Interesting ceramic discs on old boards. Silver and/or palladium perhaps?

[Alondro]

I have a bunch of these old industrial boards. There are HUNDREDS of these discs, which I'm assuming are capacitors given how they're all in circuits with resistors. I'm hoping they're good! Also found several of those gold-rhodium plated tube relays on these, an unexpected find, and the first I've ever come across!

There are other components on these boards I don't recognize, but not too many in number. I'll see if I can figure them out when I take them apart. These discs are the most plentiful components aside from resistors, so they're most important to identify conclusively.

 

[Yggdrasil]

Looks like a Hammond board
I always took these as alu disk capacitors, but may be wrong.

 

[Alondro]

Looks like a Hammond board
I always took these as alu disk capacitors, but may be wrong.

Yes, they are Hammond boards, from a broken organ.

The internal ceramic disc has a layer of a soft silvery metal coating both sides. The metal is soft and flexible when I peel some of the layer loose.

I put a fragment of the metal coated disc in HCl, and the metal is very slowly dissolving and turning black. I compared with a little piece of known aluminum, and it dissolved much faster, and more vigorously. In fact, the aluminum is long gone in its tube, while the coating still hasn't finished dissolving. So I don't think the mystery metal is aluminum. Since it's soft, could it be lead? Silver-lead alloy? Or maybe a tin coating?

Let me see, if it's lead, a drop of sulfuric acid would create a white precipitate, and tin will give no precipitate.

What other metals are soft and ductile, and dissolve slowly in HCl, turning black on the surface first?

 

[war_child]

Hello Alondro. I thought those bords looked somewhat familiar. I too scrapped out a Hammond organ recently. I was wondering if you came across some of the same components I found. The organ I took apart had a Leslie speaker but did not have a tone wheel. I think I found some palladium threads under the finger keys and foot pedals. This organ had many boards, and a lot of the boards had connector fingers made from a silver/ tin color. I was wondering if they could be palladium also, though I think there probably just tin. I have them set aside until I'm sure about all the components.

Another part I was wondering about is some contacts I found. They are a silver-looking, "bar" shaped contact, but the silver is very clean looking. I would expect silver to have some noticeable tarnish after nearly half a century. Can you confirm these to be silver?

Happy Scrapping!
mike

 

[kurtak]

https://goldrefiningforum.com/threads/10-grams-of-scrap-palladium-in-hammond-organ.29334/

 

[kurtak]

https://goldrefiningforum.com/threads/please-help-id-pms-in-another-hammond-organ.30454/#post-318932

 

[kurtak]

https://goldrefiningforum.com/threads/hammond-e-111.14161/#post-142220

 

[kurtak]

The Pd wire (in Hammond organs) on the tips of the contact point(s) bus bars & the Pd wire on the (long) bus bar where the points make contact is where "most" of the value in a Hammond organs is

the only other real values are the IC chips on some of the CBs & the Ta CAPs

Other then that little or no value in other components - certainly no values worth "chasing"

IMO - chase the values known (& worth chasing) - (as described above) & toss the rest in your LOW grade scrap

Kurt

 

[Alondro]

Hello Alondro. I thought those bords looked somewhat familiar. I too scrapped out a Hammond organ recently. I was wondering if you came across some of the same components I found. The organ I took apart had a Leslie speaker but did not have a tone wheel. I think I found some palladium threads under the finger keys and foot pedals. This organ had many boards, and a lot of the boards had connector fingers made from a silver/ tin color. I was wondering if they could be palladium also, though I think there probably just tin. I have them set aside until I'm sure about all the components.

Another part I was wondering about is some contacts I found. They are a silver-looking, "bar" shaped contact, but the silver is very clean looking. I would expect silver to have some noticeable tarnish after nearly half a century. Can you confirm these to be silver?

Happy Scrapping!
mike

I only have the circuit boards, which I got from my main supplier of scrap. A bar should be easy to test. Scrape a few filings off and drop them in nitric. They should dissolve without any precip and make a light blue solution (silver in use is most often alloyed with copper, or over top of copper). Then drop a little salt solution or HCl into it. Fluffy white precip forming instantly means it's silver.

Oh, to update on the metal film inside the discs, it's even MORE of a puzzle now. After overnight, the HCl solution is a very pale violet (you can only see the color when the tube is held up to bright light) and what remains of the metal is no longer reacting, and is completely black. The pale violet solution is strange and very unexpected... I've only seen that color with dilute indium, cobalt, or vanadium solutions, but I have never read that those metals were used in disc capacitors.

It also melts at a very low temperature. I burned a few pieces to weaken the ceramic so I could remove it more easily, just between 2 small bits of cardboard... and that was enough to make the metal film melt and drip off! So, not cobalt or vanadium. Indium-tin alloy? Aluminum and something else that makes pale violet as a chloride?

One component is either unreactive to HCl or it's chloride is insoluble in HCl, or hydrolyses and becomes a hydroxide or oxide that's black and insoluble. I'll have to test with nitric next.

 

[Alondro]

The Pd wire (in Hammond organs) on the tips of the contact point(s) bus bars & the Pd wire on the (long) bus bar where the points make contact is where "most" of the value in a Hammond organs is

the only other real values are the IC chips on some of the CBs & the Ta CAPs

Other then that little or no value in other components - certainly no values worth "chasing"

IMO - chase the values known (& worth chasing) - (as described above) & toss the rest in your LOW grade scrap

Kurt

Two boards I got seem to have some additional values. One board has sections for different instruments: oboe, flute, trumpet, clarion; so I'm guessing that's a 'synthesizer' board. It has some gold-plated transistors and some little tuner knobs with silver-plated leads and innards.

The second board has rows of little brown, lumpy ceramic capacitors. I broke one open (as you can see in the pics) and there's a soft metal sheet inside which was partially curled around compressed black metallic powder. Going to toss the opened one into HCl and see what happens. Probably aluminum sheet-zinc powder, with the zinc oxidized since the boards had been wet for a while before I got them, buuuut, just in case I'll do a test!

Since a couple of these boards had a few unexpected gold and silver components, better test everything except the aluminum canister capacitors. I found a way to melt out and recover a lot of the aluminum from those with nothing more than a simple cast iron pipe surrounded by a wood fire, and round brick weights I slip inside the pipe to press the material as it heats. The molten aluminum flows out, down a little brick ramp where I can collect it, then melt into ingots.

It's just satisfying to see what would be trash turned into nice blocks of shiny metal. :]

 

[Alondro]

The little brown capacitors insides didn't react much with nitric, only the black powder did a little. The bright metal reacted swiftly with HCl, so looks like they're just Al type capacitors. Though, the black powder doesn't fit. Aluminum, zinc and tantalum oxides are white. Manganese oxide is coal black, so maybe that?

The YELLOW ones, however, get more perplexing with each test. The metal film over the ceramic disc reacts with nitric much better than with HCl and dissolves completely, so it's NOT aluminum at all! It forms a small amount of whitish precipitate as it dissolves, but far less than can account for all the metal. So the alloy is either tin or bismuth, forming oxynitrate, and some other metal I still haven't identified.

No sign of obvious palladium nitrate coloration in the solution. I'll do a stannous test to be certain, but looks like I can exclude that.

When it settles, I'm going to take some of the clearest part of the nitrate solution, drip them into two glass tubes, and add a drop of HCl to one and a drop of sulfuric in the other. That should give me a positive result for either silver or lead.

If there's even a little silver, I'll process all the discs. I have so many from these boards which I got basically for free, lumped in with a pile of other scrap I bought, that the silver will add up. I've found an easy fire-based method to crumble the resin coating so the acid can attack the metal.

It still leaves the mystery of the pale violet in the HCl solution. I'm thinking there might be a reaction with the ceramic disc material itself, which could be composed of a titanium oxide-cobalt oxide ceramic. A little might dissolve into HCl and form CoCl2, and that would explain the very pale violet color.

 

[orvi]

Brown disc capacitors could possibly contain some little silver, but there is more often not economically viable ammount. Nitric should tell.

To the other caps (with black powder inside) I have no answer what it could be. Very strange and odd looking.

Violet could be cobalt, but also sometimes resins (mainly phenolic type) could leach violet colour in acid.

But nice transistors and tantalums on the board anyway

 

[Alondro]

Brown disc capacitors could possibly contain some little silver, but there is more often not economically viable ammount. Nitric should tell.

To the other caps (with black powder inside) I have no answer what it could be. Very strange and odd looking.

Violet could be cobalt, but also sometimes resins (mainly phenolic type) could leach violet colour in acid.

But nice transistors and tantalums on the board anyway

Hmm? Tantalums? Which ones are they? Is that what the yellow discs are? Or do you mean some of the components from War_child's boards?

Yeah, the transistors were a nice surprise. I haven't checked the whole box of the boards yet to see if there are more. There are also a bunch of golf-ball-sized iron ceramic cylinder components that actually have a lid held on with a screw! You unscrew it and the lid comes right off, revealing the copper coil sitting inside. Convenient!

Regarding my ongoing tests on the yellow discs, 50% nitric acid followed by drops of sodium chloride solution led to a weird result with little no additional precip, but changing the color of the soln to a light yellow-brown, until I diluted it with a little water, then a TON of white precipitate formed. I then stuck a piece of clean copper in, and spongy grey metal reduced on its surface. Now I'm quite perplexed.

I think I need to try again with a disc in sulfuric. I think there are too many metals in the electrode's alloy and maybe leaching out of the ceramic that have reactions with nitric, and could be forming complexes with other metals, that are difficult to clean up.

I'll dissolve the metal in sulfuric, reduce with copper, then RE-dissolve whatever metal reduced out in nitric, and then I should be able to test it. That'll take a couple days, since I only do sulfuric acid stuff outside in nice weather... and it's stormy today.

 

[orvi]

Hmm? Tantalums? Which ones are they? Is that what the yellow discs are? Or do you mean some of the components from War_child's boards?

Yeah, the transistors were a nice surprise. I haven't checked the whole box of the boards yet to see if there are more. There are also a bunch of golf-ball-sized iron ceramic cylinder components that actually have a lid held on with a screw! You unscrew it and the lid comes right off, revealing the copper coil sitting inside. Convenient!

Regarding my ongoing tests on the yellow discs, 50% nitric acid followed by drops of sodium chloride solution led to a weird result with little no additional precip, but changing the color of the soln to a light yellow-brown, until I diluted it with a little water, then a TON of white precipitate formed. I then stuck a piece of clean copper in, and spongy grey metal reduced on its surface. Now I'm quite perplexed.

I think I need to try again with a disc in sulfuric. I think there are too many metals in the electrode's alloy and maybe leaching out of the ceramic that have reactions with nitric, and could be forming complexes with other metals, that are difficult to clean up.

I'll dissolve the metal in sulfuric, reduce with copper, then RE-dissolve whatever metal reduced out in nitric, and then I should be able to test it. That'll take a couple days, since I only do sulfuric acid stuff outside in nice weather... and it's stormy today.

The black axial SPRAGUE ones. They look like tantalums on the photo. If they are heavy, you have the right thing.

If anything is precipitating on copper, that is a good sign.

Usually with resin-dipped cap stuff or the stuff like your brown-ones, testing is done by incinerating few pcs to ash, crushing to powder and only then leaching with nitric.

 

[trdking]

Keep at those disc caps My buddy processed a few thousand of them and he said they were good I forget what he pulled from them but I can ask him if you wish. He did incinerate them and then processed the ash. You didnt find a thin layer of gold in the aluminum caps? I have been told they carry a small amount of gold?

 

[Ohiogoldfever]

Easiest way to quickly check the Silver caps for Tantalum is to try and crush on with pliers or whatever your snipping components with.

If aluminum they crush super easy. If they are hard as a rock, tantalum.

Love me a Hammond.

If you get one with the slide switches they are loaded with silver. Two solid contacts on the slide and solid buss bars they contact.

I should have a picture here..... the bar I’m talking about is the black one on the far left of the photo.

 

[Alondro]

The black axial SPRAGUE ones. They look like tantalums on the photo. If they are heavy, you have the right thing.

If anything is precipitating on copper, that is a good sign.

Usually with resin-dipped cap stuff or the stuff like your brown-ones, testing is done by incinerating few pcs to ash, crushing to powder and only then leaching with nitric.

The black Sprague ones are about 3 grams each. That does seem fairly heavy for a plastic cased capacitor, but not as heavy as I'd expect for tantalum of that size. Maybe the wet electrolytic type? Then it'd be tantalum foil with wet paper, which would lower the overall density. Those are kind of a pain to identify. The one company that buys tantalum caps posted pics of a number of them, and some look almost the same as plain aluminum foil ones. Very tricky unless you have the EXACT same model number and manufacturer

Yeah, even the tiny piece I dissolved from the disc caps made enough metal cement out on copper that I was able to polish it to a bright silvery shine!

I'm really leaning to palladium as the identity of the metal, since the nitric solution had a pale yellow-brown tint, and nothing came out with adding concentrated sodium chloride.

Looking at the small pieces I put into HCl, there's a exceedingly thin plating of the metal right at the surface of the ceramic, and then I guess tin is layered upon that, which is what dissolved off in the nitric and made goo. The super-thin plating turned from black to dark grey and is very, very slowly dissolving away in the HCl, over the more than 24 hours it's been sitting in the conc. HCl. But then oddly enough, I'm also seeing tiny super-bright silvery crystals of metal regrowing at the edges of some of the pieces. If only I had a microscope camera to get a picture!

At the very least, these are worth doing in a larger batch, enough that I can determine the mass of PM. Since it has to be either silver or palladium if it's a PM (they're the only common enough ones that dissolve in nitric), I think sulfuric is the best bet, since it'll get the tin out of the way AND dissolve the PM at the same time.

Yeah, I'll do a burn on a bunch of disc caps to get rid of the organic resins. I have a steel screen I use for that, over a wood fire. We have TONS of sticks and scrap wood around here! No cost at all!

 

[Alondro]

Easiest way to quickly check the Silver caps for Tantalum is to try and crush on with pliers or whatever your snipping components with.

If aluminum they crush super easy. If they are hard as a rock, tantalum.

Love me a Hammond.

If you get one with the slide switches they are loaded with silver. Two solid contacts on the slide and solid buss bars they contact.

I should have a picture here..... the bar I’m talking about is the black one on the far left of the photo.

I was looking at all the pics from the company that buys tantalum caps, and there are wet electrolyte-tantalum foil types as well. The casings in the pictures of those looked like aluminum, and because the foil is wrapped up with electrolyte-soaked paper, the overall weight doesn't feel very heavy. Seems that type may be tricky to positively identify.

Need a magic tantalum-identification spell, lol.

 

[Alondro]

Keep at those disc caps My buddy processed a few thousand of them and he said they were good I forget what he pulled from them but I can ask him if you wish. He did incinerate them and then processed the ash. You didnt find a thin layer of gold in the aluminum caps? I have been told they carry a small amount of gold?

Might be a specific type of aluminum cap that has a little gold plating. I've been wondering about those that come in odd colors, like grey, orange, green, red, violet, and yellow. Most of the modern aluminum electrolytic caps were black or blue... so what do those other colors mean? There must be some reason a relatively small number were various other colors.

As for ceramic discs, it seems the best bet is to just test a batch of any I have a large number of, and then lump the smaller numbers of different ones in somewhere. The composition varies so much, testing each little variant would be horribly inefficient. Since silver and palladium are the most common of the PMs found in the discs that have PMs, I could do a method I'm seeing in chemistry research papers: sulfuric acid/sodium chloride leaching.

Here's a presentation with a comparison of many methods, proposing the new method as optimal for both efficiency and waste stream considerations: https://www.researchgate.net/public...m_Palladium_and_Rhodium_From_Catalyst_Residue

Looks like the best method is to grind and wash the material, boil in distilled water for at least 2 hours to get rid of soluble salts, then dissolve the metals with 60% sulfuric and about 0.1M NaCl solution, then let that solution heat with the metals for at least 10 hours at around 125C. With that protocol, the researchers obtained about 97-99% extraction of PGMs from powdered catalytic converters.

Then the question is, does the Pd reduce easily via cementing and/or what reducing agents need to be employed in such a solution to recover all the dissolved Pd?

 

[kurtak]

The black axial SPRAGUE ones. They look like tantalums on the photo.

Those black SPRAGUE CAPs are NOT tantalum !!! --- Edit to add; - at least I don't believe they are

Why ?

Because Ta Caps are inherently polarized - meaning that the vast majority of Ta Caps have a positive & a negative lead

So - one why to identify Ta Caps - & something they have in common is that most all of them (if not all of them) is that the positive lead - & the positive lead ONLY is identified one way or another

one example - Tantalum Capacitor Polarity Markings

another example -

& some more examples

Note the bullet shape

Note the *** on one end

note the + sign the ring & *** all on one end

note the white bar & shaved end

Note the bar on one end - if they are "black" with NO bar they are NOT Ta Caps

red ring on one end

note the *** on one end

Most other (aluminum) polarized Caps are marked with BOTH the + (positive) & the - (negative) lead - or can be identified because they don't have the solid Ta pellet inside them (so crushing them with a pliers will identify them

There are non-polarized tantalum Caps but they are far more rare

Some examples ------

For what its worth

Kurt