Plugging pressure of blast furnace tap hole mix depends on its deformation behavior, which is generally evaluated with an extruding load in Marshal test at 50 to 80℃. However, this evaluation occasionally does not conform to the expected plugging pressure at blast furnace. Based on a hypothesis that the evaluation of tap hole mix deformation at elevated temperature, where liquid tar added to tap hole mix exhibits the lowest viscosity, would give better predictability, the shear test which enables to evaluate deformation at high temperatures was developed. Comparing the shear test results at 70℃ and 300℃ with plugging pressure, it is concluded that the evaluation at 300℃ correlates with plugging pressure better than the evaluation at 70℃. Furthermore, contributions of raw material’s characteristics and temperature on the shear test results were analyzed quantitatively.

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The present study demonstrates that the sine rule is useful for examining the interfacial free energies at solid－liquid-gas interface, when the dissolution reaction from solid ceramic to molten metal has occur and reached equilibrium. The mean value of the interfacial free energy between carbon saturated molten nickel and graphite obtained is 1.89±0.05J･m－2, and one of the surface free energy of graphite is 0.75±0.10J･m－2.

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