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研究生： 蘇同新
Su, Tung-Hsin
論文名稱： 煉鋼燒結與轉爐石淋溶過程中磷賦存狀態之探討
Phosphorus redistribution during iron ore sintering and BOF slags leaching
指導教授： 楊懷仁
Yang, Huai-Jen
學位類別： 碩士
Master
系所名稱： 理學院 - 地球科學系
Department of Earth Sciences
論文出版年： 2008
畢業學年度： 96
語文別： 中文
論文頁數： 186
中文關鍵詞： 矽酸二鈣 、轉爐石 、淋溶 、脫磷 、燒結
外文關鍵詞： BOF-slag, dephosphorization, sintering, leach, dicalcium silicate
相關次數： 點閱：100  下載：2 
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    • 轉爐煉鋼製程，透過移除硫、矽、磷與碳雜質之程序，將轉爐中的鋼冶煉成磷與硫含量均低於0.010％純淨鋼。純化過程伴隨產生的渣即為轉爐石，約佔煉鋼總重量10％，其資源化是鋼廠運作重要環節。一般粗粒轉爐石安定化處理後可用於道路鋪面或水泥原料，細粒轉爐石目前尚無法有效回收。轉爐石成分主要為40~50％ CaO、15％ Fe2O3、10％ SiO2與6~7％ MgO，且含少量硫及約1％磷。高鈣與高鎂特性，可取代 如大理石、蛇紋石與白雲石等助熔劑回收於燒結製程。但轉爐石含約1％磷，會導致燒結礦磷含量過高。因磷會降低鋼鐵材料之延展性與抗腐蝕性，若欲將轉爐石回收於燒結製程必須將磷移除。本研究詳細探討煉鋼燒結與轉爐石淋溶過程中，磷在各礦物相之賦存狀態，作為設計將轉爐石回收於燒結製程之依據。

    燒結反應嘗試以雙氧水與尿素改變燒結氣氛，或以焦炭將磷還原並藉由氣體或粉塵形式脫除。結果顯示燒結過程磷富集於玻璃中（P2O5 0.2~2％；多數＞ 1％），而燒結礦中結晶礦物相多數不含磷，僅少數樹枝狀結晶物質與鐵酸鈣中含磷（P2O5 < 1％）。主要元素分析顯示燒結前後磷總量無明顯變化（燒結前約0.08％；燒結後約0.1％），推論是雙氧水與尿素比例不正確或強度不足，或在發揮作用前隨即分解。焦碳與轉爐石加熱後磷含量並未減少，推論為溫度太低所致（實驗1350 ℃，文獻1600 ℃）。水與稀鹽酸淋溶結果轉爐石中矽酸二鈣確實會分解且部分鈣溶於水中，但溶解比例偏低（鈣最多僅0.1克），多數矽酸二鈣與水反應產生不含磷之氫氧鈣石。EDS分析轉爐石中磷主要富集於矽酸二鈣，ICP-OES與ICP-MS分析淋溶殘留固體磷含量並未降低，為淋溶過程殘留之矽酸二鈣會更加富集磷所致。因此淋溶脫磷可考慮使用大量或流動性質的液體，確保淋溶後轉爐石沒有矽酸二鈣殘留。整體而言，燒結反應中熔融物質與結晶相之間經降溫而趨於平衡作用下，磷偏好進入熔融物質，並淬冷封存於玻璃中。而淋溶作用下磷偏好賦存於轉爐石內殘留之矽酸二鈣，造成淋溶後之殘留轉爐石磷含量並未減低。

    The basic oxygen steel-making process removes sulfur, phosphorous, carbon, and silicon impurities from molten iron into “slag”, which makes up 10% of the total weight during steel-making, and the recycling of the so-called “BOF” slag has been an important issue for the operation of a steel-making plant. The coarse-grained BOF slag can be used as road building materials and raw material for cement. The fine-grained BOF slag, however, has not been efficiently recycled. The BOF slag is composed of 40~50％ CaO, 15％ Fe2O3, 10％ SiO2, 6~7％ MgO, < 1% sulfur, and ~1% phosphorous. The high CaO and MgO contents of the BOF slag make it a possible candidate replacing fluxes, such as marble, serpentine, and dolomite, in iron-ore sintering. However, phosphorous has to be removed prior recycling to the sintering process as it reduces the ductility and corrosiveness-resistance of steel. In order to found a basis for recycling BOF slag to iron-ore sintering, this research investigates the distribution of phosphorous during iron-ore sintering and leaching of BOF slag.
    In an attempt to remove phosphorous, hydrogen peroxide, carbamide, and coke were added into the raw materials for sintering. The results show that glass derived from partial melting of sintered materials is the major host of phosphorous. Calcium ferrite and some crystals of a dendritic phase might contain less than 0.4% of phosphorous. There is no significant variation in phosphorous concentration prior and post the sintering process, implying that insufficient hydrogen peroxide and carbamide was added or that this approach is not appropriate. Interaction between BOF slag and coke at 1350 ℃ did not resulted in phosphorous removal, either, possibly because the temperature did not reach that for thermal equilibration between these two phases. Leaching BOF slag with water and HCl did dissolve small amounts of dicalcium silicate with the formation of Ca(OH)2. Phosphorous is concentrated in dicalcium silicate. However, the phosphorous content of the residues after acid and water leaching increases because of decreasing the weight of the residues. It is inferred that leaching the BOF slag with large amount of running water could completely dissolve the dicalcium silicate in BOF-slag. Dephosphorization can therefore be achieved. It is concluded that phosphorous is an incompatible element during iron-ore sintering and prefers to enter melts, which form glass after quenching. Dicalcium silicate is the dominant phosphorous-hosting phase in the water and acid-leached residues. Phosphorous concentration will not decrease until completely dissolution of dicalcium silicate from leaching residues.

    摘要...................................................................Ⅰ Abstract...............................................................Ⅱ 致謝...................................................................Ⅲ 章節目錄..............................................................Ⅳ表目錄.................................................................Ⅶ圖目錄.................................................................Ⅷ 第一章 序論............................................................1 1.1 前言............................................................1 1.2 研究目的........................................................3 1.3 文獻分析........................................................4 1.3.1 磷對鋼的影響..............................................4 1.3.2 高爐與轉爐脫磷............................................4 1.3.3 高爐製程前脫磷............................................5 1.3.4 燒結礦淋溶脫磷............................................5 第二章 研究方法與原理..................................................7 2.1 轉爐石回收燒結試驗..............................................8 2.1.1 三公斤燒結鍋燒結實驗......................................8 2.1.2 紅外線快速升溫爐.........................................13 2.2 轉爐石淋溶試驗.................................................15 2.2.1 水洗淋溶.................................................15 2.2.2 酸洗淋溶.................................................17 2.3 分析方法.......................................................18 2.3.1 X光螢光分析.............................................18 2.3.2 燒失量分析...............................................18 2.3.3 X光繞射分析.............................................18 2.3.4 掃描式電子顯微鏡與能量散射光譜儀.........................19 2.3.5 感應耦合電漿質譜儀與感應耦合電漿原子發射光譜儀...........20 2.3.6 標準添加法...............................................22 第三章 實驗結果.......................................................23 3.1 轉爐石回收燒結試驗結果.........................................23 3.1.1 三公斤燒結杯.............................................23 主要元素.................................................23 EDS分析結果.............................................25 電子顯微鏡影像觀察.......................................30 反射式顯微鏡.............................................45 燒失量...................................................48 X光繞射分析.............................................49 3.1.2 紅外線快速升溫爐.........................................53 3.2 轉爐石淋溶試驗結果.............................................54 3.2.1 水洗脫磷.................................................54 3.2.2 酸洗淋溶.................................................57 第四章 討論...........................................................58 4.1 轉爐石燒結試驗與磷賦存狀態之探討...............................58 4.1.1 三公斤燒結杯.............................................58 燒結礦磷含量之變化與富集機制.............................58 礦物相形成機制與主要元素氧化物變化.......................60 轉爐石之組成礦物與形成機制...............................64 燒失量與XRD分析結果.....................................73 轉爐石中礦物相比例.......................................74 4.1.2 紅外線快速升溫爐.........................................76 4.2 轉爐石淋溶試驗與磷賦存狀態之探討...............................79 4.2.1 淋溶試驗中水溶液與殘留固體之元素含量變化.................79 4.2.2 酸洗淋溶殘留固體之磷含量變化.............................81 4.2.3 磷之遷移行為.............................................82 第五章 結論...........................................................85 5.1 燒結脫磷與磷賦存狀態之探討.....................................85 5.2 淋溶脫磷與磷賦存狀態之探討.....................................86 參考資料...............................................................88 附件...................................................................91

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