廢棄物鋁熱反應熔融處理焚化飛灰-熔渣基本特性研究

Melting of the MSWI Fly Ash Using Waste-Derived Thermite --Characteristic Study on the Vitrified Slag

鍾宇翔(YU-HSIANG CHUNG)

指導教授 ： 王鯤生

國立中央大學/工學院/環境工程研究所/碩士(2006年)

摘要

近年來電弧爐集塵灰以及都市垃圾焚化飛灰為有害事業廢棄物之大宗，因此本研究根據鋁熱反應之原理利用電弧爐集塵灰中含大量氧化物(Fe2O3、ZnO)，添加鋁渣配置成廢棄物衍生熔融劑(Waste Derived Thermite WDT )作為熔融時之熱源，以改善傳統熔融耗時且耗能之缺點。並建立此廢棄物衍生熔融劑(WDT)熔融飛灰後之熔渣基本物化性質，以提供熔渣未來資源化可能方向。
研究結果顯示，電弧爐集塵灰：鋁渣＝60：27.91為本廢棄物衍生熔融劑最佳配比，利用此配比之廢棄物衍生熔融劑熔融處理飛灰，約可處理飛灰40%，而飛灰添加率由0%～40%時，反應溫度變化範圍在2067℃～1670℃，飛灰添加率每增加10%，反應溫度約下降97.5℃。
熔融後熔渣之成份以O、Al、Fe為主，其中O約為44.77～46.11%；Al約為23.43～32.04%；Fe約為6.27～11.39%。由熔渣組成成份可知熔渣並非以Ca、Si為主之熔渣，因此其玻璃化之現象並不明顯。熔渣之吸水率均低於10%，符合再生粒料之規範值；而比重範圍在1.65～2.47之間，當比重大於2.2時可當作再生粗粒料及再生細粒料使用，比重在2～2.2之間可當作再生細粒料使用，比重小於2時可考慮作為輕質骨材使用。
熔融後之金屬錠主要成份為鐵，鐵的純度在89.17~98.72%之間，顯示利用本廢棄物衍生熔融劑熔融飛灰可有效於金屬錠相回收鐵，並且可由氣相回收金屬鋅，熔渣為無害化可再利用，由此顯示利用鋁熱法熔融處理具備高度資源化與材料化之發展潛力。

關鍵字

熔渣 ； 廢棄物衍生熔融劑 ； 鋁熱反應 ； 焚化飛灰 ； 電弧爐集塵灰 ； 熔融

並列摘要

Municipal incinerator fly ash (MSW fly ash) and electric arc furnace dust (EAF dust) account for the main stream of the industrial hazadrous wastes in the past decade. Their proper treatment and/or disposal remain a risky, costly, and unsolved issue. This study investigated the feasibility of melting such wastes by using a waste derived thermite (WDT) prepared from the reactive constituents in these wastes. The typical thermite reaction between aluminum dross/scrap and oxides such as Fe2O3 and ZnO in EAF dust can not only contribute to the energy required in melting process but also help activate the melting process from the interior of the ash and dust mixture, thus resulting in a slag of good quality.

The results indicate that a ratio of 2.15 of EAF dust to dross by weight will result in the highest energy generated from unit mixture of the WDT, taking into the consideration of the effects of the inert in the mixture. Furthermore, the WDT thus prepared will allow to treat up to 40% (w/w) of MSW fly ash within a range of melting temperature. The melting temperature deceases from 2067℃～1670℃ with an increase in MSW fly ash from 0~40 %(w/w), dependent on the insulation of the reactor wall and the axillary heating. The main species identified in the retrieved slag include Al2O3, ZnO, Fe, CaAl4O7 and Ca2Al2SiO7. Modification of the mixture with SiO2 results in slag with the formation of SiO2 species, instead of CaAl4O7 and Ca2Al2SiO7. The retrieved alloy contains 89~99%(w/w) of Fe as a major species. From the standard tests conducted on size grading, bulk density, absorption and Mohs'' scale of mineral hardness, it appears that the slag is potentially suitable as recycled aggregates in concrete. Thus as demonstrated in this study from both the material-recycling and energy efficiency points of view, the EAF dust stabilization technology, using waste-derived thermite energy, is both feasible and compelling.

並列關鍵字

Thermite reaction ； MSWI fly ash ； EAF dust ； slag

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