Tinker Air Force Base - Oklahoma City, OK
Although cadmium plating has been eliminated in the Oklahoma City-Air Logistics Center (OC-ALC) plating shop, there are still a great number of parts that must have old cadmium coatings removed. This process results in large amounts of cadmium contaminated strip solutions. To reduce this waste stream, a system was developed to rejuvenate the stripping solutions for reuse by selectively removing cadmium.
The cadmium strip rejuvenation process uses an ion exchange column to selectively remove cadmium from contaminated strip solutions. A specially designed resin was developed that removes cadmium from the solution. When the resin can no longer remove cadmium, it can be rejuvenated with ammonia. The cadmium is then electrowinned (plated) from the ammonia solution. This pure cadmium can then be sold.
This process allows the plating shop to reuse the stripping solution several times before disposal. When disposal is finally necessary, the solution will contain only trace amounts of cadmium making it less expensive to dispose. Finally by plating the cadmium out of the ammonia regeneration solution, the cadmium can be sold as a pure metal instead of disposed of as hazardous waste.