焚化爐飛灰之資源化研究

THE RECYCLING OF FLY ASH FROM INCINERATOR

卓志銘(Chih-Ming Chuo)

指導教授 ： 陳炎輝

大同大學/工程學院/化學工程學系所/碩士(2004年)

摘要

國內由事業機構所產生的含重金屬之有害廢棄物每年逾四十萬公噸，其中如焚化爐飛灰或電弧爐煉鋼業集塵灰，均可以新技術使其資源化。一方面順應國際上「零廢棄」的觀念以及資源永續利用的趨勢；二方面減少廢棄物之處理成本與二次污染的可能。都市垃圾焚化爐飛灰因含有較高重金屬量具有相當之危害潛勢，故依環保法規認定為有害廢棄物需加以妥善處理。本研究是在實驗室中尋求最適化學物質與重金屬形成化學鍵結的方式將焚化爐飛灰轉化以符合資源再利用之目的。
本研究係利用各種不同的化學物質添加於含重金屬之焚化爐飛灰中，並與重金屬形成化學鍵結，藉由化學物質添加量變化、不同養生天數及固化體積大小變化，找出穩定化及資源化之最佳條件，並以溶出試驗確定符合法規之要求。
由實驗結果可知，經化學鍵結劑穩定化後重金屬鍵結型態皆屬不易溶出之型態；而穩定化之最佳條件，以鉛為例: 化學物質添加量為3 %，處理後養生28天之TCLP溶出量為0.322 mg/l，已遠低於法規5 mg/l之要求。以XRD可鑑定出化學鍵結劑與重金屬及Ca形成穩定之金屬磷酸鹽類及磷礦石。飛灰加化學物質並加壓成型，養生7天後之抗壓強度可達到150 kgf/cm2，在本文也評估資源再利用的可行性。

關鍵字

焚化爐飛灰 ； 化學鍵結劑 ； 重金屬 ； 資源化

並列摘要

The total amount of heavy-metal containing hazardous industrial wastes could reach about 40000 tons annually in Taiwan. Some of the wastes such as fly ash form incinerator and EAF dusts from the electric arc furnace steel mills could be turn to re-use material with new technology to meet “zero waste” as international trend as sustainable concept in environmental protection; also, it may reduce the cost of treatment and secondary pollution during the traditional possible secondary pollution. Since the fly ash contains certain amount of heavy metals, hence, is classified as hazardous waste and need good treatment. This research is to find suitable chemicals and conditions to have the ash and EAF dust reacts and forming chemical bond in order to form the re-usable material that also meets the regulatory requirement.
The chemical bond formation is formed after different chemicals add to the waste in this research. With variation of different chemicals, different ratio of additions, different aging period, and the variation of volume reduction and mechanical performance, to find out the optimal conditions for better and more economical treatment.
From the results of various experiments, after chemically bonded heavy metals in the wastes, the solubility is reducing after treatment. The optimal condition is to add 3% of the chemical to fly ash, since the good formation of stable chemical bond of these heavy metals with chemical; it meets the TCLP standard after 28 days of aging process, for example, the dissolve quantity reduced to 0.322 mg/l of Pb. From the XRD study, the bonded heavy metals and calcium salts form a very stable phosphates and complex mineral material. Since the solubility product is very low, therefore, the dissolution is unlikely after treatment. This non-hazardous mineral can be further process in order to increase it mechanical strength; for example, it will reach 150 kgf/cm2 after pressurized process. This kind of material can be re-use with abide the environmental regulation as re-fill, base in road construction, seashore protection, and various application to replace the rock in civil applications.

並列關鍵字

chemical bond agent ； Fly ash ； heavy metals ； recycling

參考文獻

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