Extraction Of Iron

• 1. Extraction ofIron Designed By: Nawaraj Kumar MahatoCOBASS +2 Science

2. As History Tells UsStone Age and Bronze Age:Humans have used metals for thousands of years.Gold and silver, found as native metal, were used asjewellery. These metals were known in the Stone Age butgold and silver are too soft to be used as tools. The firstreally useful metallic alloy to be discovered was bronze inthe Bronze Age. Bronze is not an element (like gold andsilver) but an alloy (metal mixture) of copper and tin.Bronze was used extensively for tools and weapons. 3. As History Tells UsIron Age: After the Bronze Age came the Iron Age.People discovered that a high temperature coalfire could be used for the extraction of iron fromiron ore. The discovery of electricity at thebeginning of the nineteenth century allowed theextraction of the more reactive metals.Aluminium has been extracted on a large scalesince about 1870. 4. Some Terms Lets Have a LookMinerals: A solid element or compound whichoccurs naturally in the Earths crust is called amineral.Ore: A mineral from which metals can be extractedprofitably is called a metal ore. Profitable extractionmeans that the cost of getting the metal out of theore is sufficiently less than the amount of moneymade by selling the metal. So All Ores Are MineralsBut All Minerals Are Not Ores.The most common metal ores are oxides andsulphides. Metals are obtained from their ores byreduction. 5. Be Aware!!Metal ore deposits are a finite resource (there areonly a certain amount of them) and non-renewable(once used, they are gone and will not bereplaced). Many metals are obtained today fromrecycling (melting and refining) scrap metals.Native Metals: Gold and platinum occur in theEarth as native metal, which means that they arefound as the element, not the compound, and so donot need to be reduced. Silver and copper may alsobe found as native metal. 6. Occurrence of IronIron is very reactive and is found in nature in form ofits oxides, carbonates and sulphates. The mainores are:i) Haematite (Fe2O3)ii) Magnetite (Fe3O4)iii) Iron Pyrites (FeS2)o The main iron ore is Haematite (iron (III) oxide -Fe2O3).o The iron ore contains impurities, mainly silica(silicon dioxide).o Since iron is below carbon in the reactivity series,iron in the ore is reduced to iron metal by heatingwith carbon (coke). 7. Extraction of IronStep1: ConcentrationThe ore is crushed in crushers and isbroken to small pieces. It is concentrated withgravity separation process in which it iswashed with water to remove clay, sand, etc. 8. Steps of ExtractionStep1: ConcentrationStep2: Calcination The ore is then heated in absence of air(calcined). This results in decomposition of carbonatesinto oxides and then ferrous oxide is converted intoFerric Oxide.FeCO3 FeO CO 24FeO O2 2Fe2CO3 9. Steps of ExtractionStep1: ConcentrationStep2: CalcinationStep3: SmeltingThe concentrated ore is mixed withcalculated quantity of coke, limestone and themixture is put in the Blast Furnace from top. 10. Blast Furnace It is a tall cylindrical furnacemade of steel. It is lined inside with firebricks. It is narrow at the top and hasanarrangement fortheintroduction of ore and outlet forwaste gases. Heated with help of Hot Gases. 11. Chemical ReactionsFollowing Chemical Reactions Take Place in aBlast Furnacei) Formation of Carbon Monoxide:Near the bottom of the furnace, coke burns in air toform Carbon Dioxide and a lot of heat is produced.We get a temperature of about 1875 K.This CO2 further reacts with more coke and isreduced to CO. C O2 CO2 Heat C CO22CO 12. Chemical Reactionsii) Reduction of Haematite to Iron:In the upper part of the furnace, the temperature isbetween 975K to 1075K. Here Haematite isreduced to Iron by CO. This molten Iron iscollected at the bottom of the furnace. Fe 2 O3 3CO2Fe 3CO 2 13. Functions of Limestone1.It acts as flux to remove sand from Haematite in formof liquid Slag. In the middle of the furnace, thetemperature is about 1075-1275 K. Here Limestonedecomposes to produce calcium oxide (CaO) andCO2.This CaO reacts with reacts with silica (sand)present in the ore to form slag(CaSiO3).CaCO3 heatCaO CO 2CaO SiO 2 CaSiO 32.Slag is lighter than molten iron so it floats overmolten iron and protects it from oxidising back into itsoxides. 14. Commercial Forms of IronThere are three major commercial forms of Iron.They differ in their carbon content.1. Cast Iron (or Pig Iron)It contains 2-5% Carbon along with traces of otherimpurities like Sulphur, Phosphorus, Manganeseetc.2. Wrought IronIt is the purest form of Iron and contains carbon tothe extent of 0.25%3. SteelIt contains 0.5 to 1.5 % of carbon along with varyingamount of other elements. 15. Testing Zone..Match the following:a) Haematite a) Extraction of Ironb) Calcination b) Ore of Ironc) Smeltingc) CaSiO3d) Slagd) Acts as Fluxe) Lime Stonee) Type of Iron f) Heating in absence of air. 16. Testing Zone..Match the following:a) Haematite a) Extraction of Ironb) Calcination b) Ore of Ironc) Smeltingc) CaSiO3d) Slagd) Acts as Fluxe) Lime Stonee) Type of Iron f) Heating in absence of air. 17. Testing Zone..Match the following:a) Haematite a) Extraction of Ironb) Calcination b) Ore of Ironc) Smeltingc) CaSiO3d) Slagd) Acts as Fluxe) Lime Stonee) Type of Iron f) Heating in absence of air. 18. Testing Zone..Match the following:a) Haematite a) Extraction of Ironb) Calcination b) Ore of Ironc) Smeltingc) CaSiO3d) Slagd) Acts as Fluxe) Lime Stonee) Type of Iron f) Heating in absence of air. 19. Testing Zone..Match the following:a) Haematite a) Extraction of Ironb) Calcination b) Ore of Ironc) Smeltingc) CaSiO3d) Slagd) Acts as Fluxe) Lime Stonee) Type of Iron f) Heating in absence of air. 20. Testing Zone..Match the following:a) Haematite a) Extraction of Ironb) Calcination b) Ore of Ironc) Smeltingc) CaSiO3d) Slagd) Acts as Fluxe) Lime Stonee) Type of Iron f) Heating in absence of air. 21. Testing Zone..Mark True of False1. Metals can be extracted profitably from ores.2. All minerals are ores.3. Chief ore of Iron is Iron Pyrites.4. Iron is reduced with the help of Coke.5. Slag is formed by reaction between CaCO3 and SiO2 22. Testing Zone..Mark True of False1. Metals can be extracted profitably from ores. (True)2. All minerals are ores. (False)3. Chief ore of Iron is Iron Pyrites. (False)4. Iron is reduced with the help of Coke. (True)5. Slag is formed by reaction between CaCO3 and SiO2.(False) 23. Testing Zone..Choose the right Answer out ofThe given choices:Ques1: The actual reducing agent in Blast Furnace is:A) CokeB) Carbon DioxideC) Carbon MonoxideD) Iron 24. Testing Zone..Choose the right Answer out ofThe given choices:Ques1: The actual reducing agent in Blast Furnace is:A) CokeB) Carbon DioxideC) Carbon MonoxideD) Iron 25. Testing Zone..Choose the right Answer out ofThe given choices:Ques2: The formula for Haematite is:A) FeOB) FeO2C) Fe2O3D) Fe3O4 26. Testing Zone..Choose the right Answer out ofThe given choices:Ques2: The formula for Haematite is:A) FeOB) FeO2C) Fe2O3D) Fe3O4 27. Testing Zone..Choose the right Answer out ofThe given choices:Ques3: Which is the purest form of Iron?A) Cast IronB) Wrought IronC) Pig IronD) Steel 28. Testing Zone..Choose the right Answer out ofThe given choices:Ques3: Which is the purest form of Iron?A) Cast IronB) Wrought IronC) Pig IronD) Steel 29. Do it YourselfQ 1: Name three ores of IronQ 2: Write the chemical reactions taking place in a blastfurnace during extraction of IronQ3: What are three major types of Iron. How do theydiffer from each other?Q4: Draw a neat labelled diagram of Blast Furnace. 30. Thank you Learn MoreBe Practical in Life Log on to site given below andFollow me and download this slide for FREEwww.slideshare.com/Nawarajintermediate