The chemical composition of semi-steel after extracted-vanadium from hot metal with 4. 28% 〜5. 02% C and 0. 19% ~0. 24% V is 3. 30% - 3. 80% C and ≤0. 037% V. The “slag-remaining + double slag” process is remaining the slag of previous heat

charging extracted vanadium semi-steel and 50 ~ 70 kg/t scrap

adding lime and dolomite

blowing for 5 ~6 min

then tapping slag

adding suitable lime and dolomite and continuous blowing to end. Results show that in early blowing period

with increasing slag basicity or liquid temperature

the dephosphorization rate of liquid earlier increases and later decreases

and with increasing (FeO) in slag the dephosphorization rate of liquid earlier increases and later is constant

and the optimal control conditions are slag basicity 3.0 ~3.5

(FeO) 10.0% ~ 15.0% and liquid temperature at tapping slag 1480 ~ 1 510 ℃； in later blowing period

with increasing slag basicity the dephosphorization rate increases

while with increasing liquid temperature the dephosphorization rate decreases

the effect of (FeO) on dephosphorization is similar to that in the earlier blowing period

it is available to control the slag basicity 3. 5 ~ 4.0

(FeO) 8.0% ~ 10.0% and liquid temperature ≤1 630 °C at BOF blowing end and the dephosphorization rate is more than 90.0% ； and the liquid end [P] shall be controlled less than 0. 015% to meet the requirement for low phosphorus steel steelmaking.