High alumina slag ball and preparing method thereof

Abstract

The high-aluminum slag ball used as molten steel surface heat insulating and refining agent in smelting pure steel contains metal aluminum, alunina, titania, boron sesquioxide, calcium carbonate, fluorite powder and evitable impurity. With controlled silica, carbon, sulphur and phosphorus contents, the high-aluminum slag ball is suitable for use in smelting low-carbon and low-silicon pure steel or other super-pure steel. It has low water content to avoid molten steel sputtering and content of deoxygenating and alloying elements capable of being altered in wide range to suit for steel variety change. It has excellent performance of heat insulating for the surface of molten steel, and makes the deoxygenation and refining completed simultaneously to reduce included oxide in molten steel.

Description

technical field [0001] The invention belongs to the technology of external treatment, refining and alloying of molten steel, in particular to an additive for molten steel surface heat preservation and molten steel refining for alloying treatment, especially for smelting pure steel and ultra-pure steel, and in primary smelting After the steel is added, it can quickly cover the surface of the molten steel as an insulating agent. When it is transferred to the refining furnace with the molten steel, it has a strong deoxidation effect and can be synthesized into a refining agent with good performance. Background technique [0002] As we all know, with the development of the national economy, the requirements for steel types and their quality are increasing day by day, and the steel smelting technology has developed from the original one-step steelmaking to the two-step steelmaking, which is divided into two steps: primary smelting and refining. The temperature of molten steel and...

AI Technical Summary

Problems solved by technology

The second is that the molten steel comes out of the furnace without slag, and a carbonaceous thermal insulation agent (such as carbonized rice husk) with better thermal insulation performance is added to the surface of the molten steel to isolate and insulate the molten steel. extremely unfavorable

The third is to use a low-carbon protective agent based on coal fly ash. Although this protective agent avoids excessive carburization of molten steel, the main component of coal fly ash, Al 2 o 3 and SiO 2 On the one hand, during the refining period, the molten steel "returns to silicon" due to reduction, which is very unfavorable for smelting some low-carbon steel types (such as deep-drawing sheet steel); on the other hand, a large amount of Al 2 o 3 It takes a lot of CaO (lime powder) to form CaAl 2 o 4 (Calcium metaaluminate) becomes slag and floats up, otherwise it will reduce the Al in steel 2 o 3 Inclusion is also bad

In the prior art, on the one hand, a composite deoxidizer (such as Al-Si-Fe alloy, Al-Mn-Fe alloy) is used to form Al 2 o 3 , SiO 2 or MnO, Al 2 o 3 Low melting point eutectic, which is convenient for slag formation and flotation, but this method has limited application range, because it is difficult to form silicon or manganese oxides in the presence of a large amount of metal aluminum

Al-Ca-Fe alloys and Al-Ba-Fe alloys studied in the field of ferroalloys can replace Al-Si-Fe alloys and Al-Mn-Fe alloys to solve the problem of compound slagging of deoxidized products in smelting pure steel or ultra-pure steel, but there have been no successful reports so far.

Another aspect is the addition of calcium oxide to molten steel during refining to form CaO.Al 2 o 3 (Calcium metaaluminate) eutectic with low melting point forms slag and floats up, but this method is deoxidation first, and the compound slag of deoxidation products is behind, and the Al dispersed in the steel 2 o 3 It takes a long time to combine with CaO to form slag and float up to remove Al 2 o 3 The dynamic conditions are far from ideal

[0006] In order to make the molten steel pure, the molten steel must be deeply decontaminated, but the conditions for decontamination must be strong oxygen blowing to the molten steel, so that the impurities in the molten steel are oxidized into slag and float up, but at the same time, the oxygen content in the molten steel will increase, and the molten steel must be decontaminated. For deoxidation treatment, the deoxidation substances include aluminum, calcium, magnesium, silicon, manganese, etc. If calcium deoxidation is used, the cost will be too high. If magnesium deoxidation is used, there will be safety hazards, and the deoxidation effect of silicon, manganese and other substances will not meet expectations. Target, the original pure aluminum and aluminum-iron alloys can achieve the goal of deoxidation of pure steel, but cannot generate thermal insulation agent on the surface of molten steel, which is not conducive to the adsorption of deoxidation products and impurities