Steelmaking method of ladle refining furnace

Abstract

The invention discloses a steelmaking method of a ladle refining furnace. The method comprises the following steps of: (1) conveying primarily-refined molten steel of a converter into a ladle refining furnace, after a period of time for powering to heat and adding synthetic slag at a refining station, adding 0.25 to 0.5kg of multiple effect refining agents per ton of molten steel once only, wherein the multiple effect refining agent is prepared from the constituents having the following percentages by weight: 45-70% of CaC2, 5-20% of SiC, 5-15% of Al and 10-20% of sustained release agents; (2) performing slag modification according to the change of the slag and adding 0.05-0.20kg of slag per ton of molten steel each time; and (3) adding 4-15kg powdered slag of bauxite or CaSi per furnace 5-10 minutes before finishing refining in the ladle refining furnace. In the method, the elements of Ca, Al, Si and C in the constituents all have strong deoxidizing capacity, which meets the requirements of fast and deep deoxidization for slag and diffusive deoxidization to molten steel; the product of deoxidizing elements can form a white slag mineral phase with the synthetic slag, which is beneficial to desulfurization and inclusion removal of molten steel; and the content of N and H is reduced in the process of refining molten steel, thereby the consumption and the cost are reduced.

Description

technical field [0001] The present invention relates to a ladle refining furnace (ladle refining furnace) multi-effect refining agent (auxiliary slagging material) applied to refining slag reducing (or weakly oxidizing) atmosphere to produce molten steel refining foam white slag technology, is a kind of The invention discloses a steelmaking method for smelting high-quality steel grades at low cost, and belongs to the field of refining molten steel outside a furnace. Background technique [0002] Ladle refining furnace, namely LF furnace (LADLE FURNACE), is the main refining equipment outside the furnace in steel production. Its main tasks are: ①Desulfurization ②Temperature adjustment ③Precise composition fine-tuning ④Improve the purity of molten steel ⑤Slagging. As users' demand for high-grade steel, especially clean steel with low nitrogen, hydrogen, phosphorus, sulfur, oxygen and low inclusions, has greatly increased, such as X65 anti-H 2 S submarine pipeline steel, X52QS...

AI Technical Summary

Problems solved by technology

As users' demand for high-grade steel, especially clean steel with low nitrogen, hydrogen, phosphorus, sulfur, oxygen and low inclusions, has greatly increased, such as X65 anti-H 2 S submarine pipeline steel, X52QS anti-strong acid ultra-low sulfur pipeline steel, CS-110SS anti-corrosion oil casing steel, WB36CN1 nuclear power pipe steel, etc. These high-quality products have a high mass fraction of nitrogen and hydrogen in steel Requirements, conventional ladle refining furnace refining technology is difficult to achieve

For this reason, "calcium carbide + aluminum powder + ferrosilicon powder + fluorite", "synthetic slag + slag washing reducing agent", "synthetic slag + molten calcium aluminate + slag washing reducing agent" and other refining slags have been implemented at home and abroad. Although the above-mentioned nitrogen, hydrogen and inclusion control technologies can achieve certain metallurgical effects, they all have shortcomings, especially difficult to achieve the best metallurgical effect of the ladle refining furnace

[0003] The traditional "calcium carbide + aluminum powder + ferrosilicon powder + fluorite" auxiliary slagging process has the disadvantages of too fast foaming agent, short foam retention time, poor stability, high consumption, serious environmental pollution, labor problems such as high strength

[0004] There are two disadvantages in using the slag-washing reducing agent as the refining agent: first, because the main functional components of the slag-washing reducing agent are restricted by resources and are unstable, such as Al content fluctuates greatly, Al 2 o 3 , SiO 2 The content is generally high; therefore, it is difficult to match the deoxidation ability of the refining furnace slag with the white slag making process of the refining furnace

When the end point [C] of the molten steelmaking converter was low and the amount of slag was large, it was necessary to add a large amount of slag washing reducing agent for deoxidation, but then the slag (Al 2 o 3 ) (SiO 2 ) and other acidic oxides, the decrease of slag alkalinity and surface tension are not conducive to the formation, maintenance and stable foaming of white slag, and in severe cases, "glass slag" will be formed

Using this material to assist slagging makes it difficult to stably realize metallurgical functions such as deep desulfurization and removal of inclusions in molten steel

Second, because the foaming components of the slag washing reducing agent are very few, it is difficult for the refining slag to form long-term stable foaming and realize the submerged arc heating of the electrode, and the molten steel can easily absorb N and H; therefore, the slag washing reducing agent is used to assist slagging process, not conducive to the effective control of molten steel [N], [H] content

However, using carbonates (such as CaCO 3 , MgCO 3 etc.) have two disadvantages as blowing agent: the one, blowing agent foams too fast, foam stability is poor, and blowing agent consumes high, serious environmental pollution

Second, carbonates (such as CaCO 3 , MgCO 3 etc.) CO produced by decomposition at high temperature (decomposition temperature is about 800°C) 2 It is an oxidizing gas, which is harmful to the secondary oxidation of molten steel

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