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  1. #1
    Jon King's Avatar
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    Silver recovery from initial albumen wash

    Albumen prints are printed with an excess of silver nitrate, which is rinsed off in an initial wash before toning or fixing. I live in a house with a septic system, and while developer and stop bath end up in the system, I keep my used fixer in a 5 gallon container and take it to a local 1hr photo store when full to run through their silver recovery system.

    My question is: Does anyone have experience with silver recovery systems extracting silver from a silver nitrate solution? If so, does it work as effectively as it does with used fixer?
    Jonathan
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  2. #2
    David A. Goldfarb's Avatar
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    I haven't tried recovering this silver, but I have discovered that a wash where you fill a tray, shuffle the prints and soak for a few minutes, dump, and repeat about seven times is at least as effective, and in my experience more effective, than a running water wash in a wash tray and it uses a lot less water (essentially the method that Ansel Adams describes for washing prints during a water shortage, but using one tray instead of seven, because I don't have room for that many trays). If you were trying to recover silver, it would give you less effluent to deal with.
    flickr--http://www.flickr.com/photos/davidagoldfarb/
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  3. #3
    patrickjames's Avatar
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    David, I think he is more concerned about the silver ruining the septic system.

    The silver should be taken out in the recovery unit, but if it isn't at least it won't be in your septic system. (I know this sounds bad).

    Patrick

  4. #4
    Ole
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    I tried it out of curiosity...

    The first wash I did with very little water in a tray, sloshing it around until it got really milky. Dumped the water in an empty jam jar, and repeated the wash with fresh water. The third time there was little milkyness, so I went to running water.

    In the meantime I had aquired about a liter of very milky wash-water. I plonked a piece of copper in it to see what happened: Not much. Deciding it needed a little solvent, I added a teaspoon of sodium thiosulfate. The solution turned clear, and the copper piece was rapidly transformed into a small heap of porous silver.

    So yes, it can be recovered - and there's quite a lot of it.
    -- Ole Tjugen, Luddite Elitist
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  5. #5
    Ian Grant's Avatar
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    Jon, I worked in precious metal recovery for about 20 years and it is extremely easy and cheap to recover your excess silver.

    We used to sell small steel wool cartridges which were used after silver recovery / plating units in X-ray departments, but in our factory we made up our own systems.

    In your case as its small quantities use wire wool, usually sold in a hardware stores, filter the spent solutions through this wool the iron goes into solution and the silver plates out in its place. This works extremely efectively and is very cheap. Just save the residual wire wool until there's enough to warrant refining.

    Ian

  6. #6
    Jon King's Avatar
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    It seems that a combination of all the answers can work pretty well. Minimizing the volume of water to work with will help, and then adding hypo to turn the wash water into used fixer with some extra nitrate ions would get me to where it can be recovered. Probably just dumping the water in with my used fixer would work too. Then recover my own, or keep going to the one hour photo guy.

    Thanks for the help. My last chemistry course was in 1980, so things are quite rusty in that corner of my brain!

    This problem was my last barrier to processing albumen prints at home, so I'm off to crack some eggs (ok.. open up a can of Deb-El egg whties, lol)
    Jonathan
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  7. #7

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    There are a few types of silver recovery systems but they vary in terms of how thoroughly they can remove silver from the solution.

    The metal cartridge system ("steel wool system") varies hugely in terms of its treatment efficacy. If used in exhausted fixer and given sufficiently long reaction time, they may do a reasonable job but many units fail to meet the regulatory standard of residual silver level. Also, this type of system is terrible in removing silver from wash water or forms other than exhausted fixer, due to corrosion of the steel preventing plating of silver. (In exhausted fixer, very high concentration of thiosulfate acts as a corrosion inhibitor.)

    In terms of efficacy of treatment and thoroughness of silver removal, electrolytic system is simplest and most economical.

    There are a few chemical ways to remove silver from fixer or wash water. The chemical treatment part is fairly simple and they convert the soluble silver compounds to insoluble silver compounds in sludge form. However, the individual particle of the sludge formed in this way is extremely fine and they go right through most filters. That is, it is difficult to separate the solid silver from the rest of the solution, and this system is not widely used in practice.



 

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