Raw Materials | Iron Ores

Iron ore and coke that is cooking or metallurgical coal, are the two most important raw material required for iron production. In the alternative method of iron products are cheap substitute of coke is used as a fuel depending upon its availability. The smelting operation generally requires external flux such a lime to render the gangue associated with the ore and coke ash, which is generally siliceous in nature, fusible at the relatively low temperature so as to separate radily from the molten iron. The raw materials required for iron making are :

1. Iron ore or its prepare formed : The naturally occurring materials containing iron are known as minerals of iron. The mineral deposits from which iron can be extracted economically are referred to as iron ore
2. Coking coal or coke.
3. Limestone.
4. Dolomite.
Manganese ore or its subsidiaries ore.
5. Air

Minerals of Iron :

The iron ore is not generally found in native state exception the masses of meteoric origin and in that it is usually associated with Nickel and Cobalt. Native iron rarely, is found in eruptive rocks. The red colour of soil is due to the presence of iron.

Oxides.............................Hematite and magnetite
Hydroxide......................Limonite, goethite, etc.
Carbonates....................Siderities, spathose iron, etc.
Sulphide.........................Pyrite and pyrrhotite.
Complex......................... Ilmenite, silicate etc.
Iron ore
Iron ore

Hematite :

This is the economic iron bearing mineral which has probably the widest distribution in world. It is weekly magnetic but exists a variety known as magnetite or Fe2O3 which is magnetic and is found in many Ore bodies but in small amounts.

Magnetite :

This is the second most widely spread economic iron bearing mineral in the world. It is rare tha a hematite body does not contain a few percent of magnetite and vice versa. As the name suggest this mineral is highly magnetic and as such occupied a particular place in iron ore treatment.

Goethite and Limonite :

This generally occurs as a cap on the original iron bearing mineral body because of weathering and hence on flakes and needles occurring as intergrowth with the original constituent of the ore. These are converted to oxide by calcining. These are important economic minerals in some places.

Siderite :

The siderite deposit occur as large masses, lenses and veins in many parts of the world and have been worked for many years. Some countries still find this as good source of iron.
Iron ore extraction
Iron ore extraction

Pyrite and Pyrrhotite :

These are mainly a source of sulphur and the left over iron oxide, after sulphur recovery is a by product. In spite of the fact that the residual iron oxide is quite impure, considerable tonnage of these resides continue to be used as a cheap source of iron.

Ilmenite :

The same remarks as per pyrites apply here. This is classified as a titanium ore which is frequently associated with vanadium. The iron residue that is recovered is often as a by product. Ilmenite is isomorphous with hematite and is generally present in small quantities in most hematite ore bodies.

Silicates :

These are present in most ore bodies in varing proportions. In high grade hematite and magnetite type deposits their proportion is fairly low but they are one of the major constituent of the brown hematite deposits. The presence of silicate gives rise to the oolite structure. The oolite is a spherical nodule of 2 to 3 mm but more commonly less then 0.5mm in dia consist of concentric and radiating crystal.

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