Refractories For Furnace Hearth And Furnace Bottom

The hearth is the place where molten iron and slag are contained, and coke is burned to produce a large amount of gas, which creates initial conditions for the reduction of the blast furnace. The hearth, especially the tuyere area is the highest temperature area in the blast furnace, with a temperature of 1700-2000°C and a furnace bottom temperature of 1450-1500°C. In addition to being affected by high temperatures, the hearth lining is mainly subjected to chemical erosion and erosion of slag and iron, and the bottom of the furnace is mainly eroded by the infiltration of molten iron. At the same time as the molten iron invades, alkali and zinc also invade. The intrusion of molten iron can cause refractory bricks to float up, and chemical erosion can cause the expansion of the embrittlement layer of refractory bricks, thereby causing serious damage to the refractory materials at the bottom of the blast furnace. These parts require refractory materials to have the corrosion resistance of molten iron, resistance to penetration of molten iron, alkali resistance, volume stability, and suitable thermal conductivity.

The hearth is an important part of the blast furnace. The main causes of lining damage in this part are erosion of slag and molten iron; erosion of alkali metal; erosion of high-temperature gas flow; destruction of thermal stress; oxidation and erosion of CO2, O2, H2O, etc.

The damage to the lining in this part is the result of the comprehensive action of many factors, including chemical, thermal, and mechanical. Therefore, the performance of refractory materials for hearth should meet the following requirements: high-temperature resistance, the temperature of molten iron is about 1500 ℃, and the temperature of slag is higher; corrosion resistance, such as the erosion of high-temperature slag, especially the erosion of alkali metals and oxides in slag Stronger, followed by the erosion of molten iron, as well as the erosion of CO, CO2, H2O; erosion resistance, wear resistance; permeability resistance; high thermal conductivity.

Hearth tuyeres can be made of corundum mullite bricks or brown corundum bricks, sillimanite bricks; ceramic refractory materials such as corundum mullite bricks or brown corundum bricks can generally be used on the hot surface in contact with molten iron and slag, and dense Carbon bricks or graphitized, semi-graphitized carbon bricks, small pieces of microporous carbon bricks, molded carbon bricks can also be used; semi-graphite carbon bricks, microporous carbon bricks are used for the bottom of the furnace, and a layer of graphitized carbon is used on the leveling layer of the furnace bottom brick.