台灣地區的都市垃圾處理已經趨向於利用焚化處理方式,其焚化過程後所產生的灰渣開始走向零廢棄及再利用之目標。但由於焚化飛灰為重金屬含量較高之物質,常因重金屬的高溶出而被判定為有害廢棄物,對環境潛在的危險性也較大,因而使飛灰的再利用遭受限制。 在多個研究中發現,利用垃圾焚化底渣燒結成再生性常重骨材的可行性極高,研究結果顯示可作為再生之結構性骨材使用,大幅提高再生骨材使用範圍與其經濟價值。此外,水庫淤泥在適當燒結條件之下,也有出現輕質化之現象,因此將以焚化底渣及飛灰作為研究主要材料添加水庫淤泥,藉由廢棄性材料進行調質,來探討受熱膨脹與燒製成輕質骨材的成效。 細粒徑底渣和飛灰在經過前處理步驟後,確實可降低灰渣內的水溶性氯鹽含量,提高材料再利用的價值,利用水庫淤泥進行調質燒製輕質骨材,控制燒結條件下,預熱5分鐘,預熱溫度為500℃,燒成時間為5~10分鐘,燒成溫度為1,170℃。混合灰添加水庫淤泥的調配條件大致可以確定為水庫淤泥需大於70%。 混合灰燒製的輕質骨材在TCLP測定中展現其相當安定的特性,皆為法規標準五分之一。工程性質試驗上,密度可低於1 g/cm3,膨脹效果相當明顯,骨材表面緻密,吸水率因而不高,對於未來輕質混凝土試驗中的泵送性和灌鑄性有相當大之助益,在健度方面可通過CNS規範,如此可表示燒製出的粒料品質是相當穩定及耐用。
The municipal solid waste incinerator (MSWI) fly ash is regarded as hazardous waste in many countries because the analysis of toxicity characteristics leaching procedure (TCLP) test could not compliance with the current EPA regulation usually. At present, the fly ash treatment processes are solidification and then landfill in Taiwan, which faced the risk of long term leaching of heavy metals. This study discussed the feasibility about the municipal solid waste incinerator (MSWI) ash sintering as lightweight aggregate. Water-extraction was applied in the beginning; in order to remove the harmful soluble salts during the regeneration process; proper addition the reservoir sediments to enhance the operation and property during the sintering process. The MSWI ash samples were composed of the fly ash and fine grain of bottom ash (particle size smaller than 74.5μm). Under the condition of 5-10 minutes of sintering time in 1,170oC, addition of 50-100 % of the reservoir sediment, lightweight aggregate product with the properties of the density lower than 1.0 g/cm3 and the compression strength up to 15kgf/cm2 could be generated. Which could be satisfied the common criteria of the construction materials, and the heavy metals leaching potential are far below the TCLP regulation.