Describe the process of iron extraction in a blast furnace, including its raw materials, reactions, and the properties of the resulting iron.

a) The constituents of A (the raw materials fed into the blast furnace) are iron ore, coke, and limestone.

b) You would expect the highest temperature at point R, which is at the bottom of the furnace where the hot air blast enters and coke combustion occurs most intensely.

c) The role of the hot air blast is to:

• Provide oxygen for the combustion of coke (carbon) to produce heat and carbon dioxide.
• The carbon dioxide then reacts with more hot coke to produce carbon monoxide, which acts as the main reducing agent for the iron ore.

d) Yes, it is possible to separate iron from the slag. This is because molten iron and molten slag are immiscible (do not mix) and have different densities. The slag is less dense than the molten iron, so it floats on top and can be tapped off separately.

e) The main reaction that takes place to produce iron is the reduction of iron(III) oxide by carbon monoxide:

$$\text{Fe}_2\text{O}_3\text{(s)} + 3\text{CO(g)} \to 2\text{Fe(l)} + 3\text{CO}_2\text{(g)}$$

f) Iron obtained from the furnace (pig iron) contains about 4% carbon and other impurities, making it hard and brittle. For making bridges, which require materials that are strong, tough, and ductile, pig iron must be further treated to remove most of these impurities and convert it into steel.

g) Galvanized iron is iron or steel that has been coated with a protective layer of zinc.

h) It is necessary to galvanize iron to prevent it from rusting (corrosion). The zinc coating acts as a physical barrier and also provides sacrificial protection, corroding preferentially to iron if the coating is scratched.

i) One environmental hazard associated with the extraction of iron is air pollution, specifically the release of carbon dioxide (a greenhouse gas) and sulfur dioxide (which contributes to acid rain) from the combustion of coke and impurities.