The invention provides a semi-steel making method. The method comprises the following steps of: a, adding a
slag forming material into a
molten pool of a converter, performing blowing
slag formation by a 5-hole
oxygen lance
oxygen-blowing process at the top of the converter and an
inert gas bottom blowing process at the bottom of the converter to remove
phosphorus in the
molten steel, and discharging
slag when the
molten pool temperature in the converter is 1,410 to 1,460 DEG C, the
alkalinity of the slag is 2.0 to 2.5 and the full
iron content of the slag is 10 to 15 weight percent; and b, adding the slag forming material into the
molten pool of the converter again, performing blowing slag formation again by a 6-hole Raoult
oxygen lance oxygen-blowing process at the top of the converter and the
inert gas bottom blowing process at the bottom of the converter to further remove the
phosphorus in the
molten steel, blocking slag and discharging steel when the molten
pool temperature in the converter is 1,670 to 1,700 DEG C, the
alkalinity of the slag is 3 to 4.5 and the full
iron content of the slag is 17 to 20 weight percent, and thus obtaining
molten steel, the
phosphorus element content of which is not more than 0.006 weight percent. The method has the advantages of good slag formation effect, short slag formation time,
high phosphorus removal efficiency and capabilities of remarkably reducing the full
iron content of the final point slag and keeping the phosphorus content of the steel less than 0.006 percent.