Reactivity of Coke Ash on Alumina-Carbon Blast Furnace Hearth Refractories

摘要

Understanding the degradation of blast furnace hearth refractories by coke ash products is a crucial component in achieving long furnace life. This study has been conducted to determine the reactivity of calcium aluminates (CaO·Al_(2)O_(3), CaO·2Al_(2)O_(3) and CaO·6Al_(2)O_(3)) in contact with an alumina-carbon refractory at representative hearth temperatures of 1450° to 1550°C.The rate of reaction between the alumina-carbon refractory and calcium aluminates was observed to increase with CaO content. The largest reaction layer was observed in CaO·Al_(2)O_(3) followed by CaO·2Al_(2)O_(3) and CaO·6Al_(2)O_(3). The calcium aluminate (CaO·Al_(2)O_(3), CaO·2Al_(2)O_(3)) and alumina-carbon reactions observed in this study were found to be consistent with the logarithmic rate law, with the exception of CaO·6Al_(2)O_(3) where no reaction was observed.Energy dispersive spectroscopy analysis indicated the formation of CaO·2Al_(2)O_(3), CaO·6Al_(2)O_(3), corundum (Al_(2)O_(3)), plagioclase (CaO·Al_(2)O_(3)·2SiO_(2)) and melilite (2CaO·Al_(2)O_(3)·SiO_(2)) at the reaction interface of the reaction couples. The large volume changes due to the formation of these phases may result in spalling at the hot face of the hearth refractory.