Sciencemadness Discussion Board

Extracting & separating Pt, Pd and Ag from USSR capacitors - hos is best?

plamenppp - 25-5-2010 at 06:46

I have a few kg of old USSR ceramic capacitors containing Pt, Pd and Ag. They are two types - 1. with Pd&Ag and 2. with Pt, Ag and Pd. I wonder how to extract and separate them.
I have dealt with gold from CPUs and AR many times but the capacitors are new to me. First of all I will remove as many metal legs and as much Sn/Pb solder as I can. Then I will crush them in small pieces. Then what? I believe the first step will be nitric.

[Edited on 25-5-2010 by plamenppp]

[Edited on 25-5-2010 by plamenppp]

kon1.jpg - 110kB

not_important - 25-5-2010 at 07:56

HNO3 will dissolve Ag and some Pd, unless they are in a high Pt alloy in which case they won't dissolve; so nitric acid may not be the best first step. If they do not contain platinum then go for hot HNO3, which will bring along Cu, Pb, Fe, and so on. Use HNO3 of around 20% strength. Filter the extract, raise the pH to around 5, add NaCl solution to precipitate Ag and Pb. The Pb can be removed from the ppt by extracting it with hot water.

I suspect that you will need to grind these very fine, as they are likely multiply layers of metallised ceramic; if not small enough particles then metal may be inaccessible to the acids.

plamenppp - 25-5-2010 at 09:08

I was thinking for nitric and after that for HCl and then heat to evaporate the NOx. The silver will fall down as AgCl and the rest will be converted to chlorides. For the Pt I will use ammonium chloride and for the Pd sodium chlorate. The sponges are a little hard to handle with but it is worth doing it. I expect 15-20 gr Pd and 15-20 gr Ag per kg for the blue and brown capacitors. The green ones - more + Pt.

JohnWW - 25-5-2010 at 10:42

To dissolve Pt alloys, along with all other metals present, you would need aqua regia, which is a mixture of HNO3 and HCl.
But for such rare and co$tly metals (mined in the old Soviet Union) to be in such ceramic capacitors, they must have been made at a time when they were still relatively inexpensive. When were they made, and what sorts of electronic devices did they come out of?

plamenppp - 25-5-2010 at 10:54

Quote: Originally posted by JohnWW  
To dissolve Pt alloys, along with all other metals present, you would need aqua regia, which is a mixture of HNO3 and HCl.
But for such rare and co$tly metals (mined in the old Soviet Union) to be in such ceramic capacitors, they must have been made at a time when they were still relatively inexpensive. When were they made, and what sorts of electronic devices did they come out of?


At least 20-30 years ago. They came out from various electronics. 8 bit computers, calculating machines, TVs, radios, military equipment and everything that needs electronics in it. After 1990 all most of the old equipment started to go in the trash because the communism disappeared - I am from Bulgaria. After 1990 the ones who knew what is in there and how much is it started to buy everything they could for coins. Not to mention silver from contactors - tons of it. Everything has been made with precious metals from the USSR. Now am collecting crumbs. 7-8 years ago when the Pd price has risen to more than 1000$ per tr. ounce a minority of people has made millions of it. Not to mention the Pt in some other types. Not no mention the PtRh/Pt wires in thermo-couples. Now I am doing it for the fun and to get some money I need.

Any other suggestions how to extract it? The layers are very thin. I will grind the capacitors after I break them in small pieces.


[Edited on 25-5-2010 by plamenppp]

Fleaker - 25-5-2010 at 17:26

@ John and not_important,

Be aware that platinum *will* dissolve with just nitric acid, if it is comingled with silver. Aqua regia is not always necessary, but this is a little known fact. Add it to your repertoire :)


Recall also that the solder may have values dissolved in it, but be wary of solvating it in nitric, as metastannic acid and other tin hydrolytes are a huge gooey bother!

12AX7 - 25-5-2010 at 17:27

FYI, the dielectrics will be nearly pure titania (C0G/NP0), or some combination of barium titanate and similar ceramics. There should be very little glass content (unlike more common ceramics), since these are high purity materials.

If any of these caps are multilayer (hard to say, I don't know when MLCCs were introduced), there will be thin layers of metallization sandwiched between layers of ceramic. To get at the metal, you'll have to grind it fine or dissolve everything.

If they are just metallized slabs, discs, etc., you won't have to worry about this.

Coatings should be ceramic and epoxy sorts of materials. Try pyrolyzing everything first. If it doesn't burn off, you'll probably have to grind it down anyway.

Tim

plamenppp - 25-5-2010 at 22:26

Quote: Originally posted by Fleaker  
@ John and not_important,

Be aware that platinum *will* dissolve with just nitric acid, if it is comingled with silver. Aqua regia is not always necessary, but this is a little known fact. Add it to your repertoire :)


Recall also that the solder may have values dissolved in it, but be wary of solvating it in nitric, as metastannic acid and other tin hydrolytes are a huge gooey bother!



The solder is Sn/Pb - no values for me. I am interested how to extract the Pt, Pd and Ag (Ag not so much). I must break and grind them first. The layers go like this - layer ceramic, layer metal, layer ceramic, layer metal and so on.

Burning will not help much. I've tried it - just a waste of time and fuel.

not_important - 26-5-2010 at 00:02

Ah, but if the Pt content is high enough then Ag and Pd may not be dissolved by HNO3, much less the Pt being attacked. Once upon a time I had some platinum-cobalt alloys, once of which was not attacked by HNO3, H2SO4, or HCl, although any of those simple acids should have attacked the Co, and the HNO3 both the Co and Pt by your comment.



A solution containing bromide ions, Br2 as an oxidiser, and H2SO4 or HCl, will dissolve most of the precious metals. Silver generally remains behind as AgBr but then can be dissolved, after washing to remove BR2 and acid, by treating the solids with fairly concentrated solutions of sodium thiosulfate or ammonium thiocyanate.

U.S. patent 5304359

an electrochemical method
http://www.springerlink.com/content/q7qv022m045ujn40/

chief - 26-5-2010 at 02:49

But _how_much_ is in it ?

plamenppp - 26-5-2010 at 04:57

Let's start with capacitors containing only Ag and Pd.
15-20 gr of Pd and 15-20 gr of Ag per kg.


Any ideas?

Melgar - 26-5-2010 at 14:21

I tried for a long time to dissolve platinum and only succeeded when I used aqua regia in a heated pressurized vessel. Nitric acid only dissolves platinum very slowly at temperatures below its boiling point, and unless you pressurize it, it will boil before it will dissolve platinum at an appreciable rate.

I used a champagne bottle that was fitted with a pressure-release valve, and operated the thing outside under a thick sheet of plastic. The main danger is that the bottle somehow becomes subject to high temperature gradients and cracks, but slow even heating and cooling has yet to break any bottles for me.

plamenppp - 26-5-2010 at 14:36

Let me make one thing straight! I will not dissolve thick wire of Pt. I will crush everything and after that I will grind it to dust. I will have very small particles of Ag, Pt and Pd. HNO3 will dissolve Pt if it is alloyed with something else and Pt is 1-2-3-4-5% of the alloy or if the Pt is very thin!

If you want to dissolve Pt do not use Aqua Regia! Use HCl and regular bleach as a catalytic. This works for gold too.

Any ideas how to extract Ag and Pd? Forget for the Pt for now.

[Edited on 26-5-2010 by plamenppp]

Sedit - 26-5-2010 at 21:12

Can you show how to tell which have the precious metals in them? I have a ton but always assumed Al was used for the plates since other then impeadence conductivity is not really an issue in Caps.

12AX7 - 26-5-2010 at 21:15

Aluminum is used in metallized film capacitors and electrolytics. I don't think it has ever been used in ceramics. Although it seems a likely candidate, it might be that it oxidizes during processing, or it doesn't match thermal expansion or something. I've heard Ni, Pd and Ag are used.

Tim

plamenppp - 26-5-2010 at 22:50

Quote: Originally posted by 12AX7  
Aluminum is used in metallized film capacitors and electrolytics. I don't think it has ever been used in ceramics. Although it seems a likely candidate, it might be that it oxidizes during processing, or it doesn't match thermal expansion or something. I've heard Ni, Pd and Ag are used.

Tim


If the ton is from USSR capacitors post a picture and I will tell you which ones contain precious metals.

not_important - 26-5-2010 at 22:53

Quote: Originally posted by plamenppp  
...
If you want to dissolve Pt do not use Aqua Regia! Use HCl and regular bleach as a catalytic. This works for gold too.


This is effectively the same as the acid-bromide-Br2 method, with OCl(-) as the oxidiser instead of Br2. It is not catalytic, there is a definite stoichiometry for element.
Quote:

Any ideas how to extract Ag and Pd? Forget for the Pt for now.


Already said it - use moderately strong (10-20%) HNO3, slowly heat with good stirring, cool, raise the pH to above 2 using NaOH or Na2CO3, add NaCl solution to precipitate AgCl. Too acid and more of the AgCl stays in solution, as will happen with a large excess of chloride. Wash the AgCl ppt twice with water containing a little NaCl or a drop or two of HCl, add the washes to the filtrate, work filtrate up for Pd by any of a number of methods. If you think there is Pb in the material, cover the AgCl with water, maybe 10 times the volume of the AgCl, and heat it to boiling, then filter while hot to remove the PbCl2. If crystals appear on cooling of the filtrate, extract the AgCl once again.



Sedit - 27-5-2010 at 11:20

Quote: Originally posted by 12AX7  
Aluminum is used in metallized film capacitors and electrolytics. I don't think it has ever been used in ceramics. Although it seems a likely candidate, it might be that it oxidizes during processing, or it doesn't match thermal expansion or something. I've heard Ni, Pd and Ag are used.

Tim



So your suggesting that all ceramic caps have something such as this in them? What alternatives to Pd would there be since I have a TON of these around. You say silver and Nickle but what is the most likely candidate for the material in these? Seperation would be a snap using a fan and static electricity. Grind the caps. Place them on a charged plate and bring another charge wand near it. All the plastics and ceramic powders would fly away leaving the metals behind. I just ran an experiment such as this a few days ago with small brass pieces and sand. Worked better then I would have thunk.:D

12AX7 - 28-5-2010 at 16:50

Ha... but did you happen to try it with brass-metallized sand?

Tim

not_important - 28-5-2010 at 16:59

Yeah, I think that will be the problem with that approach, the metals are thin films on the ceramic - rather well attached and not likely to be split off by anything less than grinding to extremely small size.

Sedit - 28-5-2010 at 19:12

Quote: Originally posted by 12AX7  
Ha... but did you happen to try it with brass-metallized sand?

Tim


.......What?


You wanna get an idea what im talking about get two metal plates with a gap inbetween. place styrofoam and small bits of Al foil on the lower plate. Hook the plates up to a 10k 24ma OBIT and observer the seperation of metal and non metal take place.

If you think my idea is silly perhaps you should look into how the bigboys seperate the ceramics from the metals in computer parts and capacitors and such on a large scale. Mine is nothing more then a desk top variation of the industrial methods they use.
~Sedit

12AX7 - 29-5-2010 at 02:35

As I recall, they use eddy currents, not electrostatic?

It'll work, but my point was, how do you decide which particles are 100% metal and 100% ceramic when both are intimately combined? You'd have to grind it to micron particle size to guarantee that.

Tim

Sedit - 29-5-2010 at 09:12

The method I seen they just take computers boards and grind them to a dust. Then on a conveyer belt they spray a charge onto the passing material. At the end they have two bins and a charged plate. The metals drop into one bin and the non metals fly into another bin. It was all electrostatic based.

My thoughts for doing this where not so much as a primary mean of seperation but more or less a first step to thin the field so your not treating tons of nothing but ceramic with various reagents leading to losses.

A ball mill would come in handy here well and I see no problem powdering them this way then passing a magnet to remove any possible Fe contamination and further process it however on wishes.

Non metals should stick to a charged plate so im thinking if you vibrate a pile of this power on charged plate the metals will slowly fall out. I got some capacitors so give me abit of time and I will have at it and see what I can come up with, Experimentation is King.

Some Links regarding pd/ag content etc

SWilkin676 - 10-6-2010 at 05:41

I was curious about which components had what kinds of metals also so I did some research and found this really good article. The are typically ceramics with layers of very thin metal fired inside.

I thought I saw an article that estimated 15-30% pd content (circa 1983) but they might have meant of the metal part not the whole capacitor. Another article said the metal used was 70% silver, 30% palladium. The year of manufacture is probably important as well since there have been spikes in pd prices which would have cause manufacturers to look for alternatives.


Alloy and Core Shell SIlver/Palladium Platlets for Ultra-Low Fire MLCC's

Reliability of Multilayer Capacitors

[Edited on 10-6-2010 by SWilkin676]

SWilkin676 - 3-7-2010 at 05:43

http://www.goldrecovery.us/site.asp

This site has some great videos on metal recovery methods and testing.

Suzee