Classification of iron

By use

Pig iron for steelmaking
Pig iron for steelmaking refers to the pig iron used for open hearth and converter steelmaking. Generally, the content of silicon is low (ω Si is no more than 1.75%), and the sulfur content is high (ω s is no more than 0.07%). It is the main raw material for steelmaking and accounts for 80% – 90% of the pig iron output. Steelmaking pig iron is hard and brittle with white fracture, so it is also called white cast iron

Cast pig iron
Cast pig iron refers to the pig iron used for casting various pig iron castings, commonly known as foundry iron. Generally, the silicon content is high (ω Si is up to 3.75%), and the sulfur content is slightly lower (ω s is no more than 0.06%). It accounts for about 10% of the pig iron output and is the main commercial iron in iron and steel works. Its fracture surface is gray, so it is also called gray iron

By chemical composition
Ordinary pig iron
Ordinary pig iron refers to the pig iron without other alloy elements, such as steel-making pig iron and casting pig iron
Special pig iron

Natural alloy pig iron
Natural alloy pig iron is a special pig iron made by reducing iron ore or concentrate containing associated metals such as copper, vanadium, nickel, etc. it contains a certain amount of alloy elements (one or more, determined by the composition of the ore), which can be used for steelmaking and casting

The difference between ferroalloy and natural alloy pig iron is that other ingredients are specially added during ironmaking to produce special pig iron containing various alloy elements. Ferroalloy is one of the raw materials for steelmaking and can also be used for casting. It can be used as deoxidizer and additive of alloy elements to improve the properties of steel

There are many kinds of ferroalloys, such as ferrosilicon, ferromanganese, ferrochrome, ferrotungsten, ferromolybdenum, ferrovanadium, ferrovanadium, ferroboron, ferronickel, ferroniobium, silicomanganese, rare earth alloys and so on, of which the largest amount is ferromanganese, ferrosilicon and ferrochrome. According to different production methods, ferroalloys are usually divided into blast furnace ferroalloy, electric furnace ferroalloy, extra furnace ferroalloy and vacuum carbon reduction ferroalloy