WO2013054471A1 - Method for granulation of sintering raw material - Google Patents

Method for granulation of sintering raw material Download PDF

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Publication number
WO2013054471A1
WO2013054471A1 PCT/JP2012/005794 JP2012005794W WO2013054471A1 WO 2013054471 A1 WO2013054471 A1 WO 2013054471A1 JP 2012005794 W JP2012005794 W JP 2012005794W WO 2013054471 A1 WO2013054471 A1 WO 2013054471A1
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Prior art keywords
iron ore
raw material
mass
particles
sintered
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PCT/JP2012/005794
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French (fr)
Japanese (ja)
Inventor
泰英 山口
上城　親司
尊三 川口
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新日鐵住金株式会社
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Application filed by 新日鐵住金株式会社 filed Critical 新日鐵住金株式会社
Priority to CN201280050273.6A priority Critical patent/CN103857809B/en
Priority to KR1020147012395A priority patent/KR20140079818A/en
Priority to JP2013538424A priority patent/JP5644955B2/en
Publication of WO2013054471A1 publication Critical patent/WO2013054471A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/16—Mills in which a fixed container houses stirring means tumbling the charge
    • B02C17/163—Stirring means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/18—Details
    • B02C17/183—Feeding or discharging devices
    • B02C17/1835—Discharging devices combined with sorting or separating of material
    • B02C17/184—Discharging devices combined with sorting or separating of material with separator arranged in discharge path of crushing zone
    • B02C17/1845—Discharging devices combined with sorting or separating of material with separator arranged in discharge path of crushing zone with return of oversize material to crushing zone
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B02—CRUSHING, PULVERISING, OR DISINTEGRATING; PREPARATORY TREATMENT OF GRAIN FOR MILLING
    • B02C—CRUSHING, PULVERISING, OR DISINTEGRATING IN GENERAL; MILLING GRAIN
    • B02C17/00—Disintegrating by tumbling mills, i.e. mills having a container charged with the material to be disintegrated with or without special disintegrating members such as pebbles or balls
    • B02C17/18—Details
    • B02C17/183—Feeding or discharging devices
    • B02C17/1835—Discharging devices combined with sorting or separating of material
    • B02C17/185—Discharging devices combined with sorting or separating of material with more than one separator
    • 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

Definitions

  • the present invention relates to a method for granulating a sintered raw material when producing a sintered ore used in a blast furnace, and in particular, even when increasing the blending ratio of hardly granulated fine iron ore as a sintering raw material.
  • the present invention relates to a method for granulating a sintered raw material capable of maintaining the productivity of the ore at low cost.
  • sintered ore used as an iron source in a blast furnace is manufactured as follows.
  • Various brands of iron ore, auxiliaries such as limestone, charcoal such as powdered coke, and return are mixed at a predetermined ratio to obtain a sintering raw material, and moisture is added to the sintering raw material, followed by mixing, humidity conditioning and granulation treatment.
  • the sintered raw material has a relatively large particle of about 3 to 5 mm as a core, and the core particle is finer than the core particle and surrounded by particles of 1 mm or less called “adhering powder”.
  • Granulated into small particles hereinafter also referred to as “pseudoparticles”.
  • the granulated sintered raw material is charged on a pallet of a sintering machine to form a sintered raw material packed layer (hereinafter also simply referred to as “filled layer”) on the pallet.
  • the packed bed is ignited on the upper surface thereof in an ignition furnace of the sintering machine, whereby the combustion of the carbonaceous material existing in the packed bed starts, and the combustion portion of the carbonized material forms a combustion zone. Since the packed bed is sucked from below, the combustion zone gradually moves from the upper part to the lower part of the packed bed. In the combustion zone, the surrounding pseudo particles are heated by the combustion heat and partially melted, and the pseudo particles are crosslinked and sintered by the melt. Thereby, the packed bed finally becomes a sintered cake.
  • the sintered cake is discharged from the sintering machine, crushed by a crusher, sized with a sieve, the sieve top becomes sintered ore, and the sieve below is returned to the sintered raw material as return ore.
  • the iron grade of sintered ore is deeply related to the operating results of the blast furnace, and further, from the viewpoint of environmental protection, it is strongly required to reduce the amount of CO 2 emitted from the blast furnace. It is important to manufacture. However, in recent years, high-quality fine iron ore as a sintering raw material has been depleted. Under these circumstances, in order to maintain the iron grade of sintered ore, the production form of sintered ore is to use a large amount of fine grade iron ore instead of high grade fine iron ore. Expected to be.
  • the high-grade fine iron ore mentioned here is based on the particle size distribution measurement method of iron ore specified in JIS (Japanese Industrial Standards) M 8716.
  • the ratio of the diameter is 250 ⁇ m or less) is 80% by mass or more, It refers to iron ore with Fe (total iron) of 60% by mass or more.
  • pellet feed iron ore whose iron grade has been improved by a beneficiation treatment can be mentioned.
  • Such high-quality fine iron ore is also simply referred to as “pellet feed” below.
  • the firing rate which is the rate at which the combustion zone moves from the upper part toward the lower part, decreases, and the productivity of the sintered ore deteriorates.
  • Non-Patent Document 1 the effect of improving the rate of adhesion of adhering powder due to quick lime is remarkable up to a blending ratio of quick lime of up to 2% by mass, but hardly changes even if blended beyond that.
  • quick lime is produced by industrially heating limestone to 900 ° C. or higher, and therefore requires high energy for production and high cost. Therefore, it is desirable to suppress the amount of quicklime used as much as possible.
  • Patent Document 1 At least one of dust collection dust, iron sand, maramamba ore, and pellet feed as an iron-based raw material with poor granulation property is blended in a total sintered raw material by 30% by mass or more, and the iron-based raw material is included.
  • a method for producing sintered ore is described in which moisture containing a surfactant is added and granulated together with other sintering raw materials. According to this method, the wettability of the iron-based raw material particles having the poor granulation property is improved, and as a result, the granulation and productivity of the sintered ore are improved.
  • Patent Document 2 describes a method of granulating a sintered raw material in which a slaked lime slurry produced by wet pulverizing quick lime is sprayed onto a sintered raw material in a granulator and added. According to this method, the productivity of sintered ore is improved as compared with adding dry lime after dry grinding.
  • Patent Document 3 in a selective granulation step in which a part of a sintering raw material is granulated in advance, at least one of a polymer compound such as polyacrylic acid and fine particles having an average particle diameter of 200 ⁇ m or less such as calcium carbonate is disclosed. Is added, and a granulated method of a sintered raw material in which hardly granulated maramamba ore or pellet feed is granulated and then mixed with the remaining sintered raw material is described.
  • a polymer compound such as polyacrylic acid and fine particles having an average particle diameter of 200 ⁇ m or less such as calcium carbonate
  • Patent Document 4 describes a method of forming raw material particles by adding and mixing iron ore ultrafine powder having an average particle size of 10 ⁇ m or less as a binder within a range of 2 to 15% by mass to sintered raw material particles. Yes.
  • tailings which are beneficiation residues generated at the base of iron ore, are used as the ultrafine iron ore powder having an average particle size of 10 ⁇ m or less.
  • Patent Document 5 describes a method for granulating a sintered raw material in which a sintered raw material containing iron ore is compressed and crushed by a roller press crusher and then granulated by adding a polyacrylic acid-based dispersant. .
  • a roller press crusher by processing the sintered raw material with a roller press crusher, a large amount of ultrafine particles having a particle size of 45 ⁇ m or less as a binder can be obtained, and pseudo-particles can be efficiently formed at the time of granulation, and the granulated product It is said that the strength of will improve.
  • An object of the present invention is to provide a method for granulating a sintered raw material that can ensure the air permeability of the layer and can maintain the productivity of the sintered ore at low cost.
  • the method for granulating a sintered raw material comprises mixing iron ore, carbonaceous material, auxiliary raw material and return mineral to obtain a sintered raw material, mixing the sintered raw material, adjusting the humidity and
  • the pulverizing unit is composed of a pulverizing unit composed of a cylindrical container having screw blades on a rotating vertical center axis, a classifying unit classified by the action of gravity and centrifugal force, and an underflow classified by the classifying unit.
  • An iron ore is wet pulverized using a vertical pulverizer having a circulation part that circulates in a cylindrical container, and the iron ore slurry formed by wet pulverization is added to all or part of the sintering raw material and granulated. It is characterized by that.
  • the sintering raw material has a ratio of particle size of 250 ⁇ m or less of 80% by mass or more, and T.I.
  • a specific brand of fine iron ore containing 60% by mass or more of Fe (total iron) is contained in at least the total sintered raw material in an amount higher than 13.20% by mass and lower than 20.00% by mass.
  • a portion of this sintering raw material that contains 50% by mass or more of the fine iron ore contains an amount of ultrafine particles having a particle size of 10 ⁇ m or less among the iron ores in the iron ore slurry. It is preferable to granulate by adding the iron ore slurry so as to be 0.01% by mass or more with respect to 1.0% by mass of the fine iron ore.
  • Specified brand fine iron ore here is, for example, high-quality South American pellet feed.
  • the iron ore is wet-ground using a vertical pulverizer, and the slurry in which the ultrafine particles of the iron ore of 10 ⁇ m or less obtained thereby are suspended is formed.
  • a sintering raw material as a binder for grains, sintering productivity can be maintained even if a large amount of pellet feed is blended as high-quality fine iron ore.
  • FIG. 1 is a graph showing the particle size distribution of pellet feed and fine iron ore.
  • FIG. 2 is an observation photograph of an iron ore crushed by a pulverizer using a scanning electron microscope (SEM).
  • FIG. 3 is a schematic diagram showing an overall configuration of a tower mill used for producing an iron ore slurry by the method for granulating a sintering raw material of the present invention.
  • FIG. 4 is a diagram showing the crushing strength test results of coarse pseudo-particles produced by changing the addition ratio of ultrafine particles.
  • FIG. 5 is a diagram showing the configuration of the granulation system in the embodiment of the present invention.
  • FIG. 6 is a diagram showing the evaluation results of the production rate of sintered ore by the pot sintering test.
  • ultrafine particles of iron ore having a particle diameter of 10 ⁇ m or less serve as a binder in granulation.
  • the detailed mechanism in which ultrafine particles act as a binder in granulation is as follows.
  • the added water serves as a binder that binds the core particles to the adhering powder, and this added water is combined with the core particles during the mixing, stirring, and granulation processes. It enters between the adhering powders and combines them.
  • ultrafine particles with a particle size of 10 ⁇ m or less contained in the sintering raw material can move freely with water when suspended in the added water, so the core particles and the adhering powder together with the added water. Get in between. In this way, the ultrafine particles fill the space between the core particles and the adhering powder to form a bridge, thereby increasing the strength of the pseudo particles.
  • P-type pseudo particles including the core particles and not including the core particles and having a total amount of 1 mm or less. Is also expected to develop.
  • a large amount of ultrafine particles as a binder is required, and when the P-type pseudo particles are charged on a pallet of a sintering machine as compared with normal pseudo particles.
  • the present inventors investigated the properties of the pellet feed, and the pellet feed is a fine powder raw material containing 80% by mass or more of particles having a particle size of 250 ⁇ m or less, and almost contains extremely fine particles of 10 ⁇ m or less. I have not found out. This is because the pellet feed improves the iron quality by performing a beneficiation process, specifically, grinding, polishing, washing, flotation, etc. at the mountain base, and ultrafine particles are removed in the process.
  • FIG. 1 is a graph showing the particle size distribution of pellet feed (PF.A) and three types of fine iron ore (SF.A, SF.B, SF.C).
  • the particle size distribution is measured by the wet sieving method of iron ore specified in JIS M 8716 for particles with a particle size exceeding 250 ⁇ m, and by the wet sieving method for particles having a particle size of 250 ⁇ m or less.
  • the fractionated water containing particles of 250 ⁇ m or less was collected, and this fractionated water was measured by a laser diffraction / scattering method defined in JIS R 1629.
  • the powdered iron ore has a particle content of more than 10 ⁇ m and not more than 250 ⁇ m with a PF. Although it is smaller than A, it contains about 10 to 15% of ultrafine particles of 10 ⁇ m or less.
  • T.A It contains 60% or more of Fe and has high quality.
  • Patent Document 3 uses calcium carbonate
  • Patent Document 4 uses tailings
  • Patent Document 5 uses iron ore crushed using a roller press as binders containing ultrafine particles.
  • a step of dispersing the ultrafine particles in water well and suspending them for example, by adding a polymer dispersant. Inferred to be indispensable.
  • the present inventors previously prepared a slurry in which ultrafine particles of iron ore are suspended in water (hereinafter also referred to as “iron ore slurry”) as an addition form of ultrafine particles, and the iron ore slurry is sintered. It was judged that the form to be added to the binding raw material is the best one that can obtain the binder effect at low cost.
  • the method for producing the iron ore slurry is preferably wet pulverization.
  • the pulverization of the iron ore and the suspension of the pulverized iron ore fine particles in water can be performed simultaneously, and the fine particles and water are well mixed without adding a dispersant.
  • a separate kneading / kneading step is required to further suspend the ultrafine particles obtained by pulverization in water.
  • powder iron ore is pulverized by wet pulverization, and by adding a slurry in which ultrafine particles of iron ore of 10 ⁇ m or less obtained by pulverization are suspended to the sintering raw material, a large amount of pellet feed is blended, It has been found that even when the fine powder ratio of the sintered raw material increases, the air permeability of the packed bed can be secured and the productivity of the sintered ore can be maintained at a low cost.
  • FIG. 2 is an observation photograph of the iron ore pulverized by a pulverizer using a scanning electron microscope (SEM).
  • A) and (b) are the cases of pulverization by the ball mill described in Patent Document 5, and
  • (c) and (d) are pulverized by the roller press described in the same document. Each case is shown as a comparative example.
  • E) and (f) of the same figure show the case where it grind
  • the respective magnifications are 500 times in FIGS. 2 (a), (c) and (e), and 3000 times in FIGS. 2 (b), (d) and (f).
  • FIG. 3 is a schematic diagram showing the overall configuration of a tower mill used for producing an iron ore slurry by the method for granulating a sintering raw material of the present invention.
  • the tower mill 1 is a vertical wet pulverizer, and is mainly composed of a pulverization unit, a classification unit, and a circulation unit.
  • the pulverizing unit is composed of a cylindrical container 4 provided with a double spiral screw blade 3 on a vertical center shaft 2 that is rotationally driven. In the cylindrical container 4, an iron ball is charged as a pulverizing medium.
  • the classification unit includes a water tank 5 connected to the upper side surface of the cylindrical container 4, and a cyclone classification device 6 connected to the water tank 5.
  • the circulation section includes a pipe 8 connected from the lower part of the water tank 5 to the lower part of the cylindrical container 4 through the circulation pump 7 and a pipe 9 connected from the lower part of the cyclone classifier 6 to the upper part of the water tank 5.
  • the iron ore to be crushed is thrown in from the upper part of the cylindrical container 4 together with water.
  • the charged iron ore falls to the lower part of the cylindrical container 4, and moves together with the iron balls in the cylindrical container 4 in the circumferential direction by the rotation of the screw blades 3 accompanying the rotational drive of the vertical center shaft 2.
  • the movement of being lifted up and wound upward and the movement of falling downward by its own weight are repeated.
  • a shearing force or a compressive force acts between the iron ores or between the iron ore and the iron ball, and the iron ore is crushed (crushed).
  • the iron ore In the cylindrical container 4, the iron ore is gradually reduced in size as the pulverization progresses, and when the speed at which the iron ore is wound upward by the rotation of the screw blades 3 is larger than the speed at which the iron ore falls in water due to its own weight, It is suspended in filled water to form a slurry and flows into the water tank 5 on the upper side surface of the cylindrical container 4.
  • the iron ore slurry that has flowed into the water tank 5 is roughly classified by the action of gravity.
  • the classified coarse iron ore slurry flows into the pipe 8 from the lower part of the water tank 5 as an underflow (see “U / F” in FIG. 3), passes through the circulation pump 7, and flows into the cylindrical container 4. It is returned to the lower part and pulverized again.
  • the fine-grain iron ore slurry flows into the cyclone classifier 6 as an overflow (see “O / F” in FIG. 3).
  • the iron ore slurry that has flowed into the cyclone classifier 6 is further finely classified by the action of centrifugal force.
  • the classified coarse iron ore slurry is returned to the upper part of the water tank 5 through the pipe 9 as an underflow (see “U / F” in FIG. 3), while the fine iron ore slurry Is discharged out of the tower mill 1 as an overflow (see “O / F” in FIG. 3).
  • iron ore and water are newly charged into the cylindrical container 4 by the amount of the iron ore slurry discharged out of the system.
  • the iron balls as the grinding media are gradually worn, they are appropriately put into the cylindrical container 4 together with the iron ore and replenished.
  • the tower mill 1 can continuously supply ultrafine particles of iron ore serving as a binder in granulation as a slurry suspended in water.
  • an iron ore slurry is used.
  • a slurry tank for temporarily storing the above may be installed.
  • the iron ore crushed by the tower mill has a remarkably smaller particle size than the iron ore crushed by the ball mill and roller press.
  • the container such as a ball mill which is a typical wet pulverizer other than the tower mill.
  • the iron ore crushed by the tower mill has a remarkably small particle size as compared with the case of using other pulverizers.
  • the shape of the ultrafine particles is more uneven when entering between the core particles and the adhering powder. It is assumed that the binder effect is high.
  • the surface of the iron ore crushed by the tower mill is more uneven than the iron ore crushed by the ball mill. It has a shape.
  • FIG. 4 is a diagram showing the crushing strength test results of coarse pseudo-particles produced by changing the addition ratio of ultrafine particles.
  • PF.A pellet feed
  • FIG. 4 is a diagram showing the crushing strength test results of coarse pseudo-particles produced by changing the addition ratio of ultrafine particles.
  • a granulation system B composed of a high speed stirring mixer and a pan pelletizer were used.
  • granulation was performed using only the granulation system A, followed by firing.
  • Comparative Examples 2 and 3 and the present invention example the predetermined sintering raw materials shown in Table 3 were charged into the granulation systems A and B, respectively, and granulated water and in the present invention example iron ore. After the slurry was added and granulated, the sintered raw materials granulated by the granulation systems A and B were merged and fired.
  • Iron ore slurry is one of the brands of pisolite ore. A was obtained by wet grinding with a tower mill. Further, in the present invention example, the weight ratio of iron ore to water in the total weight of iron ore slurry is about 50:50, and the ratio of ultrafine particles of 10 ⁇ m or less in the iron ore is 50% by mass. It used for the test.
  • the amount of iron ore to be supplied is increased or the amount of water to be supplied together with iron ore is reduced to thereby reduce the iron ore in the slurry. It is possible to increase the concentration of stone particles. However, an increase in the concentration of iron ore particles leads to inhibition of movement of the iron ore particles in water during the crushing process, resulting in a decrease in grinding efficiency. Therefore, in order to perform efficient pulverization, it is necessary to adjust the particle concentration in the slurry to 25% by volume or less, more preferably 20% by volume or less.
  • the preferred concentration of iron ore particles in the iron ore slurry is preferably 15% by volume or more and 25% by volume or less.
  • the density of iron ore is about 4 g / cm 3 for relatively porous pisolite ore and maramamba ore, and about 5 g / cm 3 for relatively dense hematite ore.
  • a concentration range of about 41% by mass or more and about 63% by mass or less is a preferable concentration range.
  • the iron ore slurry in the above-described example of the present invention has a SF. Density of about 4 g / cm 3 . Since A was used, the weight ratio of iron ore to water was about 50:50 when pulverized so that the concentration of iron ore particles in the slurry was 20% by volume. Moreover, since the ratio of the ultrafine particles of 10 ⁇ m or less in the iron ore particles in the iron ore slurry has an upper limit on the moisture that can be added during granulation as described above, it is desirable that the ratio be as high as possible.
  • the ratio of the ultrafine particles in the iron ore particles in the slurry is increased, the amount of circulating fine particles without being discharged from the pulverizer until the predetermined particle size is reached increases, so that the pulverization efficiency and the pulverization amount are reduced.
  • an iron ore slurry in which the ratio of ultrafine particles of 10 ⁇ m or less to the iron ore particles is 50% by mass is used in view of the balance between them.
  • the capacity of the pulverizer is sufficiently high, it seems that it is relatively easy to increase the ratio of ultrafine particles while maintaining the pulverization amount.
  • the iron ore slurry having a low pulverizer capacity and a low ratio of ultrafine particles can be supplied, it can be said that there is no problem if it is possible to add a predetermined amount of ultrafine particles according to the amount of pellet feed.
  • the pseudo-particles of Conventional Examples 1-2, Comparative Examples 1-3, and Example of the Invention produced as described above were placed in a sintering test pot having an inner diameter of 300 mm, a raw material layer thickness of 500 mm, and a weight of about 60 kg. Then, a pot sintering test was conducted. At that time, after igniting with an LPG burner for 1 minute while sucking under a pan pressure of 20 kPa, firing was performed with the pan bottom pressure constant at 9.8 kPa, and suction was performed 3 minutes after the exhaust gas temperature reached the maximum temperature. Stopped, thereby forming a sintered cake and completing the firing. After completion of the sintering test, the sinter production rate was obtained and evaluated by the following method.
  • the sintered cake was immediately removed from the sintering test pan and allowed to cool until the temperature of the sintered cake dropped to room temperature. After the cooling was completed, the produced sintered cake was dropped from a height of 2 m four times, and the sieve mesh was sieved with a 5 mm sieve to measure the mass on the sieve to obtain the sintered ore production rate.
  • the sintered ore production rate means a value obtained by dividing the mass on the sieve after sieving with a 5 mm sieve by the effective area of the sintering machine and the sintering time. Calculated. At this time, in the case of the pot sintering test, the cross-sectional area of the sintering test pot was used as the effective area of the sintering machine.
  • Sinter production rate (ton / m 2 / day) [mass of sintered ore with a particle size of 5 mm or more (ton) / ⁇ effective area of the sintering machine (m 2 ) ⁇ sintering time (min) ⁇ ] ⁇ 60 ⁇ 24 (1)
  • FIG. 6 is a diagram showing the evaluation result of the production rate of sintered ore by the pot sintering test.
  • the sinter production rate in the case of the conventional example 1 is set as the reference value (100), and the case of the conventional example 2, the comparative examples 1 to 3 and the present invention example with respect to this reference value.
  • the sinter production efficiency is shown as a relative value.
  • Comparative Example 1 In Comparative Example 1, the blending ratio of high-grade fine iron ore (pellet feed (PF.A)) is set to three conditions of 5.00, 10.00, and 20.00 mass%, and all sintered raw materials are granulated system A. When granulating, 3.00% by mass of quick lime was added as a binder. Thereafter, it was charged into a sintering machine and fired. As shown in FIG. 6, in the case of Comparative Example 1, the relative production rate was increased as a whole by the addition of quicklime, but when 20.00% by mass of pellet feed was blended, quicklime was very 3.00% by mass. The relative production rate did not reach 100 even though a large amount was added.
  • pellet feed PF.A
  • Comparative Example 2 high-quality fine iron ore (pellet feed (PF.A)) was blended in a total of 13.20% by mass and granulated. That is, granulation system B granulates 20.00% by mass of the total sintered raw material containing 9.35% by mass of pellet feed, and granulation system A holds the remaining 80% of the total sintered raw material containing 3.85% by mass of pellet feed. 0.000 mass% was granulated. At that time, 1.80% by mass of quicklime was added in total. Thereafter, both the granulation system A and the granulation system B were mixed, charged into a sintering machine, and fired. As shown in FIG. 6, from the result of Comparative Example 2, it was confirmed that the relative production rate was maintained equal to that of Conventional Example 1 until 13.20 mass% of the pellet feed was blended.
  • PF.A pellet feed
  • Comparative Example 3 high-quality fine iron ore (pellet feed (PF.A)) was blended in a total amount of 20.00% by mass and granulated. That is, granulation system B granulates 20.00% by mass of the total sintered raw material containing 9.35% by mass of pellet feed, and granulation system A has the remaining 80% of the total sintered raw material containing 10.65% by mass of pellet feed. 0.000 mass% was granulated. At that time, 1.80% by mass of quicklime was added in total. Thereafter, both the granulation system A and the granulation system B were mixed, charged into a sintering machine, and fired. As shown in FIG. 6, from the result of Comparative Example 3, when the pellet feed was blended up to 20.00% by mass, the granulation system B was used in combination and quick lime was added in a total of 1.80% by mass. It was confirmed that the relative production rate reached only about 84%.
  • granulation system B granulates 20.00% by mass of the total sintering raw material including 14.00% by mass of pellet feed (70% by mass in the sintering raw material of granulation system B). The remaining 80.00% by mass of the total sintered raw material containing 6.00% by mass of pellet feed was granulated. At that time, 1.80% by mass of quicklime was added in total. Furthermore, iron ore slurry was added in the granulation system B.
  • the iron ore slurry was added to a part of the sintering raw material that contained 50% by mass or more of fine iron ore. At this time, the iron ore slurry was added such that the weight of the iron ore excluding moisture in the iron ore slurry was 0.40% by mass with respect to the total sintered raw material. As described above, since the ratio of the ultrafine particles in the iron ore in the iron ore slurry is 50% by mass, the ultrafine particles of 10 ⁇ m or less per 0.01% by mass of the pellet feed in the blended sintered raw material are 0.01% by mass. % Is added. As shown in FIG. 6, in the case of the example of the present invention, the relative production rate could be maintained equal to that of the conventional example 1 even when the pellet feed was mixed at 20.00% by mass by adding the iron ore slurry.
  • the relative feed rate decreased in the case of Comparative Examples 1 to 3, and the pellet feed was reduced to 1.0% by mass even in the range where the blending rate of the pellet feed was higher than 13.20% by mass.
  • the iron ore slurry so that the ultrafine particles in the iron ore slurry become 0.01% by mass or more, the production rate of sintered ore is maintained even if the pellet feed is blended up to 20.00% by mass. I knew it was possible.
  • a new raw material-based blending ratio in which the amount of so-called new raw material is expressed as 100% by mass, in which the return ore is expressed in the same manner as the carbonaceous material, is often used.
  • the blending rate based on the new raw material it can be said that the production rate is maintained even if the pellet feed is blended up to 25% by mass according to the present invention.
  • the granulation method of the sintered raw material of the present invention is classified by the action of gravity and centrifugal force, as described above, and a pulverizing part composed of a cylindrical container provided with screw blades on the vertical center shaft to be rotationally driven.
  • Iron ore is wet pulverized using a vertical pulverizer having a classification part and a circulation part that circulates the underflow classified in the classification part to the cylindrical container of the pulverization part, and the iron ore slurry formed by wet pulverization is obtained. It is characterized by adding to all or part of the sintering raw material and granulating.
  • the sintering raw material has a ratio of particle size of 250 ⁇ m or less of 80% by mass or more and T.I.
  • a specific brand of fine iron ore containing 60% by mass or more of Fe (total iron) eg, pellet feed
  • the amount of ultrafine particles having a particle size of 10 ⁇ m or less among the iron ore in the iron ore slurry is 0% relative to 1.0% by mass of the fine iron ore. It is preferable to granulate by adding the iron ore slurry so as to be 0.01 mass% or more.
  • the sintering raw material is composed of raw materials such as iron ore containing a large amount of pellet feed as a high-quality fine iron ore, auxiliary raw material, return ore, carbonaceous material, etc., and granulation system A, granulation system B, and crushing Divided into three systems.
  • the raw material of the granulation system A is granulated by a granulator composed of a drum mixer into pseudo particles.
  • the raw material of the granulation system B is mixed and humidity-controlled by a high-speed stirring mixer, and then granulated by a pan pelletizer into coarse pseudo particles.
  • the raw material of the crushing system is preliminarily pulverized and mixed with water by wet pulverization using a tower mill, which is a vertical pulverizer, to obtain iron ore slurry.
  • the iron ore slurry produced in the crushing system is added to the high-speed stirring mixer together with the raw material of the granulation system B in the granulation of the granulation system B, and becomes a binder when the raw material of the granulation system B is granulated.
  • Pseudoparticles produced by granulation of each granulation system are mixed in the process of being charged into the surge hopper, further cut out by the roll feeder, and dropped and deposited on the pallet of the sintering machine. It is mixed in the process of forming the binder filling layer.
  • the sintered raw material packed layer thus formed is ignited on the upper surface in an ignition furnace, and while moving from the supply section to the discharge section, air suction from below causes the upper to lower portion of the packed bed. Are fired sequentially.
  • the sintered cake after firing is discharged from the discharge portion of the sintering machine, crushed by a crusher, cooled by a cooler, sized by a sieve, and conveyed to a blast furnace.
  • wet pulverization is adopted as a technique for producing an iron ore slurry to be added to a sintering raw material, for the following reason.
  • the ultrafine particles are required to be well mixed with the added water because of the mechanism of manifestation of the binder effect of the ultrafine particles.
  • wet pulverization is an excellent technique that satisfies the requirements because it can pulverize iron ore and suspend the pulverized ultrafine particles in water without using a dispersant or the like.
  • a tower mill which is a vertical pulverizer is used for wet pulverization.
  • the tower mill can apply a large pulverization force by a composite stirring in the circumferential direction and the vertical direction, and can produce extremely fine particles having a shape with many irregularities that are excellent in binder properties. It is.
  • the present invention is extremely useful as a technique that can cope with the depletion of high-grade fine iron ore.

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Abstract

This method for granulation of sintering raw material includes wet pulverization of iron ore using a vertical pulverizer having a pulverization unit formed from a cylindrical vessel provided with screw blades on a vertical central shaft that is driven rotatably, a sorting unit that sorts by the action of gravity and centrifugal force, and a circulation unit that circulates the underflow that has been sorted by the sorting unit to the cylindrical vessel of the pulverization unit, and granulation after adding an iron ore slurry from this wet pulverization to all or part of a sintering raw material. By using the sintering raw material granulated by this method, high quality fine powdered iron ore of a specific brand such as Pellet Feed can be mixed in with large amounts, and even when the proportion of fine powder in the sintering raw material is increased, air permeability of the filling layer can be assured and productivity for sintered ore can be maintained inexpensively.

Description

焼結原料の造粒方法Granulation method of sintering raw material
　本発明は、高炉で使用される焼結鉱を製造する際の焼結原料の造粒方法に関し、特に、焼結原料として難造粒性の微粉鉄鉱石の配合比率を増加させる場合でも、焼結鉱の生産性を安価に維持することができる焼結原料の造粒方法に関する。 The present invention relates to a method for granulating a sintered raw material when producing a sintered ore used in a blast furnace, and in particular, even when increasing the blending ratio of hardly granulated fine iron ore as a sintering raw material. The present invention relates to a method for granulating a sintered raw material capable of maintaining the productivity of the ore at low cost.
　一般に、高炉で鉄源として使用される焼結鉱は、次のようにして製造される。種々の銘柄の鉄鉱石と、石灰石などの副原料と、粉コークスなどの炭材と、返鉱（焼結された原料である焼結ケーキを破砕し、篩にかけて、篩下として得られる粒子）を予め定められた比率で配合して焼結原料とし、この焼結原料に水分を添加し、混合、調湿および造粒処理を施す。これにより、焼結原料は、３～５ｍｍ程度の比較的大きな粒子を核とし、この核粒子の周囲を、核粒子よりも細かくて「付着粉」と呼ばれる１ｍｍ以下の粒子が取り巻いた、擬似的な粒子（以下、「擬似粒子」とも言う）に造粒される。 Generally, sintered ore used as an iron source in a blast furnace is manufactured as follows. Various brands of iron ore, auxiliaries such as limestone, charcoal such as powdered coke, and return (particles obtained by crushing the sintered cake, which is a sintered raw material, and passing it through a sieve) Are mixed at a predetermined ratio to obtain a sintering raw material, and moisture is added to the sintering raw material, followed by mixing, humidity conditioning and granulation treatment. As a result, the sintered raw material has a relatively large particle of about 3 to 5 mm as a core, and the core particle is finer than the core particle and surrounded by particles of 1 mm or less called “adhering powder”. Granulated into small particles (hereinafter also referred to as “pseudoparticles”).
　造粒された焼結原料は、焼結機のパレット上に装入され、パレット上で焼結原料充填層（以下、単に「充填層」とも言う）を形成する。充填層は、焼結機の点火炉でその上部表面に着火され、これにより、充填層内に存在する炭材の燃焼が開始し、炭材の燃焼部分は燃焼帯を形成する。燃焼帯は、充填層が下方から吸引されているため、充填層の上部から下部に向かって次第に移行する。燃焼帯では、燃焼熱によって周囲の擬似粒子が昇温されて部分的に溶融し、その融液により擬似粒子間が架橋されて焼結する。これにより、充填層は最終的に焼結ケーキとなる。焼結ケーキは、焼結機から排鉱され、クラッシャーにより破砕され、篩で整粒され、篩上が焼結鉱となり、篩下は返鉱として焼結原料に戻される。 The granulated sintered raw material is charged on a pallet of a sintering machine to form a sintered raw material packed layer (hereinafter also simply referred to as “filled layer”) on the pallet. The packed bed is ignited on the upper surface thereof in an ignition furnace of the sintering machine, whereby the combustion of the carbonaceous material existing in the packed bed starts, and the combustion portion of the carbonized material forms a combustion zone. Since the packed bed is sucked from below, the combustion zone gradually moves from the upper part to the lower part of the packed bed. In the combustion zone, the surrounding pseudo particles are heated by the combustion heat and partially melted, and the pseudo particles are crosslinked and sintered by the melt. Thereby, the packed bed finally becomes a sintered cake. The sintered cake is discharged from the sintering machine, crushed by a crusher, sized with a sieve, the sieve top becomes sintered ore, and the sieve below is returned to the sintered raw material as return ore.
　ところで、焼結鉱の鉄品位は高炉の操業成績に深く係わり、さらに、環境保全の観点から高炉で排出されるＣＯ2量の削減が強く求められる状況からして、高品位な焼結鉱を製造することは重要である。しかし、近年、焼結原料としての高品位な粉鉄鉱石は枯渇してきている。このような状況から、焼結鉱の鉄品位を維持するためには、高品位な粉鉄鉱石の代わりに高品位な微粉鉄鉱石を多量に使用するのが今後の焼結鉱の製造形態であると予想される。 By the way, the iron grade of sintered ore is deeply related to the operating results of the blast furnace, and further, from the viewpoint of environmental protection, it is strongly required to reduce the amount of CO 2 emitted from the blast furnace. It is important to manufacture. However, in recent years, high-quality fine iron ore as a sintering raw material has been depleted. Under these circumstances, in order to maintain the iron grade of sintered ore, the production form of sintered ore is to use a large amount of fine grade iron ore instead of high grade fine iron ore. Expected to be.
　ここでいう高品位な微粉鉄鉱石とは、ＪＩＳ(Japanese Industrial Standards)　Ｍ　８７１６に規定される鉄鉱石の粒度分布測定法に基づき、篩目が２５０μｍの篩で篩ったときの篩下（粒子径が２５０μｍ以下）の比率が８０質量％以上であって、Ｔ．Ｆｅ（全鉄）が６０質量％以上である鉄鉱石のことを指す。具体的な例としては選鉱処理により鉄品位を向上させたペレットフィード鉄鉱石が挙げられる。このような高品位な微粉鉄鉱石は、以下では、単に、「ペレットフィード」ともいう。 The high-grade fine iron ore mentioned here is based on the particle size distribution measurement method of iron ore specified in JIS (Japanese Industrial Standards) M 8716. The ratio of the diameter is 250 μm or less) is 80% by mass or more, It refers to iron ore with Fe (total iron) of 60% by mass or more. As a specific example, pellet feed iron ore whose iron grade has been improved by a beneficiation treatment can be mentioned. Such high-quality fine iron ore is also simply referred to as “pellet feed” below.
　しかし、焼結鉱の製造において、ペレットフィードの使用量を単純に多くすると、焼結原料の微粉比率が増加し、擬似粒子を焼結機のパレットに装入する際に充填層に形成される空隙が、造粒されることなくそのまま残存した微粉で閉塞されるので、充填層の通気性が阻害される。その結果、燃焼帯が上部から下部に向かって移行する速度である焼成速度が低下し、焼結鉱の生産性が悪化する。 However, if the amount of pellet feed used is simply increased in the production of sintered ore, the fine powder ratio of the sintering raw material increases, and it is formed in the packed bed when the pseudo particles are charged into the pallet of the sintering machine. Since the voids are blocked by the fine powder remaining without being granulated, the air permeability of the packed bed is hindered. As a result, the firing rate, which is the rate at which the combustion zone moves from the upper part toward the lower part, decreases, and the productivity of the sintered ore deteriorates.
　従来、焼結原料における微粉比率の増加に伴う生産性の悪化に対しては、例えば下記の非特許文献１に記述されるように、生石灰の添加で対応している。しかし、同文献に記述される通り、生石灰による付着粉の着粉率向上効果は、生石灰の配合率が２質量％までは顕著であるが、それを超えて配合しても殆ど変化しない。また、生石灰は、工業的に石灰石を９００℃以上に加熱することで生産されるため、製造に高エネルギーを必要とし、コストが高い。そのため、生石灰の使用量はできる限り抑制するのが望ましい。 Conventionally, the deterioration of productivity accompanying the increase in the fine powder ratio in the sintered raw material is dealt with by adding quick lime as described in Non-Patent Document 1 below, for example. However, as described in the same document, the effect of improving the rate of adhesion of adhering powder due to quick lime is remarkable up to a blending ratio of quick lime of up to 2% by mass, but hardly changes even if blended beyond that. In addition, quick lime is produced by industrially heating limestone to 900 ° C. or higher, and therefore requires high energy for production and high cost. Therefore, it is desirable to suppress the amount of quicklime used as much as possible.
　そこで、焼結原料における微粉比率の増加に対応し、生石灰によらない、または生石灰の使用量を抑制する技術の開発が行われている。その具体的な技術は、例えば下記の特許文献１～５に提案されている。 Therefore, in response to the increase in the fine powder ratio in the sintered raw material, development of a technology that does not rely on quick lime or suppresses the use of quick lime is being carried out. Specific techniques thereof are proposed in, for example, the following Patent Documents 1 to 5.
　特許文献１には、造粒性の劣る鉄系原料として集塵ダスト、砂鉄、マラマンバ鉱石、およびペレットフィードのうちの少なくとも一種を全焼結原料中に３０質量％以上配合し、その鉄系原料に界面活性剤を含有する水分を添加して、他の焼結原料と共に造粒する焼結鉱の製造方法が記載されている。この方法によれば、上記した造粒性の劣る鉄系原料粒子の濡れ性が改善され、その結果として、焼結鉱の造粒および生産性が改善されるとしている。 In Patent Document 1, at least one of dust collection dust, iron sand, maramamba ore, and pellet feed as an iron-based raw material with poor granulation property is blended in a total sintered raw material by 30% by mass or more, and the iron-based raw material is included. A method for producing sintered ore is described in which moisture containing a surfactant is added and granulated together with other sintering raw materials. According to this method, the wettability of the iron-based raw material particles having the poor granulation property is improved, and as a result, the granulation and productivity of the sintered ore are improved.
　しかし、界面活性剤は上記の生石灰と同様に高価であり、ペレットフィードを多量に配合した場合、界面活性剤の使用量も必然的に多くなる。このため、特許文献１に記載された方法では、ペレットフィードの多量配合による微粉比率の増加への対応を安価に達成することは困難である。 However, the surfactant is expensive like the above-mentioned quicklime, and when a large amount of pellet feed is blended, the amount of the surfactant used is inevitably increased. For this reason, with the method described in Patent Document 1, it is difficult to achieve a low cost response to an increase in the fine powder ratio due to a large amount of pellet feed.
　特許文献２には、生石灰を湿式粉砕して製造した消石灰スラリーを、造粒機内の焼結原料に噴霧して添加する焼結原料の造粒方法が記載されている。この方法によれば、生石灰を乾式粉砕して添加するよりも焼結鉱の生産性が向上するとしている。 Patent Document 2 describes a method of granulating a sintered raw material in which a slaked lime slurry produced by wet pulverizing quick lime is sprayed onto a sintered raw material in a granulator and added. According to this method, the productivity of sintered ore is improved as compared with adding dry lime after dry grinding.
　しかし、消石灰スラリーの原料は生石灰であるため、特許文献２に記載された方法でペレットフィードを多量に配合した場合、消石灰スラリー、ひいては生石灰の使用量も必然的に多くなり、コストの悪化は避けられない。 However, since the raw material of the slaked lime slurry is quick lime, when a large amount of pellet feed is blended by the method described in Patent Document 2, the amount of slaked lime slurry and thus quick lime is inevitably increased, avoiding cost deterioration. I can't.
　特許文献３には、焼結原料の一部を予め造粒する選択造粒工程において、ポリアクリル酸などの高分子化合物、および炭酸カルシウムなどの平均粒径が２００μｍ以下の微粒子のうちの少なくとも一方を添加して、難造粒性のマラマンバ鉱石やペレットフィードなどを造粒し、その後に、残りの焼結原料と混合する焼結原料の造粒方法が記載されている。 In Patent Document 3, in a selective granulation step in which a part of a sintering raw material is granulated in advance, at least one of a polymer compound such as polyacrylic acid and fine particles having an average particle diameter of 200 μm or less such as calcium carbonate is disclosed. Is added, and a granulated method of a sintered raw material in which hardly granulated maramamba ore or pellet feed is granulated and then mixed with the remaining sintered raw material is described.
　しかし、高分子化合物や炭酸カルシウムは上記の生石灰と同様に高価であり、特許文献３に記載された方法でペレットフィードを多量に配合した場合、コストの悪化は避けられない。 However, polymer compounds and calcium carbonate are expensive like the above-mentioned quick lime, and when a large amount of pellet feed is blended by the method described in Patent Document 3, cost deterioration is inevitable.
　特許文献４には、焼結原料粒子に、バインダーとして平均粒径が１０μｍ以下の鉄鉱石超微粉を２～１５質量％の範囲内で添加混合し、その原料粒子を成形する方法が記載されている。この方法では、平均粒径が１０μｍ以下の鉄鉱石超微粉として、単に鉄鉱石の山元において発生する選鉱残渣である尾鉱を用いるとしている。 Patent Document 4 describes a method of forming raw material particles by adding and mixing iron ore ultrafine powder having an average particle size of 10 μm or less as a binder within a range of 2 to 15% by mass to sintered raw material particles. Yes. In this method, tailings, which are beneficiation residues generated at the base of iron ore, are used as the ultrafine iron ore powder having an average particle size of 10 μm or less.
　しかし、尾鉱は山元で発生するものであるため、バインダーとして必要な量を如何に安定して供給できるか不明である。また、尾鉱の他に鉄鉱石超微粉を得る具体的な方法も不明である。これらのことから、特許文献４に記載された方法は実現性に乏しい。 However, since tailings are generated at the base of the mountain, it is unclear how stably the necessary amount of binder can be supplied. In addition to the tailings, the specific method for obtaining ultrafine iron ore is also unknown. For these reasons, the method described in Patent Document 4 has poor feasibility.
　特許文献５には、鉄鉱石を含む焼結原料をローラープレス破砕機で圧縮破砕した後、ポリアクリル酸系の分散剤を添加して造粒する焼結原料の造粒方法が記載されている。この方法では、焼結原料をローラープレス破砕機で処理することにより、バインダーである粒度４５μｍ以下の超微粒子を大量に得ることができ、造粒時に擬似粒子化を効率良く行えるとともに、造粒物の強度が向上するとしている。 Patent Document 5 describes a method for granulating a sintered raw material in which a sintered raw material containing iron ore is compressed and crushed by a roller press crusher and then granulated by adding a polyacrylic acid-based dispersant. . In this method, by processing the sintered raw material with a roller press crusher, a large amount of ultrafine particles having a particle size of 45 μm or less as a binder can be obtained, and pseudo-particles can be efficiently formed at the time of granulation, and the granulated product It is said that the strength of will improve.
　しかし、特許文献５に記載された方法では、ローラープレス破砕機で乾式粉砕した超微粒子を、ポリアクリル酸系の分散剤を添加することで水中に分散させており、分散剤の使用によるコスト悪化が避けられず、更なる改善の余地がある。 However, in the method described in Patent Document 5, ultra fine particles dry-pulverized by a roller press crusher are dispersed in water by adding a polyacrylic acid-based dispersant, and the cost is deteriorated due to the use of the dispersant. However, there is room for further improvement.
特開２００４－１８３０３１号公報JP 2004-183031 A 特開昭６２－５６５３３号公報JP-A 62-56533 特開２００５－０９７６８６号公報Japanese Patent Laid-Open No. 2005-097686 特開２００９－１４４２４０号公報JP 2009-144240 A 特開２００７－１６２１２７号公報JP 2007-162127 A
　本発明は、上記の問題に鑑みてなされたものであり、ペレットフィードといった特定銘柄の高品位な微粉鉄鉱石を多量に配合し、焼結原料の微粉比率が増加する場合であっても、充填層の通気性を確保でき、焼結鉱の生産性を安価に維持することができる焼結原料の造粒方法を提供することを目的とする。 The present invention has been made in view of the above-mentioned problems, and a large amount of high-grade fine iron ore of a specific brand such as pellet feed is blended, even if the fine powder ratio of the sintering raw material is increased, An object of the present invention is to provide a method for granulating a sintered raw material that can ensure the air permeability of the layer and can maintain the productivity of the sintered ore at low cost.
　上記の目的を達成するため、本発明の焼結原料の造粒方法は、鉄鉱石、炭材、副原料および返鉱を配合して焼結原料とし、当該焼結原料を混合、調湿および造粒処理するに際して、回転駆動する鉛直中心軸にスクリュー翼を備えた円筒容器からなる粉砕部と、重力および遠心力の作用により分級する分級部と、分級部で分級したアンダーフローを粉砕部の円筒容器に循環させる循環部と、を有する竪型粉砕機を用いて鉄鉱石を湿式粉砕し、この湿式粉砕してなる鉄鉱石スラリーを焼結原料の全部または一部に添加して造粒することを特徴とする。 In order to achieve the above object, the method for granulating a sintered raw material according to the present invention comprises mixing iron ore, carbonaceous material, auxiliary raw material and return mineral to obtain a sintered raw material, mixing the sintered raw material, adjusting the humidity and In the granulation process, the pulverizing unit is composed of a pulverizing unit composed of a cylindrical container having screw blades on a rotating vertical center axis, a classifying unit classified by the action of gravity and centrifugal force, and an underflow classified by the classifying unit. An iron ore is wet pulverized using a vertical pulverizer having a circulation part that circulates in a cylindrical container, and the iron ore slurry formed by wet pulverization is added to all or part of the sintering raw material and granulated. It is characterized by that.
　この造粒方法において、前記焼結原料は、粒子径２５０μｍ以下の比率が８０質量％以上であってＴ．Ｆｅ（全鉄）を６０質量％以上含有する特定銘柄の微粉鉄鉱石を、少なくとも全焼結原料中に１３．２０質量％よりも高く２０．００質量％以下で含有しており、この焼結原料の全部、またはこの焼結原料の一部であって当該微粉鉄鉱石を５０質量％以上含む部分に、前記鉄鉱石スラリー中の鉄鉱石のうちで粒子径が１０μｍ以下である極微粒子の量が、前記微粉鉄鉱石１．０質量％に対して０．０１質量％以上となるように、前記鉄鉱石スラリーを添加して造粒することが好ましい。 In this granulation method, the sintering raw material has a ratio of particle size of 250 μm or less of 80% by mass or more, and T.I. A specific brand of fine iron ore containing 60% by mass or more of Fe (total iron) is contained in at least the total sintered raw material in an amount higher than 13.20% by mass and lower than 20.00% by mass. Or a portion of this sintering raw material that contains 50% by mass or more of the fine iron ore contains an amount of ultrafine particles having a particle size of 10 μm or less among the iron ores in the iron ore slurry. It is preferable to granulate by adding the iron ore slurry so as to be 0.01% by mass or more with respect to 1.0% by mass of the fine iron ore.
　ここでいう特定銘柄の微粉鉄鉱石は、例えば、高品位な南米産のペレットフィードが該当する。 Specified brand fine iron ore here is, for example, high-quality South American pellet feed.
　本発明の焼結原料の造粒方法によれば、竪型粉砕機を用いて鉄鉱石を湿式粉砕し、これにより得られた１０μｍ以下の鉄鉱石の極微粒子が懸濁しているスラリーを、造粒のバインダーとして焼結原料に添加することで、高品質の微粉鉄鉱石としてペレットフィードを多量に配合しても焼結生産性を維持することができる。 According to the granulation method of the sintered raw material of the present invention, the iron ore is wet-ground using a vertical pulverizer, and the slurry in which the ultrafine particles of the iron ore of 10 μm or less obtained thereby are suspended is formed. By adding to a sintering raw material as a binder for grains, sintering productivity can be maintained even if a large amount of pellet feed is blended as high-quality fine iron ore.
図１は、ペレットフィードおよび粉鉄鉱石の粒度分布をそれぞれ示す図である。FIG. 1 is a graph showing the particle size distribution of pellet feed and fine iron ore. 図２は、粉砕機で粉砕された鉄鉱石の走査電子顕微鏡（ＳＥＭ）による観察写真である。FIG. 2 is an observation photograph of an iron ore crushed by a pulverizer using a scanning electron microscope (SEM). 図３は、本発明の焼結原料の造粒方法で鉄鉱石スラリーを製造するために用いるタワーミルの全体構成を示す模式図である。FIG. 3 is a schematic diagram showing an overall configuration of a tower mill used for producing an iron ore slurry by the method for granulating a sintering raw material of the present invention. 図４は、極微粒子の添加比率を変更して製造した粗大擬似粒子の圧壊強度試験結果を示す図である。FIG. 4 is a diagram showing the crushing strength test results of coarse pseudo-particles produced by changing the addition ratio of ultrafine particles. 図５は、本発明の実施例における造粒系統の構成を示す図である。FIG. 5 is a diagram showing the configuration of the granulation system in the embodiment of the present invention. 図６は、鍋焼結試験による焼結鉱の生産率の評価結果を示す図である。FIG. 6 is a diagram showing the evaluation results of the production rate of sintered ore by the pot sintering test.
　以下に、本発明の焼結原料の造粒方法について、本発明を完成するに至った経緯、および本発明の好ましい態様を説明する。 Hereinafter, the background of the present invention and the preferred embodiment of the present invention will be described with respect to the method for granulating the sintering raw material of the present invention.
　まず、本発明者らは、粒子径が１０μｍ以下の鉄鉱石の極微粒子（以下、単に「極微粒子」とも言う）が、造粒におけるバインダーとなるという知見に着目した。極微粒子が造粒においてバインダーとして働く詳細なメカニズムは、以下の通りである。 First, the present inventors paid attention to the knowledge that ultrafine particles of iron ore having a particle diameter of 10 μm or less (hereinafter also simply referred to as “ultrafine particles”) serve as a binder in granulation. The detailed mechanism in which ultrafine particles act as a binder in granulation is as follows.
　焼結原料の造粒では、３～５ｍｍ程度の比較的大きな粒子を核とし、この核粒子の周囲を、核粒子よりも細かくて付着粉と呼ばれる１ｍｍ以下の粒子が取り巻いて、擬似粒子を形成する。核粒子と付着粉とを結合するバインダーの役目を担うのは、添加された水分（以下、「添加水分」とも言う）であり、この添加水分は混合・攪拌・造粒の過程で核粒子と付着粉との間に入り込んで両者を結合する。 In the granulation of the sintering raw material, relatively large particles of about 3 to 5 mm are used as nuclei, and the particles around the core particles are finer than the core particles and are surrounded by particles of 1 mm or less, forming pseudo particles. To do. It is the added water (hereinafter also referred to as “added water”) that serves as a binder that binds the core particles to the adhering powder, and this added water is combined with the core particles during the mixing, stirring, and granulation processes. It enters between the adhering powders and combines them.
　一方、焼結原料に含まれる粒子径が１０μｍ以下の極微粒子は、添加水分中に懸濁した場合に水と共に自由に移動することができるので、添加水分と一緒に核粒子と付着粉との間に入り込む。こうして、極微粒子が核粒子と付着粉との間を埋めて架橋を形成するので、擬似粒子の強度が増加するのである。 On the other hand, ultrafine particles with a particle size of 10 μm or less contained in the sintering raw material can move freely with water when suspended in the added water, so the core particles and the adhering powder together with the added water. Get in between. In this way, the ultrafine particles fill the space between the core particles and the adhering powder to form a bridge, thereby increasing the strength of the pseudo particles.
　このメカニズムによる強度上昇は、核粒子と付着粉とからなる擬似粒子だけでなく、核粒子を含まずに全量が１ｍｍ以下の粒子からなる擬似粒子（以下、「Ｐ型擬似粒子」と言う）においても発現すると推察される。ただし、このようなＰ型擬似粒子の製造では、バインダーである極微粒子も大量に必要となること、Ｐ型擬似粒子が通常の擬似粒子と比べて焼結機のパレット上に装入した際の衝撃で崩壊しやすいことなどを鑑みると、核粒子と付着粉とからなる擬似粒子の造粒に極微粒子を添加するのがより望ましい。 The increase in strength due to this mechanism is not only in the pseudo particles composed of the core particles and the adhering powder, but also in the pseudo particles (hereinafter referred to as “P-type pseudo particles”) including the core particles and not including the core particles and having a total amount of 1 mm or less. Is also expected to develop. However, in the production of such P-type pseudo particles, a large amount of ultrafine particles as a binder is required, and when the P-type pseudo particles are charged on a pallet of a sintering machine as compared with normal pseudo particles. In view of the fact that it is easily disintegrated by impact, it is more desirable to add ultrafine particles to the granulation of pseudo particles composed of core particles and attached powder.
　ここで、本発明者らは、ペレットフィードの性状を調査したところ、ペレットフィードは、粒子径が２５０μｍ以下の粒子を８０質量％以上含む微粉原料である一方、１０μｍ以下の極微粒子をほとんど含んでいないことを突き止めた。ペレットフィードは、山元で選鉱処理、具体的には粉砕、磨鉱、水洗、浮選などの処理を行って鉄品位を向上させており、その過程で極微粒子が取り除かれているためである。 Here, the present inventors investigated the properties of the pellet feed, and the pellet feed is a fine powder raw material containing 80% by mass or more of particles having a particle size of 250 μm or less, and almost contains extremely fine particles of 10 μm or less. I have not found out. This is because the pellet feed improves the iron quality by performing a beneficiation process, specifically, grinding, polishing, washing, flotation, etc. at the mountain base, and ultrafine particles are removed in the process.
　従って、ペレットフィードの配合によって造粒性が悪化し得る。具体的には、擬似粒子を焼結機のパレット上に装入する際に充填層に形成される空隙が、造粒されることなくそのまま残存した微粉で閉塞され、充填層の通気性が阻害される。その原因は、ペレットフィードにはバインダーとなる極微粒子が不足するところが大きいことによる。 Therefore, granulation can be deteriorated by blending the pellet feed. Specifically, when the pseudo particles are placed on the pallet of the sintering machine, the voids formed in the packed bed are blocked by the fine powder remaining without being granulated, impairing the air permeability of the packed bed. Is done. This is due to the fact that the pellet feed is largely deficient in ultrafine particles serving as a binder.
　図１は、ペレットフィード（ＰＦ．Ａ）および粉鉄鉱石３銘柄（ＳＦ．Ａ、ＳＦ．Ｂ、ＳＦ．Ｃ）の粒度分布をそれぞれ示す図である。粒度分布は、粒子径が２５０μｍを超える粒子については、ＪＩＳ　Ｍ　８７１６に規定される鉄鉱石の湿式篩い分け法で測定し、粒子径が２５０μｍ以下の粒子については、湿式篩い分け法による測定で発生した２５０μｍ以下の粒子を含有する分別水を回収し、この分別水をＪＩＳ　Ｒ　１６２９で規定されるレーザー回折・散乱法で測定した。 FIG. 1 is a graph showing the particle size distribution of pellet feed (PF.A) and three types of fine iron ore (SF.A, SF.B, SF.C). The particle size distribution is measured by the wet sieving method of iron ore specified in JIS M 8716 for particles with a particle size exceeding 250 μm, and by the wet sieving method for particles having a particle size of 250 μm or less. The fractionated water containing particles of 250 μm or less was collected, and this fractionated water was measured by a laser diffraction / scattering method defined in JIS R 1629.
　図１に示すように、ＰＦ．Ａは、１０μｍより大きく２５０μｍ以下の粒子を８８．２％含んでいるが、１０μｍ以下の極微粒子は０．１％とほとんど含んでいない。一方、粉鉄鉱石はいずれも、１０μｍより大きく２５０μｍ以下の粒子の含有率は１０～２０％程度でＰＦ．Ａと比べて少ないにもかかわらず１０μｍ以下の極微粒子を１０～１５％程度含んでいる。 As shown in FIG. A contains 88.2% of particles larger than 10 μm and not larger than 250 μm, but contains very little 0.1% of ultrafine particles not larger than 10 μm. On the other hand, the powdered iron ore has a particle content of more than 10 μm and not more than 250 μm with a PF. Although it is smaller than A, it contains about 10 to 15% of ultrafine particles of 10 μm or less.
　また下記表１にＰＦ．Ａの成分を示す。Ｔ．Ｆｅを６０％以上含んでおり、高品位である。 In addition, PF. The component of A is shown. T.A. It contains 60% or more of Fe and has high quality.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　以上のことから、高品位の微粉鉄鉱石であるペレットフィードを多量に配合する場合であっても、１０μｍ以下の極微粒子を添加してバインダーとすることで、充填層の通気性を確保でき、焼結鉱の生産性を維持できるとの考えに至った。 From the above, even when blending a large amount of pellet feed, which is a high-grade fine iron ore, by adding ultrafine particles of 10 μm or less as a binder, the air permeability of the packed bed can be secured, It came to the idea that productivity of sintered ore can be maintained.
　また、上述した極微粒子のバインダー効果の発現メカニズムを鑑みるに、極微粒子は、添加水分と良く混ざり合っていることが重要であると言える。 Also, in view of the above-described mechanism of manifestation of the binder effect of the ultrafine particles, it can be said that it is important that the ultrafine particles are well mixed with the added water.
　前述したように、特許文献３では炭酸カルシウムなどを、特許文献４では尾鉱を、特許文献５ではローラープレスを用いて粉砕した鉄鉱石を、それぞれ極微粒子を含有するバインダーとして用いている。しかし、これらの方法による場合に、極微粒子をバインダーとして十分な効果を発揮させるには、例えば高分子の分散剤を添加するなどして、極微粒子を水中に良く分散させて懸濁させる工程が不可欠になると推察される。 As described above, Patent Document 3 uses calcium carbonate, Patent Document 4 uses tailings, and Patent Document 5 uses iron ore crushed using a roller press as binders containing ultrafine particles. However, in the case of using these methods, in order to exert a sufficient effect using the ultrafine particles as a binder, for example, a step of dispersing the ultrafine particles in water well and suspending them, for example, by adding a polymer dispersant. Inferred to be indispensable.
　そこで、本発明者らは、極微粒子の添加形態として、鉄鉱石の極微粒子を水中に懸濁させたスラリー（以下、「鉄鉱石スラリー」とも言う）を予め製造し、この鉄鉱石スラリーを焼結原料に添加する形態が安価にバインダー効果を得られる最良のものであると判断した。 Accordingly, the present inventors previously prepared a slurry in which ultrafine particles of iron ore are suspended in water (hereinafter also referred to as “iron ore slurry”) as an addition form of ultrafine particles, and the iron ore slurry is sintered. It was judged that the form to be added to the binding raw material is the best one that can obtain the binder effect at low cost.
　鉄鉱石スラリーの製造方法は、湿式粉砕が良い。これにより、鉄鉱石の粉砕と、粉砕した鉄鉱石の極微粒子の水中への懸濁を同時に行うことができ、分散剤を添加せずとも極微粒子と水とが良く混ざり合った状態となる。乾式粉砕の場合は、粉砕により得られた極微粒子をさらに水中に懸濁させるために混錬・捏和工程が別途必要となる。 The method for producing the iron ore slurry is preferably wet pulverization. Thereby, the pulverization of the iron ore and the suspension of the pulverized iron ore fine particles in water can be performed simultaneously, and the fine particles and water are well mixed without adding a dispersant. In the case of dry pulverization, a separate kneading / kneading step is required to further suspend the ultrafine particles obtained by pulverization in water.
　以上より、粉鉄鉱石を湿式粉砕により粉砕し、粉砕により得られた１０μｍ以下の鉄鉱石の極微粒子が懸濁しているスラリーを焼結原料に添加することにより、ペレットフィードを多量に配合し、焼結原料の微粉比率が増加する場合であっても、充填層の通気性を確保でき、焼結鉱の生産性を安価に維持することができることを見出した。 From the above, powder iron ore is pulverized by wet pulverization, and by adding a slurry in which ultrafine particles of iron ore of 10 μm or less obtained by pulverization are suspended to the sintering raw material, a large amount of pellet feed is blended, It has been found that even when the fine powder ratio of the sintered raw material increases, the air permeability of the packed bed can be secured and the productivity of the sintered ore can be maintained at a low cost.
　１．粉砕機で粉砕されてなる鉄鉱石粒子の性状
　図２は、粉砕機で粉砕された鉄鉱石の走査電子顕微鏡（ＳＥＭ）による観察写真である。同図（ａ）および（ｂ）は、前記特許文献５に記載されているボールミルによって粉砕した場合を、同図（ｃ）および（ｄ）は、同文献に記載されているローラープレスによって粉砕した場合を、それぞれ比較例として示している。同図（ｅ）および（ｆ）は、本発明例として、後述するタワーミルによって粉砕した場合を示している。それぞれの倍率は、図２（ａ）、（ｃ）および（ｅ）が５００倍であり、図２（ｂ）、（ｄ）および（ｆ）が３０００倍である。 1. 2. Properties of iron ore particles pulverized by a pulverizer FIG. 2 is an observation photograph of the iron ore pulverized by a pulverizer using a scanning electron microscope (SEM). (A) and (b) are the cases of pulverization by the ball mill described in Patent Document 5, and (c) and (d) are pulverized by the roller press described in the same document. Each case is shown as a comparative example. (E) and (f) of the same figure show the case where it grind | pulverizes with the tower mill mentioned later as an example of this invention. The respective magnifications are 500 times in FIGS. 2 (a), (c) and (e), and 3000 times in FIGS. 2 (b), (d) and (f).
　図３は、本発明の焼結原料の造粒方法で鉄鉱石スラリーを製造するために用いるタワーミルの全体構成を示す模式図である。同図に示すように、タワーミル１は、竪型の湿式粉砕機であり、大きくは、粉砕部と、分級部と、循環部とから構成される。粉砕部は、回転駆動する鉛直中心軸２に二重螺旋状のスクリュー翼３を備えた円筒容器４からなり、円筒容器４内には、粉砕媒体として鉄球が装入される。分級部は、円筒容器４の上部側面に接続された水簸槽５、および水簸槽５に接続されたサイクロン分級装置６からなる。循環部は、水簸槽５の下部から循環ポンプ７を経て円筒容器４の下部へ繋がる配管８、およびサイクロン分級装置６の下部から水簸槽５の上部に繋がる配管９からなる。 FIG. 3 is a schematic diagram showing the overall configuration of a tower mill used for producing an iron ore slurry by the method for granulating a sintering raw material of the present invention. As shown in the figure, the tower mill 1 is a vertical wet pulverizer, and is mainly composed of a pulverization unit, a classification unit, and a circulation unit. The pulverizing unit is composed of a cylindrical container 4 provided with a double spiral screw blade 3 on a vertical center shaft 2 that is rotationally driven. In the cylindrical container 4, an iron ball is charged as a pulverizing medium. The classification unit includes a water tank 5 connected to the upper side surface of the cylindrical container 4, and a cyclone classification device 6 connected to the water tank 5. The circulation section includes a pipe 8 connected from the lower part of the water tank 5 to the lower part of the cylindrical container 4 through the circulation pump 7 and a pipe 9 connected from the lower part of the cyclone classifier 6 to the upper part of the water tank 5.
　粉砕対象である鉄鉱石は、水と共に円筒容器４の上部から投入される。投入された鉄鉱石は円筒容器４の下部に落下し、円筒容器４内の鉄球と共に、鉛直中心軸２の回転駆動に伴うスクリュー翼３の回転によって円周方向に回転する運動、スクリュー翼３によって持ち上げられて上方に巻き上げられる運動、および自重によって下方に落下する運動を繰り返す。これらの複合的な運動により、鉄鉱石同士あるいは鉄鉱石と鉄球との間に剪断力や圧縮力が作用し、鉄鉱石が粉砕（破砕）される。 The iron ore to be crushed is thrown in from the upper part of the cylindrical container 4 together with water. The charged iron ore falls to the lower part of the cylindrical container 4, and moves together with the iron balls in the cylindrical container 4 in the circumferential direction by the rotation of the screw blades 3 accompanying the rotational drive of the vertical center shaft 2. The movement of being lifted up and wound upward and the movement of falling downward by its own weight are repeated. By these combined movements, a shearing force or a compressive force acts between the iron ores or between the iron ore and the iron ball, and the iron ore is crushed (crushed).
　円筒容器４内において、鉄鉱石は、粉砕が進行して粒度が次第に小さくなり、自重によって水中を落下する速度よりもスクリュー翼３の回転によって上方に巻き上げられる速度が大きくなると、円筒容器４内に満たされている水に懸濁してスラリー状になり、円筒容器４の上部側面の水簸槽５に流れ込む。 In the cylindrical container 4, the iron ore is gradually reduced in size as the pulverization progresses, and when the speed at which the iron ore is wound upward by the rotation of the screw blades 3 is larger than the speed at which the iron ore falls in water due to its own weight, It is suspended in filled water to form a slurry and flows into the water tank 5 on the upper side surface of the cylindrical container 4.
　水簸槽５に流れ込んだ鉄鉱石スラリーは、重力の作用によって粗分級される。このとき、分級された粗粒の鉄鉱石スラリーは、アンダーフロー（図３中の「Ｕ／Ｆ」参照）として水簸槽５の下部から配管８へ流れ込み、循環ポンプ７を経て円筒容器４の下部に戻されて再度粉砕される。一方、細粒の鉄鉱石スラリーは、オーバーフロー（図３中の「Ｏ／Ｆ」参照）としてサイクロン分級装置６へ流れ込む。 The iron ore slurry that has flowed into the water tank 5 is roughly classified by the action of gravity. At this time, the classified coarse iron ore slurry flows into the pipe 8 from the lower part of the water tank 5 as an underflow (see “U / F” in FIG. 3), passes through the circulation pump 7, and flows into the cylindrical container 4. It is returned to the lower part and pulverized again. On the other hand, the fine-grain iron ore slurry flows into the cyclone classifier 6 as an overflow (see “O / F” in FIG. 3).
　サイクロン分級装置６に流れ込んだ鉄鉱石スラリーは、遠心力の作用によってさらに細かく分級される。このとき、分級された粗粒の鉄鉱石スラリーは、アンダーフロー（図３中の「Ｕ／Ｆ」参照）として配管９を通じて水簸槽５の上部へ戻され、一方、細粒の鉄鉱石スラリーは、オーバーフロー（図３中の「Ｏ／Ｆ」参照）としてタワーミル１の系外に排出される。そして、系外に排出された鉄鉱石スラリーの分、新たに鉄鉱石と水が円筒容器４に投入される。また、粉砕媒体である鉄球は徐々に摩耗するため、適宜、鉄鉱石と共に円筒容器４に投入されて補充される。 The iron ore slurry that has flowed into the cyclone classifier 6 is further finely classified by the action of centrifugal force. At this time, the classified coarse iron ore slurry is returned to the upper part of the water tank 5 through the pipe 9 as an underflow (see “U / F” in FIG. 3), while the fine iron ore slurry Is discharged out of the tower mill 1 as an overflow (see “O / F” in FIG. 3). Then, iron ore and water are newly charged into the cylindrical container 4 by the amount of the iron ore slurry discharged out of the system. In addition, since the iron balls as the grinding media are gradually worn, they are appropriately put into the cylindrical container 4 together with the iron ore and replenished.
　以上のプロセスにより、タワーミル１は、造粒におけるバインダーとなる鉄鉱石の極微粒子を、水中に懸濁したスラリーとして連続的に供給することが可能である。ここで、水簸槽５とサイクロン分級装置６との間などの各装置間や、サイクロン分級装置６からのオーバーフローの出口には、投入量と排出量とのバランスをとるために、鉄鉱石スラリーを一時的に貯めておくスラリータンクを設置してもよい。 Through the above process, the tower mill 1 can continuously supply ultrafine particles of iron ore serving as a binder in granulation as a slurry suspended in water. Here, in order to balance the input amount and the discharge amount between each device such as between the water tank 5 and the cyclone classifier 6, and at the outlet of the overflow from the cyclone classifier 6, an iron ore slurry is used. A slurry tank for temporarily storing the above may be installed.
　前記図２（ａ）、（ｃ）、（ｅ）に示す観察写真を比較すると、タワーミルによって粉砕された鉄鉱石は、ボールミルおよびローラープレスによって粉砕された鉄鉱石と比べ、粒子径が顕著に小さいことが分かる。上述したように、タワーミルを用いた場合、鉄鉱石は、円周方向だけでなく垂直方向にも攪拌され粉砕される。そのため、例えばタワーミル以外の代表的な湿式粉砕機であるボールミルのように、容器の回転運動に伴う円周方向の攪拌のみで粉砕される場合と比較し、粒子同士の剪断力や圧縮力が強く作用する。その結果、タワーミルによって粉砕された鉄鉱石は、他の粉砕機による場合と比較して粒子径が顕著に小さくなると推察される。 Comparing the observation photographs shown in FIGS. 2 (a), 2 (c) and 2 (e), the iron ore crushed by the tower mill has a remarkably smaller particle size than the iron ore crushed by the ball mill and roller press. I understand that. As described above, when the tower mill is used, the iron ore is stirred and pulverized not only in the circumferential direction but also in the vertical direction. Therefore, the shearing force and compressive force between the particles are stronger compared to the case of pulverizing by only the circumferential stirring accompanying the rotational movement of the container, such as a ball mill which is a typical wet pulverizer other than the tower mill. Works. As a result, it is assumed that the iron ore crushed by the tower mill has a remarkably small particle size as compared with the case of using other pulverizers.
　また、核粒子と付着粉との間に入り込み架橋となるという極微粒子のバインダー効果の発現メカニズムを鑑みるに、極微粒子の形状は凹凸が多い方が核粒子と付着粉との間に入り込んだ際のバインダー効果が高いと推察される。この点、前記図２（ｂ）、（ｄ）、（ｆ）に示す観察写真を比較すると、タワーミルによって粉砕された鉄鉱石の表面は、ボールミルによって粉砕された鉄鉱石と比較して凹凸の多い形状をしている。 Also, considering the mechanism of the binder effect of the ultrafine particles that penetrates between the core particles and the adhering powder and forms a crosslink, the shape of the ultrafine particles is more uneven when entering between the core particles and the adhering powder. It is assumed that the binder effect is high. In this regard, when comparing the observation photographs shown in FIGS. 2B, 2D, and 2F, the surface of the iron ore crushed by the tower mill is more uneven than the iron ore crushed by the ball mill. It has a shape.
　以上より、タワーミルによって粉砕された鉄鉱石スラリーは、造粒における良好なバインダーとなる性状を有していることが観察された。 From the above, it was observed that the iron ore slurry pulverized by the tower mill has the property of becoming a good binder in granulation.
　２．造粒物の強度
　下記表２に示す通りの割合で、高品位の微粉鉄鉱石としてペレットフィード（ＰＦ．Ａ）を配合した焼結原料を４つ準備し、それぞれに対して比率の異なる極微粒子を添加して、直径約１０ｍｍ以上の粗大擬似粒子（以下、「グリーンボール」とも言う）を製造し、１０５℃で２時間以上乾燥した後に、各グリーンボールの圧壊応力を測定する圧壊強度試験を行った。その際、極微粒子は、ピソライト鉱石であるＳＦ．Ａを１０μｍ以下の極微粒子を６０質量％含有する状態となるまで粉砕し、添加した。 2. Strength of granulated material Four sintered raw materials prepared by blending pellet feed (PF.A) as high-grade fine iron ore in the proportions shown in Table 2 below are prepared. To produce coarse pseudo particles (hereinafter also referred to as “green balls”) having a diameter of about 10 mm or more, dried at 105 ° C. for 2 hours or more, and then a crushing strength test for measuring the crushing stress of each green ball. went. At that time, the ultrafine particles are SF. A was pulverized until it contained 60% by mass of ultrafine particles of 10 μm or less, and added.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
　図４は、極微粒子の添加比率を変更して製造した粗大擬似粒子の圧壊強度試験結果を示す図である。同図に示すように、焼結原料中の高品位の微粉鉄鉱石であるペレットフィード（ＰＦ．Ａ）４５．６０質量％に対し、極微粒子を０．６０質量％以上添加した場合、すなわち、同ペレットフィード１．０質量％に対し、極微粒子を約０．０１３質量％以上添加した場合、極微粒子を添加しないものと比較して、造粒物の強度上昇が確認された。これは、極微粒子の添加に伴ってバインダー効果が発現したものと推察される。 FIG. 4 is a diagram showing the crushing strength test results of coarse pseudo-particles produced by changing the addition ratio of ultrafine particles. As shown in the figure, when the fine particles are added in an amount of 0.60% by mass or more with respect to pellet feed (PF.A) 45.60% by mass, which is a high-quality fine iron ore in the sintering raw material, When about 0.013% by mass or more of ultrafine particles were added to 1.0% by mass of the pellet feed, an increase in strength of the granulated product was confirmed as compared with the case of adding no ultrafine particles. This is presumed that the binder effect was developed with the addition of ultrafine particles.
　３．鍋試験による焼結鉱生産率の評価
　下記表３に示す通りに、各種銘柄の鉄鉱石、副原料、返鉱、炭材などを所定の割合で配合し、配合した焼結原料を造粒設備内に装入するとともに、造粒水、および、本発明例では鉄鉱石スラリー（極微粒子スラリー）を添加して造粒し、擬似粒子を製造した。表３において、鉄鉱石スラリーは、表２と表記を合わせるために、炭材は、焼結の実機操業における慣用的な表記法に倣い、それぞれ配合率を外数で表記した。造粒には、図５に示すような、２機のドラムミキサーからなる造粒系統Ａ、および高速撹拌ミキサーとパンペレタイザーとからなる造粒系統Ｂを用いた。従来例１および２、ならびに比較例１では、造粒系統Ａのみを用いて造粒した後、焼成した。一方、比較例２および３、ならびに本発明例では、表３に示す所定の焼結原料を、造粒系統ＡおよびＢのそれぞれに装入し、造粒水、および、本発明例では鉄鉱石スラリーを、添加して造粒した後に、各造粒系統ＡおよびＢで造粒した焼結原料を、合流して、焼成した。 3. Evaluation of production rate of sintered ore by pot test As shown in Table 3 below, various brands of iron ore, auxiliary raw materials, return minerals, carbonaceous materials, etc. are blended at a predetermined ratio, and the blended sintered raw materials are granulated equipment. While charging, the granulated water and the iron ore slurry (ultrafine particle slurry) in the present invention example were added and granulated to produce pseudo particles. In Table 3, in order to match the notation of iron ore slurry with that in Table 2, the charcoal materials are in accordance with the conventional notation method in the actual operation of sintering, and the blending ratio is expressed as an external number. For granulation, a granulation system A composed of two drum mixers as shown in FIG. 5 and a granulation system B composed of a high speed stirring mixer and a pan pelletizer were used. In Conventional Examples 1 and 2 and Comparative Example 1, granulation was performed using only the granulation system A, followed by firing. On the other hand, in Comparative Examples 2 and 3, and the present invention example, the predetermined sintering raw materials shown in Table 3 were charged into the granulation systems A and B, respectively, and granulated water and in the present invention example iron ore. After the slurry was added and granulated, the sintered raw materials granulated by the granulation systems A and B were merged and fired.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　鉄鉱石スラリーは、ピソライト鉱石の銘柄の１つであるＳＦ．Ａをタワーミルによって湿式粉砕して得た。また、本発明例では、鉄鉱石スラリー全重量における鉄鉱石と水との重量比が約５０：５０であり、さらにその鉄鉱石中に占める１０μｍ以下の極微粒子の比率が５０質量％のものを試験に供した。 Iron ore slurry is one of the brands of pisolite ore. A was obtained by wet grinding with a tower mill. Further, in the present invention example, the weight ratio of iron ore to water in the total weight of iron ore slurry is about 50:50, and the ratio of ultrafine particles of 10 μm or less in the iron ore is 50% by mass. It used for the test.
　ここで、前記図３に示す竪型の湿式粉砕機（タワーミル）においては、供給する鉄鉱石の量を増加させたり鉄鉱石と共に供給する水の量を低下させたりすることで、スラリー中の鉄鉱石粒子の濃度を上昇させることが可能である。しかし、鉄鉱石粒子の濃度上昇は、破砕工程中における鉄鉱石粒子の水中での移動を阻害することにつながるので、粉砕効率の低下をもたらす。従って、効率的な粉砕を行うためには、スラリー中の粒子濃度は、２５体積％以下、より好適には２０体積％以下に調節する必要がある。 Here, in the vertical wet pulverizer (tower mill) shown in FIG. 3, the amount of iron ore to be supplied is increased or the amount of water to be supplied together with iron ore is reduced to thereby reduce the iron ore in the slurry. It is possible to increase the concentration of stone particles. However, an increase in the concentration of iron ore particles leads to inhibition of movement of the iron ore particles in water during the crushing process, resulting in a decrease in grinding efficiency. Therefore, in order to perform efficient pulverization, it is necessary to adjust the particle concentration in the slurry to 25% by volume or less, more preferably 20% by volume or less.
　一方、供給する鉄鉱石の量を低下させたり鉄鉱石と共に供給する水の量を増加させたりすることで、スラリー中の鉄鉱石粒子の濃度を低下させることも可能である。しかし、鉄鉱石粒子の濃度低下も、破砕中に鉄鉱石同士あるいは鉄鉱石と粉砕媒体（鉄球）との衝突回数の低下を引き起こし、粉砕効率の低下をもたらす。従って、効率的な粉砕を行うためには、スラリー中の粒子濃度は、１５体積％以上に調節する必要がある。ただし、造粒時に添加することができる水分には上限があり、限界以上の水分を添加して造粒すると原料の表面全体に水分が存在するようになって擬似粒子の強度が保てなくなる。この点を鑑みると、スラリー中の鉄鉱石粒子の濃度はできるだけ高いほうが望ましい。 On the other hand, it is possible to reduce the concentration of iron ore particles in the slurry by reducing the amount of iron ore to be supplied or increasing the amount of water supplied together with the iron ore. However, a decrease in the concentration of iron ore particles also causes a decrease in the number of collisions between iron ores or between the iron ore and the grinding medium (iron balls) during crushing, resulting in a reduction in grinding efficiency. Therefore, in order to perform efficient pulverization, it is necessary to adjust the particle concentration in the slurry to 15% by volume or more. However, there is an upper limit to the moisture that can be added at the time of granulation. If granulation is performed by adding more moisture than the limit, moisture is present on the entire surface of the raw material, and the strength of the pseudo particles cannot be maintained. In view of this point, it is desirable that the concentration of iron ore particles in the slurry be as high as possible.
　以上のことから、鉄鉱石スラリー中の鉄鉱石粒子の好適な濃度は、１５体積％以上、２５体積％以下であることが好ましい。ここで、鉄鉱石の密度は、比較的多孔質なピソライト鉱石やマラマンバ鉱石で約４ｇ／ｃｍ3であり、比較的緻密なヘマタイト鉱石で約５ｇ／ｃｍ3であることから、上記体積％を質量％で表すと、約４１質量％以上、約６３質量％以下が好適な濃度範囲であると換言できる。 From the above, the preferred concentration of iron ore particles in the iron ore slurry is preferably 15% by volume or more and 25% by volume or less. Here, the density of iron ore is about 4 g / cm 3 for relatively porous pisolite ore and maramamba ore, and about 5 g / cm 3 for relatively dense hematite ore. In other words, it can be said that a concentration range of about 41% by mass or more and about 63% by mass or less is a preferable concentration range.
　上述した本発明例における鉄鉱石スラリーは、密度が約４ｇ／ｃｍ3のＳＦ．Ａを用いたため、そのスラリー中の鉄鉱石粒子の濃度が２０体積％となるように粉砕したときに、鉄鉱石と水との重量比が約５０：５０であった。また、鉄鉱石スラリー中の鉄鉱石粒子に占める１０μｍ以下の極微粒子の比率は、上述したように造粒時に添加することができる水分に上限があるため、できる限り高い方が望ましい。しかし、スラリー中の鉄鉱石粒子における極微粒子の割合を上昇させると、所定粒度に到達するまで粉砕機から排出されずに循環する量が増加するので、粉砕効率や粉砕処理量が低下する。 The iron ore slurry in the above-described example of the present invention has a SF. Density of about 4 g / cm 3 . Since A was used, the weight ratio of iron ore to water was about 50:50 when pulverized so that the concentration of iron ore particles in the slurry was 20% by volume. Moreover, since the ratio of the ultrafine particles of 10 μm or less in the iron ore particles in the iron ore slurry has an upper limit on the moisture that can be added during granulation as described above, it is desirable that the ratio be as high as possible. However, when the ratio of the ultrafine particles in the iron ore particles in the slurry is increased, the amount of circulating fine particles without being discharged from the pulverizer until the predetermined particle size is reached increases, so that the pulverization efficiency and the pulverization amount are reduced.
　このため、本発明例では、それらのバランスを鑑みて、鉄鉱石粒子に占める１０μｍ以下の極微粒子の比率が５０質量％の鉄鉱石スラリーを用いた。しかし、粉砕機の能力が十分高ければ、粉砕処理量を維持しつつ極微粒子の比率を上昇することが比較的容易に可能と思われる。逆に、粉砕機の能力が低く極微粒子の比率が低い鉄鉱石スラリーしか供給できなくても、ペレットフィードの配合量に応じた所定の極微粒子量を添加することが可能なら問題ないと言える。 For this reason, in the present invention example, an iron ore slurry in which the ratio of ultrafine particles of 10 μm or less to the iron ore particles is 50% by mass is used in view of the balance between them. However, if the capacity of the pulverizer is sufficiently high, it seems that it is relatively easy to increase the ratio of ultrafine particles while maintaining the pulverization amount. On the contrary, even if only the iron ore slurry having a low pulverizer capacity and a low ratio of ultrafine particles can be supplied, it can be said that there is no problem if it is possible to add a predetermined amount of ultrafine particles according to the amount of pellet feed.
　上述の通りに製造した、従来例１～２、比較例１～３および本発明例の擬似粒子を、内径が３００ｍｍの焼結試験鍋に、原料層厚が５００ｍｍで重量が約６０ｋｇの規模となるように装入し、鍋焼結試験を行った。その際、鍋下圧力を２０ｋＰａとして吸引しながらＬＰＧバーナーにより１分間着火した後、鍋下圧力を９．８ｋＰａで一定として焼成を行い、排ガス温度が最高温度に到達してから３分後に吸引を停止し、これにより焼結ケーキを形成して焼成を完了した。焼結試験終了後、下記の手法により、焼結鉱生産率を求め、これを評価した。 The pseudo-particles of Conventional Examples 1-2, Comparative Examples 1-3, and Example of the Invention produced as described above were placed in a sintering test pot having an inner diameter of 300 mm, a raw material layer thickness of 500 mm, and a weight of about 60 kg. Then, a pot sintering test was conducted. At that time, after igniting with an LPG burner for 1 minute while sucking under a pan pressure of 20 kPa, firing was performed with the pan bottom pressure constant at 9.8 kPa, and suction was performed 3 minutes after the exhaust gas temperature reached the maximum temperature. Stopped, thereby forming a sintered cake and completing the firing. After completion of the sintering test, the sinter production rate was obtained and evaluated by the following method.
　焼結ケーキを直ちに焼結試験鍋から取り出し、焼結ケーキの温度が室温に低下するまで放冷した。冷却完了後に、製造された焼結ケーキを２ｍの高さから４回落下させた後に、篩目が５ｍｍの篩により篩ってその篩上の質量を測定し、焼結鉱生産率を求めた。ここで、焼結鉱生産率とは、５ｍｍの篩で篩った後の篩上の質量を、焼結機の有効面積および焼結時間で除した値を意味し、下記式（１）により算出される。このとき、鍋焼結試験の場合には、焼結機の有効面積として焼結試験鍋の横断面積を使用した。 The sintered cake was immediately removed from the sintering test pan and allowed to cool until the temperature of the sintered cake dropped to room temperature. After the cooling was completed, the produced sintered cake was dropped from a height of 2 m four times, and the sieve mesh was sieved with a 5 mm sieve to measure the mass on the sieve to obtain the sintered ore production rate. . Here, the sintered ore production rate means a value obtained by dividing the mass on the sieve after sieving with a 5 mm sieve by the effective area of the sintering machine and the sintering time. Calculated. At this time, in the case of the pot sintering test, the cross-sectional area of the sintering test pot was used as the effective area of the sintering machine.
　焼結鉱生産率（ｔｏｎ／ｍ2／ｄａｙ）＝［粒径が５ｍｍ以上の焼結鉱の質量（ｔｏｎ）／｛焼結機の有効面積（ｍ2）×焼結時間（分）｝］×６０×２４　・・・（１） Sinter production rate (ton / m 2 / day) = [mass of sintered ore with a particle size of 5 mm or more (ton) / {effective area of the sintering machine (m 2 ) × sintering time (min)}] × 60 × 24 (1)
　［従来例１］
　従来例１では、高品位の微粉鉄鉱石（ペレットフィード（ＰＦ．Ａ））を０質量％配合し、すなわちペレットフィードを配合することなく、全焼結原料を造粒系統Ａで造粒した。その後に焼結機に装入し焼成した。この場合の焼結鉱生産率を基準値（１００）とし、以下では、この基準値に対する焼結鉱生産率の比（以下、「相対生産率」という）で比較し、それぞれの場合の焼結鉱生産率を評価した。 [Conventional example 1]
In Conventional Example 1, 0% by mass of high-grade fine iron ore (pellet feed (PF.A)) was blended, that is, the entire sintered raw material was granulated in the granulation system A without blending the pellet feed. Thereafter, it was charged into a sintering machine and fired. In this case, the sinter production rate is defined as a reference value (100). In the following, the ratio of the sinter production rate to the reference value (hereinafter referred to as “relative production rate”) is compared. Mining production rate was evaluated.
　図６は、鍋焼結試験による焼結鉱の生産率の評価結果を示す図である。同図では、上記の通りに、従来例１の場合の焼結鉱生産率を基準値（１００）とし、この基準値に対し、従来例２、比較例１～３および本発明例それぞれの場合の焼結鉱生産効率を相対値で示している。 FIG. 6 is a diagram showing the evaluation result of the production rate of sintered ore by the pot sintering test. In the figure, as described above, the sinter production rate in the case of the conventional example 1 is set as the reference value (100), and the case of the conventional example 2, the comparative examples 1 to 3 and the present invention example with respect to this reference value. The sinter production efficiency is shown as a relative value.
　［従来例２］
　従来例２では、高品位の微粉鉄鉱石（ペレットフィード（ＰＦ．Ａ））の配合率を５．００、１０．００、２０．００質量％の３条件とし、全焼結原料を造粒系統Ａで造粒した。その後に焼結機に装入し焼成した。従来例２の場合、ペレットフィードの配合率の上昇に伴い、相対生産率は低下した。図６に示すように、特に、ペレットフィードを２０．００質量％配合した場合、相対生産率は７０を下回っており、ペレットフィードの多量配合によって大幅に生産率が悪化していることが確認できた。 [Conventional example 2]
In Conventional Example 2, the blending ratio of high-grade fine iron ore (pellet feed (PF.A)) is 3 conditions of 5.00, 10.00, 20.00 mass%, and all sintered raw materials are granulated line A Granulated with. Thereafter, it was charged into a sintering machine and fired. In the case of Conventional Example 2, the relative production rate decreased with an increase in the blending rate of the pellet feed. As shown in FIG. 6, in particular, when 20.00% by mass of pellet feed is blended, the relative production rate is less than 70, and it can be confirmed that the production rate is greatly deteriorated by blending a large amount of pellet feed. It was.
　［比較例１］
　比較例１では、高品位の微粉鉄鉱石（ペレットフィード（ＰＦ．Ａ））の配合率を５．００、１０．００、２０．００質量％の３条件とし、全焼結原料を造粒系統Ａで造粒する際に、バインダーとして生石灰を３．００質量％添加した。その後に焼結機に装入し焼成した。図６に示すように、比較例１の場合、生石灰の添加によって相対生産率は全体的に上昇したが、ペレットフィードを２０．００質量％配合した場合は、生石灰を３．００質量％と非常に多量に添加したにもかかわらず、相対生産率は１００に届かなかった。 [Comparative Example 1]
In Comparative Example 1, the blending ratio of high-grade fine iron ore (pellet feed (PF.A)) is set to three conditions of 5.00, 10.00, and 20.00 mass%, and all sintered raw materials are granulated system A. When granulating, 3.00% by mass of quick lime was added as a binder. Thereafter, it was charged into a sintering machine and fired. As shown in FIG. 6, in the case of Comparative Example 1, the relative production rate was increased as a whole by the addition of quicklime, but when 20.00% by mass of pellet feed was blended, quicklime was very 3.00% by mass. The relative production rate did not reach 100 even though a large amount was added.
　［比較例２］
　比較例２では、高品位の微粉鉄鉱石（ペレットフィード（ＰＦ．Ａ））を合計で１３．２０質量％配合して造粒した。すなわち、造粒系統Ｂでペレットフィードを９．３５質量％含む全焼結原料の２０．００質量％を造粒し、造粒系統Ａでペレットフィードを３．８５質量％含む全焼結原料の残り８０．００質量％を造粒した。その際、生石灰を合計で１．８０質量％添加した。その後に造粒系統Ａおよび造粒系統Ｂの両者を混合して焼結機に装入し焼成した。図６に示すように、比較例２の結果から、ペレットフィードを１３．２０質量％配合するまでは、相対生産率を従来例１と同等に維持することが確認できた。 [Comparative Example 2]
In Comparative Example 2, high-quality fine iron ore (pellet feed (PF.A)) was blended in a total of 13.20% by mass and granulated. That is, granulation system B granulates 20.00% by mass of the total sintered raw material containing 9.35% by mass of pellet feed, and granulation system A holds the remaining 80% of the total sintered raw material containing 3.85% by mass of pellet feed. 0.000 mass% was granulated. At that time, 1.80% by mass of quicklime was added in total. Thereafter, both the granulation system A and the granulation system B were mixed, charged into a sintering machine, and fired. As shown in FIG. 6, from the result of Comparative Example 2, it was confirmed that the relative production rate was maintained equal to that of Conventional Example 1 until 13.20 mass% of the pellet feed was blended.
　［比較例３］
　比較例３では、高品位の微粉鉄鉱石（ペレットフィード（ＰＦ．Ａ））を合計で２０．００質量％配合して造粒した。すなわち、造粒系統Ｂでペレットフィードを９．３５質量％含む全焼結原料の２０．００質量％を造粒し、造粒系統Ａでペレットフィードを１０．６５質量％含む全焼結原料の残り８０．００質量％を造粒した。その際、生石灰を合計で１．８０質量％添加した。その後に造粒系統Ａおよび造粒系統Ｂの両者を混合して焼結機に装入し焼成した。図６に示すように、比較例３の結果から、ペレットフィードを２０．００質量％まで配合した場合は、造粒系統Ｂを併用し、かつ生石灰を合計で１．８０質量％添加しても、相対生産率は約８４％までしか届かないことが確認できた。 [Comparative Example 3]
In Comparative Example 3, high-quality fine iron ore (pellet feed (PF.A)) was blended in a total amount of 20.00% by mass and granulated. That is, granulation system B granulates 20.00% by mass of the total sintered raw material containing 9.35% by mass of pellet feed, and granulation system A has the remaining 80% of the total sintered raw material containing 10.65% by mass of pellet feed. 0.000 mass% was granulated. At that time, 1.80% by mass of quicklime was added in total. Thereafter, both the granulation system A and the granulation system B were mixed, charged into a sintering machine, and fired. As shown in FIG. 6, from the result of Comparative Example 3, when the pellet feed was blended up to 20.00% by mass, the granulation system B was used in combination and quick lime was added in a total of 1.80% by mass. It was confirmed that the relative production rate reached only about 84%.
　［本発明例］
　本発明例では、高品位の微粉鉄鉱石（ペレットフィード（ＰＦ．Ａ））を合計で２０．００％配合して造粒した。すなわち、造粒系統Ｂでペレットフィードを１４．００質量％（造粒系統Ｂの焼結原料中の７０質量％）含む全焼結原料の２０．００質量％を造粒し、造粒系統Ａでペレットフィードを６．００質量％含む全焼結原料の残り８０．００質量％を造粒した。その際、生石灰を合計で１．８０質量％添加した。さらに、造粒系統Ｂで鉄鉱石スラリーを添加した。すなわち、この例では、焼結原料の一部であって微粉鉄鉱石を５０質量％以上含む部分に、鉄鉱石スラリーを添加した。このとき、鉄鉱石スラリーは、当該鉄鉱石スラリー中の水分を除く鉄鉱石の重量が、全焼結原料に対し０．４０質量％となるように添加した。上述の通り、鉄鉱石スラリーにおける鉄鉱石中の極微粒子の比率は５０質量％であるため、配合した焼結原料中のペレットフィード１．０質量％あたり、１０μｍ以下の極微粒子は０．０１質量％添加したことになる。図６に示すように、本発明例の場合、鉄鉱石スラリーの添加により、ペレットフィードを２０．００質量％配合しても、相対生産率を従来例１と同等に維持することができた。 [Example of the present invention]
In the example of the present invention, high-quality fine iron ore (pellet feed (PF.A)) was blended in a total amount of 20.00% and granulated. That is, granulation system B granulates 20.00% by mass of the total sintering raw material including 14.00% by mass of pellet feed (70% by mass in the sintering raw material of granulation system B). The remaining 80.00% by mass of the total sintered raw material containing 6.00% by mass of pellet feed was granulated. At that time, 1.80% by mass of quicklime was added in total. Furthermore, iron ore slurry was added in the granulation system B. That is, in this example, the iron ore slurry was added to a part of the sintering raw material that contained 50% by mass or more of fine iron ore. At this time, the iron ore slurry was added such that the weight of the iron ore excluding moisture in the iron ore slurry was 0.40% by mass with respect to the total sintered raw material. As described above, since the ratio of the ultrafine particles in the iron ore in the iron ore slurry is 50% by mass, the ultrafine particles of 10 μm or less per 0.01% by mass of the pellet feed in the blended sintered raw material are 0.01% by mass. % Is added. As shown in FIG. 6, in the case of the example of the present invention, the relative production rate could be maintained equal to that of the conventional example 1 even when the pellet feed was mixed at 20.00% by mass by adding the iron ore slurry.
　すなわち、本発明例の場合においては、比較例１～３の場合では相対生産率が低下した、ペレットフィードの配合率が１３．２０質量％より高い範囲においても、ペレットフィード１．０質量％に対し鉄鉱石スラリー中の極微粒子が０．０１質量％以上となるように、鉄鉱石スラリーを添加することによって、ペレットフィードを２０．００質量％まで配合しても焼結鉱の生産率を維持できることがわかった。 That is, in the case of the present invention example, the relative feed rate decreased in the case of Comparative Examples 1 to 3, and the pellet feed was reduced to 1.0% by mass even in the range where the blending rate of the pellet feed was higher than 13.20% by mass. On the other hand, by adding the iron ore slurry so that the ultrafine particles in the iron ore slurry become 0.01% by mass or more, the production rate of sintered ore is maintained even if the pellet feed is blended up to 20.00% by mass. I knew it was possible.
　また、実際の焼結操業においては、返鉱を炭材と同様に外数で表した、いわゆる新原料の量を１００質量％として表した新原料ベースの配合率が良く用いられる。新原料ベースの配合率で考えた場合、本発明例によってペレットフィードを２５質量％まで配合しても生産率が維持されると言える。 Also, in the actual sintering operation, a new raw material-based blending ratio in which the amount of so-called new raw material is expressed as 100% by mass, in which the return ore is expressed in the same manner as the carbonaceous material, is often used. Considering the blending rate based on the new raw material, it can be said that the production rate is maintained even if the pellet feed is blended up to 25% by mass according to the present invention.
　以上の知見から、本発明の焼結原料の造粒方法は、上述の通り、回転駆動する鉛直中心軸にスクリュー翼を備えた円筒容器からなる粉砕部と、重力および遠心力の作用により分級する分級部と、分級部で分級したアンダーフローを粉砕部の円筒容器に循環させる循環部と、を有する竪型粉砕機を用いて鉄鉱石を湿式粉砕し、この湿式粉砕してなる鉄鉱石スラリーを焼結原料の全部または一部に添加して造粒することを特徴とする。 From the above knowledge, the granulation method of the sintered raw material of the present invention is classified by the action of gravity and centrifugal force, as described above, and a pulverizing part composed of a cylindrical container provided with screw blades on the vertical center shaft to be rotationally driven. Iron ore is wet pulverized using a vertical pulverizer having a classification part and a circulation part that circulates the underflow classified in the classification part to the cylindrical container of the pulverization part, and the iron ore slurry formed by wet pulverization is obtained. It is characterized by adding to all or part of the sintering raw material and granulating.
　この場合、前記焼結原料は、粒子径２５０μｍ以下の比率が８０質量％以上であってＴ．Ｆｅ（全鉄）を６０質量％以上含有する特定銘柄の微粉鉄鉱石（例：ペレットフィード）を、少なくとも全焼結原料中に１３．２０質量％よりも高く２０．００質量％以下で含有しており、この焼結原料の全部または一部に、前記鉄鉱石スラリー中の鉄鉱石のうちで粒子径が１０μｍ以下である極微粒子の量が、前記微粉鉄鉱石１．０質量％に対して０．０１質量％以上となるように、前記鉄鉱石スラリーを添加して造粒することが好ましい。 In this case, the sintering raw material has a ratio of particle size of 250 μm or less of 80% by mass or more and T.I. A specific brand of fine iron ore containing 60% by mass or more of Fe (total iron) (eg, pellet feed) is contained at least higher than 13.20% by mass and less than 20.00% by mass in all sintered raw materials. The amount of ultrafine particles having a particle size of 10 μm or less among the iron ore in the iron ore slurry is 0% relative to 1.0% by mass of the fine iron ore. It is preferable to granulate by adding the iron ore slurry so as to be 0.01 mass% or more.
　以下に、本発明の造粒方法を採用した焼結鉱の製造の概要を示す。例えば、焼結原料は、高品質の微粉鉄鉱石として多量のペレットフィードを含む鉄鉱石、副原料、返鉱、炭材などの原料から構成され、造粒系統Ａ、造粒系統Ｂ、および破砕系統の三系統に分割される。造粒系統Ａの原料は、ドラムミキサーからなる造粒機により造粒されて擬似粒子とされる。造粒系統Ｂの原料は、高速攪拌ミキサーにより混合調湿された後、パンペレタイザーにより造粒されて粗大擬似粒子とされる。 The following outlines the production of sintered ore that employs the granulation method of the present invention. For example, the sintering raw material is composed of raw materials such as iron ore containing a large amount of pellet feed as a high-quality fine iron ore, auxiliary raw material, return ore, carbonaceous material, etc., and granulation system A, granulation system B, and crushing Divided into three systems. The raw material of the granulation system A is granulated by a granulator composed of a drum mixer into pseudo particles. The raw material of the granulation system B is mixed and humidity-controlled by a high-speed stirring mixer, and then granulated by a pan pelletizer into coarse pseudo particles.
　ここで、破砕系統の原料は、予め、竪型粉砕機であるタワーミルを用いた湿式粉砕によって水と共に粉砕混合され、鉄鉱石スラリーとされる。破砕系統で製造された鉄鉱石スラリーは、造粒系統Ｂの造粒にあたり、造粒系統Ｂの原料と共に高速撹拌ミキサーに添加され、造粒系統Ｂの原料が造粒される際のバインダーとなる。各々の造粒系統の造粒によって製造された擬似粒子は、サージホッパーに装入される過程で混合され、さらに、ロールフィーダにより切り出される過程、および焼結機のパレット上に落下堆積して焼結原料充填層を形成する過程で混合される。 Here, the raw material of the crushing system is preliminarily pulverized and mixed with water by wet pulverization using a tower mill, which is a vertical pulverizer, to obtain iron ore slurry. The iron ore slurry produced in the crushing system is added to the high-speed stirring mixer together with the raw material of the granulation system B in the granulation of the granulation system B, and becomes a binder when the raw material of the granulation system B is granulated. . Pseudoparticles produced by granulation of each granulation system are mixed in the process of being charged into the surge hopper, further cut out by the roll feeder, and dropped and deposited on the pallet of the sintering machine. It is mixed in the process of forming the binder filling layer.
　このようにして形成された焼結原料充填層は、点火炉でその上部表面に着火され、給鉱部から排鉱部へと移動する間に下方からの空気吸引により、充填層の上部から下部まで順次焼成される。焼成後の焼結ケーキは、焼結機の排鉱部から排鉱され、クラッシャーにより破砕され、クーラーにより冷却された後、篩により整粒されて高炉に搬送される。 The sintered raw material packed layer thus formed is ignited on the upper surface in an ignition furnace, and while moving from the supply section to the discharge section, air suction from below causes the upper to lower portion of the packed bed. Are fired sequentially. The sintered cake after firing is discharged from the discharge portion of the sintering machine, crushed by a crusher, cooled by a cooler, sized by a sieve, and conveyed to a blast furnace.
　本発明では、焼結原料に添加する鉄鉱石スラリーを製造する手法として湿式粉砕を採用しているが、これは以下の理由による。上述の通り、極微粒子のバインダー効果の発現メカニズム上、極微粒子は、添加水分と良く混ざり合っていることが要求される。この点、湿式粉砕は、鉄鉱石を粉砕し、粉砕した極微粒子の水中への懸濁を分散剤等の使用なしに実現できることから、その要求を満たす優れた手法である。 In the present invention, wet pulverization is adopted as a technique for producing an iron ore slurry to be added to a sintering raw material, for the following reason. As described above, the ultrafine particles are required to be well mixed with the added water because of the mechanism of manifestation of the binder effect of the ultrafine particles. In this respect, wet pulverization is an excellent technique that satisfies the requirements because it can pulverize iron ore and suspend the pulverized ultrafine particles in water without using a dispersant or the like.
　また、湿式粉砕には、竪型粉砕機であるタワーミルを用いる。上述の通り、タワーミルは、円周方向と垂直方向の複合的な撹拌によって大きい粉砕力を作用させることが可能であり、バインダー性状に優れる凹凸の多い形状を持つ極微粒子を製造することができるからである。 In addition, a tower mill which is a vertical pulverizer is used for wet pulverization. As described above, the tower mill can apply a large pulverization force by a composite stirring in the circumferential direction and the vertical direction, and can produce extremely fine particles having a shape with many irregularities that are excellent in binder properties. It is.
　本発明の焼結原料の造粒方法によれば、ペレットフィードといった特定銘柄の高品位な微粉鉄鉱石を多量に配合し、焼結原料の微粉比率が増加する場合であっても、充填層の通気性を確保でき、焼結鉱の生産性を安価に維持することができる。したがって、本発明は、高品位な粉鉄鉱石の枯渇にも対応できる技術として極めて有用である。 According to the granulation method of a sintered raw material of the present invention, a large amount of high-grade fine iron ore of a specific brand such as pellet feed is mixed, and even if the fine powder ratio of the sintered raw material is increased, Air permeability can be ensured, and the productivity of sintered ore can be maintained at low cost. Therefore, the present invention is extremely useful as a technique that can cope with the depletion of high-grade fine iron ore.
　　１：タワーミル（竪型粉砕機）、　　２：鉛直中心軸、
　　３：スクリュー翼、　　４：円筒容器、　　５：水簸槽、
　　６：サイクロン分級装置、　　７：循環ポンプ、　　８：配管、
　　９：配管 1: Tower mill (vertical crusher) 2: Vertical center axis
3: screw wing, 4: cylindrical container, 5: water tank
6: Cyclone classifier, 7: Circulation pump, 8: Piping,
9: Piping

Claims (2)

  1. 　鉄鉱石、炭材、副原料および返鉱を配合して焼結原料とし、当該焼結原料を混合、調湿および造粒処理するに際して、
    　回転駆動する鉛直中心軸にスクリュー翼を備えた円筒容器からなる粉砕部と、重力および遠心力の作用により分級する分級部と、分級部で分級したアンダーフローを粉砕部の円筒容器に循環させる循環部と、を有する竪型粉砕機を用いて鉄鉱石を湿式粉砕し、この湿式粉砕してなる鉄鉱石スラリーを焼結原料の全部または一部に添加して造粒することを特徴とする焼結原料の造粒方法。     When iron ore, carbonaceous material, auxiliary material and return ore are blended to form a sintered raw material, the sintered raw material is mixed, conditioned and granulated,
    A pulverization unit consisting of a cylindrical container with screw wings on a rotating vertical center axis, a classification part classified by the action of gravity and centrifugal force, and a circulation that circulates the underflow classified by the classification part to the cylindrical container The iron ore is wet pulverized using a vertical pulverizer and the iron ore slurry formed by wet pulverization is added to all or part of the sintering raw material and granulated. A granulation method for raw materials.
  2. 　前記焼結原料は、粒子径２５０μｍ以下の比率が８０質量％以上であってＴ．Ｆｅ（全鉄）を６０質量％以上含有する特定銘柄の微粉鉄鉱石を、少なくとも全焼結原料中に１３．２０質量％よりも高く２０．００質量％以下で含有しており、
    　この焼結原料の全部、またはこの焼結原料の一部であって当該微粉鉄鉱石を５０質量％以上含む部分に、前記鉄鉱石スラリー中の鉄鉱石のうちで粒子径が１０μｍ以下である極微粒子の量が、前記微粉鉄鉱石１．０質量％に対して０．０１質量％以上となるように、前記鉄鉱石スラリーを添加して造粒することを特徴とする請求項１に記載の焼結原料の造粒方法。     The sintering raw material has a ratio of particle size of 250 μm or less of 80% by mass or more, and T.I. A specific brand of fine iron ore containing 60% by mass or more of Fe (total iron) is contained at least higher than 13.20% by mass and not more than 20.00% by mass in all sintered raw materials,
    An electrode having a particle diameter of 10 μm or less among the iron ore in the iron ore slurry in the whole of the sintering raw material or a part of the sintering raw material and containing 50% by mass or more of the fine iron ore. The said iron ore slurry is added and granulated so that the quantity of microparticles | fine-particles may be 0.01 mass% or more with respect to 1.0 mass% of the said fine iron ore. A method for granulating sintered raw materials.
PCT/JP2012/005794 2011-10-11 2012-09-12 Method for granulation of sintering raw material WO2013054471A1 (en)

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Publication number Priority date Publication date Assignee Title
JP2016079467A (en) * 2014-10-17 2016-05-16 新日鐵住金株式会社 Production method of sintered ore
JP2016191122A (en) * 2015-03-31 2016-11-10 新日鐵住金株式会社 Method for producing sintered ore
JP2020158889A (en) * 2017-03-31 2020-10-01 Ｊｆｅスチール株式会社 Method for manufacturing granular sintered material, and method for manufacturing sintered ore
WO2019087530A1 (en) * 2017-10-30 2019-05-09 住友電気工業株式会社 Method for producing copper nanoparticles
JP2020066766A (en) * 2018-10-23 2020-04-30 Ｊｆｅスチール株式会社 Method for manufacturing sintered ore
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