| 摘要: | 摘 要 Thermite 反應為還原態金屬與氧化態金屬或非金屬之間的高放熱氧化 還原反應並為自行傳播反應，一經點燃，反應傳播延續至終止且產生高純 度之產物，此特性具有低成本、省能、高品質之熔融技術開發價值。 廢棄物資材中工業下腳料鋁渣含有還原態金屬鋁、鋼鐵業副產物轉爐 礦泥、熱軋礦泥以及紡織廠廢水污泥含有氧化鐵、電弧爐集塵灰含有氧化 鋅與氧化鐵、印刷電路版蝕刻污泥含有氧化銅與氧化鐵。於本研究中根據 Thermite 反應原理將此六種廢棄物資材配製成五種具有行Thermite反應潛 力之熔融劑並稱之為廢棄物衍生Thermite熔融劑（Waste Derived Thermite, WDT ）並依序為WDT1~WDT5五種熔融劑且進行評估研究。配方評估試 驗以最高反應溫度決定五種WDT最佳配比，結果WDT1為鋁渣：轉爐礦泥 =28%：72%；WDT2為鋁渣：蝕刻污泥=18%：82%；WDT3為鋁渣：熱軋 礦泥=25%：75%；WDT4為鋁渣：電弧爐集塵灰=33%：67%；WDT5為鋁 渣：紡織廠廢水污泥=28%：72%。五種最佳配方WDT處理焚化飛灰試驗， 以WDT1處理0~21.5wt.%飛灰，反應溫度可達1329℃~ 894℃ 之間，減少 熱損失之高溫熔融處理試驗則熔融溫度為2047℃~ 1236℃ 之間；以WDT2 處理0~29.1wt.%飛灰，反應溫度可達1577℃~923℃之間，高溫熔融處理則 為2286℃~1168℃之間；以WDT3處理0~16.3wt.%飛灰，反應溫度可達 1246℃~882℃ ， 高溫熔融處理則為1766℃~1198℃ ； 以WDT4 處理 0~21.2wt.%飛灰，反應溫度可達1117℃~ 982℃ 之間；以WDT5處理 0~28.2wt.%飛灰，反應溫度可達1126℃~789℃之間。反應後熔渣主要晶相 物種在 WDT1、WDT3、WDT4、WDT5組之共同成分為Al2O3、Fe、CaAl4O7 及SiO2；WDT 4可分析出ZnO2及FeO； WDT5可分析出FeO。WDT2主要物 種僅Al2O3、Cu及SiO2。高溫熔融產物熔渣與金屬錠之分離效果良好， WDT1、WDT2及WDT3產物之金屬錠所佔百分比由15~5％（含鐵量92~94 ％，WDT2含銅量91％~74％），高溫處理後產物之金屬錠上升至33~18％。 熔渣呈現黑色堅硬玻璃質狀， TCLP溶出符合環保署法規限值，顯示熔渣 安定性及可再利用價值。綜合反應溫度、單位放熱值、產物特性、點燃反 應難易度、反應自傳播特性等指標評估五種WDT，結果以WDT1及WDT2為 最佳、WDT3次之、WDT 4與WDT5較不適。 Abstract The thermite reaction is defined as the oxidation-reduction reactions between a metal and other metallic/ non- metallic oxides which are characterized by large exothermic heat and the self-sustaining of the process. The large exothermic energy can be used as an extremely efficient energy for purifying ores for some metals, or for the detoxifying of the MSWI fly ash. Typical thermite reaction (a type of aluminothermic reaction) is one in which aluminum metal is oxidized by an oxide of another metal, most commonly iron oxide. These thermite reactants can be provided with by industrial waste streams containing aluminum and related oxides, thus giving an excellent opportunity to develop effective thermite from wastes for energy. Accordingly, this study tried to develop thermites from wastes (referred to as wastes-derived-thermite, WDTs) , and further to evaluate the feasibility of treating the MSWI fly ash by use of the WDTs. In this study, except for aluminum scrap, five types of candidate dust and sludge were primarily screened based on the analysis of the waste compositions and possible thermite reactions estimated, these candidate wastes including aluminum scrap/dross, converter sludge from steel making plants (Convert-sludge), printed circuit board sludge (PCB-sludge), hot rolling wet dust (HR-dust) and electric arc furnace dust (EAF dust) from steel making plants, and sludge from cotton mill industry wastewater treatment plants (referred to as fabric dyeing sludge, FD-sludge). The proper formula for the WDTs were to be generated on the evaluation of the performance criteria such as the effective energy generated by the unit WDT, the sustainability of the reaction, and the mobility of heavy metals during the reaction. Laboratory testing results showed that proper formula (i.e., iron oxide containing waste : aluminum scrap, wt%) generated for the five tested wastes, in the increasing order of the dust/sludge percentage were EAF dust (67wt.%), converter sludge (72wt.%), FD-sludge (72wt.%), HR-sludge (75wt.%), and PCB-sludge (82wt%), indicating the reactive oxides decreased in as the weight percentage for dust/sludge increased. WDT from PCB-sludge outperformed the other WDTs in melting 0-29.1wt% MSWI fly ash (reaching a melting temperature ranging from 2286 to 1168℃). The larger treating capacity for MSWI fly ash showed that high thermite energy released by the copper oxide in the plating sludge contributed to the melting process. WDT from converter sludge also showed a 0-21.5 wt% treating capacity for MSWI fly ash (reaching a melting temperature ranging from 2047 to 1263℃). The hot-rolling sludge showed less treating capacity for MSWI fly ash (0-16.3wt%, with temperature reaching 1766 to 1198℃). The results of the TCLP test for all the recovered slags generated form the melting process of WDTs and fly ash showed that the leaching concentrations of target metals were all in compliance with the USEPA's regulatory threshoulds, ensuring the safety of the slag. The common components identified by the XRD techniques included Al2O3, Fe, CaAl4O7, and SiO2 for all tested WDTs except for WDT from PCB-sludge in which Cu was identified. This results reported here suggest that it is feasible to generate aluminothermic thermite from aluminum scrap/dross and wastes containing iron oxide, copper oxide, and/or other related oxides. These WDTs can not only recover slag and alloy by thermite reactions, but also be used as fuel in detoxifying MSWI fly ash by melting process, showing a promising energy efficient, recycling-beneficial alternative. |
