# Silver Mica Capacitors



## lazersteve

Here's a fairly common component that contains silver in the plates of the rectangular section as shown on the right side of the photo below:







These are known as silver mica capacitors and are typically found in older TV and radio equipment and in surplus shops by the thousand. They are easy to identify by their burgundy colored purple soft epoxy shell as seen on the left side of the photo above.

You can easily remove the epoxy with a few hammer blows (or a ball mill) to free the legs and the silver rectangles as seen in the center of the photo above. The legs are mounted via two crimps on either end of the rectangular plates.

The silver plates are each separated by a thin layer of mica to form the desired value of capacitor using the proper spacing, number, length, and width of plates.

Typical yields for these types of capacitors is 1 troy ounce of silver per pound of components. Larger value capacitors will produce more silver as they require larger surface area plates. The silver can be melted directly as 999 silver without further processing if you are careful not to include any of the crimps or legs in with the harvested rectangles. The mica will melt around 900C just before the silver does @ 962C.

The legs are not silver and should not be included in the silver you harvest. 

Steve


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## bigjohn

Thanks for the info! Yet another thing to keep a eye out for.


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## glondor

Nice Find. Thanks for sharing. I will keep my eye out for those.


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## escrap

I knew those 7 boxes of monitor boards were sitting around the shop for something..lol We shall see if it is worth our time. Thanks for the good info as always.


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## FrugalEE

I have lots of those and many are much larger. I've posted below another type of silver mica typically found in transmitter RF circuits. Look to the left where they are flat on board, but there are also some on end. This guy is usually well soldered as the whole purpose of this type is to reduce stray lead length for better efficiency and bandwidth. The trimmer capacitor on right with the big slot head screw is also mica and may have silver in it.

I'm wondering if those old disc ceramics like the one in upper right of trimmer have any values. I've used unpotted versionswhere they soldered down to a board and used as a terminal to locate lead(s). Those seemed to have silver. 

I have vintage micas in attic, but those are probably best EBAYed and I think most are unsilvered micas.

FrugalEE


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## lazersteve

I went out and melted a 100 of the rectangles with soda ash flux and came up with a silver colored bead that skinned over purple when cool. Looks like the best route to the silver may be to use either flotation to separate the lighter mica layers from the silver foil layers or to use 35% HNO3 to go straight for the silver.

I used a MAPP torch for the test and it took 30 minutes to get everything molten even with the flux. Maybe my furnace would have been a better choice. The mica was very resistant to the heat by itself, but once the flux was added the mica melted quickly and the tiny silver BBs began to collect together. Under the torch flame the silver was nice and bright colored.

I tested the foils with Schwerter's before melting and got a nice bright red that did not fade, so I'm sure I was dealing with the silver variety. I believe the flux may have liberated some other metal from the mica which combined with the silver.

I'll do some more testing tomorrow as I have several pounds of these.

Steve


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## FrugalEE

Thanks Steve,

I take it your parts are new and free from solder. I would not have expected mica to melt. I'm thinking I may have seen you post on doing those caps, but a search on mica got nothing. Since I get HNO3 cheap I will probably try that approach at least for first sample. I should be able to find some clean parts to play with.

FrugalEE


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## Harold_V

FrugalEE said:


> I would not have expected mica to melt.


It is most likely being dissolved, which is a function of the proper flux when melting non-metallic substances.

The resulting metal from those caps, once collected by melting, would be excellent for inquartation, assuming it contains no lead. That way processing can be considered free, assuming one has need for silver for inquartation. 

Harold


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## Irons

FrugalEE said:


> I have lots of those and many are much larger. I've posted below another type of silver mica typically found in transmitter RF circuits. Look to the left where they are flat on board, but there are also some on end. This guy is usually well soldered as the whole purpose of this type is to reduce stray lead length for better efficiency and bandwidth. The trimmer capacitor on right with the big slot head screw is also mica and may have silver in it.
> 
> I'm wondering if those old disc ceramics like the one in upper right of trimmer have any values. I've used unpotted versionswhere they soldered down to a board and used as a terminal to locate lead(s). Those seemed to have silver.
> 
> I have vintage micas in attic, but those are probably best EBAYed and I think most are unsilvered micas.
> 
> FrugalEE



Good point about Ebay. HAM Radio operators and their ilk like to use them because their low thermal coefficient and their high voltage rating. They're pretty expensive retail, if you can find the values you need.


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## lunker

FrugalEE,

I have pounds of the flat capacitors you showed in the pics, When I took them apart I was testing the peices and the small square peices inside seem to indicate Palladium. I havn't tested with DMG to give me a positive result. but I used harolds test of heat, and they came out a pinky purple rainbow colour. I then read in an old dental metallurgy book that an alcoholic solution of potassium iodide will leave a black stain on palladium. When I checked it with this it left a black stain that could not be rubbed off.Any possibility you could test yours and see if you get similar results? I will need to source some DMG.


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## FrugalEE

Lunker,

Good to hear you're exploring this part and I'm impressed with your testing. You're way ahead of me. I was hoping to put a couple of the caps in some nitric today, but the wife wanted to shop for drapes. As I think more about it I'm afraid the high copper content will just cement out the silver and I'll get a mess. I'll probably have to add HCl to get Ag to drop as a chloride. Need to study more or get some guideance. I have a scale capable of .01 gram resolution and small assay types of experiments is what I'm interested in. 

I've got lots of electronic parts that I've been accumulating for 56 years now. I haven't done much building the past few years so I can't always find something real quick, but I did find my assortment of the subject cap. My memory is that I've seen only one vendor for that part. The board I photoed has UNELCO brand (Underwood electric company?). I found my hoard of parts and all 65 of them are also UNELCO. That should reduce the variations of how this type of part is built.

I bought a 10 gram bottle of DMG from Carolina a couple of months ago, but haven't done anything with it yet. PM me your address and I'll mail you some.

FrugalEE


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## Barren Realms 007

FrugalEE said:


> Lunker,
> 
> Good to hear you're exploring this part and I'm impressed with your testing. You're way ahead of me. I was hoping to put a couple of the caps in some nitric today, but the wife wanted to shop for drapes. As I think more about it I'm afraid the high copper content will just cement out the silver and I'll get a mess. I'll probably have to add HCl to get Ag to drop as a chloride. Need to study more or get some guideance. I have a scale capable of .01 gram resolution and small assay types of experiments is what I'm interested in.
> 
> I've got lots of electronic parts that I've been accumulating for 56 years now. I haven't done much building the past few years so I can't always find something real quick, but I did find my assortment of the subject cap. My memory is that I've seen only one vendor for that part. The board I photoed has UNELCO brand (Underwood electric company?). I found my hoard of parts and all 65 of them are also UNELCO. That should reduce the variations of how this type of part is built.
> 
> I bought a 10 gram bottle of DMG from Carolina a couple of months ago, but haven't done anything with it yet. PM me your address and I'll mail you some.
> 
> FrugalEE



Don't add HCL but keep adding nitric in small amounts and the copper will get used up and the silver will go into solution, filter your solution and then use copper to cement out the silver. Then should have clean silver with no trash in it.


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## FrugalEE

Thanks Barren I'll do just that. I hope that works as it will be much easier to dry and weigh metal silver. The ratio of copper to silver is going to be very high, maybe even 100 to 1. I remember years ago dissolving a silver dime in nitric, but there we have 90% Ag with only 10% Cu.


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## Barren Realms 007

It should allow you to filter your solution out and not have to deal with any trash.


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## pinwheel

I just bought a gaylord of these vintage rf boards. Good to know about these mica caps. ;-)


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## Oz

FrugalEE said:


> Thanks Barren I'll do just that. I hope that works as it will be much easier to dry and weigh metal silver. The ratio of copper to silver is going to be very high, maybe even 100 to 1. I remember years ago dissolving a silver dime in nitric, but there we have 90% Ag with only 10% Cu.


Lunker,
I had not heard of alcohol and potassium iodide testing of palladium before. I will have to look into that a bit.

FruugalEE,
Barrens advice to digest in nitric is what I would do, partially because I detest dealing with silver chloride. But in this case it seems likely there will also be some lead. Using HCl added to a nitric solution to remove your silver as a chloride will also give you lead chloride that will co-precipitate if lead is present. You will not have any lead as a solid if you cement to copper. When you go to cement if there is palladium present as well as silver they will both cement on copper, you will notice that Pd is present if your cement is darker than usually seen when just cementing silver on copper. You may wish to repeat your silver dime experiment so you can see how silver cement looks on copper in nitric. Use just enough 50/50 nitric to digest your dime so you are not having to digest alot of copper to get all of your silver cemented.

Since you have DMG, test a small sample after digesting. I would suggest you use a test tube for this since you think your solution will be rather dark with copper. Put a small sample of your solution in your test tube then add a couple of drops of your DMG solution. Agitate it a bit to mix it then let it rest for 10 minutes. The reaction itself is fast, but it can take a bit to settle if the amount of Pd is small. If you do not see a precipitate after this, it would be a good idea to dilute your test with some distilled water to make your solution more transparent. I recommend the distilled water in this case to be sure you do not introduce any chlorides that could give you a sediment of silver or lead chloride that you may mistake as a Pd reaction in a colored solution. You are looking for a light yellow precipitate as a positive for Pd, but its color may be masked by your solution color.

Since you bought DMG I would also suggest you buy or make some Schwerter’s solution for testing silver.


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## FrugalEE

Barren and Oz, 

Thanks again for your replies and they tell me that the dissolving of the metals is an entirely separate operation and the cementing won't happen until I put in fresh metal Cu. One part of my brain was trying to tell me that I would either get a mess of Cu sticking to Ag or that the Ag would go into solution and immediately precip out as metal. Oz, when you say go easy on the HNO3 when dissolving dime it implies to me that Cu added is going to just go into solution until pH drops to a certain point and then we're going to have cementing start to happen. It also implies that weak HNO3 solutions may not dissolve without some cementing happening right away. 

I'm going to start with clean new parts that shouldn't have any solder unless it was used to make the part. I have Schwerter's solution as part of a gold testing kit, but I haven't used it yet. I also have the raw chemical to make more.

I doubt that these micas are still being used very much. They have mostly been replaced by ceramic chip caps. Recovering values from these guys is going to be tough with the solder to deal with. Steve cleverly eliminated the Cu & solder from his melting of the epoxy micas and I'm anxious to take a hammer to some of my old dipped micas. To recover from the UNELCOs we might want to remove the heavy Cu although it is obviously silver plated and there might be more silver on the Cu than on the mica. Anyway, it's an interesting project.

FrugalEE


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## lunker

Oz
I found it in a old student text book on dental metallurgy. It was for distinguishing palladium from platinium.From what I have been able to gather. It dosn't stain stainless, aluminium steel nickel silver. You can buy it at the pharmacy as a antiseptic.If the parts are palladium it could be one more way of narrowing down what a material is or is not.

FrugalEE,
I dissolved some in nitric and cemented them out on copper. I melted the silver powder.I don't know if my mapp torch is weak ir if there is palladium in the mix but i couldn't get it to melt. So I got angry and melted it with a oxy acetylene torch. I know that was a bad move! the resulting bead is covered with pox marks from the gas bubbling out on cooling.Still nor sure if it was just the silver spitting or the palladium spitting.Without the DMG I am running blind!

I would gladly buy some test solution from you. But i live in Ontario Canada.Shipping may be tough.But thank you for the offer!


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## FrugalEE

Lunker,

Good report. What I had in mind was putting something like a half gram of DMG powder in a plastic enveope inside a normal letter envelope and mailing it to you for FREE. I know some people get excited about white powder in envelopes. Would that be a problem for Canada?

I just picked out two 510 Pf parts and weighted them---- 3.318 grams so I need about 18 ml of 50/50 HNO3. 

I would expect the more Pf the part is rated for the more values to be had. I don't recall seeing parts higher than 1000Pf and I found one I had at 12 Pf which seems unusually low for that type of part. I remember these parts as being rather expensive when they first started showing up.

FrugalEE


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## Oz

FrugalEE said:


> I just picked out two 510 Pf parts and weighted them---- 3.318 grams so I need about 18 ml of 50/50 HNO3.


Remember when you do your calculations that you expected a good deal of copper in these parts. It takes 2.38ml of 50/50 nitric to digest a gram of silver, however it takes 8.10ml to digest a gram of copper. In other words it takes 3.4 times more 50/50 nitric to digest copper than it does the same amount of silver.


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## FrugalEE

Thanks Oz, 

I posted it wrong, but I figured on the basis of assuming all the weight was Cu and the number I actually did was close to 28 ml. It's in the 45 degree garage bubbling away. That 3.4 ratio is nice when cementing, but not so nice when dissolving.


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## Oz

FrugalEE said:


> It's in the 45 degree garage bubbling away.


A heated work space huh? I was fighting the cold all last night in the lab as I do not heat it. It was taking about 15-20 minutes before a spray bottle would have the nozzle freeze and I would have to exchange it for a thawed one from in the house.


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## Barren Realms 007

Oz said:


> FrugalEE said:
> 
> 
> 
> It's in the 45 degree garage bubbling away.
> 
> 
> 
> A heated work space huh? I was fighting the cold all last night in the lab as I do not heat it. It was taking about 15-20 minutes before a spray bottle would have the nozzle freeze and I would have to exchange it for a thawed one from in the house.
Click to expand...


Yep I agree with the weather, 14F this morning at 1:00AM. I will have to admit at least you don't have to wait for your solution to cool in an ice bath for filtering..


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## FrugalEE

Oz, 

You have my sympathy. No way could I stand that.
Our south facing basement garage is not heated except for solar and unintentional losses from the house. I've gone out of my way to seal and insulate the heat ducts and I've turned the doors into solar collectors.


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## Irons

Oz said:


> FrugalEE said:
> 
> 
> 
> It's in the 45 degree garage bubbling away.
> 
> 
> 
> A heated work space huh? I was fighting the cold all last night in the lab as I do not heat it. It was taking about 15-20 minutes before a spray bottle would have the nozzle freeze and I would have to exchange it for a thawed one from in the house.
Click to expand...


Good time to make Poor Man's nitric, Methinks. :mrgreen:


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## Barren Realms 007

Irons said:


> Oz said:
> 
> 
> 
> 
> 
> FrugalEE said:
> 
> 
> 
> It's in the 45 degree garage bubbling away.
> 
> 
> 
> A heated work space huh? I was fighting the cold all last night in the lab as I do not heat it. It was taking about 15-20 minutes before a spray bottle would have the nozzle freeze and I would have to exchange it for a thawed one from in the house.
> 
> Click to expand...
> 
> 
> Good time to make Poor Man's nitric, Methinks. :mrgreen:
Click to expand...


Yep does great making it in these temps when it comes to the cooling step but I still put it on ice.


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## lunker

frugalEE,

Would greatly appreciate the DMG, As for customs. I highly doubt there would be any issues. I used to work for a importer who manufactured in China. I cleared customs at pearson Int'l. You could almost reach out and touch the planes as they landed.Security really didn't seem to be a big priority.PM me and I would gladly give you my info.

As for the parts, A friend brought me hundreads of boards that are covered with these things. Also alot of gold parts. said they came from old police radio equipment.Mabey a place to look for scrap?


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## FrugalEE

Lunker,

I mailed your DMG this morning from our post office.

I finally got my two test capacitors dissolved in nitric, but I had to add quite a bit of heat and more water and nitric. It dissolved everything but the mica and a little white powder. After filtering and adding some deionized water I set aside a few ml solution in a test tube and then put a 7.5 gram copper sheet in the beaker. It started cementing right away. After 4 hours it looks about finished, but I'll leave it over night. 

I mixed up some DMG solution, but the best alchohol I could find was some old Vodka at 39%. At least that is better than rubbing alchohol, but the best seems to be HEET in the yellow botttle or something close to 100% grain alchohol. Anyway the 0.25 grams I put into 25 ml is not all dissolved YET.

I put a sample of my filtered solution in a minature test tube and added some DMG. After about 15 minutes I could see a small amount of light yellow precip in the bottom of the tube. 

I put another sample on a plastic spoon and added Stannous test solution. It turned light yellow, I added some more and it got more yellow, but after a few minutes it turned clear and I have white powder which is almost certainly silver chloride.

I put a third sample on a spoon and added some silver test solution I got in a kit. I presume it is Schwerter's, but the bottle is incorrectly labeled as just acid. This one turned yellowish green and gradually got darker. The sheet on the test kit says that silver 65 to 75% will be light green in color and 80 to 90% will be light red or brownish. It takes 90 to 100% to turn dark red. Does anybody know if this kind of test solution is standard Schwerter's or something special designed for jewelery/coin testing??

Tomorrow I'll harvest and dry my precip and weigh it as well as the copper piece.

We're at the start of a heat wave so conditions in the garage were bearable today for a change and I had fun doing this.

FrugalEE


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## FrugalEE

This morning the stannous test sample that was yellowish green and then went clear is again yellowish green and I can't see any precip. That's pretty weird!

The DMG test is the same and there definitely is precip, but it's a stretch to say it's yellow, however it is in a dark blue solution from all the Cu.

I googled this part and the common term for it is clamped mica. I plan to do some unclamping to study the structure. I found a couple of surplus outfits selling them for $1.25 (12Pf) to $3 (470 Pf like I dissolved) each. I also found lots of references to things like Motorola application notes where the part was used in transmitting circuits. It almost got me wanting to build transmitters again.

FrugalEE


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## FrugalEE

Funny thing happened, I removed and cleaned my Cu strip and went to breakfast. When I went to recover my *cementations *about 30 minutes later I found that they had *dissolved* back into solution. I've been searching the forum and found good postings back in Nov of 2008 by Oz, Harold, Lou, and GSP and I've come to the realize I made the following mistakes:
1. I should not have pulled the Cu out before I was ready to pour & filter. Do you seasoned cementers always leave the Cu in just prior or even during the pour off process?
2. I used too much nitric.
3. I didn't dilute enough
4. I didn't agitate and scrape cement off the Cu enough
5. I stopped cementing too soon
6. I created a lop sided solution that has way too much Cu vs values. It's maybe 100:1 and I suspect that creates a considerable overlapping between conditons for dissolving and conditions for cementing. I can help the metal ratio by removing end terninals and dealing with them separately.

Any comments? 

FrugalEE


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## Harold_V

FrugalEE said:


> Any comments?


Only one. 
You used too much nitric. Everything else doesn't matter. You can leave copper in with the recovered (cement) silver as long as you wish, with no real negative effects---so long as you don't have too much nitric present. 

Hoke comments in her book that the novice tends to use too much acid. You can better learn the lesson by heating your reactions, so the acid works rapidly---and it's obvious when it is exhausted. 

There is no need to agitate while cementing (although it certainly does no harm). The only thing that is required is that you agitate when the reaction is near completion, so you uncover silver nitrate that has been dragged down by cemented silver and trapped. Agitation allows the silver nitrate to be included in the solution, where it is then exposed to copper for cementation. 

Harold


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## FrugalEE

Harold, 

Thanks, I did heat, but not very hot and I added too much nitric as it was taking quite awhile. I'm still getting cement out and I'm denoxing right now. Another really funny thing happened. The 1/2 inch or so I set aside in a test tube before diluting and cementing has grown a copper foil like sliver about 3/4 inch long and 1/16 inch wide. What's going on there?

*Results so far:* I recovered .325 grams of Ag/Pd in a coffee filter and I'm going to have to burn this to get anything out. I'll use the filter again for a second filtering of what is left and weigh again.

I took another 510 Pf cap apart quite easily and photographed the pieces in the order removed. The frame clamp (far left) is quite beefy as is the next metal piece. Everything is plated both sides except those weird copper foils. There is quite a bit of wax in the assembly and I should have incinerated before putting parts in nitric. The wax got all over my beaker and was hard to remove.


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## lunker

FrugalEE,

That's what the ones I have look like. I tested the parts with schwerters before I dissloved them and they came up blood red.I have taken 25 square peices and have filed the plating off of them to reduce the amount of copper in solution. I am dissolving the plating in nitric and will add Hcl to precipitate the silver as a chloride. I can then filter the solution and de nox. I will see if any Pd cements out. or could test with DMG. Dose this sound like a correct approach?


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## FrugalEE

Lunker, Do I understand correctly that you took 25 capacitors apart and filed the silver off 4 metal pieces in each? Lot of work, but that will surely get rid of most of the copper and you'll be able to come up with good numbers. It's too bad there isn't a decent way to strip silver plating and recover it economically. What value caps are you dealing with? Lower values will not have so many parts.

Unless you are sure that will separte the two I advise against the chloride approach and just cement in nitric. If Pd stays in solution I think that scheme is pretty smart. You need to be sure that Pd stays as a nitrate or if it converts to a chloride that the chloride is soluable.

I have no idea yet how to separate metallic Pd from metallic Ag except in a silver cell. I really don't want to get into dealing with the PGM group, at least not until I"ve done a lot more with gold and silver. I'll just save the silver I get and maybe some day run it in a silver cell which will leave the Pd as anode slimes.

I seem to be getting quite a bit more cement to drop. I used some heat for a couple of hours. I should not have said denox in last post as that requires evaporation until syrup stage. All I did was speed up the cementing with heat.

FrugalEE


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## Oz

Harold nailed it, too much nitric. 

Especially if you had some black on your copper when it “looked finished” as Pd is slow to cement to completion. Something to consider is that in your effort to cover a small amount of material (in small scale tests) with your solution you may have used the proper proportions of acid to water but used too much volume(hence too much acid). You could have kept the volume the same to cover the material, but used less acid at a higher heat or greater timeframe. 

Speaking a little bit as to the cementation of PMs and time frames. I keep all of my chloride, nitric, and sulfuric solution wastes separate after removing values. Then before I process them further for waste disposal, I cement them all to copper for a month or more. It is not a large recovery gained by doing this, but it takes little effort to do so (as long as you have not used excess oxidizing agents) before removing the base metals and then neutralizing the solution for proper disposal. As our old friend Irons likes to say “everything but the squeal”. 

More pertinent to the question at hand, when I first started making electrolyte for silver cells is where I really learned this lesson as to silver solubility in nitric at a given temperature. Since I was just learning about silver cells I wanted to be very accurate as to what my electrolyte contained so I used .999 silver to start. My silver was fine grained so should have gone into solution very readily and it is worth noting that I was using ACS grade nitric. 

However I found that taking my solutions to a warm temp (think coffee but just a little too hot to drink) and holding that temperature for an hour, left me with undigested silver and a solution that still contained free nitric acid (much to my original dismay). If you try the same thing as I did starting out, and still have silver in the bottom of your beaker, you will be amazed by how much more silver will go into solution at just shy of boiling instead of lower temperatures. It is only after staying at a temperature just below boiling for 20 minutes (based on my experience), that you can be assured of having a nitrate solution completely saturated with silver (if fine silver still remains in the bottom of your beaker) with next to no free nitric acid remaining. 

Now be aware that if you are not just trying to be sure of the complete consumption of all nitrates in a dilute solution, but have instead followed what I did above in making a concentrated silver nitrate solution. You must immediately follow your complete digestion of your silver to its saturation point at near boiling, and begin to dilute it with distilled water as it cools, or you will have a beaker filled with a solid mass of silver nitrate crystals. 

To be clear, I have not tried to apply this procedure starting with pure Pd and nitric (in this topic it seems that Pd is a possible component), but my gut instinct tells me the results would be very similar. I know I have traveled off of the path of what FrugalEE was asking, but I felt it the best way to answer his questions based on my own experience. 

I would love to hear a chemist give a more exacting explanation (a chemist I am not) and we would all learn much more than I can share. I will be honest, when I first came to this forum cementation and the electromotive series of elements rules did not seem to always follow their own laws by my own reckoning. It is only through trial and error that I have been able to make use of the concept. As an example, who here has tried to cement Pd on silver with success, despite what is supposed to happen electromotively?


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## Oz

lunker said:


> I have taken 25 square peices and have filed the plating off of them to reduce the amount of copper in solution.


That sounds like a huge amount of labor for very little reward on a $ per hour labor basis. Not that it is normally recommended, but if what I am hearing is correct that there is silver and copper in this component that is soluble in nitric and the copper is equal to or greater than the silver by mass. Someone with experience could let their waste (the copper) cement out their values (the silver) as long as they understood how to be sure that their solution was fully cemented by the copper to be sure all the silver values were removed. 

It goes without saying that you must consider “your” nitric cost as to this being a profit making venture despite the chemistry doing the job.

To be sure, if there is Pd present it complicates things, but this is easily handled with the same process if they understand testing for the values present.


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## jimdoc

This article from Ganoksin mentions testing palladium jewelry with iodine;

http://www.ganoksin.com/borisat/nenam/palladium-bench-guide.htm

Palladium Detection 
Iodine can be used to detect the difference between palladium, platinum and white gold. To use Iodine, place a drop of it on the cleaned surface of the unknown white metal. As the small drop of Iodine evaporates and dries, it may take on a body color that will assist in the detection of the metal. Here are the most common reactions you can expect with a drop of Iodine after it has dried. 

950 Palladium - Iodine turns black (as shown in example) 
900 and 950 Platinum - Iodine is mostly colorless 
14- and 18-karat white gold (below a rhodium plated surface) - Iodine turns brownish


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## FrugalEE

Oz and Jimdoc thanks for your replies. Good info, but I'm going to have to do a bit of thinking and working some more with my solution before replying to Oz. I"ve been mulling the following in my mind for some time:

*Palladium: * After catalytic convertors the biggest world use of palladium is in multi-layer chip caps. That use is to insure solderability in highly automated production.

With this clamped mica is palladium really necessary as the part is hand soldered? With hand soldering one can use a solder with an active rosin flux to take care of any minor tarnish, but most places are probably like the place I worked for where the quality folks in the 80's took away any rosin solder that had any ability to clean a joint. Also most production places will want to follow use of rosin solder with an alchohol or other solvent washing. That's not too good an idea with a part that is only semi-sealed with wax so maybe it's justifiable to plate the surfaces that are to be soldered with Pd, however I've been looking at silver plated surfaces for 70 years and these caps look like normal silver plate with it's typical tarnish. Lunker also got red color using Schwerter's silver test. 

Is there apt to be palladium on the mica? If so it would be for the purpose of maintaining a good connection as the layers are clamped together. Pd is not as good a conductor as silver and rf flows on the surface so Pd would result in more loss than Ag.

If Pd is plated on a surface that is soldered it is apt to be 50 millionths thick per Mil-P-45209b. Sometimes up to 30% Ni is alloyed with Pd plate. If used on internal surfaces for connection Pd plating could be only a flash. We should test each piece. Per Steve's data Pd should not produce any color change with Schwerter's test, but if plating is thin the base metal will also contribute to the test. I put Schwerter's on silver plated spoon and got dark color liquid indicating reaction with base metal. When I removed the liquid I had a red spot.

I seriously doubt one can make any money recovering values from these parts unless we find significant use of Pd, but this has been a wonderful learning experience.

OK, I've done my mind dump and now it's time to examine my solution which I think has gone bezerk again.

FrugalEE


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## lunker

FrugalEE,

I filed the small square peices from the insides of the caps.I understand that this is an uneconomical endevour. I am persuing this a more as an educational excercise.I don't know what the values of the parts are? And you are probably right that there is no meaningful use of palladium for these parts.it's the futile efforts that teach me the most. :lol: It's a shame though, i have hudreads of these boards.


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## FrugalEE

Oz,

I agree that I used too much acid and not enough temperature. I started with what I needed for the parts weight assuming 100% Cu (I'll bet these parts are over 95% Cu). That gave me plenty of solution to cover, but dissolving was going too slow even with warming so I added nitric. 

I didn't get any real black cement, but first cement that appeared was medium grey. I need to see some high purity Ag cement. 

I like your idea of cementing long term your wastes and I'll probably do the same. So far all wastes from everything I've done have been saved including washes except for one wash I cemented out with iron.

Right now my solution has a lot more precipitate than I got the first time I filtered out the cementations. I'm going to heat it one more time and then DILUTE about 2:1, filter off values and try cementing some more.

I still would like comment from experienced refiner on whether or not they always keep bus in place until just before pouring solution through filter to collect values. My first cement dissolved during about 30 mintues the bus was out of solution.

*Activitity series: * My list is pretty detailed, but doesn't have Pd on it. So Pd is less active than Ag, but you've never heard of anyone cementing it out with Ag?

I' m keeping track of everything used including the Cu so I can report on the economic factor.

Interesting idea using copper wastes to cement. I believe Hrusi sp? is doing just that with Cu powder.

Before doing this on a larger scale some proceedures need to be worked out. The wax has to be dealt with. I thought of incinerating, but that would probably solder the layers together. I think the parts should be taken apart and degreased (boiling water with some soap?) and the bare Cu picked out. The silver/Pd plated parts could then be deplated using a cell or some kind of leaching process.

*Lunker, Just saw your post. I got the feeling you were not in it for the money. Every part should be marked with value in front of Pf. Did you get same number of pieces in one part that I did?

*FrugalEE


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## lazersteve

The style of capacitor I posted in the beginning of this thread is not where I would be looking for Pd. Pd is used mainly in the surface mounted ones like we discussed in these threads:

Monolithic Capacitors

And they are a viable source of Pd, especially considering Pd is around $800 an ounce. 

Steve


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## FrugalEE

Steve,

Please forgive me for hijacking your thread. Go ahead and separate where I started and put in a separte thread if you like.

I just did a Schwerter's test on the end cap of a 3000 Pf dipped mica. I got yellow for tin or lead so apparently there is nothing of value in the end caps other than copper and the leads are magnetic so they can't even be sold for copper.

I doubt there are many E scrap chances to direct melt and get high purity silver as you did, especially with an 8.3% yield.

I'm going to start gathering my micas for Ag and my Monolithic caps for future Pd recovery.

Thanks for all the great info,
FrugalEE


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## lunker

FrugalEE,

Some have more, some have about the same.Some of the boards are covered in the monolithic type caps.they are soldered on the backs of the boards. they also have alot of the high grade gold parts that were shown on the forum. they look like an asprin tablet with a silicon chip inside and two rows of gold connecting wires. four wide gold plated legs that are soldered onto the board. and a copper housing or heat sink. not sure what. Will post some pics when my wife shows me how :shock: I'll get some info on there values.


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## FrugalEE

Lunker,

Looking forward to the Pictures. Those gold leads should be heavy plated UHF RF transistors. 

With the dilution and second filtering I think the cementation of my solution has finally stopped. I"m trying to get a reading on the values recovered, but paper filter is too big a weight factor and is holding the values too tight. I tried burning the filter, but there is still very light ash left over.

I weighed individual pieces of part I photoed. The 4 Ag plated mica pieces from one cap weighed .050 grams. Those pieces are easy recovery in nitric.

Catch you later,


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## nickvc

If these capacitors are basically silver plated copper my suggestion would be to harvest them then melt into bars and use for cementing silver nitrate solutions when and as you collect them, free copper for cementation and the bonus that the silver will be recovered in time and at little extra cost.


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## dtectr

Harold_V said:


> FrugalEE said:
> 
> 
> 
> I would not have expected mica to melt.
> 
> 
> 
> It is most likely being dissolved, which is a function of the proper flux when melting non-metallic substances.
> 
> The resulting metal from those caps, once collected by melting, would be excellent for inquartation, assuming it contains no lead. That way processing can be considered free, assuming one has need for silver for inquartation.
> 
> Harold
Click to expand...

 Since I wasn't sure where to include this, I thought here was as good as any. Mica is the same thing as eisenglass (not to be confused with "isinglass" a clear gelatin made from the bladder of some fish & used to clarify beer, wine & etc..), used for its high-temp resistance as well as relative clarity for stove fronts before the days of pyroceram. I am going to attempt to grind mine in my newly acquired mortar & try nitric.


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## FrugalEE

Dtectr & nickvc, Happy to see you join in. 

Dtectr, Please clarify what you are going to grind, the mica part, or the whole cap? I have already demonstrated to my satisfaction that nitric will penetrate and dissosolve all the metals in this part with it all put together and you are left with 4 sheets of clean mica. 

Nickvc, What you suggest makes sense, but most parts are going to be removed from PWBs and will have solder contamination to deal with. Wouldn't you want to get rid of that before melting into dore bar? Perhaps just heating and beating it off along with some wicking will be good enough. I don't think my swirl propane torch will melt copper, but with the help of kaowool maybe it would. So much for me to learn.

FrugalEE


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## Oz

FrugalEE said:


> Oz,
> I still would like comment from experienced refiner on whether or not they always keep bus in place until just before pouring solution through filter to collect values. My first cement dissolved during about 30 mintues the bus was out of solution.


I typically still have my copper in my solution right up until I go to recover the cemented values. That is not necessary however as long as you are sure you have saturated your solution with copper and consumed all of your nitric. With no free nitric your silver cannot go back into solution as the nitric that was present is now consumed/bound with the copper, and silver will not displace copper in a nitric solution.


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## FrugalEE

Thanks Oz, That tells me and others in just a few words how it works.


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## dtectr

FrugalEE said:


> Dtectr & nickvc, Happy to see you join in.
> 
> Dtectr, Please clarify what you are going to grind, the mica part, or the whole cap? I have already demonstrated to my satisfaction that nitric will penetrate and dissosolve all the metals in this part with it all put together and you are left with 4 sheets of clean mica.
> 
> Nickvc, What you suggest makes sense, but most parts are going to be removed from PWBs and will have solder contamination to deal with. Wouldn't you want to get rid of that before melting into dore bar? Perhaps just heating and beating it off along with some wicking will be good enough. I don't think my swirl propane torch will melt copper, but with the help of kaowool maybe it would. So much for me to learn.
> 
> FrugalEE


I'm referring to the ones pictured first in this post - the legs are, I believe lazersteve stated, base metal & therefore contamination, in my book. Its very simple to crush off the epoxy & after that, just crumble the sheets, separate the crimps/legs, then grind the residue, dissolve in nitric, filter off mica & proceed from there.

If I'm missing something, anyone, please chime in.

thanks
dtectr


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## FrugalEE

Sorry, That makes sense with dipped mica. I thought you were doing the kind I photoed. I just took the end leads off a dipped mica and that was fairly easy, but the rest is pretty well glued together with silver. Grinding will make it go much faster I'm sure.


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## FrugalEE

I took two 3000Pf dipped micas apart and put just the leadless part into nitric. The metal at the end immediatedly turned black, but in a few minutes the black dissappeared and I have fluffy white precip. That is most likely tin.

I took an even larger cap apart and took a soldering iron to the soft metal at the ends and it acts just like regular electronic solder.

One might want to treat the parts in HCL to remove solder before going to nitric or you could do a Harold fry pan roasting job later to get rid of the tin and the standard Hoke treatments for lead.


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## nickvc

My thoughts were directed towards getting a cheap method of recovering the silver due to the problem most members seem to have in getting cheap nitric. If the capacitors have other base metal contamination other than copper then maybe just use Hcl from washes and other uses to dissolve as much as possible, then rinse and then melt them, this will remove the chlorides and as cementation is a recovery method rather than refining the collected metals will need further treatment either through a cell or dissolution but on a much higher value starting material. Even if gold or PGMs are in the mix they will all be recoverable.
As one of our leading lights puts it " all but the squeak "


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## FrugalEE

Nickvc,

I like your approach to reusing as much as possible and I intend to do some of that, but you have to admit it takes more knowledge. Right now I'm trying to get a feel for different processes on various materials and doing small assay sort of operations. I tend to over think things.

I know you have experience melting copper alloys. I would love to be able to melt copper powder into a cohesive lump. At present I have a 1 inch diameter propane swirl torch, some fire brick and some kaowool. I think I could get agonizingly close on a small amount as I have brazed brass on to steel tube with it. What would I use for a flux or cheap substitute for a crucible? Charcoal?

Is there some metal one could alloy with the copper to make it melt easier? Add scrap silver? Commercial copper rod uses phosphorus, but I don't see how that could be done on small scale. 

*Two 3000Pf dipped micas in nitric: * I did nothing to reduce the solder on this experiment and I've got a lot of yogurt looking stuff from the tin and don't seem to be getting any green silver color in solution. I'm not processing anymore micas without an HCL treatment to reduce tin and lead.

FrugalEE


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## lazersteve

I would not mix the types I posted the photo of with other types. The purple style in my picture are always silver inside.

There are literally thousands of other package styles that caps can be made into, so don't go crazy mixing them all up. As I've stated before: with e-scrap it pays to sort your materials before processing. 

You will be fine mixing various sizes of the purple dipped silver mica caps, but don't mix them with other colors of caps unless you are sure they are silver inside.

Steve


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## FrugalEE

I recently discovered some caps that look a lot like silver micas, but are not. I don't think I have ever seen a dipped silver mica that wasn't basically the color in Steve's photo although some might be a bit lighter or darker.

Look at the two capacitors in front of the copper can in the photo below. The one on the left is a 1200 Pf silvered mica, the one on the right is probably a mylar. Every silver mica I've seen has had their value marked in whole numbers from 1 to 9100 Picofarads. The cap on the right has it's value .01 in microfarads and is most likely made of mylar or other plastic with aluminum foils and NO precious metals. Any decimal valued part will not be a mica. There is an orange stripe on the plastic cap, probably to help prevent confusion. There are other larger plastic caps in the photo as well where the stripe clearly shows. I wouldn't count on seeing that stripe - read the value.

If you have questions about any other capacitors please ask and I can probably help you identify it. There are other types, for example mica caps that look like dominoes, but I'm not sure if they are silvered or not.

FrugalEE


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## dtectr

Thanks for all that work, FrugalEE

I wanted to see if I am understanding this correctly - I'm a very visual learner. 

If I'm in error, please let me know so I can edit the photo 


dtectr


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## FrugalEE

Good morning dtectr,

Wow, That really points out the bad guys! I'm going to have to learn how to do thatl. What program did you use? I use photo shop, but only a few parts of it.

If someone took one of those orange striped *plastic * dielectric capactitors and hammered off the epoxy he would easily see that he had an entirely different kind of critter, but if he threw a bunch of those caps whole into a ball mill he is going to get a mess. As Steve said "Don't mix types".

Can you reference a photo of your mortar? I will probably want one as well when I get to doing ICs.

I'm still working on getting yield data on two sample runs of micas.

Frugal


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## dtectr

Mornin'!
Glad it was accurate - I didn't want to mess up your good picture. I use PrintShop to add the shapes & text boxes, then group all layers into one object. But since it only lets me save it as a .sig file, I copy & paste it into Photo Explosion (it came free with my printer, & its amazing!), then re-save it as a jpeg.

I appreciate your experience on this - I went out yesterday & began stripping these silver/mica caps from piles of old boards. I noticed slightly varying colors & descriptions, but didn't know what they meant. This will speed things up a bit.

Re; my mortar - I got it at Hobby Lobby in the kids science section!  Its a full ceramic/stoneware/porcelain (I'm not sure which description is correct), good quality really for $8; only about 2" across but will work for test batches. Sadly, it doesn't work too well on mica - its sheetlike crystalline habit resists force applied vertical to the plane, so i began just crunching them with my fingers. I haven't processed enough of them yet to move to nitric yet.

I was wondering about the purple haze (on the button, not the song :lol: ) & was wondering - since mica is sometimes mined along with galena/lead ore, could it retain some lead through processing? I don't have much experience in either of these fields, so I'm just tossing stuff out there. Maybe Rockman can chime in on the probability. Anyway, if so, it should be able to be targeted further down the road & eliminated.

just my dos centavos, adjusted for inflation, of course.
dtectr


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## jimdoc

I don't think any of the ones in the picture look like the silver mica ones. One way to be sure is break one open to see if the "guts" look like the ones in Steve's picture. I found about a ½ lb. of silver micas in my stash of junk after sorting. I found some that look similar but have an aluminum foil looking wrap inside instead of the silver rectangle pieces.
I should have a few more boxes to go through to see if I have any more, and now I know to save them when I come across more.

Jim


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## FrugalEE

I was hoping that adding boxes to photos was easier than that.

That bluish purple haze on my photo of the clamped type mica is due to poor photography and overhead flourescant light. In real life the parts look a healthy silver plated color. I'm sure the surface of the mica used was clean before silvering. I don't know what might be inside the mica, but it comes out of nitric whole and it's silver plating gone. It could be reused for something like doll house antique stove window. Lead, if present, should be left behind in the spent nitric.

In preparing your first batch you may want to look for the higher values and bigger, fatter parts. If you do only values like 10 pf you are not going to get many sheets of silvered mica. As soon as I get the mess dried I'm going to count sheets from the 3000 Pf batch. There are lots more than the four I got from one 510 Pf clamp type mica. 

Frugal


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## Irons

FrugalEE said:


> I was hoping that adding boxes to photos was easier than that.
> 
> That bluish purple haze on my photo of the clamped type mica is due to poor photography and overhead flourescant light. In real life the parts look a healthy silver plated color. I'm sure the surface of the mica used was clean before silvering. I don't know what might be inside the mica, but it comes out of nitric whole and it's silver plating gone. It could be reused for something like doll house antique stove window. Lead, if present, should be left behind in the spent nitric.
> 
> In preparing your first batch you may want to look for the higher values and bigger, fatter parts. If you do only values like 10 pf you are not going to get many sheets of silvered mica. As soon as I get the mess dried I'm going to count sheets from the 3000 Pf batch. There are lots more than the four I got from one 510 Pf clamp type mica.
> 
> Frugal



It's all a matter of area, just like in Gold plating.

I ordered some Russian Silver Micas for fun. 126,400 pf. Those should give a good yield. :mrgreen:


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## FrugalEE

Here is what I got when I filtered the digested mica capacitors. Two silver mica capacitors of 3000Pf value were hammered open, leads and end clamps removed. I did not crush the parts, but did stir during digestion. The filtered liquid was surprisingly clear instead of being green and I thought I had gotten nothing, but when I put copper in I started getting silver cement and that's still in progress.

I gave up trying to count the sheets as there are dozens. I'm wondering what that spanish peanut husk like stuff is and I'm thinking I need to stir this up good and try digesting some more to see if I got all the values.

*Irons, * I saw those on EBAY last night when I went to get a feel for the mica market. What a weird part, must have been custom made for some very special application. Anxious to hear how you make out on them.

Frugal


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## Irons

FrugalEE said:


> Here is what I got when I filtered the digested mica capacitors. Two silver mica capacitors of 3000Pf value were hammered open, leads and end clamps removed. I did not crush the parts, but did stir during digestion. The filtered liquid was surprisingly clear instead of being green and I thought I had gotten nothing, but when I put copper in I started getting silver cement and that's still in progress.
> 
> I gave up trying to count the sheets as there are dozens. I'm wondering what that spanish peanut husk like stuff is and I'm thinking I need to stir this up good and try digesting some more to see if I got all the values.
> 
> *Irons, * I saw those on EBAY last night when I went to get a feel for the mica market. What a weird part, must have been custom made for some very special application. Anxious to hear how you make out on them.
> 
> Frugal


It will be a few weeks until the weather is warm enough to work. I also ordered some of the 6800 pf orange Silver Micas for comparison. I have a feeling that the people who are selling these know what the PM content is, and are pricing the components accordingly, so, I don't expect to make anything on the experiment.

1/2% tolerance is pretty tight for that type of cap. Some precision oscillator or filter application is my guess. Perhaps it's time for a re-design of my VLF Metal Detector.


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## dtectr

FrugalEE said:


> I was hoping that adding boxes to photos was easier than that.
> 
> That bluish purple haze on my photo of the clamped type mica is due to poor photography and overhead flourescant light. In real life the parts look a healthy silver plated color. I'm sure the surface of the mica used was clean before silvering. I don't know what might be inside the mica, but it comes out of nitric whole and it's silver plating gone. It could be reused for something like doll house antique stove window. Lead, if present, should be left behind in the spent nitric.
> 
> In preparing your first batch you may want to look for the higher values and bigger, fatter parts. If you do only values like 10 pf you are not going to get many sheets of silvered mica. As soon as I get the mess dried I'm going to count sheets from the 3000 Pf batch. There are lots more than the four I got from one 510 Pf clamp type mica.
> 
> Frugal


 Sorry I was unclear - I was (still) referring to lazersteve's original posts re: melting the foils directly. The BB had a purple film after the melt.


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## FrugalEE

*Calculating yields from silvered micas: *

Irons wrote: "It's all a matter of area, just like in Gold plating." 
Fortunately mica capacitors usually come marked with a value that relates directly to area. What other form of E scrap has that feature? A 200 Pf cap will have twice as much area and silver as a 100 Pf cap. If we keep track of the total Pf values we are refining along with the yield in silver we can arrive at a number that will give us the ability to pretty well estimate the yield of a future batch along with acid required and an idea if doing the work is worthwhile economically.

*Here is an example: * 

A recent closed EBAY item: 200 capacitors of 4700 Pf value for $17. 

Multiply 200 by 4700 = 940,000. Since the numbers get so large move the decimal 3 places to the left leaving 940. 

Multiply 940 by a yield factor of .0146 grams per 1,000 Pf = 13.7 grams of silver. 

That .0146 number is strictly a guess based on EBAY price being 80% of silver spot yield. I'm hoping a number of us will keep track of their total Pf and resulting silver from batches so we can get a better number. 

*Plating thickness:*Silvering mica is very old technology and manufacturers have long since figured out how thick the plating should be. Too thick and you waste silver and the part gets bigger, too thin and stability and reliability suffer so I think that is pretty much a constant.

* Voltage rating *will have a significant effect on yield per 1,000 Pf. Higher voltages mean thicker mica sheets which reduce capacitance that has to be made up by more area.

*weight: * This is not as good a method of predicting yield especially weight of the raw potted part. I remember seeing some dipped micas where the coating was so thin you could make out where the lead was welded to the end clamp so epoxy weight varies as will lead length with some having full leads and others having almost no lead when clipped from assemblies. If we are talking about parts where everything but the mica sandwich has been removed weight should relate pretty well to yield.

*Different types of silver micas: * Using total Pf as a criteria we really don't care what kind of package the part comes in when it comes to predicting silver content.

*Parts rated in Mfd: * The common expoxy dipped parts like shown in Steve's photo stop at 9100 Pf, but there are less common large silvered micas out there marked in Mfd. Simply take a reading like 0.01 Mfd and move the decimal 6 places to the right to get Pf. 0.01 Mfd = 10,000 Pf.

*Economics: * Avoid processing anything less than about 100 Pf. When you see a dozen of something like 10 Pf sold on EBAY for $5 those parts should be ending up in circuits and not processed for silver. Only the large batches of large values should be considered for silver recovery. The way to find the best deals is to total the pf count and divide by the price. The Russian parts Irons bought wasn't the highest ratio I saw, but it was close and with the Russian reputation for being generous in the use of PMs, plus the curiousity factor, I certainly would have opted for the same parts. I'm predicting that processing silver micas is going to be more for fun than profit. I'm also predicting that Irons will squeak out a bit more silver than he paid for those Russian parts.

Any comments?

FrugalEE


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## dtectr

8) Your ability to take "university degree talk" & translate it to "real world" is a significant asset to our "Team"
I'm sure glad you're on our side :lol: 
dtectr


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## FrugalEE

Thank you dtectr, that means a lot to me. Let me know when I use some language that isn't clear. I never really felt myself part of the university crowd. I've always admired self taught individuals.

I'm still struggling to get a sample of Ag, but I'm gaining on it. Yesterday I had good cement and lost it again because I used too much acid. Also I found a few mica pieces in the puke that still had silver on them so I put it all back into solution and it's cooking.

Frugal


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## Irons

Good thinking on your rule of thumb calculations. That's pretty much how I figured it. That's why I didn't think there would be much if any profit in it. I am curious to see if there are any PGMs, since the Russians are noted for being generous in their use. As far as small lots go, it's likely to not be worth the labor but I will use any Silver recovered for Inquartation. Education is priceless.
8)


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## blkbrdpaul

WOW ! I just did a large clean up for a electronics manufacturer from a flood and I have boxes and bags galore of these and I.C.s along with a huge pile of electronic equip. guess I better start sorting !


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## FrugalEE

*Some Results: * I finally got a measure of cement silver recovered from a batch of two 3,000Pf silver mica epoxy capacitors. I recovered 78 mg total or *13 mg per 1,000 Pf.* I was amazed at how closely that compares to my estimate (prior post) of 14.6 mg per 1,000 Pf that was based on EBAY pricing. Since I figured buying on EBAY at 80% of spot it tells me you are not likely to make any money buying EBAY parts and refining them unless you get a lot better deal than they've been going for recently.

*Yield per raw weight:* The two parts weighed 5.2 grams and with .078 recovered the yield is 1.5%.

The yield results on this batch are long overdue. I kept chasing my tail because I used way too much nitric. On one occassion I had the cement with only a couple of teaspoon worth of liquid and I put some heat to it and the cement all went back into solution. I finally solved my problem by sucking off water and adding new to dilute. Of course each time I did that I needed time to settle. 

*Acid required:* Here is GSP's number for dissolving Ag: 1gram per 1.22ml of 70% nitric, but you would normally dilute your acid with an equal amount of water.

Dissolving Cu takes more than 3 times as much nitric with one gram needing 4.3 ml of 70% nitric.

*Clamped mica experiment: * This was from two 510Pf caps. I got some silver, but it's too contaminated with green salts, absorbed into filter paper, etc. to present a number.

*Working small:* When I'm processing only a couple of capacitors I need to calibrate my eye dropper (in the style of Oz) as my best graduate 10ml isn't fine enough to measure something like 0.1ml. I am getting good use out of my little scale 20 gram max with .001gram resolution. 

*Construction of silver micas: * There are two basic ways the silver is used: The best quality parts are with the silver directly depositied and fused to the mica. The second method is with the use of a thin plastic film metallized on both sides. These film pieces are sandwiched between sheets of mica of plain mica. The plastic film is NOT electically part of the capacitor. The parts that I've taken apart so far are of this latter type. The spanish peanut hull looking material s I mentioned in previous photo must be the film material.


*3160 Pf taken apart: * This is a new project. The whole capacitor weighed 4.969 grams, with epoxy removed it weighed 2.949 grams. I removed the two lead and clamp assemblies and they weighed 2.058 grams. That left the mica assembly at 0.850 grams. I put that in HCl to get rid of traces of solder. After that the capacitor was easily separated into it's parts. I removed 10 pieces of 5/8 inch square mica and they weighed .461 grams. That left .389 grams or less of silver, plastic film, and some blackened metal pieces that are probably left over solder. 

*Conclusion: *We need more data from larger batches and different people, but I think what has been posted so far should give a good idea of what is possible.


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