Exploring The Potential of Spinels Stabilization for Hazardous Metals

High incorporation efficiency for hazardous nickel and copper were achieved via spinels (AB2O4) formation through the sintering with aluminum-rich and iron-rich raw materials commonly used in construction ceramics. With the understandings derived from high temperature crystal chemistry, the potential of beneficial use of waste sludge, fly ash, and slag to stabilize waste divalent metal ions for value-added products will be discussed. Quantitatively X-ray diffraction analysis was applied to reveal metal incorporation mechanisms and efficiencies. Results of prolonged leach tests in acidic environments prove the superiority of metal immobilization by spinels comparing to other product phases, although with small variation among different spinel phases. While current cement solidification/stabilization technologies are not generally successful in preventing metal mobilization in acidic environments, this study has developed a promising strategy of blending different types of waste solids to trigger a preferred incorporation mechanism for more effective metal stabilization and a variety of marketable products