JP5835099B2 - Pretreatment method of sintering raw material - Google Patents

Description

    The present invention relates to a pretreatment method for a sintered material when granulating the sintered material.

Sintering raw material is powdered ore made of iron ore, blending auxiliary materials and coagulants to adjust the ingredients as necessary, and mixing and granulating this powdered ore with water and binder before firing, The amount of fine powder charged into the sintering machine is reduced. This granulation is an important operation for maintaining and improving sintering productivity, and various granulation techniques have been proposed.
For example, in Patent Document 1, in the production of sintered ore, two series of granulation lines are used, and the mixing ratio of quick lime used in each granulation line without changing the total amount of quick lime used in both lines. A method of improving the granulation property of the sintering raw material by changing the above is disclosed. This makes it possible to use a raw material with poor sinterability (maramanba ore), which is fine powder and high crystal water, as a sintering raw material.

JP-A-5-9601

  However, in recent years, the number of difficult-to-granulate powdered ores obtained by crushing inferior iron ore and flotation processing (that is, raw materials for fine powder) has increased. Then, it was necessary to significantly increase the amount of expensive binder added.

  The present invention has been made in view of such circumstances, suppressing an increase in the amount of binder used, improving the granulation property of the sintered raw material, enabling granulation of a fine powder material having difficult granulation property, An object of the present invention is to provide a pretreatment method of a sintering raw material that can be used for the production of sintered ore by suppressing the collapse of the granulated product.

  The sintering raw material pre-treatment method according to the present invention that meets the above-mentioned object is a sintering raw material that uses a fine powder raw material that is a fine ore having a particle size of 500 μm under and 50 μm under 10 μm under 5% by weight as iron ore. The A group is granulated by using either 1 or 2 of quicklime and slaked lime having a particle size of 250% by mass of 250 μm or less to obtain a granulated product.

  In the pretreatment method of the sintered raw material according to the present invention, as the iron ore, a sintered raw material B group using a powdered ore having a particle size of less than 50% by mass or less than 5% by mass of 10 μm is 10 μm under 250 μm. One or two of quicklime and slaked lime having a particle size of 50% by mass or more and less than 50% by mass are blended, and granulated before or after merging with the granulated product of the sintered raw material A group to obtain a granulated product. You can also.

In the sintering raw material pretreatment method according to the present invention, it is preferable that at least a coagulating material that generates heat by oxidation is added to the sintering raw material group B.

The sintering raw material pretreatment method according to the present invention uses a sintered raw material A group using a fine powder raw material as iron ore, either 1 or 2 of quick lime and slaked lime having a particle size of 250 μm under 50% by mass or more. Therefore, without significantly increasing the amount of quicklime or slaked lime used as a binder, the granulating property can be improved and the sintered raw material group A can be granulated. Sintered ore can be manufactured with suppression.
This is because when only the sintered raw material A group having a particle size composition of about 10 μm over 500 μm is granulated, a space is formed inside the granulated material, so quick lime and slaked lime having the above particle sizes are used. By using these, the space inside the granulated product is filled.
The Mara Mamba ore described in Patent Document 1 is a sintering raw material (sintering raw material corresponding to a sintering raw material B group to be described later) with a large amount of fine particles of 10 μm under, which is about the above-described sintering raw material group A. Does not exhibit difficult granulation.

Further, when granulating by mixing either 1 or 2 of quick lime and slaked lime having a particle size of 250 mass% under 10% by mass and less than 50% by mass in the sintering raw material group B, all of the quick lime and slaked lime are finely granulated. The granulating property of the sintering raw material group A can be ensured without conversion.
This is because the sintered raw material B group has a particle size that makes it easy to granulate as compared with the above-described sintered raw material A group, so that relatively fine-grained quicklime and slaked lime are used for the sintered raw material A group. Moreover, it is because comparatively coarse-grain quicklime and slaked lime can be used for the sintering raw material B group.

When at least a coagulant is added to the sintering raw material group B, the sintering phenomenon (oxidation exothermic phenomenon) can be promoted, so that the amount of the coagulant added can be suppressed. Further, when the amount of the coagulant is not changed, the productivity of the sintered ore can be improved.
In general, the coagulant is added to the sintering raw material for the purpose of securing the strength of the sintered ore. However, the use of the coagulant causes an increase in cost, so the addition amount is required to be the minimum necessary. Yes. On the other hand, if the agglomerated material is buried inside the granulated material due to adhesion of fine powder (particle size composition: about 10 μm over 500 μm under), it becomes difficult to contribute to the oxidation exothermic phenomenon, so it becomes difficult to suppress the amount of the agglomerated material added. .
For this reason, burying of the coagulant can be suppressed by adding the coagulant to the sintered raw material group B with a small amount of fine powder.

It is a graph which shows the influence which the kind of binder to add has on the granulation property of a granulated material. (A) is a graph showing the effect of the proportion of 500 μm under in the raw material on the powder rate after granulation, (B) is a graph showing the effect of the proportion of the 10 μm under in the raw material on the powder rate after granulation is there. It is a graph which shows the influence which the ratio of 250 micrometers under in quicklime has on the powder rate after granulation. (A)-(E) are explanatory drawings which respectively show the granulation process of a sintering raw material. It is a graph which shows the influence which the addition ratio of the coagulant | flocculant to an easily granulated raw material has on sintering productivity.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
First, the background to the present invention will be described.
First, the granulation property of the fine powder raw material which shows difficult granulation property among powder ores (iron ore) is demonstrated.
The finer raw material (iron ore) with very small particles (fine particles) with a mesh size of 10 μm or less, less than 5% by mass, and very much with particles of 500 μm or less with 50% by mass or more, is different from ordinary iron ore. It has been found that this feature can be obtained by repeating, for example, iron ore crushing treatment and water specific gravity separation treatment. In the measurement of the mass% of particles having a size of 500 μm or less, a fine powder material (2 kg) was dried at 150 ° C. for 1 hour, and then a 0.5 mm sieve mesh (JIS Z8801-1 “Test sieve—Part 1: (Based on “metal mesh sieve”), and the mass% under the sieve was determined. Further, when measuring the mass% of fine particles under 10 μm, the measurement device of the laser diffraction scattering method (MICROTRAC (registered trademark) MT3300, manufactured by Nikkiso Co., Ltd., measurement range: 0.02) is used for the fine powder raw material after drying. ˜1400 μm) was used.

  Here, the iron ore containing at least one or more kinds of fine ores (including fine powder raw materials) is a sintered raw material, and the auxiliary raw materials (component adjusting raw materials) and coagulants are included in this sintered raw material. Whether or not (for example, coke powder or coal powder) is included is arbitrary, and the sintering raw material in the present embodiment refers to a material that does not include quick lime and slaked lime (binder). In addition, when the auxiliary material and the coagulant are included in the sintered raw material, the total amount of the auxiliary material and the coagulant in the sintered material is about 30% by mass or less (the amount of iron ore in the sintered material: The auxiliary raw material and the coagulant may be added to the iron ore so as to be about 70 to 100% by mass of the sintered raw material). It is difficult to improve by the amount.

When the above-mentioned particle size configuration, that is, a fine raw material that is roughly aligned to about 10 μm and under 500 μm is granulated, a space is formed between adjacent raw material particles.
However, as described above, since the fine powder raw material has very few 10 μm-undersized fine particles filling the space, the fine powder raw material is granulated while enclosing the space, and the strength of the granulated product becomes extremely low. For this reason, even if the fine powder raw material is granulated using an adhesive binder such as cellulose, and even if the particles of the adjacent fine powder raw material can be adhered to each other, a space remains in the granulated product. Hard to improve strength.
More generally, the powdered ore is granulated using water, but when high crystal water ore containing 4% by mass or more of crystal water is included in the fine powder material by 30% by mass or more and 60% by mass or less, the pores of the high crystal water ore are included. There is also a problem that water is absorbed and the strength of the granulated material deteriorates (decreases) with time.
In the above situation, it was conceived that the binder used for the granulation of the fine powder raw material is preferably one that can supply fine particles of under 10 μm and can fill the space described above.

In addition, although there exist bentonite, calcium carbonate, etc. in a solid binder, it turned out that it is difficult to disperse | distribute a solid binder uniformly to the above-mentioned fine powder raw material by the grade of a normal kneading | mixing process.
This is because, as described above, the particle size of the fine powder material is almost uniform in a size of about 10 μm over and under 500 μm, and generally the mixing of the raw material by kneading proceeds by having a wide particle size distribution. Even if bentonite, calcium carbonate, or the like that does not atomize or dissolve is added, it is considered that the dispersion does not proceed. From this point of view, it is considered preferable to add fine particles of 10 μm or less by another means.
From the above, the present inventors, as iron ore, when granulating the sintered raw material A group using a fine powder raw material having a particle size of 500 μm under 50% by mass and 10 μm under 5% by mass, As a binder for facilitating kneading and granulation, the inventors came up with quick lime and slaked lime. In addition, the sintering raw material put into a sintering pallet may not knead | mix.

Next, the granulation mechanism by quicklime and slaked lime will be described.
It is considered that quick lime is partly absorbed by digestion (slaked calcification) and atomized by contact with water during kneading and granulation, and easily mixed with the fine powder raw material together with water. In addition, as quicklime, that whose CaO is 84 mass% or more is used abundantly.
Here, a part of the generated slaked lime is easily mixed with the fine powder raw material even by dissolving in water.
In addition, it is the same also when adding slaked lime to a fine powder raw material instead of quick lime or with quick lime, and a part of slaked lime melt | dissolves in water, and it becomes easy to mix uniformly in a fine powder raw material.

Slaked lime produced by digestion of quick lime and slaked lime recrystallized by evaporation of water, etc. are fine particles with a particle size of under 10 μm, and also contain many fine particles of submicron order. This greatly contributes to the improvement of the granulation properties of the raw materials and the strength of the granules.
Therefore, it is important to digest as much quicklime as possible.
From the above, when mixing a difficult-to-granulate fine powder raw material and other raw materials (for example, easy-to-granulate raw material that is easy to granulate), It is also important to add quick lime and slaked lime that have been subjected to a treatment for reducing the amount of lime and to increase the amount of addition.

In addition, calcium carbonate (molecular formula: CaCO ₃ ) contains CaO similarly to quick lime and slaked lime, and has a CaO content of about 56% by mass, and may be referred to as limestone or simply lime. However, calcium carbonate is a chemically stable substance, and digestion due to moisture absorption and dissolution in water hardly occur.
Therefore, calcium carbonate is not contained in the above-mentioned quick lime and slaked lime.
Here, the influence which the kind of binder to add has on the granulation property of a granulated material is demonstrated, referring FIG.

In addition, the test is a fine powder raw material in which a high crystal water ore containing 4% by mass or more of crystal water is blended 0 or more than 0 and 10% by mass or less, and a particle size of 500 μm under is 50% by mass and 10 μm under is 5% by mass After adding 2% by mass of binder (calcium carbonate, slaked lime, quicklime) to (sintering raw material A group) and kneading this with a universal mixer (a vertical mixer that revolves the axis of a rotating stirring blade) And granulated with a drum mixer. Here, as an evaluation standard for addition of the binder, only the hardly granulated fine powder raw material (raw material) to which no binder was added was kneaded with a universal mixer and then granulated with a drum mixer.
The detailed conditions are: moisture: constant in the range of 9 to 12% by mass, kneading: peripheral speed 2.2 m / second, processing time 90 seconds, granulation: peripheral speed 1.0 m / second, processing time 60 seconds. The peripheral speed means the speed of the fastest part of a universal mixer (kneader) and drum mixer (granulator) that rotate (blades, drums, etc.).

Moreover, evaluation was performed in the following procedures.
First, the above granulated fine powder material (2 kg) was dried at 150 ° C. for 1 hour, and then passed through a 0.5 mm sieve mesh (JIS Z8801-1 “Test sieve—Part 1: Metal mesh sieve”). The ratio of 0.5 mm under was defined as the powder rate. The powder ratio was calculated by setting the powder ratio of only the fine powder raw material to which no binder was added to “1.0”.
From FIG. 1, when calcium carbonate is added to the fine powder raw material, the improvement in granulation is small (powder rate: 0.70), whereas when quick lime or slaked lime is added to the fine powder raw material, The present inventors have discovered for the first time that the graininess is remarkably improved (quick lime: 0.41, slaked lime: 0.43).
This is because quick lime is atomized by contact with water, and part of the generated slaked lime (added slaked lime) dissolves in water, making it easy to mix uniformly into the fine powder raw material. This is thought to be due to the great contribution to the improvement of graininess and the strength of the granulated product.

The powder ratio is an average value, and the powder ratio value varied by about 5% when any binder was used.
On the other hand, when the fine powder raw material used in the above test was blended with 30 to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water, the powder rate was deteriorated (increased) as a whole. When calcium carbonate is used as a binder, it shows a variation of about 20 to 30%, whereas when quick lime or slaked lime is used as a binder, it is about 10% smaller than the variation of the powder rate value of calcium carbonate. Met. This is because even if a high crystal water ore that can absorb water into pores after granulation or after granulation is used, if calcium carbonate is used as a binder, the above-mentioned solid cross-linking is not stabilized, while quick lime or slaked lime is used. It was presumed that the above-mentioned solid cross-linking was stable. When digestion by moisture absorption or dissolution in water occurred, it was presumed that the solid cross-linking was relatively stable even if water absorption into the pores occurred.

In view of the above, the present inventors have come up with a pretreatment method for a sintered material that can improve the granulation property of a fine powder material having difficult granulation properties. That is, as the iron ore, a sintering raw material group A (difficult-to-granulate fine powder raw material) using a fine powder raw material having a particle size of 500 μm under with 50% by mass or more and 10 μm under with 5% by mass or less is used under 250 μm. Is a method of granulating by using either 1 or 2 of quicklime and slaked lime having a particle size of 50% by mass or more. Furthermore, as the iron ore, a sintered raw material group B (easy granulating raw material) using a powdered ore having a particle size of 500 μm under less than 50% by weight or 10 μm under over 5% by weight, 250 μm under is 10% by weight to 50%. Either 1 or 2 of quicklime and slaked lime having a particle size of less than mass% can be blended and granulated before or after merging with the granulated material of the sintering raw material group A to obtain a granulated material.
Here, the relationship between the particle sizes of the hardly granulated raw material and the easily granulated raw material is shown in Table 1.

The above-mentioned hardly granulated raw material, that is, a raw material having a particle size in which 500 μm under (−500 μm) is 50% by mass or more and 10 μm under (−10 μm) is 5% by mass or less corresponds to “A” in Table 1. .
On the other hand, easily granulated raw materials which are sintering raw materials obtained by removing the above-mentioned hardly granulated fine powder raw materials from fine ores (iron ores) are listed in “B1”, “B2”, and “B3” in Table 1. Applicable. That is, a raw material having a particle size of 500 μm under less than 50% by mass and 10 μm under 5% by mass or less has a particle size of “B1” in Table 1 with 500 μm under 50% by mass and 10 μm under 5% by mass. The raw materials having a particle size of “B2” in Table 1 with a particle size of 500 μm under less than 50 mass% and 10 μm under 5 mass% correspond to “B3” in Table 1, respectively.
As described above, the sintering raw materials to be granulated can be classified as shown in Table 1.

  The classification of “B1”, “B2”, and “B3” described above can be determined based on the iron ore brand whose particle size distribution is examined, and can be determined based on the particle size distribution even after blending them. Furthermore, since the particle size can be adjusted by sieving or grinding, the classification can be made to the above-mentioned classifications “A”, “B1”, “B2”, and “B3”. Either one (single) or both processing methods of the sieving and pulverization are preferable because the granulation state is stable because the particle size is stable.

Next, the reason why the particle size constitution of the hardly granulated fine powder raw material is defined in the above-described range will be described with reference to FIGS. 2 (A) and 2 (B).
In the test, quick lime (particle size: 250 μm under is less than 50% by mass) is added to the raw material in which high crystal water ore containing 4% by mass or more of crystal water is blended in an amount of 2% by mass. After kneading with the above-mentioned universal mixer, it was granulated with a drum mixer. In this raw material, in the case of FIG. 2A, the mass ratio of 10 μm under in the raw material was fixed to 5 mass%, and the mass ratio of 500 μm under was changed to 20 mass%, 50 mass%, and 75 mass%. In the case of FIG. 2 (B), the mass ratio of the 500 μm under in the raw material was fixed to 50 mass%, and the mass ratio of the 10 μm under mass was changed to 2.5 mass%, 5 mass%, and 8 mass%. Each raw material was used.
The conditions for moisture, kneading, and granulation are the same as the detailed conditions described above.

Moreover, also about evaluation, the above-mentioned ratio of 0.5 mm under was defined as the powder rate. In addition, in the case of FIG. 2 (A), a powder rate is the powder rate of the granulated material which fixed the mass ratio of 10 micrometers under in the raw material to 5 mass%, and made the mass ratio of 500 micrometers under 50 mass%, In the case of FIG. 2 (B), the powder ratio of the granulated product in which the mass ratio of 500 μm under in the raw material is fixed to 50% by mass and the mass ratio of 10 μm under is 5% by mass was calculated as “1”. .
As shown in FIG. 2 (A), when the mass ratio of 10 μm under in the raw material is fixed to 5 mass%, the mass ratio of 500 μm under becomes 50 mass% or more, so that the powder rate of the granulated product is rapidly increased. A tendency to rise was obtained.
Moreover, as shown in FIG. 2 (B), when the mass ratio of 500 μm under in the raw material is fixed to 50% by mass, the mass ratio of 10 μm under becomes 5% by mass or less. A tendency to increase rapidly was obtained.

From the above, in the present invention, as the particle size of the fine powder raw material exhibiting difficult granulation which increases the powder rate of the granulated product, 500 μm under is 50% by mass (further 60% by mass) and 10 μm under is 5% by mass. % (Further 4% by mass) or less. The reason why the upper limit value of 500 μm under is not specified is 100% by mass, and the reason why the lower limit value of 10 μm under is not specified is that 0% by mass may be used.
From the above, it can be seen that if the raw material has a particle size of 500 μm under 50% by mass or more and 10 μm under 5% by mass or less, the powder rate of the granulated product is extremely increased (deteriorated). On the other hand, it can be seen that if the powder ore has a particle size of 500 μm under less than 50% by mass or 10 μm under over 5% by mass, the powder rate is lowered (improved) by a certain level.

Then, the particle size structure of the quicklime added to a fine powder raw material is demonstrated, referring FIG.
The test consists of a hardly granulated fine powder raw material having a particle size of 50 to 50% by mass and 5 to 10% by mass of 10 μm under and containing 30 to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water, The easily granulated raw material having a particle size of less than 50% by mass or less than 5% by mass of 10 μm under which 30 to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water is blended is 250 μm under each. After adding 2% by mass of quick lime having a different mass ratio, the mixture was kneaded with the above-mentioned universal mixer and then granulated with a drum mixer. The conditions for moisture, kneading, and granulation are the same as the detailed conditions described above.
Moreover, also about evaluation, the above-mentioned mass ratio of 0.5 mm under was defined as the powder rate. In addition, the powder rate is calculated as “1” when granulating the easily granulated raw material, when the decrease in the powder rate is not significant, that is, when the mass ratio of 250 μm under in quicklime is 10% by mass, This powder ratio (dotted line in FIG. 3) or less was regarded as acceptable.

As shown in FIG. 3, when granulating the difficult-to-granulate fine powder raw material, by making the mass ratio of 250 μm under in the quicklime 50% by mass or more, the powder ratio of the granulated product is drastically reduced, The powder rate met the acceptance criteria (thick line in FIG. 3).
Moreover, when granulating an easily granulated raw material, since the granulation property is good compared to the difficult granulated fine powder raw material, by making the mass ratio of 250 μm under in quicklime be 10% by mass or more, The powder rate of the granulated product decreased, and the powder rate met the acceptance criteria (thin line in FIG. 3).
In addition, the above-mentioned result showed the same tendency, when using slaked lime instead of quick lime.

From the above, when granulating a difficult-to-granulate fine powder raw material, either 1 or 2 of quick lime and slaked lime having a particle size of 250 mass% or more of 50 mass% (or 60 mass%) or more is used. . Here, the reason why the upper limit value of 250 μm under is not specified is that 100% by mass may be used.
Moreover, when granulating an easily granulated raw material, either 1 or 2 of the quick lime and slaked lime which have a particle size whose 250 micrometers under has a particle size of 10 mass% (further 20 mass%) or more and less than 50 mass% is used.

The reason why the amount of quick lime and slaked lime 250 μm under used in the easily granulated raw material was set to less than 50% by mass was that the powder rate could be suppressed, and the above-mentioned hardly granulated fine powder raw material was granulated. In doing so, it is possible to use the remaining quicklime and slaked lime used for the granulation of the difficult-to-granulate fine powder raw material for the granulation of the easily granulated raw material, and to effectively use the quicklime and slaked lime.
Thereby, quick lime and slaked lime can be used for granulation of an easily granulated raw material in a relatively coarse state without making all of them fine, so that the production cost can be reduced and it is economical.

For the granulation treatment of the above-mentioned difficult-to-granulate fine powder raw material (hereinafter also referred to as sintering raw material A group) and easy-to-granulate raw material (hereinafter also referred to as sintered raw material B group), stirring such as an Eirich mixer is used. Or a kneading machine such as a Redige mixer, or a rolling granulator such as a drum mixer or a dish granulator may be used.
In addition, the drum mixer, which is a rolling granulator, can add a coagulating material and auxiliary materials from the middle of the granulation, and suppresses the flocculation of the coagulating material and sintering by local concentration of the auxiliary materials. It is preferable because the melting of the raw material at the time can be controlled.

Here, an example of the granulation process of the above-described sintered raw material A group and further the sintered raw material B group is shown in FIGS. 4 (A) to 4 (E).
As shown in FIG. 4 (A), the sintered raw material group A and quicklime (and / or slaked lime, the same applies hereinafter) are agitated with a stirrer or kneaded with a kneader to obtain a granulated product. Is supplied to the sintering machine.
Moreover, as shown to FIG. 4 (B), the sintering raw material A group and quicklime are granulated with a rolling granulator, and the obtained granulated material is supplied to a sintering machine.
And as shown in FIG.4 (C), the sintering raw material A group and quicklime are stirred with a stirrer, or kneaded with a kneader, and further granulated with a rolling granulator, The obtained granulated material is supplied to a sintering machine.

Further, as shown in FIG. 4 (D), the granulation treatment of the sintering raw material group A and the granulation treatment of the sintering raw material group B by the above-described method are performed in parallel, and obtained by both granulation treatments. The granulated product can be merged and the granulated product can be supplied to the sintering machine (granulation treatment of the sintered raw material B group is performed before joining with the granulated product of the sintered raw material A group. ). In addition, the granulation process of the sintering raw material B group can be performed by the same method as the granulation process of the above-described sintering raw material group A (that is, for the sintering raw material group B and quicklime (and / or slaked lime), 4 (A) to 4 (C) are performed).
Here, the merging of the granulated product of the sintered raw material group A and the granulated product of the sintered raw material group B may, for example, supply both granulated products on a belt conveyor (conveying means), Moreover, you may mix each granulated material with a drum mixer.

Further, as shown in FIG. 4 (E), the granulated product of the sintering raw material A group obtained by the above-described method is supplied to the sintering raw material B group to be merged, and the granulation of the sintering raw material A group is performed. It is also possible to supply the resulting granulated product to a sintering machine by subjecting the material and the sintered raw material B group to the granulation treatment of the sintered raw material B group described above. The granulation treatment of the raw material B group is performed after merging with the granulated product of the sintered raw material A group). That is, the process of FIG. 4 (A)-(C) is performed with respect to the granulated material of the sintering raw material A group, the sintering raw material B group, and quicklime (and / or slaked lime).
This is because when the granulated product of the sintering raw material A group is merged with the sintered raw material B group alone, the granulated product of the sintering raw material A group is sintered. This is because granulation of the raw material B group proceeds and a more suitable granulation effect is obtained.

In addition, after granulating the sintering raw material group A and the sintering raw material group B described above, when charging into the sintering machine, the coagulant is also charged into the sintering machine (for example, in the sintering machine). The outer shell is about 3 to 6% by mass with respect to all the sintered raw materials to be charged).
As described above, since the coagulation material may be finally charged into the sintering machine, it can be added to one or both of the sintering raw material group A and the sintering raw material group B. It is preferable to add to the group. This is because adding the coagulant to the sintering raw material B group can suppress the burying of the coagulating material and contribute to the sintering phenomenon, so that the proportion of the coagulating material added to the sintering raw material B group increases. This is because an inhibitory effect is obtained.
Thereby, it can contribute to the reduction of the usage-amount of a condensing material, and the improvement of a sintered ore quality.

Next, examples carried out for confirming the effects of the present invention will be described.
The test was performed by adding 2% by mass of quick lime as a raw material to the raw material, kneading it with the above-mentioned universal mixer, and granulating it with a drum mixer. The conditions for moisture, kneading, and granulation are the same as the detailed conditions described above.
As this raw material, a raw material having a particle size shown in Table 2 was used. Each ore type listed in Table 2 corresponds to “A”, “B1”, “B2”, and “B3” listed in Table 1, respectively. The granular fine powder material (fine powder raw material containing 30 to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water), and “Group B” means an easily granulated raw material.
Moreover, the quicklime (CR and CF) which has the particle size shown in Table 3 was used for the quicklime added to a raw material.

The evaluation was performed by defining the above-mentioned ratio of 0.5 mm under as the powder rate.
Here, Table 4 shows test conditions and test results.

In Table 4, line 1 and line 2 are separate lines for granulating the raw material and are arranged in parallel. That is, in the case of granulating the difficult-to-granulate fine powder raw material in line 1 and the easy-to-granulate raw material in line 2, respectively, This means that the grain processing is performed in parallel (see FIG. 4D).
Further, Conventional Example 1 in Table 4 is a result of using relatively coarse-grained quick lime “CR” when granulating “B3” on line 1 and “B2” on line 2 respectively. In the conventional example 2, when “B1” is granulated in each of the lines 1 and 2, the relatively coarse-grained quick lime “CR” is used in the line 1, and the quick lime is not used in the line 2. is there.

And comprehensive evaluation was performed using the powder rate of each raw material granulated by the lines 1 and 2 of the prior art examples 1 and 2. FIG. In the comprehensive evaluation column, “○” indicates that the actual machine can be used, and “×” indicates that the actual machine cannot be used. "
Here, the powder ratio of each raw material granulated in lines 1 and 2 of Conventional Examples 1 and 2 increases in the order of Base 1, Base 3, Base 2, and Base 4, and Comparative Examples 1, 2 and Examples In the evaluation of the powder ratio of 1 to 7, the case where the powder ratio is higher than any of the bases 1 to 4 is “X”, the case where the powder ratio is lower than any is “◯”, and “○” or “×” When it was not applicable, the powder ratio was equivalent and “△” was assigned.

As shown in Table 4, in Comparative Example 1, quick lime “CR” was added to the hardly granulated fine powder raw material “A” in line 1, and quick lime “CR” was added to easy granulated raw material “B1” in line 2. It is a result at the time of adding and granulating each.
In line 1, since relatively coarse-grained quick lime “CR” was used for granulation of the difficult-to-granulate fine powder raw material, the granulation property was deteriorated and the powder rate was worse than those of the bases 1 to 4 (×). Moreover, since the line 2 is the same conditions as the line 1 of the prior art example 2, the powder rate was comparable to the base 3 ((triangle | delta)).
Therefore, it was not able to be adopted with an actual machine (overall evaluation: x).
In addition, in the comparative example 1 described above, when the amount of quicklime added to the raw material is increased from 2% by mass to 6% by mass or more (outer coating), the evaluation of the powder rate is changed from “×” to “Δ” to “Δ”. However, since the normal addition amount of quick lime is 5% by mass or less (the lower limit is about 0.1% by mass), the evaluation of the powder rate is “x”, and the overall evaluation is also “x”.

Comparative Example 2 uses a fine powder raw material “A ^* ” in which high crystal water ore containing 4% by mass or more of crystal water is blended 0 or more than 0% by mass and less than 10% by mass as the hardly granulated fine powder raw material. This is a result when granulated only in line 1 by adding quick lime “CR” to raw material “A ^* ”.
As described above, since the blending ratio of the high crystal water ore is low, it is considered that the granulation property is improved as compared with Comparative Example 1, but the influence of the particle size distribution of the fine raw material “A ^* ” and the relatively coarse particles The powder rate was worse than that of Bases 1 to 4 due to the use of quick lime “CR” (×).
Therefore, it was not able to be adopted with an actual machine (overall evaluation: x).

On the other hand, Examples 1-4 are the results at the time of granulating by adding quick lime "CF" to the hardly granulated fine powder raw material "A" in line 1. In addition, the lines 2 of Examples 1, 2, and 4 are respectively granulated by adding quick lime “CF” to the easily granulated raw materials “B1”, “B2”, or “B3”. Line 2 was granulated without adding quicklime to the easily granulated raw material “B1”.
In line 1, since relatively fine-grained quick lime “CF” was used for granulation of the difficult-to-granulate fine powder raw material, the granulation property was improved and the powder rate was lower than the bases 1 to 4 (◯). . Moreover, in the line 2 of Examples 1, 2, and 4, since the comparatively fine grain quick lime "CF" was used for granulation of an easily granulated raw material, granulation property became favorable and the powder rate was base 1 It was lower than ~ 4 (◯). And since the line 2 of Example 3 is the same conditions as the line 2 of the prior art example 2, the powder rate was comparable as the base 4 ((triangle | delta)).
Therefore, it was able to be adopted with the actual machine (overall evaluation: ○).

In Examples 5 to 7, quick lime “CF” is added to the hardly granulated fine powder raw material “A” in line 1, and easily granulated raw material “B1”, “B2”, or “B3” in line 2. It is a result at the time of adding quick lime "CR" to and granulating each.
In line 1, since relatively fine-grained quick lime “CF” was used for granulation of the difficult-to-granulate fine powder raw material, the granulation property was improved and the powder rate was lower than the bases 1 to 4 (◯). . Moreover, since the line 2 is the same conditions as the lines 1 and 2 of the prior art example 1 and the line 1 of the prior art example 2, the powder rate was comparable to the bases 1 to 3 (Δ).
Therefore, it was able to be adopted with the actual machine (overall evaluation: ○).
In Examples 5-7, quick lime in a coarse state can be used for granulation of an easily granulated raw material without carrying out a fine granulation treatment, so that both improvement of the whole powder rate and cost reduction of quick lime can be achieved. It was.
The above test results showed the same tendency when using slaked lime instead of quick lime.

Moreover, about Example 6 shown in Table 4, the granulated material which added the coagulant was produced and sintering productivity was examined.
In the test, 50% by mass of the granulated product obtained by adding quick lime “CF” to the hardly granulated fine powder raw material “A” and 50% by mass of the granulated product obtained by adding quick lime “CR” to the easily granulated raw material “B2”. Was loaded into a laboratory sintering machine (80 kg firing) with a suction pressure of 1000 mmAq (9.8 kPa) and sintered. The agglomerated material is based on the premise that 4% by mass is added to the total amount of the hardly granulated raw material “A” and the easily granulated raw material “B2” as an outer shell. Various addition amounts to “A” and the easily granulated raw material “B2” were changed.

The test results described above are shown in FIG.
The horizontal axis in FIG. 5 indicates the amount of the coagulant added to the easily granulated raw material “B2”, and the horizontal axis “0% by mass” indicates the total (4% by mass of the above-described outer coating). When the material is added to the difficult-to-granulate fine powder raw material “A” and granulated, the horizontal axis “100% by mass” is granulated by adding all the agglomerated materials to the easily granulated raw material “B2”. Each case is shown. The vertical axis in FIG. 5 indicates the sintering productivity, and the sintering productivity when all the agglomerated materials are added to the hardly granulated fine powder raw material “A” and granulated is “1.00”. " The sintering productivity is represented by the product of the firing rate and the yield. The unit of the firing rate is (kg / min), and the unit of the yield is (mass%).

As shown in FIG. 5, as the amount of the coagulant added to the readily granulated raw material “B2” increases from 0% by mass, the sintering productivity increases at a constant gradient, and 30% by mass of the whole is obtained. When added, the sintering productivity was 1.05. The addition amount of the coagulant further increased from 30% by mass, and although the gradient slightly changed, the sintering productivity increased. When 60% by mass was added, the sintering productivity became 1.08. When the addition amount of the coagulant was further increased from 60% by mass, the effect on the sintering productivity was almost saturated, but gradually increased. When 100% by mass was added, the sintering productivity was increased to 1.09.
In addition, the same tendency as this test result was obtained also when using slaked lime instead of quick lime.

  From the above, by using the sintering raw material pretreatment method of the present invention, it is possible to suppress the increase in the amount of binder used, improve the granulating property of the sintering raw material, and enable granulation of the fine powder raw material. In addition, it was confirmed that the granulated product can be used for the production of sintered ore by suppressing the collapse of the granulated product.

  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 in which the sintering raw material pretreatment method of the present invention is configured by combining some or all of the above-described embodiments and modifications is also included in the scope of the right of the present invention.

Claims (3)

As the iron ore, a sintered raw material A group using a fine raw material that is a fine ore having a particle size of 500 μm under 50 μm or more and 10 μm under 5% by mass, quick lime having a particle size of 250 μm under 50 μ% or more and A pretreatment method for a sintering raw material, characterized by granulating a slaked lime using any one or two of slaked lime. In the pretreatment method of the sintering raw material according to claim 1, 250 μm under is present in the sintering raw material B group using a fine ore having a particle size of 500 μm under less than 50 mass% or 10 μm under over 5 mass% as iron ore. Mixing either 1 or 2 of quicklime and slaked lime having a particle size of 10% by mass or more and less than 50% by mass, granulating before or after merging with the granulated product of the sintered raw material A group, A pretreatment method for a sintering raw material characterized by: 3. The pretreatment method for a sintering material according to claim 2, wherein at least a coagulant that generates heat by oxidation is added to the sintering material B group.

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