JP2007277594A - Sintered ore production method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sintered ore production method where a yield is improved by preventing powdering upon crushing when sintered ore is produced. <P>SOLUTION: A sintered ore production method characterized in that the charging raw material of coarse grains with a grain diameter of 10 to 20 mm selected from blast furnace charging raw materials is charged inside a sintering raw material bed in a dispersed state, and is sintered together with the other sintering raw material, is used. Preferably, the charging raw material of coarse grains is iron ore and/or steel making slag, and the charging raw material of coarse grains is charged inside the sintering raw material bed in such a manner that the average spacing is controlled to 40 to 80 mm. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a sintered ore used when producing a sintered ore using a downward suction droidoid type sintering machine.

  When producing sintered ore from powdered iron ore, etc., powdered iron ore is blended with powdered coke, which is a carbonaceous material as fuel, and limestone, as an auxiliary material. A sintered raw material bed is formed by charging into a sintering pallet, the surface layer of the sintered raw material bed is ignited and sintered, and this is crushed and sized to obtain a sintered ore. Crushing is performed on a sintered ore cake (also called a sinter cake) that has been sintered with a sintering machine, and the sintered ore cake is detached from the sintering pallet at the discharge end of the sintering machine. At the stage of dropping onto the crushing guide, this is primarily crushed by a crusher and further supplied to a sinter cooler to be cooled to obtain a sinter. Coarse sintered ore with a particle size of 100 mm or more is not suitable for blast furnace charging because it is difficult to control reductive delay and filling control in the blast furnace. The particle size is adjusted to the particle size. In addition, fine particles with a particle size of 3 to 5 mm or less are filled with high density in the blast furnace to reduce the air permeability and inhibit the reduction. Used as a raw material.

  In the conventional manufacturing process of sintered ore, there is a problem that a large amount of powdered sintered ore occurs during the crushing by the crusher, resulting in a decrease in yield.

  Therefore, conventionally, various proposals have been made from the viewpoint of preventing pulverization to generate cracks to assist crushing in the sintered ore cake during the crushing.

  For example, in Patent Document 1, a groove extending in the pallet traveling direction is formed at a constant interval on the surface of the sintering raw material bed, and other raw materials are put in the groove to keep the air permeability constant, and irregular by baking Proposals have been made for cracks to be gathered in advance in a groove where other raw materials are placed, to suppress air leakage, to prevent uneven burning, to facilitate crushing from the groove as a starting point, and to improve yield.

  Moreover, in patent document 2, the groove | channel of a fixed interval is formed in the sintering raw material bed surface with a convex roller, and the firing time in a surface part is extended by applying a closeness, and the crack which arises in a surface part Proposals have been made to disperse the particles to facilitate crushing and improve the yield.

  Further, in Patent Document 3, a slit is formed in a layer in the vertical direction and / or the horizontal direction inside the sintering material bed after charging the sintering material into the sintering pallet and before the ignition furnace, and fuel is supplied to the slit. Proposals have been made to suppress the generation of powder by charging an inorganic raw material not contained and easily crushing with a slit after firing.

On the other hand, although different from the viewpoint of generating cracks to assist crushing in the sintered ore cake, as a method that may have the same effect, a sintered raw material bed having a particle diameter of 10 to 20 mm is used. A technique for mixing a floor bedding ore, which is a ore, is known (for example, see Patent Document 4). By mixing 2.5 to 10% by mass of a large-particle-size bedding ore into the sintered raw material bed, the air permeability of the sintered raw material bed can be improved and the sintered ore can be produced with high productivity. It is said that.
JP-A-57-13128 JP-A-4-259335 JP-A 61-195926 Japanese Patent Laid-Open No. 10-72627

  However, the conventional techniques described in Patent Documents 1 and 2 are all effective only in a limited portion of the surface of the sintering material bed, and the yield of most of the sintered ore cake There is no effect. Furthermore, in practice, when grooves are formed on the surface of the sintering material bed, it is difficult to suppress the promotion of the gas velocity flowing into the grooves even when other raw materials are supplied to the grooves. The peripheral part becomes unevenly burned and the yield decreases. In addition, the strength of the surface layer of the sintered ore cake was lower than that of the lower part, and on the contrary, there was a problem of promoting pulverization.

  Furthermore, the prior art described in Patent Document 3 penetrates the sintering raw material bed at intervals of several tens of centimeters and forms a non-uniform layer continuous in the length direction of the sintering machine. In comparison with the prior art described in (1), a larger non-uniform air permeability was introduced into the sintering material bed, and the uneven burn area was enlarged in the periphery of the slit, resulting in a problem of lowering the yield.

  As described above, in the techniques described in Patent Documents 1 to 3, a crack that assists crushing is generated in the sintered ore cake, and powdering of the sintered ore at the time of crushing is prevented to prevent a decrease in yield. There is a problem that it is difficult.

  On the other hand, the means for mixing a large amount of bedstone ore within the product grain size range of the sintered ore into the sintering material bed eliminates raw new raw material that has not been fired from the sintering material bed. If the production rate is not increased beyond the amount of mixed ore, it will be effective, it will be difficult to maintain strength, and it will be uneconomical. In addition, if a large amount of coarse particles are introduced, the coarse lump of the sintered product increases, the ratio of processing in the secondary crushing process increases, excessive crushing is required, and the yield is not improved. is there.

  Therefore, an object of the present invention is to solve the problems of the prior art, prevent pulverization at the time of crushing when manufacturing sintered ore, and improve the yield. It is to provide.

  The inventors of the present invention focused on mixing coarse particles other than bedding ore into the sintering raw material bed in solving the above problem. That is, it is the use of a coarse charged raw material having a particle size of 10 mm or more and 20 mm or less selected from blast furnace charged raw materials. In the present invention, by mixing the coarse charge raw material in the sintering raw material bed, focusing on the existence of the coarse charge raw material as a crack initiation point that facilitates crushing, The present invention has been completed.

That is, the present invention has the following characteristics.
(1) A coarse charged material having a particle diameter of 10 mm or more and 20 mm or less selected from blast furnace charged raw materials is charged in a dispersed state in a sintered raw material bed and sintered together with other sintered raw materials. A method for producing sintered ore characterized by the above.
(2) The method for producing sintered ore according to (1), wherein the coarsely charged raw material is iron ore and / or steelmaking slag.
(3) The method for producing a sintered ore according to (1) or (2), wherein a coarsely charged raw material is charged into a sintered raw material bed so that an average interval is 40 to 80 mm. .
(4) In the region of 75% layer thickness below the sintering raw material bed, the coarse charged raw materials are dispersed and sintered so as to have an average interval of 40 to 70 mm (1) to (3) ) Or a sintered ore production method according to any one of the above.
(5) When charging a sintering raw material containing a coarse charging raw material into a sintering raw material bed, a sloping chute arranged at a depression angle of 50 ° or more and less than 70 ° toward the sintering machine pallet traveling direction The method for producing a sintered ore according to any one of (1) to (4), wherein the method is used for charging.

  According to the present invention, without increasing the amount of sintered ore having a particle size of less than 5 mm (−5 mm) after crushing the sintered ore cake, the coarse ore of sintered ore having a particle size of 100 mm or more (+100 mm) is reduced. Sintering is possible because the amount of coarse ore sinter required for secondary crushing can be greatly reduced and the amount of sintered ore with a particle size of less than 5 mm generated by secondary crushing can be reduced. The yield of ore production can be greatly improved.

  First, the manufacturing process of a sintered ore is demonstrated using FIG. After mixing and granulating sintered raw materials containing powdered iron ore, carbonaceous material (coke coke), auxiliary raw materials (limestone, etc.), etc., using the raw material charging device 1, the sintering pallet of the sintering machine 2 The sintered raw material bed 3 is formed, and the surface layer of the sintered raw material bed 3 is ignited and sintered by the ignition device 4 to obtain a sintered ore cake 5. The sintered ore cake 5 is detached from the sintering pallet at the discharge end of the sintering machine 2, is primarily crushed by the crusher 6, is supplied to the sinter cooler 7, and is cooled to become sintered ore. The sintered ore is classified by the primary sieve 8, and the coarse sintered ore having a particle size of 100 mm or more is secondarily crushed by a secondary crusher 9 such as a roll crusher, and the particle size is adjusted to a particle size of 100 mm or less. The sintered ore whose particle size is adjusted to a particle size of 100 mm or less is classified by the screen 10, and one having a particle size of 3 to 5 mm or more is charged into the blast furnace 11 as a product sintered ore. Further, fine particles having a particle diameter of 3 to 5 mm or less are reused as the raw material 12 as a sintering raw material.

  The present invention can greatly reduce the amount of pulverization in the primary crushing described above, and in the production of sintered ore, the charging raw material selected from the blast furnace charging raw material is 10 mm or more and 20 mm or less. As a particle size, it is charged in a dispersed state as coarse particles in the sintering raw material bed, and mixed with other sintering raw materials and sintered to facilitate crushing at the time of crushing the sintered ore cake. As a starting point, by generating cracks at the time of crushing, the occurrence of powdering at the time of crushing is suppressed, and the yield of the sintered ore is improved. The coarse particles are selected from blast furnace charging materials. The reason for this is that when raw materials such as bedding ore described in the prior art are avoided as a charge to the sintering raw material bed, the original production of sinter is reduced. is there. In the present invention, even if charged into the blast furnace together with the sintered ore, there is no problem and the blast furnace charged raw material is charged into the sintered raw material bed as coarse particles.

  As the coarse-grained charging material selected from the blast furnace charging materials, those capable of maintaining the shape at the sintering temperature are preferable, and one or two or more types selected from the blast furnace charging materials are used. It is preferable to use iron ore, granular iron in slag generated from pretreatment and converter refining, steelmaking slag (converter slag) or limestone charged as an auxiliary material. Iron ore and / or steelmaking slag can be used particularly suitably because it contains a large amount of iron oxide to be reduced in a blast furnace and can easily obtain coarse particles having a desired particle size by classification.

  Moreover, as a coarse-grained charging raw material, it inserts and uses it as a coarse-grained material in a sintering raw material bed as a particle size of 10 mm or more and 20 mm or less for the reason mentioned later. A raw material having a particle size of 10 mm or more corresponds to coarse particles in the sintered raw material. However, if this coarse particle is used, the following phenomenon occurs in sintering.

  That is, when the coarse particles are dispersed in the sintering material bed, the firing condition changes around the coarse particles, and when coarse particles with low reactivity are used, the melt at the time of firing does not enter the lower portion of the coarse particles. Therefore, voids remain under the coarse particles.

  In the case of a sintered ore cake in which atmospheric pores remaining around the coarse grains or as traces after the reaction are moderately dispersed, the probability that the cracks progress and crushed so as to propagate through the voids increases. By introducing crack generation points in the sintered ore cake due to the presence of the sinter, it becomes possible to improve the grindability of the sintered ore cake and suppress powdering. As described above, the present inventors have found that the particle size distribution of the product sinter is influenced by the dispersion state of the voids in the sinter cake, as a result of intensive experiments. As described above, in the present invention, the reason why powdering (powder rate) at the time of crushing the sintered cake is reduced is that the cracks are introduced into the sintered ore cake due to the presence of coarse particles, and propagated through the air gap. As the crack progresses, it is crushed.

  As a result of further studies, the inventors have dispersed coarse particles in the sintering raw material bed so that the average interval between coarse particles is 40 mm to 80 mm. In the particle size distribution after primary crushing of the cake, it was found that the generation ratio of powder having a particle size of less than 5 mm (−5 mm) did not change, and coarse particles having a particle size of 100 mm or more (+100 mm) were reduced. The average interval between the coarse particles refers to the lattice interval obtained when the coarse particles are arranged at the lattice points of the cubic lattice assumed in the sintering material bed, and is calculated from the target charging volume and the number of coarse particles. To do.

  The dispersion state of the coarse particles is preferably as close to uniform dispersion as possible, and even if the dispersion state is analyzed for every region of the sintering raw material bed layer thickness, for example, the layer thickness of 10 cm, it corresponds to this average interval in each region. This means that a large number of coarse particles are dispersed, and it does not mean that a considerable number of coarse particles are contained when viewed in the whole bed.

  As described above, since the +100 mm coarse block undergoes a secondary crushing process, the crushing inevitably generates a return of -5 mm, thereby reducing the yield of the product sintered ore. However, in the present invention, since +100 mm can be reduced without changing the generation amount of −5 mm in the primary crushing stage, there is no occurrence of return ore due to additional crushing, and the yield of sintered products can be greatly improved. Become.

It is preferable to use a raw material having low reactivity as a raw material charged with coarse particles selected from blast furnace raw materials, and coarse particles of fine ore (particle size 10 to 15 mm) or recycled materials in steelworks. It is preferable to use the steelmaking slag (so-called converter slag) added as Since the sintered ore produced in the present invention is for blast furnace charging, the components include iron oxide (Fe ₂ O ₃ , Fe ₃ O ₄ , FeO) and metallic iron, CaO, SiO ₂ , Al ₂ O ₃ , It is desirable to use a material whose content of components other than MgO and C is 10 mass% or less.

  The coarse-grained charging material selected from the blast furnace charging materials has a particle size of 10 to 20 mm, particularly preferably 10 to 15 mm. This is because coarse particles having a particle size exceeding 20 mm have a large inertial force applied to the coarse particles during charging, and the tendency to segregate downward cannot be suppressed, making it difficult to achieve a dispersed state. For this reason, when the horizontal cross section in the sintered raw material bed is assumed, the occupied area of the cross section of the dense particles that hinders the air flow increases and the air permeability of the bed is lowered. On the other hand, when the particle size is smaller than 10 mm, the reaction with the melt generated in the surroundings proceeds, and the function of remaining as unreacted particles and forming voids under the particles is lost.

  The reason why 40 to 80 mm is appropriate as the dispersion interval of the coarse particles is that if the distance exceeds 80 mm, the gap distance generated in the coarse particle portion is substantially long, and the crack propagation during crushing may not be affected. This is because the effect does not appear.

  Further, when the gap is close to less than 40 mm, the adjacent gaps are combined at the time of gap formation during firing, and the number of voids is reduced to easily generate huge continuous voids. For this reason, the mutual distance between the large continuous voids increases, and a dense and strong structure in which small voids (for example, a spherical phase equal diameter of 10 mm or less) are reduced is generated between the huge continuous voids so as to propagate through the voids. This is because cracks do not progress and may result in an increase in coarse lumps after primary crushing.

  Coarse grains may be added to other raw materials before mixing and granulation of the blended raw materials of sintered ore, but less adhering powder to the coarse grains is better, after the primary mixed granulation process of other raw materials, For example, it is desirable to add it before it is put into the secondary mixer. In addition, when granulating with only one mixer, it can be added to the inside of the mixer in the latter half of the granulation.

  When charging the sintering raw material including the coarse charging raw material into the sintering raw material bed, the charging is performed using a sloping chute disposed at a depression angle of 50 ° or more and less than 70 ° toward the sintering machine pallet moving direction. It is preferable to enter.

  When using a method in which the sintering raw material is stacked in a predetermined layer thickness while sliding down the sintering raw material in the direction opposite to the pallet moving direction at the sintering raw material charging part of the sintering machine, the speed at which the raw material slides down the deposited raw material slope If not reduced, it is known that the particle size segregation in the raw material increases and the coarse particles tend to be unevenly distributed at the bottom of the bed.

  As a method of reducing this segregation, a method of charging the sintering raw material in the pallet traveling direction can be used. In this method, fine particles fall through the interparticle gap and fall down, and the coarse particles segregate upward, so that the lower particles can be offset and the coarse particles can be uniformly dispersed and charged. . The depression angle of the charging chute is desirably 50 to 70 °. This is because the angle of repose is 45 ° or more in the raw material in a wet state, and a further depression angle is necessary for continuous stable charging. In addition, the lower the angle is, the closer to the vertical, the more the raw material is compressed by gravity when the raw material is charged, and the porosity in the bed is lowered and the air permeability is deteriorated. This is because it is desired.

  It is preferable to disperse and sinter the coarse charged raw material at an average interval of 40 to 70 mm in the region of 75% layer thickness below the sintered raw material bed. If the dispersion interval of the coarsely charged raw material is in the range of 40 to 80 mm, a large amount of coarse particles are dispersed in the lower portion of the sintering raw material bed, resulting in a high temperature due to accumulation of calorific heat from the upper layer part. It is preferable because it is effective in the lower layer part that forms a dense and high-strength structure and easily generates coarse grains of 100 mm or more, and particularly in the region below the sintered raw material bed, It is preferable to disperse so as to have an average interval of 70 mm. The reason why the average interval between the coarsely charged raw materials is 40 to 70 mm in the region of 75% layer thickness below the sintering material bed is that the upper 25% layer thickness portion is lower in strength than the lower part, Since it is difficult to generate coarse grains, the density of coarse grains may be reduced from below, and conversely, increasing the density of coarse grains in the lower 75% layer thickness range, which tends to be excessive strength, This is because it is effective in reducing return ore. However, as described above, the coarse grains of +100 mm increase if the coarse interval is reduced to 35 mm or less even in the lower part.

  With reference to FIG. 2, one embodiment of the present invention will be described. FIG. 2 is a diagram for explaining a method of charging a coarse raw material dispersed in a sintered raw material bed, and is an example in the case of using crushed steel slag as the raw material. The steelmaking slag 20 is classified by a sieve 21, and those having a particle diameter of 10 mm or more are charged into the coarse slag tank 22 and those having a particle diameter of less than 10 mm are charged into the ore / auxiliary material tank 23. 24 is a lime tank, and 25 is a coke tank. Sintered raw materials cut out from the ore / auxiliary raw material tank 23, the lime tank 24, and the coke tank 25 are mixed into the primary mixer 26, mixed and granulated, and then the coarse steelmaking slag from the coarse slag tank 22. And secondary granulation is performed by the secondary mixer 27. The granulated material is charged into the surge hopper 28 and cut out by the roll feeder 29 while being charged into the sintering pallet 31 of the sintering machine using the chute 30 to form the sintering material bed 3. By arranging the chute 30 in the direction shown in FIG. 2 with respect to the traveling direction of the sintering pallet 31, the coarse charged raw material can be charged into the sintered raw material bed 3 in a dispersed state.

  In another embodiment, the coarsely charged raw material is charged downstream of the sintering pallet 31 in the traveling direction of the sintering pallet 31 in the surge hopper 28, By installing a hopper for charging raw materials or the like, even when charging the sintered raw materials into the sintering pallet 31, the coarse particles can be charged so as to slide under the charging slope, The coarsely charged raw material can be dispersed in the sintered raw material bed 3.

  Using raw materials having the chemical composition shown in Table 1, sinter ore production tests A to C were performed using the same equipment as shown in FIGS. Table 2 shows the basic mixing ratio of the raw materials.

  In this example, converter slag was used as a raw material for coarse particles. In Tables 1 and 2, the converter slag is shown as “LD slag”. When using converter slag, the particle size was adjusted according to the conditions of each test. Moreover, converter slag other than the coarse particle part to disperse | distribute was used as -10 mm. However, in the case where the average average coarse particle interval of the sintered raw material bed was 40 mm or less, the composition ratio was adjusted by increasing the blending ratio of the converter slag and operating other auxiliary raw materials.

  Using a downward suction droidoid type sintering machine, the sintering pallet width is 4.0 m, the sintering raw material bed layer thickness is 580 mm, and the sintering is adjusted according to the firing time at a standard pallet speed of 3.0 m / min. I did it.

  (Test A) Under the condition of an average interval of coarse particles of 60 mm, the coarse particle size is changed as shown in Table 3, dispersed in the sintering material bed, the sintered ore is fired, and the sintered ore The amount of -5 mm and +100 mm sintered ore after primary crushing and cooling of the cake was measured. The results are shown in Table 3 and FIG. The firing time is also shown in Table 3.

  When 5-10 mm converter slag was dispersed as coarse particles, the amount of +100 mm was large. When 20 to 25 mm was dispersed as coarse particles, the amount of +100 mm was large, and the sintering time was extended. When 10-15 and 15-20mm were disperse | distributed as a coarse particle, + 100mm part was reduced and the amount of secondary crushing was reduced significantly, with the amount for -5mm hardly changing.

  (Test B) The grain size of the converter slag coarse particles is 10 to 15 mm, and as shown in Table 4, the blending amount of the coarse particles is adjusted by changing the average interval of the coarse particles to 30 to 100 mm. Baked. The case where the coarse particles were not dispersed was fired as “no charge”. In addition, although the average interval of the coarse particles as a whole is 60 mm, the average interval is 57 mm in the lower portion 75% in the layer thickness direction of the sintering material bed, and the average interval is 70% in the upper portion 25%. In the case where segregates in the lower part, it was fired as “60 mm upper relaxation”. The amount of -5 mm and +100 mm sintered ore after primary crushing and cooling was measured. The results are shown in Table 4 and FIG.

  When coarse-grained converter slag was dispersed at an average interval of 40 to 80 mm, the amount of −5 mm was not changed and the amount of +100 mm was reduced, and the coarse ingot sintered ore was reduced. When coarse particles segregated in the lower part within an average interval of 40 to 80 mm, a tendency to decrease by -5 mm was observed compared to the case of uniform dispersion.

  (Test C) When charging the sintering raw material into the sintering raw material pallet, when the charging method is carried out by sliding down in the direction opposite to the direction of the sintering raw material pallet which is normally performed (in the opposite direction of the pallet), A comparison was made for the case of loading in the same direction as the pallet traveling direction (pallet direction). The average interval of coarse particles in the entire sintering material bed is about 40 mm, which is the same. However, as shown in FIG. In this charging, coarse particles were almost uniformly dispersed in the height direction of the sintering material bed. In addition, the layer thickness in FIG. 5 is a ratio with respect to the total sintering raw material layer thickness of the height from the flooring surface of a sintering raw material pallet. Sintering raw materials were charged under each charging condition, fired, and the amounts of -5 mm and +100 mm sintered ore after primary crushing and cooling were measured. The results are shown in FIG.

  In the charging in the opposite direction to the pallet, the segregation of the coarse particles in the lower part of the sintered raw material bed layer is large, and there is a segregated portion outside the range where the average interval of the coarse particles is 40 to 80 mm. However, although the coarse lumps of +100 mm are often produced, the coarse particles are uniformly dispersed in the layer thickness direction of the sintering raw material bed by charging in the pallet direction, and the production of coarse lumps of +100 mm is reduced.

Explanatory drawing of a sintering process. Explanatory drawing of one Embodiment of this invention. The graph which shows the result of the test A. The graph which shows the result of the test B. The graph which shows distribution of the average space | interval of the coarse grain in the height direction in a sintering raw material bed (test C). The graph which shows the result of the test C.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Raw material charging apparatus 2 Sintering machine 3 Sintering raw material bed 4 Ignition apparatus 5 Sintered ore cake 6 Crushing machine 7 Sintered ore cooling machine 8 Primary sieve 9 Secondary crushing machine 10 Screen 11 Blast furnace 12 Return ore 20 Steelmaking slag 21 Sieve 22 Coarse grain slag tank 23 Ore and auxiliary material tank 24 Lime tank 25 Coke tank 26 Primary mixer 27 Secondary mixer 28 Surge hopper 29 Roll feeder 30 Chute 31 Sinter pallet

Claims (5)

  A coarse charged material having a particle size of 10 mm or more and 20 mm or less selected from blast furnace charged materials is charged in a dispersed state in a sintered material bed and sintered together with other sintered materials. A method for producing sintered ore.   The method for producing a sintered ore according to claim 1, wherein the coarsely charged raw material is iron ore and / or steelmaking slag.   The method for producing a sintered ore according to claim 1 or 2, wherein a coarsely charged raw material is charged into a sintering raw material bed so that an average interval is 40 to 80 mm.   4. The sintered raw material bed is sintered by being dispersed so that the coarsely charged raw material has an average interval of 40 to 70 mm in a region of 75% layer thickness below the sintered raw material bed. A method for producing sinter ore.   When charging the sintering raw material including the coarse charging raw material into the sintering raw material bed, the charging is performed using a sloping chute disposed at a depression angle of 50 ° or more and less than 70 ° toward the sintering machine pallet moving direction. The method for producing a sinter according to any one of claims 1 to 4, wherein the sinter is produced.

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