Smelting method of steel for raw material pure iron

Abstract

The invention relates to a smelting method of steel for raw material pure iron, comprising the following steps of: I, tapping by a converter: tapping when P is less than or equal to 0.006%, S is less than or equal to 0.07% and C is 0.02-0.04% in liquid steel; and binary alkalinity of furnace slag is 3-4; II, primarily dephosphorizing: in the process of tapping by the converter, adding a liquid steel dephosphorizing agent into a steel ladle and powerfully agitating by argon; III, deeply dephosphorizing: adding lime after an LF (Low Frequency) furnace arrives, wherein the binary alkalinity of the furnace slag is 4-5; powerfully agitating by the argon and slagging off; adding the lime by the LF furnace and adjusting the slag by fluorite, wherein the alkalinity is 7-8; raising the temperature and adding aluminum powder to adjust the slag and powerfully agitating by the argon; IV, decarbonizing: conveying the steel ladle to an RH and arriving at the station and vacuumizing oxygen, wherein the vacuum degree is less than or equal to 4 mbar; and decarbonizing at the vacuum degree for 10-15 minutes; and V, desulfurizing: after decarbonizing, making the oxygen content after decarbonizing; adding aluminum according to a constant oxygen amount and adjusting; and adding a desulfurization agent, wherein the mass percentages of components in the liquid steel are as follows: the C is less than or equal to 0.002%, the S is less than or equal to 0.005%, the P is less than or equal to 0.002% and Al is less than or equal to 0.03%; and the others are Fe and unavoidable impurities. The smelting method of the steel for the raw material pure iron improves the purity of the liquid steel.

Description

technical field [0001] The invention relates to a method for smelting raw material pure iron steel. Background technique [0002] Ultra-low phosphorus, ultra-low sulfur and high-purity raw material pure iron is the basic material for the production of NdFeB magnetic materials, electrothermal alloys, precision alloys, low-carbon stainless steel, powder metallurgy, amorphous alloys and other special metal materials. [0003] Patent No. 02115419.8 discloses "a method for controlling phosphorus in the production of ultra-low phosphorus steel", which mainly produces killed steel, but does not elaborate on the dephosphorization of boiling steel. Due to the extremely low carbon content of high-purity raw material pure iron, undeoxidized tapping is used in the converter, and the thermodynamic conditions for dephosphorization and desulfurization are different. The smelting method of the existing raw material pure iron steel adopts the process route of primary smelting furnace (conve...

AI Technical Summary

Problems solved by technology

The smelting method of the existing raw material pure iron steel adopts the process route of primary smelting furnace (converter or electric arc furnace) + vacuum furnace, and desulfurization and dephosphorization are mainly carried out in the primary smelting furnace. After tapping, the molten steel temperature is too high or the ladle Excessive thickness of the inner top slag, resulting in severe phosphorus and sulfur reversion, and poor control of phosphorus and sulfur in molten steel