Fireclay Refractory brick for blast furnace is used in the part of throat, stack, hearth, bottom for a small blast furnace and the stack for a big blast furnace. NRCL manufactuer a compelete ranges fireclay bricks for blast furnaces.
Firebricks are composed from a blend of usually two or more clays. The use of flint and kaolin clays imparts refractoriness, calcined clays (chamottes) control the drying and firing shrinkages and plastic clays facilitate forming and bonding strength. Fireclay bricks are usually grouped into the following categories.
Super-duty bricks (PCE > 33) have a typical alumina content of 40 to 45%; they have a good refractoriness, resistance to thermal shock and volume stability at higher temperatures.
High-duty firebricks (PCE 31 ½ to 33) are similar to super duty equivalents but will be typically manufactured from lower quality flint clays/chamottes and plastic clays (typical Al2O3 40 to 45%). High-duty firebricks are commonly used as a replacement for medium duty firebricks where thermal cycling is a potential problem.
Medium-duty firebricks (PCE 29 to 31) (typical Al2O3 38 to 42%) are used in less severe applications. Thermal shock resistance in these products is lower than on super & high duty firebricks.
Low-duty firebricks (PCE 15 to 29) (typical Al2O3 35 to 38%) are used as backing linings and other applications where moderate temperatures are prevalent.
Semi Silica firebricks have typical alumina contents of 18 to 25% with silica values ranging 72 to 80%. They have excellent load bearing strength and volume stability at relatively higher temperatures