400 LBS of newer silver plated flatware question

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drpepper843

New member
Joined
Sep 17, 2020
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3
Hello guys,

Drpepper843 here. New to the forum. Happy to be here. Have followed recycling of precious metals for a long time but have never dove in. Well, until recently. I just purchased a pallet of silver plate flatware (Mainly forks) from a local auction. They are all newer made in France and were for a formal dining hall at the Wynn casino. I was told they were silver plate but I'm not certain. Some are new in the box and show tarnish. Other people have the same flatware listed on eBay selling as silver plate. So I just assume they are.

My main question is, If I buy a gallon of nitric acid, is it viable to assume I could possibly be able to strip all the silver and use copper to recover the dust, melt it down and make a descent amount of silver?

The metal seems to be slightly magnetic but the magnet barely sticks. So I assume its a type of stainless under the silver plate.

Any input will be greatly appreciated. Thanks in advance

I'd attached a few pictures but I don't know how
 
If it truly is Ag over stainless then yes, nitric acid will remove the silver and leave the stainless behind as passivated metal.


Having done stuff like this in the past, many tens of thousands of pounds, what I would do is set up a stripping bath in nitric, a stainless basket, then a DI rinsing bath, then another DI rinsing bath, then stack them on a perforated plate to drain.

The main bath will produce NOx and should be vented. The main bath will also get depleted and can be regenerated by adding c. HCl in small quantities to precipitate out the Ag as AgCl and regenerate more nitric acid per the following equation:

AgNO3 + HCl = AgCl + HNO3

To do that "trick" you should really learn how to do a quick Volhard titration (take a look on the forum search, very good post by 4metals).
 
Would have to high end flatware to use stainless as the base metal.

I use a lot of old flat ware in making scrap metal sculptures almost all I've touched is a white/pot metal base. Which is also barely magnetic.

Only way to know is to cut them open and put a drop of nitric on them and watch for any reaction.
 
Thank you guys for the input. I was thinking about a 100 piece test to see how much I'm able to recover. I've just never done it before so I'm a little reluctant. I've watched several videos from streetips and it seems relatively straight forward. Anybody based in Las Vegas that might want to make a day of it? Ill provide the beer lol
 
How long will it take the Nitric Acid to remove the Silver from Silver Plated Flatware?
 
The problem with plated flatware is the base metal under the silver as the nitric will dissolve them in preference to the silver and may well cement out any silver in solution.
 
nickvc said:
The problem with plated flatware is the base metal under the silver as the nitric will dissolve them in preference to the silver and may well cement out any silver in solution.

I agree - nitric I a VERY poor way to try to de-plate silver - once the nitric breaks though "some" of the plating the nitric is going to go to work "more" on the base metal & less on the silver - therefor you are going to use up a LOT of nitric dissolving base metal before the silver is completely de-plated & you may not even get all the silver to de-plate from nooks & crannies

Cyanide would be a far better option

Kurt
 
With the cost of nitric and the price of silver recovering silver from plated material is normally a losing proposition, you can strip the plate using hot sulphuric with a small amount of nitric but that for me is already a big no no, the amount of silver you can recover hardly seems worth the effort in my opinion unless you are doing very large amounts.
 
I just started on my plated French silverware in the H2O stripping cel, and found out from a site that my Christofle plated ware is plated silver on an alloy.
From the site: "The metal that Christofle uses for silverplating is called “maillechort” in French or nickel silver " an alloy of nickel, zinc and copper
https://www.google.nl/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&cad=rja&uact=8&ved=2ahUKEwijqIGNvofuAhXuQEEAHfVhDLkQFjACegQIAxAC&url=https%3A%2F%2Fwww.smpub.com%2Fubb%2FForum7%2FHTML%2F000788.html&usg=AOvVaw215fx_6Sx3m452_UilNucB

So i don't think it's stainless underneath. it's also hard to see when the silver is done deplating, and when nickel or zinc start to deplate.. will have to test my brown gray mud for those metals.
Very careful with nickel compounds > carcinogenic.

I have done one knife, and the knife itself seems to be stainless, no effect to the sharp end in the H2O cel @ 30 Volts. The handle is plated.

Martijn.
20210101_140224.jpg

Fork.jpg
 
To add: this process is very very very slow and took me three evenings to strip 15 items like spoons (flattened in the vice) and forks. Will test later if most silver is off or there is still some remaining. Again, very hard to see.
A brass base would be a lot easier.

As long as I am in the shed stripping PCB's, it's ok to run and keep an eye on, not having to wait between the turns or changes.
400LBS is a no go for me with this process :shock: I have 10 kg of plated stuff.

And since there is nickel the mud from this process has to be refined even further, cutting on the "profit" of your silver…
Don't know if these levels (...tbd) of nickel and zinc cause problems in the Silver nitrate cell.

Ebay may be a faster way to make some money, or sell it to a scrap dealer, they won't even bother giving you a price for silver, may even charge you some for it..

Martijn.
 
I am going to stick with Sterling Silver. The H2O Cell you need a lot of Silver Plated stuff because what I did I got less then 2 grams and it took 2 days to do.
 
I got curious after your results so i went and recovered some mud. Here are my first results after two days of stripping: 6 grams of silver from 8 large spoons and 6 forks and two smaller other plated pieces.
I ass.u.me its pretty pure... 95%+...

I dissolved the brown mud (+/- 30ml, while wet) in distilled water on a hotplate at 60 C and adding small amounts of nitric. 10 ml 50% in total.
Some gray/pink dust would not dissolve. Will test later what that is.
Next time i will rinse the mud filter with some very dilute warm nitric, the silver dust dissolves very fast. No brown fumes noticed.

There is still some silver left in the cementing beaker and some turned into silver chloride after dumping some rinse water in a beaker with a little tapwater left in it.
I've put that in the AgCl pot. Some more nice white cheddar formed. I think i recovered 90% of the silver from this mud into the nugget.

I'm going to give the sripped items a second run to see if anything is left. I have a feeling there is.

Here are some pic's:
20210106_233716.jpg
Little 6 gram nugget with a clumsy borax dimple from the crucible.

20210106_232413_mfnr.jpg
The (partially?) Stripped spoons and forks.

20210106_232403.jpg
Some silver still cementing

Martijn.
 
Martijn, thanks for sharing your results. Do you happen to have a starting weight for the flatware you processed? Results will always vary depending on manufacturer, type of item, age, wear, etc., but any data is good data.

Dave
 
No nitrogen oxides because what you're dissolving is already done being oxidized to Ag(I)...it's Ag2O.

You can likely mix the powder with borax and a small amount of nitre and probably be at pure Ag. Hard to tell with Ni though.
 
The deplated flatware weighs 1.341 kilo.
The dark spoon was bent and used as a cathode after being deplated to have it pointing toward the anode hafway up the beaker.

20210107_144135.jpg
@lou: thanks, now I know its relatively safe to rinse the filter straight with warm dilute HNO3 to get the silver out. Saves on transfers. No need to scrub NO. But it still needs to be done in my fume hood!
Will have to get the ratio of nitric / mud right so some silver will be left undissolved and no free nitric is left when cementing.
And not knowing what nickel and zinc do in this process i went for dissolving and cementing. Don't want any nickel in my dirty silver crucible.
Looking at this amount and weight i think the lot weighs more than 10kg. I guesstimated that while standing on the scale and subtracting my own weight..

Martijn.
 
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