Insulating refractory

The refractory mix for forming high strength, low thermal conductivity brick consisting, for each 100% by weight thereof, of 45 to 75% by weight of a dense refractory aggregate which is a calcined clay, calcined bauxite, calcined bauxitic kaolin, kyanite or mixture thereof, 10 to 30% by weight of a bonding agent which is a ball clay, bentonite, or mixture thereof, 5 to 25% by weight of a lightweight aggregate consisting of hollow silica-alumina microspheres having a diameter of about 30 microns.

The refractory mix for forming high strength, low thermal conductivity brick consisting of, for each 100% by weight thereof, 45 to 75% by weight of a dense refractory aggregate which is a calcined clay, calcined bauxite, calcined bauxitic kaolin, kyanite or mixture thereof, 10 to 30% by weight of a bonding agent which is a ball clay, bentonite, or mixture thereof, 5 to 25% by weight of hollow ceramic microspheres consisting of hollow silica-alumina microspheres having a diameter of about 30 microns, and a pressing aid for assisting in forming the brick during pressing.

The refractory mix for forming high strength, low thermal conductivity brick consisting, for each 100% by weight thereof, of 45 to 75% by weight of a dense refractory aggregate which is a calcined clay, calcined bauxite, calcined bauxitic kaolin, kyanite or mixture thereof, 10 to 30% by weight of a bonding agent which is a ball clay, bentonite, or mixture thereof, 5 to 25% by weight of hollow ceramic microspheres consisting of hollow silica-alumina microspheres having a diameter of 30 to 300 microns, 5 to 15% by weight of a lightweight aggregate which is a bubble alumina, perlite, vermiculite, diatomite, expanded shale, clay, or mixture thereof, and a pressing aid for assisting in forming the brick during pressing.