The fourth most common element in the earth crust is Iron. Just Like aluminum, most iron are found in bound condition inside the Earth exists in the form of oxides. Iron oxides exist in seven main ores (raw, rocky minerals mined from Earth):
Different ores contain different amounts of iron :_
- Hematite and magnetite have about 70 percent iron
- limonite has about 60 percent
- pyrite and siderite have 50 percent
- taconite has only 30 percent
Types of iron
Pure iron is too soft and reactive to be of much real use. That is the reason iron is mixed with other elements (especially carbon) to make stronger, more resilient forms of the metal including steel. Broadly speaking, steel is an alloy of iron that contains up to about 2 percent carbon, while other forms of iron contain about 2–4 percent carbon.
Pig iron (Impure form of Iron)
Basic raw iron is called pig iron because it’s produced in the form of chunky molded blocks known as pigs.The iron made in a blast furnace is an alloy containing about 90–95 percent iron, 3–4 percent carbon, and traces of other elements such as silicon, manganese, and phosphorus, depending on the ore used. Pig iron is much harder than 100 percent pure iron, but still too weak for most everyday purposes.we can say pig iron is brittle and having no ductile properties
Cast iron (Cast iron contains about 2 to 4 percent of carbon)
Cast iron is simply liquid iron that has been cast: poured into a mold and allowed to cool and harden to form a finished structural shape, such as a pipe, a gear, or a big girder for an iron bridge. The high carbon content of cast iron (the same as pig iron—roughly 3–4 percent) makes it extremely hard and brittle: large crystals of carbon embedded in cast iron stop the crystals of iron from moving about. Cast iron has two big drawbacks: first, because it’s hard and brittle, it’s virtually impossible to shape, even when heated; second, it rusts relatively easily.
Wrought iron (it hardly contains carbon more than 0.15 percent)
Wrought iron is the purest form of iron . Wrought iron is softer than cast iron and much less tough, so you can heat it up to shape it relatively easily, and it’s also much less prone to rusting.