Research on characteristics and modelling estimation of molten BF slag viscosity in the process of slag waste heat recovery

Abstract

The object of this study was to explore the effects of basicity (CaO/SiO 2 ratio), MgO and Al 2 O 3 on viscosity and melting temperature of molten slag in the process of coal gasification with blast furnace (BF) slag as heat carrier to recover the waste heat. The results showed that the viscosity and melting temperature of BF slag decreased first and then increased with CaO/SiO 2 ratio increasing, and the suitable CaO/SiO 2 ratio was 1.10-1.20. Both viscosity and melting temperature increased with the increasing of MgO and Al 2 O 3 in the slag, which should be lower than 8.22 and 11.00%, respectively. What is more, the viscosity estimation model for molten BF slag was established according to the Urbain model and experimental data of slag viscosity. In the model, the activation energy was calculated using slag compositions based on the redefine of material types in the slag, and the temperature was described by the Weymann-Frenkel equation. The viscosity of BF slag system estimated by proposed viscosity estimation model (modified Urbain model) fitted well with the experimental data and the mean deviation was about 17.98%.

Review of pellets and blast furnace slag research progress: the effects of MgO on metallurgical properties

“…The influence of basicity (CaO/SiO 2 ) on slag properties is self-evident [93][94][95], and the optimum basicity of blast furnace slag is between 1.0 and 1.2. MgO has numerous advantages in the blast furnace slag, but it should be added in moderation [96]. The content of MgO in the slag system is not unlimited, especially when there is a large amount of Al 2 O 3 in the slag system, and MgO/Al 2 O 3 ratio is an important indicator [97,98].…”