Efficient circulation modification smelting method for RH furnace steel ladle top slag

Abstract

The invention discloses an efficient circulation modification smelting method for RH furnace steel ladle top slag. The modification smelting method includes the following steps that 1), after RH furnace circulation deep decarbonization is completed, aluminum particles/ferrotitanium is added for deoxygenation alloying, the vacuum degree of a vacuum tank is reduced to 20-30 kpa, and closed circulation is formed by molten steel in the vacuum tank and molten steel on the upper layer of a steel ladle; 2), 200-300 kg of modifier is weighed from an alloy material bin, and the modifier is added into the vacuum tank through an alloy vacuum hopper; 3), steel ladle bottom argon blowing is started, the pressure is adjusted to be 0.2-0.4 Mpa, the flow is 30-50 NL/min, and it is guaranteed that the steel ladle top slag slightly moves and the molten steel is not exposed; and 4), the modifier is added for circulation for 3-4 min, the steel ladle bottom argon blowing is stopped, the vacuum degree of the vacuum tank is controlled below 67 pa, the top slag is re-pressed after pure circulation is carried out for 8-10 min, and the top slag is delivered out of a station. The furnace slag total iron is controlled within 2%, the purity degree of the molten steel is increased, the continuous casting pouring continuous pulling charge number is 10, and the quality of casting blanks and rolled metal is obviously improved.

Description

technical field [0001] The invention belongs to the field of iron and steel metallurgy and steelmaking, and in particular relates to a high-efficiency circulation upgrading smelting method for RH furnace ladle top slag. Background technique [0002] With the simultaneous and rapid development of domestic metallurgical equipment and technology, special steel products have been more extensively developed and applied. RH vacuum furnace originated in Germany and developed in Japan. In recent years, it has been rapidly applied and developed in China, and the smelting products are increasing, including thick plate high strength, pipeline, ship plate, pressure vessel, and broadband cold-rolled ultra-low carbon deep-drawing steel and silicon steel. Wait. Among them, when smelting ultra-low carbon and other deep-drawing steels, the converter-RH furnace-slab continuous casting machine smelting process is adopted, and the LF refining furnace is not used for deoxidation and slagging op...

AI Technical Summary

Problems solved by technology

However, due to the excessive addition of the ladle top slag modifier in the early stage and excessive deoxidation, oxygen transfer and aluminum deoxidation reactions will occur at the steel slag interface, the reaction rate of oxygen and carbon in molten steel will slow down, and the decarburization effect and end point carbon tend to be too high , which has a great impact on the product's compositional stability and pass rate

[0005] Insufficient modification of ladle top slag: Converter-RH furnace-slab continuous casting machine smelting process is adopted. The modifier is usually added when the RH furnace is repressed and exits the station. Because the top slag is prone to crusting problems, it cannot Fully react with the slag surface, the modification effect is obviously insufficient

At the same time, the modification is carried out at this time, and the addition is late according to the process reasoning. Because the molten steel is completely deoxidized after alloying, but the total oxygen of the top slag is high, it will inevitably cause a direct reaction at the interface of the steel slag, which will affect the purity of the molten steel.

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