The loss of heat dissipation on the surface of the furnace body and the failure of heat storage in the masonry in industrial furnaces is generally about 24~45% of the fuel consumption. When the structural material of the furnace body is made of lightweight bricks with low thermal fusion and small thermal conductivity, fuel consumption can be significantly reduced; at the same time, as the furnace can be rapidly heated up and cooled down, it can improve the production efficiency of the equipment; it can also reduce the weight of the furnace body, simplify the structure of the furnace body, improve the quality of the product, reduce the ambient temperature and improve the labor conditions.
Lightweight refractories have a loose structure and a large porosity within the material, which has the disadvantage of poor slag resistance. Slag can quickly invade the brick’s porosity and break it, so it cannot be used in direct contact with liquid metal and slag; at the same time, due to its poor wear resistance, low mechanical strength, and poor thermal stability, it cannot be used as a load-bearing structure. It should not be used in contact with the furnace charge, which is easy to wear.
Due to the above disadvantages, light refractories are not used in industrial furnaces where they are in contact with the charge, in the hearth, in the slag, and hot air streams with high velocities and mechanical vibrations. Light refractories are mainly used as insulation or thermal insulation for furnaces. The main lightweight refractory products currently in use are zirconia hollow balls, alumina hollow balls, lightweight mullite bricks, lightweight, high alumina bricks, lightweight clay bricks, and refractory fibers are currently in everyday use as the current lightweight insulation