Fluxing agent for smelting steel as well as preparation and use methods thereof

Abstract

The invention discloses a fluxing agent for smelting steel as well as preparation and use methods thereof. The fluxing agent comprises the following components by weight percent: 70%-90% of 4CaO 7Fe2O3, 5%-20% of CaO Fe2O3, 1%-5% of SiO2, 0-3% of Al2O3, 0-3% of MgO and 0-5% of impurities. The preparation method comprises the following steps: evenly mixing an iron-containing waste material and a CaO-containing lime material in a ratio of ferric oxide to calcium oxide of 55%-75% to 25%-45%; pressing to form a sphere-shaped mixture with a diameter of phi 30-60mm; putting the sphere-shaped mixture in a cupola furnace for smelting, wherein the smelting temperature is controlled to 1200-1300 DEG C; in the smelting process, discharging a premelting material once per 8-12 minutes, and crushing the cooled premelting material in to blocks with a diameter of 40 mm below. The fluxing agent is used in a converter and a finery, and the addition amount of the fluxing agent is 0.3%-0.5% of loading amount of metals; and the fluxing agent is added once along with the first batch of slagging materials or is added along with the slagging materials in batch. The fluxing agent has the advantages of low melting point and good continuous slagging effect, can be used for alleviating corrosion on furnace lining and improving quality of molten steel, is beneficial to environment conservation, and the like.

Description

technical field [0001] The invention belongs to the technical field of steelmaking, in particular to a flux for steelmaking, that is, the mineral composition is 4CaO·7Fe 2 o 3 Main flux for steelmaking and its preparation method and use method. Background technique [0002] In the process of converter steelmaking, in order to ensure the early slag generation and smooth operation of dephosphorization, desulfurization and blowing, it is necessary to add a certain amount of flux. At present, the fluxes used in production mainly include the following types: [0003] 1. With CaF 2 Main composition: fluorite is a commonly used slagging agent, the main component of fluorite is CaF 2 , which has a low melting point and can significantly reduce the melting point of CaO, but because fluorite releases harmful (F -1 ) elements, causing environmental pollution, therefore, the use of fluorite as a flux has been banned. [0004] 2. Take Al 2 o 3 Main composition: vanadium class (bau...

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Problems solved by technology

[0003] 1. With CaF 2 Main composition: fluorite is a commonly used slagging agent, the main component of fluorite is CaF 2 , which has a low melting point and can significantly reduce the melting point of CaO, but because fluorite releases harmful (F -1 ) elements, causing environmental pollution, therefore, the use of fluorite as a flux has been banned

[0004] 2. Take Al 2 o 3 Main composition: vanadium class (bauxite, bauxite and bauxite as main raw material) flux, Chinese patent (patent No. 99113322.6) discloses a kind of flux with Al 2 o 3 It is mainly composed of bauxite flux, and its composition is: Al 2 o 3 ≥45%, SiO 2 ≤30%, Fe 2 o 3 : 7% ~ 8%, the balance is CaO, MgO, TiO 2 , P, S and other impurities, the particle size is 5-30mm, and the dosage is 1.6-9kg / ton steel. The effect of vanadium flux is relatively stable, but Al 2 o 3 Form 3CaO·Al with CaO in lime 2 o 3 and 12CaO·7Al 2 o 3 , the higher melting points are 1535°C and 1455°C respectively. Although the vanadium-based flux can play a role in melting slag, the effect of melting slag is not ideal due to the high melting point.

But its main composition is FeO and Fe 2 o 3 The reaction with CaO in lime needs to absorb part of the heat, so that the temperature drop of the molten pool is large; at the same time, FeO and Fe 2 o 3 The penetration ability is the strongest, and it can quickly destroy 2CaO·SiO 2 Shell, the speed of slag removal is fast, but the action time is short, the effect of continuous slag removal is not good, and the corrosion of the furnace lining is serious, etc.

[0006] The above-mentioned fluxes have problems such as polluting the environment; high melting point, unsatisfactory slag removal effect; large temperature drop of molten steel, short action time, and poor continuous slag removal effect.

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