Copper recovery from treatment of simulated copper-iron wastewater using fluidized-bed homogeneous crystallization technology

Abstract

Electroless plating wastewater contains highly soluble Cu-EDTA complex which poses challenges for copper recovery using conventional methods. These complexes are destroyed first using Fenton process producing treated solutions with iron concentrations that may interfere copper recovery. The purpose of this study was to confirm the influence of trace amount of iron on copper removal, crystallization, and copper salt recovery using fluidized-bed homogeneous crystallization (FBHC) process. By varying several parameters like pH, initial copper and iron concentrations, and metal and precipitant inlet flowrate and molar ratio, the optimized conditions include pHe of 6.5–7.0, inlet flowrate of 15 mL min−1, and MR of 1.5. The effects of variable copper (3.15–9.44 mM) and iron concentrations (0.36–1.08 mM) were examined. The addition of iron had no significant impact on copper removal mainly due to its minimal presence in the solution, but a trend of decreasing, then increasing, copper crystallization ratio was observed at higher iron concentrations. The study recorded copper removal and crystallization rates from 88% to 96% and 75% to 95%, respectively, with varying iron concentrations. Characterization analyses of precipitates confirmed predominant presence of malachite and azurite. The FBHC's ability to obtain high purity spheroidal solid salts enables resource recovery and catalyzes strategies for circular economy practices.