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系統識別號 U0026-1507202015523000
論文名稱(中文) 以碳熱還原法去除轉爐石中的磷
論文名稱(英文) Removal of phosphorus from steel-making slag by carbothermic reduction
校院名稱 成功大學
系所名稱(中) 環境工程學系
系所名稱(英) Department of Environmental Engineering
學年度 108
學期 2
出版年 109
研究生(中文) 林鈺婷
研究生(英文) Yu-Ting Lin
學號 P56074068
學位類別 碩士
語文別 英文
論文頁數 106頁
口試委員 指導教授-劉守恒
口試委員-朱信
口試委員-魏玉麟
口試委員-黃武章
中文關鍵字 鹼性氧氣爐渣(轉爐石)  脫磷  鹽基度 
英文關鍵字 basic oxygen furnace slag  dephosphorization  basicity 
學科別分類
中文摘要 鹼性氧氣爐(BOF)爐渣是煉鋼的主要副產品之一,隨著鋼產量的增加,爐渣產生的增長率也在增加。由於轉爐爐渣中的大多數元素都是有益成分,因此可以在煉鋼過程中作為原料再利用。但是,鹼性氧氣爐渣中的高磷含量限制了其在煉鋼過程中的循環利用。轉爐爐中大部分的磷會與矽酸二鈣(Ca2SiO4, C2S)結合形成Ca2SiO4˖Ca3(PO4)2固溶體。因此,在不引起其他有害影響的情況下除去爐渣中磷的方法來提高轉爐石的循環利用是迫切急需的。本實驗研究了從轉爐爐渣中還原P2O5的方法。在不同溫度(1500℃和1600℃)的條件下,將石墨、二氧化矽、氯化鈣和氯化鈣作為脫磷劑,並以XRF分析爐渣的化學成分、XRD鑑定結晶相、ICP-OES測水中磷與鐵中磷含量以及EMPA與WDS進行爐渣相的成份定性及定量分析。實驗結果顯示,SiO2有利於爐渣中磷的還原,但是過多的SiO2可能引起再磷化現象。Al2O3有利於鐵的還原,但會形成Ca2Al2O7的相,不利於磷的還原。CaCl2在800-900℃下會分解成CaO而提高鹼度,因此顯著降低了磷的還原。而在還原溫度為1500℃下,石墨比例為7wt. %、二氧化矽比例為5wt. %時有最佳的磷蒸發速率。此外,在1600℃時,石墨比例為7 wt. %、二氧化矽比例為10 wt. %的條件下有最佳脫磷率。實驗後的EPMA觀察到大部分磷集中在金屬相中且磷會隨著石墨添加量增加而提升。
英文摘要 Basic oxygen furnace (BOF) slag is a main byproduct in steelmaking and the growth rate of slag generation is increasing as steel production increases. Due to most of the elements in the converter slag are beneficial components, it can be reused as a raw material in the steelmaking process. However, the high phosphorus content in the basic oxygen furnace slag limits its recycling in the steel-making process. Most of phosphorus in BOF slag is incorporated with Ca2SiO4 to form a Ca2SiO4˖Ca3(PO4)2 solid solution. Therefore, it is necessary to find a method to remove phosphorus in slag without causing other harmful effects, in order to activate BOF slag recycling. In this work, the reduction of P2O5 from the BOF slag was investigated. Graphite, SiO2, CaCl2 and Al2O3 were used as dephosphorization agents under conditions of different temperatures (1500°C and 1600°C). The chemical compositions of the slag are analyzed with XRF. The crystalline phases of the slag are obtained by XRD. The phosphorus contents in the iron particles and solution are analyzed by ICP-OES. Elemental mapping and compositional analysis of P-phase of the slags are quantitatively characterized using EMPA and WDS analysis. The experimental results show that SiO2 favors reduction of phosphorus in the slag, but excess SiO2 may cause re-dephosphorization. The Al2O3 is good for reduction of iron, but it decreases the reduction of phosphorus due to the formation of Ca2Al2O7. Due to the dissociation of CaCl2 into CaO at 800-900°C, the increased basicity inhibits the dephosphorization. The best phosphorus vaporization rate is carried out at1500°C, with the graphite and SiO2 mixing ratio of 7 wt.% and 5 wt.%, respectively. Moreover, the best dephosphorization rate under conditions of 7 wt.% C and 10 wt.% SiO2 at 1600°C. EPMA observation of the slag after the experiment showed that most of phosphorus concentrated in the metal phase and the content of phosphorus in the metal phase increase with the increasing of graphite content.
論文目次 CONTENTS
摘要 I
ABSTRACT III
LIST OF TABLES VII
LIST OF FIGURES X
CHAPTER 1 INTRODUCTION 1
1.1 Background 1
1.2 Objectives 2
CHAPTER 2 LITERATURE REVIEW 3
2.1. Basic Oxygen Furnace (BOF) slag 3
2.2. Phosphorus reduction 5
2.2.1 Carbo-thermic reduction method 6
2.2.2 Magnetic separation method 8
2.2.3 Leaching method 10
2.2.4 Capillary action method 13
2.3. Basicity 21
2.4. Temperature 26
2.5. Al2O3 modifications 28
2.6. CaCl2 modifications 32
CHAPTER 3 METHODOLOGY 42
3.1 Experimental Procedure 42
3.1.1 Chemical 42
3.2 Experimental Flowchart 43
3.2.1 Research Equipment 44
3.2 Materials 45
3.2.1 Industrial BOF slag preparation 45
3.2.2 Preparation of dephosphorization agent 45
3.3 Characterization and Analysis 46
3.4.1 X-ray Flouresence (XRF) 46
3.4.2 X-ray Diffractometer (XRD) 47
3.4.3 Inductively coupled plasma optical emission spectrometry (ICP-OES) 47
3.4.4 Field emission electron probe micro-analyzer (EPMA) 48
CHAPTER 4 RESULTS AND DISCUSSION 49
4.1. Effect of temperature on dephosphorization 49
4.2. Effect of SiO2 on dephosphorization 52
4.2.1 The slag with 7 wt.% C and various amounts of SiO2 at 1500°C 52
4.2.2 The slag with 7 wt. % C and various amounts of SiO2 at 1600°C. 58
4.3. Effect of Al2O3 on dephosphorization 64
4.4. Effect of CaCl2 on dephosphorization 70
4.5. Effect of graphite amounts on dephosphorization 75
4.5.1 Effect of temperature on dephosphorization 76
4.5.2 Effect of SiO2 on dephosphorization 84
4.6. Mass balance 97
4.7. Mechanism of dephosphorization during carbothermic reduction 100
CHAPTER 5 CONCLUSION 102
REFERENCES 103
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