1. converter steelmaking
The converter is shaped like a pear, with refractory bricks on its inner wall and many small holes (tuyeres) on its side. Compressed air is blown into the converter from these holes, and its main raw materials are pig iron, ore or processed scrap steel. Inject 1300℃ liquid pig iron inward and add a certain amount of quicklime; After oxygen is blown into molten pig iron, the impurities such as carbon, silicon and manganese in it are rapidly oxidized and a large amount of heat is released (containing 1% silicon can raise the temperature of pig iron by 200 degrees Celsius), which can make the furnace reach a sufficiently high temperature. Therefore, converter steelmaking does not need to use additional fuel. Iron, silicon and manganese are oxidized to produce slag, and phosphorus is subsequently oxidized to further produce ferrous phosphate. Ferrous phosphate reacts with quicklime to produce stable calcium phosphate and calcium sulfide, which together become slag. This shows that the steel has been tempered.
2. Open hearth steelmaking
Raw materials: scrap iron, scrap steel, iron ore and limestone. The heat required for the reaction is provided by blast furnace gas or producer gas and heavy oil. At the initial stage of smelting, the fuel meets the introduced hot air and burns on the surface of the fuel, with the temperature as high as 1800 degrees Celsius. Make the burden melt quickly (the melting point of iron is 1535 degrees Celsius, and that of steel is slightly lower). The molten pig iron produces ferrous oxide, and the impurities silicon and manganese in the pig iron are oxidized to produce slag. Limestone and impurities such as phosphorus and sulfur produce calcium phosphate and calcium sulfide as slag. Secondly, carbon will also react to produce carbon monoxide. The smelting process has been completed.
3. Electric furnace steelmaking method
Steelmaking process with electricity as energy source.
This kind of steelmaking furnace includes electric arc furnace, induction furnace, electroslag furnace, electron beam furnace, consumable electric arc furnace, etc. Generally speaking, EAF steel is produced by alkaline EAF.
Electric furnace steel is mostly used to produce high-quality carbon structural steel, tool steel and alloy steel. This kind of steel has excellent quality and uniform properties. At the same carbon content, the strength and plasticity of electric furnace steel are better than those of open-hearth steel.