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Purging plug with slits is widely used in the secondary refining process, and its service life determines the downtime and production efficiency. To achieve a good performance in service life, optimizing the geometric structure of the slit, which can alleviate the stress concentration around the slit, was employed using the finite plate model. Furthermore, the performance of the purging plugs with different shapes of slits in the refining effect was investigated by conducting the water model experiments. The numerical simulation results showed that the appropriate shapes of slits could alleviate the stress concentration phenomena. In the water model experiment, the mixing time of the purging plug with circular slits is lesser than that of the purging plug with rectangular slits when the gas flow is less than 6.02 L/min. Compared with the rectangular slits, the circular slits are detrimental to smaller and well-distributed bubbles. Thus, the inclusion removal rate of the purging plug with circular slits is approximately 10% larger than that of the purging plug with the rectangular slits.

Purging plugs employed in ladles in the steel industry undergo severe thermomechanical loads owing to the cyclic operations, including preheating, transporting, stirring, and holding stages. For the smooth running of the process with less downtime, the lifespan of the purging plug needs to be aligned with the overhaul interval without failure. In the present study, to identify the thermomechanical failure mechanisms of corundum castable purging plugs with different slit structures via a quantitative evaluation method, the Drucker–Prager material constitutive model was applied to account for the irreversible behavior. The results indicate that both shear and tensile failure occur in the purging plug with rectangular slits, where the shear failure dominates in the middle of the holding stage and tensile failure appears during the stirring stage. Moreover, the premature shear failure occurs in the upper section near the working face for both types of purging plugs. The application of circular slits diminishes the stress concentration in the purging plug and changes the fracture mechanisms, extent, and occurrence time, which experience mere shear failure in the early stage of transportation.

The new route for recycling fly ash was proposed to prepare SiC reticulated porous ceramics (SRPCs) with high strength and increased efficient filtration for molten metal filtration. The effects of fly ash on the rheological characteristics, microstructure evaluation and wetting behavior between SRPCs and molten metal were investigated. It was found that the fly ash was beneficial to thixotropic property of SiC slurry when its content was less than 30 wt%. Furthermore, fly ash in SRPCs was completely transformed into mullite with needle-shape at 1300 °C, forming a porous structure containing micro pores and windows. SRPCs containing 20 wt% fly ash exhibited a higher strength because of the improved rheological properties of SiC slurry and the optimized microstructure in skeleton. In addition, the added fly ash in SRPCs could increase the contact angle between skeleton substrate and molten metal via microporosization of skeleton, thus exhibiting the potential ability to improve the filtration efficiency.