Silver Mica Capacitors

[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

 

[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

 

[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.

 

[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,

 

[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.

 

[dtectr]

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

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.

 

[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

 

[Oz]

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.

 

[FrugalEE]

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

 

[dtectr]

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

 

[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.

 

[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.

 

[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 "

 

[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

 

[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

 

[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

 

[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

 

[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

 

[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

 

[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