Hearth is holding molten iron and slag, and coke combustion produces a large number of gas, make the initial conditions for blast furnace reduction. Hearth area especially in tuyere zone is in the highest temperature area of the blast furnace, the temperature at 1700 ~ 2000 ℃, the bottom of the furnace temperature is in commonly 1450 ~ 1500 ℃. Hearth lining besides subjected to high temperature, also the main chemical erosion and erosion by the iron slag, furnace bottom are mainly composed of molten iron into erosion. At the same time of molten iron into, alkali and zinc also invaded. Molten iron breach can cause surface of refractory brick, the expansion of the chemical erosion can cause embrittlement refractory brick layer, thus result in serious damage of the bottom of the blast furnace refractory material. These parts require a refractory erosion resistance, permeability resistance to molten iron, the thermal conductivity of the alkali resistance and volume stability and appropriate.
Is one of the important parts of blast furnace hearth. This part is the main reason of the lining damage: the erosion of slag and molten iron. Alkali erosion; High temperature gas flow erosion; The destruction of the thermal stress; The oxidation of CO2, O2 and H2O, erosion, etc.
The parts of the lining damage is the result of comprehensive shaping of many factors, both chemical, thermal, also have the effect of the machinery. So, hearth with refractory performance shall meet the following requirements:
Around 1500 ℃ high temperature resistance, hot metal temperature, slag temperature higher;
Erosion resistance, such as high temperature furnace slag erosion, especially when alkali metal and oxide in the slag erosion sex is stronger, the second is the erosion of molten iron, and the erosion of CO, CO2, H2O; Resistance to erosion and abrasion resistance; The permeability resistance;
High thermal conductivity.
Hearth tuyere zone can adopt corundum - mullite brick or corundum brick, sillimanite brick; Can be used in the hot surface of the molten slag contact general ceramic refractory corundum - mullite bricks or brown corundum brick, choose in grim dense carbon bricks or graphitization, semi graphitized carbon brick, also can choose a small piece of microporous carbon brick, moulded carbon brick; Furnace bottom to choose half graphite carbon brick, microporous carbon bricks, furnace bottom leveling layer with a layer of graphitized carbon brick.
