2. Theoretical bases and essential functions of secondary metallurgy

During steel metallurgical treatment operations downstream of the main reactor, oxygen converter or arc furnace, various physico-chemical processes are implemented to remove certain dissolved or precipitated impurities:

• deoxidation and removal of most of the inclusions formed ;

• modification of the composition of residual or deliberately produced inclusions ;

• metal-milk transfer reactions: desulfurization, dephosphorization ;

• degassing: extraction of hydrogen, nitrogen and carbon monoxide.