Extraction of metals

Question 1

What are added to the top of the blast furnace

Answer 1

Haematite, coke and limestone

Question 2

Production of carbon monoxide

Answer 2

As the carbon dioxide rises up the furnace, it reacts with more coke to form carbon monoxide.

Question 3

Production of carbon dioxide

Answer 3

The carbon in coke burns in a blast of hot air to produce carbon dioxide. This reaction produces a lot of heat.

Question 4

Haematite is reduced to iron

Answer 4

The carbon monoxide reduces the iron(III) oxide in haematite to iron.
The iron formed is molten and runs to the bottom of the furnace.

Question 5

Impurities are removed

Answer 5

Limestone (calcium carbonate) is decomposed by heat to produce carbon dioxide and calcium oxide (quicklime).
Calcium oxide is a basic oxide. It reacts with silicon dioxide, which is acidic, and with other impurities in haematite, to form molten slag (calcium silicate).
Hot waste gases containing carbon monoxide, carbon dioxide and nitrogen to escape through the top of the furnace.
The molten slag runs to the bottom of the furnace. It floats on top of the molten iron. The slag and iron are tapped off separately.