低碳鋼爐渣脫硫能力之熱力學計算研究

Thermodynamic Calculations of Desulfurization in Low Carbon Steel-Slag Systems

屈耿立(Keng-Li Chu)

指導教授 ： 陳貞光

國立臺北科技大學/工程學院/材料及資源工程系研究所/碩士(2014年)

https://doi.org/10.6841/NTUT.2014.00473

摘要

隨著目前科技進步對於鋼鐵材料的品質也越來越嚴格，為了降低鋼中雜質，本研究設計一系列CaO-Al2O3-SiO2為基礎的三元系統脫硫渣，結合MnO、MgO、CaF2、TiO2、Na2O與B2O3等成分進行研究，利用熱力學軟體Thermo-Calc及SLAG數據庫進行鋼鐵冶煉之模擬研究，了解爐渣成分對於脫硫效果的影響。本研究固定原始鋼液中硫含量為500 ppm，保持熔煉溫度並針對爐渣量以及爐渣成分進行變化，計算鋼液和爐渣在熱力學反應平衡後之硫含量，藉以觀察爐渣對鋼液之脫硫能力。計算結果顯示在1600°C、3 wt.%的爐渣量添加時，隨著CaO比例超過50 wt.%後，硫分配比的上升趨勢非常顯著，其脫硫率達64.71%、硫分配比(Ls)達62.02具最佳脫硫效果，而進行二次精煉後更可將脫硫率提升到75.69 %、Ls 108.28。除了基本的三元爐渣外，MnO在SiO2超過25%且其含量高於CaO時，對於爐渣的脫硫效果是有幫助的；在爐渣添加CaF2，對於爐渣的脫硫效果不佳，但可以降低爐渣熔點、提高流動性，因此提高脫硫反應動力學之成效；而Na2O與B2O3也都有降低爐渣熔點之效果。本研究顯示，含有較高CaO成分的爐渣脫硫能力明顯較佳，而低鹽基度的爐渣中MnO的脫硫效果較CaO為佳，而Na2O、B2O3、CaF2等熔劑對脫硫的熱力學反應上幫助有限，但因其降低爐渣熔點、提高爐渣與鋼液之反應，有助於達成熱力學平衡。

關鍵字

熱力學 ； 爐渣 ； 脫硫 ； 鹽基度 ； 硫分配比

並列摘要

To reduce impurities in the steel melts, the current study designs a series of CaO-Al2O3-SiO2 ternary systems of desulfurization slags, combining MnO, MgO, CaF2, TiO2 , Na2O, and B2O3 to evaluate their desulfurization capability using a thermodynamic calculation software, Thermo-Calc. A low carbon steel melt with sulfur content of 500 ppm is considered. The study varied melting temperature, amount of slag, and slag composition to evaluate their sulfur partition ratio. The results demonstrate that, at 1600 °C and the amount of slag kept at 3 wt.%, sulfur partition ratio significantly increases with CaO. The desulfurization rate was 64.71% and sulfur partition ratio of 62.02 was achieved. After secondary refining, the desulfurization rate was further raised to 75.69% and sulfur partition ratio increased to 108.28. When SiO2 exceeds 25 wt.%, MnO outperforms CaO in desulfurization. The addition of CaF2 decreases the sulfur partition ratio, while CaF2 also decreases melting point of the slags, improving mobility and thus benefits the kinetics of desulfurization reactions. Both Na2O and B2O3 also have the similar effects of reducing the melting points of the slags. In conclusion, the desulfurization capacity increases mainly with amount of CaO in the slags. MnO could aid to desulfurize in slags of lower basicity. CaF2, Na2O, and B2O3 all demonstrate only limited capacity for desulfurization, however they can lower the melting temperatures of slags and aids to the desulfurization reactions.

並列關鍵字

Thermodynamics ； slag ； desulfurization ； basicity ； sulfur partition ratio

參考文獻

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