Heavy refractory bricks are refractory materials which have better tolerance to high temperature and abrasion, so they are mostly used as working layer or permanent layer materials for industrial kilns to prevent high temperature solutions from causing damage to the kiln body and to protect the thermal-protective layer. Lightweight refractory bricks are heat-insulation bricks suitable for low temperature environment, and are mostly used for insulating layer of the kiln or thermal equipment to reduce heat loss and save energy.
(1) Different production process. Heavy high alumina brick is made of bauxite chamotte as the main raw material, and soft clay and spent pulping liquor as the binding agent after high pressure forming, drying and high temperature firing. Lightweight high alumina bricks are made of bauxite chamotte mixed with clay binding agent and foaming agent after being cast moulded and fired at high temperature. They are both sintered refractory bricks, one is formed under high pressure, and the other under cast moulding.
(2) Different bulk density. The heavy high alumina bricks have compact bulk density of 2.3-2.65 g/cm3 with a low porosity less than 23%, while lightweight high alumina bricks have low density of 0.6-1.5 g/cm3 with a high porosity more than 45%.
(3) Different refractory temperature. The refractory temperature of heavy high alumina bricks is around 1580-1790 degrees, which means they have good high temperature resistance. Lightweight high alumina bricks are used at about 1350-1500 degrees.
(4) Using in different parts. Higher refractory temperature of heavy high alumina bricks decides they can be used in the parts which contact with slag or solution, have low porosity, and strong resistance to penetration. Lightweight high alumina brick having low using temperature, high porosity, and cannot be in contact with the flame or slag which is easy to damage the bricks by permeating into them, so they are mostly used for thermal insulating layer material.