For the problem of nozzle blockage in the production of sulfur-containing steel (0. 10% ~ 0. 21% C

0. 010% ~0. 050%S) in a steel plant

a comprehensive analysis of the steel samples and nozzle plugging samples of each key process has been carried out by SEM and EDS. The results show that the inclusions with particle size less than 10 fim in each process steel are more than 94%

the number of inclusions per unit area decreases first and then increases with the process flow. The types of inclusions are mainly CaS

CaO-MgO

MnS

MgO-Al

2

O

3

Al

2

O

3

CaO~Al

2

O

3

CaO

CaO- MgO-Al

2

O

3

composite inclusions; the nozzle plug is mainly composed of FeO

Al

2

O

3

MgO • A1

2

O

3

CaO • Al

2

0

3

CaO • 2Al

2

O

3

. With blowing a certain amount of coke powder to the molten steel before EAF the tapping ； controlling the refined slag (FeO) ≤l.50%

basicity 2.0 ~4.0 and taking appropriate calcium treatment and staged argon blowing operation； to control the feeding speed of the sulphur wire in the range of 50 ~150 m/min； and cleaning the tundish and using special slag for sulfur-containing steel etc process measures

the nozzle blockage decreases

the sulfide rating is ≤3

the secondary oxidation of liquid reduces

and the casting accident is avoided.