Energy Effective Contaminant Removal from Closed Loop Recovery Systems for Cyanide Based Electroplating

摘要

An ultra-low-temperature heat pump evaporator was developed to provide a feasible alternative to conventional chemical treatment and sludge disposal of heat sensitive cyanide based electroplating wastes. The evaporator system, trademarked Fridgevap, was successfully tested on a cadmium cyanide plating line, proving the feasibility of recovering and returning the plating solution to the bath. The purpose of the project reported here was to develop and test an auxiliary crystallizer to continuously precipitate sodium carbonate decahydrate (washing soda) contaminants, thereby enhancing the effectiveness of materials recovery. The combined evaporator and crystallizer system underwent limited testing on both a cadmium and a zinc cyanide plating line. This report describes and discusses the development and testing of the prototype closed loop recovery system and the patented heat exchanger which made the system possible. Included is a comparison with conventional chemical precipitation and sludge disposal. (ERA citation 12:025129)