Abstract:Study and Optimization of viscosity on Ansteel BF slag is done in a laboratory with actual ironmaking BF slag as specimen. The content of CaO、SiO2、Al2O3、MgO and dualistic basicity are the variables. By changing one variable and keeping the rest constant, slag of different content of MgO and Al2O3, as well as different basicity are produced, their viscosity and melting temperature are mensurated respectively. The results showed that the best BF slag basicity should be between 1.05 and 1.10, with MgO content of between 8 to 10% and Al2O3 less than 14%.