JP4568243B2 - Method of kneading fine powder material - Google Patents

Description

The present invention relates to a method for kneading a fine powder material that is suitable for granulation of an iron ore raw material mainly composed of fine powder and that can produce a granulated product having a target particle size distribution.

Conventionally, high-quality iron ore raw materials such as hematite have been used as iron ore raw materials (also referred to as iron making raw materials) to be supplied to a sintering machine. There is a tendency for the amount of iron ore raw materials containing a lot of fine powder to increase.
For this reason, in the operation of the sintering machine, it is necessary to make full use of these iron ore raw materials without problems, and a new granulation strengthening technique for the iron ore raw materials is required. As such a granulation method, for example, Patent Document 1 and Patent Document 2 disclose a method using a high-speed agitation type mixer, thereby achieving granulation strengthening of an inferior iron ore raw material.

Japanese Patent No. 2790008 Japanese Patent No. 2953308

However, these prior arts are granulated in a state in which iron ore raw materials ranging from a coarse particle having a particle size distribution of several mm to a fine powder having a particle size of 250 μm are mixed. It is intended for a granulation method in which fine powder is adhered to the surface.
For this reason, when the conventional technology is used for iron ore raw materials in which the proportion of fine powder will further increase in the future, the adhesion thickness of fine powder on the surface of coarse particles that become core particles becomes excessive, for example, granulation due to deterioration in combustibility of fuel particles Decrease in sinterability of objects occurs. In addition, since the number of coarse particles serving as core particles is extremely insufficient with respect to the fine powder, there is a problem that granulation is incomplete in the prior art.
In this way, in the future, it will be necessary to granulate iron ore raw materials containing a large amount of fine powder, or to separate and granulate only iron fines from iron ore raw materials. There is a need to establish a technology for automatic granulation.

The present invention has been made in view of such circumstances, and is suitable for granulation of iron ore raw materials mainly composed of fine powder, and can produce a granulated product having a target particle size distribution, and its yield (yield). It is an object of the present invention to provide a method for kneading a fine powder raw material that can be improved over conventional methods.

In order to obtain a granulated product having a particle size distribution of 3 mm or more and 10 mm or less in a yield of 60% by mass or more, the kneading method of the fine powder raw material according to the present invention that meets the above-mentioned object includes 60% by mass or more of particles having a particle size of 250 μm or less The iron ore material is kneaded by a kneader having a cylindrical container containing the iron ore material and a stirring blade that rotates in the container to knead the iron ore material, and the average particle size is 3 mm or more and 7 mm or less. The kneaded material is kneaded, and the kneaded material is put into a drum mixer to produce the granulated material. The kneaded material is kneaded, and the inner diameter of the container is D (m), and the peripheral speed of the stirring blade is u. (M / s) and when the gravitational acceleration of the kneaded product is g (m / s ² ), the stirring acceleration (u ² / D + g) of the stirring blade is 20 m / s ² or more and 70 m / s ² or less. Set within the range .

In the method for kneading the fine powder raw material according to the present invention, the kneading time of the iron ore raw material is preferably 10 seconds or more, and the water content of the kneaded material after kneading is preferably in the range of 7% by mass to 12% by mass. .

The kneading method of the fine powder raw material according to claim 1 and 2 produces a kneaded product having an average particle size within a predetermined range from an iron ore raw material containing a large amount of fine powder. A large kneaded product is used as a core, and an iron ore raw material is adhered to the surface thereof to produce a granulated product having a target particle size, and the yield of the granulated product having a target particle size distribution can be improved. Thereby, since it can be made an appropriate amount, without making the adhesion thickness of the iron ore raw material adhering to the surface of a kneaded material excessive, the fall of the sinterability of the granulated material by the combustibility deterioration of a fuel particle can be prevented, for example. Therefore, when manufacturing the sintered ore by charging the manufactured granulated material into the sintering machine, it is possible to manufacture a sintered ore with good quality and high productivity without inhibiting the air permeability of the sintering machine.

In particular, the method for kneading the fine powder raw material according to claim 1 uses a kneader equipped with stirring blades for the production of the kneaded product, and sets the stirring acceleration of the stirring blades within an appropriate range. It is possible to suppress the coarsening due to coalescence of the kneaded materials due to insufficient stirring without giving force and destroying the kneaded material. As a result, the kneaded product can be grown to a target particle size, and as a result, the yield of the granulated product having the target particle size distribution can be improved.

In the method for kneading the fine powder raw material according to claim 2, since the kneading time of the iron ore raw material is set within an appropriate range, the particle interval of each iron ore raw material constituting the kneaded product is reduced (increasing the density), By exuding moisture from the mixture, the required moisture content of the kneaded product can be reduced, and the influence of fluctuations in residence time during the kneading of the iron ore raw material can be reduced. At this time, by setting the moisture content of the kneaded material after kneading to an appropriate range, the amount of moisture oozing out to the surface of the kneaded material that becomes the core during kneading can be controlled, and for example iron ore adhering via moisture The amount of stone raw material can be controlled. As a result, the kneaded product can be grown to a target particle size, and as a result, the yield of the granulated product having the target particle size distribution can be improved.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
Here, FIG. 1 is an explanatory diagram of a method for kneading a fine powder raw material according to an embodiment of the present invention, and FIG. 2 is a relationship between the average particle size of the kneaded product and the yield of the granulated product having a target particle size distribution. FIG. 3 is an explanatory diagram of a mechanism for determining the particle size of the kneaded product, and FIG. 4 is an explanatory diagram showing the relationship between the stirring acceleration of the stirring blade and the moisture content of the kneaded product and the average particle size of the kneaded product. FIG. 5 is an explanatory diagram showing the relationship between the water content of the kneaded material and the adhesion of the iron ore material, and FIG. 6 shows the relationship between the stirring energy input to the iron ore material and the adhesion of the iron ore material. FIG. 7 is an explanatory diagram comparing the relationship between the kneading time by the kneader and the necessary water content of the kneaded material for obtaining the target average particle size.

As shown in FIG. 1, in the method for kneading fine powder raw material according to an embodiment of the present invention, an iron ore raw material (hereinafter also simply referred to as raw material) containing 60% by mass or more of particles having a particle size of 250 μm or less is kneaded. 10 to produce a kneaded product having an average particle size of 3 mm to 7 mm, and the kneaded product is put into a drum mixer (also referred to as a granulator) 11 to produce a granulated product. This will be described in detail below.

First, an iron ore raw material is put into the kneading machine 10, and water and a binder are further added, and these are kneaded.
Here, the iron ore raw material contains 60% by mass or more of particles having a particle size of 250 μm or less. For example, a raw material containing a large amount of fine powder, a raw material adjusted to the above-described configuration by screening, and only fine powder are separated by screening. Raw materials, and further pulverized raw materials can be used. This iron ore raw material is, for example, one or more of limonite (Fe ₂ O ₃ .nH ₂ O), magnetite (Fe ₃ O ₄ ), and hematite (Fe ₂ O ₃ ). Examples of limonite include maramamba ore (local brand: West Angelus), pisolite ore (local brand: Yandhi, Loeb River), and high phosphorus block man ore.

As the iron ore raw material, the raw material containing 60% by mass or more of particles having a particle size of more than 0 μm and not more than 250 μm is targeted when the raw material having such a structure is granulated by a conventional method, as described above. This is because the sinterability of the granulated product is deteriorated or the granulation becomes incomplete, and even if granulation is possible, the required strength cannot be obtained.
Therefore, in this embodiment, the iron ore containing particles having a particle size of 250 μm or less, preferably 220 μm or less, more preferably 200 μm or less, 60 mass% or more, preferably 70 mass% or more, more preferably 80 mass% or more. Stone raw materials are to be kneaded. The reason why the upper limit of the amount of fine powder is not specified is that all fine powder may be used.
Thus, in this Embodiment, since the iron ore raw material of a fine powder is made into object, a fine iron-containing raw material can also be further included in an iron ore raw material. As this iron-containing raw material, for example, any one or two of dust (kneaded dust or dust dust) and pellet raw material (also referred to as pellet feed) can be used. The particle size of the dust is about 100 μm or less, and the particle size of the pellet raw material is about 250 μm or less.

Since the binder contributes to improving the strength of the granulated product, an inorganic binder such as quick lime or limestone that has been conventionally used can be used. In addition, as the binder, for example, any one of an organic binder containing pulp waste liquid or corn starch (aqueous solution or colloidal form) and a dispersing agent (including an aqueous solution or colloid added with a dispersing agent) that promotes solid crosslinking Although 1 or 2 is preferably used, it may be used in combination with an inorganic binder.
In addition, the addition amount of a binder may be about 1 mass% or less on the outside with respect to the iron ore raw material amount.

Next, the kneader 10 for kneading iron ore raw materials will be described.
In order to perform the granulation of the raw material with high productivity, it is necessary to mix water and a binder in the drum mixer into which the raw material is charged and to mix them uniformly. At this time, it is common practice to install the kneader in front of the drum mixer.
However, even if the raw materials are simply kneaded using a kneader, if this kneaded product is put into a drum mixer and manufactured, as shown in FIG. 2, the target particle size distribution suitable for supply to the sintering machine A granulated product of 3 mm or more and 10 mm or less cannot be obtained with a high yield (60% by mass or more in the present embodiment). For this reason, in order to obtain a granulated product having a target particle size distribution with a high yield, it is necessary to ensure the average particle size of the kneaded material within an appropriate range of 3 mm to 7 mm.
Therefore, in the present embodiment, in order to bring the average particle size of the kneaded material into an appropriate range, as the kneader 10, a cylindrical container 12 for containing the iron ore raw material and the iron ore raw material rotated in the container 12 are kneaded. An apparatus having a plate-like stirring blade 13 is used.

As for the average particle size of the kneaded product, when the lower limit is less than 3 mm, the size of the kneaded product necessary for producing the granulated product with high productivity when the drum mixer is subsequently granulated is set. Since it is not satisfactory and granulation cannot proceed sufficiently, the proportion of undesired fine particles increases. On the other hand, when the upper limit of the average particle size of the kneaded product exceeds 7 mm, excessive granulation is performed by the drum mixer, and the proportion of undesired coarse particles increases.
From the above, the average particle size of the kneaded product was defined as 3 mm or more and 7 mm or less. However, in order to obtain the yield of the granulated product having the target particle size distribution more stably, the lower limit value of the average particle size of the kneaded product is set to 3 It is preferable that the upper limit value is set to 0.5 mm, further 4 mm, and the upper limit value to 6 mm, and more preferably 5.5 mm.
Here, the average particle diameter of the kneaded product is 10.0, 8.0, 6.7, 4.75, 2.8, 2.0, and 1. Sieving with each 0 mm sieve to determine the weight ratio of each particle size section, the representative diameter of each particle size section is 12.0, 9.0, 7.35, 5.73, 3.78, 2.4, It was set to 1.5 and 0.7 mm, and this was obtained by weighted averaging at a weight ratio.

Next, the selection of a specific kneader having the above-described configuration and the results of studying the operating conditions of the kneader will be described.
As a result of conducting kneading experiments using various kneaders, the present inventors have found that the influence of the kneader configuration and the water content of the kneaded material (hereinafter also referred to as the moisture value) on the kneaded material properties is large. . As a result of examining the mechanism for explaining these systematically, it was found that the average particle size of the kneaded product is determined by the balance between the stirring force and the adhesion force of the raw materials.
When kneading with a kneader, the raw materials are repeatedly coalesced and separated by stirring the raw materials. Ultimately, the inertial force due to stirring acting on the volume of the raw materials acts as an action for separating the combined raw materials, and the raw materials It is considered that the adhesive force acting on the surface of the material works as an action to unite the dispersed raw materials.

FIG. 3 showing this phenomenon image illustrates the coalescence and separation behavior of the reference raw material A and the relatively large raw material B and small raw material C with respect to the raw material A. A thin arrow indicates separation by inertia force, and a thick arrow indicates coalescence by adhesion force.
When the size of the raw material A is used as a reference, since the raw material B is relatively large, the ratio of the volume to the surface area is large, and the body force (inertial force) wins and separates from the raw material A. On the other hand, since the raw material C is small, the ratio of the surface area to the volume is large, and the adhesive force is won and the state of adhering to the raw material A is maintained.
As a result of such separation and coalescence being repeated between the raw materials A to C, it is considered that the finally obtained kneaded product converges to a certain particle size from the balance of inertia force and adhesion force.

From this, the inner diameter of the container of the kneading machine is D (m), the peripheral speed of the stirring blade in the container is u (m / s), the gravitational acceleration of the kneaded material is g (m / s ² ), and the density of the kneaded material. Is ρ (kg / m ³ ), the average particle size of the kneaded product is d (m), and the iron ore raw material adhesion force is F (kg · m / s ² / m ² ). The balance is expressed by the following equation. The stirring acceleration of the stirring blade (hereinafter also simply referred to as stirring acceleration) is expressed as (u ² / D + g).
d ³ × ρ × (u ² / D + g) = d ² × F
Thereby, the average particle diameter of a kneaded material is represented by the following formula | equation.
d = F / ρ / (u ² / D + g) (1)

Here, in order to examine factors affecting the stirring force, the stirring acceleration (u ² / D + g) of the stirring blades of various kneaders (pug mill, pin mixer, and readyge mixer) and kneading obtained by various kneaders This will be described with reference to FIG. 4 showing the relationship with the average particle size of the product. In FIG. 4, the theoretical line (model calculation value under a constant stirring energy) obtained by using the above formula (1) and separately for the moisture content of the kneaded product (hereinafter also simply referred to as the moisture value) is shown together. ing.
As shown in FIG. 4, the average particle size of the kneaded material is inversely proportional to the stirring acceleration of the stirring blades, and if the influence of the moisture value of the kneaded material is also taken into consideration, the target average particle size of the kneaded material is stably secured. In order to achieve this, the stirring acceleration must be regulated to 20 (m / s ² ) or more and 70 (m / s ² ) or less. This is because when the stirring acceleration is less than 20 (m / s ² ), the adhesion between the raw materials is excellent, the raw materials are united and grow, so that the kneaded material becomes coarse, and the influence of the fluctuation of the moisture value of the kneaded material is also affected. On the other hand, when the stirring acceleration exceeds 70 (m / s ² ), the stirring force is too strong and the kneaded product is destroyed, so that the average particle size of the kneaded product tends to be too small. It is to become.

For this reason, the stirring acceleration of the stirring blade is defined as 20 (m / s ² ) or more and 70 (m / s ² ) or less as a range to ensure the target average particle size of the kneaded material, but preferably 20 (m / s ^2). ) To 50 (m / s ² ) or less.
Based on the above examination results, for example, a Redige mixer or a pin mixer that has been conventionally used can be used as a kneader satisfying such a stirring acceleration. An Eirich mixer, which is a high-speed stirring mixer, can also be used by adjusting the agitator rotation speed to a low speed.

In the Redige mixer and the pin mixer, the rotating shafts of the stirring blades are arranged in parallel to the ground, and the kneaded product is kneaded while moving up and down, so the influence of the gravitational acceleration g of the kneaded product is large. For this reason, it is good to ensure the stirring acceleration of a stirring blade in the said range which considered the gravity acceleration g.
However, when the Eirich mixer is used, the rotating shaft of the stirring blade is arranged in the vertical direction with respect to the ground, and the kneaded product is kneaded in the horizontal direction. Get smaller. Accordingly, in this case, while taking into account the agitator rotation speed that affects the gravitational acceleration g of the kneaded product, the range obtained by subtracting the stirring acceleration of the stirring blade by 10 (m / s ² ) at the maximum, that is, 10 (M / s ² ) to 60 (m / s ² ), preferably 10 (m / s ² ) to 40 (m / s ² ).

Next, the results of studying factors affecting the adhesion force of raw materials will be described with reference to FIGS.
The adhesion force of the raw material is expressed by the following formula based on the formula (1).
F = d × ρ × (u ² / D + g) (2)
FIG. 5 is a result of plotting the adhesion force of the raw material obtained by the equation (2) with respect to the moisture value of the kneaded product for the various kneaders described above. The adhesion force of the raw material is proportional to the moisture value. However, there were cases where the same moisture value was different. Further, as a result of further investigation on this relationship, it was found that the greater the stirring energy, the greater the adhesion of the raw material.
FIG. 6 is a result of plotting the adhesion force of the raw material obtained by the above equation (2) against stirring energy (u ² / D + g) × u × t (t is kneading time: s). It was found that the adhesion force of the raw material increases as the energy increases, while the adhesion force of the raw material gradually becomes stable (the increase amount becomes smaller) above a certain stirring energy.

FIG. 7 shows the result of calculating the operating range when a Redige mixer is used as the kneader from the relationship shown in FIGS. FIG. 7 shows the result of calculating an appropriate moisture value range for securing the average particle size of the kneaded material (hereinafter also simply referred to as the kneaded material particle size) to 3 mm to 7 mm with respect to the kneading time. 7, the moisture value at which the kneaded product obtains an average particle diameter of 3 mm is indicated by a dotted line, and the moisture value at which an average particle diameter of 7 mm is obtained is indicated by a solid line at each agitation acceleration of 7, ie, 40, 90 and 90 (m / s ² ). In the figure, an appropriate range of moisture value (shaded part) is shown in between.
As is clear from FIG. 7, in the range where the kneading time is short, the kneaded product has a large change in the moisture value necessary for obtaining the above average particle size, and the kneaded product particle size varies greatly with respect to the variation in the moisture value. Conceivable. In addition, by increasing the kneading time to some extent, the moisture value of the kneaded product can be reduced, and the drying load after the granulated product produced thereafter can be reduced.
From the above, it was defined that the kneading time was secured for 10 seconds or more. As is clear from FIG. 7, the longer kneading time does not significantly affect the fluctuation of the moisture value, so the upper limit value is not specified, but considering productivity, it is 5 minutes or less, preferably 3 minutes or less.

When the stirring acceleration of the stirring blade is as small as about 10 (m / s ² ), the target moisture value range is narrow, and when the moisture value fluctuates, the kneaded product particle size may deviate from the target range. Concerned. On the other hand, when the stirring acceleration of the stirring blade is as large as about 90 (m / s ² ), the moisture value must be excessively increased to 12% by mass or more, which increases the drying load after granulation. .
Here, when the stirring acceleration of the stirring blade is secured to about 40 (m / s ² ) within the above-described appropriate range, the moisture value of the kneaded product becomes 8% by mass or more and 10% by mass or less. Workability at the time becomes better.
From these facts, when the water content of the kneaded material is less than 7% by mass, the water range to be controlled is narrowed as a result, which does not hold industrially. On the other hand, when the water content exceeds 12% by mass, As a result, a large load was applied, which was not preferable.

Therefore, although the range of the moisture value of the kneaded material is defined as 7% by mass or more and 12% by mass, the lower limit value is preferably 8% by mass and the upper limit value is 11% by mass.
Based on the above results, in the kneader 10 described above, either 1 or 2 of the stirring acceleration of the stirring blade 13 and the moisture content (including the kneading time) of the kneaded material after kneading is set, and the average particle size is 3 mm. A kneaded material of 7 mm or less is produced.
And by putting this kneaded material into the drum mixer 11, as shown in FIG. 2, the granulated material with the yield of the granulated material with a particle size distribution of 3 mm or more and 10 mm or less can be manufactured, for example, 60 mass% or more. The produced granulated product is sieved by a sieve sorter as necessary, further dried by a dryer 14, and supplied to a sintering machine (not shown).

Next, examples carried out for confirming the effects of the present invention will be described.
Here, iron ore powder (iron ore raw material) containing 80% by mass of particles having a particle size of 250 μm or less is placed in a readyge mixer (inner diameter of container: 2000 mm), and water and an organic binder are added thereto and kneaded. The average particle size of the obtained kneaded material was examined. Here, the average particle size of the kneaded product was measured for each time by performing kneading of iron ore powder five times for each example and comparative example, and the obtained particle size distribution is shown in the following tables, respectively. It was. In addition, the case where the number of times that the average particle size of the kneaded material entered the range of 3 mm or more and 7 mm or less was 5 was evaluated as ◯, the case of 2 to 4 times as Δ, or the case where it did not enter as ×.
This kneaded product was put into a drum mixer to produce a granulated product, and the yield of the granulated product having a particle size of 3 mm or more and 10 mm or less was also investigated. In the following examination, the kneading time by the Redige mixer was fixed to 120 seconds.

First, the result of examining the influence of the stirring acceleration of the stirring blade will be described.
Here, Examples 1 to 3 are the results of setting the stirring acceleration of the stirring blades to an appropriate range of 20 m / s ² or more and 70 m / s ² or less, and Comparative Examples 1 and 2 are outside the appropriate range. This is the result of setting. The moisture value of the kneaded product was set to 9.5% by mass.

As is apparent from Table 1, as the stirring acceleration increased, the kneaded material tended to be broken and its average particle size tended to be small.
Here, in Example 2, since the stirring acceleration was the best value in the appropriate range, the average particle size of the kneaded product was judged as ◯, and as a result, the yield of the granulated product of the appropriate particle size was also 60% by mass or more. Was achieved. In Examples 1 and 3, since the stirring acceleration corresponded to the lower limit value and the upper limit value of the appropriate range, the average particle size of the kneaded material was Δ. For this reason, although the yield of the granulated material of an appropriate particle size did not reach Example 2, the favorable result was obtained.
On the other hand, when the stirring acceleration is smaller than the lower limit value of the appropriate range as in Comparative Example 1, the kneaded material is coarsened. On the other hand, when the stirring acceleration is higher than the upper limit value of the appropriate range as in Comparative Example 2, kneading is performed. The product was destroyed, and a kneaded product having an average particle size within an appropriate range could not be obtained (judgment: x). For this reason, the yield of the granulated product with an appropriate particle size also deteriorated.
From the above, the stirring acceleration of the stirring blade is set to 20 m / s ² or more and 70 m / s ² or less, and the average particle size of the kneaded product is set within an appropriate range, thereby increasing the yield of the granulated product with the appropriate particle size. I was able to confirm that

Next, the result of examining the moisture value of the kneaded material when the stirring acceleration of the stirring blade is set to 20 m / s ² which is the lower limit value of the appropriate range will be described.
Here, Examples 1 and 4 are the results of setting the moisture value of the kneaded material to an appropriate range of 7% by mass or more and 12% by mass or less, and Comparative Example 3 is set to be less than the lower limit value of the appropriate range. It is the result.

As is clear from Table 2, there was a tendency for the kneaded product to become coarser as the moisture value of the kneaded product increased. For this reason, as shown in Example 4, by setting the moisture value of the kneaded product to the lower limit value of the appropriate range, the average particle size of the kneaded product is judged as ◯, and as a result, the granulated product of the appropriate particle size is collected. The rate was also able to achieve 60 mass% or more.
On the other hand, as in Comparative Example 3, when the moisture value of the kneaded product was insufficient and the grain growth of the kneaded product could not be promoted, and the average particle size was x, the yield of the granulated product having an appropriate particle size was also deteriorated.

Moreover, the result of having examined the moisture value of the kneaded material when the stirring acceleration of the stirring blade is set to 70 m / s ² which is the upper limit value of the appropriate range will be described.
Here, Examples 3 and 5 are the results of setting the moisture value of the kneaded material to an appropriate range of 7% by mass or more and 12% by mass or less, and Comparative Example 4 exceeded the upper limit value of the appropriate range. This is the result of setting the value.

As is apparent from Table 3, with the increase of the moisture value of the kneaded product, a tendency to promote grain growth of the kneaded product was obtained. For this reason, as shown in Example 5, by setting the moisture value of the kneaded product to the upper limit value of the proper range, the average particle size of the kneaded product is judged as ◯, and as a result, the granulated product of the appropriate particle size is collected. The rate was also able to achieve 60 mass% or more.
On the other hand, as in Comparative Example 4, when the water content of the kneaded product was excessive and the kneaded product was coarsened, and the average particle size was x, the yield of the granulated product having an appropriate particle size was also deteriorated.
From the results of Tables 2 and 3 shown above, the moisture value of the kneaded product is set to 7% by mass or more and 12% by mass or less, and the average particle size of the kneaded product is set within an appropriate range, thereby granulating the appropriate particle size. It was confirmed that the yield of the product was increased.

Then, the result of having examined the stirring acceleration of the stirring blade at the time of setting the moisture value of a kneaded material to 7 mass% which is the lower limit of an appropriate range is demonstrated.
Here, Reference Example 1 and Comparative Example 5 are the results of setting the stirring acceleration of the stirring blades to be less than the lower limit value of the appropriate range.

As is apparent from Table 4, with the decrease in the stirring acceleration of the stirring blades, a tendency to promote grain growth of the kneaded product was obtained. In Reference Example 1 , although the stirring acceleration of the stirring blade was less than the lower limit value, the average particle size of the kneaded material was Δ because the moisture value of the kneaded material was within the appropriate range. For this reason, although the yield of the granulated material of an appropriate particle size did not reach Example 4, the favorable result was obtained.
On the other hand, as in Comparative Example 5, when the stirring acceleration was insufficient and the kneaded product was coarsened, and the average particle size was x, the yield of the granulated product having an appropriate particle size was also deteriorated.

Moreover, the result of having examined the stirring acceleration of the stirring blade when the moisture value of the kneaded product is set to 12% by mass which is the upper limit value of the appropriate range will be described.
Here, the reference example 2 and the comparative example 6 are the results of setting the stirring acceleration of the stirring blade to a value exceeding the upper limit value of the appropriate range.

As is apparent from Table 5, as the stirring acceleration of the stirring blades increased, the kneaded material was broken and its average particle size tended to be small. In Reference Example 2 , the stirring acceleration of the stirring blade exceeded the upper limit value, but the moisture value of the kneaded material was within an appropriate range, so the average particle size of the kneaded material was Δ. For this reason, although the yield of the granulated material of an appropriate particle size did not reach Example 5, the favorable result was obtained.
On the other hand, as in Comparative Example 6, when the stirring acceleration was excessively increased and the kneaded product was destroyed, and the average particle size was x, the yield of the granulated product having an appropriate particle size was also deteriorated.
From the results of Tables 4 and 5 shown above, even if the stirring acceleration is outside the proper range, depending on the degree, the moisture value of the kneaded product is set within the proper range, and the average particle size of the kneaded product is appropriate. It was confirmed that the yield of the granulated product having an appropriate particle size was increased by setting the content within the range.

As described above, the present invention has been described with reference to the embodiment. However, the present invention is not limited to the configuration described in the above embodiment, and the matters described in the scope of claims. Other embodiments and modifications conceivable within the scope are also included. For example, a case where the method for kneading a fine powder material of the present invention is configured by combining a part or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.
Further, in the above embodiment, the case where a binder is used when kneading the fine iron ore raw material has been described. However, if the kneaded material can obtain a sufficient strength, kneading without using the binder. A thing can also be manufactured.

It is explanatory drawing of the kneading | mixing method of the fine powder raw material which concerns on one embodiment of this invention. It is explanatory drawing which shows the relationship between the average particle size of a kneaded material, and the yield of the granulated material provided with the target particle size distribution. It is explanatory drawing of the mechanism in which the particle size of a kneaded material is determined. It is explanatory drawing which shows the relationship between the stirring acceleration of a stirring blade, the moisture content of a kneaded material, and the average particle diameter of a kneaded material. It is explanatory drawing which shows the relationship between the moisture content of a kneaded material, and the adhesive force of an iron ore raw material. It is explanatory drawing which shows the relationship between the stirring energy thrown into the iron ore raw material, and the adhesive force of an iron ore raw material. It is explanatory drawing which compared the relationship between the kneading | mixing time of a kneading machine, and the required water content of the kneaded material for obtaining the target average particle size.

Explanation of symbols

10: kneading machine, 11: drum mixer, 12: container, 13: stirring blade, 14: dryer

Claims (2)

In order to obtain a granulated product having a particle size distribution of 3 mm or more and 10 mm or less with a yield of 60% by mass or more, a cylindrical container containing an iron ore raw material containing 60% by mass or more of particles having a particle size of 250 μm or less, The iron ore raw material is kneaded by a kneader having a stirring blade for rotating and kneading the iron ore raw material to produce a kneaded product having an average particle size of 3 mm to 7 mm, and the kneaded product is put in a drum mixer A method of kneading the fine raw material for producing the granulated product ,
When the inner diameter of the container is D (m), the peripheral speed of the stirring blade is u (m / s), and the gravitational acceleration of the kneaded material is g (m / s ² ), the stirring acceleration ( u ² / D + g) is set within a range of 20 m / s ² or more and 70 m / s ² or less . In the kneading method of claim 1 Symbol placement of fine material, said iron Ishihara cost kneading time is 10 seconds or more, to the moisture content range of 7 wt% or more and 12 mass% or less of the kneaded material A method for kneading a fine powder raw material.

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