Fly ash from municipal solid waste incinerators (MSWI) consists of various substances, including a lot of heavy metals. In cases where fly ash contains a lot of chlorides, it is very difficult to apply general treatment methods because chlorides could hinder hydration in cementation and cause great loss in vitrification. In this study, we report a promising method for the treatment of fly ash containing a high concentration of chlorides. A colloidal silica solution was induced to stabilize the fly ash. The fly ash used in this research has a chlorine level over 35 wt.% as well as containing heavy metals, such as Pb (1120 ppm) and Zn (5430 ppm). The samples were prepared at a temperature of 600-800 degrees C for 2h after mixing with the fly ash and a 4 wt.% colloidal silica solution. The effect of the colloidal silica was evaluated by the leaching test, Toxicity Characteristic Leaching Procedure (TCLP). The solidified products with fly ash and colloidal silica at temperatures of more than 700 degrees C had an excellent resistance, with Pb(2+) <0.02 ppm, Zn(2+) <0.52 ppm, and Cd(2+), Cr(2+), Cu(2+), Mn(2+) <0.01 ppm, and it could be influenced by the phases containing Ca and Si formed above 600 degrees C and reduction of a chemically weak phase.
[1]
V. Laperche,et al.
Chemical and Mineralogical Characterizations of Pb in a Contaminated Soil: Reactions with Synthetic Apatite
,
1996
.
[2]
Jong Heo,et al.
Solidification and recycling of incinerator bottom ash through the addition of colloidal silica (SiO2) solution.
,
2007,
Waste management.
[3]
R. J. Hunter,et al.
Introduction To Modern Colloid Science
,
1993
.
[4]
Jong Heo,et al.
Vitrification of fly ash from municipal solid waste incinerator.
,
2002,
Journal of hazardous materials.
[5]
J. A. Ryan,et al.
In situ lead immobilization by apatite
,
1993
.
[6]
J. Heo,et al.
Soil Remediation Effects of a Na2O–P2O5 Binary Phosphate Glass on Pb-contaminated Soils
,
1998
.
[7]
Wei Sun,et al.
Hydration of high-volume fly ash cement pastes
,
2000
.
[8]
R. D. Rawlings,et al.
Development of a new glass–ceramic by means of controlled vitrification and crystallisation of inorganic wastes from urban incineration
,
1999
.
[9]
A. Karamanov,et al.
Structure, chemical durability and crystallization behavior of incinerator-based glassy systems
,
2008
.