# old Fe/Ag tantalum capacitors - any hack for scrapping these ?



## orvi (Feb 9, 2022)

Hello
just a quick question. 
Do anybody know (and be willing to share) some easy way of scrapping this type of capacitor ? Metal jacketing is some sort of painted steel (magnetic), it consists of two pieces pressed together to form tight seal. In the "skinny" part of the capacitor, there is underlaying thick silver foil, and in the "wider" part there is tantalum disc. It is pretty labor intensive to manually saw them one after one, and pull the silver+tantalum out. Not feasible on larger scale. 

I considered leaching out the iron with some acid, leaving the silver, but this would be quite acid-consuming. Piece weights around 3 grams and inside is like 0,5g Ag. Tantalum equally much as silver, so it is nearly 2 grams of iron to be dissolved...

Thanks in advance for any suggestions
orvi


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## snoman701 (Feb 9, 2022)

nitrosulfuric acid, precipitate ag as agcl with hcl


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## macfixer01 (Mar 30, 2022)

orvi said:


> Hello
> just a quick question.
> Do anybody know (and be willing to share) some easy way of scrapping this type of capacitor ? Metal jacketing is some sort of painted steel (magnetic), it consists of two pieces pressed together to form tight seal. In the "skinny" part of the capacitor, there is underlaying thick silver foil, and in the "wider" part there is tantalum disc. It is pretty labor intensive to manually saw them one after one, and pull the silver+tantalum out. Not feasible on larger scale.
> 
> ...




Probably not the answer you want to hear, but escrap channel just did a video on these and he’s cutting them open around the edge with what looks like some sort of Dremel type tool. I don’t know if a Makita type grinder with a thin stone or saw blade would possibly be faster? Anyway it doesn’t look like that bad a process. You could make some sort of a jig to hold the saw and capacitor so all you had to do was rotate the capacitor? Take a look and see what you think?


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## MicheleM (Mar 30, 2022)

Could be a coincidence? Perhaps @orvi is him. escrap YouTube channel is one of my favourite!


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## orvi (Mar 30, 2022)

MicheleM said:


> Could be a coincidence? Perhaps @orvi is him. escrap YouTube channel is one of my favourite!


Very interesting video. I was close to obtaining few kg´s of the ones on my first pic. But manually, it is nowhere doable, and H2SO4/HNO3 in larger quantity does not make it particularly easy to scavenge silver, as Ag2SO4 precipitate.

No, I do not make videos on YouTube  once I wanted, but it was too time consuming and complicated for me


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## snoman701 (Mar 30, 2022)

orvi said:


> Very interesting video. I was close to obtaining few kg´s of the ones on my first pic. But manually, it is nowhere doable, and H2SO4/HNO3 in larger quantity does not make it particularly easy to scavenge silver, as Ag2SO4 precipitate.
> 
> No, I do not make videos on YouTube  once I wanted, but it was too time consuming and complicated for me


I've never had a problem with Ag2SO4. I generally end up with ferric iron dropping out of nitric when the pH goes up, and the titration of just enough sulfuric acid to get it in to solution seems to do the trick. If I cement out silver, then add HCl to a supposedly barren solution that has been cemented, I will still get a precipitate which very well could be the silver complexing with sulfate....likely because I risk death by pouring my sulfuric acid into nitric acid and it's the concentrated sulfuric that creates problems. 

Either way, if you process your silver chloride using the iron / sulfuric method, then melt the washed silver with an iron stir bar, you don't lose any that I'm aware of.


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## orvi (Mar 31, 2022)

snoman701 said:


> I've never had a problem with Ag2SO4. I generally end up with ferric iron dropping out of nitric when the pH goes up, and the titration of just enough sulfuric acid to get it in to solution seems to do the trick. If I cement out silver, then add HCl to a supposedly barren solution that has been cemented, I will still get a precipitate which very well could be the silver complexing with sulfate....likely because I risk death by pouring my sulfuric acid into nitric acid and it's the concentrated sulfuric that creates problems.
> 
> Either way, if you process your silver chloride using the iron / sulfuric method, then melt the washed silver with an iron stir bar, you don't lose any that I'm aware of.


Yeah, that is the trick  now I can clearly see what I was doing wrong.
Definitely must try that "restricted sulfuric ammount" method.


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## Geo (Apr 16, 2022)

You could possibly mill them and use magnetic separation to remove the magnetic part?


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## Geo (Apr 16, 2022)

Ta is insoluble in nitric acid. Separation of the silver and Ta should be easy enough with nitric acid.


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## Ohiogoldfever (Apr 16, 2022)

I have a Porta Band (small metal cutting bandsaw) that I built a stand for. Makes opening something like this cake. A pair of pliers and a fine toothed blade. Probably 10-15 seconds a unit.

Very useful tool to have around in general.


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## orvi (Apr 17, 2022)

I tried many of the techniques what you guys suggested here. Cutting is a nightmare, acidic electrolyte mess up the saw (need frequent wiping), but it is relatively low-budget and works. 
As I do not have the mill, I cannot mill them to the small pieces and than magnetically separate the Fe. But I think this would be a way to go in bigger lots.
Sulfuric/nitric is very easy and relatively elegant method, but it spend quite a bit of nitric... And also can be quite violent when you add too much nitric, nothing happens, and then use a bit of sulfuric and beaker is like exploding 

Now I do not have this material in quantity. I was close to purchasing like few kg of these, but seller sell them somebody else...


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## Bator (Apr 17, 2022)

A proven method of field hiking that also has a right to life
Durable metal container with handles and cover. Make holes in the lid or leave a gap between the lid and the acid vapor outlet tank. Place the condensers in the tank and close the lid. The lid is securely attached to the container handles. Then we put it on the stove or on an open fire. When heated, the condensers break (the acid inside boils and breaks the condenser housing inside). After good warming up, cooling down, we get the rest of the cases and tantalum. You can recalculate the number and calculate the sound of the break, for reliability
Attention: The explosions are impressive, the thin wall of the pan can break through. It is not recommended to carry out this method in a residential building!
It is desirable to use a heavy container or fix or load the container from above, otherwise it will move under the influence of the explosion


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## macfixer01 (Apr 17, 2022)

Bator said:


> A proven method of field hiking that also has a right to life
> Durable metal container with handles and cover. Make holes in the lid or leave a gap between the lid and the acid vapor outlet tank. Place the condensers in the tank and close the lid. The lid is securely attached to the container handles. Then we put it on the stove or on an open fire. When heated, the condensers break (the acid inside boils and breaks the condenser housing inside). After good warming up, cooling down, we get the rest of the cases and tantalum. You can recalculate the number and calculate the sound of the break, for reliability
> Attention: The explosions are impressive, the thin wall of the pan can break through. It is not recommended to carry out this method in a residential building!




That sounds like a good method for removing the acid hazard anyway. At that point can they just be pried open the rest of the way? Or depending on what equipment you have available I guess you could saw them in half with a bandsaw or maybe cut them in half with just a heavy hammer and a chisel?


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## orvi (Apr 17, 2022)

Bator said:


> A proven method of field hiking that also has a right to life
> Durable metal container with handles and cover. Make holes in the lid or leave a gap between the lid and the acid vapor outlet tank. Place the condensers in the tank and close the lid. The lid is securely attached to the container handles. Then we put it on the stove or on an open fire. When heated, the condensers break (the acid inside boils and breaks the condenser housing inside). After good warming up, cooling down, we get the rest of the cases and tantalum. You can recalculate the number and calculate the sound of the break, for reliability
> Attention: The explosions are impressive, the thin wall of the pan can break through. It is not recommended to carry out this method in a residential building!
> It is desirable to use a heavy container or fix or load the container from above, otherwise it will move under the influence of the explosion


This is a very interesting approach, but as I do not know what type of electrolyte and what chemicals in the seals are used, I wouldn´t be prone to do this that way. Old stuff, old guys literally stuffed everything with azbestos and PCB´s, and this is the stuff I am not willing to heat and possibly disperse in my workplace.

Grinding sounds bit more safe, apparatus is easily washed with some acetone afterwards - if any organic junk was present, it will be conveniently washed and contained.


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