Quantitative Mineral Phase Analysis for Reliable Waste Metal Stabilization and Recovery

Abstract

The ability of designing marketable products derived from waste to simultaneously prevent the environmental pollution and recover valuable material resources is a major technological challenge in the 21st century. Conventional inorganic product designs are often assisted by X-ray diffraction (XRD) technique to qualitatively identify the mineral phase types in the products. However, a further advancement in the quantitative capability of XRD technique is now available to further accurately control product quality. In this study, we will demonstrate the successful applications of the state-of-the-art quantitative X-ray diffraction (QXRD) on stabilizing the hazardous metals in ceramic products and on extracting metallic lead from waste electronics. The feasibility of stabilizing metal-laden waste sludge and ash materials by a wide variety of aluminum- and iron-rich ceramic precursors will be demonstrated by the high metal transformation efficiency and the significant reduction of intrinsic metal leachability. Our work of recovering metallic lead from waste cathode ray tube (CRT) glass will also reflect how the QXRD can assist the development of new resource recovery technologies. A method of reductively transforming the lead in CRT glass into its metallic form through the reactive sintering with zero-valent iron was invented and optimized by the QXRD technique. With the rapid progresses in materials science and characterization techniques, substantial new technological developments in the beneficial uses of waste materials are now spearheaded by the interdisciplinary environmental materials research.