JP4795484B2 - Iron ore raw material grinding method - Google Patents

Description

  The present invention relates to a method for pulverizing iron ore raw materials, and in particular, to a pulverizing method for increasing the amount of fine powder of iron ore raw materials.

  In recent years, iron ore raw materials used in sintering machines have more fine powders than iron ore raw materials conventionally used. Therefore, when iron ore raw materials that have been used in recent years are put into a sintering machine without pretreatment, the air permeability of the sintering machine is hindered, and high-quality sintered ore is produced with high production efficiency. It is difficult. For this reason, after granulating the iron ore raw material with many said fine powders, the granulated material is thrown into the sintering machine.

  However, since the granulated product may collapse in the conveying process to the sintering machine or in the sintering machine if the strength is weak, by granulating an iron ore raw material having a particle size distribution suitable for granulation. It was necessary to increase the strength of the granulated product. However, in order to obtain a particle size distribution suitable for such granulation, among the fine powders of the iron ore raw material, fine powders for improving granulation property, for example, fine powders of several tens μm or less, especially several μm or less are used. It was not enough.

  Conventionally, in order to produce fine powder of iron ore raw material, a method of pulverizing iron ore raw material using a roll crusher has been adopted. For example, Patent Documents 1 and 2 disclose a technique of pulverizing an iron ore raw material with a roll pulverizer to generate fine powder having a particle size of 45 μm or less suitable for granulation. Patent Documents 3 and 4 disclose a technique for pulverizing an iron ore raw material supplied to a granulating apparatus with a roll pulverizer to generate fine powder having a particle size of 22 μm or less suitable for granulation. .

  As disclosed in the above Patent Documents 1 to 4, any of the conventional iron ore raw material pulverization methods, for example, an iron ore raw material that is easily pulverized, such as maramamba ore or high phosphorus block man ore, is a roll pulverizer. It was crushed by. However, for example, iron ore raw materials that are not easily pulverized, such as pellet feed, have a small particle size and high hardness, and are not easily pulverized, so there is little need for pulverization. It was mixed with the crushed iron ore raw material on the downstream side.

JP 2007-162127 A JP 2007-138244 A JP 2005-350770 A JP 2008-240159 A

  By the way, in order to improve the strength of the granulated material, it has been required to further increase the amount of fine powder of the iron ore raw material after pulverization. In order to further increase the amount of fine powder of this iron ore raw material, for example, it is conceivable to increase the facilities such as increasing the roll press force to make the crushing performance of the roll crusher excessively strong. However, in order to make the crushing performance of the roll crusher excessively strong, problems such as an increase in the cost of the roll crusher arise. Accordingly, there has been a demand for a method for increasing the amount of fine powder of iron ore raw material without increasing the equipment, such as increasing the roll pressing force by excessively enhancing the pulverization performance of the roll pulverizer.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to increase the amount of fine powder of iron ore raw material without increasing the equipment of the roll crusher. The object is to provide a new and improved method for grinding iron ore raw materials.

  When the inventors of the present application have conducted intensive research, the iron ore raw material, which is the object of grinding, is mixed with an iron ore raw material that is hard and hard to grind as a grinding aid, and the mixed iron ore raw material is mixed with a roll grinder. It has been found that the fine powder amount of the iron ore raw material obtained by grinding can be increased by grinding.

Accordingly, one aspect of the present invention is a method for pulverizing iron ore raw material using a roll pulverizer, and is at least one of maramamba ore, pisolite, high phosphorus blockman ore, serpentinite, and pyrbara blend that are to be pulverized . A second iron ore composed of at least one of riodose-pellet feed, MBR, MBR-PF, and lyodoce, which is higher in hardness than the first iron ore material. The raw materials are mixed as a grinding aid having a mixing ratio of 10 to 45% by mass , and the mixed first iron ore raw material and second iron ore raw material are charged into the roll grinder and pulverized. It is characterized by.

  Thereby, the 2nd iron ore raw material whose hardness is higher than the 1st iron ore raw material promotes the grinding | pulverization of the 1st iron ore raw material which is a grinding | pulverization object. Therefore, the amount of fine powder of the iron ore raw material obtained by pulverization is increased, and a particle size distribution suitable for granulation can be obtained.

  In addition, the grinding characteristics of the first and second iron ore raw materials are such that when the second iron ore raw material is pulverized alone using the roll grinder, the pulverization ratio is the first iron ore raw material. It is preferable that the pulverization rate is smaller than the pulverization rate when pulverizing alone. As a result, the second iron ore raw material itself is not easily pulverized by a roll pulverizer, and by promoting the pulverization of the first iron ore raw material to be pulverized, the amount of fine powder of iron ore is further increased. It is possible to obtain a particle size distribution suitable for. The above pulverization ratio is an index of how much the iron ore raw material after pulverization becomes smaller than that before pulverization, and “average particle diameter before pulverization” and “pulverization” with respect to “average particle diameter before pulverization”. It is defined as the ratio of the difference from the “average particle diameter after”.

  Moreover, it is preferable that the average particle diameter before pulverization of the second iron ore raw material is smaller than the average particle diameter before pulverization of the first iron ore raw material. Thereby, since a 2nd iron ore raw material enters in the clearance gap between 1st iron ore raw materials, the porosity of the mixed iron ore raw material falls. Accordingly, the second iron ore raw material further promotes the pulverization of the first iron ore raw material, so that the amount of fine iron ore powder can be further increased. In addition, the average particle diameter said here is the mass average particle diameter measured by the liquid layer sedimentation method (measurement method by an Andreasen pipette).

  Moreover, it is preferable that the mixing rate of the said 2nd iron ore raw material is 10-45 mass%. Thereby, the function as a grinding aid of the 2nd iron ore raw material can be improved. The mixing ratio is an index of how much of an iron ore raw material occupies a certain iron ore raw material, and is a ratio of the mass of all iron ore raw materials to the mass of a certain iron ore raw material. expressed.

  The second iron ore raw material is preferably a pellet feed. Moreover, it is preferable that the said pellet feed is a riodose-pellet feed.

It is a schematic diagram which shows the whole structure of the sintering equipment provided with the roll grinder used with the grinding method of the iron ore raw material which concerns on the 1st Embodiment of this invention. It is a graph which shows the relationship between the fine powder amount of an iron ore raw material, and the intensity | strength of a granulated material. It is a schematic diagram which shows the roll grinder used with the grinding method of the iron ore raw material which concerns on the same embodiment. It is a schematic diagram which shows the state which grind | pulverizes only the 1st iron ore raw material in the grinding method of the iron ore raw material which concerns on the same embodiment. It is a schematic diagram which shows the state which grind | pulverizes the mixture of the 1st iron ore raw material and the 2nd iron ore raw material in the grinding method of the iron ore raw material which concerns on the same embodiment. It is a graph which shows the particle size distribution before and behind the grinding | pulverization of West Angelus single used by the grinding method of the iron ore raw material which concerns on the Example of this invention. It is a graph which shows the particle size distribution before and behind the grinding | pulverization of Yandy alone used with the grinding method of the iron ore raw material which concerns on the same Example. It is a graph which shows the particle size distribution before and behind the grinding | pulverization of the serpentine used alone with the grinding method of the iron ore raw material which concerns on the Example. It is a graph which shows the particle size distribution before and behind the grinding | pulverization of the lyodoce-pellet feed used alone with the grinding method of the iron ore raw material which concerns on the same Example. It is a graph which shows the fine powder amount after grind | pulverizing with the grinding method of the iron ore raw material which concerns on the Example. It is a graph which shows the fine powder amount after grind | pulverizing with the grinding method of the iron ore raw material which concerns on the Example. As described above, according to the present invention, it is possible to increase the fine powder amount of the iron ore raw material without improving the pulverization performance of the roll pulverizer.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

[1. Overall configuration of sintering equipment]
FIG. 1 is a schematic diagram showing the overall configuration of a sintering facility equipped with a roll crusher according to this embodiment.

  As shown in FIG. 1, the sintering facility according to this embodiment mainly includes a pseudo granulation line 20, a pellet granulation line 30, and a sintering machine 40. The pellet granulation line 30 is a production line for producing a granulated product (hereinafter referred to as “sintered raw material pellet”) obtained by granulating an iron ore raw material mainly composed of fine powder. On the other hand, the pseudo granulation line 20 granulates an iron ore raw material containing fine powder and coarse particles, and a granulated product in which the fine powder is adhered to the coarse particles serving as core particles (hereinafter referred to as “pseudo granulated product”). It is a manufacturing line for manufacturing.

  First, the iron ore raw material will be described. The iron ore raw material is used as a sintering raw material for producing the sintered ore with the sintering machine 40. In the present embodiment, in the pellet granulation line 30, the iron ore raw material is composed of a first iron ore raw material that is easily pulverized and a second iron ore raw material that is not easily pulverized. The second iron ore material has a higher hardness than the first iron ore material. In addition, the second iron ore material has a smaller particle size than the first iron ore material. The first iron ore material can be any kind of iron ore material that can be easily crushed. Examples include iron ore raw materials with a large amount of crystal water such as Pilbara blend. In addition, the second iron ore raw material is not limited as long as it is an iron ore raw material that is not easily pulverized, and examples thereof include pellet feed such as riodose-pellet feed, MBR, MBR-PF, and riodose.

  Since the iron ore raw material containing a lot of these fine powders has poor granulation properties and the strength of the granulated material is low, the granulated material is not contained in the conveying process up to the sintering machine 40 or the sintering process in the sintering machine 40. Collapse phenomenon occurs. For this reason, when an iron ore raw material containing a large amount of such fine powder is directly introduced into the sintering machine 40, the air permeability is greatly deteriorated and the productivity of the sintered ore is hindered. Therefore, it is necessary to increase the strength of the granulated material by subjecting the iron ore raw material to a granulation treatment described later.

  The binder added to the kneader is, for example, a polyacrylic acid-based dispersant (for promoting solid crosslinking, such as an aqueous solution or a colloid added with a dispersant, from the viewpoint of enhancing granulation properties. At least one of quick lime and lignin.

  The iron ore raw materials as described above are classified according to the ore type and particle size, and granulated (pseudo-particle or pelletized) by two types of granulation lines, the pseudo-granulation line 20 and the pellet granulation line 30, respectively. Thus, sintered raw material pellets and pseudo-granulated products are produced. Each granulation line is described in detail below.

  First, the pseudo granulation line 20 will be described in detail. The pseudo-granulation line 20 is a line for manufacturing a pseudo-granulated product in which fine particles (for example, a particle size of 250 μm or less) are adhered to coarse particles (for example, a particle size of 3 mm or more) of an iron ore raw material serving as core particles. As shown in FIG. 1, the pseudo granulation line 20 includes a raw material tank 21 for storing an iron ore raw material containing coarse particles and fine powder, a sieve sorter 22, and a kneading for kneading the iron ore raw material with a water-soluble binder or the like. And a granulator 24 that granulates the kneaded iron ore raw material to produce a pseudo-granulated product.

  The raw material tank 21 stores, for example, iron ore raw materials (eg, pisolite ore) containing coarse particles and fine powder, and iron ore raw materials containing powdered coke, limestone, and the like. Is used to select coarse particles having a predetermined particle size or more (for example, 3 mm or more) and fine particles having a particle size smaller than that. Of these, the coarse particles can be used as core particles as they are, and are therefore conveyed to the granulator 24. On the other hand, the fine powder is put into a kneader 23 such as a Redige mixer and kneaded together with a binder to produce a kneaded product. As the kneading machine 23, a blade rotation type kneading machine such as a pro shear mixer or an Eirich mixer can be used.

  The kneaded product obtained by the kneader 23 and the coarse particles from the sieve sorter 22 are put into a granulator 24 such as a drum mixer. For example, a drum mixer, a pan pelletizer, or the like can be used as the granulator 24, and the kneaded material of the iron ore raw material is granulated (pseudo-particles) by the granulator 24 to become a pseudo-granulated product. Specifically, fine particles (for example, a particle size of 250 μm or less) contained in the powder coke, other iron ore, and binder are adhered around the core particles that are coarse particles by the granulation treatment by the granulator 24. A pseudo granulated product (for example, a particle size of 1 to 10 mm) is produced.

  Next, the pellet granulation line 30 will be described in detail. The pellet granulation line 30 is a line for producing sintered raw material pellets, which are granulated products obtained by granulating an iron ore raw material mainly composed of fine powder having a predetermined particle size or less. The sintered raw material pellet is, for example, a granulated product having a particle size of 1 to 10 mm and an average particle size of 5 mm.

  As shown in FIG. 1, the pellet granulation line 30 includes a raw material tank 31 for storing a first iron ore raw material mainly composed of fine powder, a sieve sorter 32, and a raw material for storing a second iron ore raw material.糟 33, a pulverizer 50 for pulverizing the first iron ore raw material and the second iron ore raw material, a kneader 34 for kneading the crushed iron ore raw material and a binder, and the kneaded iron ore raw material Are granulated to produce sintered raw material pellets, a sieve sorter 36, and a dryer 37 for drying the granulated sintered raw material pellets.

  The raw material tank 31 of the pellet granulation line 30 stores a first iron ore raw material containing a large amount of fine powder, such as maramamba ore (brand: West Angelus), high phosphorus block man ore, and the like. As the first iron ore raw material, coarse particles having a predetermined particle size or more are sorted and removed in advance by a sieve sorter (not shown) or the like to obtain a fine powder (for example, a particle size of 3 mm or less) to some extent. From the viewpoint of facilitating granulation and expressing the strength of the granulated product.

  The first iron ore raw material supplied from the raw material tank 31 is first sieved by the sieve sorter 32, and fine powder having a predetermined particle size (for example, 3 mm) or less is supplied to the pulverizer 50. On the other hand, the particles having a predetermined particle diameter or more are supplied to the granulator 24 of the pseudo-granulation line 20 to be used as the core particles of the above-described pseudo-granulated product.

  On the other hand, all of the second iron ore raw material supplied from the raw material basket 33 has been directly input to the kneader 34 in the past. However, for the second iron ore raw material of the present embodiment, fine powder such as riodose-PF (average particle size 0.055 mm or less) is supplied to the pulverizer 50. The pulverizer 50 is composed of, for example, a roll pulverizer. The pulverizer 50 pulverizes the supplied first iron ore raw material and second iron ore raw material to a predetermined particle size distribution. Thus, the latter stage granulation process can be made easier by grind | pulverizing and pulverizing and sizing the 1st iron ore raw material and the 2nd iron ore raw material. The pulverizer 50 is a feature of the present embodiment, and details will be described later.

  Next, in the kneader 34, the binder and water are added to adjust the water content, and then the fine iron ore raw material is kneaded. In the present embodiment, as the kneading machine 34, for example, a blade rotation type kneading machine such as a Redige mixer or a Proshear mixer is used. Thus, in this embodiment, it is set as the structure which improved the kneading | mixing capability of an iron ore raw material and a binder by installing the kneading machine 34 in the front | former stage of the granulator 35. FIG.

  The sintered raw material after being kneaded by the kneader 34 is put into a granulator 35 and granulated. As the granulator 35, for example, a drum mixer or a pan pelletizer can be used. By the granulation by the granulator 35, for example, sintered raw material pellets which are substantially spherical granules having a particle diameter of 1 to 10 mm, preferably 3 to 6 mm (for example, an average particle diameter of 5 mm) are manufactured. . As for the particle size distribution of the sintered raw material pellets, for example, a particle size of 3 mm or more may be 70% by mass.

  The sintered raw material pellets thus produced are dried by a dryer 37 after a granulated material having a predetermined particle size or more is sorted by a sieve sorter 36.

  As described above, the pseudo-granulated product granulated in the pseudo-granulation line 20 and the sintered raw material pellets granulated in the pellet granulation line 30 are blended at a predetermined blending ratio, and the sintering machine 40. The sintering machine 40 sinters the two kinds of sintered raw material granules to produce a sintered ore. The sintered ore is supplied to the blast furnace after being crushed by a crusher (not shown) and cooled by a sintered cooler (not shown).

  The overall configuration of the sintering facility according to the present embodiment has been described above. In the present embodiment, in the pellet granulation line 30, the mixture of the first iron ore raw material and the second iron ore raw material is pulverized by the pulverizer 50 in order to increase the amount of fine powder. The obtained fine powder is put into the kneader 34 and kneaded. The present embodiment is characterized by a method of pulverizing the iron ore raw material by the pulverizer 50. A feature is that the second iron ore raw material, such as pellet feed, which has been put directly into the kneader 34 in the past is mixed with the first iron ore raw material, and then the iron ore raw material is pulverized by the pulverizer 50. Have. A method for pulverizing the iron ore raw material of the roll pulverizer 50, which is a feature according to this embodiment, will be described later (see FIGS. 3 to 5).

[2. Relationship between the amount of fine iron ore powder and granulated material]
Next, with reference to FIG. 2, it demonstrates in detail that the granulated material of high intensity | strength can be obtained by increasing the fine powder amount of an iron ore raw material. FIG. 2 is a graph showing the relationship between the amount of fine powder of the iron ore raw material and the strength of the granulated product. Here, the fine powder in FIG. 2 means iron ore particles having a particle size of less than 10 μm. The particle size shown in FIG. 2 is based on the liquid phase sedimentation method (measurement method using Andreazen pipette), and is measured based on the sedimentation rate in the liquid layer, which varies depending on the particle size.

  As shown in FIG. 2, for any of the three types of iron ores (iron ore A, iron ore B, and iron ore C) mentioned in the example, the strength of the granulated material is improved as the amount of fine powder increases. I understand. That is, in order to improve the strength of the granulated product, it is necessary to increase the fine powder amount of the iron ore raw material. Therefore, in the pulverization method of this embodiment, the first iron ore raw material is not pulverized alone, but the first iron ore raw material is mixed with the second iron ore raw material and pulverized. As a result, the second iron ore raw material becomes a grinding aid, which facilitates the grinding of the first iron ore raw material.

[3. Configuration of roll crusher]
Next, with reference to FIG. 3, the roll grinder 50 used with the grinding method of the iron ore raw material which concerns on 1st Embodiment is demonstrated. FIG. 3 is a schematic view showing a roll crusher 50 used in the iron ore raw material crushing method according to the present embodiment.

  As shown in FIG. 3, the roll crusher 50 is a biaxial roll type compression crusher. The roll crusher 50 mainly includes a driven roll 51, a fixed roll 53, and a hopper 55.

  As the driven roll 51 and the fixed roll 53, those having a smooth surface as shown in the figure can be used, but those having irregularities on the surface may be used. Moreover, the driven roll 51 and the fixed roll 53 may be formed in the same magnitude | size, and may be formed so that one may become larger than the other. Furthermore, it is desirable that the respective center axes (not shown) of the driven roll 51 and the fixed roll 53 are parallel and also parallel to the surface of the installation place such as the ground. That is, it is desirable that the driven roll 51 and the fixed roll 53 are installed horizontally.

  Further, the driven side roll 51 and the fixed side roll 53 have a rotation shaft portion 52 and a rotation shaft portion 54, respectively. The rotation shaft portion 52 and the rotation shaft portion 54 are formed so as to pass through the central axes of the driven side roll 51 and the fixed side roll 53, respectively.

  The hopper 55 is disposed on the driven roll 51 and the fixed roll 53 with a slight gap from the roll surface where the lower part rotates. The hopper 55 can have any size and shape as long as the iron ore raw material can be input. The upper part of the hopper 55 has a substantially rectangular parallelepiped shape, for example, as shown in FIG.

  The driven roll 51 is rotated by the rotating shaft portion 52. Further, the fixed-side roll 53 is also rotated by the rotation shaft portion 54. What rotates the rotating shaft part 52 and the rotating shaft part 54 is a drive device (not shown) which consists of a motor, a reduction gear, etc., for example. Either one driving device is provided for each roll, or both the driven side and fixed side rolls are driven from one motor via a reduction gear and two output shafts. The driven roll 51 is subjected to a roll reduction force (force F in the direction of the arrow in FIG. 3) by a hydraulic cylinder (not shown). The hopper 55 has a side wall so that the iron ore raw material to be input does not overflow from between the rolls.

  In the roll crusher 50 having such a structure, first, an iron ore raw material is charged into the hopper 55. In order from the iron ore raw material accumulated below the hopper 55, the material is pulverized when passing between the driven roll 51 and the fixed roll 53. The pulverization is realized by applying a roll rolling force F to the driven roll 51 in a state where the driven roll 51 and the fixed roll 53 are rotated by the rotary shaft 52 and the rotary shaft 54, respectively. As will be described in detail below, in the present embodiment, after the first iron ore raw material and the second iron ore raw material are mixed, the mixed first iron ore raw material and second iron ore raw material are mixed. Are put into the hopper 55. Since the first iron ore raw material is easily pulverized and the second iron ore raw material is high in hardness and difficult to pulverize, the first iron ore raw material is pulverized mainly by the roll reduction force, and the second iron ore raw material Mainly serves as a grinding aid for promoting the grinding of the first iron ore raw material.

[4. Crushed state of iron ore raw material]
Next, with reference to FIG. 4 and FIG. 5, the iron ore raw material pulverization method by the roll pulverizer 50 having such a configuration will be described in more detail. FIG. 4 is a schematic diagram showing a conventional method for grinding iron ore raw materials. The iron ore raw material pulverization method according to the present embodiment is realized by the roll pulverizer 50. Hereinafter, a description will be given with reference to FIGS. 4 and 5.

  As shown in FIG. 4, the first iron ore raw material is charged into the hopper 55 of the roll crusher 50. As a result, the first iron ore raw material tends to pass between the driven roll 51 and the fixed roll 53. At that time, the first iron ore raw material is crushed so as to pass between the rolls while being compressed by the driven roll 51.

  Conventionally, only the first iron ore raw material that is easily pulverized has been used as the iron ore raw material pulverized by the roll pulverizer 50. For example, maramamba ore (brand: West Angelus), pisolite (brand: Yandi), serpentine, and the like have been mixed. In addition, iron ore raw materials with a large amount of crystal water such as high phosphorus Brockman ore and Pirbara blend are also used. The above-mentioned Mara Mamba ore is an Australian iron ore mainly composed of a goethite-martite structure. The high phosphorus Brockman ore is an Australian iron ore mainly composed of hematite and goethite. On the other hand, refractory iron ore raw materials with low crystallization water, such as riodose, MBR, pellet feed, etc., which have a dense structure, are mixed with the crushed iron ore raw materials at the stage of kneading in a kneader without pulverization. It has been. Here, the pellet feed is obtained by collecting iron-rich particles by gravitational sedimentation after pulverizing the ore. For example, riodose-pellet feed (same as riodose-PF in the figure and table), MBR-PF. Etc. The above MBR-PF is a Brazilian iron ore raw material mainly composed of a hematite structure, is relatively high in hardness, and has an average particle size of less than 0.125 mm.

  In order to improve the strength of the granulated product, the amount of fine powder of the iron ore raw material after pulverization has been required to be further increased with respect to the pulverization method using the conventional roll pulverizer 50 as described above. Until now, in order to further increase the amount of fine powder of this iron ore raw material, the pulverization performance of the roll pulverizer 50 could only be improved. More specifically, the pulverization of the iron ore raw material proceeds as the roll rolling force by the driven roll 51 increases. To increase the roll rolling force, a hydraulic cylinder (not shown) or a driven roll is used. It was necessary to improve the performance of 51 or the fixed roll 53 and the structure (not shown) that supports them. That is, it has been necessary to improve the performance of the roll crusher 50 with great cost.

  Next, the iron ore raw material grinding method according to the present embodiment will be described with reference to FIG. FIG. 5 is a schematic diagram showing a method for grinding an iron ore raw material according to the present embodiment.

  As shown in FIG. 5, the iron ore raw material is charged into the hopper 55 of the roll crusher 50. Unlike the example shown in FIG. 4, in the example shown in FIG. 5, the first iron ore raw material West Angelus, Yandi, and serpentine are mixed with the second iron ore raw material Riodose-pellet feed. Then, the mixed iron ore raw material is charged into the hopper 55 of the roll crusher 50. That is, the second iron ore raw material that is not easily pulverized is mixed with the first iron ore raw material that is easily pulverized, and then pulverized by the roll pulverizer 50.

  Here, the hardness of the iron ore raw material is shown in Table 1.

  With reference to Table 1, the hardness of the iron ore raw material will be described by taking West Angelus, Yandi, and Riodose as examples. The ease of pulverization is represented by the strength of mechanical properties. For example, the higher the hardness, the less pulverization, and the lower the hardness, the easier the pulverization. In addition, hardness is the hardness prescribed | regulated in JIS, for example, and is measured by a hardness test.

Easiness of pulverization is also expressed by mechanical properties other than hardness, and is evaluated by average crushing strength as shown in Table 1. Here, the average crushing strength is one parameter of mechanical characteristics, and the average crushing strength shown in Table 1 is measured by the following measurement procedures (1) to (3).
(1) After drying the iron ore material to be subjected to the test, the particle size is adjusted to 2 to 2.8 mm with a sieve.
(2) The crushing strength of each iron ore raw material is measured by a compression tester (PT-200N manufactured by Minebea, maximum compressive strength: 200 N, head descending speed 5 mm / min).
(3) For each iron ore raw material, measure 90 ingot strengths and determine the average value (N / piece).

  The average crushing strength measured by this measurement procedure is 61 N / piece for West Angelus, 54 N / piece for Yandy, and 80 N / piece for Rio Doce. That is, riodose having a high average crushing strength is difficult to be crushed. On the other hand, West Angelus and Yandy are relatively easily crushed.

  The ease of grinding is also evaluated by the grinding ratio. The pulverization ratio is defined by a reduction rate of the average particle diameter after pulverization with respect to the average particle diameter before pulverization, and is obtained by the following formula 1.

  The average particle size before pulverization refers to the average particle size before pulverization of each iron ore raw material alone, and the average particle size after pulverization refers to the average particle size after pulverization of each iron ore raw material alone.

  Again, a description will be given with reference to FIG. Thus, since the 2nd iron ore raw material which is hard to grind | pulverize with high hardness, such as riodose, is mixed with the 1st iron ore raw material easy to grind | pulverize and grind | pulverizes with the roll grinder 50, 2nd iron ore The raw material facilitates the pulverization of the first iron ore raw material as a pulverization aid. Therefore, the amount of fine powder of the iron ore raw material can be increased.

  Moreover, in order for this 2nd iron ore raw material to exhibit the function as a grinding aid more, it is desirable to raise the filling rate between the 1st iron ore raw materials of the roll grinder 50 more. That is, it is desirable that the second iron ore material has a smaller average particle size than the first iron ore material. The smaller the average particle size, the higher the filling ratio between the first iron ore raw materials of the roll crusher 50, and when the iron ore raw material passes between the rolls, the first iron ore raw material is compared with the first iron ore raw material. It is considered that the roll reduction force is more likely to act, and the pulverization of the first iron ore raw material is promoted. Thus, not only from the viewpoint of the mechanical characteristics described above, but also from the viewpoint of physical characteristics such as the average particle diameter, a pellet feed such as a riodose-pellet feed having a relatively small particle diameter is used as a grinding aid. It is desirable to be used.

  As described above, in the present embodiment, the first iron ore material that is easily pulverized is mixed with the second iron ore material that is hard and difficult to be pulverized as a pulverization aid, and the mixed iron ore material is mixed with a roll pulverizer. Smash. Therefore, the second iron ore raw material having high hardness and not easily pulverized facilitates pulverization of the first iron ore raw material that is easily pulverized. In this way, it is possible to increase the fine powder amount of the iron ore raw material without improving the performance of the roll crusher. As a result, it is possible to improve the productivity of the sintered ore by improving the strength of the granulated material and increasing the air permeability in the sintering process.

  In addition, the brand of the iron ore raw material which has been described above has a fact that it is given based on the name of the mine from which the iron ore raw material is collected. Therefore, for example, even if the name of the iron ore raw material currently named “Riodose-pellet feed” is changed due to a change in the name of the mine, the substantially same iron ore raw material is the same as the riodose-pellet feed in this embodiment. Considered the same iron ore raw material.

  Examples of the present invention will be described below. In addition, the numerical value etc. which are used in the following examples are illustrations for facilitating the understanding of the present invention, and the present invention is not limited to the following examples.

[Crushing test of each iron ore raw material alone]
First, the crushing test before and after crushing each iron ore raw material alone will be described.

  In this test, the particle size distribution before and after pulverization by a roll pulverizer using each iron ore raw material alone was measured. By measuring the particle size distribution of each iron ore material before and after being pulverized by a roll pulverizer, the ease of pulverization of each iron ore material when the iron ore materials are mixed and pulverized by a roll pulverizer is specified. be able to.

  The iron ore raw materials used in this test were West Angelus, Yandi, and Rio Doce-pellet feed (hereinafter, the same as Rio Doce-PF shown in the figures and tables) and serpentine shown in Table 1 above. It is a rock. The West Angelus, Yandi, and Rio Doce-pellet feeds are as described above. Serpentine is an auxiliary material for adjusting the MgO component in the sintered ore.

  This test was performed by measuring the particle size distribution before each iron ore raw material was pulverized with a roll pulverizer and after pulverization alone.

The test conditions for this test are as follows. The following particle size distribution measurement by the laser diffraction / scattering method is performed based on the amount of scattered light and the scattering direction of light scattered when the particles are irradiated with laser light.
・ Roll pulverizer ・ Two-axis roll reduction pulverizer ・ Roll size 250mm diameter × 100mm length ・ Roll reduction force 6 tons ・ Roll rotation speed 42rpm
・ Particle size distribution measurement Laser diffraction / scattering method

  Next, the test results of this test will be described with reference to FIGS. FIG. 6 is a graph showing the particle size distribution before and after grinding of West Angelus alone. FIG. 7 is a graph showing the particle size distribution before and after the grinding of Yandi alone. FIG. 8 is a graph showing the particle size distribution before and after crushing serpentine alone. FIG. 9 is a graph showing the particle size distribution before and after pulverization of the riodose-pellet feed alone.

In addition, the definition of each term in FIGS. 6-9 is as follows.
-Cumulative mass ratio: The mass ratio (mass%) of the iron ore raw material that is equal to or smaller than the particle diameter to the total iron ore raw material at a certain particle diameter
-Mass ratio before pulverization: Mass ratio (mass%) of iron ore raw material having each particle size with respect to the iron ore raw material before being pulverized by a roll pulverizer
・ Mass ratio after pulverization: Mass ratio (mass%) of iron ore raw material having each particle size with respect to iron ore raw material after being pulverized by a roll pulverizer

  As shown in FIG. 6, when West Angelus alone is pulverized by a roll pulverizer, the cumulative mass ratio after pulverization is increased in all particle sizes with respect to the cumulative mass ratio before pulverization. Further, as shown in FIG. 7, even when Yandi alone is pulverized by a roll pulverizer, the cumulative mass ratio after pulverization is increased in all particle diameters with respect to the cumulative mass ratio before pulverization. Furthermore, as shown in FIG. 8, even when serpentinite alone is pulverized by a roll pulverizer, the cumulative mass ratio after pulverization is increased in all particle sizes with respect to the cumulative mass ratio before pulverization. However, as shown in FIG. 9, when the riodose-pellet feed alone was pulverized with a roll pulverizer, although the cumulative mass ratio after pulverization slightly increased with respect to the cumulative mass ratio before pulverization, West Angelus , Yandi, and Serpentinite have not increased.

  Here, Table 2 shows the pulverization ratios quantitatively representing the ease of pulverization of the riodose-pellet feed, West Angelus, Yandi, and serpentine by a roll pulverizer.

  In addition, the average particle diameter in Table 2 is a particle diameter (mm) at which the cumulative mass ratio is 50%. Further, the pulverization ratio is a ratio represented by Formula 1 above.

  As shown in Table 2, the grinding ratio of each iron ore raw material is 67% for West Angelus, 92% for Yandi, 59% for serpentinite, and 18% for lyodose-pellet feed. The iron ore raw material having a high pulverization ratio is easily pulverized by a roll pulverizer. That is, West Angelus, Yandi, and serpentine, which are the first iron ore raw materials, are relatively easily pulverized by the roll pulverizer, while the riodose-pellet feed, which is the second iron ore raw material, is crushed by the roll pulverizer. It means that it is hard to be crushed. Thus, as shown in Table 1, the riodoce-pellet feed, which is the second iron ore raw material, is less pulverized than the first iron ore raw material. One of the factors is considered to be higher hardness than stone raw materials. In addition, as shown in Table 2, the riodoce-pellet feed is less likely to be pulverized than the first iron ore raw material. A small factor is considered to be a factor.

[Crushing test of mixed iron ore raw materials]
Next, a grinding test of the mixed iron ore raw material according to the present embodiment will be described.

  In this test, the first iron ore raw material, West Angelus, Yandi, serpentinite, and the second iron ore raw material, riodose-pellet feed, were mixed and then pulverized by a roll pulverizer. The particle size distribution before and after grinding was measured (Examples 1 and 2). Moreover, after each iron ore raw material was pulverized by a roll crusher, the particle size distribution when each iron ore raw material was mixed was calculated based on the measurement result of the particle size distribution obtained by pulverizing each iron ore raw material alone (Comparative Example). ). By this test, it is demonstrated that the iron ore raw material such as riodose-pellet feed is mixed with high hardness and hard to be crushed and then pulverized with a roll pulverizer to increase the amount of fine powder of iron ore raw material. it can.

  As shown in Table 3, in Example 1, the mixing ratio of the first iron ore raw material is 49 mass%, 22 mass%, and 6 mass% in the order of West Angelus, Yandi, and serpentine. Moreover, the mixing rate of the riodose-pellet feed which is a 2nd iron ore raw material is 23 mass%. On the other hand, in Example 2, the mixing ratio of the first iron ore raw material is 49% by mass, 0% by mass, and 6% by mass in the order of West Angelus, Yandi, and serpentine. Moreover, the mixing rate of the riodose-pellet feed which is a 2nd iron ore raw material is 45 mass%. Except that each iron ore raw material was mixed at such a mixing ratio and then pulverized by a roll pulverizer, the test conditions were exactly the same as those used in the above pulverization test of each iron ore raw material alone. In addition, a mixing rate is represented by the following numerical formula 2, and like this example, all the iron ore materials mixed are not limited to the first iron ore material and the second iron ore material. .

  First, with reference to FIG. 10, the measurement result of Example 1 and a comparative example is demonstrated. FIG. 10 is a graph showing the relationship between the mixing ratio of the riodose-pellet feed and the mass ratio of the amount of fine powder after pulverization. The graph shown in FIG. 10 is calculated based on the above-described particle size distribution measurement. Here, in this example, a powder having a particle size of less than 8 μm is used as a fine powder. Further, “pulverization after pre-mixing” shown in FIG. 10 means an iron ore raw material obtained by mixing the first iron ore raw material and the second iron ore raw material and then pulverizing, and is plotted in a graph. Represents the result of the mass ratio of the fine powder of the iron ore raw material (iron ore raw material having a particle size of less than 8 μm). “Mixed after pulverization” means an iron ore raw material obtained by pulverizing the first iron ore raw material and the second iron ore raw material alone, and the plot of the graph shows the iron ore The result of the mass ratio of the fine powder (the iron ore raw material whose particle size is less than 8 micrometers) of a stone raw material is represented. Furthermore, “before pulverization” means an iron ore raw material obtained by mixing the first iron ore raw material and the second iron ore raw material before pulverization, and the plot of the graph is a fine powder of the iron ore raw material. The result of the mass ratio of (the iron ore raw material whose particle size is less than 8 micrometers) is represented.

  Further, in the graph shown in FIG. 10, the mixing ratio of the riodose-pellet feed is constant at 49: 22: 6 at the mixing ratio of West Angelus, Yandi, and serpentine at any mixing ratio. is there. That is, for example, when the mixing ratio of the riodose-pellet feed is 10% by mass, the mixing ratio of West Angelus, Yandi, and serpentine is 49: 22: 6, Is 10% by mass mixed with respect to all iron ore raw materials. Similarly, for example, 20% by mass means that the mixing ratio of West Angelus, Yandi, and serpentine is 49: 22: 6, and the riodose-pellet feed is 20 with respect to all iron ore raw materials. Refers to mixing by mass%.

  As shown in FIG. 10, when the mixing ratio of the riodose-pellet feed is 23% by mass, the amount of fine powder after pulverization is about 4.5% by mass in “pulverization after pre-mixing” compared to “mixing after pulverization”. Improved. Even when the mixing ratio of West Angelus, Yandi, and serpentine is 49: 22: 6 and the mixing ratio of the riodose-pellet feed is 10% by mass, In “pulverization after premixing”, the amount of fine powder after pulverization was improved by about 1% by mass. Similarly, even when the mixing ratio of the riodose-pellet feed was 15% by mass, the amount of fine powder after pulverization was improved by about 2.5% by mass in “grinding after pre-mixing” compared to “mixing after pulverization”. .

  Next, with reference to FIG. 11, the measurement result of Example 2 and a comparative example is demonstrated. FIG. 11 is a graph showing the relationship between the mixing ratio of the riodose-pellet feed and the mass ratio of the fine powder amount after pulverization, as in FIG. The graph shown in FIG. 11 was prepared in the same manner as the graph shown in FIG. 10 except that the mixing ratio shown in Table 3 was related to Example 2.

  Further, the mixing ratio of the riodose-pellet feed in the graph shown in FIG. 11 is 49: 6 at the mixing ratio of West Angelus and serpentine regardless of the mixing ratio of the graph shown in FIG. It is constant. That is, for example, when the mixing ratio of riodose-pellet feed is 10% by mass, the mixing ratio of West Angelus and serpentine is 49: 6, and riodose-pellet feed is all iron ore. It means that 10 mass% is mixed with respect to the raw material. Similarly, for example, 20% by mass means that the mixing ratio of West Angelus and serpentinite is 49: 6, and the riodose-pellet feed is mixed by 20% by mass with respect to all iron ore raw materials. Refers to that.

  As shown in FIG. 11, when the mixing ratio of the riodose-pellet feed is 45% by mass, the amount of fine powder after pulverization is about 8.5% by mass in the “pulverization after premixing” with respect to “mixing after pulverization”. Improved.

  As described above, in both cases of Example 1 and Example 2, it was found that the amount of fine powder after pulverization was greatly improved in “pulverization after premixing” as compared with “mixing after pulverization”. This result shows that the second iron ore raw material, riodose-pellet feed, has high hardness and acts as a grinding aid, so that the first iron ore raw material, West Angelus, Yandi, and serpentine can be crushed. This is considered to be caused by promoting with a roll crusher. In addition, this result shows that the second iron ore raw material, riodose-pellet feed, has a smaller particle size than the first iron ore raw material, West Angelus, Jandi, and serpentine, This is also attributed to the improvement of the rate. That is, when the riodose-pellet feed is not between the rolls of the roll crusher, the filling rate between the first iron ore raw materials is low, and the first iron ore raw material easily passes between the rolls. However, when the riodose-pellet feed is between the rolls of the roll crusher, the filling rate between the first iron ore materials is increased, and the iron ore materials are less likely to pass between the rolls. Therefore, it is considered that the pressure of the roll pulverizer easily acts on the iron ore raw material, and the iron ore raw material is easily pulverized. As a result, the amount of fine powder of iron ore raw material is considered to increase.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the above embodiment, the roll crusher used in the iron ore raw material crushing method of the present invention is a biaxial roll type compression crusher, but the present invention is not limited to such an example. For example, a backup roll may be provided. Moreover, it is not limited to the example shown in FIG. 3, If it can grind | pulverize an iron ore raw material, it can change a design into arbitrary structures.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to increase the fine powder amount of an iron ore raw material, without improving the grinding | pulverization performance of a roll grinder, and industrial applicability is high.

20 Pseudo-granulation line 21 Raw material tank 22 Sieve sorter 23 Kneading machine 24 Granulator 30 Pellet granulation line 31 Raw material tank 32 Sieve sorter 33 Raw material tank 34 Kneading machine 35 Granulator 36 Sieve sorter 37 Dryer 40 Baking Kneading machine 50 Crusher 51 Drive side roll 52 Rotating shaft part 53 Fixed side roll 54 Rotating shaft part 55 Hopper

Claims (4)

A method for grinding iron ore raw material using a roll grinder,
Marra Mamba ore is crushed object, Pisoraito, Korin Brockmann ores, serpentinite, the first iron ore raw material consisting of at least one of Pilbara blend is the first higher hardness than iron ore raw material CVRD The first iron ore raw material comprising at least one of pellet feed, MBR, MBR-PF, and riodose is mixed as a grinding aid having a mixing ratio of 10 to 45% by mass, and the first mixed The iron ore raw material and the second iron ore raw material are charged into the roll grinder and pulverized.   The pulverization characteristics of the first and second iron ore raw materials are obtained by using the roll pulverizer as an index with the pulverization ratio defined by the reduction rate of the average particle diameter after pulverization with respect to the average particle diameter before pulverization. The pulverization ratio when pulverizing the iron ore raw material of 2 alone is smaller than the pulverization ratio when pulverizing the first iron ore raw material alone using the roll pulverizer. The method for pulverizing the iron ore material according to claim 1.   3. The iron ore material according to claim 1, wherein an average particle size of the second iron ore material before pulverization is smaller than an average particle size of the first iron ore material before pulverization. Grinding method. The said 2nd iron ore raw material is a riodose- pellet feed, The grinding method of the iron ore raw material of any one of Claims 1-3 characterized by the above-mentioned.

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