Provide process troubleshooting for reducing fouling in a metals electroplating process.
Process Engineering Associates, LLC (PROCESS) was contracted by the client, a metal plating and finishing manufacturer, to provide process engineering support to troubleshoot a carbonate reduction process at their US facility. PROCESS was asked to troubleshoot, diagnose, and recommend corrective steps to address current problems associated with an existing Cyanide Hydrolysis System and specifically, fouling of heat exchangers located directly upstream and downstream of the cyanide hydrolysis polishing reactor. The client was experiencing excessive fouling of the cyanide hydrolysis polishing reactor preheater and effluent exchangers.
A site visit was completed to obtain process data and take samples of the various process streams in the carbonate reduction system. PROCESS performed a literature search and review of the various cyanide destruction technologies and chemistries available to understand best practices and the proper operating envelope for the current system. Liquid sample data was used to generate and validate an OLI electrolytes simulation model for the carbonate reduction process. Once the model was fit to the existing process performance, various process modifications were evaluated for reduction in exchanger fouling including sodium borohydride addition, HCN/CO2 stripping, and acid addition.
PROCESS was able to determine that exchanger fouling was directly related to cyanide content. As cyanide content is reduced, metal cyanide complexes begin to precipitate as metal hydroxides, resulting in exchanger fouling. PROCESS made recommendations to increase the conversion of cyanide to cyanate upstream of the polishing reactor preheater and filter out precipitated solids prior to the exchanger. PROCESS also recommended that the client monitor their operation to stay within a recommended operating envelope with regard to temperature, pH, cyanide concentration, and metals concentration targets. PROCESS also recommended to further study their existing filter so as to improve filter efficiency and reliability.
- Process troublshooting
- Tuned process simulation development
- Process evaluation and improvement.