Semi-steel making method

Abstract

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.

Description

technical field [0001] The invention relates to the technical field of iron and steel metallurgy, and more specifically relates to a method for producing low-phosphorus molten steel by using semi-steel after vanadium extraction. Background technique [0002] For enterprises using vanadium-titanium ore resources for smelting and production, in order to ensure the effective use of vanadium resources, it is necessary to extract vanadium and desulfurize before steelmaking. The molten steel obtained after vanadium-containing molten iron is desulfurized and vanadium-extracted is usually called semi-steel. In the semi-steel, the mass percent content of carbon is 3.4%-4.0%, the content of exothermic slagging elements such as silicon and manganese are trace amounts, and the mass percent content of sulfur in the semi-steel is controlled within 0.015%. However, due to no dephosphorization treatment, the mass percentage of phosphorus in the semi-steel is usually 0.060% to 0.080%, which...

AI Technical Summary

Problems solved by technology

However, this method also has the following disadvantages: adding a deep dephosphorization agent to the ladle in advance has strict requirements on the control of the oxygen content of the molten steel. If the oxygen content of the tapping is too high, the ladle may be "shot" during the tapping process or after the tapping is completed. Phenomena, there are certain safety hazards; deep dephosphorization agent must be added to the ladle before and after tapping and weak deoxidation treatment of molten steel, which makes the dephosphorization treatment time too long and slows down the production rhythm

However, this method has the following disadvantages: when the phosphorus content in the furnace is too high, it is difficult to control the final phosphorus within 0.006% by using the single slag method;

However, the patent application does not describe the length of time for the dephosphorization oxygen lance to be used in smelting, and there is no subsequent dephosphorization method after changing to a normal oxygen lance for smelting

Images