JP2014051702A - Pretreatment method of sintering raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment method of a sintering raw material capable of granulation of a fine powder raw material having granulation difficulty by suppressing increase of a used amount of a binder and improving granulating property of the sintering raw material, further capable of being used for manufacturing a sintered ore by suppressing collapse of a granulated material.SOLUTION: A pretreatment method of a sintering raw material includes: combining an agitated product obtained from a line A of charging a sintering raw material A group using a fine powder raw material of a fine ore having particle size of under 500 μm with 50 mass% or more and under 10 μm with 5 mass% or less in terms of an iron ore, and a binder Xcontaining a caustic lime and/or a hydrated lime into an agitator and agitating it with a peripheral velocity of agitating blade of 2 m/sec. or more, and a supplied product from a line B supplying a sintering raw material B group and the binder Xcontaining the caustic lime and/or the hydrated lime; and further granulating the combined mixture to obtain a granulated material. A value obtained by dividing binder concentration Cof the line A by binder concentration Cof the line B is 1 or more, and binder concentration Cis over 0.2 mass%.

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, fine powder raw material) has increased, and let this fine powder raw material be granulated by conventional methods. 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 pretreatment method of the sintering raw material according to the present invention that meets the above-mentioned object is a sintering raw material A that uses 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 as iron ore. _A binder XA consisting of either 1 or 2 of quick lime and slaked lime having a particle size of 50% by mass or more with 1.0 mm under is charged in a stirrer, and the peripheral speed of the stirrer blades of the stirrer is 2 m Line A for stirring at a rate of at least / second;
Binder X consisting of sintered raw material B group using powder ore of the same particle size or different particle size as the iron ore, and any one or two of quick lime and slaked lime with a 1.0 mm under particle size of 50% by mass or more Line B to which _B is supplied,
After the agitation product obtained in the line A and the supply material in the line B are merged, a pretreatment method of a sintering raw material that is further granulated to obtain a granulated product,
The binder concentration C _A is the percentage of the sintered raw material group A quantity alpha _A and the binder X the quick lime converted amount to the total amount T _A with quicklime equivalent amount beta _A of _A beta _A, the sintered material group B quantities alpha _B and the binder X _B quicklime equivalent amount beta _B and the total amount T the quicklime equivalent amount beta binder concentration C _B in a value obtained by dividing 1 super city is the ratio of _B to _B of, and the binder concentration C _B is more than 0.2% by mass.

  In the sintering raw material pretreatment method according to the present invention, it is preferable that a coagulant is blended at least in the line B.

The sintering raw material pretreatment method according to the present invention stirs a sintering raw material A group using a fine powder raw material as iron ore and quick lime (binder X _A ) having a particle size of 1.0 mm under 50% by mass or more. Since it is charged into the machine and stirred at a peripheral speed of the stirring blade of 2 m / sec or more, digestion (slaked calcification) of the added quicklime is promoted, atomized, and easily mixed with the fine powder raw material together with water. Here, a part of the generated slaked lime is easily mixed with the fine powder raw material even by dissolving in water.
The same applies to the case where slaked lime (binder X _A ) is added to the fine powder raw material instead of or together with quick lime, and a portion of the slaked lime is dissolved in water and uniformly mixed in the fine powder raw material. It becomes easy.
This line A agitation (sintered raw material A group and binder X _A ) is joined with the supply of line B (sintered raw material B group and binder X _B having a 1.0 mm under particle size of 50% by mass or more). After granulation, the value obtained by dividing the binder concentration C _A of the line _A by the binder concentration C _B of the line B is more than 1, and the binder concentration C _B is more than 0.2% by mass. Without significantly increasing the amount of lime and slaked lime), the granulating properties can be improved and the sintered raw material group A can be granulated. Can be manufactured.
This is because when only the sintered raw material group A having a particle size composition of about 10 μm over 500 μm is granulated, a space is formed inside the granulated product, so the peripheral speed of the stirring blade of the stirrer is reduced. By using quick lime or slaked lime having the above-mentioned particle size and the above-described particle size, these are filled in the space inside the granulated product (inside the stirred product).
In addition, the above-mentioned maramamba ore described in Patent Document 1 is a sintering raw material having a large number of fine particles under 10 μm, and does not exhibit the difficult granulation property of the above-described sintering raw material group A.

Further, when a coagulant is blended at least in the line B, the sintering phenomenon (oxidation exothermic phenomenon) can be promoted, so that the amount of 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 condensate can be suppressed by blending the condensate into the line 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 1.0 mm under in quicklime has on the powder rate after granulation. Line A, quick lime concentration of B C _A, the ratio of C _B is a graph showing the effect on granulation after flour ratio. Lime concentration C _A of the line A is a graph showing the effect on the Sintering productivity improvement. It is a graph which shows the influence which the processing amount of the line A with respect to the total processing amount of the lines A and B exerts on sintering productivity. It is a graph which shows the influence which the addition ratio of the coagulating material to the line B 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 was found that this feature can be obtained by repeating, for example, iron ore crushing treatment and water specific gravity separation processing. 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 contain quicklime or 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 the particles of the adjacent fine powder raw material can be adhered to each other, a space remains inside 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 with a normal stirring (kneading | mixing) process grade.
This is because, as described above, the particle size of the fine powder raw material is almost uniform in the size of about 10 μm over and under 500 μm, and generally the mixing of the raw material by stirring proceeds with 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 stirring and granulation, quick lime and slaked lime were conceived. In addition, the sintering raw material put into a sintering pallet may not be stirred.

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 stirring 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.

Calcium carbonate (molecular formula: CaCO ₃ ) contains CaO in the same manner as quicklime, 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 quicklime.
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, quicklime, slaked lime) to (sintered raw material group A) and stirring 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 adding a binder, only a hardly granulated fine powder raw material (raw material) to which a binder was not added was stirred with a universal mixer and then granulated with a drum mixer.
Detailed conditions are constant within a range of moisture: 9 to 12% by mass, stirring (kneading): peripheral speed 2.0 m / second, processing time 90 seconds, granulation: peripheral speed 1.0 m / second, processing time 60 seconds, It is. The peripheral speed means the speed of the fastest part of a universal mixer (stirrer) 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: 0.75), 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: 0.45, slaked lime: 0.48).
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, a sintered raw material group A (non-granulated fine powder raw material) using a fine powder raw material having a particle size of 500 μm under 50 μ% or more and 10 μm under 5 μ% or less as iron ore, and 1.0 mm under line but the binder X _a consisting of either 1 or 2 of quicklime and hydrated lime having 50 mass% of the particle size were charged into a stirrer, and stirred with a peripheral speed of the stirring blade of the stirrer than 2m / sec A and a sintering raw material B group (a difficult-to-granulate fine powder material or an easily-granulated material) using powder ore of the same or different particle size as the above-mentioned ore as iron ore, and 1.0 mm under is 50% by mass or more of and a line B which is either 1 or 2 comprising a binder X _B of quicklime and slaked lime is supplied with a particle size, stirring mixture obtained in line a (sintering material group a and the binder X _a), Line B Things After merging the (sintering raw material group B Binder X _B) and a pre-processing method of the sintering material further granulated to granules, the amount of the sintering raw material group A alpha _A and the binder the X _a total amount T _a binder concentration C _a is the percentage of quick lime equivalent amount beta _a for the quicklime equivalent amount beta _a of the quick lime converted amount beta _B amounts alpha _B and binder X _B of the sintering material group B the total amount T 1 super cities value obtained by dividing the binder concentration C _B is the ratio of the quick lime equivalent amount beta _B to _B of, and a method of more than 0.2 mass% of the binder concentration C _B.

The quick lime described above is manufactured by thermal decomposition in which calcium carbonate, which is a main component such as limestone, is heated to about 1100 ° C. to release carbon dioxide, and is then subjected to fine granulation by crushing to obtain a predetermined particle size. .
However, when reducing the particle size of quicklime, as described above, it is necessary to carry out a fine graining process, leading to an increase in manufacturing cost. It is preferable that the coarse particle state, for example, 250 μm under is 0% by mass or more than 0% by mass and less than 50% by mass (further 40% by mass or less). Thereby, since the refinement | miniaturization process of quicklime can be abbreviate | omitted, reduction of manufacturing cost can be aimed at and it is economical.

Moreover, when stirring the above-mentioned quick lime and the sintering raw material using a stirrer, the peripheral speed of the stirring blade is set to 2 m / second (more preferably 3 m / second) or more, so that water and quick lime are mixed. The contact rate per unit time can be increased, atomization of quick lime is promoted by slaked calcification, and the generated slaked lime is dispersed throughout the sintered raw material (macro) and adhered to the surface of each sintered raw material as much as possible (micro) Can be dispersed). Moreover, when stirring slaked lime and a sintering raw material using a stirrer, the peripheral speed of the stirring blade is set to 2 m / second (more preferably 3 m / second) or more, so that the slaked lime is converted into the entire sintered raw material ( Macro) and can adhere to the particle surface of each sintering raw material as much as possible (dispersed microscopically).
Therefore, the stirrer is not particularly limited as long as the peripheral speed of the stirring blade can be 2 m / second or more, and for example, the above-described universal mixer can be used. Although the upper limit value of the peripheral speed of the stirring blade is not particularly limited from the above description, it is, for example, about 35 m / second in consideration of a stirrer generally used in the world. Moreover, the diameter of a stirring blade is about 0.1-1.5 m including what is used in a laboratory. The diameter of the stirring blade means the outer diameter of the stirring blade during rotation. For example, when a plurality of blades are provided in the circumferential direction of the rotating shaft, the stirring blade is provided on both sides of the rotating shaft. It means the distance between the tips of the blades.
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: 1.0 mm under is less than 50% by mass) is added to a raw material in which 30% to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water is added, This was stirred with the above-mentioned universal mixer and then 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, stirring, 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, To an 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 1.0 mm each. Quick lime with a different mass ratio of under (250 μm under is constant at 0% by mass) was added 2% by mass on the outside and stirred with the above-mentioned universal mixer (with a stirring speed of 1.0 m / sec. 0 m / sec) or without agitation (without a stirrer) and granulated with a drum mixer. The conditions for moisture 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 ratio refers to the case where the decrease in the powder ratio is not significant in the granulation of the easily granulated raw material, that is, the case where the mass ratio of 1.0 mm under in quicklime is 10 mass% without a stirrer. 1 ", and 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, the stirring speed is 2.0 m / sec or more, and the mass ratio of 1.0 mm under in quicklime is 50 mass% or more. The powder rate of the granulated material was drastically decreased, and 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 with a difficult-to-granulate fine powder raw material, the mass ratio of 1.0 mm under in quicklime is made 10 mass% or more. Thus, the powder rate of the granulated product decreased, and the powder rate met the criteria for acceptance (thin line in FIG. 3).
From the above, when stirring the difficult-to-granulate fine powder raw material in line A, the stirring speed is set to 2.0 m / sec or more, and the 1.0 mm under is 50% by mass (or 60% by mass) or more. We decided to use quicklime that we have. Here, the reason why the upper limit value of 1.0 mm under is not specified is that 100% by mass may be used.
The above-mentioned result showed the same tendency also when using slaked lime instead of quick lime.

As described above, although the hardly granulated fine powder raw material is used as the sintering raw material to be stirred in line A, the sintering raw material supplied to line B is not limited. This is because either the hardly granulated fine powder material (A in Table 1) or the easily granulated material (B1 to B3 in Table 1) may be used.
In line A, as described above, since the peripheral speed of the stirring blade of the stirrer is 2.0 m / second or more, digestion (slaked calcification) of the added quicklime is promoted, atomized, and finely divided with water. It becomes easy to mix evenly. Here, a part of the generated slaked lime is easily mixed with the fine powder raw material even by dissolving in water. Moreover, 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.
Thus, the binder X _A which is easily mixed uniformly into fine material, for supplying with pulverized raw material (as stirring was) line B, not in line B stirrer (mixer) Required.

The agitated product (difficult-to-granulate fine powder raw material and binder X _A ) obtained in the above-described line A and the supply of line B (refractory-granulated fine powder raw material or easily granulated raw material and binder X _B ) are merged. Then, it is further granulated to obtain a granulated product. In addition, for the granulation treatment after the mixture of the agitated material and the feed, a rolling granulator (granulator) such as a drum mixer or a dish granulator can be used. A stirrer (kneader) such as a Redige mixer may be used.
In the production of the granulated material described above, since it is necessary to suppress the increase in the amount of binder used, the total amount of binder used in line A and line B is used in order to demonstrate the ability of the binder more effectively. The amount of binder used in line A and line B is changed to be constant. For this reason, the particle size constitution of the binder used in the line B is also the same as the particle size constitution of the binder used in the line A described above. The binder used in the lines A and B may be the same as or different from each other as long as the above particle size range is satisfied.
Here, referring to FIG. 4, the effect of the value obtained by dividing the quick lime concentration C _A of line _A by the quick lime concentration C _B of line B, that is, the ratio (C _A / C _B ), on the powder rate after granulation will be described. While explaining.

In this test, the processing amount of line A and line B is 1: 1 (same amount), the quick lime concentration is 2% by mass (constant) in the entire processing amount of lines A and B, and quick lime is distributed to lines A and B. After changing the quicklime concentration of line A and B variously and producing the agitated material in line A, the granulated material was produced in line B. In addition, in the sintering raw material A group and the sintering raw material B group used in each of the lines A and B, a hardly granulated fine powder containing 30 to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water. Raw materials (particle size: 500 μm under 50% by mass and 10 μm under 5% by mass) were used, and quick lime (particle size: 1.0 mm under 50% by mass or more) was used as the binder. For this reason, the binder concentrations C _A and C _B are also described herein as quick lime concentrations C _A and C _B.
Moreover, the manufacturing conditions of the granulated product are constant within a range of moisture: 9 to 12% by mass, stirring of the line A: peripheral speed 2.0 m / second, treatment time 90 seconds, granulation of the line B: peripheral speed 1. It was set to 0 m / second and a processing time of 60 seconds.
Here, the throughput of the line A, which means the total amount T _A of the sintering raw material amount of group A alpha _A and the binder X quicklime equivalent amount of _A beta _A used in the line A (processing of line B The same).

Further, the binder concentration C _A of the line A, the fraction of quicklime equivalent amount beta _A with respect to the processing of the line A, (also binder concentration C _B line B) the following formula.
(Binder concentration C _A )
= (Binder X _A quick lime equivalent β _A ) / (Line A throughput) × 100 (1)
The above-mentioned quick lime converted amount beta _A, when using quick lime (CaO) as the binder _{X A} is the mass of CaO is quicklime equivalent amount beta _A, using hydrated lime (Ca _{(OH) 2)} as a binder _{X A} If you want, Ca _(OH) of CaO in ₂ mass becomes quicklime equivalent amount beta _a. The mass of the binder X _A is the mass of moisture is measured in a state of 0 mass% (binder X _B as well).
Here, the binder concentration in the granulation product obtained (Binder X _A to the mass of _granules, the ratio of the total mass of the X _B), for example, 0.5 to 6 wt%, a.

As described above, when the quick lime concentration in the total processing amount of the lines A and B is fixed to 2% by mass and the quick lime is distributed to the lines A and B, the quick lime concentration CB of the line _B is set to 4.0% by mass, 3.0 mass%, 2.0 mass%, 1.0 mass%, 0.6 mass%, 0.4 mass%, 0.2 mass%, 0.1 mass%, corresponding to this , quicklime concentration _{C a} of the line a is 0 wt%, 1.0 wt%, 2.0 wt%, 3.0 wt%, 3.4 wt%, 3.6 wt%, 3.8 wt%, 3.9% by mass.
Thus, by distributing quick lime to lines A and B, the quick lime concentrations C _A and C _B of lines A and B exceed 2.0 mass% because the quick lime concentrations of lines A and B are as follows: By being expressed by a formula.
(Binder concentration of lines A and B as a whole)
= {(Quick lime equivalent amount of binder X _A β _A ) + (Binder X _B quick lime equivalent amount β _B )}
/ {(Processing amount of line A) + (processing amount of line B)} × 100 (2)

The test results of FIG. 4 obtained under the above test conditions will be described.
As shown in FIG. 4, (in accordance with increasing the C A _/ C _B) in accordance with increasing lime concentration C _A of the line A, the powder rate decreased. This is due to the following reason.
In line A, since the stirring is performed at a peripheral speed of 2.0 m / sec, digestion (slaked calcification) of the added quicklime is promoted, atomized, and easily mixed with the fine powder raw material together with water. 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.
Thus, since what became easy to mix uniformly with a fine powder raw material is supplied to the supply of the line B, since granulation property improves rather than the case where quick lime and slaked lime are added directly to the line B. Conceivable.

On the other hand, less 0.2 wt% quick lime concentration _{C B} of the line B _(C A / _{C B} 3.8 / 0.2 = 19.0 or more) comes to (the quick lime concentration _{C A} of the line A is high) The granulation property was greatly reduced, and the powder rate was increased (1.0 or more). This is because quick lime and slaked lime that have been digested and atomized in line A are supplied in the form of a mixture with the fine powder raw material in line A, and thus it takes a long time to be uniformly mixed with the fine powder raw material in line B. This is probably because of this.
In the above test, the hardly granulated fine powder raw material was used as the sintering raw material of line B, but the same result was obtained when the easily granulated raw material was used.
Moreover, in the above-described test, the case where the quick lime concentration in the entire processing amount of the lines A and B was fixed to 2% by mass was explained, but as described above, the binder concentration in the obtained granulated product was set to 0.00. The same tendency was obtained also when it changed in the range of 5-6 mass%.

Here, the difference between the test results of the present invention and the contents described in Patent Document 1 (Japanese Patent Laid-Open No. 5-9601) will be described in more detail with reference to FIG.
In FIG. 5, the test results of the present invention are indicated by solid lines, and the contents described in Patent Document 1 are indicated by dotted lines.
The test conditions in FIG. 5 are the same as those in FIG.
The vertical axis of FIG. 5, the sintering productivity when the quick lime concentration C _A of the line A was 0% by weight as "1.0", is represented by percentage improvement (improvement rate). 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%).

The present invention and Patent Document 1 are common in that a part of the raw material to be treated with a drum mixer is treated with a stirrer and quick lime is used in both lines.
Moreover, in patent document 1, in the state which made quick lime constant 2% in total, when not using quick lime for the line A which uses a stirrer, compared with the case where it puts the whole quantity, the line A which uses a stirrer, It has been reported that productivity is improved when the same amount is put in other lines B (that is, the dotted line in FIG. 5). In Patent Document 1, both lines are described as 1% in FIG. 4 and the total is 2%, and the meaning of the sentence is unclear (the above formula (1), Here, it was estimated that 2% was mixed in both lines from the description that the total 2% was constant in the specification.

However, when a raw material having a unique particle size distribution is used as in the present invention, the method of using quick lime is similar to Patent Document 1, even if the quick lime is in a constant state of 2%. Rather than putting the same amount in line B, as shown in FIG. 5, by putting it in excess in line A (C _A / C _B > 1), quick lime or slaked lime dissolved in water is granulated in line B The inventors have discovered for the first time that the performance is improved. In addition, when making granulation property equivalent, the usage-amount of quicklime can be reduced.
From the above, to reduce the Konaritsu, to improve the sintering productivity improvement, the ratio of Baidan concentration C _B of the binder concentration C _A and line B of the line A of (C A _{/ C B)} 1 than And the binder concentration C _B was more than 0.2% by mass.
In addition, the ratio (C _A / C _B ) of the binder concentration C _A and C _B is 1.1 or more, more preferably 1.2 or more, and the binder concentration C _B is 0.3 mass% or more. Is preferably 0.4% by mass or more because the granulation property can be further improved.

Then, the total processing volume throughput of the line A with respect to (the total amount T _A and the total amount T sum of _B) (total amount T _A) is an influence on the Sintering productivity lines A and B, and FIG. 6 The description will be given with reference.
In this test, the processing amount of line A and line B was changed, and the ratio of quick lime concentrations C _A and C _B (C _A / C _B ) of lines A and B was fixed to two types. 5 (FIG. 4) was performed under substantially the same test conditions. In addition, the ratio (C _A / C _B ) of the quick lime concentrations C _A and C _B of the lines A and B is shown for two types when it is 1 (■ mark) and 2 (♦ mark). .
Moreover, the vertical axis | shaft of FIG. 6 is the parameter | index similar to the sintering productivity described in FIG. 5, and the ratio (C _A / C _B ) of the quick lime concentrations C _A and C _B of the lines A and B is 1. The case is expressed as an improvement rate with “1.0”.

As is clear from FIG. 6, when the ratio (C _A / C _B ) of the quick lime concentrations C _A and C _B of the lines A and B is more than 1 (here 2), a part of the total processing amount is the line A It was found that the sintering productivity can be improved (sintering productivity: more than 1.000) by processing with (the processing amount of line A with respect to the entire processing amount of lines A and B is more than 0% by mass). (Refer to the dotted line in FIG. 6).
In particular, the improvement rate tended to increase as the throughput of line A with respect to the overall throughput of lines A and B was increased from 10 mass% to 50 mass%, and further to 90 mass%. In addition, when the processing amount of the line A exceeded 90 mass%, the increase tendency of the improvement rate became small.
From the above results, it is preferable that the processing amount of the line A with respect to the total processing amount of the lines A and B is 10% by mass or more and 90% by mass or less.

In addition, the agitation material obtained in the above-mentioned line A and the supply material in the line B are merged and further granulated to form a granulated material. It is charged in the kneading machine (for example, about 3 to 6% by mass with respect to all the sintering raw materials charged in the sintering machine).
As described above, since the coagulant may be finally charged into the sintering machine, it can be added (mixed) to one or both of line A and line B. preferable. This is because when a coagulant is added to the line A where stirring is essential, there is a possibility that the sintering raw material adheres around the coagulant and inhibits the oxidation heat generation phenomenon. Therefore, the addition of the coagulant to the line B can suppress the burying of the coagulant and contribute to the sintering phenomenon, so that as the proportion of the coagulant added to the line B is increased, the effect of suppressing the burial is obtained. It is.

Here, the result of having produced the granulated material which added the coagulating material and examined sintering productivity is demonstrated.
In the test, the stirrer obtained in line A (50% by weight of stirrer stirred and blended with the hardly granulated raw material “A” shown in Table 1 and quick lime) and the feed in line B (in Table 1) After blending the easily granulated raw material “B3” and the mixture containing quick lime (50% by mass) to form a granulated product, it is placed in a laboratory sintering machine (80 kg firing) with a suction pressure of 1000 mmAq (9.8 kPa). It was carried out by charging and sintering. It is to be noted that the coagulant is added to line A and line B 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 “B3”. The addition amount of was variously changed.

The test results described above are shown in FIG.
The horizontal axis in FIG. 7 indicates the amount of the coagulant added to the line B, and the horizontal axis “0% by mass” indicates that all the coagulant (4% by mass of the above-mentioned outer coating) is added to the line A. The horizontal axis “100% by mass” indicates the case where all the aggregates are added to the line B and granulated. The vertical axis in FIG. 7 indicates the above-described sintering productivity, and the sintering productivity when all the aggregates are added to the line A and granulated is evaluated as “1.00”. ing.

As shown in FIG. 7, the amount of the coagulant added to the line B increases from 0% by mass, and the sintering productivity increases at a constant gradient. The property was 1.03. 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 1.05. 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, and when 100% by mass was added, the sintering productivity increased to 1.06.
Thereby, it turns out that it can contribute to the reduction of the usage-amount of a coagulant, and the improvement of a sintered ore quality.

  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 (2)

A sintered raw material A group using a fine powder raw material that is a fine ore having a particle size of 50% by mass or more and 10 μm under 5% by mass or less as iron ore, and quick lime having a particle size of 1.0mm under and 50% by mass or more and a binder X _a consisting of either 1 or 2 of slaked lime was charged into a stirrer, and a line a that the peripheral speed of the stirring blade of the stirrer and stirred in the above 2m / sec,
Binder X consisting of sintered raw material B group using powder ore of the same particle size or different particle size as the iron ore, and any one or two of quick lime and slaked lime with a 1.0 mm under particle size of 50% by mass or more Line B to which _B is supplied,
After the agitation product obtained in the line A and the supply material in the line B are merged, a pretreatment method of a sintering raw material that is further granulated to obtain a granulated product,
The binder concentration C _A is the percentage of the sintered raw material group A quantity alpha _A and the binder X the quick lime converted amount to the total amount T _A with quicklime equivalent amount beta _A of _A beta _A, the sintered material group B quantities alpha _B and the binder X _B quicklime equivalent amount beta _B and the total amount T the quicklime equivalent amount beta binder concentration C _B in a value obtained by dividing 1 super city is the ratio of _B to _B of, and the binder concentration C _A pretreatment method for a sintering raw material, wherein _B is more than 0.2% by mass. 2. The pretreatment method for a sintered material according to claim 1, wherein a coagulant is blended in at least the line B.

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