Blast furnace, heating furnace and air heating furnace pipes are most important devices in iron-making processes. The use factor of blast furnace is directly relative to the warm air temperature. At present, the warm air temperature of domestic air heating furnace reaches over 1100—1500℃. Therefore, the heat preservation result and useful life of the air heating furnace and warm air duct are very important. If microporous thermal insulation materials are adopted for air heating furnace and warm air duct, the evident following effects can be obtained:

(1) Reduce heat loss, raise the temperature of warm air, save energy and reduce consumption；

(2) Increase the useful life of air heating furnace and warm air duct;

(3) Make shell temp. fall down, reduce the torsion of shell, avoid the air leakage of shell;

(4) Help to improve the use factor of the furnace and reduce the coke ratio.