In the process of blast furnace production, iron ore, coke and slag-making flux (limestone) are loaded from the top of the furnace, and preheated air is blown in along the furnace circumference from the tuyere located at the lower part of the furnace. Carbon in coke at high temperature (some blast furnaces also inject auxiliary fuels such as pulverized coal, heavy oil and natural gas). ) burns with oxygen blown into the air to generate carbon monoxide and hydrogen, and the oxygen in the iron ore is removed in the process of rising in the furnace, thus reducing to obtain iron. The molten iron is discharged from the taphole. Unreduced impurities in iron ore combine with fluxes such as limestone to form slag, which is discharged from the slag outlet. The generated gas is discharged from the top of the furnace and used as fuel for hot blast stoves, heating furnaces, coke ovens and boilers after dust removal. The main products of blast furnace smelting are pig iron, as well as by-products blast furnace slag and blast furnace gas. Blast furnace smelting is a continuous production process of reducing iron ore into pig iron. Iron ore, coke, flux and other solid raw materials are fed into the blast furnace in batches from the top charging device according to the specified batching ratio, and the throat material level is kept at a certain height. Coke and ore form an alternating layered structure in the furnace. Mineral materials are gradually reduced and melted into iron and slag in the descending process, which are gathered in the furnace and discharged from the taphole and slag outlet regularly. After the cold air sent by the blower is heated to 800 ~ 1350℃ in the hot blast stove, it continuously and stably enters the furnace through the tuyere, and the hot air burns the coke in front of the tuyere to generate thermal reducing gas above 2000℃. The rising high-temperature airflow heats iron ore and flux to make them become liquid; And make the iron ore complete a series of physical and chemical changes, while the airflow gradually cools down. Strong heat and mass transfer process between downgoing gas column and updraft. The capillary water in the falling material will evaporate when heated to 100 ~ 200℃, while the crystal water in limonite and some gangue will decompose and evaporate at 500 ~ 800℃. The main fluxes limestone and dolomite, as well as other carbonates and sulfates, are also decomposed by heat in the furnace. The decomposition temperatures of CaCO3 in limestone and MgCO3 in dolomite are 900 ~1000℃ and 740 ~ 900℃ respectively. Iron ore is reduced in a blast furnace at 400℃ or slightly lower. Part of the iron oxide is melted in the slag at a lower high temperature, and then the iron is reduced from the slag. Electric furnaces are generally smelted with scrap steel. Converter generally uses molten steel from blast furnace for smelting.