| In recent years,the development of larger and longer-lasting blast furnaces has resulted in intensified smelting strength,posing a significant challenge to the refractory materials used in blast furnaces.The iron trough of blast furnace,which serves as a vital channel for the transportation of molten iron,is particularly vulnerable due to its exposure to harsh conditions such as high temperature,hot metal erosion,severe temperature fluctuations,and slag erosion.As a consequence,the iron trough requires frequent refractory replacement,making the quality of refractory materials a critical factor for ensuring the continuous operation of the blast furnace.Currently,the iron trough of the blast furnace is plagued by problems such as invisible operation processes and poor anti-scour and anti-thermal shock performance of castables,leading to unclear damage mechanisms,frequent large-area repairs,and other issues that adversely affect the normal operation of blast furnaces.This study employs numerical simulation using ANSYS to investigate the operational process of the blast furnace’s main iron trough and to explore the relationship between damage and the working conditions of the furnace and refractory materials.To enhance the thermal conductivity,physical properties,and thermal shock resistance of Si C whiskers,Fe-Si3N4 is introduced to generate Si C whiskers in situ.Furthermore,in light of the development trend of the enclosed iron trough,this study examines the influence of oxygen partial pressure on the castables properties of the iron trough,and calculates the phase composition using Fact Sage thermodynamic software.Based on the aforementioned experiments and analyses,the following conclusions can be drawn:（1）The numerical simulation study presented in this paper reveals several critical issues in the operational process of the blast furnace’s iron trough.Firstly,the shear force of molten iron on the wall of the iron trough is greater in the contact area between molten iron and air,resulting in more severe scouring of the upper part of the side wall.The shear force increases with the flow velocity of molten iron.Moreover,excessive flow velocity can reduce the separation efficiency of slag and iron,leading to an excessive amount of slag entering the iron trough.Secondly,during the operation of the iron trough,there is a significant temperature difference between the inside and outside,and the temperature field is closely related to the thermal conductivity of the material.When the thermal conductivity increases,the temperature at the bottom of the iron trough rises,while the temperature on both sides of the wall decreases.Finally,the effect of the trapezoidal structure on the stress in the iron trough is studied.After structural optimization,the average thermal stress inside the iron trough decreases,and the distribution becomes more uniform.Simultaneously,the increase in thermal conductivity of the material reduces the thermal stress experienced by the iron trough.（2）In order to enhance the performance of the casting material used in the iron trough,Fe-Si3N4 is introduced in this study to facilitate sintering through the utilization of elemental Fe and its related oxides.At elevated temperatures,Si3N4 reacts homogeneously within the castables to generate Si C whiskers,which increases the binding strength between the matrix and the aggregates,thereby improving the thermal conductivity and thermal shock resistance of the castables.Additionally,Fact Sage thermodynamic software is employed to calculate the phase composition and content of the reaction at the interface between blast furnace slag and the castables of iron trough.The results demonstrate that the introduction of Fe-Si3N4 can produce beneficial phases such as Si C and Al N,which enhance the castables’resistance to slag erosion,while also reducing the dissolution rate of Al2O3.These findings highlight the significant role of Fe-Si3N4 in improving the performance of the castables used in the iron trough.（3）The influence of oxygen partial pressure on the performance of the castables used in the iron trough was investigated.The findings reveal that the variation of oxygen partial pressure has a significant effect on the melilite and Si C phases in the castables.Specifically,under high oxygen partial pressure conditions,the in-situ generation of more melilite phase with Al2O3 occurs due to the oxidation of Si3N4 to Si O2.In contrast,under low oxygen partial pressure conditions,more Si C whiskers fill the pores in the castables,while the expansion effect of the in-situ generated melilite compensates for the shrinkage caused by sintering.These results demonstrate the crucial role of oxygen partial pressure in determining the phase composition and performance of the castables used in the iron trough.Overall,this study provides novel insights into the optimization of castables performance and is expected to contribute to the development of more efficient and durable blast furnace iron trough. |
