JP2015203132A - Pretreatment method of sinter raw material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pretreatment method of a sinter raw material capable of suppressing insufficiency of burning while sintering which is generated when a sinter raw material including many fine powders is granulated with high moisture content, and improving productivity of a sinter machine.SOLUTION: The pretreatment method of a sinter raw material is configured to; granulate a sinter raw material A including fine powders whose diameter is less than 500 μm by equal to or more than 15 mass% with 10 mass%-13 mass% of moisture content for forming a granulation object AA; mix a sinter raw material B with 0 mass%-9 mass% of moisture content to the granulation object AA for forming a granulation object AAB; and add the granulation object AAB to a granulation object CC formed by granulating a sinter raw material C including an iron ore and a coagulation material.

Description

  The present invention relates to a granulation treatment that is performed in advance on a sintering raw material charged in a sintering machine in order to improve the productivity of the sintering machine.

The productivity of a sintering machine for producing sintered ore is expressed as firing rate × yield after firing. Therefore, in order to improve the productivity of the sintering machine, it is necessary to improve the firing rate and / or the yield after firing.
The firing speed is determined in consideration of the red tropical descending speed in the sintering machine pallet, the pallet area, the bulk density of the sintered raw material, and the like. In order to increase the red tropical fall rate and improve the firing rate, it is important to improve the air permeability of the raw material layer. Therefore, air permeability is improved by granulating a sintering raw material beforehand and reducing fine powder.

  However, with the recent deterioration of resources, for example, a sintering raw material containing 15% by mass or more of fine powder (fine ore) under 500 μm is increasing. The importance of reducing granulated fines) is increasing.

  Therefore, Patent Document 1 describes granulating a sintered raw material with high moisture for the purpose of strengthening the granulation of the sintered raw material. More specifically, a method of granulating a sintered raw material mainly composed of fine powder with a first granulator and then supplying the granulated material together with another sintered raw material to a second granulator. Is described. In this method, the water added in the first granulator is equivalent to the water content absorbed by the sintering raw material mainly composed of fine powder, and further 2.5% by mass to 4.0% by mass of the water content equivalent. It is characterized by the amount of the following water added.

  Moreover, in patent document 2, like the invention of patent document 1, the granulation system is divided into two systems, and one of the divided raw materials is granulated with a water content of 8.0 to 11.1% by mass to produce one pseudo particle. And the other raw material is granulated at a moisture content of 6.0 to 7.5% by mass to form the other pseudo particle, and both pseudo particles are supplied to the sintering machine without mixing with a drum mixer. (For example, claim 1).

JP 2008-101263 A JP 2009-209408 A

  However, in the case of the method described in Patent Document 1, granulation is performed by adding 2.5% by mass or more and 4.0% by mass or less of water to the water content of the sintering raw material. Although the granulation property is good, the adhesion of the granulated product itself is also increased. Therefore, in the process of granulating the granulated material together with other sintered raw materials in a second granulator such as a drum mixer, the coagulant blended with the other sintered raw materials is the first. It adheres to the granulated material granulated by this granulator and forms a coagulant layer on its surface. As a result, a part of the buried condensed material does not generate oxidation heat, resulting in insufficient firing.

  On the other hand, in the method described in Patent Document 2, in order to supply one pseudo particle and the other pseudo particle to a sintering machine without mixing with a drum mixer, for example, a coagulant mixed in the other sintering raw material Is not taken into one of the pseudo particles. Therefore, it is possible to suppress the occurrence of insufficient firing due to the buried of the aggregating material. However, since one pseudo particle has a lot of moisture, the pseudo particles tend to stick together and become agglomerated, and the one pseudo particle and the other pseudo particle are not mixed with a drum mixer or the like, for example, a sintering machine. When being stacked on the belt conveyor in the process of transport to and fed to the sintering machine, a portion where one pseudo particle is unevenly distributed in the sintering raw material supplied to the sintering machine, that is, a portion where moisture is unevenly distributed occurs, This causes insufficient firing during sintering.

  Note that claim 3 of Patent Document 2 describes that the moisture difference between one pseudo particle and the other pseudo particle is limited (3.1% by mass or less) as a configuration for suppressing insufficient firing. This method makes it possible to suppress insufficient baking due to the uneven distribution of moisture, but it is a moisture control that is not based on granulation properties, which causes a lack of moisture and excessive moisture during granulation. In the case of insufficient moisture, the ungranulated fine powder reduces the air permeability during sintering, leading to a decrease in the firing rate and insufficient firing. On the other hand, excessive moisture causes an increase in the moisture of the entire sintering raw material supplied to the sintering machine (the amount of water brought into the sintering machine), which leads to insufficient firing under a constant firing rate.

  The present invention has been made in view of such circumstances, and improves the productivity of the sintering machine by suppressing the shortage of firing during sintering that occurs when a sintering raw material with a lot of fine powder is granulated with high moisture. It is an object of the present invention to provide a pretreatment method for a sintering raw material that can be used.

In order to achieve the above object, the first invention is a granulated product AA by granulating a sintering raw material A containing 15% by mass or more of fine powder of 500 μm or less with a water content of 10% by mass to 13% by mass,
The granulated product AA is mixed with a sintering raw material B having a moisture content of 0% by mass to 9% by mass to obtain a granulated product AAB.
The granulated product AAB is added to a granulated product CC obtained by granulating a sintered raw material C containing iron ore and a coagulant.

The coagulant mainly contains carbon, and is a material that generates heat by oxidation. For example, it refers to coal and coke.
Moreover, the said water | moisture content (mass%) is a value calculated by following Formula.
Moisture = Amount of added water / (Amount of sintering raw material + Amount of added water) × 100

Sintered raw material A containing 15% by mass or more of fine powder (powder ore) of 500 μm or less is a difficult-granulating raw material with a lot of fine powder and difficult to granulate. 13% by mass) to obtain a granulated product AA. However, since the granulated product AA contains a lot of moisture, the granulated products AA adhere to each other remarkably, and when mixing by a drum mixer or the like is not performed, the granulated product AA does not disperse and is poorly fired due to uneven distribution of moisture ( Causes burning unevenness.
Therefore, in the present invention, the low-moisture sintered raw material B is produced by mixing the granulated material AA that causes the condensing material to be buried and the low-moisture (water 0 mass% to 9 mass%) sintered raw material B. A granulated product AAB applied to the surface of the granular product AA is manufactured. The granulated product AAB has a layer made of a low-moisture sintered raw material B on its surface, so its adhesion is smaller than that of the granulated product AA, and the dispersibility of the granulated product AAB in the subsequent process is guaranteed. Is done. As a result, uneven distribution of the granulated product AAB is suppressed, and insufficient firing due to uneven burning can be suppressed.

  In addition, in the first invention, the granulated product AAB is added to the granulated product CC obtained by granulating the sintered raw material C containing the iron ore and the coagulating material, that is, the sintered raw material C containing the coagulating material. Since the granulated product AAB is added after the granulation, the sintering raw material C is less likely to adhere to the granulated product AAB, and it is possible to suppress a shortage of firing due to the buried of the coagulant in the granulated product AAB.

Moreover, 2nd invention granulates the sintering raw material A containing the fine powder of 500 micrometer under 15 mass% or more with the water | moisture content of 10 mass%-13 mass%, and is set as granulated material AA,
The granulated product AA is mixed with a sintering raw material B having a moisture content of 0% by mass to 9% by mass to obtain a granulated product AAB.
The sintered raw material C containing iron ore and a coagulant is charged into a granulator and granulated for 120 seconds or more to obtain a granulated product CC having a water content of 5% by mass to 9% by mass. It is characterized in that the granulated product AAB is added.

  In the second invention, by adding the granulated product AAB to the granulated product CC being granulated, uneven distribution of the granulated product AAB can be suppressed and uneven burning can be suppressed. At that time, the present inventors found that when the granulated material AAB was added after charging the sintered raw material C into the granulator and granulating for 120 seconds or more, there was no shortage of firing. This is considered to be because granulation of the granulated product CC is almost completed in about 120 seconds, and no condensate is buried in the granulated product AAB.

  Moreover, in the pre-processing method of the sintering raw material which concerns on this invention, it is suitable that the moisture difference of the said granulated material AAB and the said granulated material CC shall be 3 mass% or less. Thereby, uneven distribution of moisture can be suppressed and burn unevenness can be suppressed.

  In the pretreatment method of the sintered raw material according to the present invention, the granulated product AAB in which the low-moisture sintered raw material B is applied to the surface of the granulated product AA containing a large amount of fine powder and containing a large amount of water is manufactured. Since the granulated product AAB is added to the granulated product CC obtained by granulating the sintered raw material C containing the coagulating material, it is caused by the embedding of the coagulating material and the uneven distribution of water that occur when the sintered raw material with a lot of fine powder is granulated with high moisture. Insufficient firing is suppressed, and the productivity of the sintering machine can be improved.

It is a schematic diagram which shows the outline of the pre-processing method of the sintering raw material which concerns on the 1st Embodiment of this invention. It is a schematic diagram which shows the outline of the pre-processing method of the sintering raw material which concerns on the 2nd Embodiment of this invention. (A) is a schematic diagram of a batch type drum mixer, (B) is a schematic diagram of a continuous drum mixer. It is the graph which showed the relationship between the moisture content of granulated material AA, and the amount of residual fine powder in granulated material AA. The relationship between the moisture content of the granulated product AAB and the yield after baking in the pot is shown. (A) is a graph when the moisture content of the granulated product AA is 10% by mass and the moisture content of the granulated product CC is 7% by mass, (B ) Is a graph when the moisture of the granulated product AA is 13% by mass and the moisture of the granulated product CC is 7% by mass. The relationship between the granulation time of the sintered raw material C at the time of addition of the granulated product AAB and the yield after the pot firing is shown, (A) is a graph when the moisture content of the granulated product AA is 10% by mass, and (B) is It is a graph in case the moisture of granulated material AA is 13 mass%. The graph which showed the influence which the water | moisture content difference of granulated material AAB and granulated material CC has on the yield after a pot baking when the moisture of granulated material AA is 10 mass% and the moisture of granulated material CC is 5 mass%. It is. The graph which showed the influence which the water | moisture content difference of granulated material AAB and granulated material CC has on the yield after a pan baking when the moisture of granulated material AA is 13 mass% and the moisture of granulated material CC is 7 mass% It is. The graph which showed the influence which the water | moisture-content difference of granulated material AAB and granulated material CC has on the yield after a pan baking when the moisture of granulated material AA is 13 mass% and the moisture of granulated material CC is 9 mass%. It is.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.

[Sintering Raw Material Pretreatment Method According to First Embodiment]
A pretreatment method for a sintering material according to the first embodiment of the present invention will be described with reference to the schematic diagram of FIG.
(1) Water (moisture of 10% by mass to 13% by mass) is added to the sintering raw material A containing 15% by mass or more of fine powder (powder ore) of 500 μm or less, and the granulated product AA by a granulator a10 such as a stirrer. Granulate. Since the granulated product AA contains a lot of moisture, it has strong adhesion and is easily agglomerated as shown in FIG.

(2) Sintering raw material B having a moisture content of 0% by mass to 9% by mass is added to the granulated product AA, and the granulated product AAB is granulated by a mixer 12 such as a pan pelletizer. The agglomerated granulated product AA is dispersed in the mixer 12, and the sintered raw material B with less water adheres to the surface of the granulated product AA. Since the granulated product AAB has less water than the granulated product AA, the agglomeration hardly occurs (see FIG. 1).

(3) A sintered raw material C containing iron ore and a coagulant is charged into a granulator c11 and granulated to produce a granulated product CC (see FIG. 1). A drum mixer etc. can be used for the granulator c11.
(4) The granulated product AAB is added to the granulated product CC discharged from the granulating device c11 and conveyed by a belt conveyor (not shown). The granulated product CC and the granulated product AAB are mixed at the connecting portion of the belt conveyor, and the granulated product CC and the granulated product AAB are mixed (see FIG. 1).
In addition, it is preferable that the water | moisture-content difference of granulated material AAB and granulated material CC shall be 3 mass% or less.

[Sintering Raw Material Pretreatment Method According to Second Embodiment]
A pretreatment method for a sintering raw material according to the second embodiment of the present invention will be described with reference to the schematic diagram of FIG.
(1) A granulated product AAB is manufactured by the same procedure as in the first embodiment (see FIG. 2).
(2) A sintered raw material C containing iron ore and a coagulant is charged into a granulator c11 and granulated for 120 seconds or more to obtain a granulated product CC having a moisture content of 5 to 9% by mass. The granule AAB is charged into the granulator c11 from the outlet side of the granulator c11 (see FIG. 2).
As in the first embodiment, the moisture difference between the granulated product AAB and the granulated product CC is preferably 3% by mass or less.

At that time, when the granulating apparatus c11 is a batch type drum mixer as shown in FIG. 3A, it is easy to control the granulating time of the sintering raw material C, but as shown in FIG. 3B. In the case of a continuous drum mixer, the granulation time is controlled using equation (1).
Granulation time (min) = K x axial length (m) ÷ (drum mixer tilt angle (°)
× Drum rotation speed (rpm) × Drum inner diameter (m)) (1)
However, K is a coefficient and takes a different value depending on the raw material. In this embodiment, K = 10.47. The drum mixer tilt angle is 1 ° to 15 °, the drum rotation speed is 1 rpm to 100 rpm, and the drum inner diameter is 1 m to 10 m.

[Relationship between granulation strengthening and added moisture of sintering raw material A containing fine powder]
In order to clarify the relationship between the granulation strengthening of the sintering raw material A containing fine powder and the added moisture, the residual fine powder (0.5 mm) contained in the granulated product AA granulated using the moisture added to the sintering raw material A as a parameter. The amount of under) was investigated (first test).

A high-speed stirrer (Eirich mixer) is added to 2% by mass of quicklime as a binder and water (water content 9% to 13% by mass) as a binder to sintering raw material A containing 55% by mass of fine powder of 0.5 mm (500 μm) under. ) To granulate the granulated product AA.
Fine powder containing Yandy ore was used for the sintering raw material A, and the granulated product AA was obtained by stirring for 40 seconds with the rotation speed of the high-speed stirrer being 415 rpm.

  And it investigated about the quantity of the residual fine powder (0.5 mm under) contained in the obtained granulated material AA. The amount of residual fine powder contained in the granulated product AA is measured by drying the granulated product AA after the granulation treatment to a moisture content of 0% by mass, and a low-tap shaker for 15 seconds against 0.5 mm sieve of JISZ8801-1. After carrying out mechanical sieving according to the above, the mass under the sieve was measured, and (the mass under the sieve) / (the mass on the sieve + the mass under the sieve) × 100 (mass%) was defined as the amount of residual fine powder.

The test results are shown in FIG. The figure shows the following.
In the case of a sintered raw material having a large amount of fine powder, granulation with 10% by mass or more of moisture reduces ungranulated fine powder (residual fine powder). However, when the water content exceeds 13% by mass, there is a tendency that the adhesion of the sintered raw material to the high-speed stirrer and the like tends to increase, so the upper limit value of the water content is set to 13% by mass.
In addition, when the 0.5 mm under fine powder was tested at 15% by mass to 100% by mass, the numerical value on the vertical axis was different, but when the water content was 10% by mass or more, the ungranulated fine powder decreased. Moreover, the same tendency was seen also when the ratio of the quicklime as a binder was changed by 0 mass%-6 mass%.

[About the effect of spraying the sintering raw material B on the surface of the granulated product AA]
In order to clarify the effect of spraying the sintered raw material B on the surface of the granulated product AA, the yield after the pan firing was investigated using the moisture of the granulated product AAB as a parameter (second test).

  Sintered raw material A containing 40% by mass of fine powder under 0.5 mm is granulated, and granulated product AA containing 3% by mass to 5% by mass of fine powder under 0.5 mm (water content: 10% by mass to 13% by mass) Granulated. The kind and granulation conditions of the sintering raw material A are the same as in the first test.

Then, the sintered raw material B containing 70% by mass of 0.5 mm under fine powder, 8% by mass and 9% by mass of moisture is added to the granulated product AA and mixed by a pan pelletizer, and 9% by mass to 12.7% of moisture is obtained. A mass% granulated product AAB was produced. The water content of the granulated product AAB was adjusted by the blending ratio of the granulated product AA and the sintering raw material B.
For the sintering material B, kneaded dust was used. Moreover, the rotation speed of the pan pelletizer was 29 rpm, and the mixing time (1 to 3 minutes) was adjusted so that the 0.5 mm under fine powder contained in the granulated product AAB would be 5 to 10% by mass.

Further, a sintering raw material C containing 10% by mass of fine powder of 0.5 mm under, 5% by mass of a coagulant, and 4% by mass of moisture is charged into a granulating apparatus c, and granulated. A granulated product CC containing 0% by mass to 2% by mass of 5 mm under fine powder and having a moisture content of 7% by mass was produced.
As the sintering raw material C, lobe ore, return ore, and the like were used. In addition, a drum mixer was used as the granulator c, and the drum mixer was rotated at 25 rpm and the granulation time was 2 minutes.

Next, the mass ratio of the granulated product CC and the granulated product AAB is set to 70%: 30%, and the granulated product CC and the granulated product AAB are loaded on the belt conveyor, and the granulated product CC is transferred by six belt conveyor connections. And the granulated product AAB were mixed, and the yield after baking the pot was investigated using a sintering pot testing apparatus (not shown).
As a result of mixing the granulated product AAB at the connecting portion of the granulated product CC and the belt conveyor, it was visually confirmed that the granulated product AAB was well dispersed.

  The fired product fired by the sintering pot test apparatus was dropped four times from a height of 2 m, and the ratio at which 6 mm over remained was defined as the yield after pot firing. Further, since the sintering pot test is affected by fine powder, as described above, 0.5 to 10% by weight of 0.5 mm under fine powder contained in the granulated product AAB is contained in the granulated product CC. The reliability of the sintering pot test was ensured by adjusting the fine powder under 5 mm to 0 to 2% by mass.

  The test results are shown in FIGS. 5 (A) and 5 (B). In the figure, ▪ indicates the result when the moisture of the sintering material B is 9% by mass, and ▲ indicates the result when the moisture of the sintering material B is 8% by mass. 5 (A) shows the result of mixing with the granulated product CC by the above-described method without adding the sintering raw material B to the granulated product AA having a moisture content of 10% by mass. ) Indicates the results of mixing with the granulated product CC by the above method without adding the sintering raw material B to the granulated product AA having a moisture content of 13% by mass.

The figure shows the following.
-The yield after sintering the pot is improved by coating the surface of the granulated product AA with the low moisture sintering raw material B. As a factor of improving the yield after pot sintering by covering the sintered raw material B, the low-moisture sintered raw material B is applied to the surface of the granulated product AA to obtain the granulated product AAB. As a result of the formation of a low-moisture layer on the surface of the steel sheet and the decrease in adhesion, it is considered that the mixing at the time of connecting the belt conveyor was improved and the uneven burning was suppressed.
-The moisture of the sintering raw material B which forms a low moisture layer needs to be less than 10 mass%, and is 9 mass% or less which is a safe value.
-The yield after pot baking improves, so that the water | moisture content of granulated material AAB falls. This is because the effect of the present invention is not influenced by the blending ratio of the granulated product AA and the sintered raw material B. If the surface of the granulated product AA is covered with the sintered raw material B even a little, This shows that the yield is improved. In addition, the said tendency was recognized to the water | moisture content of the granulated material AAB to 6.6 mass%.

As described above, the moisture of the granulated product AAB is reduced by coating the surface of the granulated product AA with the low moisture sintering raw material B. Then, by adding the granulated product AAB to the granulated product CC after granulation, the dispersibility of the granulated product AAB is realized while realizing good granulation property of the sintered raw material A and suppression of flocculation material burying. It is possible to suppress burning unevenness by securing. In addition, it becomes possible to produce a granulated product that can suppress firing shortage, and the yield after firing the sintered raw material is improved.
In addition, it is confirmed that it is the same tendency when the water | moisture content of the granulated material CC is changed between 5 mass%-9 mass%.

  In this test, the granulated product AAB was 30% by mass of the total blended raw material in a dry state, but the effect is not limited to the above-mentioned blending ratio, for example, even when it is 10% by mass to 60% by mass. It becomes the tendency. This tendency is the same in the subsequent tests.

[Effect of adding granulated product AAB during granulation of granulated product CC]
In order to clarify the effect of adding the granulated product AAB during the granulation of the granulated product CC, the yield after baking was investigated using the granulation time of the sintered raw material C at the time of adding the granulated product AAB as a parameter ( Third test).

The kind of the sintering raw material A and the granulation conditions of the granulated product AA are the same as in the second test.
A sintering raw material B containing 70% by mass of 0.5 mm under fine powder and having a moisture content of 9% by mass is added to the granulated product AA and mixed by a pan pelletizer, and a moisture content of 9.6% to 11.7% by mass is produced. Granule AAB was produced. In addition, the ratio of the granulated material AA and the sintering raw material B was constant at 2: 1.
The kind of the sintering raw material B, the rotation speed of the pan pelletizer, the mixing time, and the like are the same as in the second test.

Moreover, after putting the sintering raw material C used for the 2nd test into the granulation apparatus c and granulating it so that a water | moisture content may be 7 mass%, it is set as the granulated material CC, Then, in the granulation apparatus c The granulated product AAB was added. The timing of adding the granulated product AAB was 80 seconds to 180 seconds after the start of granulation of the sintered raw material C, and the time from the start of granulation of the sintered raw material C to the end of granulation was 3 minutes. The granulated product CC after the completion of granulation contained 3% to 5% by mass of 0.5 mm under fine powder, and the moisture content was 7.8% to 8.4% by mass.
In addition, a drum mixer is used for the granulator c, and the rotation speed of the drum mixer is 25 rpm.

  The test results are shown in FIGS. 6 (A) and 6 (B). 6 (A) shows the result of mixing with the granulated product CC by the above-described method without adding the sintering raw material B to the granulated product AA having a moisture content of 10% by mass. “◇” indicates the result of mixing with the granulated product CC by the above-described method without adding the sintering raw material B to the granulated product AA having a moisture content of 13% by mass. Moreover, the data shown with the broken line has shown the result of having added granulated material AAB on the belt conveyor.

The figure shows the following.
-The timing which adds granulated material AAB to the granulator which granulates the sintering raw material C is after granulating the sintering raw material C for 120 seconds or more. When the granulated product AAB is added at a timing when the granulation time is shorter than that, granulation of the granulated product CC is not completed, and the condensed material is buried in the granulated product AAB, resulting in insufficient firing. Conceivable.
-Pre-treatment of the sintering raw material according to the first embodiment when the granulated material AAB is added to the granulating device after charging the sintering raw material C into the granulating device and granulating for 120 seconds or more. Compared with the method (data indicated by the broken line), the yield after firing is improved. This is considered to be because the mixing state of the granulated product AAB and the granulated product CC was further improved, and the uneven burning due to the uneven distribution of the granulated product AAB was suppressed.
-It confirmed that it became the same tendency when the granulation water | moisture content of the sintering raw material C was 5 mass%-9 mass%. However, when the granulated moisture of the sintering raw material C was less than 5% by mass, remarkable firing shortage occurred. This is thought to be because the agglomerated material in the sintered raw material C was buried in the granulated product AAB because the granulation of the sintered raw materials C was extremely deteriorated.
-The tendency for the yield after pot baking to improve so that the moisture of granulated material AAB falls is the same as that of the pre-processing method of the sintering raw material which concerns on 1st Embodiment, and concerns on 2nd Embodiment. Even in the pretreatment method of the sintered raw material, the effect is not influenced by the blending ratio of the granulated product AA and the sintered raw material B. Yield after baking is improved. Further, it has been confirmed that the same tendency can be obtained up to 6.6% by mass of the water of the granulated product AAB.

  As described above, the addition of the granulated product AAB to the granulated product CC during granulation, and the granulated product AAB after granulating the sintered raw material C for 120 seconds or more, suppresses the flocculation material from being buried. , The mixed state of the granulated product AAB and the granulated product CC is improved, and the uneven distribution of the granulated product AAB is suppressed. As a result, burn unevenness is remarkably suppressed, and it becomes possible to produce a granulated product that can suppress firing shortage with a granulator, and the yield after sintering of the sintered raw material is improved.

[Relationship between moisture of granulated product AAB and moisture of granulated product CC]
In order to clarify the relationship between the moisture content of the granulated product AAB and the moisture content of the granulated product CC, the yield after baking was investigated using the difference in moisture between the granulated product AAB and the granulated product CC as a parameter (No. 4 Test).

  The types of sintering raw materials A, B, and C, granulation conditions, and the like are substantially the same as in the third test. However, the moisture of the sintering raw material B is 0% by mass to 9% by mass, and the moisture of the granulated product AAB is 6.6% by mass to 11.7% by mass. Moreover, after charging the sintering raw material C into the granulator c and granulating it so that the water content is 5 mass% to 9 mass% to obtain a granulated product CC, the granulation of the sintering raw material C is started. After 140 seconds, the granulated product AAB was added to the granulator c. The granulated product CC after completion of granulation contained 3% by mass to 5% by mass of 0.5 mm under fine powder, and the water content was 5% by mass to 10% by mass.

  The test results are shown in FIGS. In the figure, ◇ indicates the result of charging the granulated product AA having a moisture content of 10% by mass or 13% by mass into the granulating apparatus c without mixing it with the sintering raw material B.

The figure shows the following.
As the moisture difference between the granulated product AAB and the granulated product CC being granulated becomes smaller, the yield after baking in the pot improves. In particular, when the moisture difference between the granulated product AAB and the granulated product CC during granulation is 3% by mass or less, the yield after baking in the pot is remarkably improved. This is probably because the difference in moisture between the granulated product AAB and the granulated product CC became smaller, and the lack of firing due to uneven baking was suppressed.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the configurations described in the above-described embodiments, and is considered within the scope of the matters described in the claims. Other embodiments and modifications are also included. For example, in the above embodiment, a pan pelletizer is used as a mixer, but the present invention is not limited to this, and a drum mixer or the like may be used.

10: Granulator a, 11: Granulator c, 12: Mixer

Claims (3)

The sintered raw material A containing 15% by mass or more of fine powder of 500 μm or less is granulated with a moisture of 10% by mass to 13% by mass to obtain a granulated product AA,
The granulated product AA is mixed with a sintering raw material B having a moisture content of 0% by mass to 9% by mass to obtain a granulated product AAB.
A pretreatment method for a sintered raw material, comprising adding the granulated product AAB to a granulated product CC obtained by granulating a sintered raw material C containing iron ore and a coagulant. The sintered raw material A containing 15% by mass or more of fine powder of 500 μm or less is granulated with a moisture of 10% by mass to 13% by mass to obtain a granulated product AA,
The granulated product AA is mixed with a sintering raw material B having a moisture content of 0% by mass to 9% by mass to obtain a granulated product AAB.
The sintered raw material C containing iron ore and a coagulant is charged into a granulator and granulated for 120 seconds or more to obtain a granulated product CC having a water content of 5% by mass to 9% by mass. A pretreatment method for a sintering raw material, wherein the granulated product AAB is added to the material.   3. The pretreatment method for a sintered material according to claim 1, wherein a moisture difference between the granulated product AAB and the granulated product CC is 3 mass% or less. 4.

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