Production of Synthetic Stone From Municipal Solid Waste Incineration Fly Ash.
Date Issued
2006
Date
2006
Author(s)
Chou, Fu-Yuan
DOI
zh-TW
Abstract
The utilization of municipal solid waste incinerator fly ash has to overcome the problems of high contents of chlorides and leaching of heavy metals. The feasibility of producing artificial aggregates from fly ash by a combined washing and sintering process, in which most alkali chlorides could be removed and heavy metals could be immobilized, has been studied. Fly ash, collected at the air pollution control units, was washed with deionized water, NaOH solutions (1-10 wt.%), and H3PO4 solutions (1-10wt.%), respectively, with a liquid/ solid weight ratio of 7. The dry washed samples were then pelletized with a pressure of 5000 psi. and were sintered at 900 ℃ and 1000 ℃ for 1 hour.
The chlorine content of fly ash was markedly reduced after washing. Leaching tests of fly ash treated by the combined process showed that the amounts of heavy metals dissolved were less than the standard values set for the hazardous industrial wastes in Taiwan, only for fly ash washed with deionized water or with phosphorous acid solutions. However, the immobilization of heavy metals was more pronounced in the later case. In that case, heavy metal ions were immobilized in the matrix of calcium phosphate gel, and subsequently were stabilized in the sintered cylinders. The compressive strengths of sintered cylinders were greater for fly ash washed with phosphorous acid solutions. When 5 wt% and 10 wt% phosphorous acid solutions were used, the sintered cylinders did not disintegrate for a long period of exposure in ambient air; their compressive strengths (112~305 kgf/cm3) and values of Vickers hardness (1.65~5.37GPa) were comparable to that of bricks and marble. Fly ash treated by washing with phosphorous acid solutions and subsequent sintering may be considered suitable to use as a constructive material.
Subjects
石材化
飛灰
Synthetic Stone
Fly Ash
Type
thesis
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