An ingot is a mass of metal obtained from casting liquid steel into a mould. The resulting ingot - a semi-finished product - is typically then hot rolled or forged.

Integrated mills make steel by processing iron ore and other raw materials in blast furnaces. They are slightly different to mini-mills since they use hot end techniques. However, the differing technological approaches to molten steel imply different scale efficiencies and, therefore, separate management styles, labour relations, and product markets. Nearly all domestic integrated mills specialize in flat-rolled steel or plate.

Iron is a naturally occurring element which was first smelted from its ore into a tough silvery/white metal about 2,400 BC. Cast iron is hard and brittle, while wrought iron is soft and malleable. Iron from a blast furnace (pig iron) is an alloy of iron and carbon (about 4%), along with smaller quantities of silicon, manganese, phosphorus, sulphur and other elements. Iron is a far less versatile metal than steel, which is also an alloy of iron. It is produced in a BOF and has a much reduced carbon content. Other elements, particularly manganese, are adjusted or added to achieve specific properties. There are many thousand different steel grades. Even high carbon steels contain no more than about 1.5% carbon, though some high alloy steels reach 2.5%. Carbon allows hardening of the steel via heat treatment.

Iron carbide is a substitute for high-quality and low-residual scrap and is often used in electric furnace steelmaking. There are also many other substitutes. Iron carbide producers use natural gas to reduce iron ore to iron carbide.

An iron-ore is a mineral containing enough iron to be a commercially viable source of the element used in steelmaking. Except for fragments of meteorites found on earth, iron is not a free element; instead, it is trapped in the earth’s crust in its oxidized form.