Characteristics of MSWI fly ash during vitrification

TIAN Shu-lei^1,2, WANG Qi³, WANG Qun-hui¹, MA Hong-zhi¹

1.Dept.of Environmental Science and Technology, Harbin Institute of Technology, Harbin 150090, China;2.Dept. of Environmental Science and Engineering, Tsinghua University, Beijing 100084,China;3.Chinese Research Academy of Environmental Science,Beijing 100012,China



Abstract:

The vitrification characteristics of municipal solid waste incinerator (MSWI) fly ash were investigated. Effects of temperature on the binding efficiency of heavy metals, the change of chemical compositions and the weight loss of fly ash in the range of 800-1350 ¡æ were studied. Toxicity Characteristic Leaching Procedure (TCLP) of the United States was used to analyze the leaching characteristics of heavy metals in fly ash and molten slag. Results indicate that chemical compositions, the weight loss of fly ash and the binding efficiency of heavy metals in fly ash have a tremendous change in the range of 1150-1260 ¡æ. The percentage of CaO, SiO2 and Al2O3 increases with the increasing temperature, whereas it is contrary for SO3, K2O, Na2O and Cl; especially when the temperature is 1260 ¡æ, the percentage of these four elements decreases sharply from 43.72% to 0.71%. The weight loss occurs obviously in the range of 1150-1260 ¡æ. Heavy metals of Pb and Cd are almost vaporized above 1000 ¡æ. Cr is not volatile and its binding efficiency can reach 100% below 1000 ¡æ. Results of TCLP indicate that the heavy metal content of molten slag is beyond stipulated limit values.

Key words:  heavy metal  SWI fly ash  eaching concentration

DOI£º10.11916/j.issn.1005-9113.2009.01.022

Clc Number:X705

Fund: