Introduction

The blast furnace is essentially a continuous counter-current reactor in which the descending charge is heated and reacted with ascending gases, derived from combustion of carbon at the tuyere. The charge consists of iron sinter/pellets + coke and limestone. During descent, iron oxide is reduced to FeO and limestone decomposed to CaO and CO₂.

The combustion of coke at the tuyere level with air raises the temperature in between   and melts slag and metal.

The reduction of FeO to Fe and the melting of iron and formation of hot metal and slag begin once the charge descends to the bosh region. The following reduction reactions occur:

 

 

 

 

The gases consisting mainly of  and  and some, derived from moisture of blast, ascends through the charge. Heat transfer occurs as the gas rising upward and simultaneously reduction of wustile to  occurs.The  so produced quickly reacts with C and produces   

Further reaction between CO and higher oxides of iron will produce  which accumulates in the ascending gases. The content of  increases with the decomposition of  
                                              .
at about . The exit gas may contain  ratio close to one and leaves the furnace at about 500-600K.