-AHAN M R

10 –B (25)

SOME IMPORTANT TERMS-

NOTE-Minerals: A solid element or compound which occurs naturally in the Earth's crust is called a mineral.Ore: A mineral from which metals can be extracted profitably is called a metal ore. Profitable extraction means that the cost of getting the metal out of the ore is sufficiently less than the amount of money made by selling the metal. So All Ores Are Minerals But All Minerals Are Not Ores.The most common metal ores are oxides and sulphides. Metals are obtained from their ores by reduction.

What is a Blast furnace??

It is a tall cylindrical furnace made of steel.

It is lined inside with fire bricks.

It is narrow at the top and has an arrangement for the introduction of ore and outlet for waste gases.

Heated with help of Hot Gases.

What are the functions of a Blast Furnace???

• The function of a blast furnace is to reduce and convert iron oxides into liquid iron called "hot metal".

• The blast furnace is a huge, steel stack lined with refractory brick.

• Iron ore, coke and limestone are put into the top, and preheated air is blown into the bottom.

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Steps involved in Blast furnace --

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10-B Ahan M R

Steps of Iron Extraction in Blast furnace-

• Step 1-Insert iron ore, limestone, and coke into blast furnace.

• Step 2-Coke reacts with oxygen and forms carbon dioxide- C(s)+O2(g) --> CO2(g).

• Step 3-Limestone decomposes and forms another carbon dioxide- CaCO3(s) --> CO2(g)+CaO(s).

10-B Ahan M R

Steps of Iron Extraction in Blast furnace-

• Step 4-Carbon dioxide produced in the first 2 reactions reacts with excess coke and forms carbon monoxide-CO2(g)+C(s) --> 2CO(g).

• Step 5-Carbon monoxide reduces iron ore and produces molten iron- 3CO(g)+Fe2O3(s) --> 2Fe(l)+3CO2(g).

10-B Ahan M R

Steps of Iron Extraction in Blast furnace-

• Step 6-The excess limestone from the second reaction reacts with the sand (coming from minerals in iron ore) and forms calcium silicate (slag) - CaO(s)+SiO(s) --> CaSiO3(l).

• Step 7-Slag and molten iron are drained from the bottom of the furnace and gas produced exits through holes in the top of the furnace

Step 3 - Limestone decomposes and forms another carbon dioxide- CaCO3(s) --> CO2(g)+CaO(s)

Step 4 - Carbon dioxide produced in the first 2 reactions reacts with excess coke and forms carbon mono xide-CO2(g)+C(s) --> 2CO(g).

Step 2 - Coke reacts with oxygen and forms carbon dioxide- C(s)+O2(g) --> CO2(g).

Step 6 - The excess limestone from the second reaction reacts with the sand (coming from minerals in iron ore) and forms calcium silicate (slag) -CaO(s)+SiO(s) --> CaSiO3(l).

Step 1 - Insert iron ore, limestone, and coke into blast furnace.

Step 7 - Slag and molten iron are drained from the bottom of the furnace and gas produced exits through holes in the top of the furnace .

Step 5 - Carbon monoxide reduces iron ore and produces molten iron- 3CO(g)+Fe2O3(s) --> 2Fe(l)+3CO2(g).

SUMMARY -

Why does Iron have to be extracted in a Blast Furnace???

• Iron has to be extracted by the blast furnace because it contains mud ,clay ,minerals , mixture of other metals and some unwanted materials.

• In the furnace ,the iron is be displaced by carbon.

• This is more efficient method than electrolysis because it is more cost effective.

1. HOW DOES A BLAST FURNACE LOOK???

2. WHAT KIND OF CHEMICAL REACTIONS TAKE PLACE IN A

BLAST FURNACE???

LETS FIND IT OUT !!!

Three substances are needed to enable to extraction of iron from its ore. The combined mixture is called the charge:

Iron ore, haematite - often contains sand with iron oxide, Fe2O3.

Limestone (calcium carbonate).

Coke - mainly carbon

The charge is placed a giant chimney called a blast furnace. The blast furnace is around 30 metres high and lined with fireproof bricks. Hot air is blasted through the bottom.

The Method

• Oxygen in the air reacts with coke to give carbon dioxide:

C(s) + O 2(g) CO2(g)

• The limestone breaks down to form carbon dioxide:

CaCO3(s) CO2 (g) + CaO(s)

• Carbon dioxide produced in 1 + 2 react with more coke to produce carbon monoxide:

CO2(g) + C(s) 2CO(g)

Several reactions take place before the iron is finally produced...

•The carbon monoxide reduces the iron in the ore to give molten iron:

3CO(g) + Fe2O3(s) 2Fe(l) + 3CO2(g)

•The limestone from 2, reacts with the sand to form slag (calcium silicate):

CaO(s) + SiO(s) CaSiO3(l)

• Both the slag and iron are drained from the bottom of the furnace.

• The slag is mainly used to build roads.

• The iron whilst molten is poured into moulds and left to solidify - this is called cast iron and is used to make railings and storage tanks.

• The rest of the iron is used to make steel.

Products formed -

COMMERCIAL FORMS OF IRON-There 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 other impurities like Sulphur, Phosphorus, Manganese etc.

2. Wrought IronIt is the purest form of Iron and contains carbon to the extent of 0.25%.

3. SteelIt contains 0.5 to 1.5 % of carbon along with varying amount of other elements.