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Process to extract silver from the waste fixer/hypo solution
2007
I am very seriously thinking about setting up a silver extraction unit with capacity of approx. 300 gms./day. I wish to have a clear picture about the following points.
- Enquiries
1) How much silver can really be extracted in terms of gms./lit. from an used fixer in saturated state ? And what can be the % of purity of this extracted silver ? At what price can it be sold at the current market price?
2) Can the fixer solution after extraction of silver be again reused for photographic development purpose? If so, at what price it can be sold to the consumer? Is there any qualitative difference with a "fresh"solution ?
3) What is really the difference between Fixer and Hypo? Would you please give me clear idea on that? I do not have any.
4)Can there be any quantitative difference in silver content in different used fixer/hypo solutions procured from different sources viz., one from photography unit, the other from X-ray clinic, still other from offset printing unit or CT scan clinic etc.?
5) Can the film scraps also be utilized for silver extraction purpose?
6) How much hazards are involved in this trade, from health point of view? What precautions are to be taken ?
I have come across a plant manufacturer who claims they can provide an automatic plant with a capacity of 300 gms/day or higher capacity, which requires no other input except used fixer and can produce 10 gms. of pure silver from one lit.of saturated fixer solution. What should be my checkpoints before deciding on it?
I am completely new in this field and practically I do not have any idea on it , though I am seriously interested to start it without much delay. So I would be highly grateful to get your valuable suggestions on this trade. With regards, Yours sincerely,
New Entrepreneur - Vadodara (Gujarat), INDIA
29-page booklet from Kodak, "Recovering Silver from Photographic Materials"
Hello, Maulik. Similar questions were asked hundreds of times on letter 15559 without great answers. We recently edited that letter to remove dozens of duplicate questions and cull it down because it didn't make sense for readers to have to wade through an endless stream of "I have the same question". When a question is on line for 10 years, read by tens of thousands of people, responded to by hundreds, and nobody is happy with the answers, I think it implies something. I infer that this process of recovering silver has been oversold as a road to riches and no one is ever happy with the real-world answers and experience because they don't validate the dream. But gain what you can from letter 15559. Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2007
2007
"2) Can the fixer solution after extraction of silver be again reused for photographic development purpose? If so, at what price it can be sold to the consumer? Is there any qualitative difference with a "fresh"solution ?"
That would depend on the extraction method used. Some extraction methods would "kill" the fixer solution, others would not. But generally, any Ag extraction method applied on fixing solutions will render the solution useless.
"3) What is really the difference between Fixer and Hypo? Would you please give me clear idea on that? I do not have any."
"Hypo" was the old, corrupted term for sodium thiosulphate [on
eBay or
Amazon]
, the main component used in photographic processing for dissolving undeveloped and unexposed silver halides. There are several types of Fixers used in photo processing. Those used for BW and Colour are formulated differently. Then there is also a 'bleach-fix' formula used for certain types of colour material processing. The type of make-up would be basis of the recovery method used.
"4)Can there be any quantitative difference in silver content in different used fixer/hypo solutions procured from different sources viz., one from photography unit, the other from X-ray clinic, still other from offset printing unit or CT scan clinic etc.?"
The type of material which ran through the fixer would determine how much of it is left. Xray plates have heavy silver coating weights and therefore would leave more in the fix solution. Fixers for Xray films also are more concentrated than fixers used for other forms of photo processing. Colour films in general would have more silver than BW camera films- colour films have three emulsion layers. Fixers are discarded once their silver content becomes saturated, at which point their ability to function as part of the process becomes ineffective.
5) Can the film scraps also be utilized for silver extraction purpose?
Yes. Unexposed film ends left in the spools would have some silver in them. Silver BW negs and prints (including paper prints) have silver in them too. But you'd have to have plenty of these to recover any significant amount. Colour negatives, movie prints, and paper prints DO NOT have silver in them- only dyes are left since all the silver in their emulsions are dissolved in the fixer during processing.
Jay
- Quezon City, Philippines
February 28, 2008
I have been in the recovery business for almost twenty years now and as far as we know, we were able to recover almost 90% of the total silver content of the fixer.
Unlike the negative films that we burn to get a reddish brown soot, are stored in a plastic drum (around 48 gallons) is mixed with sodium hydroxide (industrial lye) about I kilo and leave for 10 minutes after mixing. Add another kilo of sodium sulfide ( yellowish flake ) and mix well until black granules of smudge is visible. When the granules reach its peak amount, leave for 39 minutes and drain.
Large amount of smudge is left at the bottom of the tank or drum.
- Calamba City, Laguna, Philippines
Q. Dear Sir,
I want to know how much sodium sulphate & caustic soda
[affil links]
should be mixed in fixer hypo solution for extracting silver.
- Delhi, India
June 7, 2012
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