Processing Sterling Silver without nitric acid

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lazersteve

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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:

silver_bowl_25_2oz.jpg



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):

silver_bowl_progress.jpg


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
 
Kev,

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

Ag_Cell.jpg



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.

twice_ag.jpg


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. :D

More to come...

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

thanks

Jim
 
Nitric acid has no effect on graphite.

But it will degrade slowly while in use because of the bubbles abrasion.
 
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
 
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
 
lazersteve said:
Kev,

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

Ag_Cell.jpg



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.

twice_ag.jpg


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. :D

More to come...

Steve
 
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?
 
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
 
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
 
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
 
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 :?: :?:

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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