SUMMARY:Coal fly ash(CFA),which contains hazardous elements such as selenium and boron. These elements are easily leached out to water environment and contaminate the surface and groundwater. The leaching amount of these hazardous elements from CFAs exceeded the environmental standards of soil and landfill sometimes. In this study, effects of aging process on the leaching of hazardous elements from CFAs was examined. The leaching amount of selenium, boron, chromium and fluorine from CFAs

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... ed with the lapse of aging time. Selenium leaching from aged CFAs was influenced by the calcium content in original CFAs. The results of XRD analysis indicated selenium in aged CFAs was immobilized by hydrated minerals such as ettringite.