Best Ball Mill Media for Plated Silver Removal

[Fever]

Steve-

The abraded items come out of the ball mill displaying their typical base metal colors. There are Brass and Copper items, some Steel, as well as lots of Zinc items. In the case of vintage plated silverware, I believe many of these are alloys of Zinc and other non-ferrous metals that make for a good "white" base metal upon which the Silver is plated. I've also noticed that many of the Copper and Brass stuff is first plated with Zinc, then followed with a final Silver plate. That way, the Silver is being applied to a "white" metal surface, upon which thinner plating can be achieved while maintaining an economic luster. Just a guess. It may also be to inhibit corrosion or oxidation of the base metals. I will only tumble these Zinc plated items until the Silver layer has been removed. No sense in continuing to abrade additional volumes of Zinc and other base metals. It's quite easy to determine visually when you have exhausted the Silver plate layers and have only the Zinc plating remaining.

-Fever

 

[nickvc]

Fever I'm pleased this working out as we have had many people try to recover silver from plated wares and failed due to the cost. Well done!
I'm not 100% sure but I doubt that the white metal under the plating is zinc but more likely a nickel alloy ( German Silver ) , I'm sure GSP can give a definitive answer to that, he is after all our resident plating expert.

 

[Harold_V]

I'm inclined to agree with you, Nick. I know nickel is the barrier of choice when plating pins and other electrical items. The presence of the nickel barrier prevents migration of the plating to the base metal.

Yeah, I know, that sounds strange, but the phenomenon is well documented and has been known to exist with silver and gold for years. I believe Sir T.K. Rose discussed the issue in his book.

Harold

 

[ORCB]

Hi, I'm interested in physical processes to remove the silverplate, just as a thought experiment. I was reading some threads on here and GoldSilverPro said that it's basically impossible to do economically? How cheap can you get silverplate? If it's only a few cents of silver per square inch, could it ever be worth it, even if you could extract it for zero cost? I don't see how but I have very little experience in all of this.

 

[Fever]

Thanks for the comments everyone!

As stated, Nickel, or an alloy of Nickel, is probably what we're looking at under the plating of most items. It makes sense.

As far as my costs associated with this process? First we must answer this question- What is an acceptable cost for allowing one to quench his/her thirst for precious metals recovery knowledge? I buy all of my plated Silver scrap from thrift stores and garage sales at rock bottom prices. Now, realistically, am I getting back in Silver values what I put into this process in dollars? Most likely not! But, this is something I enjoy doing, it relaxes me after a long day's toil, and that is priceless in itself. I do know one thing; this process seems to be working very well for me, and I believe I am recovering all of the Silver values on these plated items, in whatever amounts they will yield. It will be interesting to see how much pure Silver can be recovered after the digestion/precipitation chemistry is complete (I haven't begun this step yet). All I know is that it's working, I enjoy it, and the process is sound.

I'll keep you all posted as things progress....

Fever

 

[Sodbuster]

If you have a ball mill, make your own grinding media out of some of your old ceramic processors.
As GSP stated "I would try to find a media that was sharp, irregular (to get in all the cracks and crevices), hard, heavy, and impervious to nitric"
Just a thought
Ray

 

[nickvc]

Hi Fever just bumping this thread to see if you have any further updates on your progress?
If you could get starting weights of the plated articles and the final recovered silver it would at least give the members a good idea as to how practical this method is.
I know for you this is about learning but this sounds the best idea so far to recover silver from plated material and who knows you might just have found the method that works.

 

[Fever]

So far, so good. I have been tumbling my plated items in about 3 pound batches, with about 10 pounds of abrasive media as a charge in the ball mill. The reason I don't tumble larger quantities isn't because of the limits of my ball mill (which can happily tumble up to 35 pounds of materials in any given batch), but because I have sheared many of the larger plated dishes and serving platters into strips that will fit through the 4-1/2" mouth of the tumbler. Because of the geometries of these items, they can group together like sheets while tumbling, reducing the exposed surface areas. I am experimenting with bending some of these materials into particular shapes that tend to stay more independent of each other, such as semi-circles. I'm happy with what's coming out of the mill upon completion of the tumbling cycle to this point. There is very little of the abrasive media (Aluminum Oxide "Duramedia XC") being fragmented during the process, and my yield of the fine metal powders and the obvious removal of all surface Silver indicates that I am reclaiming all of the plating on the target items. I am still accumulating the Silver in a glass vessel, and I anticipate doing the chemistry and mechanical separations soon. I have been slammed at work lately, so I'm not able to move forward as fast as I would have liked to. As you can see in the picture, there is roughly 2" of recovered metal particulate sludge in the bottom of my 5" diameter glass vessel. So I have retrieved a 2" X 5" disc-shaped quantity of material from roughly 15 pounds of Silver plated items. I do not tumble the items past the initial removal of the plating, so I am confident that the recovered metals are primarily Silver, with little base metal percentiles (again, to be determined after dissolving, filtering and cementing).

 

[Lonnie]

It's been quite sometime since any post were updated on this process . I have half a coffee jar I tumbled off with a rock tumbler . Removing the silver was the easy part .

I wasn't smart enough to get a medium that wouldn't mix in with the silver/copper I was tumbling . As a result I have a mess LOL . I can place just a pinch in a test tube and add very weak acid solution and I get a fizzing uproar . Better have a bottle to dump the test tube contints into handy .

I did reciently try a pinch in the AP solution and it's showing promise . The home made nitric will not work because the reaction is to foamy . It just climbs out of the test tube . This was a weak solution also . If anyone ever got to the point of melting silver tumbled off I'd like to see something posted concerning the results .

When I done this I figured I could just torch the stuff with copper and silver melting and my medium floating . That didn't quite work as planned and the medium gets hot and starts popping and splattering . I did see small silver balls melting and then running down through the rest of the stuff LOL . However you can't keep a torch on it long enough to melt it all because of the popping and splattering it will do .

If you do try this dont use rock polishing types of grit LOL

 

[FrugalEE]

Lonnie,

I enjoyed your story.

Did you try using water and gold panning like technique to separate the silver?

What is your rock tumbing material? Hopefully something a lot lighter than silver.

I'm doing small experiments recovering silver from mica caps and I'm finding out how sticky cemented silver is. Even getting it off brand new glass beaker is hard and it wants to dissappear into coffee filters.

FrugalEE

 

[Drewbie]

Try experimenting with froth flotation.

 

[Lonnie]

FrugalEE

No I have never tried that . To be honest I was just going to tumble it off and worry about getting it back when I had it all in a jar . Well as luck would have it I was in an accident where I recieved some serious burns so the stuff just set for a couple years . I just reciently cleaned out my tumbler I had going at the time .

The panning might just work I did take about an inch of material and placed it in another coffee jar . Filled it to the brim with water and shook it good and set it down . It did seperate into 3 defined layers .
I could be wrong but I think silvers on the bottom then copper and then my polishing grit. I've been meaning to take a spoon or something and carfully removing a layer at a time and try the torch again to see how it went .

I think I'll give that a try here in a little bit .

Lonnie

btw best of luck with what your trying also . I'm new to this myself so I understand how it can be trying to figure things out .

These caps you mention do they have much silver in them ?? Reason I'm asking is I have a truck load of big electrical caps like the electric company uses . They full of oil and have layers of a silver looking foil seperated by what looks like thin sheets of plastic plus this mica stuff you mention .

Thats where I get most of my interesting material I'd like to get identified . Government auctions and usually big electrical items full of copper ( I scrap for a living ) . I've saved lots of interesting material over the years and it's time to start trying to figure out what some of it is .


btw I have no idea what the medium was . Just some gray looking material made to polish rocks . I tried it with no grit but was getting no where . Adding the grit made it fast LOL a mess but a fast mess :shock:

 

[Lonnie]

Drewbie

Try experimenting with froth flotation


I just tried searching for this froth flotation and as usual I get ( No suitable matches were found.) as a responce . Is their anything else I can search for ?? Thanks for the lead anyhow I'll google it if I have to and look into that .

Thanks to you both for your suggestions .

Lonnie

 

[Drewbie]

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

http://www.chem.mtu.edu/chem_eng/faculty/kawatra/Flotation_Fundamentals.pdf

Enjoy.

 

[FrugalEE]

Lonnie,

Some of those oil filled capacitors contain PCB oils which are considered today as a pretty bad health risk, but you probably already know that and probably can tell which ones contain PCBs and which don't. I don't think any of them contain anything of value and most people consider them a liability. The scrap yard I sell to is pretty careful not to get stuck with any of them or flourescant ballasts, either of which might contain PCBs. The foil you see is most likely just aluminum. I've never taken one apart, but I've certainly used them over the years and continue to keep a supply on hand.

Search the forum for the still active Silver Mica thread and you can get any idea how much silver they contain and how to get it out.

I've seen a lot of different capacitor types over the years and most have no salvage value, the exceptions being mica, chip ceramics, or tantulum types. If you have something you want identified post a photo or describe it in a new capacitor thread and I or someone else will help you figure out what it is.

FrugalEE

 

[Ian_B]

are you guys using water in the tumblers as well as your medium?

 

[Fever]

are you guys using water in the tumblers as well as your medium?

YES

 

[Lonnie]

Ian_B

Yes I did plus a drop or two of dawn dish detergent sure helps keep the black grimy stuff cut loose .


FrugalEE

I couldn't tell a PCB to save my life LOL but they tested now days and are suppost to be using a oil that doesn't contain pcb 's . The big caps I have state on the sides of them the test date and results . I guess that depends on how much we trust the test to be accurate . I do appreachate the warning dude !! Truth is I probably glow in the dark as long as I've scrapped big electrical stuff .

On the tumbled silver I have been getting some good results with the water seperation . I think I have most of the top layer now seperated . I had it at my house and been staying here at moms helping take care of my father . Long depressing story but he's on a vent machine . Thats one reason for the renewed interest in this stuff . I have to have something to take my mind off reality and playing with this has been a life saver for me .

Back to the silver though when I went and got it the stuff got stirred up during the move . So i shook it up good and noticed two layers sunk fast leaving a real fine light brown stuff floating for some time . I suctioned this off and have 95% of this layer in a seperate jar 8) What ever this layer is it's now pure . Funny thing is I figured the grit would be on top but acording to the color it's not the grit . I'm now assuming the light brown / tan layer on top is my copper and my grit is the next layer . Thats just a new guess though and we know how that go's LOL

The other two are just about identical in color but you can see a difference in the layers . I'm to a point where I have to let things settle so I can get them back into a couple jars . Kinda funny how one jar can turn into a dozen when I get to playin with them LOL .

 

[Goldfinger4]

Most plated cutlery is made of a Cu-Ni-Zn alloy. 12% Ni, 24% Zn and 64% Cu is the common alloy for that in Germany.
As Harold said, the white plating under the silver is Ni.
Be careful with dissolved nickel ions, when having contact with your skin it can cause an irritation or even a nickel allergy.
I run my electrolysis until I do not see much white anymore because I think it is difficult to differentiate between corroded silver and nickel.

 

[Fever]

I agree Goldfinger4,

It is sometimes difficult to determine whether you have corroded (or eroded, in my case) entirely through the Silver layer. But, I believe once you condition your eyes to the subtle differences, it can be done to acceptable accuracy. I have my tumbling times down to the point where I know I am abrading and removing the entire Silver plate layers. There will be small amounts of base metals in my sludges, but they should not pose a problem chemically. I have never heard of Nickel allergies- very interesting!

Fever