# Thoughts about ceramic capacitor recycling



## SapunovDmitry (Nov 27, 2013)

Gentlemen.
I have recently got the task from my boss about possible ways of the recycling of dismantled ceramic capacitors.
Then i have studied possible ways of refining including chemical and metallurgical methods.
I ended up with two possible methods of mass refining.
1. Dissolution of capacitors in AR with washing them in it until no or almost no PGM are present in solution. Then filtering it out, increasing pH to 7 with NaOH water solution and then converting base metals into formates (since Zn, Pb, Cu, Ni and Ba formates do dissolve in water) and PGMs into their metallic state. Then filtering out formates. Washing the powder and smelting it in the induction furnace.
This is the standard approach and that i am sure many of us are aware of.

Now the second one.

2. Filtering ceramics is dull and working with barium chloride salts is dangerous. So.... Crush capacitors into -0.2 mm powder, mix it with soda, borax( optional) and SiO2 and put it in your induction furnace and heat it up to 1300-1500 C (Slightly reducing atmosphere). Since the melting point of Pd is about 1500-1600 C and there is some copper,nickel, tin and lead in capacitors so melting point of the mixture will be not so high. This way you do not have to work with the ceramics and you get pretty nice bar of metal. We ended up with Pd content about 50% , Cu - 20%, Pb - 20%, Ag - 5-7%, Zn - 2%. Since you have got a bar you can melt it into rods and use electrolysis to refine your Pd or dissolve it using nitric acid and converting metals to their hydroxides and then again using formate process.

Post your comments. Advises are welcome.


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## 9kuuby9 (Nov 27, 2013)

Their is an alternative to the second option, Melting the ceramics with the correct fluxes and casting the mix in a pre-heated cone mould.

Take a look at this thread; http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=39&t=19537 (skip the yield discussions)

And these too; http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=11490#p112545
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=60&t=5871#p50658

Their is plenty of good information in these threads about the process.

I do not recommend the first method, You are Starting with AR? that's a no go to be honest. especially when their is a large amount of base metals.
And You will never fully recover all the values when using a chemical leach. I've personally used Chemical leaching for leaching values from _Ceramic_ containing material, And it was frankly an endless process with no or very small amount of success. The ceramics are very insoluble and can passivate and trap values Especially when Palladium is involved.

Since you already have Copper into the mixture, I would advice to add copper as a collector.
You would only need a furnace capable of reaching 1200°C .
Process and then collect the values as slimes from the copper sulfate cell. (Cu content must be <96%)
The Pb should drop as insoluble Lead Sulfate in the anode bag if I'm not mistaken.


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## johnny309 (Nov 29, 2013)

Came across the same....let's say(in my case future ..)....so......let's be short:
1)input material.....is containg silver,Pd,ceramics(alumina..Al2O3...which is inert and non reactiv to acids......barium and titanium oxides...)
2)resin who seal the capacitor...which the only method is burning...but the resulting carbon residue will "catch" the PM
3)attaching the "leads"...cooper conductors...they used Sn-Pb (70-30) solder.......


So basically ...is a mix of metals....

P.S.:I still study the PARKER process ......


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## 9kuuby9 (Nov 29, 2013)

"johnny309" Are you describing 3 different materials or are you describing a "possible way" to process _a_ material?

Please try leave the needed amount of information, so members don't have keep asking for more details.


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## johnny309 (Nov 29, 2013)

Just couple of pictures...if I want to translate from my native language to english...it will take a couple of days.....,but...in the '70-early '90...ceramic capacitor was made by using electrolyte(think as the "insulating" to increase capacity per volume) ..alumina...Al2O3....inert and very stable with temperature ..
On each side they deposit a layer of "collodial" silver..(in fact a carbonate of Ag decompose in high temperature).

They were made with Al "plated" on ceramics in high frequency and in vaccum(no oxigen,just inert gases) enviroment..

I have some documents,but do to the fact that they are in an foreing language(romanian)......it will take me some time to post the document....


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## SapunovDmitry (Dec 8, 2013)

Allright Gentlemen,
I was missing due to capacitor smelting but now i am back and eager to discuss the results.
I was working with old Russian Pd capacitors and here are the results:
Refining plant states that the Pd content in those capacitors is 5-5.5% and Pt is 0,1-0,4%.
Smelting those with right fluxes (similar to those advised by 9kuuby9, but with respect to the current material) gave us 5,8-6,1% of Pd and 0,4-0,65% of Pt plus 0,05-0,1% of Rhodium confirmed by the same plant and reduction of payment delay for the metal from 95 days to 25 days.
End of the story.
Morale: Use induction heating and right fluxes for your capacitor refining and NEVER, i repeat, NEVER use chemistry when fragile ceramic is involved (because if you have oxides which can be converted to slag you better do so instead of trying to filter out PM salts from muddy ceramic residue). I want to note that if you DO want to make very pure metal you are likely to use chemistry but this time with no ceramic involved.
Also i would like to enclose a shortcut to the best and the most simple explanation of how to make the induction heater (although we used a commercial one it was much like the one described there).
http://www.instructables.com/id/30-kVA-Induction-Heater/


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## 9kuuby9 (Dec 8, 2013)

As SapunovDmitry Confirmed, Never use a chemical leach when it comes to recovering pm's from ceramic containing materials as explained in the posts.

I do have a few questions regarding the melting procedure you used,

Did you use a collector such as Copper or Silver? Was the material crushed? and what temperature did the induction furnace reach and how many hours was the running cycle per melt?

The more you tweak your process the more Pm's you are able to recover from the ceramic material.

And also do a fire assay on the slag, as their still might be some values left before disposing of it.

And thank you for sharing your findings "SapunovDmitry", I really do appreciate that.


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## 4metals (Dec 9, 2013)

I would add one thing to the flux to make it much more effective, Cryolite. This will help dissolve the ceramic to make the flux more liquid and less likely to hold up finely divided metals. Without this you are not dissolving ceramics only floating chunks, any metal which is encased in ceramic will not be collected without it.


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## 9kuuby9 (Dec 19, 2013)

4metals said:


> I would add one thing to the flux to make it much more effective, Cryolite. This will help dissolve the ceramic to make the flux more liquid and less likely to hold up finely divided metals. Without this you are not dissolving ceramics only floating chunks, any metal which is encased in ceramic will not be collected without it.




I recommended your flux recipe that you used to melt ceramic substrates with back in the '80's. I'm unsure however if he did use Cryolite in his flux recipe.

I wonder however if this would work with low yield crushed PM ceramic containing material? Probably adding a collector would be the best way to go.


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## 4metals (Dec 19, 2013)

Cryolite is hexafluoroaluminate you could substitute fluorspar. Cryolite is a natural ocurring mineral, there is a synthetic made as well which was once called Kryolite but I could not find references to it other than links calling them both the same thing. Cryolite would be preferred over fluorspar.


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## Tub Buster (Jan 10, 2014)

SapunovDmitry said:


> Filtering ceramics is dull and working with barium chloride salts is dangerous. So.... Crush capacitors into -0.2 mm powder, mix it with soda, borax( optional) and SiO2 and put it in your induction furnace...



The ceramic has a low specific gravity, so some sort of gravimetric separation like a centrifugal bowl might work.

Anyway, the reason I'm posting is that no one caught the reference to barium chloride. This salt melts somewhere around 1100 deg C., so it is often used in heat treating, but can also be used for separating metals. GoldSilverPro posted elsewhere about a process developed by the U.S. Bureau of Mines for separating copper in motor armatures from the steel framework. You heat to 1200 deg, dip the armature in for 9 minutes, and the copper falls off. The interesting part of that report was the economic evaluation, that showed the technically superior method of using BaCl2 with NaSO4 pretreatment was not worth it, due to ancillary costs (labor, etc.). Instead, it was just as effective economically to use Calcium chloride (rock salt) with no pre-treatment.

Use of CaCl2 avoids the barium toxicity issue, but of course the chloride vapors are still a problem.

The point of all this is that the technique is within reach of anyone with a Kerr electromelt furnace or the equivalent. It useful for separating two or more different metals. All of the comments made in this thread about ceramics still apply, but I thought I'd bring some attention to the technique in case it has application elsewhere.


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## etack (Jan 10, 2014)

That sir was a very old topic(2010ish). Can't say you haven't read the archives. 8) 

Thanks

Eric


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## CBentre (Jan 14, 2014)

Also brought up an interesting fact in regards to the armature. I always wondered how to get that copper out...I have a skid that hasn't moved in almost three years. Thanks


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## Smack (Jan 15, 2014)

I'm thinking you would have to preheat the armatures as well so you don't have an explosion when the armature is introduced.


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## CBentre (Jan 17, 2014)

Smack that is probably a good enough reason for me to just leave it for the big boys. There is some nice looking copper in semi truck starter armatures but sometimes it's just not worth the hassle. Thanks


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## Tub Buster (Jan 25, 2014)

I uploaded the Bureau of Mines report to Scribd for those who would like to read it:

http://www.scribd.com/doc/202209509/Separating-Copper-From-Scrap-by-Preferential-Melting

Also I ground up some ceramic capacitors in a mortar and classified to 1/8". Most of the metal was in the larger bits. I washed the fines down in a gold pan, and the result is shown below. 

That's as far as I went, as I really don't know what I'm dealing with. I'll just store it for the time in the future when I do.


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## Yellowdevil (Feb 16, 2014)

You want to know how Russian recycled ceramic capacitors? 

At the plant melted with potash schelochyu. 

And other chemists, crushed, soaked in hydrofluoric, acid-etched, filtered and separated.


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## butcher (Feb 16, 2014)

potash schelochyu?

Is this K2CO3, KOH, or one of the other potassium salts?


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## Yellowdevil (Feb 17, 2014)

KOH


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## 924T (May 8, 2014)

Tub Buster,

This could be done in a Kerr Electromelt?

Any idea what the run time would/should be for a smelt like this?

Would the smelt run time be less in an induction melter?

I talked with RDO Induction a couple of years ago, and specifically asked them if one could smelt in
their induction units, and they said they didn't recommend it, so I'm trying to figure out how Dmitry
is able to do just that on an ongoing basis.

I did find a source for synthetic Cryolite up in Minnesota, but I forgot to write the name of the
place down------I'll look it back up and post the link. If I remember correctly, you could get around
10 lbs. of Cryolite from them for what 1 lb. is going for on ebay. They also have pints of 70% Nitric Acid
for around $12, which seemed pretty reasonable to me.

Thanks for any/all commentary/ideas on this!

Cheers,

Mike


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