Question

At the end of basic oxygen heat, the FeO content of the slag is approximately 20% which corresponds to a mole fraction of 0.165. Assuming that the activity coefficient of FeO in the slag is unity and that the slag and finished steel are in equilibrium at 1600oC, estimate the carbon content of the metal bath. Assume dilute solution and total pressure of 1 atm.

Answer 1

Ans. In the steel making process the basic oxygen is used. In this process impurities of hot metal such as carbon (C), Silicon (Si), Manganese and similar other are removed by oxidation in the presence of higly pure oxygen. The oxidation process leads to the formation of carbon monoxide (CO), carbon dioxide (CO₂), silica (SiO₂), manganese oxid (MnO)e and iron oxides (FeO) etc.

The basic slag formation takes place during oxygen heat. At the end of oxygen heat the reactions follow the secondary oxidation -reduction reaction. This leads to decarburization process on liquid iron oxide (FeO) circulating in the slag. The basic reaction involved during slag circulation is:

.............................................................................(a)

Here we assumed the dilute solution and a total pressure of 1 atm.

Given the slag contains 20% FeO. And also given the activity coefficient of FeO in the slag is unity.

Hence the slag contains the left amount as carbon content based on (a) .

Say, C = Carbon content

%

%

Since the mole fraction of FeO is given as 0.165;

we can write as:

Say the total moles the slag contain including FeO and Carbon are = N

Hence FeO content is 20% of N

Total number of moles are 0.825; out which 80 % is the carbon at equilibrium,

Say mole fraction of carbon = X_c

Hence, the mole fraction of Carbon 0.66

In precentage the carbon content will be given 66%.

The carbon content of metal bath at 1600 ^oC will be 66%