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Fixer Management

Fixer management
Silver recovered from used fixer is a valuable resource. Your office can practice silver recovery by containing used fixer for off-site recycling or treating the fixer on-site with a silver recovery unit. The attached list identifies businesses providing both on- and off-site recovery services. Some recyclers may give you a refund or credit for the recovered silver. If your practice generates only small quantities of fixer, it may be more cost-effective and efficient to have the fixer transported off-site for silver removal. By opting for off-site disposal, you are guaranteed 100% recovery of silver in x-ray fixer. By using radiovisography imaging technology, you may be able to reduce or eliminate fixer use altogether.

Off-site disposal
Several local vendors offer fixer pick-up services. Some x-ray chemical vendors will transport used fixer to their facility, remove the silver and blend the spent fixer with new fixer for reuse. Other companies will transport used fixer to a centralized recovery facility for silver reclamation.

When storing fixer for off-site treatment or disposal, remember to:
1. Collect and store the fixer in a closed plastic container.
2. Label the container "Hazardous waste - used fixer" along with the date when fixer was first added to the container.
3. Keep records of the volume and frequency of off-site fixer disposal for a minimum of three years.

On-site treatment
You can purchase or lease a silver recovery unit to remove silver from spent fixer. Canister units are usually sufficient for removing silver from small volumes of fixer and can be used alone or in series. Electrolytic units also are available and can be followed by a canister to ensure as much silver as possible is recovered. Talk with a silver recovery service about what will work best for your practice.

After a specified interval, the canister or the plated silver is shipped to a metal reclaimer where the captured silver is recovered.

As a general guideline, the Silver Council, an industry trade group, recommends that a business producing less than 10 gallons of used fixer per week should have a recovery unit capable of removing at least 90 percent of silver from the fixer. The treated fixer can be discharged to the drain with permission from the city of Boulder Industrial Pretreatment program.

If your office uses a silver recovery unit, remember to:
1. Check the unit daily for leaks, spills and overflows.
2. Periodically check the flow rate of solution to the recovery system. typically a lower flow rate and a longer retention time will maximize silver recovery.
3. If using an electrolytic unit, check the appearance of the silver plate. The plate should be tan to brown and grainy. If it is black, mushy and smells like sulfur, the amperage may be too high. If the silver plate is hard and white, the amperage is probably too low. Consult your user’s guide for specific guidance.
4. Test the silver concentration of the treated fixer monthly. The test can be performed with an analytical test kit or a lab analysis. Periodic testing will tell you how effective your unit is at capturing silver and will alert you to recovery unit problems.
5. Record test results in a silver recovery log.