Group presenterSonam TsheringSherab Chophel

Shreejana Bomjan

Extraction of Iron

Raw materials or ore of iron Haematite (Fe2O3), magnetite (Fe3O4)The main ore of iron is Hematite.It minerals composed of iron oxide.The extraction of iron involves the following

process-1. The concentration of ore.2. The calcinations or roasting of ore.3. The reduction of ore.

1. The concentration of ore The process of removal of impurities present in the ore is

called concentration.It involves the following process:1 washing of ore- When the density of impurities is less than

that of the ore, this method can be used. When powdered ore is washed in a stream of water, the floating impurities will be washed away and the ore will remain underneath.

2 froth floatation process- If the density of the ore is less than that of impurities this method is used. Powdered ore is added to a mixture of pine oil and water. This is stirred by a strong current of air. Pine oil forms froth and the ore wetted by pine oil floats with it.

This can be easily removed. This method is used for the concentration of sulphide ores.

Magnetic separation- If the ore is magnetic, it can be

separated from the impurities by passingthrough a magnetic field. The magnetic oreis attracted towards the magnet.

2. calcinations or roasting ore- The concentrated ore is heated in the absence of air. It is performed to remove moisture, CO2, impurities of sulphur and arsenic etc…

3.Reduction of ore in blast furnace

Step 1- the haematite (ore) is fed in the top of the furnace along with the coke ( cheap form of carbon, made form coal) and lime stone.

Step 2- the furnace is heated by the blast of hot air and combustion of coke it increase the temperature to around 1500 degree Celsius.

Step 3- coke is added to the haematite to provide reducing agent for the iron (III) oxide. Some iron (III) oxide is reduced by carbon in contact with the haematite.

The most of the iron(III) oxide is reduced by carbon-monoxide gas.

It is formed when carbon dioxide (made from coke burning in the blast of hot air) react with more hot coke.

First carbon combine with oxygen (air) to form carbon dioxide.

C (s) + O2 CO2 Then, carbon dioxide + Carbon

carbon- monoxide CO2 (g)+ C (s) 2CO

The carbon monoxide reduces iron(III) oxide; iron (III) oxide + carbon monoxide iron

+ carbon dioxide 2Fe2O3 + 3CO 4Fe + 3CO2As a result the iron form as a liquid in high

temperature inside the blast furnace. It sinks to the bottom of the furnace where it is tapped off.

The lime stone (CaCO3) is added to get rid of the sandy bits of rocks in the ore, which are acidic. The lime stone (CaCO3) is broken down into hot furnace.

Calcium carbonate calcium oxide + carbon dioxide.

CaCO3 CaO + CO2 Calcium oxide is a base, it react with silicon

dioxide (sand). CaO (s) + SiO2 (s) CaSiO3(I)

(calcium- silicate)The molten calcium silicate (slag) is float on

the top of the molten iron at the base of the furnace. Here it is tapped off and cooled to use in building purposes.

Summary Iron is extracted from its ore haematite in a

blast furnace. The ore is fed into the top of the furnace along with coke and lime stone. The main reducing agent is carbon monoxide;

Iron (III) oxide +carbon monoxide iron + carbon dioxide

2Fe2O3+ 3CO 4Fe + 3CO2The molten iron is then tapped from the bottom

of the furnace. The lime stone decomposes in the hot furnace forming calcium oxide .this reacts with the silicon dioxide to form slag.