Elemental iron (Fe) is ranked fourth in abundance in the earth’s crust and is the major constituent of the earth’s core. It rarely occurs in nature as the native metal.
Read Here: What is Iron Ore?
The iron minerals that are at present used as ores are Hematite, Magnetite, Limonite and Siderite; also, occasionally Ankerite, Goethite and Turgite. Magnetite & Hematite is the most abundantly formed Iron Ore.
Hematite ore is a direct-shipping ore with naturally high iron content. Because of its high iron content, hematite ore must undergo only a simple crushing, screening and blending process before being shipped off for steel production.
Hematite ore is found in abundance throughout the world, but the most utilised deposits are in Brazil, Australia and Asia. Brazil is another one of the world’s main sources of hematite ore. Carajas mine is the largest iron ore mine in existence and is operated by Brazilian mining company Vale. Vale is the third-largest mining company in the world and the largest producer of iron ore pellets. Vale’s headquarters are in Rio de Janeiro, and its primary iron ore assets are in the Iron Quadrangle region of Minas Gerais.
In Asia, a great deal of mining for hematite ore is done in China. Known reserves include the Tung-Yeh-Chen hematite ore deposit and the Dongye hematite ore deposit.
The mineral magnetite actually has higher iron content than the mineral hematite. However, while hematite ore generally contains large concentrations of hematite, magnetite ore generally holds low concentrations of magnetite. As a result, magnetite ore must be concentrated before it can be used to produce steel. Magnetite ore’s magnetic properties are helpful during this process.
Magnetite ore is currently mined in Minnesota and Michigan in the US, as well as in taconite deposits in Eastern Canada. A major mining site in Michigan is the Marquette Range. The deposit was discovered in 1844, and ore was first mined there in 1848. Magnetite ore and hematite ore are among the four types of iron ore deposits found in this area.
Ankerite is a carbonate of lime, magnesia, manganese and iron. It is of valuable composition, carries only 14 or 15% of iron and is used more of its lime and magnesia as a flux than for its iron content. Goethite and Turgite come in between Hematite and Limonite in composition and are found with both, but are comparatively rare.
Limonite or Brown Ore is to be found at the bottom of some bogs and shallow lakes, in favourable situations, where the weather rocks have yielded iron to the water draining into these basins. The limonite accumulates so fast in some places that lake bottom may be cropped again after a number of years, as at Radnor Forges, Quebec, Canada.
Siderite or Spathi iron ore is usually grey or white but at the surface, it weathers to limonite, and the weathering may extend to a considerable depth. A rusty capping may cover a deposit of siderite. Where the ore forms the face of a cliff, the limonite may wash away as fast as it forms, leaving the siderite clean.