# deplating silver plate with sulfuric acid



## rbramsey

First, I am new to this forum, but I have been refining e-scrap on and off for years. I still consider myself a neophyte. I have been reading posts on here for several weeks, and have noticed that yall use Hoke's book. I learned how to process with Ammen's book "Recovery And Refining Of Precious Metals". In the past, I never fooled with silver because is was too cheap, and cost too much to process. Now, with silver on the rise, I dug around and found 100+ pounds of silverplate wares and wire that was kicked aside.

Anyway, I always been told that its not worth the effort to process silver plated items. I have read several post on this forum that simply state it costs too much. With both copper and silver on the rise, at what price would silver need to be to process.

Can someone help me put a ballpark price on the recovery and refining?
What is the rule of thumb on the amount of silver on plated items? I was thinking 1%, but that seems high.
What method would be most profitable? electrofining, Nitric bath, or ...

Thanks
Richard


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## nickvc

Welcome to the forum.
There really isn't a cost effective way of recovering your silver off the plated items that I'm aware of. The main problem is that much plated ware is over copper and brass,a copper alloy, and anything that will dissolve silver will dissolve them,even cyanide stripping has the same problem because as soon as the copper is revealed it's attacked.
The only way to recover the silver in my opinion is to melt it into bars and use them for cementing silver solutions but unless you refine a lot of material regulary it's a long drawn out process to get the silver back.
Conecentrate on easier ways to earn money or recover values and if you really want to recover some money from your plated goods put them on bay and wave them goodbye.


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## Harold_V

The one option that has not been addressed well in all the time we've talked about silver plate is the one whereby silver is stripped by a sulfuric cell. With it, silver can be removed, saving the base metal for sale as scrap. 

The sulfuric stripping cell was developed to recover expensive machined parts that required plating, where the plating was defective, but the part was good. Therefore, it's the most logical way to recover the values so long as one is processing metals that lend themselves to the process. 

The big problem is recovering the silver from the cell. With gold, because it isn't dissolved by sulfuric, it self precipitates after it leaves the proximity of the anode, where sulfuric is converted to pursulfuric acid (assuming I have it correct). Silver does not display the same characteristics. 

One of the things I have long considered is the possibility that the sulfuric may become saturated to the point where it, too, may precipitate. Our resident authority on this subject is GSP, who has considerable experience with the cells. He has never alluded to the concept I suggest, so it might be nice to hear from him, or anyone that might offer a reason why the suggestion isn't worth consideration. 

I expect, when all other avenues have been exhausted, that silver removed by that process could be recovered by cementation with scrap iron. Who knows---copper may even work, considering it does not dissolve in dilute sulfuric.

Harold


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## goldsilverpro

I don't know any more than you do about this, Harold. I have never used the sulfuric cell for silver. As with you, I would be concerned with getting it out. I do know that the solubility of silver sulfate tapers off quickly as the sulfuric is diluted. You could get more dissolved if the sulfuric were not diluted at all and no moisture were allowed to enter from the air. I would think that the chemistry of silver recovery would be the same as the old production method of dissolving silver in dore' bars in hot concentrated sulfuric in a cast iron container. If I remember right, this process was covered quite well in Rose's, "Metallurgy of Gold".

Since, at present, there is no good method for the recovery of silver from silver plated materials, I would suggest that someone experiment with this using the sulfuric stripper.


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## rbramsey

Harold, sounds like the approach I was taking. I wasn't sure about the efficiency, but that's what experimenting is for. The method I used:

1 gallon of Napa battery acid with 10 ml of glycerin. I didn't use coppersulfate to load the solution. First I used 12V with success. I noticed that the silver was going into solution with I nice thick gray cloud. After about 10 minutes the solution started to pull about 50 amps and held steady. Gassing off pretty good. The solution was around 60 F. I let it run for about 20 minutes, and shut it off (the cables were getting warm). I could see fine silvery particles floating around. I was using a copper rod to stir and poke with when I noticed it was cementing silver out of the solution (I wasn't expecting this). I left the copper rod in the solution over night, and there was a nice pile of silver formed underneath the copper. I also noticed some small clumps of silver crystals in the solution.

During a few other experimenting sessions, I used 6V and the silver didn't seem to want to go into the solution as easy. I didn't have a variac to use too to control the precise voltage.

I will try to get some time this weekend to "experiment" some more. I will weigh the plated flatware, strip the silver and weigh again. I am try to determine at what point is it worth processing silver plate. 

Another process that I was thinking about, was to melt copper based items and to solar-electrofine. I don't have another plan for the brass based items yet. Speed is not a concern, most of this has been around here for more than 15 years anyway, but cost is.

Many years ago, I met a man using Sodium Hypochlorite to leach out PMs at an old incineration site. The process would take months. He would fill a plastic barrel with ash, several pounds of HTH (I dont remember the exact amount). He kept the barrels laying on their sides in the back yard. A couple of times a week he would roll the barrels around. After a few months he would drain the liquid, test, and process. We talked back then about silver plate, but at the time silver was too cheap. I have been trying to remember the exact process, but some of the details are blurry. 

Richard


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## goldsilverpro

The Napa battery acid is only about 35% sulfuric. With this, you will readily dissolve copper and I would think this would quickly shorten its life. The standard cell for stripping without attacking the base metal uses sulfuric of about 91% to 95%, by weight. Some of the available drain cleaners are sulfuric of that strength or, there is a lot of discussion on the forum for increasing the strength of the battery acid to a usable level through heating and evaporation. You will also have to control the amperage so this solution doesn't get too hot. I always kept it below 120F. Otherwise, you can dissolve base metal and create a mess. You don't need any glycerin.

The idea is to strip the silver without dissolving base metals. This can only be done with the strong sulfuric and by controlling the amperage.

Melting and electrofining requires a fairly pure copper to start with. When zinc or other metals are present, you will find that the deposit at the cathode is very unruly and can quickly become impossible to work with. It might work fine for an hour or two or three but you soon will have a mess.


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## rbramsey

Thanks, I'll try full strength sulfuric acid next time. I do see copper forming after 10-20 minute run on the cathode. 

As far as determining the correct amperage, will heat generation be good enough. ie. If the solution is rising in temperature too much amperage. If temperature is steady amperage is good?

As far as the electrofining option is concerned, I could not find any good numbers on a rule of thumb number to use for silver plate. In back of my mind, I was thinking around 1%. I thought the copper base would have been high enough purity to handle that amount of silver. If not would adding something like copper electrical wire or copper from armatures help.

I am trying to figure at what price would silver have to be to break even. I do believe this information will be very relevant in the near future. Silver plate can be picked up relatively cheap at the moment.


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## goldsilverpro

Maybe this will give you an idea of values. It they aren't marked, a pure guess of 1% might be used. At least, a lot of other types of silver plated materials run about 1%.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=8451&p=78809&hilit=federal#p78809

If you use the strong sulfuric and if you keep the current and temperature down and if you pull the part out immediately when finished and rinse and dry it quickly and if your scale will read to .01 grams, you might be able to weigh a piece before and after stripping and get some idea of the silver weight. I would think this is best done with a fresh solution.

Especially, if your setup is small, I would control the amperage by the temperature of the solution. I'm really not sure what the max temp could be. I do know that a lot of people on the forum have had big problems when they allowed it to get too high. I didn't ever go over 120F, but you may be able to go a bit higher, say, 130-140. If you get a lot of coppery sludge and/or a lot of garbage forming on the cathode, cut it back.


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## Harold_V

I've talked about my experience with a stripping cell previously. I was flown to Pueblo, Colorado, by a customer that wanted me to build a stripping cell for him. While I didn't witness the cell in operation, I did talk to the gentleman that operated the cell. Theirs, like the one I built, was water cooled by a jacket that surrounded the cell proper. That particular cell was operated with a power supply capable of providing up to 28 volts & 300 amps. Heat was a serious consideration, for at elevated temps, base metals could be dissolved. 

Some rambling thoughts, in no particular order. 

Conductivity falls off greatly as gold is eliminated, but I can't speak for silver. It could be that with proper balance of electrolyte, temperature and voltage, one can (and should be able to) determine when all of the values have been eliminated. I was lead to believe that amperage falls off drastically when that is the case (with gold). That may not be the case when one is stripping with an electrolyte that is too diluted---and reports become VERY conflicting in that area. It is well known that copper will not dissolve in dilute sulfuric acid, although it will dissolve in heated concentrated sulfuric.. Therefore, why it gets dissolved in this case is a bit of a mystery, although conditions do somewhat emulate those of a copper parting cell. 

I had never experimented with recovery of silver from a sulfuric solution, but I had read that slimes from the silver cell were digested with concentrated sulfuric in a cast iron vessel, to remove the excessive silver that is contained within. I know that a great deal of silver remains as finely divided particles in the slimes, thanks to my many experiences of parting silver over the years. 

I had expected that silver would cement with copper from a sulfuric cell, so I thank you for the confirmation. The only thing that remains, now, as far as I'm concerned, is to determine if you can strip the silver economically, and know when it has been fully stripped. In most cases, the base metal beneath silver plating is so close to the color of silver that it may be difficult, if not impossible, to determine its presence, or absence, by visual means. It could require a test with Schwerter's solution, which is fast and sure. Eventually one would know, from the time in the basket, if there was any value remaining. 

On the subject of baskets, I was informed on my fact finding trip that a basket was withdrawn, dumped, and re-loaded once for each lot that was stripped, insuring that any surfaces that may have been in intimate contact with other surfaces were exposed. 

A basket made of heavy copper mesh screen should be more than adequate for stripping items such as this, for, under normal conditions, base metals are not attacked by the cell. Were that not the case, it would not have been successful for its intended purpose, that being the salvaging of expensive components that had unacceptable plating applied. 

I think it can be done, and, as Chris said, lose the glycerin. It is not a required component. 

Ok, gotta go. I'm helping my wife peel some chestnuts for the dressing for our turkey. If you've never had that kind of dressing, you have no idea what you're missing!

Have a nice Thanksgiving, guys. 

Harold


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## Palladium

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=50&t=267&start=40


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## goldsilverpro

I would think that the amperage would fall and approach zero when all the silver has stripped, just as with gold. Since the base metals don't dissolve, it is the absence of gold that creates this phenomenon. It would be the same with silver. If the sulfuric is diluted in an electrolytic cell, copper will definitely dissolve.


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## butcher

? if only silver removed and would fall to bottom as powder, decanting acid, then wash crystals. why dilute?


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## Ian_B

what about just dissolving the base metal if your dealing with Electroplated Zinc? 

snap a silver plated item into smaller pieces to expose the Zn base metal then place into a container and add HCLaq to cover and then when Zn is dissolved wash the remainders thoroughly. Melt the remaining metal and then process with nitric to purify? (plus other purifying steps after)


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## Harold_V

butcher said:


> ? if only silver removed and would fall to bottom as powder, decanting acid, then wash crystals. why dilute?


My concern is that the silver may NOT fall to the bottom, but stay in solution. If it were to precipitate the same way gold does, it should be a non-issue recovering silver with a sulfuric stripping cell.

Chris mentioned that he expects amperage would fall off as silver was exhausted from the anode (item being stripped). Again, my concern would be that silver may stay in solution, increasing conductivity, so that may not be the case. 

I sure as hell wish I had the cell I had built so I could experiment. This is one area I never explored, but always had questions. 

Is anyone willing to conduct some experiments for the good of all readers?

Harold


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## lazersteve

I'll put this experiment on my list as I've always been curious how the entire process would work, plus I have some silver plated scrap on hand to test.

Steve


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## rbramsey

From my limited experience with stripping cell, the amperage didn't seem to change much from start to finish, but I will watch this closer on the next run.

Also, another observation, the silver both dropped as slime and went into the solution. I was able to cement out the silver in solution with copper. Remember I was using 35% sulfuric acid. I haven't had time to make a run since GSP told me to use 98% sulfuric. I'll try this tomorrow.

Something else that seemed ironic was GSP said that the copper would dissolve in the dilute sulfuric acid, and I didn't seem have a problem with the copper until he told me I would. The last run had the copper building on the cathode quicker than silver coming off.

I will use the advise given and report back. 

Thanks, Richard


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## Goldfinger4

Still waiting for your report 

I am also currently experimenting around with a sulfuric acid cell. I use plated spoons, 37% sulfuric acid and a stainless steel electrode.
Up to now is did nor notice any AgSO4 crystals at the bottom of the container. I don't understand why this should happen - silver permanently dissolves at the steel electrode.
I know when it's ready when I see the electrodes sediments changing their colour to dark brown. Then of course I have copper impurities but it seems to be too difficult to get pure silver in the first step anyway.
I also tried to melt the silver of from plated brass. The melting temperatur of brass is above 1000°C. With a temperatur of 985°C all silver flows to the bottom of the melting pot. This is clearly visible as the brass is covered by red copper oxide. Be careful not to inhalate zinc fumes.
The purity of the silver is about 40-50%, mainly polluted by zinc and brass material because the furnace is always hotter at the bottom and there some brass will be melted. I let the spoons in the pot for around 15 min. Maybe less than 15 min would be possible. My furnace runs on 700W.

Btw in Germany there are companies that buy plated brass stuff for 15 Euro/kg. So there must be a lucrative way!
http://www.scheideanstalt.de/ankauf/tafelsilber/aktuelle-ankaufspreise/

Regards!


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## joem

This issue has been running through my brain for a while; If silver can be attached to an item then logic states it can be removed.
Here are a few things I have come up with:
using a brush in water to manually remove the silver
http://www.youtube.com/watch?v=I2igGhOjfcg at about the 51 second mark
Then filter the silver out , dry and run through a crystal silver cell
or this 
http://www.ehow.com/how_4898690_remove-silver-plating.html
or a chemical to strip such as what is listed in the msds for silver stripper
http://angelgilding.com/media/products/Silver_Remover_MSDS_C1016.pdf
http://angelgilding.com/media/products/Silver_Remover_MSDS_C1015.pdf
http://angelgilding.com/media/products/Silver_Copper_Mirror_Remover_MSDS_C1047.pdf

I have also found;
Dissolve 4 oz/gal sodium nitrate in concentrated sulfuric acid. Electrostrip with a lead cathode at 3V, 70-120F.
*******************************************************
and I have tried soaking in litho fix but this does not work

Now realise I am NO chemist and your questions can not be answered by me so I leave it to the people on this forum with more knowledge about these chemicals.


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## nickvc

Goldfinger4 said:


> Still waiting for your report
> 
> Btw in Germany there are companies that buy plated brass stuff for 15 Euro/kg. So there must be a lucrative way!
> http://www.scheideanstalt.de/ankauf/tafelsilber/aktuelle-ankaufspreise/
> 
> Regards!



It's possible that they are using either a cyanide stripper,which many on the forum don't have access to, or they have a deal with a large copper refiner to supply low grade bars to be refined. Do they buy e scrap? If they do I think the latter may well be the case.


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## Goldfinger4

@joem:

The Brush method will not be useful for larger amounts. Maybe it could be possible to use a washing machine with stones or sand inside. But because of copper having the same robustness as silver, this will not deliver a pure result.

As far as i know, NH3 does not dissolve elemental silver and is only used to recover silver from its salts. I thought of using NH3 for an electrolysis but it smells too ugly^^

I do not know a method using FeCN6-ions, the iron-cynide-complex is very stable and why should the iron ion be replaced by elemental silver.. but our goal should be to handle the silver without using any kind of HCN.

Every method using nitric acid (NaNO3 + H2SO4 = NaSO4 + HNO3 + H+) will cause unhealthy NO2 fumes.
Did you try the electrolysis with sulfuric acid and sodium nitrate? Did you smell NO2?

@nickvc:

People in this forum say, that cyanides would dissolve copper the same way as silver. It would only be possible in a very basic environment (Cu builds CuO).
I think your assumption with the copper refiner is right.. they will melt it together with other copper scrap and use the copper electrolysis.


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## rbramsey

I have been busy on another project with silver. I rigged a computer P/S so I it can be used. This will give me [email protected], [email protected], and [email protected] I had a hard time locating 97% sulfuric acid. So, I started by evaporating battery acid down. I need to find out the profitability of recovering the silver from plating so I can move forward on this project. If it is not profitable yet, then at what price does silver need to be. 



Goldfinger4 said:


> Still waiting for your report
> I am also currently experimenting around with a sulfuric acid cell. I use plated spoons, 37% sulfuric acid and a stainless steel electrode.
> Up to now is did nor notice any AgSO4 crystals at the bottom of the container. I don't understand why this should happen - silver permanently dissolves at the steel electrode.



When I used 37% sulfuric acid, the silver went into the solution. I would see it immediately. I was using a [email protected] The cell ran a constant ~50A. The cathode was lead. The copper was plating out to the cathode. It would take 10 minutes to deplate a bowl. After about an hour or so it would seem to stop working. The electrolyte was full. I cemented out the silver with a copper bar. I was able to start up the cell after that, but it wouldn't work as well. This is when GSP told me I would have problems trying this way. Since then I have been getting supplies together to doing right.



> I also tried to melt the silver of from plated brass. The melting temperature of brass is above 1000°C. With a temperature of 985°C all silver flows to the bottom of the melting pot. This is clearly visible as the brass is covered by red copper oxide. Be careful not to inhale zinc fumes.
> The purity of the silver is about 40-50%, mainly polluted by zinc and brass material because the furnace is always hotter at the bottom and there some brass will be melted. I let the spoons in the pot for around 15 min. Maybe less than 15 min would be possible. My furnace runs on 700W.



How clean is the brass when it comes out? Is it clean enough to sell as brass? The few pieces of brass plated silver was yellow brass, and there is some other white metal on it. It couldn't be sold sold as brass.

With some finagling, I got the copper pieces are clean enough to sell as #1 copper. It is not practical to do on a larger scale. There is too much labor involved.
Richard


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## rbramsey

joem said:


> using a brush in water to manually remove the silver
> http://www.youtube.com/watch?v=I2igGhOjfcg at about the 51 second mark
> Then filter the silver out , dry and run through a crystal silver cell



This is similar to what I thinking as another approach, but better. I was looking at using an enclosed bead blaster to blast off the silver. After a while, mix the beads with nitric to remove the silver and copper. Another Idea, was to use an air scaler or wire wheel to scratch off the silver. These approaches used a lot of labor. The last approach would be to smelt the plated copper to cast anode bars and electrofine the copper, and catch the silver as slime.

Richard


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## Goldfinger4

I tried the copper electrolysis with plated stuff. It did not work, silver also dissolved though my voltmeter only displayed 0,4V.

Maybe the melting method can be improved. From one fork and two spoons I recovered 8g silver.
I will try heating to 920°C. Maybe the gaseous zinc breaks up the silver plating and it can be easily removed.
I report on weekend.

I found someone to buy brass metal. I don't know if he would buy it covered with copper oxide. But it would be no problem to melt nice ingots for selling.
CuO has a high melting point and can easily be removed from the molten metal.


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## Goldfinger4

Heating plated brass to the boiling point of zinc did not remove the silver plating.. it somehow went through the hot silver and covered it with an oxide coating.

Any news about your deplating project?


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## goldsilverpro

With time, the copper will migrate up through the silver. This is greatly accelerated with heat.


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## Goldfinger4

So this is my new silver deplating cell.
The anodes are 6 plated forks, the kathode is stainless steal. In the big bowl you can see fresh silver, dried silver is in the smaller bowl.
The electrolyte is 2l of 37% sulfuric acid and a little bit nitric acid. It runs on about 2,2 V and 23-26 A. I tried it on 5V (4,2V at the electrodes) but it produced acrid smelling colorless gas (maybe SO2) so that I can not use this higher voltage, although the 50-60A could have speeded up the reaction. 

I don't want to produce pure silver, 50% purity would be enough. I found a metal refinary nearby that offers to refine 30kg of raw material for 550EUR and gives me nice stamped silver bars back.

Did you make any new experiences? What voltage do you use now?


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## Goldfinger4

After 9h: 16g raw / 12g silver measured by AgCl-method


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## Lonnie

Harold wrote 

"" Is anyone willing to conduct some experiments for the good of all readers? "" 

I certainly am willing and ready . I'm new to doing this so I'm not to sure of how much help I could be but willing to try if it might help me reach my goals . L et me give you some back ground on myself . My names Lonnie and I'm residing in Middle Tennessee . I happen to have quite a bit of silver alloyed contacts and about a 100 pounds of copper with a heavy coat of silver plate . 

So I've been trying to come up with a way of removing the silver from the contacts as well as from the plated copper . I bought instructions on ebay LOl using sulfuric acid and sodium nitrate to plate the silver out into solution . It's suppost to turn the electrolyte red and when done you drop the stuff with common table salt . 

I started with some electrical items I have with a heavy silver plating on them . Using a battery charger it was blasting the silver coating off in tiny flakes and white junk was forming on the plated piece blocking the DC current and it would stop working . 

So I pulled out a toy I bought at another auction and when I put the current to it this time it started turning the electrolyte white about like milk . I let it go and in a few minutes stripped the silver from a few pieces . Then it started precipitating into white chunks that soon turned purple . 

Could this purple stuff be AgCl ? From reading in here I see the people with more experience advise staying away from AgCl if that is in fact what I have . btw I'm completley new to this so If trying to help I need things explained a tad bit better than most . I am trying to learn as I go and use terms like AgCl and not Silver Chloride . So dont assume I have a back ground in chemistry just because I do that . I just figure I'll learn these things if I use them as I advance my knowledge in this area .

Things I'm using and facts I've observed so far . 

I get my sulfuric acid from old car batteries ( it's free ) . Trying to cut cost as I'm aware theys not much money in removing silver plating . I figure lead could be in this so I cook my AgCl ( if thats what the purple stuff is ) in a crock pot for 4 hours , filter while hot and repete this again . I did get about 1/8 inch of a white substance that settled in my first wash water I'm assuming is lead . Plus my first wash had a slight blue tint to it . My second wash came out crystal clear with no white substance settling in the bottom . 

Sodiun Nitrate I have to purchase on ebay . The electrolyte plays out rather fast but filtering seems to make it work good as new again . It is becoming contaminated with copper that I hope I can figure a way of removing so I can keep using the stuff . 

Per the ebay instructions I use a lead fishing sinker as my cathode . Another reason I figured a little lead in the sulfuric acid shouldn't be a problem . Copper does collect at the cathode but I'm able to collect most of this with a snipper bottle . 

If this white milky stuff that turns purple is the silver then it's easy to remove from my electrolyte . It falls out by itself simply filter the stuff and the electrolyte is ready to use again . However if it is the silver it's in the form of AgCl that the most experienced in here advise staying away from . 

Plus I'm getting a silver looking substance also . I haven't tried melting any but it appears to be little chunks of silver metal . Oddly enough I only get this in my wash water . What I do is sumerge the plated piece and hit it with DC current . After a few minutes I remove it and dip in water and use a brush on it . If all silver is gone I'm done with that piece if not I give it more DC juice . I'm assuming the silver looking chunks are plating that was loosened up by the current and knocked off by the brushing . 

A little information on my DC power supply . 

I'm using a toy I bought at another auction . It's called a 

EBERBACH Electro-Analyzer 1000

Electro-Analyzer 1000 
Eberbachs Electro-Analyzer 1000 apparatus is the laboratory standard for determinations of lead, nickel, copper, zinc, antimony, cadmium and other metals by the electro-deposition process. 
Unit has a finished steel case (30 high) with stainless steel front surface and occupies a table space of 15 x 17. The front panel protects the apparatus from corrosive spillage and fumes. No electrically corrodible components are positioned where material may fall into the cell and alter results. 
The unit delivers up to 10 volts, 10 amperes DC at each of two positions for simultaneous determinations. Separate ammeters (0-10A) and center-zero voltmeters (10-0-10V) indicate amount and direction of current flow at each position. Polarity reversing switches change the polarity of the electrodes. Current to each position is supplied by individual power transistors controlled by potentiometers. In line fuses protect AC and DC circuits. 
Stirrers are driven at a constant speed of 620 rpm by a split-phase induction motor. Hollow spindles permit easy vertical adjustment of the glass stirring rods. Power to each stirrer and entire unit is controlled by individual switches with pilot lamps. 
Heavy-duty platinum electrodes (45 mesh) are recommended for this unit. However, lighter weight electrodes may be used. Spring loaded electrode holders grip the electrodes without deforming the stem and may be moved horizontally for centering nested electrodes. For rotating anode techniques a stainless steel rotating anode holder may be substituted for glass stirring rod


My goals 

I seriously doubt I get rich or make any money doing this . Thats one reason for my need to do cheaply as possable . I'f I could just say I refined and purified this bar to 99.999 fine silver it would be payment enough . 

So my thoughts were to get it pure enough the first time to run it through a thumb cell and clean it on up . Any help reaching this goal is greatly appreachated . If I can conduct experiments that may help all the readers that would be great also . So you know who I am and what I'm trying to do . If you have an idea you would like for me to try just run it by me . If I'm able to I'd be happy to give it a try . 

Thanks 

Lonnie


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## lazersteve

Lonnie,

The white stuff that turns purple is AgCl= Silver chloride.

Your cell electrolyte is a crude form of nitric acid. 

You should check out the Guided Tour Link below for several useful links to terminology used here, General Reactions, Safety, Forum rules, etc.

The copper colored stuff at the cathode is copper metal. The silver colored stuff at the cathode is silver metal.

The real problem with your cell is the electrolyte. It's an impure form of nitric acid which leads to salts like sodium sulfate, copper sulfate, silver sulfate, and a mix of other stuff. It would be best if you take a break from running any cell or experiments until you get a handle on what methods work best for the scrap you want to process.

Take some time and read Hokes book and the links in the Guided Tour.

Steve


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## Lonnie

Steve 

Thanks for the reply it's good to at least be certain the purple stuff is indeed AgCl . The silver metal like substance never came from the cathode it was brushed from the anode in my wash water . I have took a break running it with the exceptions of small experiments on other material I have removed over the years . My motto has been if you do not know what it is then DO NOT sell the stuff . The real reason for the break is simply that I nered to do other things plus after reading yesterday that I should avoid AgCl if at all possable put an end to me producing that . 

Speaking of safty I do like the fact that my process doesn't appear to gas off any silver dioxide ( I think ) thats the name of the red / brown deadly gas produced when silver is digested in nitric acid . It may be making small amounts but when covered with a sheet of glass I see no red/brown gas building up . 

I kinda like that idea as my work station is outside in my mill house ( no lab ) type facillity to safly do this in . I do train a fan on the cell and approach it from the fan side always making sure any fumes produced are blown away from me . Still if I could come up with a process that doesn't actually digest the silver producing the silver dioxide gas I'd prefer that process . However I dont want a form of silver thats trouble to melt or just as toxic . I've been reading a little on silver oxide as I think it gets on the anode if I let it set running to long . Sometype of brownish black looking film starts building on it . 

So yes I agree it's time to stop running the cell and learn a few things . I worked on a kiln and a thumb cell today . I have everything needed to build a small kiln and will concentrate on this while reading . Plus gathering up things to make a good cell from once I get it all ironed out a little better . Thinking I'll use a scrap coffee maker I have . The sides arn't sloped like the material I've read suggest for easy removal but it is made in such a way the removal of crystals should be fairly easy anyhow . It's about 20 inch long and maybe 12 inch wide . It's not as tall as I invisioned I'd like but still I think it's a good quality start for the price ( free ) . Too good of a start not to take advantage of the professional welding and construction . 

Sure it has it's pros and cons but already constructed of food grade stainless and it doesn't leak . It has one hole in it where the electrolyte could easily be drained for cleaning of Ag crystals via a chemical resistant valve . It's a little bigger than I'd like it to be but not so big I couldn't make due with it . 

I will take the tour and read the material you suggested . Will probably be Tuesday before I can get back on line to begine this . Again thanks for the reply and all help is appreachated .


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## Goldfinger4

Hi Lonnie!

The main principle in dissolving silver is a redox reaction. That means, you either need a material that is more attractive to electrones than silver and steals them (like the nitrate ion from nitric acid) or you steel electrones by connecting the silver to the positive pole of a power supply. 

I don't understand you method.. it looks like a mix of both.. you are using a power supply, so silver should be the positive pole and move to the negative pole where you can recover it as a mass looking like a sponge or small crystals. Of course, some silver remains in the sollution but that's no problem because you use this sollution for a longer time. There is no need to recover it whith table salt because afterwards you can throw you sollution away. When the electrolyte is contaminated with chloride ions a silver chloride layer will form on your plated material and hinder further reactions (or did you make other experiences?).

Table salt is only needed when you dissolve silver in nitric acid (sulfuric acid + nitrate salts = nitric acid).

A useful method for producing 999 pure silver is:
1. deplating in sulfuric acid cell
2. dissolving the relatively impure silver sponge in nitric acid and use the table salt method, making raw silver bars als electrodes
3. running a silver cell with silver nitrate electrolyte

I decided for myself that I stop after step 1 and sell the raw silver to a raffinery. Steps 2 and 3 pruduce toxic gases and waste and cause costs, nitric acid is expensive. And it is working time expensive..


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## colibri

Regarding the removing silver plating in 37% sulphuric acid, I have been reading the posts with interest and thought Id have a go. Ive got a lot of old electronics bits that are silver plated and always wondered if it was possible to recover the plating.

So using a stainless cathode I have managed to de plate a few items, I found that the cell current was very low until it removed the silver and when it hit the copper underneath the current shot up. Now I have a cathode covered in a dark brown sludge and the sulphuric is a cloudy light green colour. Am I doing it right? 

Im thinking I should now be able to cement out some of the silver using a copper bar. I guess there is a large quantity of copper in the sulphuric, would it be possible to cement this out using iron?

cheers

Anthony


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## Goldfinger4

Electrolysis is a continous method. There is no reason for cementing out copper or silver. Simply use the electrolyte for the rest of your stuff and collect the dark sludge. When there is nothing left, you can cement out the silver by using copper or the silver chloride method, then you can cement out copper and nickel with iron because they pollute the environment. After that you can throw it somewhere in the landscape 

I think your current rised because the electrolyte filled with metal ions. I do not recognize a much different current when the silver plating is removed.


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## Amature

I found through some research that if you take four cups of sulfuric and 50cc of nitric acid elevated to a temp somewhere around 179 degrees Fahrenheit the silver strips off and no base metal is lost. I have tried this and it works extremely well and it is quick. I will have to find the info again to give you more info but I am stripping all kinds of silver pieces and it does not take long to make a troy ounce of silver using this method.


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## goldsilverpro

Amature said:


> I found through some research that if you take four cups of sulfuric and 50cc of nitric acid elevated to a temp somewhere around 179 degrees Fahrenheit the silver strips off and no base metal is lost. I have tried this and it works extremely well and it is quick. I will have to find the info again to give you more info but I am stripping all kinds of silver pieces and it does not take long to make a troy ounce of silver using this method.



We've discussed that solution many times on the forum. It also works pretty well at room temp (a helluva lot safer), but it is slower, especially on thick deposits. How do you plan on recovering the silver from the solution?


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## Amature

As I said I have already recovered and melted several T oz of silver doing this. I use salt to cement the stuff and then neutralize the whole batch with baking soda. I boil it in distilled water a few times and melt it. No magic just followed the instructions I found. It works. I use a food warmer to heat the acid which is very slow to heat it and does not seem to over temp the stuff. I can not explain all the chemistry I just found the info and used it as it was. I am simply sharing what I found. I have attempted to get silver from stuff before with no success but this worked for me. Here is one of the sites I found information at:
http://www.ehow.com/how_7617322_remove-silver-plating-bath.html
http://www.finishing.com/225/07.shtml


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## Drewbie

Amature said:


> if you take four cups of sulfuric and 50cc of nitric acid...



What strengths?

Regards,


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## Amature

I use Rooto for the Sulfuric acid and I use 70% nitric acid


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## teclu

Amature said:


> As I said I have already recovered and melted several T oz of silver doing this. I use salt to cement the stuff and then neutralize the whole batch with baking soda. I boil it in distilled water a few times and melt it. No magic just followed the instructions I found. It works. I use a food warmer to heat the acid which is very slow to heat it and does not seem to over temp the stuff. I can not explain all the chemistry I just found the info and used it as it was. I am simply sharing what I found. I have attempted to get silver from stuff before with no success but this worked for me. Here is one of the sites I found information at:
> http://www.ehow.com/how_7617322_remove-silver-plating-bath.html
> http://www.finishing.com/225/07.shtml




Hello Amature,
Nice and interesting work! But now, please confirm me if I understood correctly:1000 ml distiled water+950 ml h2so4(93%) + 50 ml hno3(70%)= 2000ml deplating solution+ 80 degrees Celsius. For what amount of silver use this 2 liters?
...and, what kind of salt used for cementing? purity of silver? 
teclu


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## goldsilverpro

teclu said:


> Amature said:
> 
> 
> 
> As I said I have already recovered and melted several T oz of silver doing this. I use salt to cement the stuff and then neutralize the whole batch with baking soda. I boil it in distilled water a few times and melt it. No magic just followed the instructions I found. It works. I use a food warmer to heat the acid which is very slow to heat it and does not seem to over temp the stuff. I can not explain all the chemistry I just found the info and used it as it was. I am simply sharing what I found. I have attempted to get silver from stuff before with no success but this worked for me. Here is one of the sites I found information at:
> http://www.ehow.com/how_7617322_remove-silver-plating-bath.html
> http://www.finishing.com/225/07.shtml
> 
> 
> 
> 
> 
> Hello Amature,
> Nice and interesting work! But now, please confirm me if I understood correctly:1000 ml distiled water+950 ml h2so4(93%) + 50 ml hno3(70%)= 2000ml deplating solution+ 80 degrees Celsius. For what amount of silver use this 2 liters?
> ...and, what kind of salt used for cementing? purity of silver?
> teclu
Click to expand...



Use no water at all. Just 950 ml sulfuric + 50 ml nitric.


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## teclu

goldsilverpro said:


> teclu said:
> 
> 
> 
> 
> 
> Amature said:
> 
> 
> 
> As I said I have already recovered and melted several T oz of silver doing this. I use salt to cement the stuff and then neutralize the whole batch with baking soda. I boil it in distilled water a few times and melt it. No magic just followed the instructions I found. It works. I use a food warmer to heat the acid which is very slow to heat it and does not seem to over temp the stuff. I can not explain all the chemistry I just found the info and used it as it was. I am simply sharing what I found. I have attempted to get silver from stuff before with no success but this worked for me. Here is one of the sites I found information at:
> http://www.ehow.com/how_7617322_remove-silver-plating-bath.html
> http://www.finishing.com/225/07.shtml
> 
> 
> 
> 
> 
> Hello Amature,
> Nice and interesting work! But now, please confirm me if I understood correctly:1000 ml distiled water+950 ml h2so4(93%) + 50 ml hno3(70%)= 2000ml deplating solution+ 80 degrees Celsius. For what amount of silver use this 2 liters?
> ...and, what kind of salt used for cementing? purity of silver?
> teclu
> 
> Click to expand...
> 
> 
> 
> Use no water at all. Just 950 ml sulfuric + 50 ml nitric.
Click to expand...


GSP, thank you sir!
With a liter of this solution, how many grams of silver can I „remove” from plated items? I understand that this combination of acids is good for deplating copper alloys silvered(CuZn, CuNiZn) and pure copper silvered. Right? 
I have about 100 kilo of military conectors(40-50 kilo of silvered pins in this quantity). If i put the soldered pins in this solution(Sn, Pb..), can be a problem for the deplating process? And now same question, how can I recovering the silver from the solution? 
Thanks in advance!
teclu


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## goldsilverpro

I think this is a terrible method, especially for the novice, for several reasons. Here are a few of them.
(1) Hot concentrated sulfuric is extremely dangerous. Just a drop of it can cause a bad burn. The larger the amount, the more dangerous it is. For very thin silver, the solution can be used at room temp, but it is slow. 
(2) One gallon will probably dissolve about 5 oz of silver. This is a one shot deal with no re-use of the solution. You generate a lot of waste for a little bit of silver.
(3) According to this excellent link, it takes 25 pounds of baking soda to neutralize 1 gallon of sulfuric. The neutralization procedure is extremely dangerous, especially if the acid is not considerably diluted (and, cooled) first. And, if you do dilute first, the dilution procedure itself is also quite dangerous, since it is exothermic and generates a tremendous amount of heat.
http://www.livoniafirefighters.com/docs/Neutralization%20Formulas%20%26%20Quick%20Access%20Charts.pdf
(4) Concentrated sulfuric absorbs water from the air. Once water gets in the solution, it will start dissolving some copper. That's also why the parts have to be bone-dry before putting them in the solution.

I have used this solution many times, but only so I could either re-plate the copper or to determine the silver content. This procedure has been in the plating literature for probably 100 years. Every refiner knows about it, but I doubt, due to the dangers, inefficiency of it, and the fact that it's very cumbersome to work with, that any refiner has ever used it as a silver recovery method, except on a small beaker scale. 

I can't think of a poorer source of refining information than ehow.com.

I'm not trying to insult anyone. I'm just trying to keep everyone safe. I have a lot of experience with this solution and to even consider using it hot for quantities greater than about 1-2 liters is an accident waiting to happen. To think of setting up to run 100K of material through it is inconceivable to me.


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## teclu

goldsilverpro said:


> I think this is a terrible method, especially for the novice, for several reasons. Here are a few of them.
> (1) Hot concentrated sulfuric is extremely dangerous. Just a drop of it can cause a bad burn. The larger the amount, the more dangerous it is. For very thin silver, the solution can be used at room temp, but it is slow.
> (2) One gallon will probably dissolve about 5 oz of silver. This is a one shot deal with no re-use of the solution. You generate a lot of waste for a little bit of silver.
> (3) According to this link, it takes 25 pounds of baking soda to neutralize 1 gallon of sulfuric. The neutralization procedure is extremely dangerous, especially if the acid is not considerably diluted (and, cooled) first. And, if you do dilute first, the dilution procedure itself is also quite dangerous, since it is exothermic and generates a tremendous amount of heat.
> http://www.livoniafirefighters.com/docs/Neutralization%20Formulas%20%26%20Quick%20Access%20Charts.pdf
> (4) Concentrated sulfuric absorbs water from the air. Once water gets in the solution, it will start dissolving some copper. That's also why the parts have to be bone-dry before putting them in the solution.
> 
> I have used this solution many times, but only so I could either re-plate the copper or to determine the silver content. This procedure has been in the plating literature for probably 100 years. Every refiner knows about it, but I doubt, due to the dangers, inefficiency of it, and the fact that it's very cumbersome to work with, that any refiner has ever used it as a silver recovery method, except on a small beaker scale.
> 
> I can't think of a poorer source of refining information than ehow.com.
> 
> I'm not trying to insult anyone. I'm just trying to keep everyone safe. I have a lot of experience with this solution and to even consider using it hot for quantities greater than about 1-2 liters is an accident waiting to happen. To think of setting up to run 100K of material through it is inconceivable to me.



It is eloquent and to the point! For me everything is clear now, thank you again GSP, sir!
teclu


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## Irons

Never use this formula in a deplating cell, especially with Glycerine. It's a quick way to end your refining career. 8)


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## Martijn

I have experimented with deplating silver with a gold stripping cell method (learned here on GFR ofcourse)  a glass cup with 96% sulphuric acid and a lead anode. I'm so very thankfull for this great hobby you all tought me! Really great advise and lots to read here on the forum. 4.8kilo of plated pins gave me 13 grams gold so far. Made my wife a hand hammered 22K rolling ring. 
Anyway... back to the silver experiment:
The silver starts to drop off around 6 Volt. My power supply has a current regulation and i had it
set it to 2 Amps. After a layer of the silver is deplated, the current slowly drops to almost zero. It get's covered with, i assume, silver sulphate? 
Turning the voltage up to 12 or 15 volts gives another current burst. I did that several times up to 38 volts, at that point there were small sparks visible on the remaining silver. Dont want to have lightning in a cup of pure sulphuric, so 30 volt was my limit from now on... This was a test with a relais contact of 2mm thick layer of solid silver. The lower voltage and current works fine, but is much slower after the current drops. The higher voltage heats up the cell very fast. To keep it in balance, i set it to a 1amp limit and max. 20 volt. No cooling bath or anything making it more dangerous. 
I dont think the current drops because of silver going in solution and altering the cell's performane in
Anyway. Every new piece silver plated copper reacts the same as the first one that went into clean acid.
Havent started getting the silver out yet. I want to collect a bit more to experiment with. After a couple of days the silver settles to the bottom and the acid is clear again. Should be easy to siphon off, dilute and rinse. 
It has been fun to do but i highly doubt if it is profitable unless you're doing it on a large scale or deplating to clean and re-plate items on a regular basis. 

I left some deplated gold pins that had leftover spots of gold on it laying in dilute sulphuric acid. After a while there were gold foils floating around. I think the underlaying metal is eaten away under the gold plate, loosening it, but leaving the copper or brass untouched. The plated layer has to be damaged or at least scratched for this to work. 
Maybe this also works with silver plated copper. That would be less dangerous, leaving the pure acid out of the process.
Well, i have some more experiments to do.


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## rickbb

Since this was first posted in 2011 several members report success with using plain tap water to de-plate silver.


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## Martijn

Thanks a lot. I've been reading an eight pages long post about processing silverplating. It was a long read :shock: but tried it and now i am testing with different plated items. Always lots to learn here.


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