Study on Electric Arc Furnace Dust Solidified / Stabilized with Geopolymeric Material

• Main Authors: Yu-Hung Chu, 朱祐弘
• Other Authors: 柯明賢
• Format: Others
• Language: zh-TW
• Published: 2010
• Online Access: http://ndltd.ncl.edu.tw/handle/pywz45

碩士 === 國立臺北科技大學 === 環境工程與管理研究所 === 98 === As electric arc furnace dust is one of the hazardous waste containing heavy metals, resulting in huge amounts of electric arc furnace dust to be managed. The stabilization/solidification of the electric arc dust using geopolymerization technology is described in this study. It was utilized fly ash, metakaolinite, sodium silicate and alkaline solution to prepare electric arc furnace dust geopolymerized solidification/stabilization matrices (EAFDGPSSM) in this study. The effects of curing time, SiO2/Na2O ratio and SiO2/Al2O3 ratio on compressive strength, heavy metals leachability and micro-structure of EAFDGPSSM would be investigated. In addition, the long-term stability of heavy metals in EAFDGPSSM and the leaching behavior of EAFD and EAFDGPSSM would be also described. The results indicated that the compressive strength of EAFDGPSSM prepared with SiO2/Al2O3 and SiO2/Na2O ratio respectively 2.0 and 1.25 would be higher. The leaching concentration of Pb and Cd in EAFDGPSSM cured after 28 days by TCLP method was lower than TCLP requlatory procedure limits and it showed that EAFDGPSSM could effectively immobilize Pb and Cd in electric arc furnace dust. The XRD patterns showed that the diffraction peaks were mainly caused by ZnFe2O4, NaCl and Zn(OH)2 phases present in EAFDGPSSM. The spectra of FTIR indicated that the vibrational band at 962～1032 cm-1 was attributed to the Si-O-T (T=Si or Al) asymmetric stretching mode. The microstructures of EAFDGPSSM showed that the grain of EAFDGPSSM was compact. The semi-dynamic leaching test (SDLT) was conducted to evaluate the long-term stability of Pb in EAFDGPSSM respectively prepared with SiO2/Al2O3=2.49 and SiO2/Na2O=1.0, SiO2/Al2O3=2.0 and SiO2/Na2O=1.25 and cured after 28 days. The results carried out by SDLT showed that after 60 days extraction, the long-term stability of EAFDGPSSM prepared with SiO2/Al2O3=2.0 and SiO2/Na2O=1.25 would be better then EAFDGPSSM prepared with SiO2/Al2O3=2.49 and SiO2/Na2O=1.0. Moreover, the cumulative leaching percentage of Pb in EAFDGPSSM only reached to 51-66%. The microstructures of EAFDGPSSM showed that the grain of EAFDGPSSM would become porous after 60 days extraction. The spectra of FTIR indicated that as extraction time increased, the vibrational band of Si-O-T (T=Si or Al) asymmetric stretching mode would shift to higher wavenumbers. The pH-dependence leaching test was conducted to evaluate the leaching behavior of major elements and trace elements in EAFDGPSSM respectively prepared with SiO2/Al2O3=2.49 and SiO2/Na2O=1.0, SiO2/Al2O3=2.0 and SiO2/Na2O=1.25 and cured after 28 days.The results indicated that the leaching behavior of Si, Al , Ca, Pb, Zn and Cd was respectively controlled by solubility of Ca6Al2(SO4)3(OH)12．26H2O, CaSO4, CaCO3, PbO, Zn(OH)2, CdO and Cd(OH)2.