Last issue we introduced thermal insulating refractory material used at blast furnace tap hole. This issue we will introduce thermal insulating refractory material used at blast furnace hearth and furnace bottom.  

     Thermal insulating refractory material used at blast furnace hearth and furnace bottom. The temperature at top of furnace hearth is very high. The temperature near the tuyere is above 1700~2000 C. The temperature at furnace bottom is 1450?1500°C. The lining of furnace hearth has to endure erosion and scouring of slag and molten iron. The bottom of furnace is mainly damaged by infiltration of molten iron. While the molten iron infiltrates, alkali and zinc also infiltrate..

     The infiltration of molten iron can cause the refractory brick to float, and the chemical erosion can cause the expansion of the embrittlement layer of the refractory brick, thereby causing serious damage to the thermal insulating refractory material of the blast furnace bottom. If the refractory bricks in these parts are damaged, to repair the refractory bricks in these parts are not easy. And the damage of these parts determines the service life of the blast furnace.

     The thermal insulating refractory material used at this part should be resistant to erosion of melted iron, resistant to soaking of melted iron, resistant to alkali, stable in dimension and should have suitable heat conduction. At present, the refractory materials used at the bottom of the blast furnace (from the upper part of the bottom of the furnace) are mainly clay bricks, high alumina bricks and carbon blocks. Large and medium-sized blast furnaces now use graphite carbon bricks and microporous carbon bricks with high density, high thermal conductivity and high corrosion resistance.