will support only a given amount, then it has no options. As I said, this is one of the things I wish I'd have explored before closing the doors on my refinery. 

Harold


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## austexjwlry

goldsilverpro

Before I joined the forum I learned mostly from trial and error!

I tried straight hcl (31% from home depot) on 4lbs of low grade pins from mother boards etc. in a bucket. When it quit working aggressively I presumed I had removed most of the lead etc. that the hcl would remove. It reduced the bulk considerably but left about 3 cups of whitish powder on top of my mostly divided gold.

At that point I switched to dilute sulphuric (about an ounce of sulphuric or even less per 2 cups of water) to remove the remaining tin. But action was slow so I put it in a pyrex pan on hotplate with heat at a very slow boil which made the dilute sulphuric hold a considerable amount of tin etc. After siphoning hot dilute sulphuric with tin I would pour in a 5 gallon bucket. When cool the tin drops out almost completely thus I can reuse the dilute sulphuric over and over while collecting my tin etc. at the same time. 

Adding sulphuric to sediment while hot was dangerous. I fill the still hot pyrex pan with tap water which cools the pan and sediment slightly. Adding while slightly cooler around 1/2 ounce sulphuric acid slowly with very little spattering but it does gurgle some. I let this sit and heat for around 1/2 hr till milky white with dissolved tin etc. then repeat again over and over.

When the contents of my bucket are cool with the tin almost completely settled I siphon into a second bucket without sediment and reuse this dilute sulphuric solution over and over in pyrex pan. 

This method seems a little faster than hcl/peroxide for removoving tin etc. but requires more attention.

This method would be more effective in crockpot because of larger size. Do you think hot dilute sulphuric in crockpot would present same danger of attacking glaze and possibly cracking ceramic etc. ? Would this work on silver plate even if slow?

Thank You for your patience with a new guy!

Wayne


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## austexjwlry

I'm really liking this closed loop dilute sulphuric technique for silver recovery because I'm not generating a large liquid waste stream. Although I'm leaving a finite amount amount of silver etc. in solution at all times, its not lost but will have to be dealt with at some point. Adding additional sulphuric equal to approximately amount of work done is no problem. Might be better to go by ph level?

Just recovering so far will have to clean up sediment at some point and try karo and lye. May wait until I have around a pound or so to fool with.

Have read that reduction to metal is also possible in kiln at way below melting point of silver with little smoke etc. Might try in propane forge!Has anyone done this?

Not sure of cost of materials etc to recover yet or what percentage of sediment is actually silver etc.

Thanks 

Wayne


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## lazersteve

GSP,

On the subject of dropping silver from silver sulfate: Have you tried powdered/granular zinc metal. If so what was the outcome? If not, what do you think of this as a possible percipitant for the dissolved silver in the cell?

I'm not really into silver recovery so this is merely a passing thought.


Steve


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## austexjwlry

The first picture is cell with all water & one cup roto. Worked fast with crockpot on low temp. setting. But kept having to reset battery charger due to resistance of tap water I guess.

The second picture is crockpot cell with liquid fire two bottles (64 ounces)
with one cup water. It stripped silver plating off as fast as I could put it in cell. Couldn't count to ten fast before it was through. Crockpot was on low low heat setting. Using 10amp ,12volt charger on manual setting.

Full strength liquid fire as from bottle was slow; diluting a little makes much faster.

Ceramic hasn't stripped or broken yet.

Third picture is stripped candle holder parts after stripped.

Full credit to Goldsilverpro & Lazersteve as I working off their knowledge and ideas with slight modifications. Goldsilverpro, I very sorry I disregarded your safety info. and did this anyway. I hope you won't hold this against me as I truly respect your opinion! We currently sell more silver than anything as heavy gold pieces just aren't moving. So this silver is pretty compelling.

Wayne


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## Harold_V

Nice work!

I'm curious. What happens to the silver in solution when you leave a piece of the stripped copper alloy behind? (Simply submerged in solution, not connected to anything). Do you see signs of cementing of silver? If you can pull the silver from solution with copper, you'd be well ahead of the game. The silver could be washed, melted and cast into anodes, ready to be parted. I'm still struggling with the idea that it should work. GSP advises that it won't, but I have that little nagging doubt. 

Harold


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## goldsilverpro

This thread has been confusing from day one.

To prove this, one way or another, I would suggest taking a pure silver bullion coin and dissolving a good portion of it in the sulfuric stripper. Weigh it accurately before and after and record the weights. When finished, try to reclaim all the silver from the sulfuric using copper cementation. Compare the recovery weight against what has been dissolved.

BTW, I do really hope I am proven wrong on the cementation. If would be nice to have a simple way to work silver plate.


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## austexjwlry

Harold 

I'll be glad to try and take a picture of the results.

I like the dilute sulphuric cell the best as it automatically dumps quite a bit of material upon cooling. Holding more upon heating again repeating over and over. I'm only using 10amp charger, 20amps or more should run 64 ounce water, one cup sulphuric cell just fine. GSP is absolutely right about hot concentrated sulphuric it's rude and dangerous. I'm not completely sure a thin wall tupperware container would hold up if entire contents of crockpot spilled at once!

With the dilute or concentrated sulphuric cell using copper cathode a lot of mostly silver is built up in blackish sludge form on cathode front and back not really adhered, just wipe off into cell with plastic spoon or you can just remove cathode and wipe build up in container to collect. Just as in gold plate cell once sulpruric is saturated it drops as blackish fluffy precipitate very similar in appearance to sediment in gold cell. Just let settle then siphon or pour off sediment to collect or dilute and filter then precipitate etc.

The copper alloy base material is affected very little in this process. In crockpot size cell I'll have to use a larger power supply to try basket method to deplate more material at one time. With just one small piece at a time in concentrated sulphuric using hemastats to hold as in picture is all my charger will handle. I should try Steve's cell for this with same power supply to note difference in current requirements for deplating silver and gold plate by roughly equal weights. Should be fairly equal.

Like GSP said the cell in Steve's video should work great with a slight dilution of acid with very little water as per GSP's instruction earlier in this thread. I don't believe the glycerin would hurt anything. Dilute or concentrated, hot or cool silverplate is easy to deplate. I think economics of small return was the reason it wasn't done more years ago and now. The process is almost identical in action as when deplating goldplate.

Most of my scrappable silverplate is in storage in country down three miles of very poor dirt road, and we've had historic amounts of rain lately. Might be another week before I can get to it. Stiil much better than
being stuck there wishing I was in town. I'm really having a lot of fun with this!

Thanks for all your help on forum!

Wayne


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## Harold_V

goldsilverpro said:


> BTW, I do really hope I am proven wrong on the cementation. If would be nice to have a simple way to work silver plate.



Judging by the copper cathode Wayne has been using, it appears you are dead right about silver not precipitating on copper from a sulfuric solution. All I can say is "Rats".  

I don't mind being wrong, but it really sucks that it's not a viable solution. Sure is a nice feature when working with silver nitrate!

He has also explained to my satisfaction that the silver behaves much like gold, and self precipitates from a stripping cell, although a small amount remains in solution. I don't see that as a problem, especially if the solution is recycled as you've suggested in previous posts. 

Good call, Chris!

Harold


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## Harold_V

austexjwlry said:


> I'll be glad to try and take a picture of the results.



I'm following you quite well, but it might be interesting for the readers to see what you've done, and how you've done it. Posting a pic is likely a good idea. 



> I like the dilute sulphuric cell the best as it automatically dumps quite a bit of material upon cooling. Holding more upon heating again repeating over and over. I'm only using 10amp charger, 20amps or more should run 64 ounce water, one cup sulphuric cell just fine.
> 
> With the dilute or concentrated sulphuric cell using copper cathode a lot of mostly silver is built up in blackish sludge form on cathode front and back not really adhered, just wipe off into cell with plastic spoon or you can just remove cathode and wipe build up in container to collect. Just as in gold plate cell once sulpruric is saturated it drops as blackish fluffy precipitate very similar in appearance to sediment in gold cell. Just let settle then siphon or pour off sediment to collect or dilute and filter then precipitate etc.



You might consider a water cooled cell. I'm of the opinion, based on your comments, that the silver is precipitating via electronic deposition, although not an adhering film, so the process is likely open ended, as long as you can keep the temperature under control. I'm pretty sure you don't have to allow the silver to precipitate to proceed. Has that been your experience?

Your one statement leaves me with a question. The one about filtering and precipitating, etc.. I would think that the slimes you recover are in need of nothing more than a rinsing in water, then melting and casting as an anode for parting. They should be of high quality silver, although not pure, assuming you're not mixing precious metals. Have I missed something? 



> The copper alloy base material is affected very little in this process. In crockpot size cell I'll have to use a larger power supply to try basket method to deplate more material at one time.



That's in keeping with the patent of the process. It's supposed to strip without affecting the base metals. One thing that is interesting is the wide range of specific gravity of your solution. The patent calls for a given concentration. Looks like it's not nearly as important as portrayed. 

The cell I witnessed was water cooled and used a copper basket. You're on the right track-----but you're going to have to do something about the heat generated, otherwise the cell won't be able to run very long. 



> I think economics of small return was the reason it wasn't done more years ago and now. The process is almost identical in action as when deplating goldplate.



A steady supply is likely more of an issue than anything. It's been known right along how silver can be stripped, but the relatively low value is quickly eaten up by wages, and would likely be the same in today's market. Still, for a guy that enjoys the work, and has a good supply of plated items, the silver can be profit, while the stripped base metals can recover the investment cost. I think you're on to something, but it would be difficult to do for a living. 



> Most of my scrappable silverplate is in storage in country down three miles of very poor dirt road, and we've had historic amounts of rain lately. Might be another week before I can get to it. Stiil much better than
> being stuck there wishing I was in town.



We've heard several reports on the weather in your area. Hope you're doing OK---so many are not so fortunate. 

Harold


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## lazersteve

Harold said:


> Your one statement leaves me with a question. The one about filtering and precipitating, etc.. I would think that the slimes you recover are in need of nothing more than a rinsing in water, then melting and casting as an anode for parting. They should be of high quality silver, although not pure, assuming you're not mixing precious metals. Have I missed something?



I'm not 100% sure what he's seeing is elemental silver. From his description of how it drops when the solution is cooled, it appears to be a compound of silver (Silver Sulfate, Ag2SO4). If this is the case he has another purification step before the melting begins.

I asked GSP a specific question earlier in this topic and his answer seems to support my belief that Wayne is dealing with Silver Sulfate. 

Here's the link to my question :

Silver from Silver Sulfate

and:

GSP's Reply

The silver cell mystery deepens....

Steve


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## goldsilverpro

Here's my general understanding of what is happening. This is what's in my memory bank. I can't find any sources to back me up, in several of my statements.

Silver sulfate, the compound produced when silver is dissolved in sulfuric, is very soluble in concentrated sulfuric acid. I don't remember how soluble, but I seem to recall at least 50 to 100 ozs per gallon. Big numbers. As the H2SO4 concentration decreases, the silver sulfate solubility decreases until, at zero H2SO4 (100% water), the solubility is only 5.7 grams per liter (.69 tr oz per gallon).

Copper sulfate is just the opposite. It is very soluble in weak sulfuric but nearly insoluble in strong sulfuric. I also seem to remember that, the small amount of copper that dissolves in strong sulfuric forms as cuprous sulfate, which is a gray powder, when out of solution.

These solubility numbers can also be called saturation numbers. When a solution is saturated with a certain chemical, no more of that chemical can be dissolved.


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## Harold_V

I read those comments previously, but I failed to grasp the significance. I now realize that I was missing the fact that silver sulfate is soluble in water, unlike silver chloride. It can be compared with silver nitrate in that sense, and I was overlooking that concept. As I mull this over in my head, things are making more sense----a learning curve that I avoided when I refined------a lack of need, really. I was totally comfortable with working with nitric and silver and had no unanswered questions. This is a whole new world for me.

Does silver sulfate reduce to elemental silver by furnace in the same manner silver chloride does? If so, one would than choose to melt with soda ash, and disregard my comments to melt using only borax. You're in a compromising position of encouraging the reduction of unwanted oxides of base metals as one of the costs of recovering the silver sulfide. 

The comment of precipitation now makes sense---

Thanks to all for helping me understand the process better. 

Harold


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## postmako

Noxx said:


> Mixing conc. Nitric and Sulfuric is also dangerous because if you drop or soak accidentally some cotton in it, you just made a very powerful, shock and friction sensitive explosive ! :shock:



This is called guncotton or smokeless gun powder. That is why people must also know that mixing Nitric and Sulfuric acids along with Glycerin as used in the electrolytic cell will create Nitroglycerin which is the UNSTABLE form of Dynamite!


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## lazersteve

Kory,

A member had previously discussed this same topic here:

Nitroglycerin in the cell

Steve


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## austexjwlry

In my silver cells I use Rooto straight from the bottle, no glycerine. I buy it by the case from Ace hardware. They're glad to order it for us as its a guaranteed sale and they're ordering other items from the same company by the pallet anyway.

I don't add water when deplating silver because I like to slow down the action in the cell so as to not create too many hydrogen bubbles. I deplate up to 40 silver plated - nickel silver - base metal items at a time, and perhaps 6 to 8 silver plated stainless knives depending on how many amps I'm drawing per cell. With fresh acid it takes about an hr, when almost saturated around 2 hrs. I reload these cells usually 3 times a day, taking 3 days to saturate fresh acid before I start drawing too many amps. I run 2- 25 amp rectifiers, one for each cell and don't like to draw more than 15 or 16 amps.

When I empty my cells I use a plastic cup or ladle to remove most of the acid and then pour the last little bit into my container. I then use a rubber cake batter spatula to wipe the heavier sludge gently into the container. So as to not splash even small drops onto any part of me. I keep a box of Arm & Hammer baking soda nearby with a cup of water near it. If it does splash on me, I wipe the drop off with a paper towel, then wet my finger and stick it into the baking soda. Then apply the paste to the spot where the acid was to neutralize it, then rinse repeatedly with fresh water. A sulphuric acid burn left untreated will burn and blister much like a burn from a torch flame.

I let the entire contents of my cells settle for at least 5 days as the silver sulfate is very light compared to silver nitrate from a nitric solution. After it's settled all it will, I scoop off the clear dark green sulphuric for further use in my cell. It's still good; I consider it preloaded with buffers.

The remainder is silver sulphate and silver metal from where silver sulphate contacts the copper cathode and is reduced to metal. The sulphuric will only hold so much silver then it starts to self precipitate. You may also have nickel and copper, chromium and iron from the stainless steel items. Perhaps lead and tin from any silver plated pot metal you deplate. Silver plated zinc items deplate fast and are completely dissolved in the time it takes to deplate silver plated nickel silver or stainless items.

I carefully pour the saturated sulphuric sludge into at least 3 times its volume of water. I use the rinse water I used to rinse the items I deplated etc., I precipitate at this time without allowing anything to settle. I precipitate the silver sulphate in solution with a good amount of table salt dissolved in warm to hot tap water. You just add a good amount and you will see a thin light whitish cloud while precipitating. Much lighter with no curds like when precipitating silver nitrate from a nitric solution. It does not agglomerate, forming larger grains like silver nitrate either. Use a definite excess of table salt to keep the silver sulphate from going back into solution while settling overnight. I let this settle a full day then siphon the dark green clear part into a different container.

I pour the clear solution from this container into a 5 gallon bucket which has around 10 lbs of copper scrap or even the nickel silver scrap you just deplated to cement out any remaining silver from solution. Copper and nickel are slowly dissolved by dilute sulphuric acid allowing it to be used for this purpose. I cement out very little silver in this bucket as amost all of it was precipitated by the sodium chloride (table salt).

I pour the contents of this bucket into another 5 gallon bucket containing copper again with virtually no silver cemented out.

I then pour into a 5 gallon bucket containing mild steel where the dilute sulphuric starts to bubble readily and cements out copper with virtually no silver here either.

Yes, I use a fourth bucket with mild steel and get very little copper cemented out. My cementation buckets follow the same 3 day cycle as my cells.

Getting back to the silver sulphate/silver metal/base metal sludge container. I build this up until I have at least 10 lbs because processing 20 lbs is only a little more work than 10 lbs, and 10 lbs only a little more work than 1 lb, but 20- 1 lb batches is 20 times the work of a 1- 20lb batch.

My nitric now costs $49 a gallon and I use as much as necessary to make my wash water run clear. If you leave items in your cell longer than necessary you'll dissolve much more base metal and it's expensive to remove.

Everytime you add nitric to remove base metals from the silver sulphate it doesn't selectively dissolve the base metals like when used on gold. You'll have to reprecipitate some silver in the form of silver nitrate with each wash using table salt . The last few washes I use hydrochloric acid instead of table salt in hopes of removing any remaining traces of lead etc. For my last acid wash I use sulphuric in hopes of removing any last little traces of tin, etc. Then I rinse several times with clean tap water.

I use the karo syrup/lye method to reduce my mixture of silver metal/ silver sulphate/ silver nitrate to silver metal. I like to add the karo first. Now you have to wash again with clean water 10 to 15 times.

Now melt your metal, it'll be close enough to fine if you worked carefully!

Be aware that when old silverplated knives, for instance, are stamped warranted 15 dwt that doesn't mean 15 dwt of silver per piece but 15 dwt of silver per dozen knives. Some very approx. returns from silverplate are:

old tablespoons and forks and large soup spoons 35 dwt per dozen

old dessert spoons and forks, solid fish eaters and fruit knives & forks 25 dwt per dozen

teaspoons 15 dwt per dozen 

coffee spoons 10 dwt per dozen

1 dwt equals approx. 1 1/2 grams

I got these estimates from the book The Sampling and Assay of the Precious Metals by E.A. Smith. Based on my limited experience, I think they are pretty close on old silverplate; newer silverplate items may figure out differently, probably less. Large trays, pitchers, cups, saucers etc in my opinion are best deplated in one piece in a larger cell, as it's really hard to cut them up!

I have not found any appreciable amounts of gold, palladium or platinum in silver plated items even in scrap as far back as 1835, the miners, assayers and manufacturers knew their business!

Best Regards,

Wayne


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## peter i

goldsilverpro said:


> ....Most refiners don't want silver plated items. Basically, silver plated copper is considered as contaminated copper...



Maybe that’s the core of the problem (and the solution).

Cast the plated stuff into ingots, set up a copper parting cell and sell the pure copper. Collect the anode slime, and isolate the silver from it.
Copper plates nicely, so a very simple construction should be possible and workable.
(I have no idea whether it’s profitable or not)

… copper prices should be rising along with the other metals.


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## Harold_V

Unless the feed is quite pure, it doesn't work well. A great deal of the plated items you'd encounter are not copper, but copper alloy. It takes very little contamination of the copper sulfate electrolyte for the copper to begin plating out as sponge, which does not adhere to the cathodes, but falls to the bottom of the cell instead. You end up with nothing short of a mess. 
(Voice of experience, by the way!)  

Harold


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## peter i

Harold_V said:


> (Voice of experience, by the way!)
> Harold



Oh, bugger!

But great to be stopped before trying and failing.

(And this once again shows with horrible clarity, the difference between just writing, and actual hands-on experience with a given subject)


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## Kurr

As I understand it, the issue seems to boil down to the economics of actually melting the Cu. Some one mentioned a propane forge. Thats still gas and you would have to watch the oxidation from it being "tuned". I dont know if he was using a naturaly aspirated or not on his rig. Propane still costs.

I have a charcoal retort I made, very easily, for making fuel for my charcoal forge. I burn at most 2lbs of fuel an hour and can take a 1/2 inch bar of high carbon steel to 1800-2000 F within minutes. 

Powered by a small hairdryer fan, and the extra charcoal act as a reducing agent with proper air control to reduce scale formation on the steel. I get the brush/wood to make the charcoal free and make 20-50lbs at a time.

Could this make melting of the copper aspect feasible on an economic level?


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## Harold_V

I'm of the opinion it wouldn't make much difference. The copper as recovered from scrap steel is quite dirty unless you take measures to remove contaminants. You could process the recovered copper with sulfuric, which would remove most of the impurities, along with the oxides of copper. The oxides that got dissolved could be recovered with more scrap steel, so there'd be no loss of copper, but the problem comes from the need to flux the copper when it's melted. Kennecott fed the recovered copper to their huge reverberatory furnaces, where the contaminants were largely collected in the slag. Their copper came out of the furnaces ready to be parted, with the majority of contaminants being values of other metals. A guy, at home, wouldn't have that option. Their furnaces are shut down only to be relined----so they are in operation constantly. I've stood in one of the furnaces----it's like being in a huge building. Walls are something like 3' thick. 

My experience, having melted and fluxed the recovered copper well, is that the contaminants were not eliminated totally in melting, but reported in the copper. Some did go with the flux, but not enough to satisfy me. From that, I judged that the furnace process must be a prolonged one---giving the contaminants time to oxidize fully and be consumed by the slag. I don't know that I'm right-----but I do know that you will likely spend more money than the worth of the copper by trying to melt it. A cupola may change that----although the copper would still be of poor quality, but good enough to market, considering you'd have a solid mass instead of sponge. 

Might be worth a try with your forge, but remember that copper melts just under 2.000°F, so you'd have to be able to heat beyond that temp in order to pour-----and you'll still need flux because your copper must be in a vessel of sorts (can't be metallic, for obvious reasons). The cupola becomes the vessel, unlike a forge. 

Let us know!

Harold


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## Kurr

Today perhaps, ill rebuild and use a cupola design after i try a run in a crucible. I have clay/sand/wood ash walls that bake themselves into a rock hard refractory so redesign and build to me is basically going to the creek, rebuild and fire it. 

I use borax for a standard flux and has served well in the past for forge welds and some silver/copper alloy i made for a friends knife guard. I use it straight, non anhydrous.

I found also 2 companies that offer to buy copper sponge. 

We purchase Copper Ore and Copper Materiel - 09 Apr 2008

We purchase Copper Ore and Copper Materiel

Copper scrap, copper mud, copper dust, copper sponge (The copper content should be 4% min).

Copper slag, copper and cadmium slags (The copper content should be between 3% to 20%).

We purchase copper ore, copper concentrate, copper materiel (The copper content should be more than 5%). Molybdenum Materiel (The molybdenum content should be more than 2%).
Web address: http://www.antimony-cn.com
Address: No.90 South Jingxing Street, SY, China
Phone: 86-24-25442052
Fax: 86-24-25442011

That one is on bikudo.com and i think this one buys as well.

http://www.exporters.sg/view_rfq_txn.asp?rfq_id=47089

Hope it helps in determing a profitable way for plate.


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## SapunovDmitry

Yay! I tried the silver cell! Though it wasn't a great difference compared to a gold cell, i got nice copper wire. But it was SO long and SO stinky, that i will think twice before running this type of cell again. Or maybe something was wrong? I used dilluted sulfuric as it was shown on the first picture. I didn't use regular water, it was distilled. But thanks alot for this tutorial. I will try strong sulfuric like in the gold cell after holidays and post results.


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## Harold_V

SapunovDmitry said:


> Yay! I tried the silver cell! Though it wasn't a great difference compared to a gold cell, i got nice copper wire. But it was SO long and SO stinky, that i will think twice before running this type of cell again. Or maybe something was wrong? I used dilluted sulfuric as it was shown on the first picture. I didn't use regular water, it was distilled. But thanks alot for this tutorial. I will try strong sulfuric like in the gold cell after holidays and post results.



Your post is somewhat confusing. If you tried a silver cell, the electrolyte should have been silver nitrate, with no sulfuric acid included. 

Were you making reference to a copper cell instead? 

Harold


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## SapunovDmitry

Well.Actually the stuff mentioned above was sulfuric cell.
I tried it exactly as it was mentioned in the post with three pictures. I tried sulfuric cell for gold before and i liked it (But it was concentrated there).
No.It wasn't nitric.Nitric would be stinky from the begining.  
This one didn't smell good only during the process. When i get to my camera tomorrow, i will make a shot of a deplated wire.

Btw. I found some old russian books about deplating and refining.In the copper ore refining section they mention that 1t. of copper could carry up to 10 kg of silver and 300 gramms of gold (They say that they have to be separated(well, they are right  )). That's why they says that ore is melted, divided into plates and placed in the elecrolysis system, that uses 0,2V(kind of a "magical" number) and currents up to 250 A per m2 :shock: and fairly dilluted sulfuric as the electroylte. Silver/Gold precipitates, cleaned and treated as Dore metal.
Now,the main thing.
It says that you must have about 30-50 kg of Cu per m3 of solution and 150-200 kg of sulfuric per m3. Certainly it can be scaled, though.


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## goldsilverpro

I assume you're speaking of the 3 photos on this thread from Jul 5, 2007. He was using concentrated sulfuric in the 1st 2 photos. He diluted only very slightly (maybe 5% water, by volume) in order to speed it up - as he described. If you diluted too much, the silver won't strip at all. I would guess the limit is about 65/35, conc. H2SO4/water, by volume. Ideal would be 95/5, conc. H2SO4/water.


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## Harold_V

Sorry. I misunderstood your post. I expected you were talking about a parting cell, not a stripping cell. I gather the copper you mentioned is the wire after stripping. That makes sense. 

Harold


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## SapunovDmitry

Yeah.You are right.It didn't strip until the solution was i would say 15/75. But then the current began to grow very fast. I did nothing, but it grew from 2 amps to 8-9 amps.And the solution became blue colored. That was my bad, somewhy i just forgot about concentration.
Thanks,guys.  

I will try again and post results.


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## gorfman6154

Bump. :mrgreen: 

Gorfman


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## Palladium

Meow


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## SapunovDmitry

Ok, i always keep my promises, so yesterday i've sent my girlfriend to the bakery and started chemistry.
I took about 80 gr. 35% sulfuric acid and poured it in the Pyrex breaker. Then i tried to find some lead, but i was rather limited in time while my GF was buying bread so i took SS stick (the cathode).
I took my charger set it on 12V. I had some silver plated RF contacts so i've thought that they could be well used for this purpose. I took one as an anode and started deplating. At first the current was about 1 A, but in 30-45 sec. it has rapidly risen to 5-6 A. (I think the copper layer was exposed to acid by that time). I ended with shiny copper contact as can be seen on the picture below and flakes of copper and silver in the acid (white and slightly green). I was so happy, that forgot about my GF returning from bakery. I was unable to get silver from solution because my GF started kicking my /// for experimenting at home. Anyway i have no idea how to get it from the acid without making the solution unusable again. I think the only way is to make it settle for some days, filter the white powder out and then let acid stay for a while like it says in Ammen book with copper and SS electrodes. What do i do with the silver/copper salt then? What flux should i use to regenerate it to copper/silver alloy?


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## seawolf

I am still a noob and I have been reading a lot. My question is once you have the silver metal and silver sulphate would it be possible / advisable to dry the silver then digest with a 50 / 50 nitric and precipitate the silver with a copper bus bar or heavy copper pipe cut and flattened into a sheet? Then melt the silver and pour an ingot / ingots for refining in a silver cell?
Mark


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