Silver extraction from photographic fixer

A. Last I heard, the former owner or manager of Film Recovery Systems in Chicago was serving a life term for first degree murder because an employees died while recovering silver from X-ray film.

The point being that until you've had training in the safe operation of a silver recovery operation, I don't think you should attempt it.

A. The basic issue there was cyanide-based chemistry. Cyanide is a poison as a liquid, of course, but more importantly it releases deadly hydrogen cyanide gas if accidentally acidified. It needs special care. Regards,

A. You will find that companies, like mine, contract out silver reclamation services in order to avoid problems with employee exposures and related liabilities. We use Safety-Kleen's recovery service and we are currently evaluating a larger (10 gallons fixer per day) recovery unit. These devices are self-contained and due an excellent job of recovering silver from fixer for a nominal cost to us. Industry, of course, needs to invest in these devices in order to comply with wastewater discharge limits.

A. Slow down, pals! No cyanide has been used in photographic fixing or (colour) bleach-fixing solutions for decades. I have been doing silver recovery in Finland for 21 years and only read of cyanide in photography in history books.

What you need is a simple carbon plate from a large dry battery for an anode (graphite would be better, but maybe more difficult to find), a stainless steel sheet for cathode, and a voltage of 2 to 5 volts depending on electrode distance. Stirring of the solution helps. You will get ca. 90 to 98 per cent pure silver on cathode. The longer you continue this, the blacker and more dirty silver you get. Normally the end-point is around 100 mg/liter of silver, after that you will get silver sulfide sludge.

Bleach-fixing solutions need higher voltage and more than 500 mg/liter silver will probably stay in the solution. The chemical hazards include formation of hydrogen sulfide on high current density, or ammonia, if you mixed fixer with developer. This method will still leave too much silver in the solution so that you cannot discard the remaining solution into sewer.

A. You are correct. The dude in jail was recovering silver from negatives and the film. The picture that I say of the shop, it was a true slop shop.

There are silver recovery devices sold that are really mini plating cells. For industry, these are cost effective because of quantity and the dollars to afford the proper disposal of the residue from the fixer recovery.

At what silver is worth today, you will spend about as much as you will get for the silver. When you take it off site, as in home, you are technically guilty of operating a waste disposal site. Fine is up to 25,000 per day per violation.

All it takes is the wrong person talking somewhere and the badges will show up. They take a very dim view of it.

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I apologize for the confusion. Silver can be recovered from fixing solutions without cyanide; Film Recovery Systems was recovering silver from the X-Ray film itself rather than from fixing solutions.

But I still feel that safety training should be hands-on, not just pieces of this and that gleaned from the internet.

Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
2001

A. As a student, you may want to know what is done chemically, of course, Ganyfer. And if wish to take the time to review one of the longest threads on finishing.com, there are some answers in letter 15559.

But another thing a student may wish to learn is that, just as most factories don't make their own pencils or build their own forklifts, most modern factories avoid certain types of chemical treatment and instead send the wastes to specialists as Mr. Alexander noted earlier in the thread. Good luck,