Plating silver out of developer solution.

[John Bush]

I know there are some chemistry buffs out there that will be able to help!!!

Current wastewater regs(state) restrict pouring X-ray developer solution down the drain. The offending component is the silver pulled of the unexposed portion of the film. The cost for the hazardous waste pick-up and processing is twice the cost of the developer solution. They process by plating the silver out, and I would like to do it myself. The savings would be in the pick-up/processing fee, not the silver collected.

I have a trickle charger and a 2-10 amp charger. I have a 15 gal. container, or a 5 gal. bucket to use. Which polarity for which electrode and what amp level should I use?? Thanks, John.

[David Epperson]

I always thought that they precipitated it out and then filtered the solids out of it.

[David G Baker]

John,
At one time I was part of a business that stripped the silver from unprocessed bank surveillance film (back before electronic imaging) and unprocessed x-ray film. Your best place to start on silver recovery is with your processing equipment, film and chemical suppliers.
I used 10 gallon rectangular fiberglass tanks that had carbon anodes fastened to two sides of the tank with photo grade stainless steel 1/4 inch bolts. I used a photo grade stainless steel drum that was turned by a Bodine gear head motor.
If I remember correctly electrons flow from negative to positive so the anode (the carbon) was the negative and the stainless steel drum was the positive. The electrons flowed through the fixer solution picking up the silver ions that have been put into solution by the photo fixer.
If you are really serious about reclaiming the silver you should really think about contacting a silver recovery service, they will recover the silver for you, supply you with the necessary equipment at no cost.
The goal of film manufacturers for years has been to cut back the amount of silver used on their films. I have not kept up with the industry for many years so I do not know if they have succeeded.
After the fixer has been stripped of most of the silver, the fixer solution is slowly filtered through a 5 gallon bucket that contains steel wool and down the drain. These buckets were purchased from Eastman Kodak Company.
Rotex was the brand name on some of my commercial recovery units.
Do a Google on NORTHWEST PACIFIC RECOVERY INC or Google silver recovery equipment.

[Charles Wiggins]

"Recovering Silver from Fixer Solutions and Rinse Waters
The most commonly used technology for recovering silver from fixer solutions and rinse waters is chemical recovery, also known as metallic replacement or metal displacement. This technology uses equipment commonly referred to as Chemical Recovery Cartridges (CRC), Metal Replacement Cartridges (MRC), or Passive Silver Cells (PSC). This technology is simple in principle and operation. In most chemical recovery systems, a cartridge or canister filled with steel wool or iron particles is connected to the fixer or rinse bath overflow and the excess solution flows through the unit under gravity. The silver thiosulfate complexes from the solution react with the iron in the steel wool. The iron goes into solution and the silver precipitates with the iron and settles to the bottom of the unit as a sludge. Treated solutions should not be recirculated through these cartridges, but rather should pass through at a slow rate for optimum silver recovery. When used properly, these units can reduce silver concentrations to below 1 ppm in the effluent at a low cost. To confirm that a selected silver recovery option is achieving the required discharge limits, it is important to periodically test the effluent being discharged. Test papers or test kits are available for this purpose, in addition to confirmatory laboratory analysis.
Silver recovery units require no electricity or special plumbing connections. The units take up little space and are readily available at minimal cost. The units must be replaced regularly as the iron is consumed. Two units are commonly used in series, with the second unit being placed in the lead position when a new unit is installed in the second position. The size of the unit must be matched with the volume and silver concentration of the fixer and/or rinse solution to optimize the amount of time the solution is in contact with the steel wool. These units are designed to be packaged and shipped directly to a silver reclaimer when spent.
Other frequently used technologies for silver recovery include chemical precipitation and electrolytic methods, also available from the DRMS."

http://www.p2pays.org/ref%5C07/06010.htm#recovering