Pretreatment method of molten iron

Abstract

The present invention relates to a method for pretreatment of molten iron, which uses a single converter type refining furnace to continuously perform desiliconization and dephosphorization of molten iron with an intermediate slagging process, in which a sufficient amount of The slag is quickly discharged out of the furnace, and sufficient dephosphorization treatment can be performed in terms of cost and quality. The pretreatment method of the present invention includes: a desiliconization treatment process, supplying a gaseous oxygen source to the molten iron (5) in the converter type refining furnace (1) from a top blowing lance (2) to desiliconize the molten iron; a slagging process, At least a part of the slag generated in the desiliconization process is discharged from the converter type refining furnace; in the dephosphorization process, after the slagging process, a CaO-based flux is added to the converter type refining furnace, and a gaseous oxygen source is supplied from the top blowing lance , dephosphorize the remaining molten iron, wherein, in the desiliconization process, the slag height in the furnace is measured, and the measured slag height is defined by the distance from the molten iron bath surface in the furnace to the furnace mouth The desiliconization process is completed in a state where the height ratio of the melting chamber in the furnace is in a predetermined range.

Description

technical field [0001] The present invention relates to a pretreatment method of molten iron in which desiliconization and dephosphorization of molten iron are continuously performed using a converter type refining furnace, and an intermediate slagging process is interposed between the desiliconization and dephosphorization. Background technique [0002] In recent years, the development of pretreatment technology for molten iron using a converter-type refining furnace has progressed, and the following pretreatment methods have been developed. That is, a refining method has been developed in which, after desiliconization of molten iron in a converter-type refining furnace, the converter-type refining furnace is tilted and the slag in the furnace (the slag generated by the desiliconization process is referred to as "desiliconization slag") has been developed. ") at least part of it is discharged, and then CaO-based flux is thrown into the furnace to dephosphorize the remaining...

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Problems solved by technology

However, for desiliconization slag with low electrical conductivity, the reflectivity of microwaves is very small and most of them pass through, so there are also reflected waves from the molten iron bath surface and multiple reflected waves on the molten iron bath surface and the slag surface, so The method of Patent Document 4 cannot detect the slag level

[0013] In addition, in Patent Document 5, an antenna for transmission and reception is inserted into a furnace, and in a refining furnace exposed to high-temperature slag and molten iron droplets, these droplets adhere to and solidify on the On the antenna, it is difficult to measure continuously during the refining period

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