A study on dephosphorization during steel-making by using an recycled slag

• Main Authors: Jhih-Hong Chen, 陳志宏
• Other Authors: 吳威德
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/87567428916545612855

碩士 === 國立中興大學 === 材料科學與工程學系所 === 101 === A new dephosphorization agent was developed by mixing different amount of recycled ladle furnace slag and lime. Different agents were experimented on 50Kg molten iron in an induction furnace, and each agents and slag were examined using X-ray fluorescence analyzer (XRF), chemical titration analysis, X-ray diffraction (XRD), differential thermal analysis (DTA), a spark discharge component analysis spectrometer (Spark) and scanning electron microscopy (SEM). Effect of different recycled slag and lime ratio on dephosphorization during steelmaking was examined, and the feasibility using recycled slag in steelmaking was discussed. Experimental results show that dephosphorization increase as lime content increases in the agent. The agent with 100 wt% recycled ladle furnace slag has only 13% dephosphorization ratio. As the amount of lime increases to 25 wt%, the agent shows more than 60% dephosphorization ratio. Discussions reveal that the amount of F-CaO affects the dephosphorization behavior. The higher F-CaO content in dephosphorization agent, the better dephosphorization results, and the relation between dephosphorization ratio and F-CaO is: Dephosphorization ratio(%) =-67.1926e ([F.CaO% ]⁄12.35942 ) +74.54785 It was also discovered that more Al2O3 was drawn into molten steel with increasing lime content in dephosphorization agent. It will lead to rephosphorization phenomenon during steel making. Blending recycled slag and lime properly can promote liquefaction of dephosphorization agent, improve dephosphorization ability, lower the probability of rephosphorization and reduce damage to the environment.