Question: Why is hot air blown into the bottom of the blast furnace?

Lindy Heath answered on 15 Jun 2012:

The blast furnace is used to extract iron from its ore. The iron ore, coke and limestone are fed into the top and the hot air is blown into the bottom. The hot air rises through the furnace and causes several chemical reactions to happen. The oxygen in the air reacts with the coke to produce carbon dioxide and the limestone breaks down also forming carbon dioxide. This carbon dioxide will then react with more coke to form carbon monoxide. The carbon monoxide then reacts with the iron ore to extract the iron as molten iron.