Oxidation of Silicon:

Consider reaction 2

(13)

(14)

Different sources give the following expression for                                               

(15)

                                                                    

(16)

Both equations predict that decrease in temperature increases . There is a slight difference in values of . Equation 15 predicts 15-17% higher  than equation 16.

Conditions favourable for silicon oxidation are

• Low temperature
• Low  in slag. A basic slag favours silicon oxidation.

In a basic slag, silicon oxidation occurs practically to a very low value since reacts with CaO and decreases activity of silica in slag.

Another important feature of silicon reaction is very high affinity of silicon with oxygen, silicon can be used as a deoxidizing agent.

By equation 14

(17)

                                                                                           
   by equation 16 and using , we get

(18)

Equation 18 shows drastic reduction in oxygen content of steel due to addition of silicon. This suggests that silicon is a very effective deoxidizer. Normally silicon is used as ferrosilicon in steelmaking.

Reference

• A. Ghosh and A. Chatterjee; Ironmaking and steelmaking
• R. Tupkary et.al. Modern methods of steelmaking
• A.K.Chakrabarti: Steelmaking