The desulphurization and the control of sulphides by treatment of CaO-MgO-RE-CaF2 synthetic powder in liquid alloy is used with success in ladle for many alloy prod-ucts. The results indicated that the synthetic powder ladle treatment is possible to reduce sulphur from
0.035% to 0.009%S by employing agents amounting l4kg/t liquid metal.
The results also show that treated CaO-MgO-RE-CaF2 powder positively affect the globular type I morphology, small-smooth size and distribution of the remaining inclusions in the 12Cr20Ni38Mo5 alloy, The powder CaO- MgO-RE with increasing MgO shows better efficiency than powder with increasing CaO. Some calculated values have been compared with those reported in literature