Thermal Conversion of Hazardous Metal Copper via the Preparation of CuAl2O4 Spinel-based Ceramic Membrane for Potential Stabilization of Simulated Copper-Rich Waste

Abstract

In this study, a new idea to immobilize hazardous CuO as simulated Cu-rich waste via the reutilization of abundant bauxite minerals was demonstrated by thermally converting it into the stable spinel structure to prepare functional porous ceramic membranes. With the addition of aluminum-rich bauxite mineral, over 90% conversion of CuAl2O4 spinel structure was achieved at the 1000–1100 °C sintering window. Higher sintering temperatures would destabilize the CuAl2O4 structure, leading to the formation of minor precipitates such as Al2O3 and CuO phases. Furthermore, addition of calcined bauxite would induce more minor precipitates than the natural bauxite did. This was likely attributed to the fact that the evaporation–condensation reaction of CuO was significant on large calcined bauxite particles. Following leaching experiments clearly indicated that these copper ions were securely associated in the stable CuAl2O4 spinel structure, and no significant amount of copper ion leaching was found even in acidic so...