Effects of Deadman State on the Safety of Locally Eroded Blast Furnace Hearth: A Multiphysics Coupling Modeling Study

The service state of the blast furnace (BF) hearth directly determines the furnace's lifespan, and its failure carries significant economic and safety risks. The safe service state of the BF hearth depends on three key parameters: the chemical dissolution rate of the carbonaceous lining, the growth thickness of the solidified iron protective layer (SIPL), and the stress state of the lining material under thermal-mechanical loads. Based on the actual hearth operating conditions, this study established a three-dimensional thermal-fluid-concentration-structure coupling simulation model for the locally eroded hearth. This model considers conjugate heat transfer, carbonaceous concentration transport, molten iron solidification, and thermal stress in refractory materials. It systematically analyzes the influence of the deadman state parameters (floating height, bottom diameter, angle of repose, and bottom shape) on the safety of the hearth lining. The results show that increasing the deadman floating height and controlling its bottom diameter and angle of repose at a low level can effectively promote the formation of the SIPL, homogenize thermal stress, and inhibit carbon dissolution, thereby significantly delaying the lining erosion process. Compared with the flat-bottom deadman, the spherical-bottom deadman offers advantages in thickening the SIPL, reducing thermal stress, and lowering carbon dissolution loss, thereby effectively extending the hearth lifespan. The research findings provide important theoretical basis and operational guidance for the long-life operation of BF hearths.