Thermophysical Properties of Modified Ti-bearing Blast Furnace Slags

摘要

Our study investigated the influence of P_2O_5 and B_2O_3 on the viscosity and crystallization behavior of Ti-bearing blast furnace (Ti-BF) slags for the purpose of Ti extraction. The investigation of the crystallization behaviors were carried out using a single hot thermocouple technique (SHTT) and the viscosity was obtained by rotating cylinder method. For the viscosity, the results showed that P_2O_5 substantially increased the slag viscosity. P_2O_5 is a network-forming oxide, which increased the degree of polymerization of slags and accordingly increased the slag viscosity. However, both of slag viscosity and apparent activation energy for viscous flow remarkably decreased with B_2O_3 addition. As a typical network forming oxide, B_2O_3 was introduced into the network and existed dominantly as 2-D structure, BO_3 triangular, which caused a simpler structure and a decreasing slag viscosity. As for the crystallization behaviors of Ti-BF slags, both P_2O_5 and B_2O_3 enhanced the crystallization trend of rod-shape rutile and suppressed the crystallization trend of dendrite CaTiO_3. Therefore the added P_2O_5 and B_2O_3 caused the primary phase change from CaTiO_3 to rutile. Additionally, it was found that the rod-shape rutile showed a 1-D growth, whereas the dendrite CaTiO_3 showed a 3-D growth style.