Effect of Al2O3 mass fraction on viscosity behavior of CaO-SiO2-MgO-Al2O3-B2O3 slag system under different conditions
LIANG Ziming1,2,3, CHU Mansheng1,2,3, LIU Zhenggen1,2,3, LI Shubao4
1. School of Metallurgy, Northeastern University, Shenyang 110819, Liaoning, China; 2. Liaoning Low-carbon Steelmaking Technology Engineering Research Center, Northeastern University, Shenyang 110819, Liaoning, China; 3. Engineering Research Center of Frontier Technologies for Low-carbon Steelmaking(Ministry of Education), Shenyang 110819, Liaoning, China; 4. Technology Quality Department, Nanjing Steel, Nanjing 210035, Jiangsu, China
Abstract：Utilization of cheap ludwigite and high alumina ore in blast furnace smelting is one of the important measures to reduce cost and increase efficiency for iron and steel enterprises. However, it is easy to change the mass fraction of Al2O3 and B2O3 in blast furnace slag, which has an important effect on the operation of blast furnace. Therefore, the systematic study for influence of Al2O3 mass fraction on the high alumina slag containing boron under different conditions is of great significance for the optimization and controlling of blast furnace slag. The influence of Al2O3 mass fraction on the viscosity behavior of CaO-SiO2-MgO-Al2O3-B2O3 slag system under different conditions was studied by rotating cylinder method. The results show that, when w(MgO)/w(Al2O3) changes, mass fraction of Al2O3 increases from 12.28% to 19.95%, the viscosity η1 500 ℃ of slag increases from 0.236 Pa·s to 0.272 Pa·s, melting temperature TBr increases from 1 258 ℃ to 1 310 ℃, and the silical-aluminate network structure in slag is gradually gathered and the degree of polymerization increases, which leads to the fluidity of slag become worse. With the increasing of Al2O3 mass fraction from 12.28% to 14.51%, viscous activation energy Eη changes slowly from 144.92 kJ/mol to 152.68 kJ/mol, and when the mass fraction of Al2O3 increases from 14.51% to 19.95%, Eη increases significantly from 152.68 kJ/mol to 176.70 kJ/mol, then the thermal stability of slag is decreased sharply. When w(MgO)/w(Al2O3) is constant at 0.47, with the increasing of Al2O3 mass fraction from 11.00% to 13.00%, η1 500 ℃ of slag decreases slowly from 0.243 Pa·s to 0.242 Pa·s and TBr increases slowly from 1 243 ℃ to 1 251 ℃. When the mass fraction of Al2O3 increases from 13.00% to 19.00%, η1 500 ℃ of slag increases significantly from 0.242 Pa·s to 0.264 Pa·s, TBr increases significantly from 1 251 ℃ to 1 313 ℃, then the silical-aluminate network structure in slag gathers, and the fluidity of slag is deteriorated. Eη shows an overall increasing trend in the range of 156.76-174.46 kJ/mol, and the thermal stability of slag becomes worse. In conclusion, when w(MgO)/w(Al2O3) changes, slag with Al2O3 mass fraction of 14.51% has better viscosity behavior. When w(MgO)/w(Al2O3) is constant at 0.47, the slag with mass fraction of Al2O3 less than 13.00% has better viscosity behavior. This study can provide theoretical guidance for the use of ludwigite in blast furnace smelting.
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2023, Vol. 33 
