Recovery of Zinc from Municipal Solid Waste Incineration Fly Ash

Abstract

In recent years, over one million tons of Municipal Solid Waste (MSW) incineration fly ash has been generated annually Taiwan. Only a small percentage of the ash was used as raw material for other utilities besides landfill. Fly ash contains many harmful heavy metals, such as Cd and Cr, among others; however, fly ash also contains many valuable metals, including as Zn, Pb, and Ga.To recover Zn from fly ash, in this work, an experiment was first designed to determine the physical and chemical properties of the fly ash. Then, treatment processes, including water leaching, acid leaching, and ion exchange were conducted.Test samples were subjected to scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence spectrometer (XRF), and atomic absorption spectroscopy (AAS) to determine their physical and chemical properties. Then, water leaching was conducted under optimal experimental conditions. Thereafter, acid leaching was performed using two different acids (hydrochloric and sulfuric) to extract the target metal ions, and finally the ion exchange process was deployed to concentrate and recover the target metal ions.Ultimately, an optimal process to recover zinc from MSW incineration fly ash was developed in this work. An aqueous solution containing approximately 1 wt% zinc was obtained by leaching with sulfuric acid. Zn was then concentrated using a chelating resin IRC-747 in column mode.