Classification of lightweight refractory bricks

September 12, 2018

Classification of lightweight refractory bricks

Lightweight refractory brick is a kind of insulating refractory products,  refers to refractory brick with high porosity, low bulk density and low thermal conductivity. Lightweight refractory bricks are characterized by porous structure (porosity generally 40% to 85%) and high heat insulation.

There are several classification methods for lightweight refractory bricks:

(1) Volume density. Lightweight refractory bricks having a bulk density of 0.4 to 1.3 g/cm3; and ultra-light refractory bricks of less than 0.4 g/cm3.

(2) Usage temperature. The use temperature is 600 ~ 900 ° C for low temperature insulation materials; 900 ~ 1200 ° C for medium temperature insulation materials; over 1200 ° C for high temperature insulation materials.

(3) Product shape. One is a shaped lightweight refractory brick, including insulated refractory fire clay bricks, high alumina refractory bricks, silicon refractory bricks and some pure oxide lightweight refractory bricks; the other is amorphous lightweight refractory bricks. Such as lightweight refractory concrete.

The heat loss of industrial kiln masonry and on the surface of the industrial furnace generally account for 24% to 45% of fuel consumption. The use of lightweight refractory bricks with low thermal conductivity and low heat capacity as the structural material of the furnace can save fuel consumption. At the same time, because the furnace can be heated and cooled rapidly, the production efficiency of the equipment can be improved; the weight of the furnace can be reduced, and the kiln structure can be simplified. Therefore it can improve the quality of refractory bricks, reduce the ambient temperature and improve working conditions.

The disadvantages of lightweight refractory bricks are large porosity, loose structure and poor slag resistance. The slag quickly invades into the pores of the refractory brick body, causing it to be broken, and cannot be used for direct contact with molten slag and liquid metal parts. Low mechanical strength, poor wear resistance and poor thermal stability, can not be used for load-bearing structures, and should not be used in areas that are in contact with the charge and are heavily worn.

Because of the above disadvantages, lightweight refractory bricks in industrial furnaces are generally not used in furnace parts where slag is in contact with the charge, slag and hot gas flow at high flow rates, and where mechanical vibration is large. Lightweight refractory bricks are often used as lagging, lining or insulation for kiln.