Iron Extraction: Blast Furnace

Pig iron: Collected at bottom (~4% C, brittle)
Slag (CaSiO3): Floats above iron, tapped separately

Charging from top: Haematite (Fe2O3) + Coke (C) + Limestone (CaCO3) Hot air blast from bottom: Maintains temperature gradient

Zone	Temperature	Main Reaction
Combustion zone (bottom)	~2000 K	$C + O_2 \rightarrow CO_2$
CO formation	~2000 K	$CO_2 + C \rightarrow 2CO$
Flux zone (middle)	~1400 K	$CaCO_3 \rightarrow CaO + CO_2$ ; $CaO + SiO_2 \rightarrow CaSiO_3$
Reduction zone (upper)	500–800 K	$Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2$

$3Fe_2O_3 + CO \rightarrow 2Fe_3O_4 + CO_2$ $Fe_3O_4 + CO \rightarrow 3FeO + CO_2$ $FeO + CO \rightarrow Fe + CO_2$

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