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Pollution Prevention and Control Technologies for Plating Operations
Section 5 - Substitute Technologies
5.5 CADMIUM USE REDUCTION/ELIMINATION
Cadmium, which is most often plated from a cyanide solution, was identified by the respondents of the Users Survey to be of significant concern. At the time of the survey, 30 percent of the respondents performed cadmium plating using a cyanide bath and 2 percent used a non-cyanide bath. Ten percent of all respondents indicated that they have compliance difficulty with cadmium. Seventeen percent indicated that they felt there was a technology transfer insufficiency with respect to cadmium and 8 percent indicated that there was a need for better cadmium alternatives or control technologies.
Based on the results of the Users Survey, it is obvious that cadmium-cyanide plating is much more difficult to substitute for than cyanide-based plating in general (see Exhibit 5-5). Only 8 of the respondents (or approximately 8% of the cadmium platers) have successfully made this substitution, with another 8 (or approximately 8% of the cadmium platers) indicating partial success. Another 3 respondents (or approximately 3% of the cadmium platers) have successfully implemented a low-cyanide, low-cadmium substitute. No single cadmium substitute stood out as the most successful, with tin and tin alloys, zinc (non-cyanide), cobalt-zinc and zinc-iron being used. The primary problems with cadmium substitutes were: (1) customer acceptance; (2) the quality of the finish; and (3) their higher cost.
In addition to the plating shops that indicated they have substituted non-cadmium or low-cadmium processes for a conventional cadmium process, there were ten shops that indicated they have eliminated cadmium plating in order to meet environmental regulations.