國內廢鋁回收再生工業每年約產生2.1萬公噸之二次鋁渣，而二次鋁渣之組成非常繁雜且不均勻，除鋁元素外尚含氮化物、硫化物、碳化物等，易與水或潮溼空氣反應產生氨氣等惡臭物質。過去鋁渣多以掩埋作為最終處置方法，不但容易造成二度污染，未來也會因掩埋場容量有限而衍生無法去化之窘境。台灣南部地區為廢鋁再生資源化熔煉業者聚集處，長久以來經常發現有鋁渣被任意棄置，或有不肖廢棄物處理業者向不知情之地主承租倉庫違法大量堆置之情形發生。因此，本研究將廢鋁渣與不同濃度氫氧化鈉於凱氏氮蒸餾設備中，進行鋁渣高溫鹼液脫氮反應，期探討最佳操作條件、脫氮效率及反應動力參數。研究結果顯示，於凱氏氮蒸餾設備中使用鹼性試劑氫氧化鈉濃度6N，於反應時間45分鐘、固液比1：25操作條件下，原始鋁渣氮含量由5.57%，降低為0.13%，鋁渣脫氮效率平均可達97.6%，而考量鋁渣於鹼性溶液反應過程之溶解加計重量損失之總脫氮效率可達98.6%，顯示高溫氫氧化鈉溶液對於鋁渣有良好脫氮效果。而套用一階、二階反應動力模式觀察固相氮含量之降低情形可得知0~5分鐘脫氮效率最為迅速，反應速率常數分別可達0.4307 min-1及0.2973 %-1min-1，本研究成果可供鋁渣鹼性高溫條件脫氮工程設計之參考。 The aluminum recycling industry in Taiwan generates twenty-one thousand tons of secondary aluminum dross annually. The composition of this dross is very complex and non-uniform, containing nitrides, sulfides, and carbides, etc., The Aluminum dross easily reacts with water or moisture in the air. It was used to be disposed by landfill with the risks of secondary pollution. Howerer, the space of landfill sites in Taiwan reduces year by year and the cost of landfill increases rapidly. In the southern part of Taiwan, illegal dumping of the waste aluminum dross was offten found.The objective of this study was to examine the effects of different concentrations of sodium hydroxide on removing nitrogen from aluminum dross in the Kjeldahl-nitrogen distillation equipment, and explore the optimal operating conditions. The results showed that (a) the optimal reaction conditions were 6N NaOH with a reaction time of 45 minutes, and a solid-liquid ratio of 1:25, and (b) the nitrogen content of the aluminum dross decreased from 5.57% to 0.13 %, with a nitrogen removal efficiency of 98.6%. Fitting the first, second order reaction kinetic model with the data to evaluate the rate constants. The rate constants were found to be 0.4307 min-1 and 0.2973 %-1 min-1. It could be for the reference in engineering design of alumin dross nitrogen removal in high temperature alkaline solution.
