JP5358987B2 - Impeller of mechanical stirring desulfurization equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an impeller for mechanical-stirring type desulfurizing apparatus with which in the case of applying the desulfurize-treatment to molten iron with the mechanical-stirring type desulfurizing apparatus provided with the impeller, a new facility reforming cost is not needed, and aggregation of a CaO-based desulfurizing agent can be restrained and thereby, the desulfurizing reaction interfacing area is increased and the desulfurize-treatment can efficiently be performed by making to be high of the desulfurizing reaction efficiency. <P>SOLUTION: The impeller 1 for mechanical-stirring type desulfurizing apparatus is provided with: an impeller shaft 2; a plurality of blades 3 arranged at the periphery of the impeller shaft, and applying the desulfurization to the molten iron by rotating with the impeller shaft as rotation-center; and a projecting part 4 inclined to the lower part toward the impeller shaft side from the blade side and projected to lower part in the impeller shaft side, is provided on the lower surface of the blades and the impeller shaft. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  TECHNICAL FIELD The present invention relates to an impeller that is installed at the lower end of a mechanical stirring desulfurization apparatus and rotates and stirs and mixes hot metal and a desulfurizing agent while immersed in hot metal.

  When manufacturing steel from hot metal melted in a blast furnace, the hot metal discharged from the blast furnace has a high concentration of about 0.04 to 0.05 mass% of sulfur (S) that adversely affects the quality of the steel. In addition, in the converter refining process of the next process, the purpose is to remove impurities by oxidation refining, so removal of sulfur mainly removed by reduction reaction cannot be expected. In the hot metal stage where it is easy to desulfurize due to the influence of the above, the hot metal is preliminarily desulfurized by various methods according to the required quality.

This preliminary desulfurization treatment may be carried out by blowing an inert gas such as Ar gas into the hot metal and stirring the hot metal to add the desulfurization agent into the hot metal with the carrier gas, or by impellers immersed in the hot metal (" The method is generally carried out by adding a desulfurization agent while stirring the hot metal by rotating the rotary blade or the “rotary blade”, and is particularly high even when an inexpensive CaO-based desulfurization agent is used. Since a desulfurization rate can be obtained, a desulfurization method using a mechanical stirring method has become the mainstream in recent years. In this case, as the CaO-based desulfurization agent, quick lime alone or a mixture obtained by adding fluorite (CaF ₂ ) or alumina (Al ₂ O ₃ ) to quick lime is used. The desulfurization reaction by the CaO-based desulfurization agent proceeds based on the reaction formula shown by “CaO + S → CaS + O”. Incidentally, a desulfurization apparatus using a mechanical stirring method is called a mechanical stirring desulfurization apparatus.

  FIG. 2 shows a hot metal desulfurization treatment method in a mechanical stirring desulfurization apparatus equipped with a conventional impeller. In this desulfurization treatment method, as shown in FIG. 2, the impeller 1 having a plurality of blades 3 immersed in the hot metal 8 is rotated about the impeller shaft 2 as a rotation axis, thereby turning and stirring the hot metal 8. In this state, the CaO-based desulfurizing agent 9 is added to the hot metal via the chute 7 to disperse the CaO-based desulfurizing agent 9 in the hot and swirling hot metal, and the sulfur in the hot metal and the CaO-based desulfurizing agent 9 Is a method of desulfurization by reacting. In FIG. 2, reference numeral 5 denotes a processing container, and 6 denotes a transport carriage.

  However, in the desulfurization process using the mechanical stirring type desulfurization apparatus, the desulfurization agent cannot be pulverized in order to prevent the CaO-based desulfurization agent from being sucked into the dust collector or scattered to the surroundings. Used in the form of particles of about 2 mm. The melting point of CaO is a high temperature exceeding 2000 ° C., and the reaction with sulfur in the hot metal occurs only on the surface of the CaO-based desulfurization agent, and the inside of the CaO-based desulfurization agent does not contribute to the desulfurization reaction. In addition, the CaO-based desulfurization agent has poor wettability with hot metal, and is difficult to get caught in the hot metal, and the desulfurization agent added to the hot metal bath is agglomerated in the bath surface of the hot metal or in the bath with strong stirring. As a result, the reaction interface area further decreases.

  For this reason, the desulfurization reaction efficiency of the CaO-based desulfurization agent is currently as low as about 6%. Here, the desulfurization reaction efficiency is the ratio of the mass of CaO that contributed to the desulfurization reaction to the mass of added CaO, and therefore, 90% or more of CaO in the CaO-based desulfurization agent does not contribute to the desulfurization reaction. ing.

  Therefore, many techniques for increasing the desulfurization reaction efficiency of CaO-based desulfurization agents have been proposed.

  For example, Patent Document 1 proposes an impeller provided with a blowing hole for blowing a powder desulfurizing agent in a substantially horizontal direction on the side wall of the impeller shaft. According to Patent Document 1, by blowing in a substantially horizontal direction, the CaO-based desulfurizing agent trapped in the gas reservoir formed below the impeller is greatly reduced, and aggregation of the CaO-based desulfurizing agent is suppressed. It is said that it is efficiently dispersed in the hot metal. Patent Document 2 discloses an iron-coated desulfurization wire in which a hot metal being stirred by an impeller is coated with a CaO-based desulfurization agent with a steel sheath material when the hot metal is desulfurized using a mechanical stirring desulfurization apparatus. A method of supplying and desulfurizing has been proposed. According to Patent Document 2, even when an ultrafine CaO-based desulfurization agent is added, there is no scattering at the time of addition, the addition yield of the desulfurization agent is improved, and the added desulfurization agent is vigorously stirred with hot metal, The desulfurization reaction interfacial area is increased to promote the desulfurization reaction, and the desulfurization reaction efficiency can be improved.

  However, in Patent Document 1, it is necessary to install a blow hole in the impeller, and in Patent Document 2, an apparatus for supplying an iron-coated desulfurization wire is required, both of which are conventional mechanical stirring desulfurization. There is a disadvantage that a new device must be added to the device, that is, a new facility modification cost is required.

By the way, Patent Document 3 proposes an impeller in which a slag adhesion preventing plate having an inclination of 30 to 70 degrees is provided on the upper surface of the impeller, or an inclination of 30 to 70 is provided on the upper surface of the impeller itself. However, Patent Document 3 is a technique for preventing the desulfurization agent from adhering to and depositing on the top of the impeller during the desulfurization process, and is a technique different from the technique for improving the desulfurization reaction efficiency.
JP 2006-28615 A JP 2007-31810 A JP 2001-248976 A

  The present invention has been made in view of the above circumstances, and the object of the present invention is to eliminate CaO-based desulfurization without spending new facility modification costs when desulfurizing hot metal with a mechanical stirring desulfurization apparatus equipped with an impeller. It is an object of the present invention to provide an impeller for a mechanically agitated desulfurization apparatus that can suppress agglomeration of the agent, thereby increasing the desulfurization reaction interfacial area and increasing the desulfurization reaction efficiency to efficiently perform the desulfurization treatment.

  The inventors of the present invention diligently studied and studied to solve the above problems. As a result, the place where the CaO-based desulfurizing agent is most likely to aggregate is a portion where the flow rate of the hot metal formed immediately below the impeller is reduced, and an impeller having a shape such that this portion is not formed or reduced is used. Thus, it was found that aggregation of the CaO-based desulfurizing agent was suppressed and the desulfurization reaction efficiency was improved.

  The present invention has been made based on the above knowledge, and the impeller of the mechanical stirring desulfurization apparatus according to the present invention includes an impeller shaft and a plurality of blades provided around the impeller shaft, and the impeller An impeller of a mechanical stirring type desulfurization device that rotates about a shaft as a rotation center and desulfurizes hot metal, and is inclined downward from the blade side toward the impeller shaft side on the lower surface of the blade and the impeller shaft. The protrusion part which the side protruded more below is provided.

  According to the impeller of the mechanical agitation desulfurization apparatus according to the present invention, the lower surface of the impeller is provided with a protrusion that protrudes further downward on the impeller shaft side. When a conventional impeller having a flat bottom is used, a portion where the hot metal flow velocity decreases immediately below the formed impeller is not formed, thereby suppressing aggregation of the CaO-based desulfurization agent and increasing the desulfurization reaction interfacial area. In addition, the desulfurization reaction efficiency is improved and the desulfurization treatment can be performed efficiently.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing a state in which hot metal is desulfurized using an impeller of a mechanical stirring desulfurization apparatus according to the present invention.

  As shown in FIG. 1, an impeller 1 of a mechanical stirring desulfurization apparatus according to the present invention includes an impeller shaft 2 and a plurality of blades 3 provided around the impeller shaft 2, and the blade 3 and the impeller shaft 2 are provided. A protrusion 4 is formed on the lower surface of the blade 4 so as to incline downward from the blade 3 side toward the impeller shaft 2 side, and the impeller shaft 2 side protrudes further downward. The protruding portion 4 is made of a refractory material like the blade 3, and may be constructed integrally with the blade 3 when the blade 3 is installed on the impeller 1, or after the blade 3 is installed, the protruding portion 4. Either may be formed. The impeller shaft 2 has a metal shaft center, and the outer periphery and the bottom thereof are covered with a refractory.

  Since the shearing force due to the hot metal 8 acts on the projecting portion 4 due to the impeller 1 rotating in the hot metal, the thickness of the joint portion of the projecting portion 4 with the blade 3 is equal to the thickness of the blade 3. It is preferable to do. Moreover, the protrusion height (H) of the protrusion part 4 does not need to prescribe | regulate in particular, The height which can give stirring power to the hot metal 8 is enough. Specifically, it is sufficient to ensure 100 mm as the protrusion height (H). Moreover, although the protrusion part 4 is installed in the lower surface of all the wing | blades 3 in FIG. 1, since the role of the protrusion part 4 adds stirring force to the hot metal 8, it exists in the lower surface of all the wing | blades 3. It is not necessary to install, and it is sufficient if it is installed on the lower surface of at least one blade 3.

  The mechanical agitation desulfurization apparatus includes a lifting device for immersing the impeller 1 in the hot metal 8 accommodated in the processing vessel 5, a driving device for rotating the impeller 1 around the impeller shaft 2, the impeller 1 and the above-mentioned A fixed frame for guiding the raising and lowering of the driving device, a dust collector for sucking and removing generated dust, and the like are provided, but are omitted in FIG.

  A method for desulfurizing the hot metal 8 using the impeller 1 according to the present invention having such a shape will be described below.

  First, the hot metal 8 discharged from the blast furnace is received in the processing container 5, or the hot metal 8 received in the torpedo car is transferred from the torpedo car to the processing container 5, and this processing container 5 is mounted on the transport cart 6. It is conveyed directly under the mechanical stirring type desulfurization apparatus 1. At this time, the impeller 1 is held in a state of being retracted above the processing container 5. The processing vessel 5 is preferably circular in horizontal cross section because the swirling and stirring of the hot metal 8 by the impeller 1 is easy to obtain. Therefore, as the processing vessel 5, the ladle type hot metal ladle or converter equipment is preferable. A ladle is suitable.

Next, the impeller 1 is lowered and immersed in the hot metal 8 accommodated in the processing container 5, and the descent is stopped when the impeller 1 reaches a predetermined immersion depth. At this time, the impeller 1 may be rotated in advance or may be rotated after being immersed. Thereafter, a CaO-based desulfurizing agent 9 is added over the hot metal 8 being swirled and stirred through the chute 7, and the desulfurization treatment is performed by appropriately adjusting the rotational speed of the impeller 1. As the CaO-based desulfurization agent 9, quick lime alone or limestone added with fluorite (CaF ₂ ) or alumina (Al ₂ O ₃ ) is used, and its size is maximized in order to increase the efficiency of the desulfurization reaction. The diameter of the particles is about 2 mm or less.

  Since the protrusion 4 is formed on the lower surface of the impeller 1, the hot metal 8 is vigorously stirred by the protrusion 4 even on the bottom surface of the impeller 1, and as a result, the hot metal flow rate immediately below the impeller 1 is sufficiently secured. The aggregation of the CaO-based desulfurizing agent 9 at the position is suppressed, the desulfurization reaction interfacial area is increased, and the desulfurization reaction proceeds efficiently.

  When the desulfurization process is performed for a predetermined time, the rotation of the impeller 1 is stopped, and the impeller 1 is lifted upward to complete the desulfurization process. After the desulfurization treatment, when further carrying out hot metal pretreatment such as converter equipment in the next step or dephosphorization treatment, the processing vessel 5 containing the hot metal 8 is carried out to the hot metal pretreatment equipment.

  As described above, by performing the desulfurization process using the impeller 1 according to the present invention, a portion where the molten iron flow velocity immediately below the impeller formed when the conventional impeller having a flat bottom is used is formed. Accordingly, the aggregation of the CaO-based desulfurizing agent 9 is suppressed, the desulfurization reaction efficiency is improved, and the desulfurization treatment can be performed efficiently.

It is a schematic sectional drawing which shows the hot metal desulfurization processing method using the impeller which concerns on this invention. It is a schematic sectional drawing which shows the hot metal desulfurization processing method using the conventional impeller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Impeller 2 Impeller axis | shaft 3 Blade | blade 4 Protrusion part 5 Processing container 6 Conveying cart 7 Chute 8 Hot metal 9 CaO type | system | group desulfurization agent

Claims (1)

An impeller for a mechanical agitation desulfurization apparatus comprising an impeller shaft and a plurality of blades provided around the impeller shaft, wherein the impeller shaft rotates around the impeller shaft to desulfurize the hot metal. the lower surface of the impeller shaft, and equal to the thickness of the blade thickness of the contact portion of the blade, inclined downward toward the blade side impeller shaft side, the impeller shaft side is more protruded downward, the protrusion height than 100mm An impeller for a mechanical stirring type desulfurization apparatus, wherein a protrusion for applying a stirring force to the hot metal is provided.

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