廢耐火材料轉製水淬高爐石資源應用及實場試驗之研究

中鋼受限於分類設備與堆存空間，廢耐火材料尚未完全有效資源化再利用。其中，以含MgO之廢耐火材料因會水化膨脹，處理難度最高，難以資源化再利用。若委外掩埋處理，則會衍生高額處理費用。針此，中鋼乃將廠內廢耐火材料依氧化鎂（MgO）含量分為4大類：高鎂（MgO ＞ 40%）、中鎂（20% ＜ MgO ≦ 40%）、低鎂（5% ＜MgO ≦ 20%）、微鎂（MgO ≦ 5%）。當中，高鎂、中鎂與微鎂廢耐火材料三者已達產銷平衡，唯低鎂廢耐火材料以負效益方式去化，無法有價再利用。基於循環經濟理念，本研究開發一種將低鎂廢耐火材料轉換為有價水淬高爐石的技術。先將低鎂廢耐火材料研磨至≤ 10 mm，於高爐出鐵過程中投入，利用鐵水高溫將其與高爐石熔融在一起，並經水淬製程轉換為非晶型態的水淬高爐石作為水泥原料。首先，將研磨後之低鎂廢耐火材料以1～3 wt%不同比例添加入水淬高爐石中，分析對水淬高爐石的熔融溫度及對流道耐材抗侵蝕性之影響。實驗結果顯示水淬高爐石之熔融溫度隨低鎂廢耐火材料添加量上升而微幅升高，對流道耐火材之抗蝕性則無明顯影響。基於爐渣熔點影響考量，選定1%作為添加量至高爐主流道實測，結果顯示水淬高爐石仍可維持非晶相、膨脹率0.023%（規範≤ 0.08%）、MgO含量6.52 wt%（規範≤ 10 wt%）、FeO含量0.35 wt%（規範≤ 3 wt%）、S含量0.61wt%（規範≤ 2 wt%），性質皆符合水泥廠允收規範。本技術可將現況以負效益去化的廢耐火材轉製為有價水淬高爐石外售，增加中鋼集團收益，提供另一資源化途徑。

關鍵字

廢耐火材料；氧化鎂；水淬高爐石；非晶相

並列摘要

China Steel Corporation (CSC) is limited by sorting equipment and storage space, resulting in waste refractories had not been effectively recycled. Waste refractories containing MgO are difficult to be recycled due to its hydration and expansion. If outsourcing landfill disposal will incur high disposal costs. If outsourcing landfill, it will incur high disposal costs. Therefore, China Steel divides waste refractories into 4 categories based on MgO content: High-type (MgO＞40%), medium-type (20%＜MgO ≦ 40%), low-type (5%＜MgO ≦ 20%) and extra low-type (MgO ≦ 5%). The waste refractories with high, medium and extra low magnesium oxide have reached a recycled balance, but only low-type is reused in a negative benefit. Based on the circular economy, this study develops a technology to convert low-type waste refractories into valuable quenched blast furnace slag. First of all, the low-type waste refractories are ground to ≤ 10mm ant put into the main trough of blast furnace. The waste refractories and the slag are melted together via the high temperature of the molten iron, and the converted into amorphous quenched blast furnace slag through the water quenching process. The quenched blast furnace slag will be used in cement application and have better strength than traditional Portland cement. In laboratory test, low-type waste refractories were added to blast furnace slag at a rate of 1~3 wt% to analyze the effects on the melting temperature of slag and the erosion resistance of the main trough refractories. The results reveal that the melting temperature of slag tiny increases with the addition of low-type waste refractories but no significant effect on the corrosion resistance of the runner refractories. Based on the consideration of slag melting temperature, 1 wt% addition of low-type waste refractories is selected to the CSC on-site test. The analysis results show that the quenched blast furnace slag is still remain amorphous phase, the expansion rate and chemical contents are all in specifications for cement application. This technology can convert the waste refractories into valuable quenched blast furnace slag to increase CSC revenue and provide innovative recycled way.