China's Refractories

Abstract: In order to improve the properties of corundum based dispersive purging plugs, dispersive purging plug specimens were prepared using tabular corundum (1-0.15 and ≤0.15 mm) as the aggregates, tabular corundum (≤0.044 mm) andα-Al₂O₃ micropowder (d₅₀=0.6 μm) as the matrix, Secar 71 cement as the binder, introducing different amounts of nano-CaCO₃, casting into shapes, and firing at different temperatures (1 200 or 1 600 °C) for 4 h. The effects of the nano-CaCO₃ extra-addition (0, 0.5%, 1.0%, 1.5% and 2.0%, by mass) on the consistency of the castables as well as the properties and microstructure of the dispersive purging plug specimens were studied. The results show that: (1) with the fixed water addition, the consistency of the corundum castables decreases as the nano-CaCO₃ addition increases; (2) with the increasing nano-CaCO₃ addition, the bulk density of the specimens fired at different temperatures for 4 h decreases, the apparent porosity, the cold strength and the hot modulus of rupture all increase, the gas permeability does not change significantly; (3) the specimens fired at 1 600 °C for 4 h have obviously better cold comprehensive performance than those fired at 1 200 °C for 4 h; (4) when the nano-CaCO₃ addition is 1.5%, the comprehensive performance of the specimen is the optimal.

Key words: dispersive purging plugs, consistency, nano-calcium carbonate