Perhaps a silly question regarding silver recovery

Steve Goldstein · Nov 23, 2020

I generate 2 liters of used fixer every 6 weeks or so. I've had bad luck with the electrolytic units - two times they've sulfided in storage between uses and no longer work - so I want to try the steel wool method. Can I use stainless steel wool for this purpose?

My aim isn't to get rich, but to keep the silver out of the waste stream. If, in 10 year's time, I have a tiny blob of silver to show for it, well that's just nice.

Nodda Duma · Nov 23, 2020

Steve I think it needs to be steel. Using Stainless would just be less efficient.

koraks · Nov 23, 2020

Steve Goldstein said:
Can I use stainless steel wool for this purpose?

It'll work, but it'll take loooooong before the process gets going. Better use normal steel/iron or tinfoil (i.e. aluminum).

removed account4 · Nov 23, 2020

I'd get a rack of steel wool. the byproduct would just be rust going into your waste stream.

Steve Goldstein · Nov 23, 2020

Should I always keep the steel wool covered in liquid or is it ok to let it dry out in between uses? I generate 2 liters of fixer every so often, and am wondering if it's better to decant the liquid after a few days and store the thing (mostly) dry or keep the wool covered. I have visions of steel wool simply turning to rust. Will it still work if that happens?

Ian Grant · Nov 23, 2020

Nodda Duma said:
Steve I think it needs to be steel. Using Stainless would just be less efficient.

Correct, commercial units use a high grade steel wool but not stainless, ordinary wire wool works but rots away quickly.

If you want to just drop the silver out of solution the cheapest wire wool you can find is the best. If the fixer's being filtered through a tailing unit then it must be steel wool. Tailing filters are typically used after a plating unit to remove the last Silver to a level of 2ppm or lower which is the maximum commercial level permitted for discharge into a drain in most countries. Holland & I think Germany have tighter restrictions.

Ian

koraks · Nov 23, 2020

Steve Goldstein said:
I have visions of steel wool simply turning to rust.

That tends to happen, yes. It will actually dissolve in spent fixer, andwhen taken out, it'll rust like crazy. I have a feeling you're perhaps forgetting that this is really a consumable - it has a very limited lifetime. It will last a few rounds, but you'll get to the point where you want to chuck it out when it's become too much of a sorry mess.
Don't overthink this though. Just get some steel wool scouring pads and get going.

Steve Goldstein · Nov 23, 2020

Off to the hardware store...

Ulrich Drolshagen · Nov 23, 2020

I use sodium dithionite for that matter. One table spoon full per litre of used fixer. Let it react in an open canister far away in your backyard for some days. It smells ugly. The silver (and the remains of the dithionite) will fall to the bottom and you can easily filter the rest off and use it as fertilizer or flush it into the sewer.
The mthod had been discussed here some years ago IIRC.

Ulrich

Fluidphoto · Nov 23, 2020

If you're just going for quick and dirty, add table salt to the used fix and give it a shake and then let it sit. The sodium displaces the silver and forms a white precipitate which settles to the bottom that you can then filter out with a coffee filter. Dry it out and set it aside. When I did this as a project in my chemistry class in highschool (30+ years ago), there was very little silver left in the remaining liquid and easily disposed of.

eli griggs · Nov 23, 2020

What about using a highly magnetic steel vessel, and simply plate the silver to that, to broken up off the surface, if it ever gets thick enough to be recovered?

Also, wash out the steel wool with Dawn dish detergent, so you're no putting oil into the mix, and the Wool breakes down / exchanges ions faster.

Cheers.

jay moussy · Nov 23, 2020

I lost track here, once the silver binds to the steel wool, where do remaining liquid(?) and now loaded steel wool go?

Hazmat day in your town for both?

Doremus Scudder · Nov 23, 2020

If there's a traditional photofinishing lab in your area, you might be able to arrange with them to take your used fixer for reclamation. They'd likely be happy to get the silver.

That's what I do.

Doremus

PhilBurton · Nov 23, 2020

koraks said:
It'll work, but it'll take loooooong before the process gets going. Better use normal steel/iron or tinfoil (i.e. aluminum).

Do you mean I can just toss a piece of aluminum foil into a container full of used fixer, and just wait until the silver gets recovered? In what form? How is it separate out from the fixer?

koraks · Nov 24, 2020

Yes, it works. The silver will precipitate as a dark powder. You can decant the liquid and then allow the sludge to dry.

jay moussy said:
once the silver binds to the steel wool,

It doesn't. It's ion exchange; the iron goes into solution and the silver drops out of it.

grat · Nov 24, 2020

koraks said:
It doesn't. It's ion exchange; the iron goes into solution and the silver drops out of it.

As my chemistry teacher was fond of saying... "If you're not part of the solution... you're part of the precipitate".

removed account4 · Nov 24, 2020

http://selftution.com/reactivity-series-of-metals-and-nonmetals/
lead, zinc tin, chromium. iron. .. to list a few of the moderate ones

PhilBurton · Nov 24, 2020

koraks said:
Yes, it works. The silver will precipitate as a dark powder. You can decant the liquid and then allow the sludge to dry.

It doesn't. It's ion exchange; the iron goes into solution and the silver drops out of it.

Do you need to filter the liquid as you pour it off, or does the sludge all drop to the bottom of the container?

koraks · Nov 25, 2020

Filtering is a good idea. The sludge will sink to the bottom, but it takes quite some time and a bit will still float around after a week or two. Best leave the jug alone as long as you can.

kevs · Nov 25, 2020

I've found after leaving spent fixer in a bottle for a few months, silver metal will plate out onto the inner surfaces. This happens with both glass and plastic bottles but I don't know why. The silver deposit can be dislodged by shaking the bottle, and collected by decanting off the liquid and washing the silver. I've collected almost a 35mm film container of silver powder this way over the past decade or so. It's a slow process, probably too slow to be of benefit to the OP but maybe useful for occasional, low-volume users like me.

I'll never get rich that way but it keeps the silver out of the waste stream.

Perhaps a silly question regarding silver recovery

Steve Goldstein

Nodda Duma

koraks

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removed account4

Steve Goldstein

Ian Grant

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Steve Goldstein

Ulrich Drolshagen

Fluidphoto

eli griggs

jay moussy

Doremus Scudder

PhilBurton

koraks

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grat

removed account4

PhilBurton

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kevs

Perhaps a silly question regarding silver recovery

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