Extraction Of Iron Ore(2)(nehru Garden)

Extraction of Iron Ore Iron is the fourth-most common element in Earth's crust, and the second-most common metal after aluminium. It is about 21% of total metal of Earth’s crust and 6.2% of total elements. It belongs to transition group of the periodic table. Its electronic configuration is 2,8,8,6,2. The element is found commonly in the Sun, asteroids, and stars. The chemical symbol for iron, Fe, comes from the Latin name for the element, ferrum. The most common ores of iron are hematite and limonite.

Three processes involved in the extraction of Iron ore, which are explained below: 1.

Concentration of ore: - First of all ore is crushed into minute particles and the crushed ore is concentrated by gravity separation method..

2. Calcination :-Concentrated ore is calcinated in a furnace. During calcinations moisture is removed. Impurities like Sulphur Changes into sulphur dioxide and Arsenic into arsenic oxide, phosphorus to phosphorous oxide, all escape out in the form of gases. Fe2O3.3H2O 2FeCO3 4Fe + 3O2

Fe2O3

+ 2FeO

3H20 +

2CO2

2Fe2O3

It is due to the presence of some ferrous carbonate that iron changes into oxide. Ferrous carbonate which is present in some quantity in hematite not only oxidizes all other impurities into its oxides but also oxidized itself into iron oxide. 3.

Smelting :-Iron oxide is reduced with carbon. Process of smelting is done in blast furnace which is shown in figure.

Calcinated iron oxide is added in blast furnace along with coke. Coke serves as fuel as well as reducing agent. Lime is also added in the blast furnace which serves as flux. The following reactions take place in the furnance: FIGURE FOR THE BLAST FURNACE

1

(a) At the base of the furnace: Coke reacts with oxygen to produce Carbon dioxide which moves up and lot of heat is produced. C Coke

+

O2 Oxygen

CO2 Carbon dioxide

As the carbon dioxide moves upward it is brought in contact with coke and gets converted into carbon monoxide. C02 + Carbon Dioxide

C Coke

1475-1575K

2CO Carbon Monoxide

(b) In the middle of the furnace :In the middle of the furnace temperature is 1075 to 1275 k. In this region calcium carbonate decomposes to produce calcium oxide and carbon dioxide. Calcium oxide so produced combines with silica to form slag. CaCO3 Calcium Carbonate Dioxide CaO Calcium Oxide

+

1075-1275 K

SiO2 Silica

CaO Calcium oxide

+

CaSiO3 Calcium Silicate (Slag)

2

CO2 Carbon

(c)

At the top portion of the furnace :- In the top portion of furnace the Iron(III) oxide react with carbon monoxide to give liquid iron which moves towards the button of furnace and settled there. This iron is called cast iron.

Fe2O3 Ferric oxide

+ 3CO Carbon Monoxide

Fe + CO2 Iron Carbon dioxide

3