鹽基度與冷卻速度對飛灰熱熔熔渣特性之影響

Effects of basicity and cooling rate on the characteristics of flyash-molten slags

林其巖(Chi-Yan Lin)

指導教授 ： 黃國林

國立屏東科技大學/工學院/環境工程與科學系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00184

摘要

摘要
台灣地區垃圾焚化爐產生的飛灰常以固化方式處理，其有害重金屬的含量往往偏高且屬於有害廢棄物，而這類飛灰常以固化方式處理，惟其固化物的長期安定性及掩埋普遍受到關心。垃圾焚化爐飛灰，亦可以熱熔處理形成熔渣予以安定化，而此熱熔程序的效果受到一些重要參數影響。本研究探討兩個重要參數。冷卻速率及鹽基度對熔渣特性之影響，並以X光繞射分析測其結晶構造、電子顯微鏡觀察其表面、TCLP試驗與酸蝕試驗測其金屬溶出特性。結果顯示同時添加SiO2及水淬的情況下，熔渣的玻璃化特性較為明顯，當鹽基度大於0.990時，無論冷卻方式為何，其非結晶相比例無明顯變化；而當鹽基度小於0.674時，水淬則顯著提高非結晶相比例達80～90%，並可有效包匣重金屬於矽酸鹽的網狀結構中，抑制重金屬之溶出。當以氣冷形成熔渣時，欲形成玻璃化結構，則需要更低之鹽基度(<0.511)。整體而言，由SEM、XRD與TCLP溶出結果顯示，玻璃狀結構對酸之抗蝕能力優於結晶狀結構。

關鍵字：熔融、飛灰、重金屬、鹽基度、非結晶相。

關鍵字

熔融 ； 飛灰 ； 重金屬 ； 鹽基度 ； 非結晶相

並列摘要

Abstract
In Taiwan, the fly ashes from municipal solid waste (MSW) incinerators have high toxic metal contents and they are usually regarded as hazardous wastes; furthermore, the hazardous fly ashes are commonly treated by solidification with concerns of long-term stability for landfill disposal. The fly ashes can also be treated by melting and the metals in flyash-molten slags can be stabilized. Some important parameters affect the properties and metal stability of slags obtained from melting processes. The study investigated effects of basicity and cooling rate on the characteristics of flyash-molten slags. The crystal structures and surface morphology of slags were examined using x-ray diffractometry (XRD) and scanning electron microscopy (SEM), respectively. TCLP and acid etching tests were performed to characterize the metal leaching.
When SiO2 was added and water-quenching was used, the slags exhibited obvious glassy structure. When the basicity was higher than 0.990, the amorphous volume fractions (AVFs) (corresponding to glassy phase) of slags were approximately similar, despite of the cooling ways. At <0.674 basicity, 80–90% AVFs were observed for water-quenching slags that could encapsulate heavy metals in silicates net structures to inhibit metal leaching in TCLP tests. The <0.511 basicity is required to form glassy slags if using air cooling. In general, the slag’s acid-corrosion resistance is better for glassy structures than for crystalline phases according to SEM, XRD, and TCLP examinations.
Keywords: Melting, Fly ash, Metal, Basicity, Amorphous

並列關鍵字

Melting ； Fly ash ； Metal ； Basicity ； Amorphous

參考文獻

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