ELECTROCHEMICAL DESTRUCTION OF COMPLEX CYANIDE

Abstract

A batch electrochemical cell consisting of a pair of stainless steel wire-mesh electrode was used to electrochemically decompose concentrated cuprous cyanide waste solution. The concentrations of free, complex, and total cyanide were measured as a function of electrolysis time for various cell currents. The total cyanide concentration in the waste solution was reduced from 1200 ppm to less than 50 ppm with an electric power consumption on the order of 14-34 kWH per kilogram of cyanide destroyed. Copper was recovered in its metallic form at the cathode and as CuO deposit at the anode with a combined recovery rate greater than 90%. In addition, cyanide complex was found to chemically decompose at the stainless steel meshes, rendering a coulombic efficiency greater than 100% in some of the experimental runs.