Extraction of iron
Iron is extracted from its oxide ores. The ores are crushed and concentrated by gravity method. Magnetite is further concentrated by magnetic method. The concentrated ore is calcined to remove volatile impurities and make the ore porous. The calcined ore contains SiO 2 as the chief impurity. It is mixed with lime stone (CaCO 3 ) as flux and coke as reducing agent and the mixture is charged into a blast furnace (a very tall steel tower lined inside with fire bricks). The charge is heated by a hot blast of air preheated at 1000 K blown in through narrow pipes (tuyers) at the base of the furnace. Here coke burns producing heat and temperature rise to 2100 K. C + O 2 --------------> CO 2 + heat The temperature falls to 500 K towards the top of the furnace due to the endothermic reaction. CO 2 + C ---------------> 2CO - heat Carbon monoxide reduces iron oxide to iron in the middle and upper regions of the furnace. 3Fe 2 O 3 + CO -----------------> 2Fe 3 O 4...