JP6036295B2 - Pretreatment method of sintering raw materials - Google Patents

Description

  The present invention relates to a pretreatment method of a sintered raw material for producing a sintered ore which is one of raw materials for steel production.

Sintering raw material is powdered ore (iron ore). Before firing, the powdered ore is mixed with water and subjected to pretreatment such as agitation and granulation, so that the fine powder charged into the sintering machine The amount is reduced. These pretreatments are important operations for maintaining and improving sintering productivity, and various stirring techniques and granulation techniques have been disclosed.
In addition to the progress of pulverization of raw materials due to resource deterioration in recent years, in addition to these various granulation strengthening means, the raw materials are crushed in advance to reduce the fine powder at the stage of supply to sintering. Techniques have been proposed.

For example, in Patent Document 1, high-crystal water ore can be used in large quantities by performing pre-treatment of classifying and crushing pisolite ore with poor water absorption and wettability, stirring and mixing with added water Is disclosed. This is because by performing this pretreatment, moisture permeation into the ore can be promoted, and effective granulated moisture can be secured.
Patent Document 2 discloses that fine powder having a particle size of 45 μm or less contained in the ore can be increased by classifying the blended ore and then pulverizing, thereby improving the granulation property and sinterability. This is because the fine powder described above has good dispersibility and can enhance granulation.

Japanese Patent Laid-Open No. 2003-293043 JP 2008-261016 A

However, when the recently granulated powder ore (that is, a fine powder raw material), which has been increasing in recent years, is blended with the sintered raw material, the raw material was previously crushed (pulverized) as described in Patent Documents 1 and 2 above. Even so, the effect of improving granulation and sintering productivity is limited.
This hardly granulated fine powder raw material has already undergone a pulverization step in the process of beneficiation treatment.
For this reason, even if further crushing is added to the above-mentioned fine powder raw material as in the method described in Patent Document 1, the effect is small, and improvement in water absorption and wettability cannot be expected. In addition, as described above, the method described in Patent Document 2 because most of fine powder having good dispersibility has already been removed from the fine powder raw material by the beneficiation treatment, and the effect of pulverizing the fine powder raw material is small. Even if it employ | adopts, it is difficult to ensure the fine powder of 45 micrometers or less effective for granulation.

  The present invention has been made in view of such circumstances, and improves the granulation property of the sintered raw material, maintains the productivity of the sintered ore, and further improves the use of the fine powder material having difficult granulation property. It is an object of the present invention to provide a pretreatment method of a sintering raw material that enables the above.

Preprocessing method for sintering material according to the present invention along the object, 500 [mu] m under the use of a fine powder material which is more than 50 wt% and 10μm-under 5 wt% grain size of fine ore as iron ore, crystal water In the sintering raw material A group containing 30 to 60% by mass of the high crystal water ore containing 4% by mass or more, a binder consisting of either 1 or 2 of quicklime and slaked lime is converted into the mass of the sintering raw material A in terms of quicklime. Add 0.5 wt% or more and 6 wt% or less, add water so that the moisture content of the sintering raw material group A is 3 to 10 wt%, crush with a crusher, and then stir with a stirrer Then, granulation with a drum granulator, or pulverization with the pulverizer, followed by granulation with the drum granulator . 4 to 1 when the total mass is 100% by mass 2% by mass .

  In the sintering raw material pretreatment method according to the present invention, the temperature of the pulverized product after the pulverization treatment is preferably set to 40 ° C. or more and 80 ° C. or less.

  In the sintering raw material pretreatment method according to the present invention, the moisture content of the sintering raw material group A before the pulverization treatment is preferably 5 mass% or more and 10 mass% or less.

  In the pretreatment method of the sintered raw material according to the present invention, on the condition that the pulverized product after the pulverization treatment is subjected to the stirring treatment with the stirrer, the peripheral speed of the stirring blade of the stirrer during the stirring treatment is It should be 2 m / sec or more.

  In the pre-processing method of the sintering raw material which concerns on this invention, the sintering raw material which uses the pulverized material after the said grinding | pulverization process, and the fine ore of a particle size whose 500 micrometers under is less than 50 mass% or 10 micrometers under is more than 5 mass% as an iron ore. Group B can also be merged.

  The pre-processing method of the sintering raw material which concerns on this invention is 0.5-6 mass% or less in conversion of quick lime to the binder which consists of quick lime and / or slaked lime to the sintering raw material A group which uses a fine powder raw material as iron ore. Addition of the amount and pulverization with a pulverizer facilitates dispersion of fine particles of the binder, and subsequent granulation with a granulator enhances the granulation, thereby improving sintering productivity. .

  Further, when the temperature of the pulverized product after the pulverization treatment is set to 40 to 80 ° C., the temperature of the pulverized product is increased, the digestion reaction is promoted and the precipitation of slaked lime becomes remarkable, and the dispersion of the fine particles of the binder is further promoted. Therefore, it is more preferable.

  And when making the moisture content of the sintering raw material A group before a grinding | pulverization process into 5-10 mass%, promotion of digestion of quick lime, melt | dissolution of slaked lime, and also precipitation of slaked lime are promoted, and dispersion | distribution of the fine particle of a binder is favorable. As a result, the effect of improving the sintering productivity becomes more remarkable.

  Moreover, when the peripheral speed of the stirring blade of the stirrer is 2 m / second or more, an action of mechanically dispersing the binder is added, and as a result, fine powder is reduced, which is more preferable.

  Further, when the pulverized product after the pulverization treatment and the sintered raw material B group having a particle size that is easily granulated as compared with the sintered raw material A group, before merging with the sintered raw material B group, The sintering raw material A group and the binder can be pulverized. As a result, the binder is intensively arranged in the sintering raw material group A having a particle size configuration with poor granulation properties, and the pulverization of the binder is also promoted. Therefore, the sintering raw material group A and the sintering raw material group B are combined. Further, the sintering productivity is further improved as compared with the pulverization process.

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 pulverization conditions have on sintering productivity. It is a graph which shows the influence which the temperature of the ground material after a grinding process and the raw material water | moisture content before a grinding process have on sintering productivity. It is a graph which shows the influence which the addition rate of a quicklime, the grinding | pulverization method, and the peripheral speed of the stirring blade of a stirrer have 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.

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, a large amount of slaked lime that contributes to granulation can be generated by digesting as much quick lime as possible, reducing the particle size of slaked lime generated, dissolving as much slaked lime as possible in granulated water, etc. It is important to disperse the slaked lime to be produced throughout the fine powder raw material (macro dispersion) and to adhere as much as possible to the particle surface of each fine powder raw material (disperse into the micro).
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 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 difficult structure in which 500 μm under which high crystal water ore containing 4% by weight or more of crystal water is blended with 0 or more than 0 and 10% by weight is 50 μm or more and 10 μm under is 5% by weight or less. Add 2% by mass of binder (calcium carbonate, quicklime, slaked lime) to the granular fine powder raw material (sintered raw material A group) (based on 100% by weight of fine powder raw material that is a dry sintered raw material). The mixture was stirred with a universal mixer (a vertical mixer that revolves the axis of a rotating stirring blade) and then 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 (mass% of moisture when the total mass of fine powder raw material and water is 100% by mass, the same applies hereinafter), stirring (kneading): peripheral speed 2.2 m / Second, treatment time 90 seconds, granulation: peripheral speed 1.0 m / second, treatment time 60 seconds. 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: 0.70), 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 sintered raw material A group (a hardly 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% by weight is used. A binder consisting of either 1 or 2 is added in an amount of 0.5 mass% to 6 mass% of the mass of the sintered raw material A group in terms of quick lime, pulverized with a pulverizer, and then stirred with a stirrer. It is a method of granulating with a drum type granulator (drum type granulator) after granulating with a drum type granulator or pulverizing with a pulverizer.
This will be described in detail below.

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.
Table 1 shows the relationship between the particle sizes of the difficult-to-granulate fine powder material and the other easily-granulated material.

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 (sintered raw material B group), which are sintered raw materials obtained by removing the above-mentioned hardly granulated fine powder raw materials from fine ores (iron ores), are “B1” and “B2” in Table 1. ”And“ B3 ”. This easily granulated raw material is a raw material having a particle size of 500 μm under less than 50% by mass or 10 μm under under 5% by mass. Specifically, 500 μm under is less than 50% by mass and 10 μm under is 5%. Raw materials having a particle size of less than or equal to mass% are listed in “B1” in Table 1, and raw materials having a particle size of 500 μm under 50% by mass and 10 μm under 5% by mass are listed in “B2” in Table 1. The raw materials having a particle size in which 500 μm under is less than 50% by mass and 10 μm under is over 5% by 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 stirring 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, 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 mass% and the mass ratio of 10 μm under is 5 mass% is set to “1.0”, respectively. Calculated.
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 influence which the grinding process with respect to a hardly granulated fine powder raw material and quick lime has on sintering productivity is demonstrated, referring FIG.
In various tests, raw granulated raw materials (500 μm under 50 μ% and 10 μm under 5% by mass) of highly granulated ore containing 4% by mass or more high crystal water ore containing 30% by mass of crystal water. 2% by weight is added as an outer shell, water is added so that the moisture content of the hardly granulated fine powder raw material becomes 7% by weight, and the mixture is stirred for 2 minutes with a stirrer. It was set as a basic condition that it was charged in a granulator and rotated 100 times for granulation.

Here, “no pulverization” in FIG. 3 is a result of producing a granulated product under the basic conditions described above without pulverizing both the hardly granulated fine powder raw material and quicklime (as it is).
In addition, “pulverizing only the raw material” in FIG. 3 uses a pulverized product obtained by pulverizing only the hardly granulated fine powder raw material for 5 minutes using a ball mill (pulverizer) and quick lime not subjected to pulverization, It is the result of producing a granulated product under the basic conditions.
And “pulverized only quick lime” in FIG. 3 uses a raw material of hardly granulated fine powder that has not been pulverized, and quick lime that has been pulverized for 5 minutes using a ball mill. It is the result of manufacturing.
Furthermore, the “raw material and quick lime individual pulverization” in FIG. 3 each produced a granulated product under the basic conditions described above, using a hardly granulated fine powder raw material and quick lime that were individually pulverized for 5 minutes using a ball mill. It is a result.
Each temperature of the pulverized product after the pulverization treatment (immediately after pulverization) was normal temperature (25 ° C.).

On the other hand, the “raw material + quick lime mixed pulverization” in FIG. 3 is a result obtained for the purpose of strengthening granulation, and more specifically, 2% by mass of quick lime is added to the hardly granulated fine powder raw material, The mixture obtained by adding water so that the moisture content of the hardly granulated raw material to 3.5% by mass is pulverized using a ball mill for 5 minutes, and then the pulverized product is stirred with an Eirich mixer (stirrer). Processed. In addition, this stirring process was performed for 2 minutes by setting the peripheral speed of a stirring blade to 1 m / sec.
Then, the agitated material described above was charged into a drum mixer, and granulated by rotating 100 times.
The temperature of the pulverized product after the pulverization treatment (immediately after pulverization) was room temperature (25 ° C.).

The granulated product obtained by the various tests described above was charged into a sintering machine and fired, and the sintering productivity was investigated. Note that the productivity index on the vertical axis in FIG. 3 refers to the product (sintering productivity) of the firing rate (kg / hour) and the yield (mass%) for the granulated product obtained in various tests. This is a value calculated by assuming that the sintering productivity obtained by “individual pulverization of raw material and quicklime” is “1” (hereinafter the same).
From Fig. 3, when the pre-pulverization of the difficult-to-granulate fine powder raw material and quick lime is not performed ("no pulverization"), or only the difficult-to-granulate fine powder raw material is pulverized ("crude only raw material"), sintering production The sex was low.
On the other hand, when only quick lime is pulverized ("quick lime only"), the same level of sintered production as when difficult granulated fine powder raw material and quick lime are separately pre-ground ("raw material, quick lime individual pulverization"). Showed sex.

That is, even if only the hardly granulated fine powder raw material is pulverized, the generation of fine particles is small, and it is considered that the effect of improving the sintering productivity is small.
On the other hand, by crushing quicklime, digestion and dispersibility of quicklime are improved. Therefore, it is considered that the sintering productivity is improved as compared with “without crushing”. For this reason, it is considered that the “raw material and quick lime individual pulverization” also has the same sintering productivity as that of “quick lime only pulverization” due to the quick lime pulverization action.
On the other hand, when the hard granulated raw material and quick lime are mixed and pulverized ("raw material + quick lime mixed pulverization"), compared with "raw material and quick lime individual pulverization", the sintering productivity is clearly improved. Was recognized. As factors for this, in addition to the promotion of digestion due to the refinement of quick lime, the action of quick lime dissolution and dispersion by the strong stirring action during pulverization can be considered.

In the above-described test, all of the hardly granulated fine powder raw materials were pulverized together with quick lime, stirred with a stirrer, and granulated with a drum granulator. However, the above easily granulated raw material (quick lime: 2% by mass (the same ratio) added as an outer shell) is added to a stirrer together with the above-mentioned pulverized pulverized product (combined with the pulverized product) B) Agitated and further granulated with a drum granulator, and b) additionally supplied to the drum granulator together with the agitated agitated material after the above pulverizing treatment (stirred material). The same effect as in the above test was obtained even after granulation treatment.
This is due to the fact that the easily granulated raw material to be supplied contains more particles that are over 500 μm compared to the raw material of difficult granulated fine powder, and that the number of particles serving as the core of the pseudo particles increased. Since many particles under 10 μm are contained as compared with the granulated fine powder raw material, it can be considered that adhesion of the fine powder to the core particles during the production of the pseudo particles can be suppressed.

Here, the easily-granulated raw material to be additionally supplied is less than 90% by mass, exceeding 0 or 0 of all the raw materials (total amount of difficult-granulated fine powder raw material and easy-granulated raw material) supplied to the drum granulator. If it is about, the effect of the present invention is remarkably obtained.
Even if the easily granulated raw material is 90% by mass or more (the hardly granulated fine powder raw material is 10% by mass or less), although the effect of the present invention is recognized, Because the ratio is high, the cost of improvement is small.
In the test shown above, the same effect was confirmed even when slaked lime was added instead of or together with quick lime. The quicklime and slaked lime to be added have an effect at a ratio conventionally used (that is, an amount of 0.5% by mass or more and 6% by mass or less of the mass of the sintered raw material A group in a dry state in terms of quicklime). .

Further, here, the case where a ball mill is used as the pulverizer used in the above pulverization process has been described. However, the present invention is not limited to this as long as the pulverization process can be performed. The same effect can be obtained with a machine, hammer crusher, or the like. Note that some pulverizers have a stirring function, such as the above-described ball mill and rod mill. In this case, if necessary, the pulverization process and the stirring process are performed with a pulverizer having a stirring function. The treated product can be granulated with a granulator without separately stirring with a stirrer (via a stirrer).
Here, the time for the pulverization treatment can be appropriately set based on the effect obtained by the pulverization treatment (for example, the improvement effect of the productivity index as shown in FIG. 3). It is good to process for 30 seconds or more with a rod mill and a hammer crusher, and 1 pass or more with a roller-type pulverizer.

Next, the temperature of the pulverized product at the time of mixing and pulverizing the hardly granulated fine powder raw material and quick lime (immediately after the pulverization process) and the water content (raw material moisture) of the difficult granulated fine powder raw material before the pulverization process are sintered production. The influence on the property will be described with reference to FIG.
In the test, as in FIG. 3 described above, a hardly granulated raw material containing 30 to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water (500 μm under is 50% by mass and 10 μm under is 5% by mass). %), Quick lime was added in an amount of 2% by mass, and the raw material was added so that the water content of the hardly granulated fine powder material was 3 to 10% by mass, and this was pulverized using a ball mill. Then, this pulverized product was stirred for 2 minutes with an Eirich mixer (circumferential speed of stirring blade: 1 m / second), and then this stirred product was charged into a drum mixer and granulated by rotating 100 times. The temperature of the pulverized product is adjusted by changing the pulverization time with the ball mill and the rotation speed of the ball mill (there is also the heat generation of quick lime). Adjustment was made by changing the moisture content of the granulated fine powder material (mass% of moisture when the total mass of the hardly granulated fine powder material and water was 100% by mass).

Note that the productivity index on the vertical axis in FIG. 4 refers to the product (sintering productivity) of the firing rate (kg / hour) and the yield (mass%) for the granulated product obtained under each condition. It is a value calculated by assuming that the sintering productivity obtained by “individual pulverization of raw material and quicklime” shown in FIG. 3 is “1”.
From FIG. 4, the temperature after the pulverization treatment of the hardly granulated fine powder raw material is 25 ° C. to 40 ° C., 50 ° C., which is normal temperature, regardless of the change in the moisture content of the hardly granulated fine powder raw material before the pulverization treatment. As the temperature rose to 80 ° C., improvement in sintering productivity was confirmed. In particular, the effect when the temperature was raised from room temperature to 40 ° C. was remarkable.
As this factor, it is conceivable that quick lime (slaked lime) digested and dissolved is finely precipitated and dispersed due to a temperature rise during pulverization (during pulverization).
In addition, when the temperature after the pulverization treatment was 80 ° C., the evaporation of moisture became remarkable, and the sintering productivity decreased.

In addition, regardless of the change in temperature after the pulverization treatment of the hardly granulated fine powder raw material, 5 mass% (when the moisture content of the hardly granulated fine powder raw material before the pulverization treatment is 3 mass% (Δ mark) ( Sintering productivity was improved by increasing it to 10% by mass (◯). In particular, when the moisture content of the difficult-to-granulate fine powder raw material was increased from 3% by mass to 5% by mass, the rate of increase in the effect increased. lost.
As this factor, it is considered that the dispersibility is improved due to the increase in moisture resulting in an increase in dissolution of quicklime and precipitation media.
In addition, although it depends on the weather, it is a rare phenomenon that the moisture content of a hardly granulated fine powder raw material falls to 3 mass%.

From the above, it is preferable to set the temperature of the pulverized product after the pulverization to 40 ° C. or higher and 80 ° C. or lower (further, the lower limit is 45 ° C. and the upper limit is 75 ° C.).
Moreover, it is preferable that the moisture content of the sintering raw material A group before pulverization is 5% by mass or more and 10% by mass or less (further, the lower limit is 6% by mass and the upper limit is 9% by mass). Note that the amount of water added in the stirring treatment or granulation treatment may be an amount capable of obtaining the effect of digesting quick lime (slaked calcification) or dissolving slaked lime, and the amount of moisture conventionally used in stirring or granulation (for example, stirring) The effect is obtained at 4 to 12% by mass when the total mass of the sintering raw material and water to be treated or granulated is 100% by mass).
In the test shown above, the same effect was confirmed even when slaked lime was added instead of or together with quicklime. The quicklime and slaked lime to be added have an effect at a ratio conventionally used (that is, an amount of 0.5% by mass or more and 6% by mass or less of the mass of the sintered raw material A group in a dry state in terms of quicklime). .

Then, the influence which the addition ratio of a quicklime, the grinding | pulverization method, and the peripheral speed (stirring speed) of the stirring blade of a stirrer have on sintering productivity is demonstrated, referring FIG.
The raw material used in the test was the same as in FIG. 3 described above, a hardly granulated raw material containing 30 to 60% by mass of high crystal water ore containing 4% by mass or more of crystal water (500 μm under is 50% by mass and 10 μm) Under is 5% by mass or less).
Quick lime was added to this raw material as an outer shell by 0.5% by mass, 1.0% by mass, 2.0% by mass and 6.0% by mass, respectively, and pulverized for 5 minutes using a ball mill. In addition, since the raw material water | moisture content before a grinding | pulverization process was 3 mass%, it was added to 6 mass%, and the temperature of the pulverized material after a grinding | pulverization process was 40 degreeC.

The pulverized product was mixed and stirred with a high-speed stirring mixer. In addition, the circumferential speed (stirring speed) of the stirring blade at the time of stirring was adjusted to 1 m / sec (Δ mark), 2 m / sec (□ mark), and 3 m / sec (◯ mark), respectively, and stirred. Moreover, the water content at the time of stirring was adjusted so that it might become 7 mass% with respect to the total amount of the raw material and water | moisture content which are stirred.
This stirred product was further put into a drum mixer and granulated for 4 minutes.
On the other hand, as a comparative example (x mark), the above-mentioned finely granulated fine powder raw material and quick lime having the above-mentioned particle size constitution were individually pulverized, and the pulverized quick lime was described above for the pulverized hardly granulated fine powder raw material. After adding the amount of four conditions, this was mixed and stirred with a high-speed stirring mixer (peripheral speed: 1 m / second), and then a granulated product granulated for 4 minutes with a drum mixer was used.
The evaluation is performed by filling the granulated material obtained by the above-described method into a sintering machine and firing it, and then calculating the product of sintering rate (kg / hour) and yield (mass%) as the sintering productivity (kg / Time) was evaluated, and the sintering productivity of the comparative example described above was set to “1.0”, and the sintering productivity of each condition was comparatively evaluated.

From FIG. 5, regardless of the change in the stirring speed, when the difficult-to-granulate fine powder raw material and quicklime are mixed and pulverized (△ mark, □ mark, ○ mark), the base conditions are individually pulverized (× mark) ), It was confirmed that the sintering productivity was improved when the addition ratio of quicklime was in the range of 0.5 mass% to 6 mass% (sintering productivity exceeded 1 under all conditions).
Furthermore, with respect to the influence of the stirring speed, the improvement effect is greater when the peripheral speed of the stirring blade is 2 m / second (marked with □) compared to 1 m / second (marked with △), and further 3 m / second (marked with ○). Then, the tendency that the improvement effect is saturated was confirmed.
From the above results, it was defined that the binder added to the sintering raw material A group was added in an amount of 0.5 mass% or more and 6 mass% or less of the mass of the sintering raw material A group in terms of quick lime.

Further, when the pulverized product after the pulverization treatment is stirred using a stirrer, the peripheral speed of the stirring blades of the stirrer is preferably 2 m / second (more preferably 3 m / second) or more.
The stirrer is not particularly limited as long as the peripheral speed of the stirring blade can be 2 m / second or more. For example, the above-described universal mixer can be used. Here, the upper limit value of the peripheral speed of the stirring blade is not particularly limited from the above description, but is, for example, about 35 m / second in consideration of a stirring machine 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.

Next, the mixing time of the hardly granulated fine powder material and the easily granulated material will be described.
In the test, 70% by mass of a difficult-to-granulate fine powder material in which 500 μm under is 50% by mass or more and 10 μm under is 5% by mass and easy granulation in which 500 μm under is less than 50% by mass or 10 μm under is more than 5% by mass. 30% by mass of the raw material was used.
Here, as test condition 1, all of the difficult-to-granulate fine powder raw material, the easily granulated raw material, and quicklime are pulverized with a ball mill, then stirred with a high-speed stirring mixer, and further granulated with a drum mixer. did. As test condition 2, quick lime is added to the hardly granulated fine powder raw material, pulverized with a ball mill, then easily granulated raw material is added to the pulverized product, and the mixture is stirred with a high-speed stirring mixer, and further with a drum mixer. Granulated.

In addition, the addition amount of quicklime was 2.0 mass% with the outer shell with respect to the total amount of a hardly granulated fine powder raw material and an easily granulated raw material.
Moreover, the grinding time with the ball mill was set to 5 minutes. At this time, the water content of the raw material before the pulverization treatment was added from 3% by mass to 6% by mass, and the raw material temperature after the pulverization treatment was set to 40 ° C.
And the stirring process with a high-speed stirring mixer set the peripheral speed of the stirring blade at the time of stirring to 2 m / sec. At this time, the water content of the stirred product was adjusted to 7% by mass with respect to the total amount of the raw material to be stirred and the water content.
Furthermore, the granulation process by the drum mixer was performed for 4 minutes.
The evaluation is performed by filling the granulated product obtained by the above-described method into a sintering machine and firing it, and then obtaining the sintering productivity (kg / hour) by the product of the firing rate (kg / hour) and the yield (mass%). ) Was performed.

When quick lime is added only to the difficult-to-granulate fine powder raw material, and the easy-granulated raw material is added after the pulverization treatment, the whole amount of the hard-to-granulate fine powder raw material, quick lime and the easily granulated raw material is crushed As a result, the sintering productivity was improved by about 5%. This is because by adding quick lime only to the difficult-to-granulate fine powder raw material and crushing it, the granulation strengthening effect and the grinding load due to the quick lime being selectively placed around the hard-to-granulate fine powder raw material are reduced. This is considered to be an effect of improving the grindability of quicklime.
Therefore, it is preferable to mix the pulverized raw material, quick lime and slaked lime and pulverize them, and then add the easily granulated raw material to this and stir, and further granulate. The raw material, quick lime and slaked lime are mixed, pulverized and stirred, and then an easily granulated raw material is added thereto for granulation.

A sintered ore can be manufactured by charging the granulated material obtained by the above-described method into a pallet of a sintering machine.
From the above, by using the sintering raw material pretreatment method of the present invention, it is possible to improve the granulation property of the sintering raw material and maintain and further improve the productivity of the sintered ore while It was confirmed that a fine powder material having graininess can be used.

  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 (5)

As the iron ore, a fine powder raw material having a particle size of 500 μm under 50% by mass and 10 μm under 5% by mass is mixed with 30-60% by mass of high crystal water ore containing 4% by mass or more of crystal water. the sintering material group a, a binder composed of any one or two of quicklime and slaked lime, the sintering raw material a was added in an amount of less than 0.5 wt% or more 6 wt% by weight of group with quicklime terms, wherein the sintering Water is added so that the water content of the binding raw material group A becomes 3 to 10% by mass, and after pulverizing with a pulverizer, stirring with a stirrer and granulating with a drum granulator, or with the pulverizer After the pulverization treatment, granulation is performed with the drum type granulator , and the water content in the granulation treatment is 4 to 12% by mass when the total mass of the sintering raw material and water is 100% by mass . Pretreatment method for sintered raw material . 2. The pretreatment method for a sintered material according to claim 1, wherein the temperature of the pulverized product after the pulverization is set to 40 ° C. or more and 80 ° C. or less. The pretreatment method of the sintering raw material according to claim 1 or 2, wherein the moisture content of the sintering raw material group A before the pulverization treatment is 5 mass% or more and 10 mass% or less. Pre-processing method. In the pre-processing method of the sintering raw material according to any one of claims 1 to 3, the pulverized material after the pulverization treatment is subjected to the stirring treatment with the stirrer, and the stirring treatment is performed. A pretreatment method for a sintering material, wherein the peripheral speed of the stirring blade of the stirrer is 2 m / second or more. In the pre-processing method of the sintering raw material of any one of Claims 1-4, 500 micrometer under is less than 50 mass% or 10 micrometer under is more than 5 mass% as a pulverized material after the said grinding | pulverization process, and an iron ore. A pretreatment method for a sintering material, characterized in that the sintering material B group using granular ore of particle size is merged.

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