KR102157943B1 - Manufacturing method of sintered ore - Google Patents

Abstract

By forming coarse pseudo-particles in the raw material for sintering containing pulverized iron ore, the productivity of the sintered ore decreases. As a manufacturing method of a sintered ore, with a high-speed stirring device having a rotating cylindrical container and a stirring blade rotating in the cylindrical container, the sintering raw material is stirred so as to satisfy the following equation (1), and the sintered raw material after the stirring treatment is The granulation apparatus is used to granulate, and the granulated sintered raw material is sintered using a sintering machine to produce a sintered ore. However, in the following equation (1), v: the peripheral speed of the bottom plate of the cylindrical container (m/s), u: the peripheral speed of the tip of the stirring blade (m/s), t: the raw material for sintering by a high-speed stirring device Stirring time (s), L: length of the circumference drawn by the tip of the stirring blade (m), S: subtracting the area of the circle drawn by the tip of the stirring blade from the projected area of the cylindrical container projected from the rotation axis direction of the stirring blade It is the area (㎡).

Description

Manufacturing method of sintered ore

The present invention relates to a method for producing a sintered ore sintered using a Dwight-Lloyd type sintering machine or the like.

The sintered ore is generally manufactured in the following three processes.

(1) For powdered iron ore of multiple brands (called sinter feed, concentrate and pellet feed, etc.), auxiliary raw material powder such as limestone, silica stone, serpentine, and miscellaneous raw material powder such as dust, scale, semi-gloss, and powder coke As a raw material for sintering, solid fuels such as etc. are mixed in an appropriate amount.

(2) After adding moisture to the raw material for sintering, granulate (造粒).

(3) The sintered raw material after granulation is charged into a sintering machine and sintered.

When the raw materials for sinter contain moisture, they aggregate with each other at the time of granulation and become pseudo-particles. And this pseudo-particle-formed sintering raw material, when charged to the pallet of the sintering machine, helps to ensure good air permeability of the charged layer, so that the sintering reaction proceeds smoothly.

Powdered iron ores for sintering have recently been degraded due to depletion of high-quality iron ores. That is, in the sintered powdered iron ore, the proportion of the pulverized iron ore is increasing as the slag component increases. The increase in the content of alumina, which is one of the slag components in the sintered powdered iron ore, and the increase in the proportion of the pulverized iron ore, causes a decrease in the granularity of the sintered powdered iron ore. On the other hand, as the sintered ore used in the blast furnace, from the viewpoint of reducing the cost of manufacturing molten iron in the blast furnace and reducing the amount of CO ₂ generated, sintered ore having a low slag ratio, high reduction rate and high strength is required.

Under such an environment surrounding powdered iron ore for sintering, a technique for producing a high-quality sintered ore using pulverized iron ore having difficulty in assembly has been proposed. For example, as one of these technologies, there is a Hybrid Pelletized Sinter method (hereinafter referred to as "HPS method"). The HPS method is a method of using a drum mixer and a disk pelletizer in the granulation process of raw materials for sintering, and Patent Documents 1 to 5 include a sintered blended raw material containing a large amount of pulverized iron ore having a high iron content in a drum mixer and a disk pellet tie. It is disclosed to produce a sintered ore having a low slag ratio and a high reduction rate by granulating using a low. In addition, Patent Document 6 discloses a method of humidifying mixing with a high-speed rotary mixer before the granulation process of the sintered raw material powder, and Patent Document 7 previously mixing pulverized iron ore and iron making dust with a stirring mixer before the granulation process. A method is disclosed, and in Patent Document 8, a method of granulating a pulverized iron ore with a drum mixer after premixing treatment with an Eirich mixer is disclosed.

Japanese Patent Publication No. Hei 2-4658 Japanese Patent Publication No. Hei 6-21297 Japanese Patent Publication No. Hei 6-21298 Japanese Patent Publication No. Hei 6-21299 Japanese Patent Publication No. Hei 6-60358 Japanese Laid-Open Patent Publication No. 60-52534 Japanese Patent Laid-Open Publication No. Hei 1-312036 Japanese Laid-Open Patent Publication No. Hei 7-331342

The raw material for sinter containing a large amount of pulverized iron ore, such as a pellet feed having a particle diameter of 0.125 mm or less, aggregates to form coarse pseudo particles. When a raw material for sinter having coarse pseudo-particles is granulated using a granulating device, the particle diameter becomes uneven, and granulated particles with weak bonding strength, which are merely agglomerated between pulverized iron ores, are easily granulated.

When such granulated particles are charged to a pallet of a sintering machine to form a charged layer, the charged layer has a dense sediment structure, the bulk density increases, and the air permeability in the charged layer is deteriorated. Furthermore, when such particles are deposited on a pallet of a sintering machine with a certain layer thickness, a load (compressive force) is applied to the particles, so that they are easily destroyed and differentiated, and the gap forming the charged layer. This becomes small, and the porosity decreases. When this porosity decreases, the air permeability in the charged layer deteriorates. The deterioration of the air permeability of the charged layer extends the sintering time of the raw material for sintering, thereby reducing the productivity of the sintered ore. As described above, formation of coarse pseudo-particles in the raw material for sintering causes a decrease in productivity of the sintered ore.

In the method of granulating using the HPS method described in Patent Documents 1 to 5, coarse pseudo-particles contained in the raw materials for sinter cannot be crushed. Moreover, even if a method of mixing treatment in advance using a high-speed stirrer described in Patent Documents 6 to 8 is used, there has been a problem that the coarse pseudo-particles contained in the sintering raw material cannot be sufficiently crushed, and the productivity of the sintered ore decreases.

The present invention has been made in view of the above problems faced by the prior art, and its object is to remove coarse pseudo particles contained in the raw materials for sintering by using a high-speed stirring device when using a raw material for sinter containing pulverized iron ore. It is to provide a method for producing a sintered ore which is pulverized before granulation to improve productivity in a sintering machine.

The features of the present invention for solving such a problem are as follows.

[1] As a manufacturing method of sintered ore, with a high-speed stirring device having a rotating cylindrical container and a stirring blade rotating in the cylindrical container, a sintering raw material is stirred so as to satisfy the following formula (1), and after the stirring treatment A method for producing a sintered ore, in which a raw material for sinter is granulated using a granulating device, and the raw material for sintered after granulation is sintered using a sintering machine to produce a sintered ore.

[Equation 1]

However, in the above equation (1),

v: peripheral speed of the bottom plate of the cylindrical container (m/s),

u: peripheral speed of the tip of the stirring blade (m/s),

t: time (s) for the sintering raw material to be stirred by a high-speed stirring device,

L: the length of the circumference drawn by the tip of the stirring blade (m),

S: It is the area (m 2) obtained by subtracting the area of the circle drawn by the tip of the stirring blade from the projected area of the cylindrical container projected from the rotation axis direction of the stirring blade.

[2] The sintered ore according to [1], wherein the sintered raw material contains 10 to 50 mass% of pulverized iron ore having a particle diameter of 0.125 mm or less, and the Al ₂ O ₃ concentration of the sintered ore sintered with the sintering machine is 1.6 mass% or more. Manufacturing method.

[3] The method for producing a sintered ore according to [1] or [2], wherein the sintering raw material further contains a binder.

[4] The method for producing the sintered ore according to [3], wherein the binder is quicklime.

[5] The method for producing a sintered ore according to any one of [1] to [4], wherein the average particle diameter of the sintered raw material after the stirring treatment is performed with the high-speed stirring device is 3 mm or less.

[6] The method for producing a sintered ore according to [5], wherein the raw material for sintering before being subjected to agitation treatment by the high-speed stirring device contains 7% by mass or less of water.

Even if it is a raw material for sinter containing pulverized iron ore, coarse pseudo-particles can be crushed before granulation by producing by the method for producing a sintered ore of the present invention. Thereby, even if the granulated raw material for sintering after that is charged to the pallet of the sintering machine to form a charged layer, the air permeability of the charged layer is not deteriorated. This shortens the sintering time conventionally required for sintering the raw material for sintering in a poorly ventilated state, so that the productivity of the sintered ore in the sintering machine can be improved.

1 is a graph showing a difference in particle size distribution of pseudo particles in the presence or absence of a pellet feed.
Fig. 2(a) is a graph showing the difference in particle size distribution of granulated particles in the presence or absence of a pellet feed, (b) is a graph showing the distribution of pellet feed in the granulated particles, and (c) is, It is a graph showing the dispersion state of moisture in the granulated particles.
Fig. 3(a) shows a cross-sectional view of a conventional charged layer of granulated particles, and (b) is a cross-sectional view of a charged layer of granulated particles of the present invention.
4 is an internal perspective view of the high-speed stirring device 10.
5 is a plan view of the high-speed stirring device 10.
6 is a diagram illustrating L and S in the high-speed stirring device 10.
7 is a graph showing the relationship between the content of pulverized iron ore having a particle diameter of 0.125 mm or less and a sintered production rate.
8 is a graph showing the relationship between Experimental Examples 1 to 4 and the effect of improving the production rate.
9 is a graph showing the relationship between the stirring speed and the effect of improving the sintering production rate.
10 is a graph showing the relationship between the average particle diameter after the stirring treatment and the effect of improving the sintering production rate.
Fig. 11 is a diagram showing a relationship between moisture in the stirring treatment and average particles after the stirring treatment.

The present invention is to disintegrate in advance coarse pseudo-particles generated by agglomeration of pulverized iron ore by performing agitation treatment using a high-speed stirring device before granulating a raw material for sinter containing pulverized iron ore. First, the characteristics of the raw material for sinter containing pulverized iron ore that generate coarse pseudo particles will be described.

1 is a graph showing a difference in particle size distribution of pseudo particles in the presence or absence of a pellet feed.

The black plot in FIG. 1 shows the particle size distribution of iron ore to which pellet feed, which is a pulverized iron ore, is not blended. In addition, the white plot shows the particle size distribution of the iron ore in which the particle size distribution was shown in the black plot and 40% by mass of pellet feed was blended.

As shown in Fig. 1, when 40 mass% of pellet feeds having a particle diameter of 0.125 mm or less were blended and mixed, the particle size distribution indicated by the black plot became the particle size distribution indicated by the white plot. That is, by mixing 40 mass% of the pellet feed, not only fine (less than 0.5 mm) but coarse (more than 10 mm) pseudo-particles were produced. If the wettability of the pulverized iron ore is the same, the finer the grain, the larger the specific surface area, so it absorbs more moisture, and thus retains a lot of moisture between the powders. For this reason, pulverized iron ore absorbs moisture preferentially with respect to iron ores other than pulverized iron ore. In addition, as the pulverized iron ores are agglomerated while absorbing moisture, fine pseudo-particles in which pulverized iron ores are simply agglomerated, or coarse pseudo-particles with pulverized iron ores attached around the nuclear particles are generated, resulting in uneven particle diameter. . In the present embodiment, the particle size and mass ratio are divided into each particle size by sifting through a sieve with graduated intervals according to JIS Z 8801, and the mass of each particle size is measured, respectively, and the mass of each particle size and From the total mass, the mass ratio of each particle size is calculated. For example, "40 mass% of a pellet feed having a particle diameter of 0.125 mm or less is blended" means that the pellet feed passed through a sieve having a nominal graduation spacing of 125 µm in accordance with JIS Z 8801 is 40 in terms of the total mass of the iron ore. It means mixing so that it may become mass %.

Next, the granulated particles obtained by granulating the raw material for sinter containing the coarse pseudo particles shown in Fig. 1 using a drum mixer will be described. Moisture was added to the spectrograph in which 40% by mass of a pellet feed having a particle diameter of 0.125 mm or less was blended, and a spectrograph containing no pellet feed, respectively, was granulated using a drum mixer, and the particle size distribution of each granulated particle was measured.

Fig. 2(a) is a graph showing a difference in particle size distribution of granulated particles in the presence or absence of a pellet feed. Fig. 2(b) is a graph showing the distribution of pellet feed in granulated particles. Fig. 2(c) is a graph showing the state of dispersion of moisture in granulated particles.

As shown in Fig. 2(a), when a sintered raw material containing 40 mass% of pellet feed in iron ore is granulated, compared to a sintered raw material not containing pellet feed, granulated (8 mm) contained in the granulated particles Excess) increased. The content ratio of the granules reached about 75% by mass with respect to the total amount of the raw materials for sinter. In addition, as shown in Fig. 2(b), the pellet feed in the granulated particles was widely distributed in granules in the same way as the particle size distribution of the granulated particles. That is, the amount of pellet feed contained in granulation was as high as about 75% by mass relative to the total amount of the pellet feed charged, and it was found that most of the pellet feed was unevenly distributed in the granulation. From this, it was found that the granules contained in the granulated particles were formed by pseudo particles in which pellet feeds were aggregated.

In addition, as shown in Fig. 2(c), it was found that the granules contained in the granulated particles contained a large amount of moisture. The pellet feed preferentially absorbs moisture with respect to other iron ores, and forms granules in the granulated particles. As described above, the granules containing a large amount of moisture are hardly bound by a binder or the like, and the bonding strength of the granules is weakened.

When the sintered raw material containing pulverized iron ore is granulated in this way, the particle diameter becomes uneven and the granulation with weak bonding strength is granulated. When the granulated particles containing such granules are charged into the pallet of the sintering machine, fine particles enter between granules to form a dense sediment structure, and a charging layer having a low porosity and high bulk density is formed. In addition, when such granules are deposited on a pallet of a sintering machine at a constant layer thickness, a load (compressive force) is applied to the granules, so that they are easily broken and differentiated, and the porosity of the charged layer is lowered. As a result, as shown in Fig. 3(a), the air permeability of the charged layer is deteriorated, and as a result, the sintering time of the raw material for sintering is prolonged and the productivity of the sintered ore is lowered. In addition, in FIG. 3, the arrow represents the ventilation path in the charged layer.

Even with such a sintered raw material containing pulverized iron ore, coarse pseudo-particles can be sufficiently pulverized by stirring under specific conditions using a high-speed stirring device prior to granulation, whereby the particle diameter is uneven in the subsequent granulation process. The present invention was completed by finding that it is possible to suppress the assembly of the assembly with weak bonding strength. When the granulated particles thus granulated are charged to the pallet of the sintering machine, the air permeability of the charged layer is improved as shown in Fig. 3(b), and as a result, the productivity of the sintered ore can be improved.

Next, the configuration of the high-speed stirring device 10 for crushing coarse pseudo particles will be described. 4 is an internal perspective view of the high-speed stirring device 10. In addition, FIG. 5 is a plan view of the high-speed stirring device 10. The high-speed stirring device 10 is a device for stirring the sintering raw material 40. The high-speed stirring device 10 has the cylindrical container 20 into which the sintering raw material 40 is charged, the stirring blade 30, and the weir 36. In addition, although it is preferable to form the weir 36 in order to scrape off a sintering raw material, it may not exist. The cylindrical container 20 includes a cylindrical cylinder 22 and a circular bottom plate 24. Further, the cylindrical container 20 is provided with an opening (not shown) for supplying and discharging the sintering raw material 40. The bottom plate 24 is formed integrally with the cylinder 22, and the bottom plate 24 rotates together with the cylinder 22 by receiving a driving force. Moreover, the cylindrical container 20 may be provided with the top plate which seals the upper side of the cylindrical container 20.

In addition, in this embodiment, the sintering raw material 40 contains solid fuels such as pulverized iron ore, limestone, and powder coke, and additionally, auxiliary raw materials such as silica stone and serpentine powder, dust, scale, semi-gloss, etc. You may contain miscellaneous raw material powder and a binder. In addition, the pulverized iron ore in the sintering raw material 40 is a pulverized iron ore having a particle diameter of 0.125 mm or less.

The stirring blade 30 includes a rotating shaft 32 and a plurality of stirring plates 34. The rotation shaft 32 is a position eccentric from the center of the cylindrical container 20, and the stirring blade 30 rotates by receiving a driving force from a drive part (not shown) formed on the upper side of the cylindrical container 20. Therefore, the stirring blade 30 and the bottom plate 24 can each independently rotate. In addition, the rotation shaft 32 may be formed in the center of the cylindrical container 20.

The stirring plate 34 is formed to protrude radially outward from the rotation shaft 32. The stirring plate 34 is formed in six directions at intervals of 60° at two points in the vertical direction on the rotation shaft 32. Therefore, 12 stirring plates 34 in total are formed in the stirring blade 30. In addition, the number of the stirring plates 34 is not limited to 12, and may be arbitrarily set depending on the shape of the stirring plate 34, the number of revolutions of the stirring blade 30 or the number of revolutions of the bottom plate 24. . For example, the stirring plate 34 may be provided with 8 to 16 sheets at 4 to 8 points in the vertical direction of the stirring shaft 32. Moreover, the interval between the angle and height of the stirring plate 34 may also be set arbitrarily.

In the state where the sintering raw material 40 is charged in the cylindrical container 20, the bottom plate 24 rotates, for example, in a clockwise direction, and the stirring blade 30 rotates in a counterclockwise direction. When the bottom plate 24 rotates in the clockwise direction, the sintered raw material 40 charged in the cylindrical container 20 rotates clockwise along the rotation direction of the bottom plate 24. The sintered raw material 40 rotated in the clockwise direction is stirred by colliding with the stirring blade 30 rotated in the counterclockwise direction. In addition, the rotation direction of the bottom plate 24 and the stirring blade 30 may be clockwise or counterclockwise. In addition, the rotation directions of the bottom plate 24 and the stirring blade 30 may be different from each other or may be the same.

In addition, in FIGS. 4 and 5, the high-speed stirring device 10 has shown an example in which the sintered raw material 40 is stirred in a horizontally installed state, but the high-speed stirring device 10 may be tilted and used. In addition, the stirring blade 30 may be used by tilting only the cylindrical container 20 while being supported in the vertical direction.

As described above, when the raw material for sinter 40 contains pulverized iron ore, the pulverized iron ore aggregates to generate coarse pseudo particles. By using the high-speed stirring device 10 described above, the sintering raw material 40 is stirred in advance to disintegrate coarse pseudo-particles, and the pulverized iron ore can be dispersed in the sintering raw material 40.

Subsequently, the stirring conditions of the high-speed stirring device 10 are demonstrated. Before producing a sintered ore with a sintering machine, the sintering raw material 40 is granulated by processing for a predetermined time using a drum mixer. Before being granulated by a drum mixer, the coarse pseudo-particles contained in the raw material for sintering 40 are crushed using the high-speed stirring device 10. This is to suppress granulation in the drum mixer by crushing the pulverized iron ore, which is easy to retain moisture and tends to adhere, before assembling with a drum mixer to reduce coarse pseudo-particles. In addition, the drum mixer is an example of a granulation device, and a general granulator, especially an electric granulator may be used.

When the particle motion of the sintered raw material 40 in the high-speed stirring device 10 was analyzed, the sintered raw material 40 in the cylindrical container 20 collides with the tip end of the stirring plate 34, and the stirring blade 30 ), it was found that even if it entered the inside of the circle drawn by the tip of the stirring plate 34, it only entered half the length of the blade. From this, since it is thought that the sintering raw material 40 is stirred on the circumference drawn by the tip of the stirring plate 34, when the length L of the circumference drawn by the tip of the stirring plate 34 becomes long, the cylindrical container 20 Since the sintering raw material 40 can be stirred more, the stirring efficiency of the high-speed stirring device 10 becomes high. Thereafter, the length L of the circumference drawn by the tip end of the stirring plate 34 is referred to as "effective blade length".

Further, in the case where the stirring shaft 32 of the stirring blade 30 is vertically formed with respect to the bottom plate 24, the area of the circle drawn by the tip of the stirring blade 30 is subtracted from the area of the bottom plate 24 When the area is S (m 2 ), the sintering raw material 40 exists in the S region. Since the sintering raw material 40 existing in the region of S does not contact the stirring plate 34 unless it reaches the circumference drawn by the tip of the stirring plate 34, the high-speed stirring device 10 is conversely when S increases. The stirring efficiency of is lowered. Thereafter, the area S obtained by subtracting the area of the circle drawn by the tip end of the stirring blade 30 from the area of the bottom plate 24 is referred to as "effective area". In addition, in the case where the stirring shaft 32 is formed inclined with respect to the bottom plate 24, the bottom plate 24 projected from the direction of the rotation shaft 32 is projected onto a plane perpendicular to the stirring shaft 32. The area calculated by the difference between the area and the area of the circle drawn by the tip end of the stirring blade 30 may be used as the effective area.

As described above, when the effective blade length L increases, the stirring efficiency increases, and when the effective area S increases, the stirring efficiency decreases. From this, "L/S", which is a value obtained by dividing L by S, was taken as an index showing the agitation efficiency in the structure of the high-speed stirring device 10.

6: is a figure explaining the effective blade length L and the effective area S in the high-speed stirring device 10. L is the length of the circumference of the circle 50 drawn by the tip end of the stirring plate 34 of the stirring blade 30 in FIG. 6. S is an area 52 indicated by an oblique line in FIG. 6. This is an area obtained by subtracting the area occupied by the motion of the stirring blade 30 from the projected area of the container from the direction of the rotation axis of the stirring blade 30.

In addition, when there are a plurality of stirring blades 30, the effective blade length L is the sum of the lengths of the circumferences drawn by the tip ends of the stirring plates 34 in the plurality of stirring blades 30, respectively. In addition, when there are a plurality of stirring blades 30, the effective area S is the projected area of the cylindrical container 20 from the direction of the rotation axis 32 of the stirring blades 30 to the plurality of stirring blades 30. It becomes the area obtained by subtracting the total area of the circle drawn by the tip end of the stirring plate 34 in this case.

In addition, in the high-speed stirring device 10, the efficiency of stirring by rotation of the bottom plate 24 is the transport speed of the sintered raw material 40 transported to the stirring blade 30 by the rotation of the bottom plate 24 Relate to. Since the sintering raw material 40 moves with the rotation of the bottom plate 24, the transport speed at which the sintering raw material 40 is transported to the stirring blade 30 is the circumferential speed v (m/s) of the bottom plate 24 ) Related to. Therefore, the circumferential speed v (m/s) of the bottom plate 24 was taken as one of the indexes showing the efficiency of the stirring in the high-speed stirring device 10. In addition, the circumferential speed of the bottom plate 24 can be calculated by the product of the length m of the circumference of the bottom plate 24 and the rotation speed of the bottom plate 24 (rpm).

In addition, in the high-speed stirring device 10, the efficiency of the stirring by rotation of the stirring blade 30 is the stirring plate 34 which moves at the time when the sintering raw material 40 is stirred in the high-speed stirring device 10 It is related to the amount of movement of the tip of the. Therefore, of the stirring plate 34 which is the product of the time t(s) for the sintering raw material 40 to be stirred in the high-speed stirring device 10 and the peripheral speed u (m/s) which is the speed of the tip of the stirring plate 34 The moving distance "uxt" (m) of the tip end was taken as one of the indexes showing the efficiency of stirring in the high-speed stirring device 10.

In the high-speed stirring device 10, in the following equation (2), which is a product of "L/S", "v", and "u×t", which are indexes showing the efficiency of stirring described above, the stirring of the high-speed stirring device I found what I could evaluate the efficiency of. In addition, the value calculated by the following equation (2) is taken as the stirring speed (m/sec). In addition, although the weir 36 is formed in the high-speed stirring device 10, the movement of the sintered raw material 40 in the cylindrical container 20 does not change significantly with the presence or absence of the weir 36, so the weir With or without (36), the following equation (2) for evaluating the efficiency of stirring of the high-speed stirring device 10 does not change.

[Equation 2]

And it was found that when the stirring speed calculated by the above equation (2) satisfies the following equation (1), a high effect of improving the production rate of sintered ore was obtained in the sintering machine. That is, as shown in FIG. 9 described later, when the stirring speed is 500 m/s or less, the effect of stirring by the stirring blade 30 is not achieved, and coarse pseudo particles containing the sintering raw material 40 can be crushed. I think the cause is not.

[Equation 1]

Moreover, it is preferable to set the stirring speed to 3000 m/s or less. This is because even if the stirring speed is higher than 3000 m/s, there is almost no effect of improving the production rate of sintered ore just by using electric power. This is considered to be because most of the coarse pseudo-particles contained in the sintering raw material 40 were crushed by setting the stirring speed to 3000 m/s.

In addition, in the high-speed stirring device 10, it is also assumed that a plurality of stirring blades 30 are provided, and in that case, the circumferential speed v of the stirring blade 30 is the circumferential speed v of the plurality of stirring blades 30 ) May be a simple average divided by the number of stirring blades 30. Moreover, the effective area S may be a value obtained by subtracting the sum of the areas occupied by the motion of all the stirring blades 30 from the area of the bottom plate 24. In addition, the effective stirring blade length (L) may be the sum of the effective stirring blade length (L) of each stirring blade (30), and v, u, so that the value by formula (2) is 500 m/s or more. By setting t, L, and S, a high effect of improving the production rate of sintered ore can be obtained.

Next, the influence of the content of pulverized iron ore in the raw material for sinter will be described. Using a sintered raw material to which pulverized iron ore was defined as particles having a particle diameter of 0.125 mm or less, and pulverized iron ore composed of hematite ore having a particle diameter of 0.125 mm or less was used, a sample in which the content ratio of the pulverized iron ore contained in the sintered raw material was changed. Was prepared. Here, the raw material for sinter contains 67% by mass of iron ore, 15% by mass of semi-gloss, 5% by mass of carbonaceous material, 11% by mass of limestone as an auxiliary raw material, and 2% by mass of quicklime. In addition, pulverized iron ore was added to each sample, and the fluctuation of the pulverized iron ore content was replaced with a particle diameter of 0.125 mm or more of the iron ore. Then, 7.5% by mass of water was added to the sample and granulated with a drum mixer, and then granulated particles were fired using an iron test pan to produce a sinter cake (sintered product). The manufactured sinter cake was dropped once from a height of 2 m, and the one having a particle diameter of 10 mm or more was set as a property. The product mass (t) was measured with each sample, and the product mass (t) was divided by the sintering time (h) and the cross-sectional area (m2) of the test pan to calculate the sintering production rate (t/(m2×h)). . In addition, the content of pulverized iron ore is a value calculated from the blending amount by measuring the ratio of the iron ore of 0.125 mm or less in advance. In addition, the moisture of a sample is a limit with respect to the amount of the raw material for sintering, and is a value calculated from the raw material and the added moisture on a drying basis.

7 is a graph showing the relationship between the content of pulverized iron ore having a particle diameter of 0.125 mm or less and a sintered production rate. As can be seen from the graph, when the ratio of the pulverized iron ore having a particle diameter of 0.125 mm or less contained in the raw material for sinter exceeds 10% by mass, the sintering production rate is rapidly decreasing. From this, it is considered that when the proportion of the pulverized iron ore exceeds 10% by mass, coarse pseudo-particles with weak bonding strength are formed, and as a result, the sintering production rate has rapidly decreased. Moreover, when the proportion of pulverized iron ore exceeds 50% by mass, granulation in a drum mixer becomes difficult. For this reason, the condition under which coarse pseudo-particles are formed in the raw material for sintering can be said to be the case where the finely divided iron ore of 0.125 mm or less is contained within the range of 10 to 50 mass%. In addition, since the sintered raw material having a particle diameter of 0.125 mm or less exhibited a behavior in which the adhesion between particles was increased and the granularity of the sintered raw material was different in the powder to which water was added, the critical value of the particle diameter of the pulverized iron ore Was set to 0.125 mm.

Next, the influence of the concentration of Al ₂ O _{3 in} the raw material for sinter will be described. When the Al ₂ O ₃ concentration in the sintering raw material 40 is high, there is a problem that the viscosity of the melt, which is a factor of improving the strength of the sintered ore during manufacture of the sintered ore, increases. In addition, ores containing a large amount of Al ₂ O ₃ are classified as clay-based ores that tend to be aggregated. Therefore, when a raw material for sintering with a high Al ₂ O ₃ ratio is used, ore containing a large amount of Al ₂ O ₃ is aggregated, thereby increasing the viscosity of the melt generated during sintering, and the melt is charged during the production of the sintered ore. It is not dispersed in the layer, and the intensity of the sintered ore decreases.

Therefore, when the Al ₂ O ₃ concentration of the sintering raw material 40 is high, the sintering raw material 40 is subjected to agitation treatment using the high-speed stirring device 10 to disperse iron ore containing a large amount of Al ₂ O ₃ . It is desirable. Thereby, the increase in viscosity of the melt due to Al ₂ O ₃ during sintering is suppressed, and since the melt generated during production of the sintered ore can be dispersed in the sintering raw material 40, the strength of the sintered ore is improved. In addition, although the details will be described later, the effect of improving the strength of the sintered ore by the stirring treatment of the high-speed stirring device 10 increases when the concentration of Al ₂ O ₃ in the sintered ore sintered by the sintering machine is 1.6 mass% or more.

Moreover, in the case of agitation treatment using the high-speed stirring device 10, at least any one of a binder, carbonaceous material, and limestone contained in the sintering raw material 40 may be contained and agitated. Limestone is aggregated by the addition of moisture. When limestone aggregates, it becomes difficult to dissolve in the melt, and the total amount of melt decreases. Thereby, the strength of the sintered ore decreases. For this reason, by stirring the limestone together with the sintering raw material 40 using the high-speed stirring device 10, it is possible to disperse limestone which is likely to be aggregated in the sintered raw material 40 containing moisture. By dispersing the limestone, the limestone becomes easy to dissolve in the melt, and the total melt amount increases. By increasing the total amount of melt, since the strength of the sintered ore is improved, as a result, the yield of the sintered ore is increased, and the productivity of the sintered ore is improved. Thus, by the stirring treatment with the high-speed stirring device 10, the productivity of the sintered ore can be improved compared to the case where the stirring treatment is not performed.

In addition, by adding a binder originally added before granulating with a drum mixer to the sintering raw material 40 before performing the stirring treatment, and stirring using a high-speed stirring device 10, a binder that is easily agglomerated in the sintering raw material Can be dispersed in the raw material for sintering 40. Since the drum mixer cures the binder to granulate particles, if the binder can be dispersed, variations in the bonding strength of the granulated particles can be suppressed. Thereby, it is possible to suppress particles of weak bonding strength from being granulated by the drum mixer.

The granulated particles having weak bonding strength are destroyed by impact when the granulated particles are supplied to the pallet of the sintering machine, and fine powder is generated by the fracture. Due to the fine powder generated by the fracture, the air permeability of the charged layer is inhibited, and the productivity of the sintered ore decreases. By stirring the binder together with the sintering raw material 40 using a high-speed stirring device 10 and dispersing the binder in the sintering raw material 40, it is possible to suppress granulation of particles with weak bonding strength, The productivity of the sintered ore can be improved compared to the case where the stirring treatment is not performed by the stirring device 10.

Moreover, the carbon material can be dispersed in the raw material for sintering by stirring the carbon material using the high-speed stirring device 10. When the sintering raw material is sintered in a state where the carbon material is not dispersed in the sintered raw material and is contained unevenly, baking unevenness occurs. Baking unevenness is a cause of insufficient sintering and lowering the strength of the sintered ore. For this reason, by stirring the carbon material together with the sintering raw material 40 using a high-speed stirring device 10 to disperse the carbon material, the occurrence of the baking unevenness can be suppressed. The productivity of the sintered ore can be improved compared to the case where it is not treated.

Next, the content of Al ₂ O ₃ and the timing of adding limestone will be described. Samples in which the content of Al ₂ O ₃ and the time of lime addition were changed were prepared, and an experiment was conducted to confirm the effect of improving the production rate of the sintered ore using each sample. Table 1 shows the conditions corresponding to each experimental example. In addition, the term "before stirring" when the limestone is added means that the raw material for sinter contains limestone before the stirring treatment is performed using the high-speed stirring device 10. In addition, the term "after stirring" when the limestone addition timing is performed means that the sintering raw material contains limestone after stirring treatment using the high-speed stirring device 10.

For these samples, using a high-speed stirring device 10 having a diameter of the stirring blade 30 of 0.35 m and a diameter of the cylindrical container 20 of 0.75 m, the rotational speed of the stirring blade 30 was 500 rpm, and the bottom plate The agitation treatment was carried out by setting the rotation speed of (24) to 28 rpm. In addition, the sintering raw material 40 in each sample was adjusted to contain 15 mass% of pulverized iron ore having a particle diameter of 0.125 mm or less. Here, the raw material for sinter contains 67% by mass of iron ore, 15% by mass of semi-gloss, 5% by mass of carbonaceous material, 11% by mass of limestone as an auxiliary raw material, and 2% by mass of quicklime. Moreover, the water content at the time of stirring by the high-speed stirring device 10 was 5.5 mass %. Moreover, using a drum mixer, water was added so that the water content might become 7.5 mass %, and granulation was performed for 300 seconds. Then, the granulated granulated particles were sintered using an iron test pan to prepare a sinter cake, and the sintered production rate was calculated. Further, not only the stirring treatment was performed, but also the granulated particles granulated under the same conditions as other conditions were fired using the same iron test pan to produce sinter cake, and the sintered production rate was calculated.

8 is a graph showing the relationship between Experimental Examples 1 to 4 and the effect of improving the production rate. In addition, the production rate improvement effect was calculated by taking the difference between the sintered production rate when the stirring treatment was performed by the high-speed stirring device 10 and the sintered production rate when the stirring treatment was not performed by the high-speed stirring device 10 . As a result, compared with Experimental Example _{3 where} the proportion of Al ₂ O ₃ was lower than 1.6% by mass, it was found that Experimental Examples 1 and 2 in which the proportion of Al ₂ O ₃ was 1.6% by mass or more had a greater effect of improving the production rate. I can. From the above results, when the concentration of Al ₂ O ₃ is 1.6 mass% or more, it has become clear that the effect of the present invention becomes larger.

In addition, compared to the time of adding limestone, it was after the stirring treatment with the high-speed stirring device 10, and before the stirring treatment with the high-speed stirring device 10 compared to Experimental Example 4 in which limestone was added before assembling with a drum mixer, It can be seen that the added Experimental Example 2 has a large effect of improving the sintering production rate. By stirring the raw material 40 containing limestone with the high-speed stirring device 10, it is added to Al ₂ O ₃ to increase the viscosity of the melt, and the limestone for increasing the amount of the melt can be dispersed in the raw material 40 for sintering. have. Thereby, since it is possible to increase the melt by reducing unreacted limestone, the strength of the sintered ore is further improved, and as a result, it is considered that the sintered production rate is further improved.

From the above results, in the method for producing a sintered ore, even if it is a sintered raw material containing 15% by mass of pulverized iron ore having a particle diameter of 0.125 mm or less and a concentration of Al ₂ O ₃ of 1.6% by mass or more in the sintered ore, the high-speed stirring device 10 It was found that the productivity of the sintered ore could be further improved by granulating with a drum mixer after the stirring treatment to produce a sintered ore.

In addition, in the present embodiment, quicklime (CaO) was used as the binder, but slaked lime (Ca(OH) ₂ ), which is a binder that increases the granularity in a drum mixer, a thick organic binder, and an inorganic binder may be used. . Since quicklime is inexpensive, a sintered ore can be manufactured inexpensively by using quicklime as a binder.

As described above, the present invention has been described with reference to the embodiments, but the present invention is not limited at all to the configuration described in the above embodiments, and other embodiments and modifications conceivable within the scope of matters described in the claims. It also includes examples.

Example

The sintered raw material 40 containing pulverized iron ore was subjected to agitation treatment using a high-speed stirring device 10, and then the effect of improving the productivity of the sintered ore was confirmed using granulated particles granulated using a drum mixer. As the sintering raw material 40, a sintered raw material containing 15 mass% of pulverized iron ore having a particle diameter of 0.125 mm or less and an iron ore raw material having an Al ₂ O ₃ concentration of 1.6 mass% in the sintered ore was used. Here, the raw material for sinter contains 67% by mass of iron ore, 15% by mass of semi-gloss, 5% by mass of carbonaceous material, 11% by mass of limestone as an auxiliary raw material, and 2% by mass of quicklime. Moreover, the water content at the time of stirring by the high-speed stirring device 10 was 5.5 mass %. Further, water was added so that the moisture content was 7.5% by mass, granulated using a drum mixer for 300 seconds, and then sintered to produce a sintered ore, and the effect of improving the sintered production rate was calculated. In Table 2 below, the stirring conditions of the stirring blade 30 of the high-speed stirring device 10 in the present invention Examples 1 to 7 and Comparative Examples 1 and 2, the rotation conditions of the bottom plate 24, the stirring time, and the effective blade It shows the effect of improving length, effective area, stirring speed and production rate.

9 is a graph showing the relationship between the stirring speed and the effect of improving the sintering production rate. 9 is a graph in which Invention Examples 1 to 7 and Comparative Examples 1 and 2 in Table 2 are plotted, respectively, in the case where the vertical axis is used as the production rate improvement effect and the horizontal axis is the stirring speed. From Fig. 9, it was found that a high effect of improving the production rate of sintered ore was obtained by making the stirring speed higher than 500 m/s. On the other hand, it was found that even if the stirring speed was higher than 3000 m/s, the effect of improving the production rate of the sintered ore did not change. Further, from Fig. 9, it is understood that the stirring speed is more preferably 700 m/s or more, and even more preferably 1300 m/s or more.

Subsequently, in the conditions of Table 2, in order to confirm whether the coarse pseudo-particles were pulverized by the high-speed stirring device 10, the relationship between the average particle diameter after stirring and the effect of improving the production rate was confirmed. Here, as for the average particle diameter, 1 kg of a powder sample after agitation treatment is collected, and after drying, the powder sample is sieved in the order of wide scale intervals using a sieve having a scale interval of 0.25, 0.5, 1, 2.8, 4.75, and 8 mm. Was hit, the mass ratio of each particle size was measured, and the weighted average of the particle diameters using the mass ratio was calculated.

10 is a graph showing the relationship between the average particle diameter after the stirring treatment and the effect of improving the sintering production rate. It can be seen from FIG. 10 that the effect of improving the production rate of the sintered ore is large when the average particle diameter after the stirring treatment by the high-speed stirring device 10 is 3 mm or less. That is, the sintering raw material 40 is stirred with the high-speed stirring device 10, coarse pseudo-particles in the sintered raw material 40 are pulverized, and the average particle diameter of the sintered raw material 40 is set to 3 mm or less. The effect of improving the production rate could be increased. In addition, from FIG. 10, it is understood that the average particle diameter after the stirring treatment with the high-speed stirring device 10 is more preferably 2.5 mm or less, and even more preferably 2 mm or less.

Subsequently, the water content at the time of stirring that the average particle diameter after the stirring treatment was performed using the high-speed stirring device 10 was 3 mm or less was measured. The whole amount of the raw material for sintering 40 was charged into the high-speed stirring device 10, followed by agitation treatment, and the average particle diameter after the stirring treatment was measured. As the raw material for sintering 40, the raw material for sintering 40 having a pulverized iron ore ratio of 15% by mass, a nuclear particle ratio of 55% by mass, and an Al ₂ O ₃ ratio of 1.6% by mass was used. Here, the raw material for sinter contains 67% by mass of iron ore, 15% by mass of semi-gloss, 5% by mass of carbonaceous material, 11% by mass of limestone as an auxiliary raw material, and 2% by mass of quicklime. The diameter of the cylindrical container 20 in the high-speed stirring device 10 is 0.75 m, and the diameter of the stirring blade 30 is 0.35 m. Moreover, the rotation speed of the bottom plate 24 in the cylindrical container 20 is 28 rpm, and the rotation speed of the stirring blade 30 is 500 rpm. A sintering raw material 40 having a different moisture content was prepared, agitation treatment was performed under the above conditions, and the average particle diameter after the stirring treatment in each moisture content was measured.

11 is a diagram showing a relationship between moisture during a stirring treatment and average particles after a stirring treatment. It can be seen from FIG. 11 that the average particle diameter after the stirring treatment becomes 3 mm or less by making the moisture content at the time of stirring 7% by mass or less, and the effect of improving the production rate of the sintered ore by performing the stirring treatment increases. In addition, from Fig. 11, it can be seen that the moisture content during stirring is more preferably 6% by mass or less, and more preferably 4% by mass or less during stirring.

10: high speed stirring device
20: cylindrical container
22: cylinder
24: bottom plate
30: stirring blade
32: rotating shaft
34: stirring plate
36: dam
40: raw material for sinter
50: won
52: area

Claims (10)

As a method for producing a sintered ore,
With a high-speed stirring device having a rotating cylindrical container and a stirring blade rotating in the cylindrical container, the raw material for sinter is stirred so as to satisfy the following equation (1),
The sintered raw material after the stirring treatment is granulated using a granulating device,
A method for producing a sintered ore in which the granulated raw material for sintering is sintered using a sintering machine to produce a sintered ore.
[Equation 1]

However, in the above equation (1),
v: peripheral speed of the bottom plate of the cylindrical container (m/s),
u: peripheral speed of the tip of the stirring blade (m/s),
t: time (s) for the sintering raw material to be stirred by a high-speed stirring device,
L: the length of the circumference drawn by the tip of the stirring blade (m),
S: It is the area (m 2) obtained by subtracting the area of the circle drawn by the tip of the stirring blade from the projected area of the cylindrical container projected from the rotation axis direction of the stirring blade. The method of claim 1,
The sintered raw material contains 10 to 50 mass% of pulverized iron ore having a particle diameter of 0.125 mm or less, and the Al ₂ O ₃ concentration of the sintered ore obtained by sintering the sintered raw material with the sintering machine is 1.6 mass% or more. The method according to claim 1 or 2,
The sintering raw material is a method for producing a sintered ore further containing a binder. The method of claim 3,
The binder is a method of manufacturing a sintered ore, which is quicklime. The method according to claim 1 or 2,
The method for producing a sintered ore having an average particle diameter of the raw material for sintering after stirring by the high-speed stirring device is 3 mm or less. The method of claim 3,
The method for producing a sintered ore having an average particle diameter of the raw material for sintering after stirring by the high-speed stirring device is 3 mm or less. The method of claim 4,
The method for producing a sintered ore having an average particle diameter of the raw material for sintering after stirring by the high-speed stirring device is 3 mm or less. The method of claim 5,
The method for producing a sintered ore, wherein the raw material for sintering before being subjected to agitation treatment with the high-speed stirring device contains 7% by mass or less of moisture. The method of claim 6,
The method for producing a sintered ore, wherein the raw material for sintering before being subjected to agitation treatment with the high-speed stirring device contains 7% by mass or less of moisture. The method of claim 7,
The method for producing a sintered ore, wherein the raw material for sintering before being subjected to agitation treatment with the high-speed stirring device contains 7% by mass or less of moisture.

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