Blast furnace taphole is a channel to lead out high-temperature molten iron or slag. In the production process, it is subject to the destructive effects of several factors as follows:
(1) Violent scouring and erosion of flowing high-temperature molten iron and slag.
(2) Chemical erosion of blast furnace slag.
(3) Violent thermal shock damage of intermittent tapping.
Therefore, the cast iron ditch lining is required to have the following characteristics:
(1) The refractory lining of iron tapping ditch has strong resistance to erosion and scouring of high-temperature molten iron and slag.
(2) It has excellent high temperature resistance and wear resistance.
(3) The chemical corrosion resistance of high temperature slag is strong.
(4) The thermal shock resistance is good, and the re burning change is small.
(5) Strong resistance to all kinds of oxidation.
(6) It is easy to construct, dismantle and repair, does not produce harmful gas, and is conducive to environmental protection.
The materials used in the taphole of foreign large blast furnaces can be divided according to different parts by referring to the refractory materials used in Blast Furnaces:
(1) Corundum silicon carbide carbon refractory bricks are used for the main ditch.
(2) The hot metal branch ditch uses high alumina clinker silicon carbide carbon series refractory bricks.
(3) Clay clinker (or bauxite clinker) "silicon carbide" carbon series refractory bricks are used for slag branch ditches.
There are iron leakage port and iron breaking port at the iron tapping port. The iron leakage port is opened to a certain extent, and there is iron seepage, but the iron port is not fully opened, and the iron tapping time is long. The iron port is opened to a certain extent and cannot be drilled. Usually, the iron port can be opened by burning, but sometimes it needs to be stuffy.
From top to bottom, the blast furnace body is divided into five parts: furnace throat, furnace body, furnace waist, bosh and hearth. Due to the advantages of good technical and economic indicators, simple process, large production capacity, high labor production efficiency and low energy consumption, the iron produced by this method accounts for the vast majority of the total iron output in the world. During blast furnace production, iron ore, coke and slag forming flux (limestone) are loaded from the top of the furnace, and preheated air is blown from the tuyere located at the lower part of the furnace along the periphery of the furnace. Under high temperature, the carbon in coke (some blast furnaces also inject pulverized coal, heavy oil, natural gas and other auxiliary fuels) and the carbon monoxide and hydrogen generated by the combustion of oxygen blown into the air will remove the oxygen in iron ore during the rising process in the furnace, so as to obtain iron. The molten iron is discharged from the iron mouth. Unreduced impurities in iron ore combine with fluxes such as limestone to form slag, which is discharged from the slag mouth. The produced gas is discharged from the top of the furnace and used as fuel for hot blast stove, heating furnace, coke oven, boiler, etc. after dust removal. The main products of blast furnace smelting are pig iron, as well as blast furnace slag and blast furnace gas.