JP7227053B2 - Method for producing sintered ore - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing sintered ore that is sintered using a downward suction sintering machine.

Sintered ore, which is the main raw material for blast furnace ironmaking, is generally produced in a production process having a downward suction Dwight Lloyd sintering machine as shown in FIG. Raw materials for sintered ore include fine iron ore (generally referred to as sinter feed of 8 mm or less), sintered ore under-sieve powder, recovered powder generated in steel mills, and CaO-containing secondary substances such as limestone and dolomite. They are raw materials, granulation aids such as quicklime, and carbon materials (coagulants) such as coke powder and anthracite. These raw materials are cut from each of a plurality of hoppers 1 onto a conveyor at a predetermined rate. Appropriate amounts of water are added to the cut raw materials by drum mixers 2 and 3, mixed and granulated into sintered raw materials, which are pseudo-particles having an average diameter of 3 to 6 mm.

The raw material for sintering is then charged from a surge hopper 5 disposed in the raw material feeding section of the sintering machine to a pallet 9 that circulates via a drum feeder 6 and a cutting chute 7, and is fed by a cut gate 8. A charge layer 10, also referred to as a sinter bed, with a thickness of 400-800 mm is formed. After that, the carbonaceous material on the upper surface of the charge layer 10 is ignited by the ignition furnace 11 arranged downstream of the raw material feeding section, and the By sucking the gas above the charge layer 10 downward, the carbonaceous material in the charge layer 10 is sequentially burned, and the sintering raw material is melted by the combustion heat generated at this time to obtain a sintered cake. The sintered cake thus obtained is then crushed, cooled, and granulated in the ore discharge section, and agglomerates having a size of about 5 mm or more are recovered as product sintered ore and supplied to the blast furnace.

In the above manufacturing process, the carbonaceous material in the charged layer 10 ignited by the ignition furnace 11 continues to burn with the gas sucked from the upper layer to the lower layer in the charged layer 10, and the pallet 9 is downstream. , the charge layer 10 gradually shifts from the upper layer to the lower layer, forming a combustion/melting zone (hereinafter also simply referred to as "combustion zone") having a width in the thickness direction. In FIG. 2, the carbonaceous material on the surface of the charge layer 10 ignited in the ignition furnace continues to burn with the sucked gas to form a combustion zone, which sequentially moves from the upper layer to the lower layer of the charge layer 10, After passing through the combustion zone, it is a diagram schematically showing the process of forming a sintered layer (sintered cake) in which the sintering reaction is completed.

The melted portion of the combustion zone obstructs the flow of the sucked gas, which causes the sintering time to be extended and the productivity to be lowered. In addition, as the combustion zone moves from the upper layer to the lower layer, the moisture contained in the sintering raw material is vaporized by the combustion heat of the carbonaceous material and concentrated in the sintering raw material in the lower layer, where the temperature has not yet risen. and form a wet zone. When the moisture concentration exceeds a certain level, the voids between the particles of the sintering raw material, which are the passages of the suction gas, are filled with moisture, which causes an increase in air flow resistance, as in the case of the combustion zone. FIG. 3 shows the combustion zone moving in the charging layer 10 with a thickness of 600 mm at a position of about 400 mm above the pallet in the charging layer 10 (200 mm below the surface of the charging layer 10). It shows the distribution of pressure loss (hereinafter referred to as pressure loss) and temperature in the charging layer 10. The pressure loss distribution at this time is about 30% in the wet zone and about 30% in the combustion zone. 40%.

The production volume (t/h) of the sintering machine is generally determined by the production rate (t/(h×m ² ))×sintering machine area (m ² ). That is, the production volume of the sintering machine depends on the specifications of the sintering machine (machine width, machine length), the thickness of the charging layer 10, the bulk density of the sintering raw material, the sintering (combustion) time, and the rate of product sintered ore. Determined by station, etc. Therefore, in order to increase the production of sintered ore, the thickness of the charging layer 10 is increased, the permeability (pressure loss) of the charging layer 10 is improved to shorten the sintering time, and the product sintered ore is produced. It is considered effective to increase the strength and improve the yield.

By the way, fine iron ore for sintering has been degraded in recent years due to depletion of high-quality iron ore. A decrease in the grade of high-quality iron ore leads to an increase in the slag component and a further reduction in the iron ore, and an increase in the alumina (Al ₂ O ₃ ) content and an increase in the fine powder ratio tend to reduce the granulability. ing. On the other hand, in blast furnaces, a low slag ratio is required from the viewpoint of reducing the production cost of hot metal and reducing the amount of _CO2 generated. ing.

In such an environment surrounding fine iron ore for sintering, high-quality sintered ore is produced using a pellet feed mainly composed of fine iron ore (particle size of 150 μm or less) that is difficult to granulate and has a low slag content. Techniques have been proposed for the production of For example, one of such conventional techniques is the Hybrid Pelletized Sinter method (hereinafter referred to as "HPS method"). This technology uses a drum mixer and a pelletizer to granulate iron ore, which contains a large amount of fine powder, such as pellet feed, granulation aids, and coagulants. Techniques for producing ore are disclosed in Patent Documents 1 to 5.

In addition, Patent Document 6 discloses a method for producing sintered ore by a multi-stage ignition sintering method, in which oxygen-enriched air is introduced into a charge layer downstream of an ignition furnace. there is

Japanese Patent Publication No. 2-4658 Japanese Patent Publication No. 6-21297 Japanese Patent Publication No. 6-21298 Japanese Patent Publication No. 6-21299 Japanese Patent Publication No. 6-60358 JP 2015-157980 A

However, in the method of granulating a pellet feed using the HPS method as described in Patent Documents 1 to 5, not only fine particles of less than 0.5 mm but also coarse particles of more than 10 mm are produced during granulation. generated a lot. Since the finer the grain, the larger the specific surface area, the pellet feed, which is a fine powder, preferentially absorbs moisture, resulting in quasi-particles in which fine powder is simply agglomerated, and grains in the form of fine powder attached around a core particle. They become coarse pseudo-particles with irregular diameters.

As described above, when a compounded raw material such as a pellet feed containing a large amount of fine iron ore having a particle size of 150 μm or less is granulated, the particle size becomes irregular and coarse pseudo-particles in which the fine powder is simply agglomerated are formed. is generated. Since such coarse quasi-particles have weak bonding strength, if they are deposited on a pallet of a sintering machine with a certain layer thickness, they will collapse when a load (compressive force) is applied, and the quasi-particles will be pulverized. This leads to a decrease in the porosity of the loading layer. As a result, the permeability of the charging layer is deteriorated, and the combustion of the sintering raw material is inhibited. As a result, the sintering time of the sintered ore becomes long, and the productivity of the sintered ore decreases. Further, if the sintering time is the same, the sintering will be insufficient, leading to a decrease in the yield of the sintered ore, and in this case also the productivity of the sintered ore will decrease.

In addition, even in the multi-stage ignition sintering method as described in Patent Document 6, when fine iron ore having a particle size of 150 μm or less is used in pellet feed or the like, the fine powder simply aggregates during granulation. The productivity of the sintered ore is lowered because coarse pseudo-particles are generated.

The present invention has been made in view of the above problems, and its object is to suppress the collapse of pseudo-particles and sinter when fine iron ore having a particle size of 150 μm or less is used as a sintering raw material. An object of the present invention is to provide a method for producing sintered ore capable of suppressing a decrease in ore productivity.

The features of the present invention for solving such problems are as follows.
(1) After forming a charging layer by charging sintering raw materials containing iron ore and carbonaceous material onto pallets that circulate in the raw material feeding section of the sintering machine, downstream of the raw material feeding section The charcoal material on the upper surface of the charging layer is ignited by the ignition furnace provided in the pallet, the gas above the charging layer is sucked by the wind box provided below the pallet, and the gas is passed to the charging layer. A method for producing sintered ore by introducing and burning the carbonaceous material in the charging layer to produce sintered ore, wherein the iron ore contains fine iron ore having a particle size of 150 μm or less, and the A method for producing sintered ore, comprising mixing part or all of fine iron ore as a molding with the sintering raw material.
(2) The method for producing sintered ore according to (1), wherein the iron ore contains 5% by mass or more and 50% by mass or less of fine iron ore, and 50% by mass or more of the fine iron ore is used as a molded product. .

By carrying out the method for producing sintered ore of the present invention, part or all of the fine iron ore is molded, so the generation of coarse pseudo-particles in which the fine iron ore aggregates is suppressed, and the sintered ore decrease in productivity is suppressed. In addition, since the method for producing sintered ore of the present invention can use a conventional sintering machine, it is possible to A sintered ore can be manufactured without lowering the productivity of the sintered ore.

It is a figure explaining the manufacturing method of a sintered ore. It is the figure which showed typically the process by which a sintered layer is formed. FIG. 4 is a diagram schematically showing the distribution of pressure loss and temperature in the raw material charged layer during sintering. 4 is a graph showing the difference in particle size distribution of pseudo-particles with and without pellet feed. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the manufacturing process of the sintered ore which can apply the manufacturing method of the sintered ore which concerns on this embodiment. It is a graph which shows the relationship between the fine powder ratio of 150 micrometers or less in particle size, and the production rate of a sintered ore.

In the present invention, part or all of fine iron ore having a particle size of 150 μm or less is molded to suppress deterioration of the permeability of the charging layer 10 due to pulverization of pseudo-particles, and sintered ore It is intended to suppress the decline in productivity. First, the characteristics of the raw material for sintering containing iron ore fine powder having a particle size of 150 μm or less will be described.

FIG. 4 is a graph showing the difference in particle size distribution of pseudo-particles with and without pellet feed. In FIG. 4, black plots indicate the particle size distribution of iron ore not blended with pellet feed, which is fine iron ore with a particle size of 150 μm or less. The white plot shows the particle size distribution of the iron ore whose particle size distribution is indicated by the black plot and 40% by mass of pellet feed, which is fine iron ore having a particle size of 150 μm or less.

When the pellet feed is blended at a ratio of 40% by mass as shown in FIG. 4, the particle size distribution indicated by black plots becomes the particle size distribution indicated by white plots. That is, by mixing the pellet feed at a ratio of 40% by mass, not only fine particles (less than 0.5 mm), but also many coarse (more than 10 mm) pseudo-particles were produced. If the wettability of fine iron ore is the same, the finer the iron ore, the larger the specific surface area and the more water it absorbs. Therefore, fine iron ore preferentially absorbs moisture with respect to coarse-grained iron ore that is not fine iron ore. Then, as the water is absorbed, the fine iron ore aggregates together to form coarse pseudo-particles simply aggregated from the fine iron ore. In the present embodiment, the particle size and ratio are determined by sieving the raw material into each particle size by sieving using a sieve with openings in accordance with JIS Z 8801-1, measuring the mass of each particle size, and measuring each particle size. The ratio of each particle size is calculated from the mass and the total mass. For example, "blending 40% by mass of a pellet feed with a particle size of 150 μm or less" means that the pellet feed passed through a sieve with a nominal opening of 150 μm in accordance with JIS Z 8801-1 is mixed with a ratio of 40 to the mass of the entire iron ore. %.

Coarse quasi-particles, which are agglomerates of such fine iron ore, have weak bonding strength, and when deposited on the pallet of a sintering machine, they collapse when a load (compressive force) is applied, and the quasi-particles are pulverized. to reduce the porosity of the loading layer 10 . As a result, the permeability of the charge layer 10 is deteriorated, and combustion of the sintering raw material is inhibited. As a result, the sintering time of the sintered ore becomes long, and the productivity of the sintered ore decreases.

Therefore, in the method for producing sintered ore according to the present embodiment, part or all of the iron ore fine powder having a particle size of 150 μm or less is used as a molding. This improves the bonding strength of the pseudo-particles and suppresses the disintegration of the pseudo-particles. As a result, deterioration of the permeability of the charging layer 10 due to pulverization of the pseudo-particles can be suppressed, and a decrease in productivity of the sintered ore can be suppressed.

As the carbonaceous material to be blended with the raw material for sintering, it is preferable to use a carbonaceous material having a particle size of less than 3 mm in an amount of 50% by mass or more. By using a carbonaceous material containing 50% by mass or more of particles having a particle diameter of less than 3 mm, the carbonaceous material can be segregated in the upper layer of the charging layer 10 and the combustibility can be enhanced, thereby promoting the sintering reaction of the charging layer 10. .

FIG. 5 is a schematic diagram showing a sintered ore manufacturing process to which the sintered ore manufacturing method according to the present embodiment can be applied. In FIG. 5, the same equipment as in FIG. 1 is given the same reference numerals, and redundant description is omitted. In the method for producing sintered ore according to the present embodiment, part or all of the iron ore fine powder having a particle size of 150 μm or less contained in the sintering raw material is cut out from the plurality of hoppers 1 and molded by the molding equipment 4. be. The molded fine iron ore is mixed with the sintering raw material granulated into pseudo-particles by drum mixers 2, 3 and the like. After that, the raw material for sintering is put into a circulating pallet 9 and sintered to produce a sintered ore. To the drum mixer 2 and the molding equipment 4, various raw materials can be independently discharged from a plurality of hoppers 1 in an arbitrary composition. Further, when molding the fine iron ore in the molding equipment 4, one or more of inorganic binders such as cement and bentonite and organic binders such as pitch, PVA, and alpha starch are added to improve the strength after molding. You may let Moreover, either one of the drum mixer 2 and the molding equipment 4, or a mixing equipment may be provided in front of both to perform stirring and mixing.

As described above, the method for producing sintered ore according to the present embodiment can be carried out using an existing sintering machine as it is by adding molding equipment 4 for molding fine iron ore. For this reason, the method for producing sintered ore according to the present embodiment suppresses a decrease in productivity of sintered ore from sintering raw materials containing fine iron ore having a particle size of 150 μm or less while using simple equipment. sintered ore can be produced.

As described above, when the iron ore used as the raw material for sintering contains a large amount of fine iron ore, coarse pseudo-particles with weak bonding strength, which are simply agglomeration of fine iron ore, are generated. When a large amount of fine iron ore having a particle size of 150 μm or less is contained, the effect of suppressing a decrease in productivity of sintered ore by the method for producing sintered ore of the present embodiment is increased. For this reason, in the method for producing sintered ore according to the present embodiment, it is preferable to add more than 10% by mass of fine iron ore having a particle size of 150 μm or less to iron ore as a raw material for sintering. In the present embodiment, iron ore means iron ore including fine iron ore with a particle size of 150 μm or less and coarse iron ore with a particle size of more than 150 μm. In addition, fine iron ore refers to all iron ore particles having a particle size of 150 μm or less, regardless of the brand of the ore.

Also, the ignition means of the ignition furnace 11 is not particularly limited, but it is preferable to use a burner using gaseous fuel such as C gas, B gas or M gas, which is a by-product gas of steelworks. A burner using gaseous fuel such as LNG, LPG, or city gas, which is often used in steelworks, may be used. Further, in order to ignite the coke fine or other condensate on the upper surface layer of the charged layer 10 in a short time, the oxygen concentration in the combustion-supporting gas supplied to the burner may be increased to raise the flame temperature of the burner. .

Further, gaseous fuel may be introduced into the upper layer portion of the charged layer 10 for the purpose of sufficiently securing the temperature required for sintering in the upper layer portion of the charged layer 10 . In this case, a gaseous fuel supply device having a hood is provided above the charge layer 10 in approximately 1/3 of the section from immediately after the ignition furnace 11 to the ore discharge section, and a gaseous fuel supply pipe is installed inside it. to supply gaseous fuel. Using this gaseous combustion supply device, an oxygen supply pipe may be arranged inside to supply oxygen gas to increase the oxygen concentration of the oxygen-enriched air. At least one of C gas, B gas, M gas, LNG, LPG and city gas may be used as the gaseous fuel.

A sintering experiment was conducted using a cylindrical sintering experimental apparatus (hereinafter referred to as a sintering pot) having an inner diameter of 300 mmφ and a height of 400 mm. The entire amount of fine iron ore having a particle size of 150 μm or less was mechanically compacted using a double roll briquette machine to form a 1.5 cc molding. The drop strength of the molded article was evaluated by the mass ratio of 5 mm or more in a 200 g molded article dropped from a height of 1 m. The mass ratio of the molded product of 5 mm or more was calculated by measuring the mass of the molded product that passed through a sieve with an opening of 5 mm after dropping, and dividing the mass by the mass of the entire molded product. . The drop strength of the molding used in this example was 52% by mass.

In this example, the fine iron ore was molded without using a binder, but the fine iron ore may be molded with a binder added. For example, by adding 1% by mass of pregelatinized starch and molding, the drop strength of the molding can be increased by about 1.5 times. As a result, it is possible to use conveying means that generate a strong impact, thereby improving the degree of freedom in designing the conveying equipment. In addition, even if a total of 25% by mass of auxiliary raw materials such as limestone, carbon materials, and sintered ore raw materials such as iron ore with a particle size larger than 150 μm is added to the fine iron ore, the drop strength is reduced by about 10%. Thus, even if the powdered iron ore was blended with a sintered ore raw material other than the powdered iron ore and molded, the drop strength of the molded product hardly decreased.

The strength of the molded product may be evaluated by crushing strength, but when evaluating whether or not the molded product will collapse due to the impact during transportation when the molded product contains moisture, it is not preferable to use the crushing strength. For example, for molded products with a particle size of about 10 to 15 mm, a molded product with a crushing strength of 5 kgf/p when dried with cement or the like, and a crushing strength of 1 kgf/p using starch or polyvinyl alcohol as a binder. When comparing certain moldings, the crushing strength of moldings using cement is higher. Conversely, the used molding becomes more expensive. A molded product using starch or polyvinyl alcohol as a binder is plastic in a wet state, and although it is plastically deformed when subjected to a drop impact, the particles are less likely to disintegrate. On the other hand, briquettes that are dried with cement or the like are brittle and break when subjected to a drop impact. In order to use the molded raw material in a sintering machine, it is necessary to withstand the drop impact due to the transfer of the belt conveyor from the drum mixer to the charging part of the sintering machine. Drop strength is preferred over strength.

Using a drum mixer with a diameter of 1 m, the sintering raw materials other than the molded product are rotated at 8 rpm for 300 seconds to form pseudo-particles, and the molded product is mixed at a predetermined ratio. Charged to thickness to form a charge layer, the upper surface of which was ignited by heating for 60 seconds using a propane-fueled burner, and suctioned from the bottom of the sintering pan at 700 mmAq to form a sinter cake. was made. In addition, 5% by mass of coke powder was added as a coagulant to the sintering raw material in which the pseudo-particles and the molding were mixed. Also, in all experiments, the raw material moisture content was adjusted to a constant average of 7.5% by mass.

In the above sintering experiment, the temperature of the flue gas discharged from the lower part of the sintering pot was measured, and the sintering time was defined as the time from ignition to the point when this temperature reached its peak. After the sintering experiment was completed, the sintered cake was dropped once from a height of 2 m, and the sintered ore remaining on the 10 mm sieve mesh was defined as the product. The yield of the sintered ore was calculated by dividing the mass of the product sintered ore having a size of 10 mm or more by the mass of the sintered cake. In addition, from the cross-sectional area (m ² ) of the sintering pot, the weight (t) of the product sintered ore, and the sintering time (h), the unit hearth area (m ² ), per unit time (h) A sintered ore production rate (t/(h×m ² )), which is a sintered ore production amount (t), was calculated.

The iron ore used in the sintering experiment is a coarse-grained iron ore with a grain size larger than 150 μm. Two iron ores were prepared that differed only in larger particle size. The chemical composition was 4.9% by weight of _SiO2 and 1.8% by weight _{of Al2O3} . The basicity (CaO/SiO ₂ ) of the raw material for sintering was adjusted to 2.0 by adjusting the amount of limestone. In addition, 20% by mass of sintered ore (return ore) having a diameter of 5 mm or less was added to simulate the sintering raw material used in an actual sintering machine. In the sintering experiment in which the molded fine iron ore was mixed, all of the fine iron ore was used as a molding.

FIG. 6 is a graph showing the relationship between the ratio of fine powder having a particle size of 150 μm or less and the production rate of sintered ore. In the graph shown in FIG. 6, the horizontal axis is the pulverization rate (% by mass) indicating the ratio of fine iron ore having a particle size of 150 μm or less in the iron ore, and the vertical axis is the production rate of sintered ore (t / (h×m ² )).

From FIG. 6, when fine iron ore is not molded, the production rate of sintered ore increases as the pulverization rate of iron ore with a particle size of 150 μm or less (hereinafter referred to as the pulverization rate) increases. decreased significantly. The sintered cake obtained by the sintering test with a fine powder ratio of 20% by mass was divided into three equal parts in the height direction, and the yield of the sintered ore was evaluated by dividing it into the upper layer, the middle layer and the lower layer, and the fine powder ratio was 10. The yield of sintered ore in the upper layer was greatly reduced compared to the sintering test in which mass % was used, and this was the cause of the decrease in the production rate of sintered ore.

Further, from FIG. 6, when the total amount of fine iron ore is used as a molded product, the fine powder ratio of 150 μm or less in the iron ore is set to 5% by mass or more, so that the fine iron ore of 150 μm or less is not included. The production rate of sintered ore increased. In addition, when the pulverization rate of iron ore having a particle size of 150 μm or less was 5% by mass or more and 50% by mass or less, the production rate of sintered ore increased as the pulverization rate increased. On the other hand, when the pulverization rate in iron ore was made higher than 50% by mass, the production rate of sintered ore slightly decreased. This is probably because the blending ratio of pulverized coal moldings increased, and the permeability of the charged layer became too high, conversely decreasing the yield, thereby decreasing the production rate of sintered ore.

If the iron ore contains fine iron ore with a particle size of 150 μm or less, coarse pseudo-particles that are merely agglomerated and have weak bonding strength are generated. Productivity drops. On the other hand, by molding fine iron ore with a particle size of 150 μm or less and including the molded product in the iron ore, the amount of sintered ore is lower than when iron ore that does not contain fine iron ore with a particle size of 150 μm or less is used. Since the production rate can be increased, sintered ore with a low slag ratio can be produced with high productivity using a pellet feed that is a difficult-to-granulate fine powder with a small slag component. Furthermore, by using the iron ore containing 5% by mass or more and 50% by mass or less of the molded fine iron ore having a particle size of 150 μm or less, the productivity of the sintered ore can be further increased.

In this example, an example was shown in which all of the iron ore fine powder having a particle size of 150 μm or less was molded, but the present invention is not limited to this. If at least a part of the fine iron ore is made into a molded product, pulverization of pseudo-particles can be suppressed more than when the fine iron ore is used as it is without molding, and a decrease in the production rate of sintered ore can be suppressed. Furthermore, the more the fine iron ore to be molded, the more the pulverization of pseudo-particles is suppressed, and the decrease in the production rate of sintered ore is suppressed. Molding is preferable, and it is more preferable to mold all of the fine iron ore having a particle size of 150 μm or less. When 50% by mass or more of the fine iron ore with a particle size of 150 μm or less is used as the molded product, the production rate of the sintered ore is the same as the “molding” and “no molding” in FIG. 6 regardless of the pulverization rate of the iron ore. The production rate is intermediate or higher, and is higher than the production rate when the pulverization rate is 0.

As described above, when iron ore containing fine iron ore having a particle size of 150 μm or less is used as a raw material for sintering, the fine iron ore is aggregated by using the method for producing sintered ore of the present embodiment. Deterioration of air permeability due to pulverization of pseudo-particles is suppressed, and a decrease in productivity of sintered ore can be suppressed. In addition, by making all of the iron ore fines into moldings, sintered ore with a low slag ratio can be produced at a high rate by using a sintering raw material containing a large amount of pellet feed, which is a fine powder that is difficult to granulate with a low slag content. Since the sintered ore can be produced with high elasticity, the use of the sintered ore as a blast furnace raw material can contribute to the reduction of the slag ratio in blast furnace operation.

1 Hopper 2 Drum Mixer 3 Drum Mixer 4 Molding Equipment 5 Surge Hopper 6 Drum Feeder 7 Cutting Chute 8 Cut Gate 9 Pallet 10 Charge Layer 11 Ignition Furnace 12 Wind Box

Claims (1)

A sintering raw material containing iron ore and carbonaceous material is charged onto a pallet that circulates in the raw material feeding section of the sintering machine to form a charged layer, and then the sintering raw material is arranged downstream of the raw material feeding section. The carbonaceous material on the upper surface of the charging bed is ignited in the ignition furnace, the gas above the charging bed is sucked by the wind box arranged below the pallet, and the gas is introduced into the charging bed. A sintered ore production method for producing sintered ore by burning the carbonaceous material of the charging layer,
The iron ore includes fine iron ore having a particle size of 150 μm or less,
All of the fine iron ore is mixed into the sintering raw material as a compacted compact,
The iron ore is pulverized based on the relationship between the production rate, which is the amount of sintered ore produced per unit time in a unit hearth area, and the pulverization rate, which is the ratio of the fine iron ore in the iron ore. containing the fine iron ore with the pulverization rate of 30% by mass or more and 50% by mass or less, in which the production rate increases as the rate increases,
A method for producing sintered ore.

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