# Processing Sterling Silver without nitric acid



## lazersteve

All,

I wanted to share the progress of my recent ventures into refining some sterling silver that I had purchased.

The item I experimented on was an old solid sterling silver bowl that I acquired from a lady who had inherited it from her mothers collection. Here's how the bowl looked the day I purchased it last week:








The bowl weighed 25.2 oz (713 g). I cut the bowl into pieces and melted it down into a bar slightly smaller than a US dollar bill and almost 1/4" thick. 

I processed the sterling bar using electricity (12V 10A battery charger) and and electrolyte of left over copper nitrate from previous inquartations and cementing reactions(see on my website). 

I initially used a copper mesh cathode (negative lead) and when the copper level dropped, I switched to a hard graphite block (2" x 4" x 1/2"). With both cathodes the copper built up as a heavy moss on the cathode and was periodically scraped into a Tupperware dish for further cleaning. As the copper levels dropped silver was co-deposited with the copper onto the cathode. The silver tends to accumulate on the back side of the cathode and the copper on the front.

The solution became more and more saturated with silver nitrate as the experiment went on. Here's is a photo of the partially dissolved anode (left), the cleaned silver powder (center), and a 52.2 gram test melt of the resulting purified silver (bottom left) with a U.S. quarter for size reference(bottom right):






As you can see the purified silver is much finer than the original piece and the anode bar. The surface of the silver button is crabby indicating good purity. The button will now be run through a Thum cell to remove the last traces of impurities.

I plan on posting a video of this process when time permits. As you can see, the bar still has some ways to go before it is completely processed. The bar in the photo has been in the cell for 10 hours. I ran the cell for 2 hours per day for the last five days to get to this point.

More to come...

Steve


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## Noxx

Interesting !

Keep us posted !


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## usaman65

Steve-

Can you post pics of the cell?

thanks
kev


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## lazersteve

Kev,

Here's a photo of the cell when not in use, and without the electrolyte.







and here's some of the twice refined silver that I recently pulled out of the cell. The refined silver is in the form of small crystals and shines like diamonds in the sun. It's so pure I refuse to melt it as I know melting it will take away from it's beauty.






I'll post a shot of the cell in action the next time I load it up.

The container is just a 1 gallon square plastic pitcher, the cathode is a piece of hard graphite, and the anode is a silver bar. The anode and cathode are held in place by the plastic cabinet child locks shown in the photo.

On the silvers first pass through the cell the anode was as shown in the opening photo (a melted sterling silver bowl). The electrolyte was a batch of spent nitric acid that had been cemented using copper. The result of this first pass is the loose powder in the opening photo. 

The bulk of the copper was removed from the electrolyte prior to collecting any silver at the cathode in the first run. The collected silver powder was washed in HCl to remove any copper contamination before remelting. Once melted you get the the large button of silver in the first post. This button (and several like it) are then melted into 4" x 1" anodes and wrapped in a porous filter cloth. These wrapped anodes formed the positive connection in the second run.

The second run I used the exact same electrolyte as the first run, except this time the copper levels were so low (in the electrolyte and the anodes) that the silver formed the crystals seen in the above photo.The crystals were scraped off of the graphite cathode (I used a fresh cathode for the second run) every 10-30 minutes. I used a smaller pyrex dish for the cell on the second pass.

By adding HCl to the boiled down electrolyte from the second run, I obtained fresh nitric acid and silver chloride. The nitric is then reused for inquarting (or whatever you want) and the entire process repeats.

As an added bonus the HCl washes of the first stage silver powder form CuCl2 which can be used to process fingers.  

More to come...

Steve


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## usaman65

O.k. 

So you have the sterling "dirty" silver on the positive, copper nitrate solution, copper "mesh" negative. Can you use Just a pure copper electrode rather than mesh?



------so I assume that since there is a copper in the solution, some of the copper is removed from the bar as well as all out of the solution when in operation.-----




Is their any color differance between the copper powder and the silver powder on the front/back of the graphite cathode?



what is the importance of the cloth on the silver anode in the second run?


Wolnt the copper/silver just plate out on the copper cathode in the first run rather than accumulate as powder?



----Im seriously interested in this meathod so just a couple Q's-----

thanks
kev


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## lazersteve

usaman65 said:


> So you have the sterling "dirty" silver on the positive, copper nitrate solution, copper "mesh" negative. Can you use Just a pure copper electrode rather than mesh?
> 
> ------so I assume that since there is a copper in the solution, some of the copper is removed from the bar as well as all out of the solution when in operation.-----


The inital step involes converting the copper nitrate into nitirc acid. This is accomplished with two graphite electrodes, or a graphite positive and a copper mesh negative. The mesh provides more surfaces to extract the copper moss on and tends to allow the moss to adhere better to the negative electrode when the negative needs to be scraped. 

When the color of copper that is forming at the negative electrode darkens the positive electrode can be swapped out to the sterling anode. The drawback to using copper for the negative in this inital step that when the power is switched off the plated copper moss will begin redissolving in the electrolyte. also any moss that falls off of the negative will redissolve in the electrolyte. *No silver is involved at this stage.*

Some copper is still in the electrolyte after this step and will plate out as a red moss.



usaman65 said:


> Is their any color differance between the copper powder and the silver powder on the front/back of the graphite cathode?



Yes. The copper moss is red and the silver moss is a whitish gray. The copper converts to silver if it sluffs off of the negative electrode. I let mine grow a very large mass of moss before scraping. This tends to build up more silver with each scraping.



usaman65 said:


> what is the importance of the cloth on the silver anode in the second run?


 It captures any debris, gold, or other PGMs, that may be in the dissolved silver. If omitted the debris or other sludge will end up mixed in with your purified crystals. It allows you to easily pull these other solids out.


usaman65 said:


> Won't the copper/silver just plate out on the copper cathode in the first run rather than accumulate as powder?


The graphite cathode grows a copper/silver moss in the first sterling run. This copper/silver moss is drained and scraped off periodicaly into a separate dish. I use a strainer ladel under the negative electrode when fishing out the mosses. Any copper moss that falls into the electrolyte quickly converts to silver via cementation. For this reason *don't use a copper cathode at this stage*. If the initial setup is performed properly the copper levels are so low, you only get minor amounts of copper moss to large amounts of silver moss in this run (about 7-10%). The copper moss easily dissolves in HCl and is then separated from the silver moss which is then melted with a soda ash flux into new anodes for the second run.


usaman65 said:


> ----Im seriously interested in this meathod so just a couple Q's-----



Great, it's always nice to get feedback on my experiments!


Steve


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## Anonymous

Steve your making nitric with electrolysis, cool. Question, does the nitric react with the graphite anode?

thanks

Jim


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## Noxx

Nitric acid has no effect on graphite.

But it will degrade slowly while in use because of the bubbles abrasion.


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## Anonymous

Are you freaking kidding me? that would be great, man, I never even tried because of strong oxidizer & carbon make things that usually go boppp real loud.

thanks

Jim


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## usaman65

Steve-

Im in the process of buying required materials for this project now. Ill let you know if i have any success with your process.

kev


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## Palladium

8)


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## lazersteve

lazersteve said:


> Kev,
> 
> Here's a photo of the cell when not in use, and without the electrolyte.
> 
> 
> 
> 
> 
> 
> 
> and here's some of the twice refined silver that I recently pulled out of the cell. The refined silver is in the form of small crystals and shines like diamonds in the sun. It's so pure I refuse to melt it as I know melting it will take away from it's beauty.
> 
> 
> 
> 
> 
> 
> I'll post a shot of the cell in action the next time I load it up.
> 
> The container is just a 1 gallon square plastic pitcher, the cathode is a piece of hard graphite, and the anode is a silver bar. The anode and cathode are held in place by the plastic cabinet child locks shown in the photo.
> 
> On the silvers first pass through the cell the anode was as shown in the opening photo (a melted sterling silver bowl). The electrolyte was a batch of spent nitric acid that had been cemented using copper. The result of this first pass is the loose powder in the opening photo.
> 
> The bulk of the copper was removed from the electrolyte prior to collecting any silver at the cathode in the first run. The collected silver powder was washed in HCl to remove any copper contamination before remelting. Once melted you get the the large button of silver in the first post. This button (and several like it) are then melted into 4" x 1" anodes and wrapped in a fibrous filter cloth. These wrapped anodes formed the positive connection in the second run.
> 
> The second run I used the exact same electrolyte as the first run, except this time the copper levels were so low (in the electrolyte and the anodes) that the silver formed the crystals seen in the above photo.The crystals were scraped off of the graphite cathode (I used a fresh cathode for the second run) every 10-30 minutes. I used a smaller Pyrex dish for the cell on the second pass.
> 
> By adding HCl to the boiled down electrolyte from the second run, I obtained fresh nitric acid and silver chloride. The nitric is then reused for inquarting (or whatever you want) and the entire process repeats.
> 
> As an added bonus the HCl washes of the first stage silver powder form CuCl2 which can be used to process fingers.
> 
> More to come...
> 
> Steve


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## qst42know

Reads much better with the photos re-installed. Thanks Steve.

If starting with dehydrated copper nitrate how would you be sure to end at the right concentration to run a silver cell. Does this achieve a balance by it's self?


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## lazersteve

The patent states (Click Here)to start with 6 Molar or less copper nitrate solution to make the nitric. I don't recall the lower limit, but you'll see the solution turn nearly clear with a slight blue tint. You'll also notice a faint smell of NOx.

The copper will continue to deposit down to the lower limit of the reaction as long as the voltage is applied. Be sure you have removed the copper moss and the cathode before you turn off the power on the first go around.

On the second go around, you can tell when the solution becomes too saturated with copper again, by the color change back to darker blue and the color of the silver moss that is formed.

Once this happens, repeat the first process to regenerate your nitric acid.

Steve


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## goldenchild

This is definately another video opp for you Steve. I have a few bars of silver saved up myself using nitric. I was wondering how you guys go about getting silver to quad nines? What I did(and I think it worked is) I took the dissolved silver from gold processing and persipitated it out with a copper bar. I then gave it a few good washes with water and then dissolved it again. I again persipitated it out of the now much cleaner silver solution and washed thouroughly. At this point after I dry it out it looks like the 99.99 bag below that Steve refuses to melt. I then finally take this and boil it in HCL to get rid of any remaining copper followed by several rinses. Is this an ok method to do this? Also how do you test silver for 99.99. I have the little red acid bottle but that only tests for 925. Is there a similar test for 99.99?

Thanks all for you input


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## HAuCl4

Nice thread and process. Where can those graphite blocks/electrodes be obtained?.


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## aflacglobal

8)


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## please35

Dear Lazersteve

Thanks for your teach.

I need ultrafine WHITE silver powder for illuminating.

I did almost the same except graphite which I dont have and dont know where to buy.I used steel.

When there is silver curd .I take out and wash many times with plain water.Then I boil with HCL.

Its been 3 week I am trying and didnot found.
My result so far:
when I make silver curd.its clay color.fine but not ultra fine.I clean and boil with HCL but color didnot changed.But when I rub the sponge on porcelian bowl.the side which I rub on wall is shining like diamond as you said but not all the partical is shining.

1, How to make ultra fine.
2.how to make all dust silver particle bright as diamond as you mentioned.
3.did you put on heat to make shining ?

Please kindly help me I am in trouble. 
rgds


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## shyknee

please35.
Can you explain what this means.


> *I need ultrafine WHITE silver powder for illuminating.*


I am at a loss when you refer to illuminating :?: :?:


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## please35

shyknee said:


> please35.
> Can you explain what this means.
> 
> 
> 
> *I need ultrafine WHITE silver powder for illuminating.*
> 
> 
> 
> I am at a loss when you refer to illuminating :?: :?:
Click to expand...


shyknee.

it mean I have to put around the photo frame.so photo frame will be 24 K silver frame.To attract the customer silver powder MUST be white sparkling as lazersteve had mentioned like diamonds and must be very fine.When you disolve this you cannot feel the grit of silver.Hope I mae it clear.If you can please help me.
robin


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## goldsilverpro

please35 said:


> shyknee said:
> 
> 
> 
> please35.
> Can you explain what this means.
> 
> 
> 
> *I need ultrafine WHITE silver powder for illuminating.*
> 
> 
> 
> I am at a loss when you refer to illuminating :?: :?:
> 
> Click to expand...
> 
> 
> shyknee.
> 
> it mean I have to put around the photo frame.so photo frame will be 24 K silver frame.To attract the customer silver powder MUST be white sparkling as lazersteve had mentioned like diamonds and must be very fine.When you disolve this you cannot feel the grit of silver.Hope I mae it clear.If you can please help me.
> robin
Click to expand...


I would think you surely can buy silver powder for illuminating from a gold leaf dealer. Or, could you buy silver leaf and crumble it? What about silver cell crystal ground or chopped (blender with water or some solvent?) very fine?

BTW, there is no such thing as 24K silver. Karat only applies to gold.


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## please35

goldsilverpro said:


> please35 said:
> 
> 
> 
> 
> 
> shyknee said:
> 
> 
> 
> please35.
> Can you explain what this means.
> 
> 
> 
> *I need ultrafine WHITE silver powder for illuminating.*
> 
> 
> 
> I am at a loss when you refer to illuminating :?: :?:
> 
> Click to expand...
> 
> 
> shyknee.
> 
> it mean I have to put around the photo frame.so photo frame will be 24 K silver frame.To attract the customer silver powder MUST be white sparkling as lazersteve had mentioned like diamonds and must be very fine.When you disolve this you cannot feel the grit of silver.Hope I mae it clear.If you can please help me.
> robin
> 
> Click to expand...
> 
> 
> I would think you surely can buy silver powder for illuminating from a gold leaf dealer. Or, could you buy silver leaf and crumble it? What about silver cell crystal ground or chopped (blender with water or some solvent?) very fine?
> 
> 
> BTW, there is no such thing as 24K silver. Karat only applies to gold.
Click to expand...


I wish to d it my self so pls suggest me any thread/rgds
robin


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## shyknee

What is the material of the frame ? Is it copper or brass ? you just want to make it look like silver plate wright ?


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## please35

shyknee said:


> What is the material of the frame ? Is it copper or brass ? you just want to make it look like silver plate wright ?




its wood I'll paste silver with gum
rgds
robin


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## shyknee

You need silver leaf to glue to the wood .
No powder will ever stay shyknee for a long time,
I be-leave you have a plan, whether you can implement it or not is still a mystery .
when you discover what you want to do and do it. I would be interested in taking a peek a your project . 
Good Luck


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## infinatesorrow

question on the copper and graphite anode, say you had a large copper bar with a thick plate of silver over it, that should work as well as the graphite rod and shorten the process? well maybe not too long since ive thought about electrical theory lets see 3 things are required a cathode , an anode and an electrolyte/ acid of some kind to initiate the movement of electrons. but............. now the graphite rods we use to air arc have a coating of cant remember on them ill have to look at them when i go to work tomorrow but it may also help to expedite the process


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## element47

Steve, I assume you sawed up the bowl and ended up with sort of triangular pieces sort of like the petals of a flower. Is there any particular reason why you didn't just use the sawn-up bowl pieces as individual anodes? Yes of course you would have had to replace them periodically, certainly more often than just using the brick you melted the bowl into. I'm just curious as to why you went to the extra step of melting the pieces into a single ingot.


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## lazersteve

element47 said:


> Steve, I assume you sawed up the bowl and ended up with sort of triangular pieces sort of like the petals of a flower. Is there any particular reason why you didn't just use the sawn-up bowl pieces as individual anodes? Yes of course you would have had to replace them periodically, certainly more often than just using the brick you melted the bowl into. I'm just curious as to why you went to the extra step of melting the pieces into a single ingot.



So that I could set up the cell with the single anode and let it run. Other than that no particular reason.

Steve


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## jawed

DEAR SIRS 



I am seeking an accurate and detailed definition for the process
of recovering silver from processed X-Ray films.
To get you started I post a nice fee and I will contribute another tip
if the answer comes quick enough.
I intend to purchase a refining machine from CPAC, So you can assume
it is in possession. Also assume very large quantities of Film.
What I have learned so far:
There are two possible processes which interest me, first one is to
run a bleach-fix solution through film and process the solution.
Second option is to lay the film in a bleach solution and then wash it
with water and run it through a fixer solution which is then
desilvered.
What I am trying to do is come up with accurate cost for the entire
process (you don't need to refer to transportation of the film). From
you I don't need the costs of machines and materials, but I do need an
exact chemicals list and machines involved in the process as well as
structures (like a bath for the film to sit in).
Please fill in the details for the two alternatives given above.
Good luck and happy research.


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## goldsilverpro

jawed,

Everything you need to know about processing film has been written on this forum. Search! Look especially for articles on the subject by goldsilverpro, Juan Manuel Arcos Frank, or sena. There are others but much of what you want is by these 3 authors.

I know that if I were to help you, I would be the one to establish the consulting fee, not you.


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## eesakiwi

Would it work to electroplate the refined silver directly onto the picture frame?


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## ilikePM

Hi folks. I have a few questions regarding this technique. First thing I would like to know is it possible to use clean unused 70% Nitric acid and dilute it with RO water to say 50/50 %, and use this as the electrolyte? I would like to simply cut a piece of sterling silver, wrap it with some fine cloth (to absorb slimes) and use it as an anode, then use a stainless steel bowl for the cathode. I have a digital battery charger that allows me to dial in exactly what I need, in this case 3v DC at 1-10 amps (or higher). Will this setup work to grow some nice pure silver crystals? Does the electrolyte have to have an initial silver and copper nitrate dissolved in it for this to work properly? 

Eventually when the electrolyte gets saturated with copper nitrate, I would implement Laser Steve's technique of growing copper out of the solution. Essentially I would like to bypass dissolving silver in pure nitric acid, and then cementing with copper, then making an anode with the cemented silver. I would like to use voltage and current to force silver to dissolve in a dilute nitric acid electrolyte. Nitric acid is very expensive, and I would like a system where I can recycle the nitric acid for as long as I can. At the moment I have around a half gallon of 70% nitric acid, and I need to plan how to use it wisely.


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## freechemist

@ilikePM,

You ask:

"_I have a few questions regarding this technique. First thing I would like to know is it possible to use clean unused 70% Nitric acid and dilute it with RO water to say 50/50 %, and use this as the electrolyte?_"

Definitely not. This nitric acid would be much too concentrated. It serves only to dissolve metallic silver (without electrical current), to prepare a concentrated silver nitrate solution, serving as a base for a silver-electrolyte used in a silver cell. Such an electrolyte contains (average-values) about 100-200 g Ag per liter and ca. 6 g HNO3 per liter. A much higher free HNO3-concentration leads to redissolution of silver-metal deposited at the cathode.


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## MysticColby

another problem: in the copper cell described to produce copper + nitric from copper nitrate, wouldn't any silver deposit before the copper?


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## ilikePM

Ok, so the nitric acid must be very diluted then. Can anyone recommend a water to nitric solution? Would 10% nitric acid and the rest water work? From what I understand a week acid solution will be influenced by current to deposit crystals on the other end of the circuit. The key here is a delicate balance between acid concentration and current. I am guessing this balance should equalize on it's own after running the cell for a while.


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## goldsilverpro

ilikePM said:


> Ok, so the nitric acid must be very diluted then. Can anyone recommend a water to nitric solution? Would 10% nitric acid and the rest water work? From what I understand a week acid solution will be influenced by current to deposit crystals on the other end of the circuit. The key here is a delicate balance between acid concentration and current. I am guessing this balance should equalize on it's own after running the cell for a while.


The "key" you're missing is the silver concentration in the solution. Just nitric and water won't work. You must start with dissolved silver in the solution to the tune of about 60 to 80g/liter. You can use sterling silver for this. The 7.5%-9% copper in the sterling won't hurt and will actually help produce better crystal. You dissolve the silver in a minimum amount of nitric acid diluted 50/50 with distilled water. If you dissolve the silver in an open top container, it takes about 1.22 ml of nitric plus 1.22ml of distilled water to dissolve a gram of pure silver and about 1.5ml of nitric plus water to dissolve a gram of sterling. If you do this right, you'll probably end up with about 1 or 2% free nitric in it which is OK. For each liter of solution, I would use about 2 - 3 amps. One amp will produce about 3 to 4 grams of silver crystal per hour.


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## ilikePM

Ok sounds good. I have 19 grams of sterling silver I will test with. Does the electrolyte even need nitric acid in it? In other words the silver and copper that are in the solution are all that is necessary to conduct the current to the cathode.


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## goldsilverpro

ilikePM said:


> Ok sounds good. I have 19 grams of sterling silver I will test with. Does the electrolyte even need nitric acid in it? In other words the silver and copper that are in the solution are all that is necessary to conduct the current to the cathode.


19 grams isn't much. You could only make about a 300-400ml cell from that and that would be stretching things. I have no idea how you're going to cram all the needed things into a cell that small. Also, if you're trying to run sterling through it, the silver dissolved in the solution will be depleted to the point in about a day, or less, so that the copper will start contaminating the crystal. Also, the distance from anode to cathode will be so small that you'll have to remove the crystal about every hour to prevent the electrodes from shorting. I would wait until you have enough silver to make a bigger cell. 

Usually I don't worry about the acid. I assume the nitric you're using is at least 67%. Dissolve the 19 grams in about 30 ml of nitric plus an equal amount of distilled water. If it doesn't all dissolve, heat it a bit. If it still doesn't dissolve, add 2 or 3ml more nitric. Do all this in an open top beaker so all the fumes escape. For this amount, I would use at least a 200-250ml beaker so it doesn't foam over. Let it cool and filter the solution to remove any dirt. Dilute it to the working volume with distilled water.


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## ilikePM

Yea I realize that 19 grams is nothing, but I have a few ounces of sterling to work with. Since this is my first time doing this I don't want to mess up on a big batch, and I would like to test the process before I go larger. I saw on the youtubes someone who built a very tiny silver cell in a small cup, and that gave me the idea to do this small batch. If I mess up somewhere it wont be a big deal, but if I mess up on a few ounces I would be pretty upset. Thank you for your help!


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## ilikePM

Hey GSP. I found this post from you that answers my question earlier regarding using straight sterling. It makes a lot of sense.

"In the 80s/90s, when I had my last refinery, I had one 30gal silver cell operating most of the time. I'm not big on sleeping with silver cells so I usually ran it about 12 hours.day. I probably averaged about 1000 oz/week, mainly from sterling, big contact points, and x-ray film. Most of my silver was cast into 10 and 100 oz bars and sold at a premium. When I first started the refinery, I ran the sterling straight through the cell. Replenishing the cell every couple of days got old fast. I soon switched over to dissolving the sterling and the points and cementing the silver out with copper.

The 2 processes are sort of, six of one, half dozen of another - same amount of acid, same amount of dissolving. In practice, though, semi-purifying the silver before putting it in the cell takes a lot less labor, when all is told, and it is easier."


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## goldsilverpro

ilikePM said:


> Hey GSP. I found this post from you that answers my question earlier regarding using straight sterling. It makes a lot of sense.
> 
> "In the 80s/90s, when I had my last refinery, I had one 30gal silver cell operating most of the time. I'm not big on sleeping with silver cells so I usually ran it about 12 hours.day. I probably averaged about 1000 oz/week, mainly from sterling, big contact points, and x-ray film. Most of my silver was cast into 10 and 100 oz bars and sold at a premium. When I first started the refinery, I ran the sterling straight through the cell. Replenishing the cell every couple of days got old fast. I soon switched over to dissolving the sterling and the points and cementing the silver out with copper.
> 
> The 2 processes are sort of, six of one, half dozen of another - same amount of acid, same amount of dissolving. In practice, though, semi-purifying the silver before putting it in the cell takes a lot less labor, when all is told, and it is easier."


One quick comment. That sort of gives the impression that I initially melted the large contact points and ran them directly through the cell. For safety reasons, I never melted them due to the cadmium content that is most always present in points. I always dissolved them and cemented the silver out.

I must admit that, once, when I was young and foolish and had my first-ever batch of points, I did melt them. There were bright red toxic cadmium cobwebs everywhere - in the furnace, on the tongs and mold, and tons floating around in in the air. Never again did I do that. Screw-ups are often the best teachers.


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## ilikePM

Has anyone considered installing a low value fuse on their silver cells? This way you have some protection just in case of a short when you are not looking.


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## FrugalRefiner

A common suggestion is to include a small light bulb in the circuit (like a car tail light bulb). The brightness of the bulb gives some indication of the current flowing through the circuit, and it also serves to limit the current.

Dave


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## ilikePM

Thats a cool idea!


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## mikeinkaty

goldsilverpro said:


> ilikePM said:
> 
> 
> 
> Ok, so the nitric acid must be very diluted then. Can anyone recommend a water to nitric solution? Would 10% nitric acid and the rest water work? From what I understand a week acid solution will be influenced by current to deposit crystals on the other end of the circuit. The key here is a delicate balance between acid concentration and current. I am guessing this balance should equalize on it's own after running the cell for a while.
> 
> 
> 
> The "key" you're missing is the silver concentration in the solution. Just nitric and water won't work. You must start with dissolved silver in the solution to the tune of about 60 to 80g/liter. You can use sterling silver for this. The 7.5%-9% copper in the sterling won't hurt and will actually help produce better crystal. You dissolve the silver in a minimum amount of nitric acid diluted 50/50 with distilled water. If you dissolve the silver in an open top container, it takes about 1.22 ml of nitric plus 1.22ml of distilled water to dissolve a gram of pure silver and about 1.5ml of nitric plus water to dissolve a gram of sterling. If you do this right, you'll probably end up with about 1 or 2% free nitric in it which is OK. For each liter of solution, I would use about 2 - 3 amps. One amp will produce about 3 to 4 grams of silver crystal per hour.
Click to expand...


GSP - I think I understand the above for making the 'starter' solution. Let's say I make a 1 liter solution by disolving say 70 grams of Sterling in the nitric/h2o. This solution would be silver nitrate with copper in it? Or, would that be a mixture of silver nitrate and copper nitrate? In the next phase, the electrolysis phase, how much silver can I expect to percipitate from Sterling bars before having to make a new starter solution?

From reading below I'm kind of getting the idea that the starter solution can be 'recycled' enumerable times. Is this correct? The title of this thread first led me to believe that nitric acid was not needed - that all you had to do was start the electrolsys in a solution of copper nitrate. So, maybe my question would be - how much silver can you expect with each cycle? I have about 25 Toz's of Sterling that I want to process as cheaply as possible. If the process is to expensive then I'l just melt the sterling down and keep it as sterling bars.
Thanks, 
Mike


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## goldsilverpro

> GSP - I think I understand the above for making the 'starter' solution. Let's say I make a 1 liter solution by disolving say 70 grams of Sterling in the nitric/h2o. This solution would be silver nitrate with copper in it? Or, would that be a mixture of silver nitrate and copper nitrate? In the next phase, the electrolysis phase, how much silver can I expect to percipitate from Sterling bars before having to make a new starter solution?
> 
> From reading below I'm kind of getting the idea that the starter solution can be 'recycled' enumerable times. Is this correct? The title of this thread first led me to believe that nitric acid was not needed - that all you had to do was start the electrolsys in a solution of copper nitrate. So, maybe my question would be - how much silver can you expect with each cycle? I have about 25 Toz's of Sterling that I want to process as cheaply as possible. If the process is to expensive then I'l just melt the sterling down and keep it as sterling bars.
> Thanks,
> Mike


Mike,

I could probably write at least 20 or 30 pages on the silver cell, but that's not going to happen. Instead, I'll just give you some non-technical information about what happens in the cell.

(1) Besides pure water, a basic silver cell contains 3 chemicals: Silver nitrate = AgNO3, Copper Nitrate = Cu(NO3)2, and a little Nitric Acid = HNO3. When in solution, each splits into positive and negative ions (charged species). For these three, you would have these 3 positive ions in solution: H+, Ag+, and Cu+2. The only negative ion in solution would be the nitrate ion, NO3-. All solutions must have an equal number of positive and negative charges. For each H+ or Ag+ ion present, there must be one NO3- ion and, for each Cu+2 ion, you would need *2* NO3- ions. Note that I could have written Cu++, instead of Cu+2 - same thing.

(2) Note that there is a finite number of nitrate ions, NO3-. If the solution is made up properly, with plenty of silver and not too much copper, only silver will deposit at the cathode - no copper. As the silver plates out, it is replaced by silver and copper ions from the sterling anode. However, since each copper ion requires 2 nitrate ions and, since there is only so much nitrate ion available, the silver in solution will decrease. There's more to it than that but, if you do the math, you'll find that, for each gram of copper dissolving at the anode, the amount of silver in solution is reduced by 3.4 grams. That's really all you need to know.

(3) To prevent copper from co-depositing with the silver, the silver concentration in the solution should be kept above about 25g/l and the copper below about 75g/l. There is some variation in this, but that is a good rule to follow. If the copper is low, you might get away with a little less silver

(4) Say you started a one liter solution by dissolving 70g of 90/10 sterling in a minimum amount of nitric acid. The silver concentration would be 63g/l and the copper 7g/l. This cell should work until the silver is reduced to 25g/l or a reduction of 63-25 = 38 grams of silver. To eliminate that much silver from the solution, 38/3.4 = 11.2 grams of copper would have been dissolved from the anode. In other words, this would happen after 11.2/.1 = 112 grams of sterling had been dissolved. Time-wise, if you were running only 1 amp through the cell, this would happen in about 25-30 hours of operation. At that point, you would have to remove part of the solution and replace it with enough silver nitrate solution (silver dissolved in nitric) to build up the silver in the solution to an acceptable level. If you add back fairly pure silver solution, you will also reduce the copper in the cell somewhat. The silver from the waste cell solution is cemented on copper and then dissolved in nitric to make fresh solution. To know how much cell solution to remove and how much silver solution to replace it with requires some slightly heady math. 

(5) The moral of this story is that it's a lot of extra work to run sterling anodes in the cell because you have to constantly mess with it. If you first dissolved that sterling you were going to use as anodes in nitric acid, cemented the silver out with copper and rinsed it well, you would have about 99% silver. If you used the 99% silver as anodes, you would be able to run about 10 times more silver though the cell before you had to mess with the solution. And, whether you ran 90% or 99% silver through the cell, it would end up taking exactly the same amount of nitric acid, when all is said and done.

Chris


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## ilikePM

Hi folks. Here is an update with images from my experiments. I have not been able to grow copper out of the cell. I tried using a copper tube for the cathode while using stainless steel for the anode, and it didn't grow red copper onto the tube. It doesn't really mater since I have been able to grow very pure silver crystals anyways. The title of this topic is misleading since you do need nitric acid in the whole process. I realized this is essentially a silver cell.

I tried using straight sterling for an anode, and as it dissolved the silver did not crystalize onto the cathode, but instead it turned into a grey powder ( just like LS's test ). So far I have been reusing the electrolyte solution and it seems to be holding up. I had processed some sterling in nitric acid, and simply poured the solution without cementing into the cell and nice silver crystals grew on the cathode. I also made some cemented silver anodes and replaced them as they dissolved in the cell. I did notice that eventually the electrolyte does tap out, and I can tell when it happens because crystals stop growing, and the solution becomes a crystal clear blue solution. Also the smell of nitric acid goes away, and it's hard for a new anode to dissolve in the solution. So I simply added some new ( silver cemented out ) copper nitrate solution into the cell, with a fresh new anode, and the process picked right back up again. Sometimes you can actually see the silver in solution as very tiny little specks of silver reflect light off of them. When you cant see them anymore it's about time to replenish the solution.

I am using a stainless steal spatula that I removed the wooden handle and bent into shape. It provides a lot of surface area for silver to grow off of. I put a 10 amp fuse on the cathode just in case of a short since I leave it on 24/7. The circuit pulls around 4 amps at 3v with a PC power supply. I am using a plastic bottle for an anode slime trap, and it seems to be working well. It also shields the anode from any potential short.


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## qst42know

> I am using a plastic bottle for an anode slime trap, and it seems to be working well.



Are you using any filter cloth with this bottle or just the holes?


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## goldsilverpro

Gotta have a filter cloth.


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## ilikePM

yes I got to put one in there. I noticed a darker spot on the lower corner of the cathode. I will have to remove that part and refine it again. What is this dark powder that remains after dissolving the anode? Copper, silver? Is it worth saving?


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## mikeinkaty

I have an old Stainless Steel ice cream freezer can that is about 6" diameter and 12" tall. Would that work? I know with electrolysis that the distance from anode to cathode and the ion concentration determines how much current will flow. From all the pics i've seen here, 2" or 3" inches must be about the right distance to use for SIlver? I use to de-rust large cast iron tools with electrolysis and I would crank the amperage up to 20 amps and let er go. I have large 20 amp variacs and can vary the voltage. The cast iron and the solution would get boiling hot. But it removed the rust very quick. From what I read here, people have said that 3 volts is apparently the ideal voltage for a silver cell. But, I suspect the thing one really needs to control is the current. What is the ideal current in a silver cell? My variacs have a volt meter and an amp meter on the output circuit.

If I can use the ice cream can then how to suspend the silver inside is the next question. Maybe I could pour the silver into long rods? Or, what if I suspended a bar at the top of the solution then inserted a plastic sleeve around the inside of the can for about the first 3"?? That might keep silver crystals from growing out to the bag containing the bar. But, would the plastic add contamination to the silver?

Then my next question is how to connect the electric wire to the anode? I have some non-lead silver solder that I bought from Ace Hardware about 20 years ago and plenty of flux. Any reason that would not work? I could keep the connection point out of the solution.

How many crystals, by weight, could I grow before having to clean them out and recharge the solution with such a setup?

Mike


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## WillGreen

This is amazing!
My silver never looks like this - I am referring to the picture of LazerSteve with the silver in the silver bag. 
I apologise for my complete ignorance, but is it possible to refine gold using electricity? 

Best regards,

Will


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## anands138

amazing post!

i saw a company on the internet selling a Electrolytic Gold Refining Plant. 

is it possible to refine gold via electrolysis? or are these some sort of scams?


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## g_axelsson

Yes, you can refine gold in an electrolytic cell, called the Wohlwill process.

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

Not as common for the small refiner as there is a lot of gold locked up in the electrolyte.

Göran


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## ilikesilver

Hey steve, i have a question, i thought sterling silver is pure silver, if it is, why go through this process to purify it more?

Tim


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## jimdoc

ilikesilver said:


> Hey steve, i have a question, i thought sterling silver is pure silver, if it is, why go through this process to purify it more?
> 
> Tim




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


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## ilikesilver

ty for the responce


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## ilikesilver

i must have read this post 8 to 9 times, one thing i dont understand is that if your removing copper into the solution and growing your crystals using .925 silver / starting with, why couldnt you use less quality silver like .800? would the copper saturate the liquid to much?

tim


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## FrugalRefiner

ilikesilver said:


> i must have read this post 8 to 9 times, one thing i dont understand is that if your removing copper into the solution and growing your crystals using .925 silver / starting with, why couldnt you use less quality silver like .800? would the copper saturate the liquid to much?
> 
> tim



The less pure your feedstock, the faster your electrolyte will be contaminated. This can result in contamination of your silver crystals if you run too much. You can run lower quality feedstock, but you have to replace your electrolyte more frequently.

Dave


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## nickvc

Dave you can mess with the electrolyte by adding more nitric to dissolve more silver and so decrease the copper concentration, it works for a while and I'm sure it could for a long time if you had the right testing equipment, one of my friends apparently has been running his large cells on the same electrolyte for months running mixed silver quality bars but monitoring the acidity of the solution, don't ask me thats over my comprehension :shock:


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## FrugalRefiner

Thanks Nick! I have some experiments in mind along these lines. As I get results I'll be posting them here.

Dave


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## ilikesilver

hey guys, what if you were to take and melt the low quality silvers with a higher quality silver to get it at the level you need say towards .925 using variations of different qualitys. then couldnt you use that up. a lot of times lower quality silver comes free, were the higher stuff you have to buy or trade for. just a thought tim


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## maynman1751

> The inital step involes converting the copper nitrate into nitirc acid. This is accomplished with two graphite electrodes, or a graphite positive and a copper mesh negative. The mesh provides more surfaces to extract the copper moss on and tends to allow the moss to adhere better to the negative electrode when the negative needs to be scraped.
> 
> When the color of copper that is forming at the negative electrode darkens the positive electrode can be swapped out to the sterling anode. The drawback to using copper for the negative in this inital step that when the power is switched off the plated copper moss will begin redissolving in the electrolyte. also any moss that falls off of the negative will redissolve in the electrolyte. No silver is involved at this stage.
> 
> Some copper is still in the electrolyte after this step and will plate out as a red moss.



To recover/remove the copper from the silver nitrate solution could you use two stainless electrodes?


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## butcher

You need an anode, which is inert to the nitric acid electrolyte.
Stainless at the anode would be oxidizing into solution at the anode; the graphite is inert, although it may break down a bit from the gas bubbles.


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## maynman1751

Thanks Richard! 8)


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## butcher

Some types of stainless steel (normally the types with higher chromium content, and non magnetic) will not dissolve into concentrated nitric acid, the stainless steel passivates in the highly oxidizing environment of the concentrated nitric acid.
Type 304 or 316 stainless will passivate in concentrated nitric acid, 304 types would be preferred over 316 for storage of concentrated nitric acid.

Dilute nitric will attack many metals easier than the concentrated nitric acid (stainless steel is no exception here) although it will still not dissolve as easily a many of the other metals will.

When we use electrolysis with a metal as our anode we can force a metal to dissolve into solution (the electrolyte) as ions. The power supply is forcing the electrons to move in the atoms of these metals that may not normally be oxidized in the same solution if it was not used as an electrolyte (or as the anode). Even a metal that would not normally dissolve in this same solution, if this solution was used as just an acid, and not as an electrolyte, or in an electrolytically process.

Besides the power supply forcing electrons to move in the electrolytic process, we also have the anode forming scrubbing bubbles: which can also help to remove an oxidized layer (or passivated layer of salts if it forms.

I am not sure if I explained this very well or not.


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## the iron dwarf

I am new here and have a quantity of silver to process sometime in the future.
I have been reading random threads here and am working my way through Hoke's book, then will re read both threads and the book making notes before I consider doing anything.

I have been thinking of dissolving silver in nitric and cementing it out and when needed removing the copper with the process above to make my nitric usable again and reduce the waste I have to deal with.

I have a few of the electrodes from arc air which I think are graphite with a thin copper coating and could probably get some large motor brushes which I also think are graphite, are either of these suitable or should I just buy some graphite rod or block to use for the cell to convert copper nitrate to nitric


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## butcher

The copper coated air arc cutting rods are small in diameter, the thin layer of copper will also go into solution as the anode giving you a longer time to remove copper from the copper nitrate solution, I also believe the graphite in them is soft and fairly porous.

Most motor brushes are fairly dense graphite, some motor brushes will also contain a metal depending on the brush type, and some have the graphite around a braided copper lead wire, which if it went into solution would give the electrolyte added copper, for very small lots a large graphite motor brush may work.

All in all I would look into buying large blocks of graphite, it can be cut into sheets for your cell projects, and to make molds out of, you also can find it reasonably priced.


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## the iron dwarf

thank you butcher


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## covoner

Good job. I will like to see that video.


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## spikeyharold

Hi Guys
Ive been reading through as many posts as I can and Hokes book. Im looking at refining a small amount of sterling silver to create some 999 silver electrodes (for silver plating). Being in the UK getting Nitric is a little difficult, but getting copper nitrate doesnt appear to be too hard. SO.. Reading the initial experiment, would I be correct in surmising , I could use a 40% copper nitrate (shop bought) solution as my starting liquid. A copper cathode (followed by a graphite cathode) and the sterling as the anode. And I would end up with silver (in need of further refining) and a Nitric Acid solution suitable for further processing more silver? Which would be the perfect solution for me or have I missed something? 
Thanks
Steve


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## FrugalRefiner

You're sort of on the right track. Starting with copper nitrate, you can use electricity to reduce some of the copper, depositing it as metal at the cathode, leaving free nitrate ions (NO3-) in solution. But that same electric current will also oxidize the sterling silver you plan to use as the anode. The silver and copper will go into solution. As this happens, you'll start to have both silver and copper depositing at the cathode.

Now if you used a graphite anode and either a copper or graphite cathode, the copper would again be reduced and deposited at the cathode. But since graphite doesn't go into solution, you will start to develop some weak nitric acid. There will probably be a limit that will keep you from pushing all the copper out, so you can achieve a mixture of nitric acid and copper nitrate.

You could then use that solution to dissolve some of your sterling. Then you could cement the silver out by putting in some metallic copper. You would end up with cemented, metallic silver and copper nitrate solution. You could conceivably repeat this process over again and again, but the solution would eventually become contaminated and need to be processed as waste.

The silver cement you produce won't be the 999 you're wanting. To achieve that, you'd want to set up a silver cell. Start with a fresh copper nitrate solution and create some nitric solution as before. Dissolve some of the silver cement into it and you'll have your electrolyte. Melt the rest of the cement and either pour it into an ingot or shot it to use as your anode. You'll find all the details on silver cells here on the forum.

I've often considered running this exact process as an experiment to test the limits of the system, but I just haven't had the time yet. It all works in theory. Since I haven't done it, I can't tell you if you'll run into any problems. Since there is no free H+ in the solution, it would have to come from the water. That may or may not cause problems.

It's a lot of work, but it might provide an alternative for those who can't buy nitric.

Dave


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## resabed01

Tonight I tried recovering the copper/nitric acid from a waste solution of copper nitrate I had left over from some inquartaion I did a while ago.
I used a copper coated arc rod as Butcher mentioned. If you do it right, you can peel the copper off the rod in a sheet and have both your anode and cathode. I ran the cell for about an hour as a trial and it worked well. Not sure what voltage to run this cell, I ended up using the +5v bus from a old computer power supply. Just from the hour or so I ran the cell I could see several grams of copper removed from the solution and no noticeable erosion of the graphite rod.

Tomorrow I will set it up and let it run all night.


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## snoman701

You might look in to carbon arc electrodes. Traditionally these are just copper plated graphite. 

Obviously this was posted earlier by Butcher. To make this post worthwhile since I can't delete it....

I have read through the forum in relation to selective refining via voltage variation. It is my understanding that at higher voltages, you have a greater chance of copper deposition, whereas at the lower voltage the nitrate only reacts with the silver atoms.

With that, there was at least one patent which placed a third electrode in the solution, close to the anode, as you can then measure the voltage drop over the solution, as well as the voltage drop right at the transition. This effectively reduces the variation in cell design, but would also allow one to set up a simple PID controller to vary power supply output to match the potential needed to only drop silver. Has anyone on the board played around with such a beast?


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## Rougemillenial

lazersteve said:


> All,
> 
> I wanted to share the progress of my recent ventures into refining some sterling silver that I had purchased.
> 
> The item I experimented on was an old solid sterling silver bowl that I acquired from a lady who had inherited it from her mothers collection. Here's how the bowl looked the day I purchased it last week:
> 
> 
> The bowl weighed 25.2 oz (713 g). I cut the bowl into pieces and melted it down into a bar slightly smaller than a US dollar bill and almost 1/4" thick.
> 
> I processed the sterling bar using electricity (12V 10A battery charger) and and electrolyte of left over copper nitrate from previous inquartations and cementing reactions(see on my website).
> 
> I initially used a copper mesh cathode (negative lead) and when the copper level dropped, I switched to a hard graphite block (2" x 4" x 1/2"). With both cathodes the copper built up as a heavy moss on the cathode and was periodically scraped into a Tupperware dish for further cleaning. As the copper levels dropped silver was co-deposited with the copper onto the cathode. The silver tends to accumulate on the back side of the cathode and the copper on the front.
> 
> The solution became more and more saturated with silver nitrate as the experiment went on. Here's is a photo of the partially dissolved anode (left), the cleaned silver powder (center), and a 52.2 gram test melt of the resulting purified silver (bottom left) with a U.S. quarter for size reference(bottom right):
> 
> 
> As you can see the purified silver is much finer than the original piece and the anode bar. The surface of the silver button is crabby indicating good purity. The button will now be run through a Thum cell to remove the last traces of impurities.
> 
> I plan on posting a video of this process when time permits. As you can see, the bar still has some ways to go before it is completely processed. The bar in the photo has been in the cell for 10 hours. I ran the cell for 2 hours per day for the last five days to get to this point.
> 
> More to come...
> 
> Steve


I’m quite impressed with this one. Nice work. Would it be possible to take the CuCl2 waste leftover and convert it back to hydrochloric acid by use of sulfuric acid and then electrolyze as Nurdrage did to recycle spent copper chloride PCB etching solution. That way it’s pretty much full circle. All the copper is recovered and separated from the silver.


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## Rougemillenial

spikeyharold said:


> Hi Guys
> Ive been reading through as many posts as I can and Hokes book. Im looking at refining a small amount of sterling silver to create some 999 silver electrodes (for silver plating). Being in the UK getting Nitric is a little difficult, but getting copper nitrate doesnt appear to be too hard. SO.. Reading the initial experiment, would I be correct in surmising , I could use a 40% copper nitrate (shop bought) solution as my starting liquid. A copper cathode (followed by a graphite cathode) and the sterling as the anode. And I would end up with silver (in need of further refining) and a Nitric Acid solution suitable for further processing more silver? Which would be the perfect solution for me or have I missed something?
> Thanks
> Steve


how did you get Cu nitrate? The only way I could do this is via arc reaction of air to make nitric.


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## lazersteve

Copper nitrate is easily produced without nitric acid via basic high school level chemistry. No electricity is required for the production of Copper Nitrate, except maybe to produce some heat to evaporate off the excess water.

Steve


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## lazersteve

ilikePM said:


> ... The title of this topic is misleading since you do need nitric acid in the whole process. ...



Nothing could be further from the truth. Copper nitrate production doesn't necessarily require nitric acid.

Steve


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## g_axelsson

lazersteve said:


> Copper nitrate is easily produced without nitric acid via basic high school level chemistry. No electricity is required for the production of Copper Nitrate, except maybe to produce some heat to evaporate off the excess water.
> 
> Steve



How?

Göran


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## lazersteve

Take note: You saw this here first as it relates to refining.

Any nitrate plus copper sulfate comes immediately to mind. The nitrate ion can be exchanged almost indefinitely with proper process control. It's only when you start producing BFRC (Big Freakin Red Cloud) that you are losing the power of the nitric acid. There will always be some losses, minimizing these is key to recycling the nitrate.

Nitrates are typically more soluble than sulfates, so simple evaporation followed by cooling leaves the nitrate after pouring/filtering off the cold nitrate solution from the sulfate crystal. 

This has the added benefits of virtually no nitric fumes and recyclable in the case of copper sulfate. Copper sulfate is a super useful reagent. It can be converted to sulfuric acid using electricity and evaporation.

Nitrate salts are cheap and ship most anywhere. You can even leach nitrates right out of most any top soil.

I have an entire process related to this "closed loop" production of in situ "nitric". For most hobbyists refining purposes there is no need to isolate the nitric acid at all. Instead all you need is a nitrate source, copper sulfate, muriatic acid, and some electricity occassionally. Of course as with many of the hobby work arounds, an investment of time is required at a few of the stages of these processes.

Proper nitric acid is expensive, hazardous, and not required. It is still a good idea to distill a liter or so of good 68% nitric acid to have on hand. Any of my work around nitric formulations (including this one) can be used as a source for this distillation process to obtain your 68% nitric acid.

Steve


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## nickton

So what's the basic high school chemistry for producing copper nitrate?

Sorry in advance for being so dumb. :mrgreen:

I think I'LL LOOK IT UP.


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## ION 47

snoman701 said:


> You might look in to carbon arc electrodes. Traditionally these are just copper plated graphite.
> 
> Obviously this was posted earlier by Butcher. To make this post worthwhile since I can't delete it....
> 
> I have read through the forum in relation to selective refining via voltage variation. It is my understanding that at higher voltages, you have a greater chance of copper deposition, whereas at the lower voltage the nitrate only reacts with the silver atoms.
> 
> With that, there was at least one patent which placed a third electrode in the solution, close to the anode, as you can then measure the voltage drop over the solution, as well as the voltage drop right at the transition. This effectively reduces the variation in cell design, but would also allow one to set up a simple PID controller to vary power supply output to match the potential needed to only drop silver. Has anyone on the board played around with such a beast?



The device is called a "potentiostat". I use it to process photographic solutions and extract silver. when little silver remains in solution, it is impossible to ensure the selectivity of the deposition.


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