Thanks for the reply btw :)
i am not really sure ..
i am not a chemist, either ... and i am not
really sure how you would go about doing that ..
and i am not sure
if whatever you decide you would want to
change the ph with will do something adverse
with the recover devices ..
i will ask again, and let you know ...
i asked the manufacturers what they suggest ..
and they said it is beyond their scope of expertise ..
and i am sorry to say, it is beyond mine too ...
maybe a mini-lab who does recovery can let you know
what they do to lower the ph ...
sorry i can't be of more help ..
The issue with bleach & fixer or blix is the bleach will start to re-dissolve the silver already plated out.
It's getting late here (Turkey) so I'll re-read tomorrow. meanwhile John can you send me technical data on the units & I'll get back to you.
thanks for the updates, John.
Ian, is there a way to 'neutralize' the bleach so that it wouldnt redissolve the silver that's already been plated out? Would lowering the PH to 3 be enough to keep the potassium permanganate bleach from redissolving the silver? (I know those might be dumb questions, but my knowledge of chemistry is 'limited,' to say the least :) )
In large scale silver recovery silver is plated out of recirculating fixer or bleach fix (blix) using sophisticated plating units that control the ampage precisely, too much current and the fixer is destroyed.
On a smaller scale usually mixing the bleach fix (prints) with the fixer from films after colour processing and also the rinse/wash water is sufficient before passing the solutions through a device like the Silver Magnet units. This will remove most of the silver however the remainder should be removed by then passing the solutions through a Steel/Wire wool cartridge.
The Silver magnet should reduce the level of Silver to 10-15 ppm (very approx) with the cartridge as well to below 1ppm. With just a Silver Magnet then the spent solutions should be diluted by about 10 -20X to comply with the legal 1ppm discharge limits (most areas UK/EU/US).
Black & White processing:
With B&W fixer the Silver Magnet will work more efficiently even with undiluted fixer - which it's designed for.
It needs to be remembered that the small volumes used in home darkrooms are normally very heavily diluted by domestic water wastes and are of little or no concern to waste authorities, but you need to be aware of local regulations.
Kodak's guidelines for safe disposal of photo chemistry are based on agreed procedures accepted by virtually all authorities in North America and The EU/UK and are available online.
Lets say I do pour my bleach, which is potassium permanganate and sodium bisulfate, the clear bath (sodium metabisulfite), spent fixer, and wash water in the same container, the silver magnet would be able to retrieve the silver from that, right? Sorry if this sounds like a dumb question, but I think I've gotten myself confused trying to figure out how to get the ph to 3, as Jnanian said his magnet supplier suggested. BTW, I'm finding nothing worth mentioning about silver recovery on the internet. All I'm finding are MSDS sheets on potassium permanganate, patents for silver recovery systems, and some wikipedia entries for potassium permanganate and processing film :/
If you mix the permanganate solution with the metabisulphite the bleach is destroyed so you won't have problems passing that through the Silver Magnet especially if you mix with the fixer.
thanks for your help ian !
as ian suggests it is best not to dilute the spent fix with the wash water
you want as high a concentration of fix/silver for the magnet to work.
if you are looking into a trickle tank ( iron steel wool tanks ) it can scrub
the wash water, and the post-magnet spent fixer to get the rest of the silver from it.
used with the magnet, the trickle tanks can handle 1000 to 2000 gallons of waste
and are pretty efficient ... working alone, without the magnet to pre-de-silver your waste
the tanks can handle about 400-800 of waste ( depending on the size of the cartridge / tank )
I have one of these units and have always wondered...just when should I stop? Should the red LED be glowing brightly in a lit room, or glowing dimly in a dimly-lit room, or...?