JP2007270170A - Sinter cake-supporting stand - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prolong the service life of a sinter cake-supporting stand disposed on a sintering pallet of a sintering machine. <P>SOLUTION: The following sections of a stand main body part 2, to be in contact with raw materials for sintering, are composed of a composite layer 4 prepared by dispersing alumina particles of 3 to 7 mm particle size in a matrix of heat resistant cast steel: a top surface; anteroposterior inclined surfaces; the upper part of both lateral surfaces; and the flange part along the above inclined surfaces. By this method, progress of wear in these sections can be retarded, and replacement cycle can be extended. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a sinter cake support stand of a sintering machine for producing sintered ore used as a raw material in a blast furnace or the like.

  In iron making processes such as blast furnaces, sintered ore obtained by sintering powder iron ore into a lump with a sintering machine is often used as a raw material. FIG. 4 shows a sinter production process by a general sintering machine. In this sintered ore production process, firstly, the main raw material powdered iron ore, the auxiliary raw material limestone, and the fuel coke are cut out from the hoppers 11, 12, and 13, respectively, and the returned ore cut out from the return hopper 14 together with the mixer 15. Condition and granulate to make a sintered raw material. The sintered raw material is transported to the surge hopper 16 and temporarily stored, then cut out from the drum feeder 17 and supplied to the supply portion of the sintered pallet 19 via the chute 18 so that the sintered raw material is placed on the sintered pallet 19. Layer 20 is formed. Then, the coke on the surface layer of the sintering raw material layer 20 conveyed by the sintering pallet 19 is ignited by an ignition furnace 21, and the coke is burned while sucking air below the sintering raw material layer 20. The sintering raw material layer 20 is sequentially sintered from the upper layer to the lower layer. The raw material thus sintered is discharged from the discharge part of the sintering pallet 19 as sintered ore.

  In the above sintering method, the upper layer portion of the sintering raw material layer is sintered before the lower layer portion to form a sintered mass (hereinafter referred to as “sinter cake”). The lower part of the raw material layer is compressed under the weight of the sinter cake and becomes dense. When the sintered raw material layer is densified, the air permeability is lowered, resulting in a reduction in the combustion rate of coke and uneven combustion. As a result, the sintering speed is slowed, the quality of the sintered ore discharged from the sintering pallet is highly varied, and the productivity tends to be lowered.

Therefore, by installing a support member that receives the weight of the sinter cake (hereinafter referred to as “sinter cake support stand” or simply “stand”) on the sintering pallet so as to be buried in the sintering raw material layer, It has been proposed to prevent a decrease in air permeability due to densification of the lower layer portion of the raw material layer and to improve the productivity of the sintered ore (see, for example, Patent Documents 1 and 2). This sinter cake support stand has a large temperature difference in the height direction on the way from the supply part of the sintering pallet to the discharge part, and when it returns from the discharge part of the sintering pallet to the supply part, the whole is cooled, Since they are repeatedly subjected to thermal stress, they are generally formed of heat-resistant cast steel having excellent heat fatigue resistance and sufficient high-temperature strength.
JP-A-2-293586 JP-A-4-168234

  However, the sinter cake support stand rubs against the raw material when the sintering raw material is supplied to the supply part of the sintering pallet or when the raw material after sintering is discharged as the sintered ore at the pallet discharging part. Therefore, the weight of the sinter cake cannot be supported gradually due to the thinning, and the air permeability of the sintered raw material layer cannot be prevented from being lowered. For this reason, relatively frequent stand replacement is required in the sintered ore manufacturing process, and the cost of manufacturing a new stand and the trouble of replacing the stand are factors that increase the maintenance cost of the entire sintering machine. In addition, there is also a problem that the rest period of the sintering machine becomes longer due to the stand replacement work.

  An object of the present invention is to extend the life of a sinter cake support stand installed on a sintering pallet of a sintering machine.

  In order to solve the above problems, the present invention is installed so as to be buried in a sintering raw material layer formed on a sintering pallet of a sintering machine, and by sintering the upper layer portion of the sintering raw material layer. In the sinter cake support stand that supports the produced sinter cake, at least a part of the portion that contacts the sintering raw material is formed of a composite layer in which hard particles are dispersed in a base material of heat-resistant cast steel. In this way, it is possible to delay the progress of wear at the contact portion of the sinter cake support stand with the sintered raw material and extend the replacement cycle.

As the material for the hard particles, any one of oxide, carbide, and nitride may be employed. Specifically, it is desirable to employ any one of alumina (Al ₂ O ₃ ), magnesia (MgO), zirconia (Zr ₂ O), silicon carbide, and silicon nitride. This is because each of these materials hardly reacts with the raw material, and has an appropriate hardness (Vickers hardness: HV 800 to 4000, preferably HV 900 to 4000). The hardness of each material is about HV2000 for alumina, about HV975 for magnesia, about HV1300 for zirconia, about HV2500 for silicon carbide, and about HV3300 for silicon nitride.

  The hard particles preferably have a particle size of 3 to 7 mm. When compounding hard particles when casting heat-resistant cast steel, if hard particles with a particle size of less than 3 mm are used, the melt of the heat-resistant cast steel is difficult to enter between the particles and the composite layer tends to be thin, whereas the particle size exceeding 7 mm When the hard particles are used, the area of the base material between the particles is increased, so that the base material between the particles is easily rubbed with the sintered raw material, and the effect of improving the wear resistance is reduced. At this time, the mixing ratio of the hard particles in the composite layer is such that the volume ratio of the hard particles to the base material is within the range of 10:90 to 90:10, and the thickness of the composite layer is preferably 3 to 10 mm.

  In the present invention, as described above, the contact portion with the sintering raw material of the sinter cake support stand is formed by the composite layer in which hard particles are dispersed in the base material of the heat-resistant cast steel. It is possible to extend the life of the stand by slowing down. Therefore, the sintering machine using this stand has a longer stand replacement cycle than before, and the maintenance cost can be reduced by reducing the production cost of the new stand and the labor cost of the stand replacement work. In addition, the suspension period for the stand replacement work can be shortened.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. As shown in FIGS. 1A to 1C, the sinter cake support stand 1 includes a trapezoidal plate-like main body portion 2 and a mounting portion 3 continuing below the main body portion 2. As shown in FIG. Two to four rows are arranged on a sintering pallet 19 of a sintering machine in a typical sinter manufacturing process (see FIG. 4) (FIG. 2 shows an example of a two-row arrangement). The height of the main body 2 is 300 mm, and the main body 2 is formed on the sintering pallet 19 and buried in the sintering raw material layer 20 having a height of about 600 mm. It is designed to support the sinter cake produced by ligation.

  The main body portion 2 and the mounting portion 3 are integrally cast of heat-resistant cast steel, and as shown in FIG. 1, the upper surface, the front and rear inclined surfaces, and both side surfaces of the main body portion 2 surface in contact with the sintering raw material The upper part and the edge part along the inclined surface are formed of a composite layer 4 in which hard particles are dispersed in a base material. The composite layer 4 has a thickness T of 3 to 10 mm, and as the hard particles, alumina having a particle size of 3 to 7 mm is used. The material is magnesia, zirconia, silicon carbide, silicon nitride. Such oxides, carbides, and nitrides may be used.

  Next, the manufacturing method of this stand is demonstrated. First, create a foam model with a shape that is the volume of the composite layer cut from a predetermined part of the product stand, and attach double-sided tape to the part where hard particles are to be composited. After tightly sticking, mask the alumina particles with another tape. Next, after applying a coating agent to the foamed model, the model is set on a casting frame and filled with sand to form a mold. Then, when the molten metal of heat-resistant cast steel is injected into the casting frame, the foam model and the tape are vaporized by the heat of the molten metal, and the molten metal is filled in the mold and enters between the alumina particles adhered to the model surface. A product in which alumina particles are combined at a predetermined site is obtained.

  Here, by aligning the particle size of the alumina particles to 3 to 7 mm, the molten metal easily enters between the particles during pouring, and the increase in the base material area between the particles is suppressed as much as possible. It can be formed with a sufficient thickness, and the friction between the base material and the sintered raw material between the particles can be suppressed, and a sufficient wear resistance improving effect can be obtained.

  In the above stand manufacturing method, the alumina particles are attached to the surface of the foamed model with a double-sided tape. However, alumina formed into a cylindrical shape may be pushed into a predetermined part of the model. At this time, if the end portion of the alumina is exposed from the model surface, the arrangement of the alumina is less likely to be disturbed during pouring, and the alumina can be more uniformly dispersed in a predetermined portion of the product.

  This sinter cake support stand has the above-described structure, and a portion of the contact surface with the sintering raw material where the wear progresses quickly due to rubbing with the sintering raw material is made of hard alumina particles on the base material of the heat-resistant cast steel. Since the composite layer 4 is dispersed, the progress of wear at this portion is slower than in the prior art and has a long life.

  3A to 3C show modified examples of the shape of the main body. In this modification, the upper surface of the main body 2 is formed as an upwardly convex arcuate surface, and the height is 100 mm higher than that of the example of FIG. 1, but the upper surface, the front and rear inclined surfaces, and the upper portions of both side surfaces The edge along the inclined surface is formed of the composite layer 4 in which alumina particles are dispersed in the base material, and the thickness T is 3 to 10 mm, which is the same as the example of FIG.

a is a front view of the stand of the embodiment, b is a side view of a, c is a cross-sectional view taken along line II of a a is a perspective view which shows the installation state of the stand of FIG. a is a front view of a modification of the shape of the main body, b is a side view of a, and c is a sectional view taken along line III-III of a Illustration of general sinter manufacturing process

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Stand 2 Main-body part 3 Attachment part 4 Composite layer 11, 12, 13, 14 Hopper 15 Mixer 16 Surge hopper 17 Drum feeder 18 Chute 19 Sintering pallet 20 Sintering raw material layer 21 Ignition furnace

Claims (4)

  In a sinter cake support stand that is installed so as to be buried in a sintering raw material layer formed on a sintering pallet of a sintering machine and supports a sinter cake generated by sintering the upper layer portion of the sintering raw material layer, A sinter cake support stand, characterized in that at least a part of a portion in contact with the sintering raw material is formed of a composite layer in which hard particles are dispersed in a base material of heat-resistant cast steel.   The sinter cake support stand according to claim 1, wherein the material of the hard particles is any one of oxide, carbide, and nitride.   The sinter cake support stand according to claim 2, wherein the material of the hard particles is any one of alumina, magnesia, zirconia, silicon carbide, and silicon nitride.   The sinter cake support stand according to any one of claims 1 to 3, wherein the hard particles have a particle size of 3 to 7 mm.

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