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Saturday, 14 February 2015

Raw Materials for Steel ?

Trained Engineers - 09:25

Main Contents of Raw Material
  1. Iron ore
  2. Coal and coke
  3. Lime Stone

Iron ore

Iron ores are rocks and minerals from which metallic iron can be economically extracted. The ores are usually rich in iron oxides and vary in color from dark grey, bright yellow, deep purple, to rusty red.

Key raw materials needed in steel making include iron ore, coal, limestone and recycled steel (scrap). The two main steel production routes and their related inputs are:

•The integrated steelmaking route, based on the blast furnace (BF) and basic oxygen furnace (BOF), uses raw materials including iron ore, coal, limestone and recycled steel. On average, this route uses 1,400 kg of iron ore, 770 kg of coal, 150 kg of limestone, and 120 kg of recycled steel to produce a tonne of crude steel.
• The electric arc furnace (EAF) route, based on the EAF, uses primarily recycled steels and/or direct reduced iron (DRI) and electricity. On average, the recycled steel-EAF route uses 880 kg of recycled steel, 150 kg of coal and 43 kg of limestone to produce a tonne of crude steel.
Other metals used in smaller amounts :-
–In all or most steels : manganese, silicon
–In some steels : nickel, chromium, zinc and tin
– Minor alloying elements : molybdenum, vanadium and tungsten
The iron itself is usually found in the form of magnetite (Fe3O4), hematite (Fe2O3), goethite(FeO(OH)), limonite (FeO(OH).n(H2O)) or siderite (FeCO3).

Ores carrying very high quantities of hematite or magnetite (greater than ~60% iron) are known as "natural ore" or "direct shipping ore", meaning they can be fed directly into iron-making blast furnaces. Most reserves of such ore have now been depleted. Iron ore is the raw material used to make pig iron, which is one of the main raw materials to make steel. 98% of the mined iron ore is used to make steel.Indeed, it has been argued that iron ore is "more integral to the global economy than any other commodity, except perhaps oil".

Steel is an alloy consisting mostly of iron and less than 2% carbon. Iron ore is, therefore, essential for the production of steel, which in turn is essential in maintaining a strong industrial base. 98% of mined iron ore is used to make steel. Iron is one of the most abundant metallic elements. Its oxides, or ores, compose about 5% of the earth’s crust. Average iron content for ores is 60% to 65%, after taking into account other naturally-occurring impurities.
• Iron ore is mined in about 50 countries. The majority of iron ore is mined in Brazil, Australia, China, India, the US and Russia. Australia and Brazil together dominate the world’s iron ore exports, each having about one-third of total exports.

• Worldwide iron ore resources are estimated to exceed 800 billion tonnes of crude ore, containing more than 230 billion tonnes of iron.

• Current reserves (extractable using available technology) of iron ore are estimated at 180 billion tonnes. If potential reserves are included, this increases to 370 billion tonnes.

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