Select the correct statement(s) about the iron blast furnace.

AIn the cooler upper region, carbon monoxide reduces $Fe X_{2} O X_{3}$ partly to $Fe X_{3} O X_{4}$ ( $3 Fe X_{2} O X_{3} + CO 2 Fe X_{3} O X_{4} + CO X_{2}$ )
BThe $CO X_{2}$ formed by burning coke near the tuyeres is reduced to $CO$ by hot coke higher up the furnace
CThe molten slag is denser than molten iron and collects below it
DLimestone decomposes to $CaO$ and $CO X_{2}$ , and $CaO$ combines with silica to form the slag $CaSiO X_{3}$

Answer: A, B, D

Fe(III) is reduced stepwise by CO as the gases rise through cooler zones, so the first statement is true. Limestone calcines to

CaO

which fluxes

SiO X_{2}

(true). The slag is lighter than molten iron, floats on it and is tapped separately, so statement 3 is false. At the hot zone

CO X_{2} + C 2 CO

regenerates the reducing gas (true).