WO2022049781A1 - 鉄鉱石ペレット及び鉄鉱石ペレットの製造方法 - Google Patents
鉄鉱石ペレット及び鉄鉱石ペレットの製造方法 Download PDFInfo
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- WO2022049781A1 WO2022049781A1 PCT/JP2020/036959 JP2020036959W WO2022049781A1 WO 2022049781 A1 WO2022049781 A1 WO 2022049781A1 JP 2020036959 W JP2020036959 W JP 2020036959W WO 2022049781 A1 WO2022049781 A1 WO 2022049781A1
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- iron ore
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B5/00—Making pig-iron in the blast furnace
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/16—Sintering; Agglomerating
- C22B1/216—Sintering; Agglomerating in rotary furnaces
Definitions
- the present invention relates to iron ore pellets and a method for producing iron ore pellets.
- the first layer containing the ore raw material and the second layer containing the coke are alternately laminated in the blast furnace, and the auxiliary fuel is blown into the blast furnace from the tuyere while the hot air is used to feed the ore raw material.
- a method of melting and producing pig iron is known. In this pig iron production method, the above-mentioned ore raw material supplied as iron ore pellets is reduced to produce pig iron. At this time, the coke mainly serves as a spacer for ensuring breathability.
- iron ore pellets having a pore volume of 0.01 cm 3 / g or more having a diameter of 10 ⁇ m or more have been proposed (see JP-A-63-219534).
- this iron ore pellet by controlling the amount of pores having a relatively large diameter, the decrease in crushing strength is suppressed, the pores are prevented from being blocked, and the overall porosity is increased.
- the present invention has been made based on the above circumstances, and an object of the present invention is to provide iron ore pellets having properties that enable further reduction of the amount of coke used in blast furnace operation.
- the iron ore pellet according to one aspect of the present invention is an iron ore pellet used for blast furnace operation, has a porosity of coarse open pores having a pore diameter of 4 ⁇ m or more of 21% or more, and a crushing strength of 180 kg / kg /. It is P or more.
- the porosity of the coarse open pores having a pore diameter of 4 ⁇ m or more is set to the above lower limit or more. Since only the open pores leading to the outside of the pellet contribute to the increase in the surface area of the iron ore pellet, the unit of the iron ore pellet that actually contributes to the reaction by controlling the porosity of the open pores. The surface area per weight can be increased directly. Further, since the iron ore pellet has a crushing strength equal to or higher than the above lower limit, it is difficult to pulverize it in the blast furnace during the operation of the blast furnace. Therefore, the iron ore pellets are highly reducing and can further reduce the amount of coke used in blast furnace operation.
- the "pore ratio of coarse open pores having a pore diameter of 4 ⁇ m or more” is the open pore ratio ⁇ 0 of iron ore pellets measured using a mercury intrusion porosity meter (for example, "Autopore III 9400" manufactured by Shimadzu Corporation). [%], Total pore volume A [cm 3 / g] per unit weight of iron ore pellets, Total pore volume A + 4 [cm 3 / g] with pore diameter of 4 ⁇ m or more per unit weight of iron ore pellets. When this is done, it is an amount calculated by ⁇ 0 ⁇ A + 4 / A [%].
- the open porosity is the ratio of the volume occupied by all open pores to the apparent volume of iron ore pellets.
- the content of fine powder having a particle size of 4.7 ⁇ m or less is preferably 8% by mass or more.
- the porosity of coarsely opened pores having a pore diameter of 4 ⁇ m or more can be improved and the crushing strength can be increased.
- the iron ore pellet has a fine powder agglutination structure.
- the aggregated structure of the fine powder refers to a state in which a plurality of dispersed fine particles are aggregated to form secondary particles, and specifically, 5 or more, preferably 10 or more fine particles are in contact with each other. Say the state of doing.
- the method for producing iron ore pellets according to another aspect of the present invention comprises a step of granulating raw pellets by adding granulating water to an iron ore raw material and a step of firing the raw pellets.
- the viscosity of the granulated water is 15 mPa ⁇ s or more.
- the viscosity of the granulated water when granulating raw pellets is set to be equal to or higher than the above lower limit. Iron ore pellets having a strength of 180 kg / P or more can be easily produced.
- viscosity refers to a value measured in accordance with JIS-Z8803: 2011 using a rotary viscometer.
- the granulated water contains an organic binder and the content of the organic binder in the raw pellet is 0.01% by mass or more and 1.0% by mass or less.
- the organic binder having a content within the above range in the granulated water in this way, a cohesive structure of fine powder can be formed in the produced iron ore pellets.
- the crushing strength can be increased while improving the porosity of the coarse open pores having a pore diameter of 4 ⁇ m or more in the iron ore pellets.
- the iron ore pellet of the present invention has a property that enables further reduction of the amount of coke used in blast furnace operation. Further, by operating the blast furnace using the iron ore pellets produced by the method for producing iron ore pellets of the present invention, the amount of coke used can be further reduced.
- FIG. 1 is a schematic plan view and a partially enlarged cross-sectional view showing iron ore pellets according to an embodiment of the present invention.
- FIG. 2 is a flow chart showing a method for producing iron ore pellets according to an embodiment of the present invention.
- FIG. 3 is a schematic diagram showing the configuration of a manufacturing apparatus used in the method for manufacturing iron ore pellets of FIG. 2.
- FIG. 4 is a graph showing the relationship between the porosity and the crushing strength of coarsely open pores having a pore diameter of 4 ⁇ m or more in the examples.
- FIG. 5 is a schematic cross-sectional view showing the configuration of a large load reduction experimental furnace in which the reduction rate was investigated in the examples.
- FIG. 1 is a schematic plan view and a partially enlarged cross-sectional view showing iron ore pellets according to an embodiment of the present invention.
- FIG. 2 is a flow chart showing a method for producing iron ore pellets according to an embodiment of the present invention.
- FIG. 3 is a schematic diagram
- FIG. 6 is a graph showing the temperature profile for heating the sample packed bed when the reduction rate was investigated in the examples.
- FIG. 7 is a graph showing the relationship between the temperature of the sample packed bed and the flow rate of the supplied gas.
- FIG. 8 is a graph showing the relationship between the porosity and the reduction rate of coarsely open pores having a pore diameter of 4 ⁇ m or more in the examples.
- the iron ore pellet 1 shown in FIG. 1 is an iron ore pellet used for blast furnace operation. Iron ore pellets are made by using pellet feed, iron ore fine powder, and auxiliary raw materials as needed to improve the quality to the properties suitable for blast furnace (for example, size, strength, reducing property, etc.). It is.
- the iron ore pellet 1 is mainly composed of coarse grains 11 which are pellet feeds and fine powder 12 which is a raw material for crushing iron ore, and a large number of pores 13 are formed inside.
- the iron ore pellet 1 may contain an auxiliary raw material. Examples of such auxiliary raw materials include limestone and dolomite.
- the size of the iron ore pellet 1 is appropriately determined according to the blast furnace or the like used, but for example, the particle size can be 10 mm or more and 25 mm or less.
- the coarse grain 11 for example, one containing one or a plurality of brands of fine grain pellet feed can be used.
- the coarse grain 11 refers to a grain having a particle size of 45 ⁇ m or more, and it is preferable that the coarse grain having a particle size of 0.5 mm or less occupies 90% by mass or more of the whole coarse grain 11. If the proportion of coarse particles having a particle size of 0.5 mm or less is less than the above lower limit, the surface area may be insufficient and the reducibility during blast furnace operation may decrease.
- the fine powder 12 for example, a pellet feed used as coarse particles 11 crushed by a crusher can be used.
- the fine powder 12 refers to grains having a particle size of less than 45 ⁇ m, and the lower limit of the content of the fine powder 12 having a particle size of 4.7 ⁇ m or less is preferably 8% by mass and 10% by mass with respect to the entire iron ore pellet 1. Is more preferable, and 20% by mass is further preferable.
- the content of the fine powder 12 having a particle size of 4.7 ⁇ m or less is not particularly limited, but may be, for example, 50% by mass.
- the iron ore pellet 1 has an aggregated structure 12a of fine powder 12.
- a plurality of fine particles 12 are aggregated and come into contact with each other to form secondary particles. That is, there is a region in the iron ore pellet 1 in which the density of the fine powder 12 is higher than the others.
- the fine powder 12 has the agglomerated structure 12a as described above, the strength of the agglomerated portion is increased, so that the crushing strength of the iron ore pellet 1 is improved.
- the agglomeration causes the fine powder 12 to be unevenly distributed, and the region where the fine powder 12 does not exist is also unevenly distributed. Therefore, the volume of one pore 13 described later tends to increase.
- the number of open pores 13a having a large pore diameter increases. Therefore, by having the aggregated structure 12a of the fine powder 12 in this way, the porosity of the coarse open pores having a pore diameter of 4 ⁇ m or more can be improved, and the crushing strength can be increased.
- the pores 13 include open pores 13a leading to the outside of the iron ore pellet 1 and closed pores 13b closed inside the pellets. That is, as shown in the enlarged cross-sectional view of FIG. 1, the open pore 13a is partially in contact with the surface of the iron ore pellet 1, while the closed pore 13b is surrounded by the coarse particles 11 and the fine powder 12. It has been.
- the porosity is determined by the volume ratio of all the pores 13 including the open pores 13a and the closed pores 13b, but among the pores 13 of the iron ore pellet 1, the ones that come into contact with the reducing gas in the blast furnace are the open pores. Since it is only 13a, the porosity of the open pores 13a is important in order to improve the reducibility of the ore raw material.
- the porosity when the porosity is constant, the smaller the pore diameter of the open pore 13a, the larger the surface area of the iron ore pellet 1.
- the open pore 13a if the pore diameter of the open pore 13a is small, it becomes difficult for the reducing gas to diffuse into the inside of the open pore 13a. Therefore, it is considered that the open pore 13a needs to have a pore diameter of a certain value or more.
- the porosity is increased, the crushing strength of the iron ore pellet 1 is lowered, which causes a disadvantage that it is easily pulverized in the blast furnace.
- the present inventors have found that the reducibility of the iron ore pellet 1 can be improved by controlling the porosity of the coarse open pores 13a having a pore diameter of 4 ⁇ m or more. That is, the lower limit of the porosity of the coarse open pore 13a having a pore diameter of 4 ⁇ m or more is 21%, more preferably 23%, still more preferably 25%. If the porosity of the open pores 13a is less than the above lower limit, the reducing property of the iron ore pellet 1 is insufficiently improved, and the amount of coke used in the blast furnace operation may not be sufficiently reduced.
- the upper limit of the porosity of the open pores 13a is set to a range in which the crushing strength does not fall below a certain value.
- the lower limit of the crushing strength is 180 kg / P, more preferably 190 kg / P, still more preferably 200 kg / P. If the crushing strength is less than the above lower limit, the iron ore pellet 1 is likely to be pulverized in the blast furnace, which may make the blast furnace operation difficult.
- the lower limit of the cumulative open pore volume of the coarse open pore 13a having a pore diameter of 4 ⁇ m or more is preferably 0.06 cm 3 / g, more preferably 0.07 cm 3 / g.
- the open pore diameter that maximizes the rate of change in the open pore volume is preferably 7 ⁇ m or more, and more preferably 8 ⁇ m or more.
- the porosity of the coarse open pores 13a having a pore diameter of 4 ⁇ m or more is 21% or more. Since only the open pores 13a leading to the outside of the pellets contribute to the increase in the surface area of the iron ore pellet 1, the iron ore that actually contributes to the reaction by controlling the porosity of the open pores 13a. The surface area per unit weight of the stone pellet 1 can be directly increased. Further, since the iron ore pellet 1 has a crushing strength of 180 kg / P or more, it is difficult to pulverize it in the blast furnace during the operation of the blast furnace. Therefore, the iron ore pellet 1 has high reducing property and enables further reduction of the amount of coke used in blast furnace operation.
- the iron ore pellet manufacturing method shown in FIG. 2 includes a granulation step S1, a firing step S2, and a cooling step S3, and the iron ore pellet 1 of the present invention shown in FIG. 1 can be manufactured.
- the method for producing the iron ore pellets can be performed using, for example, the Great Kiln-type manufacturing apparatus shown in FIG. 3 (hereinafter, also simply referred to as “manufacturing apparatus 2”).
- the manufacturing apparatus 2 includes a pan pelletizer 3, a great furnace 4, a kiln 5, and an anuracoola 6.
- raw pellets P are granulated by adding granulating water to the iron ore raw material. Specifically, after adding granulated water to the iron ore, the granulated water-containing iron ore is put into a panperetizer 3 which is a granulator and rolled to produce a mud dumpling-shaped raw pellet P.
- the iron ore is composed of coarse grains 11 and fine powder 12 constituting the iron ore pellet 1.
- the surface texture of iron ore differs greatly depending on the mining area and the crushing / transporting method, but the surface texture of iron ore is not particularly limited in the method for producing the iron ore pellets.
- the granulated water constitutes a water-based crosslink between the particles of the iron ore.
- the strength of the raw pellet P granulated in the granulation step S1 is maintained by the adhesive force acting between the particles due to this cross-linking. That is, the bond between particles is expressed by the surface tension of water existing between the particles, and the adhesive force between the particles is guaranteed by the value obtained by multiplying this surface tension by the number of contacts between the particles.
- the lower limit of the viscosity of the granulated water is 15 mPa ⁇ s, more preferably 30 mPa ⁇ s, still more preferably 100 mPa ⁇ s. If the viscosity of the granulated water is less than the above lower limit, the crushing strength of the produced iron ore pellet 1 may be insufficient.
- the upper limit of the viscosity of the granulated water is not particularly limited, but can be, for example, 10000 mPa ⁇ s.
- the granulated water may contain an organic binder.
- organic binder those having a molecular weight of 104 or more and 108 or less, more preferably those having a molecular weight of 104 or more and 106 or less are used, and specific examples thereof include cornstarch, tapioca, potatoes and guar beans. be able to.
- this organic binder if the iron ore is sufficiently water-retaining, only the organic binder may be added according to the water-retaining amount. On the contrary, when the iron ore does not retain water, granulated water having a desired viscosity may be added by blending an organic binder with the water. When it is in the middle, the water retention amount of the iron ore is taken into consideration, and the amount of the organic binder blended is determined so that the viscosity of the added granulated water becomes a desired viscosity. In this case, the organic binder may be blended with respect to the water content of the iron ore. That is, the addition of water to the iron ore and the blending of the organic binder may be performed at the same time.
- the lower limit of the content of the organic binder in the raw pellet P is preferably 0.01% by mass, more preferably 0.1% by mass.
- the upper limit of the content of the organic binder is preferably 1.0% by mass, more preferably 0.2% by mass. If the content of the organic binder is less than the above lower limit, the aggregated structure 12a of the fine powder 12 may not be sufficiently formed on the produced iron ore pellet 1 and the crushing strength may be insufficient. On the contrary, when the content of the organic binder exceeds the above upper limit, the improvement of the porosity of the coarse open pores having a pore diameter of 4 ⁇ m or more of the iron ore pellet 1 tends to be saturated, and the effect on the increase of the raw material cost is insufficient. There is a risk of becoming.
- the lower limit of the water content in the raw pellet P is preferably 7.0% by mass, more preferably 8.0% by mass.
- the upper limit of the water content is preferably 11.0% by mass, more preferably 10.0% by mass. If the water content is less than the lower limit, the cross-linking structure between the particles of the iron ore due to water may be insufficient, and the crushing strength may be insufficient. On the contrary, if the water content exceeds the upper limit, the porosity of the coarse open pores having a pore diameter of 4 ⁇ m or more in the iron ore pellet 1 may not be sufficiently improved.
- the great furnace 4 includes a traveling great 41, a drying chamber 42, a water separation chamber 43, and a preheating chamber 44.
- the traveling great 41 is configured to be endless, and the raw pellets P placed on the traveling great 41 can be moved in the order of the drying chamber 42, the water separation chamber 43, and the preheating chamber 44.
- the raw pellet P is dried, separated, and preheated by the downward ventilation of the heating gas G1, and the raw pellet P is given strength to withstand the rolling in the kiln 5.
- the raw pellet P is dried at an atmospheric temperature of about 250 ° C.
- the temperature of the dried raw pellet P is raised to about 450 ° C., and water of crystallization mainly in iron ore is decomposed and removed.
- the temperature of the raw pellet P is raised to about 1100 ° C., carbonates contained in limestone, dolomite and the like are decomposed to remove carbon dioxide, and magnetite in iron ore is oxidized. As a result, the preheated pellet H is obtained.
- the heating gas G1 in the drying chamber 42 As shown in FIG. 3, as the heating gas G1 in the drying chamber 42, the heating gas G1 used in the water separation chamber 43 is diverted. Similarly, the heating gas G1 of the preheating chamber 44 is diverted to the heating gas G1 of the water separation chamber 43, and the combustion exhaust gas G2 used in the kiln 5 is diverted to the heating gas G1 of the preheating chamber 44. By diverting the high-temperature heating gas G1 or the combustion exhaust gas G2 on the downstream side in this way, the heating cost of the heating gas G1 can be reduced.
- a burner 45 may be provided in each chamber to control the temperature of the heating gas G1. In FIG. 3, a burner 45 is provided in the water separation chamber 43 and the preheating chamber 44. Further, the heating gas G1 used in the drying chamber 42 is finally discharged from the chimney C.
- the kiln 5 is directly connected to the great furnace 4 and is a cylindrical rotary furnace with a gradient.
- the kiln 5 fires the preheated pellet H discharged from the preheating chamber 44 of the great furnace 4.
- the preheated pellet H is calcined at a temperature of about 1200 ° C. by combustion with a kiln burner (not shown) arranged on the outlet side. As a result, the high temperature iron ore pellet 1 is obtained.
- the atmosphere which is the cooling gas G3 used in the anuracoola 6, is used as the combustion air. Further, the high-temperature combustion exhaust gas G2 used for firing the preheating pellet H is sent to the preheating chamber 44 as a heating gas G1.
- the cooling step S3 the high-temperature iron ore pellet 1 obtained in the firing step S2 is cooled.
- the annular cooler 6 is used.
- the iron ore pellet 1 cooled in the cooling step S3 is accumulated and used for blast furnace operation.
- the iron ore pellet 1 can be cooled by ventilating the atmosphere through the air ventilator 61, which is the cooling gas G3, while moving the high-temperature iron ore pellet 1 discharged from the kiln 5.
- the cooling gas G3 used in the anuracoola 6 and whose temperature has risen is sent to the kiln 5 and used as combustion air.
- the viscosity of the granulated water when granulating the raw pellets P is 15 mPa ⁇ s or more, so that the porosity of the coarse open pores having a pore diameter of 4 ⁇ m or more is 21% or more.
- the iron ore pellet 1 of the present invention having a crushing strength of 180 kg / P or more can be easily produced.
- the iron ore pellet is composed of coarse particles and fine powder
- the iron ore pellet composed of only coarse particles or only fine powder is also an object of the present invention.
- Example 1 Example 1, Example 2, Comparative Example 1
- the iron ore pellets of Example 1, Example 2 and Comparative Example 1 were produced according to the method for producing iron ore pellets shown in FIG.
- the granulated water contained an organic binder in Examples 1 and 2, and the content of the organic binder was 0.1% by mass in Example 1 and 0.2% by mass in Example 2. As a result, the viscosity of the granulated water was 17.4 mPa ⁇ s in Example 1 and 31.7 mPa ⁇ s in Example 2.
- the organic binder used was a starch-based organic binder (a mixture of 60% by mass of cornstarch, 30% by mass of tapioca, and 10% by mass of potatoes, to which 10% by mass of Bennite was added). The viscosity was measured using a rotary viscometer in accordance with JIS-Z8803: 2011.
- the granulated water of Comparative Example 1 did not contain an organic binder.
- the viscosity of the granulated water was 1 mPa ⁇ s.
- Example 2 For the iron ore pellets of Example 1, Example 2 and Comparative Example 1, the porosity of coarsely open pores having a pore diameter of 4 ⁇ m or more and the crushing strength were measured.
- the above-mentioned coarse open porosity is the open porosity ⁇ 0 [%] of iron ore pellets measured using a mercury intrusion porosity meter (“Autopore III 9400” manufactured by Shimadzu Corporation), and the total fineness per unit weight of iron ore pellets.
- the porosity of the coarse open pores having a pore diameter of 4 ⁇ m or more was 21% or more. It can be seen that iron ore pellets having a crushing strength of 180 kg / P or more can be easily produced. On the other hand, in the iron ore pellet of Comparative Example 1 in which the viscosity of the granulated water is less than 15 mPa ⁇ s, it can be seen that both the porosity and the crushing strength of the coarse open pores having a pore diameter of 4 ⁇ m or more are low.
- FIG. 5 shows the large load reduction experimental furnace 7 used in this experiment.
- the inner diameter of the graphite crucible 71 filled with the sample was ⁇ 85 mm.
- the sample packed layer 72 was composed of an upper coke layer 72a (height 20 mm), an ore layer 72b (height 150 mm), and a lower coke layer 72c (height 40 mm) from the top.
- the ore layer 72b was a mixture of sinter (grain size 16 to 19 mm), the above iron ore pellets (grain size 11.2 to 13.2 mm), and lump ore (grain size 16 to 19 mm).
- the sample packed bed 72 was heated with the temperature profile shown in FIG. 6 using an electric furnace 73, and the gas (reducing gas) having the composition shown in FIG. 7 was supplied.
- the gas was supplied from the gas supply pipe 74 provided in the lower part of the large load reduction experimental furnace 7 and discharged from the gas discharge pipe 75 provided in the upper part.
- the total amount of the gas supplied was 51.3 NL / min, and the temperature was controlled by two thermocouples 76.
- the load applied to the sample packed bed 72 was 1 kgf / cm 2 . This load was added by adding the weight of the weight 78 via the load rod 77.
- the reduction rate was measured twice. The results are shown in FIG. In the graph of FIG. 8, the result of each of the two trials is shown by a bar, and the average value is shown by a dot. From the results shown in FIG. 8, it can be seen that the use of the iron ore pellets of the present invention enhances the reducing property and further reduces the amount of coke used in the blast furnace operation.
- the iron ore pellet of the present invention has a property that enables further reduction of the amount of coke used in blast furnace operation. Further, by operating the blast furnace using the iron ore pellets produced by the method for producing iron ore pellets of the present invention, the amount of coke used can be further reduced.
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Abstract
Description
図1に示す鉄鉱石ペレット1は、高炉操業に用いられる鉄鉱石ペレットである。鉄鉱石ペレットとは、ペレットフィードと、鉄鉱石微粉と、必要に応じて副原料とを用い、高炉用に適した性状(例えばサイズ、強度、還元性など)に、品質を向上させて作り込んだものである。
当該鉄鉱石ペレット1は、気孔径が4μm以上の粗大開気孔13aの気孔率を21%以上とする。当該鉄鉱石ペレット1の表面積の増大に寄与するのは、ペレットの外部まで通じている開気孔13aのみであるので、この開気孔13aの気孔率を制御することで、実際に反応に寄与する鉄鉱石ペレット1の単位重量当たりの表面積を直接的に大きくすることができる。また、当該鉄鉱石ペレット1は、圧潰強度を180kg/P以上とするので、高炉操業時に高炉内で粉化し難い。従って、当該鉄鉱石ペレット1は、還元性が高く、高炉操業においてコークスの使用量のさらなる削減を可能とする。
図2に示す鉄鉱石ペレットの製造方法は、造粒工程S1と、焼成工程S2と、冷却工程S3とを備え、図1に示す本発明の鉄鉱石ペレット1を製造することができる。当該鉄鉱石ペレットの製造方法は、例えば図3に示すグレートキルン方式の製造装置(以下、単に「製造装置2」ともいう)を用いて行うことができる。製造装置2は、パンペレタイザ3と、グレート炉4と、キルン5と、アニュラクーラ6とを備える。
造粒工程S1では、鉄鉱石原料への造粒水の添加により生ペレットPを造粒する。具体的には、鉄鉱石に造粒水を添加した後、この造粒水含有鉄鉱石を造粒機であるパンペレタイザ3に投入及び転動させて、泥団子状の生ペレットPを製造する。
焼成工程S2では、生ペレットPを焼成する。焼成工程S2では、グレート炉4及びキルン5が用いられる。
グレート炉4は、図3に示すように、トラベリンググレート41と、乾燥室42と、離水室43と、予熱室44とを備える。
キルン5は、グレート炉4に直結されており、勾配をつけた円筒状の回転炉である。キルン5は、グレート炉4の予熱室44から排出される予熱ペレットHを焼成する。具体的には出口側に配設されたキルンバーナ(不図示)による燃焼により予熱ペレットHを1200℃程度の温度で焼成する。これにより高温の鉄鉱石ペレット1が得られる。
冷却工程S3では、焼成工程S2で得られる高温の鉄鉱石ペレット1を冷却する。冷却工程S3では、アニュラクーラ6が用いられる。冷却工程S3で冷却された鉄鉱石ペレット1は集積され、高炉操業に用いられる。
当該鉄鉱石ペレットの製造方法では、生ペレットPを造粒する際の造粒水の粘度を15mPa・s以上とするので、気孔径が4μm以上の粗大開気孔の気孔率が21%以上であり、圧潰強度が180kg/P以上である本発明の鉄鉱石ペレット1を容易に製造することができる。
なお、本発明は、上記実施形態に限定されるものではない。
図2に示す鉄鉱石ペレットの製造方法に従って、実施例1、実施例2及び比較例1の鉄鉱石ペレットを製造した。
造粒水としては、実施例1及び実施例2では有機バインダを含むものとし、有機バインダの含有量を、実施例1では0.1質量%とし、実施例2では0.2質量%とした。その結果、造粒水の粘度は、実施例1で17.4mPa・s、実施例2で31.7mPa・sとなった。使用した有機バインダは、デンプン系の有機バインダ(コーンスターチ60質量%、タピオカ30質量%、馬鈴薯10質量%を混合した原料にベンナイトを外数で10質量%加えたもの)である。また、粘度の測定は、回転式粘度計を用いてJIS-Z8803:2011に準拠して行った。
上記生ペレットを炉へ装入し、温度1210℃で15分間の焼成を行った。なお、雰囲気には、空気3LにN2ガス1Lを混合したものを用いた。また、昇温時間及び冷却時間はともに10分間とした。
実施例1、実施例2及び比較例1の鉄鉱石ペレットを用いて、高炉周辺部を模擬した大型荷重還元実験を行って、還元率を調査した。
11 粗粒
12 微粉
12a 凝集構造
13 気孔
13a 開気孔
13b 閉気孔
2 製造装置
3 パンペレタイザ
4 グレート炉
41 トラベリンググレート
42 乾燥室
43 離水室
44 予熱室
45 バーナ
5 キルン
6 アニュラクーラ
61 通風装置
7 大型荷重還元実験炉
71 黒鉛坩堝
72 試料充填層
72a 上部コークス層
72b 鉱石層
72c 下部コークス層
73 電気炉
74 ガス供給管
75 ガス排出管
76 熱電対
77 荷重棒
78 錘
P 生ペレット
H 予熱ペレット
G1 加熱用ガス
G2 燃焼排ガス
G3 冷却ガス
C 煙突
Claims (5)
- 高炉操業に用いられる鉄鉱石ペレットであって、
気孔径が4μm以上の粗大開気孔の気孔率が21%以上であり、
圧潰強度が180kg/P以上である鉄鉱石ペレット。 - 粒径4.7μm以下の微粉の含有量が8質量%以上である請求項1に記載の鉄鉱石ペレット。
- 微粉の凝集構造を有する請求項1又は請求項2に記載の鉄鉱石ペレット。
- 鉄鉱石原料への造粒水の添加により生ペレットを造粒する工程と、
上記生ペレットを焼成する工程と
を備え、
上記造粒水の粘度が15mPa・s以上である鉄鉱石ペレットの製造方法。 - 上記造粒水が有機バインダを含み、
上記生ペレットにおける上記有機バインダの含有量が0.01質量%以上1.0質量%以下である請求項4に記載の鉄鉱石ペレットの製造方法。
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SE2350133A SE2350133A1 (en) | 2020-09-03 | 2020-09-29 | Iron ore pellets and method for producing iron ore pellets |
BR112023002390A BR112023002390A2 (pt) | 2020-09-03 | 2020-09-29 | Pelotas de minério de ferro e método de produção de pelotas de minério de ferro |
CN202080103500.1A CN115989329A (zh) | 2020-09-03 | 2020-09-29 | 铁矿石球团及铁矿石球团的制造方法 |
CA3191576A CA3191576A1 (en) | 2020-09-03 | 2020-09-29 | Iron ore pellets and method for producing iron ore pellets |
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Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS55154534A (en) * | 1979-04-12 | 1980-12-02 | Kobe Steel Ltd | Iron ore porous pellet and its manufacture |
JPS56119742A (en) * | 1980-02-25 | 1981-09-19 | Kobe Steel Ltd | Manufacture of iron ore pellet |
JP2004076128A (ja) * | 2002-08-21 | 2004-03-11 | Nippon Steel Corp | 製鉄用造粒剤及びその製造方法 |
CN105441670A (zh) * | 2015-11-25 | 2016-03-30 | 北京首钢国际工程技术有限公司 | 一种链-回-环***生产高配比赤铁矿球团的工艺 |
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2020
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- 2020-09-29 CA CA3191576A patent/CA3191576A1/en active Pending
- 2020-09-29 CN CN202080103500.1A patent/CN115989329A/zh active Pending
- 2020-09-29 WO PCT/JP2020/036959 patent/WO2022049781A1/ja active Application Filing
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2023
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Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS55154534A (en) * | 1979-04-12 | 1980-12-02 | Kobe Steel Ltd | Iron ore porous pellet and its manufacture |
JPS56119742A (en) * | 1980-02-25 | 1981-09-19 | Kobe Steel Ltd | Manufacture of iron ore pellet |
JP2004076128A (ja) * | 2002-08-21 | 2004-03-11 | Nippon Steel Corp | 製鉄用造粒剤及びその製造方法 |
CN105441670A (zh) * | 2015-11-25 | 2016-03-30 | 北京首钢国际工程技术有限公司 | 一种链-回-环***生产高配比赤铁矿球团的工艺 |
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CL2023000628A1 (es) | 2023-09-15 |
JP7374870B2 (ja) | 2023-11-07 |
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CN115989329A (zh) | 2023-04-18 |
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