JP5900376B2 - Repair method of impeller for mechanical stirrer - Google Patents

Description

  The present invention relates to a method for repairing an impeller for a mechanical stirrer used by being immersed in molten iron in a hot metal desulfurization process, and in particular, mainly while leaving a reusable shaft refractory, The present invention relates to a method of repairing a refractory material of a severely damaged blade portion.

  The mechanical stirrer used for hot metal desulfurization treatment has an impeller that can be raised and lowered, and this impeller is immersed in molten iron, and in that state, the impeller is rotated by an electric motor or the like to stir the molten iron. This is a device for reacting a refining agent added to molten iron with molten iron. The impeller is composed of a shaft portion and a blade portion, and is manufactured by pouring an irregular refractory into the outer periphery of the shaft portion core and the blade portion core. The blade core metal is welded to the shaft core metal.

  In the hot metal desulfurization treatment, the impeller blades rotate while being immersed in the hot metal, and after the desulfurization treatment, the blades are pulled up from the hot metal and wait in the atmosphere until the next desulfurization treatment. That is, since the impeller is repeatedly subjected to heating by immersion in hot metal and cooling during standby, a large thermal shock is applied to the refractory of the impeller and a crack occurs in the refractory. In particular, the refractory is easily peeled off at the blade portion having a complicated shape, and when the core metal is exposed due to the refractory peeling, further use is impossible, and the impeller is replaced with another impeller. . After using the impeller, disassemble the refractory around the impeller, collect the core, repair the core, and then apply the refractory to the repaired core and reuse it. It is either reused or disposed of entirely, including the mandrel.

  Since the replacement of the impeller causes a decrease in productivity, means for extending the service life of the impeller has been proposed in order to reduce the replacement frequency of the impeller. For example, in Patent Document 1, the distance from the upper surface of the impeller blade portion to the uppermost position of the refractory applied to the shaft portion is 65% or less of the length from the upper surface of the blade portion to the upper end of the shaft portion, and There has been proposed an impeller that is positioned 200 mm or more higher than the hot metal interface during hot metal immersion. According to Patent Literature 1, cooling from the shaft cored bar is promoted, thereby suppressing an increase in the temperature of the blade cored bar and reducing the amount of erosion of the blade refractory.

  Patent Document 2 proposes an impeller having a double pipe structure in which a shaft cored bar uses air as a cooling gas over its entire length. According to Patent Document 2, the amount of wear of the blade refractory is reduced by cooling the blade core with the cooling air.

  Patent Document 3 proposes an impeller having a stud extending from a blade core metal to a lower outer edge portion of the blade refractory. According to Patent Document 3, the refractory is prevented from falling off at the lower outer edge of the blade portion, and the number of times the impeller can be used is increased.

JP 2004-35957 A JP 2010-116583 A JP 2011-184762 A

  However, the above prior art has the following problems.

  Although the service life of the impeller is extended by the means proposed in Patent Documents 1 to 3, Patent Documents 1 to 3 do not propose any repair method for the impeller after use. It is considered that the conventional processing method is performed. In other words, after disassembling the refractory around the impeller after use and recovering the core, repairing the core, and then applying the refractory to the repaired core, reusing only the core, This is a method of disposing of the entire impeller after use, including the cored bar.

  That is, in Patent Documents 1 to 3, since the number of times that the impeller can be used is extended, the replacement frequency is reduced. However, each time the impeller is replaced, a large amount of refractory waste or metal core waste is generated from the used impeller. become. This should be reviewed from the viewpoint of effective use of resources.

  The present invention has been made in view of such circumstances. The purpose of the present invention is to repair refractory debris and cores for the purpose of reusing a used impeller used in a mechanical stirring device. It is to provide a method for repairing an impeller without generating a large amount of gold dust, and further to provide a repair method that can increase the service life of an impeller after repair to a level comparable to a new impeller. It is.

The gist of the present invention for solving the above problems is as follows.
[1] A method for repairing an impeller composed of a shaft portion and a blade portion, the refractory material for the entire blade portion of the impeller after use, and a refractory material under the shaft portion connected to the refractory material of the blade portion Only after dismantling, and then pouring the amorphous refractory to cover the exposed shaft core and blade core and to form a refractory layer with a thickness equivalent to the refractory layer thickness before use. A method of repairing an impeller for a mechanical stirrer, characterized in that:
[2] A refractory layer having a thickness of 30 mm or more in a range of at least 50 mm from the boundary (joint) between the refractory material remaining in the shaft portion and the irregular refractory material poured into the shaft portion to be constructed. The method of repairing an impeller for a mechanical stirrer according to the above [1], wherein the irregular refractory is poured so as to cover the impeller.

  According to the present invention, since the shaft portion of the impeller for a mechanical stirrer is reused including the refractory, the amount of waste refractory generated from the impeller after use is reduced. It is possible to reduce the amount of the irregular refractory required to produce the impeller to 2745 kg, which is 3520 kg required, thereby effectively using resources and further reducing the cost of manufacturing the impeller.

It is a partial longitudinal cross-sectional schematic diagram of the new impeller before use. It is sectional drawing by the X-X 'arrow of FIG. It is a partial longitudinal cross-sectional schematic diagram of the impeller repaired by applying this invention. It is a partial longitudinal cross-sectional schematic diagram of the impeller of the other form which applied and repaired this invention.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a partial vertical cross-sectional schematic view of a new impeller before use at the time of manufacture, and FIG. 2 is a cross-sectional view taken along arrow X-X ′ in FIG. 1.

  As shown in FIGS. 1 and 2, an impeller 1 of a mechanical stirring device used for hot metal desulfurization treatment or the like includes a shaft portion 2 and a blade portion 3 connected to the lower portion of the shaft portion 2. Yes. The upper end of the shaft portion 2 is a flange 2a connected to a rotating shaft (not shown) driven by a power source such as an electric motor. The shaft portion 2 is configured by covering a shaft portion core metal 4 with a refractory layer 6. Similarly, the blade portion 3 includes a plurality of blade portion core metals 5 welded to the shaft portion core metal 4. A refractory layer 6 is coated around the periphery. A plurality of stirring blades 9 are formed so that each blade core metal 5 is covered with a refractory layer 6 so as to protrude from the shaft portion 2.

  In FIG. 1, only a part of the shaft portion 2 is covered with the refractory layer 6, but the entire shaft portion 2 may be covered with the refractory layer 6. Here, the refractory layer 6 is formed by casting an irregular refractory. The refractory layer 6 is stably formed, and at the same time, the shaft core 4 and the blade core of the refractory layer 6 are formed. In order to prevent peeling from the shaft 5, the shaft core 4 and the blade core 5 are provided with studs (not shown) as shown in Patent Document 3. In the case where the impeller 1 is newly manufactured, the refractory layer 6 is formed by pouring an indeterminate refractory into the shaft portion 2 and the blade portion 3 at the same time.

  In the mechanical stirring device, the impeller 1 can be moved up and down while being connected to a power source, and the blade portion 3 is immersed in molten iron such as hot metal, and the shaft portion 2 rotates via the power source in this state. Thus, the blade portion 3 formed integrally with the shaft portion 2 rotates around the shaft portion 2 as a rotation shaft, and thereby a plurality of stirring blades 9 provided so as to protrude with respect to the shaft portion 2. The molten iron is agitated. For example, a desulfurizing agent added to the molten iron by this stirring is stirred and mixed with the molten iron, and desulfurization and refining of the molten iron is performed. This refining is repeated.

  By repeatedly carrying out refining such as desulfurization refining on the molten iron, the refractory layer 6 of the blade portion 3 which is a part immersed in the molten iron is worn out. Further, since the heating by immersion in the hot metal and the cooling during standby are repeated, particularly, the refractory layer 6 of the blade 3 is subjected to a large thermal shock each time, and the refractory layer 6 is cracked. Or On the other hand, the heat load on the refractory layer 6 of the shaft portion 2 is small, and the amount of wear of the refractory layer 6 of the shaft portion 2 is extremely small compared to the blade portion 3.

  By using the impeller 1 repeatedly, when the remaining thickness of the refractory layer 6 of the blade portion 3 is less than the target value, or the refractory layer 6 of the blade portion 3 is peeled off and the blade portion core 5 If the impeller 1 is exposed, the impeller 1 cannot be used any more, so the impeller 1 is removed from the mechanical stirring device and replaced with another impeller, and the mechanical stirring device is used for refining molten iron. continue.

  The present invention is applied to the used impeller 1 after being removed.

  The used impeller 1 is removed from the mechanical stirring device, and the used impeller 1 is transported to the repair site. If the temperature of the impeller 1 is lowered to about room temperature, the target is a boundary line between the shaft part 2 and the blade part 3 or an arbitrary position between this boundary line and the position on the shaft part side about 100 mm from the boundary line. As a position, the refractory layer 6 on the blade portion side from the target position is disassembled, and the blade core metal 5 or the lower portion of the blade core metal 5 and the shaft core metal 4 is exposed. In this case, in order to prevent the impact force at the time of dismantling from being transmitted to the refractory layer 6 on the shaft side, a circumferential notch may be provided in the refractory layer 6 as a target position using a diamond cutter or the like. preferable.

  If the refractory layer 6 is disassembled, the shaft core 4 and the blade core 5 are repaired as necessary. In particular, the stud attached to the shaft core 4 and the blade core 5 may come off simultaneously with the refractory when the refractory layer 6 is disassembled, in which case a new stud is attached.

  Next, the refractory layer 6 is dismantled and poured into the unshaped refractory to form a new refractory layer. In FIG. 3, the partial longitudinal cross-section schematic of the impeller 1 after the repair which applied the present invention and constructed the refractory layer is shown. In FIG. 3, the hatched portion is the newly constructed refractory layer 7. Further, in FIG. 3, reference numeral 8 is a boundary between the refractory layer 6 to be reused and the refractory layer 7 applied at the time of repair, and this boundary 8 is also called “joint 8”. Other reference numerals in FIG. 3 are the same as those in FIG. The external dimensions of the refractory layer 7 are the same as the external dimensions of the refractory layer 6 of the new impeller 1 before use as shown in FIG.

  The joint 8 is only in contact with the refractory layer 6 and the refractory layer 7. When the impeller 1 after repair is immersed in molten iron such as hot metal, the molten iron travels through the joint 8. And the shaft core 4 and the blade core 5 may melt. In such a case, the service life of the impeller 1 after repair is limited.

  In order to prevent intrusion of molten iron from the joint 8, as shown in FIG. 3, the outer peripheral dimension of the refractory layer 6 to be reused and the outer peripheral dimension of the newly constructed refractory layer 7 are not the same. As shown in FIG. 4, it is preferable to cover the joint 8 with a refractory layer 7 which is newly poured and applied. FIG. 4 is a partial vertical cross-sectional schematic view of another form of impeller repaired by applying the present invention.

  That is, as shown in FIG. 4, it is preferable to cover the range of the distance L from the joint 8 to the shaft portion side with the refractory layer 7 having the thickness D. Here, the distance L is preferably 50 mm or more, and the thickness D is preferably 30 mm or more. If the distance L is less than 50 mm, molten iron may enter the joint 8 through the back surface of the refractory layer 7 covering the surface of the refractory layer 6. In addition, when the thickness D is less than 30 mm, the inflow of the irregular refractory is not sufficient during the casting of the irregular refractory, a defective filling portion is generated, and the refractory layer 7 covering the surface of the refractory layer 6 is formed. If the thickness D is less than 30 mm, the strength is insufficient, and cracks may be generated and peeled off.

  Thus, by covering the joint 8 with the refractory layer 7, the infiltration of the molten iron into the joint 8 is prevented, and the shaft core 4 and the blade core 5 are melted by the molten iron intrusion into the joint 8. Is prevented, and impeller replacement due to sudden occurrence due to melting of the shaft core 4 and the blade core 5 is avoided.

  The repaired impeller 1 is appropriately attached to a mechanical stirrer, and the molten iron is refined. In the present invention, as long as the refractory layer 6 of the shaft portion 2 is healthy, even the repaired impeller 1 is used. Repair again according to the above and use it again. That is, as long as the refractory layer 6 of the shaft portion 2 of the impeller 1 is healthy, the impeller 1 is repeatedly reused any number of times.

  As described above, according to the present invention, the shaft portion 2 of the impeller 1 for a mechanical stirrer is reused including a refractory material, so that effective use of resources and further reduction of impeller manufacturing costs are achieved. Is done. In addition, by repairing the joint 8 so as to be covered with the refractory material layer 7, it is possible to increase the service life of the impeller 1 after repair to an extent comparable to that of a new impeller.

  Hereinafter, an example to which the present invention is applied will be described.

  The impeller shown in FIG. 1 in which a shaft and blade refractories are newly constructed is attached to a mechanical stirrer, and using this mechanical stirrer, a hot metal desulfurization treatment of about 300 tons per charge is carried out, 300 When the charge desulfurization treatment was performed, that is, when the number of times of use reached 300, the impeller used was removed and replaced with another impeller. In this way, a plurality of used impellers were prepared.

  The amount of wear of the refractory layer on the shaft portion of the used impeller removed from the mechanical stirring device was measured. The shaft refractory layer before use had a diameter (designed diameter) of 650 mm, whereas the shaft refractory layer after use had a diameter of 638 mm to 640 mm, and the amount of wear was slight. In the repair, the shaft part was reused including the refractory.

  In order to set the position 30 mm from the boundary line between the shaft and the blade portion as a joint, a circumferential cut is provided at this position using a diamond cutter, and the refractory layer on the blade portion side than this cut Was demolished. After dismantling the refractory layer, a part of the stud was repaired, and then a refractory layer of the blade portion and a part of the shaft portion was newly formed by pouring construction of the irregular refractory.

  When a new refractory layer is formed, as shown in FIG. 3, the outer peripheral dimension of the refractory layer of the shaft portion to be reused is the same as the outer peripheral dimension of the newly constructed refractory layer (the present invention). As shown in FIG. 4, the construction of the refractory layer to be reused and the newly constructed refractory layer is covered with the newly constructed refractory layer (Example 2 of the present invention). ) And went. In Example 2 of the present invention, the distance L was 200 mm, and the thickness D was 75 mm.

  As a result, in the case of newly constructing the refractory of the shaft portion and the blade portion, 3520 kg of the unshaped refractory was necessary, but in Example 1 of the present invention, the impeller is manufactured with the 2745 kg of unshaped refractory. The amount of the amorphous refractory used can be reduced by 775 kg, and in Example 2 of the present invention, the amount of the amorphous refractory used can be reduced by 740 kg.

  In addition, as a result of using the repaired impeller for hot metal desulfurization treatment, in Example 2 of the present invention, no penetration of hot metal into the joint occurred, and 295 desulfurization treatments could be performed. In Invention Example 1, the number of times of use was 250 times, and it was confirmed that the service life of the impeller was improved by covering the joint.

1 Impeller 2 Shaft 2a Flange 3 Blade 4 Shaft Core 5 Blade Core 6 Refractory Layer 7 Refractory Layer 8 Joint 9 Stirring Blade

Claims (1)

A method for repairing an impeller composed of a shaft portion and a blade portion, and disassembles only the refractory material of the entire impeller blade portion after use and the refractory material under the shaft portion connected to the refractory material of the blade portion. and, thereafter, to form a refractory layer having a thickness corresponding to and prior to use refractory layer thickness covering the shank core metal and the blade portion core metal is exposed, have rows construction casting of monolithic refractories, A range of at least 50 mm on the shaft side from the boundary (joint) between the refractory remaining in the shaft and the irregular refractory poured into the shaft is covered with a refractory layer having a thickness of 30 mm or more. the features rows Ukoto the construction pouring of castable refractory, the repair method of the mechanical stirrer impellers.

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