Extraction of Iron metals, for std 11 & 12 GSEB

Furnace

Iron :
Iron been known since prehistoric times. Indians were familiar with the extraction of iron for a long time. Iron is the most useful metal industrially and hence it may be called the king of metals. It is a transition element with atomic number 26 and mass number 56. Its symbol is Fe. The electronic configuration of iron is 

Electronic configuration of Iron

Occurrence : 

Iron is the fourth abundant element in earth’s crust (5%), Most probably, the core of the earth contains solid iron under very high pressure and this is surrounded by a layer of molten metals. The ores of iron are; Haematite (Fe2O3), Magnetite (Fe2O4), Limonite (Fe2O3 H2O) and siderite (FeCO3).
Magnetite and Hematite are available in large quantities in our country.

Extraction of Iron :
Haematite is powdered and washed in a current of water to remove the unwanted earthly impurities. The earthly impurities such as sand, clay, organic wastes are called gangue. Even after removing some of the gangue materials, the ore would contain silicon dioxide as impurity.
To extract iron from haematite the following materials are needed. They are haematite ((Fe2O3), lime stone (CaCO3) and coke (C).

Furnace - Extraction of Iron process

Video for Extraction of Iron - Furnace

The concentrated haematite, limestone and coke are mixed in the ratio 8 : 1 : 4. This mixture is called charge. The mixture is introduced into the blast furnace (Fig) from the top of the furnace by the cup and cone arrangement. Hot air is blown from bottom of the furnace. The following reactions take place and finally iron is produced.

1. Lime stone decomposes to calcium oxide.

Lime stone - to calcium Oxide

Calcium oxide reacts with silica to form calcium silicate.

Calcium Oxide  reacts with Silica

2. Coke reacts with oxygen present in the air to form carbon dioxide.

Coke with oxygen form CarbonDioxide

3. Carbon dioxide reacts with more coke to produce carbon monoxide.

Carbon dioxide reacts with more Coke product Carbon Monoxide

4. Carbon monoxide reduces the iron oxide to iron.

Carbon monoxide reduces the iron oxide to Iron

Iron so produced will be in molten state and is collected at the bottom of the furnace.

Calcium silicate is a slag. It collects at the bottom of the furnace above the molten iron. The molten iron and the slag are removed from a separate outlet. Iron so obtained from the blast furnace is called cast Iron or Pig Iron.

Physical properties : 

Iron is a greyish white solid metal. Pure iron is soft. Iron is a ferromagnetic substance. Its melting point is 1808K.

Chemical properties : 

you have already learnt about a few reactions of iron with air and acids. Let us now study the chemical displacement of iron.

Experiment 7 : 

Pour some copper sulphate solution into a beaker. Suspend a new iron nail in it with the help of a thread. Examine the nail after sometime. What do you observe? Discuss with your teacher the changes that are seen.

Reaction of Iron with Copper Sulphate

Iron Nail suspend in Copper Sulphate

Experiment 8 : 

Take some silver nitrate solution in a beaker. Place a new iron nail in it. Observe the changes. Give reason for the changes that you see. The equation of the reaction can be written as follows :

Reaction of Iron with Silver nitrate Solution

Iron Nail suspend  in Silver Nitrate

From the above two experiments we can conclude that iron is more reactive than copper and silver. Hence it displaces copper from copper sulphate solution and silver from silver nitrate solution.

Alloys of Iron : 

The alloys of iron are useful. Some of the alloys, their components and uses are given here. 

Table for Alloys of Iron

POINTS TO REMEMBER 

1.Zinc, magnesium and iron react with steam to form respective oxides of the metal liberating hydrogen.
2. Magnesium, Zinc, Iron, and copper reacts with dilute hydrochloric acid liberating hydrogen and forming respective metallic chloriedes.
3. Metals produce hydrogen with very dilute nitric acid [iron is an exception] along with metallic nitrates.
4. Metals produce hydrogen with dilute sulphuric acid along with metallic sulphates.
5. Metals produce metallic chlorides with chlorine.
6. The electronic configuration of copper is
1s2 2s2 2p6 3s2 3p6 3d10 4s1
7. The ores of copper are copper pyrites, copper glance, malachite and azurite.
8. The ore of copper is concentrated by forth floatation.
9. Copper ore is mixed with sand and roasted in a furnace to obtain molten copper.
10. Copper is purified by electrolytic refining in which the pure copper plate is cathode and the impure copper plate is anode.
11. Brass, bronze german silver and gun metal are alloys of copper.
12. The electronic configuration of iron is 

       1s2 2s22p6 3s23p63d6 4s2
13.The ores of iron are haematite, magnetite, limonrite and siderite.

14. Hematite, lime stone and coke are the raw materials in the extraction of iron. 

15. Iron is extracted by blast furnace process.
16. Iron displaces copper from copper sulphate solution and silver from silver nitrate solution.
17. The alloys of iron are stainless steel, nickel steel, alnico, invar steel and nichrome.