EXTRACTION OF IRON

            The following raw materials are involved in manufacturing of iron:

ØIron ores (magnetite, hematite) – iron oxides with earth impurities;

ØCoke, which is both reducing agent and fuel, providing heat for melting the metal and slag.

ØCoke is produced from coking coals by heating them away from air.

ØLimestone – calcium silicate fluxes, forming a fluid slag for removal gangue from the ore.

ØIron is produced in a blast furnace, schematically shown in the picture. 

Blast furnace:-

ØIt the shaft-type furnace consisting of a steel shell lined with refractory bricks.

ØThe top of the furnace is equipped with the bell-like or other        system, providing correct charging and distribution of the raw   materials (ore, coke, limestone). 

ØAir heated to 2200°F (1200°C) is blown through the tuyeres at the bottom.

ØOxigencontaining in air reacts with the coke, producing carbon monoxide:

Ø2C + O2= 2CO

ØHot gases pass up through the descending materials, causing reduction of the iron oxides to iron according to the follwing reactions:

Ø3Fe2O3 + CO = 2Fe3O4 + CO2

ØFe3O4 + CO = 3FeO + CO2

ØFeO + CO = Fe + CO2

ØIron in form of a spongy mass moves down and its temperature reaches the melting point at the bottom regions of the furnace where it melts and accumulates.

ØThe gangue, ash and other fractions of ore and coke are mixed by fluxes, formig slag which is capable to absorb sulphure and other impurities.

ØThe furnace is periodically tapped andthe melt (pig iron) is poured into ladles, which are transferred to steel making furnaces.

ØPig iron usually contains 3-4% of carbon, 2-4% of silicon, 1-2% of manganese and 1-1.2% of phosphorous.