Metals & Alloys for 2nd Semester Jharkhand Polytechnic

Metals and Alloys by

Metals and Alloys by Polytechnic Walle

Metals

Definition of Metallurgy:

The process of extraction of metal from its ore and refining it is called metallurgy.

Common steps involved in the metallurgical operation are:

• Preliminary treatment of ore
• Reduction of concentrated ore
• Refining

Preliminary Treatment:

Preliminary treatment of the involves following steps:

• crushing or grinding of the ore
• concentration
• conversion of or into suitable form

Terms Involved in Metallurgy

Some important terms used in Metallurgy are discussed below.

1. Minerals: The compounds of metal found naturally in the Earth’s crust.
2. Ores: Minerals from which metal can be conventionally and economically extracted.
3. Gangue or Matrix: The unwanted impurity in the or such a mud, stone, sand, etc.
4. Leaching: Process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within into soluble salts while the impurity remains insoluble.
5. Smelting: The extraction of metal from its ore by a process involving heating and melting. (Reduction of the ore  in blast furnace)
6. Matte: Matte is a term used for molten metal sulphides formed during smelting of copper, nickel and iron ores.
7. Roasting: The heating of ore to convert impurities into oxides and the ore to its oxide form.
8. Calcination: The roasting of ore in a limited supply of air to remove volatile impurities and make the earth forest to increase its surface area.

Metallurgy of Iron

Selection of Iron Ore

• iron ore available from mines should be rich in metallic iron content
• mind should be located suitably in both ways geographically and geologically
• treatment & preparation to be given to the iron ore to make them suitable for the brass furnace service simple and cheap

Important Ores of Iron

The important commercial varieties of iron ore which are commonly used in manufacturing process are as follows:

1. Haematite
2. Limonite
3. Magnetite
4. Pyrite
5. Siderite

Haematite:

• Red Oxide of Iron
• Chemical Composition Fe₂O₃
• Contain 65-70% Iron
• Specific Gravity varies from 4.50 to 5.30
• Appearance/Colour- iron black or steel grey
• Available in India at Mysore & MP
• Other countries- England, USA, Germany, France

Limonite:

• Brown Haematite
• Chemical Composition 2Fe₂O₃•3H₂O
• Contains 60% Iron
• Specific Gravity varies from 3.60 to 4.00
• Appearance/Colour- Brown, yellowish brown or yellow
• Available in India at Jamshedpur
• Other countries- England and Spain

Magnetite:

• Black Oxide of Iron
• Chemical Composition Fe₃O₄
• Contains 70-73% Iron
• Specific Gravity varies from 4.90 to 5.20
• Appearance/Colour- Black
• Available in India at Madras (Chennai)
• Other countries- Sweden, Russia, Canada, Ireland, Norway and USA

Pyrite:

• Sulphide of Iron
• Chemical Composition FeS₂
• Contains 45-47% Iron
• Specific Gravity varies from 4.80 to 5.10
• Appearance/Colour- Bronze Yellow or Pale Brass Yellow
• Available in almost all parts of the world.
• Not adopted in iron manufacturing because of the higher percentage of sulphur present in it which makes it brittle.

Siderite:

• Carbonate of Iron
• Chemical Composition FeCO₃
• Contains 40% Iron
• Specific Gravity varies from 3.70 to 3.90
• Appearance/Colour- Pale Yellow, Brownish Red or Brownish Black
• Available in India at Raniganj, Bengal.
• Other countries- England, Russia

Resources of Iron(Fe) in India

India has certain advantages for the production of iron, since it is rich in all the three raw material (iron ore, coke, and limestone)

Orissa, Bihar, MP, Mysore, Maharashtra, Goa, Andhra Pradesh, Tamil Nadu, Uttar Pradesh, Punjab

Impurities in Ores

• Silica & Alumina in iron ore reduce iron content in ore and increase the cost of production of iron & steel
• CaCO3 or MgCO3 in the gangue decrease the amount of flux and reduce cost of production of steel

In Iron Ore Sulphur & Phosphorus are always present as impurity in the form of FeS, CaSO4, Ca3(PO4)2

• Sulphur can be removed in the blast furnace slag but cost of production is high because of the increase in the amount of flux & fuel cost.
• Sometimes sulphur is removed by sintering.
• Phosphorus can’t be removed in the slag.

Extraction of Iron (Fe)

Iron is extracted especially from magnetite, haematite and limonite ores. Following steps are involved in Extraction of Iron:

1. Concentration of Ore
2. Calcination and Roasting
3. Smelting

Concentration of Ore

• This is done by the gravity process. 
• Ore is crushed to small pieces and washed with water to remove silicious impurities. 
• Washed ore is then subjected to electromagnetic separation.

Calcination and Roasting

WalleMetalsDefinition of Metallurgy:The process of extraction of metal from its ore and refining it is called metallurgy.Common steps involved in the metallurgical operation are:Preliminary treatment of oreReduction of concentrated oreRefiningPreliminary Treatment:Preliminary treatment of the involves following steps:crushing or grinding of the oreconcentrationconversion of or into suitable formTerms Involved in MetallurgySome important terms used in Metallurgy are discussed below.Minerals: The compounds of metal found naturally in the Earth’s crust.Ores: Minerals from which metal can be conventionally and economically extracted.Gangue or Matrix: The unwanted impurity in the or such a mud, stone, sand, etc.Leaching: Process widely used in extractive metallurgy where ore is treated with chemicals to convert the valuable metals within into soluble salts while the impurity remains insoluble.Smelting: The extraction of metal from its ore by a process involving heating and melting. (Reduction of the ore in blast furnace)Matte: Matte is a term used for molten metal sulphides formed during smelting of copper, nickel and iron ores.Roasting: The heating of ore to convert impurities into oxides and the ore to its oxide form.Calcination: The roasting of ore in a limited supply of air to remove volatile impurities and make the earth forest to increase its surface area.Metallurgy of IronSelection of Iron Oreiron ore available from mines should be rich in metallic iron contentmind should be located suitably in both ways geographically and geologicallytreatment & preparation to be given to the iron ore to make them suitable for the brass furnace service simple and cheapImportant Ores of IronThe important commercial varieties of iron ore which are commonly used in manufacturing process are as follows:HaematiteLimoniteMagnetitePyriteSideriteHaematite:Red Oxide of IronChemical Composition Fe2O3Contain 65-70% IronSpecific Gravity varies from 4.50 to 5.30Appearance/Colour- iron black or steel greyAvailable in India at Mysore & MPOther countries- England, USA, Germany, FranceLimonite:Brown HaematiteChemical Composition 2Fe2O3•3H2OContains 60% IronSpecific Gravity varies from 3.60 to 4.00Appearance/Colour- Brown, yellowish brown or yellowAvailable in India at JamshedpurOther countries- England and SpainMagnetite:Black Oxide of IronChemical Composition Fe3O4Contains 70-73% IronSpecific Gravity varies from 4.90 to 5.20Appearance/Colour- BlackAvailable in India at Madras (Chennai)Other countries- Sweden, Russia, Canada, Ireland, Norway and USAPyrite:Sulphide of IronChemical Composition FeS2Contains 45-47% IronSpecific Gravity varies from 4.80 to 5.10Appearance/Colour- Bronze Yellow or Pale Brass YellowAvailable in almost all parts of the world.Not adopted in iron manufacturing because of the higher percentage of sulphur present in it which makes it brittle.Siderite:Carbonate of IronChemical Composition FeCO3Contains 40% IronSpecific Gravity varies from 3.70 to 3.90Appearance/Colour- Pale Yellow, Brownish Red or Brownish BlackAvailable in India at Raniganj, Bengal.Other countries- England, RussiaResources of Iron(Fe) in IndiaIndia has certain advantages for the production of iron, since it is rich in all the three raw material (iron ore, coke, and limestone)Orissa, Bihar, MP, Mysore, Maharashtra, Goa, Andhra Pradesh, Tamil Nadu, Uttar Pradesh, PunjabImpurities in OresSilica & Alumina in iron ore reduce iron content in ore and increase the cost of production of iron & steelCaCO3 or MgCO3 in the gangue decrease the amount of flux and reduce cost of production of steelIn Iron Ore Sulphur & Phosphorus are always present as impurity in the form of FeS, CaSO4, Ca3(PO4)2Sulphur can be removed in the blast furnace slag but cost of production is high because of the increase in the amount of flux & fuel cost.Sometimes sulphur is removed by sintering.Phosphorus can’t be removed in the slag.Extraction of Iron (Fe)Iron is extracted especially from magnetite, haematite and limonite ores. Following steps are involved in Extraction of Iron:Concentration of OreCalcination and RoastingSmeltingConcentration of OreThis is done by the gravity process. Ore is crushed to small pieces and washed with water to remove silicious impurities. Washed ore is then subjected to electromagnetic separation.Calcination and Roasting