The iron content of iron ore is called grade. Before smelting, it must be carefully selected to remove other impurities and improve the grade of iron ore. And then sent to a blast furnace for smelting after crushing, grinding and sintering.
Coke provides heat and produces reducing agent carbon monoxide. Limestone is used for slagging and gangue removal, so that iron produced by smelting can be separated from impurities. The main equipment for ironmaking is blast furnace. Iron ore, coke and limestone are added from top to bottom during smelting, and hot air is blown into the furnace from bottom to top. At high temperature, the reactants fully contact and react to obtain iron.
Blast furnace ironmaking is to put iron ore, coke, carbon monoxide, hydrogen and other fuels and fluxes (in theory, iron can also be mixed with ores with stronger metal activity and smelted at high temperature) into the blast furnace for smelting, and remove impurities to obtain metallic iron (pig iron).
Extended data
At high temperature, the carbon in coke and injection and carbon monoxide produced by carbon combustion take away the oxygen in iron ore and get iron. This process is called reduction. Iron ore is refined into pig iron through reduction reaction, and molten iron is discharged from the taphole. Gangue in iron ore, ash in coke and injection are combined with flux such as limestone added into the furnace to generate slag, which is discharged from the taphole and slag outlet respectively.
The gas is led out from the top of the furnace and used as industrial gas after dust removal. Modern blast furnaces can also use the high pressure at the top of the furnace and some derived gases to generate electricity.
During gas operation, gas operators should wear portable gas alarm and be supervised by special personnel.
It is also prone to burns in front of the furnace. The main preventive measures are to improve the equipment level, and the operators should wear protective clothing. Raw material yards and furnaces are also prone to vehicle injuries and machine injuries.
In the bituminous coal pulverizing and injection system, when the volatile matter of bituminous coal exceeds 10%, a dust explosion accident may occur. In order to prevent dust explosion, measures such as controlling the temperature of coal mill and controlling the oxygen content in the air in coal mill and dust collector are mainly taken. In China, the method of injecting blended coal is often used to reduce the volatile content.
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