Reaction Between K2O and Al2O3-SiO2 Refractories as Related to Blast-Furnace Linings |
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Authors: | S E McCUNE T P GREANEY W C ALLEN R B SNOW |
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Affiliation: | Research Center, United States Steel Corporation, Monroeville, Pennsylvania |
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Abstract: | An examination was conducted to determine the mechanism of peeling of fire-clay brick in the low-temperature region of a blast furnace where 3 to 10% K2O is the principal contaminant. In laboratory tests, as-received high-duty and superduty fire-clay brick and 70% alumina brick treated with KCl-K2CO3 mixtures showed no peeling at a temperature of 1600°F. Cracks were found in high-duty brick that were treated with KCN at 1500°F. under partially reducing conditions. X-ray diffraction studies of mixtures of crushed brick and K2CO3 indicated the formation of leucite (K2O.Al2O3.4SiO2) and kaliophilite (K2O.-Al2O3.2SiO2) at temperatures below 1700°F. These latter data, confirmed by specimens from used blast-furnace linings, showed that silica is the first constituent attacked by alkali. Since the formation of leucite and kaliophilite in fire-clay brick is the probable cause of peeling, the increased reaction of silica, in a dense Al2O3.SiO2 refractory of higher silica content than fire-clay brick, should confine the alkali attack to the surface of the brick in low-temperature applications. |
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