臺灣博碩士論文加值系統

煉鋼爐渣是煉鋼行業的主要副產品之一，隨著鋼鐵產量的增加，爐渣的增長速度也在增加。雖然煉鋼過程中的爐渣可以回收利用，但由於磷的高濃度，其回收率受到限制。如果可以减少爐渣中的磷，則可以在煉鋼過程中回收爐渣，最终我們可以减少CaCO3的消耗，CaCO3是二氧化碳排放的主要來源之一。本研究的目的是以最環保的方式减少BOF爐渣中的磷（P），並以矽鐵（FeSi）為還原劑，加入SiO2以降低各種爐渣的鹼度，確定還原後磷的分布。XRF結果顯示，在反應溫度1500℃，含有3%（重量）FeSi和10%（重量）SiO2的情况下，爐渣中磷的還原效果最好。ICP-MS數據顯示，在1500℃的温度下，具有3wt%的FeSi和5wt%及10wt%的SiO2有磷氣化的較佳结果。根據ICP-MS數據的質量平衡計算結果，樣品中超過50%的P可能被氣化。

Steelmaking slag is one of the major byproducts from the steelmaking industry, and the growth rate of slag generation is increasing as steel production increases. Although the slag of steelmaking process can be recyclable, it is limited in its recovery due to the high concentration of phosphorus. If phosphorus in the slag could be reduced, the slag could be recycled in the steelmaking process, and eventually we could decrease the consumption of CaCO3 which is one of the major sources of CO2 emissions. The aim of this thesis was to reduce the phosphorus (P) from BOF slag with the most environmental friendly way and determine the distribution of phosphorus after reduction by using ferrosilicon (FeSi) as reductant and addition of SiO2 to lower the basicity of slag at various temperature (1300, 1400, and 1500 oC). The main results of this research are that FeSi proven to be able to reduce phosphorus from BOF slag. XRF data showed 2 best results of phosphorus reduction from slag with condition 1500oC with 3 wt% FeSi and 10 wt% SiO2. ICP-MS data showed 2 best results of phosphorus vaporization with condition both samples are at temperature of 1500oC, with 3 wt% FeSi and 5wt% + 10 wt% SiO2. Based on the mass balance calculation by ICP-MS data, more than 50% of P from the samples might be vaporized. Overall, temperature of 1500oC is preferable to have higher reduction percentages of phosphorus from solid phase and vaporization.

CONTENTS
摘要 i
ABSTRACT ii
LIST OF TABLES v
LIST OF FIGURES vi
CHAPTER 1 INTRODUCTION 1
1.1 Background 1
1.2 Objectives 3
CHAPTER 2 LITERATURE REVIEW 4
2.1 Basic Oxygen Furnace (BOF) Slag 4
2.2 Phosphorus reduction 5
2.2.1 Magnetic Separation method 6
2.2.2 Leaching method 12
2.2.3 Capillary Action method 15
2.2.4 Carbothermic Reduction method 25
2.3 Slag Basicity 26
2.4 Temperature 28
2.5 Slag Modifications 28
2.6 Ferrosilicon 29
2.7 P in Fe-Si 30
2.8 Thermodynamics of P in molten FeSi 33
2.9 P in Slag 36
2.10 Kinetics of phosphorus removal 37
2.11 Conditions for Phosphorus Evaporation 38
2.12 Distribution of P between slag and Si 39
CHAPTER 3 METHODOLOGY 40
3.1 Research Equipments 40
3.2 Experimental Flowchart 40
3.3 Preparation of Slag Sample 45
3.4 Preparation of Reductant 45
3.5 FactSage Process 45
3.6 Characterization and Analysis 46
3.6.1 X-ray Flouresence (XRF) 47
3.6.2 X-ray Diffraction (XRD) 47
3.6.3 Scanning Electron Miscroscopy (SEM) + Energy Disperse Optical Spectrum (EDS) 48
3.6.4 Inductively coupled plasma mass spectrometry (ICP-MS) 48
CHAPTER 4 RESULTS AND DISCUSSION 49
4.1 Thermodynamic Modeling by FactSage Software 49
4.1.1 Sample at 1300oC 50
4.1.2 Sample at 1400oC 52
4.1.3 Sample at 1500oC 54
4.2 Slag Characterization 55
4.2.1 Physical characterization 55
4.2.2 XRF Analysis 60
4.2.3 XRD Analysis 62
4.2.4 SEM Analysis 65
4.2.5 ICP-MS Analysis 76
4.3 Phosphorus distribution between FeSi + Slag with XRF analysis and FeSi + SiO2 + Slag with ICP-MS analysis. 77
4.3.1 FeSi with Slag 77
4.3.2 FeSi + SiO2 + Slag at 1500oC (slag part only) 82
4.3.3 FeSi + SiO2 + Slag at 1500oC (metal part only) 83
4.3.4 Condition for Phosphorus Vaporization 85
4.4 Influence of SiO2 Addition as Basicity and Temperature 86
CHAPTER 5 CONCLUSION 89
REFERENCES 90

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