JP5043533B2 - Method for drying humidified dust and method for producing reduced iron - Google Patents

Description

  The present invention relates to a method for drying humidified dust and a method for producing reduced iron.

  There is a known method for producing reduced iron, in which converter dust collection dust is mixed with blast furnace dust and then agglomerated to form an agglomerate, which is then heated and reduced on a continuously moving hearth. (For example, refer to Patent Document 1).

  There has also been proposed a method in which wet dust generated in a steelmaking process is forcibly dried by sun-drying and classified for each purpose of use and then reused (for example, see Patent Document 2).

Japanese Patent No. 3723521 JP-A-7-113126

  By the way, an attempt has been made to transport M-Fe low dust (for example, secondary ash of a blast furnace, etc.) generated in other steelworks by sea or the like and reuse it as an iron source. When transporting, in order to prevent dust generation, the water content of the dust is hydrated to be about 13 to 17%, mixed with dust generated from the converter at the steel mill of the transport destination, Used as iron source for the production of reduced iron.

  However, the inventions described in Patent Document 1 and Patent Document 2 do not refer to a detailed mixing method of the humidified dust with low M-Fe water and the dust generated from the converter. Thus, there has been a demand for a method capable of producing reduced iron having a high metallization rate by adjusting the water content.

  Therefore, the present invention has been made in view of such problems, and an object of the present invention is to provide a new and improved method for drying humidified dust, which can improve the pulverization properties of the humidified dust, and the humidified dust. It is in providing the manufacturing method of the used reduced iron.

  In order to solve the above-mentioned problem, according to an aspect of the present invention, there is provided a method for drying humidified dust, which is a humidified dust that has been subjected to water treatment, and is added to a moisture content of 13 to 17%. The humidified dust having M-Fe of less than 5% and the converter dust having M-Fe of 5% or more are mixed to form mixed dust, and the moisture content of the mixed dust is set to 10% or less. A method for drying humidified dust is provided.

  The converter dust having 5% or more of M-Fe may have a reduced moisture content by oxidation heat generated by sun drying.

  The converter dust having 5% or more of M-Fe may have a moisture content of 5% or less.

  The humidified dust and the converter dust in which the M-Fe is 5% or more may be mixed at a mass ratio of 1: 1 to 1: 2.

  The particle size of the humidified dust may be smaller than the particle size of the converter dust in which the M-Fe is 5% or more.

  In order to solve the above-mentioned problems, according to another aspect of the present invention, using humidified dust that is dust subjected to water treatment, the metallization rate is 80% or more and the DRI productization rate is 65% or more. A reduced iron production method for producing reduced iron in which the moisture content is 13 to 17% and the humidified dust is less than 5%, and the M-Fe is 5% or more. Furnace dust, mixed dust to make a mixed dust, the moisture content of the mixed dust is 10% or less, a reducing material is blended in the mixed dust, the reduced iron raw material, There is provided a method for producing reduced iron, comprising a step of pulverizing a raw material, agglomerating the pulverized raw material, and drying and reducing the agglomerated raw material.

  In the step of pulverizing the raw material, the particle size of the raw material after pulverization may be set to 500 μm or less with an 80% under-sieving particle size.

  In the step of blending the reducing material with the mixed dust, the reducing material may be blended so that the moisture content of the reduced iron raw material after addition of the reducing material is 10% or less.

  82-93: 7-18 may be sufficient as the mass compounding ratio of the said mixed dust and the said reducing material.

  By the humidified dust drying method according to the present invention, it is possible to improve the grindability of the humidified dust. By producing reduced iron using this humidified dust, the metallization rate of the produced reduced iron is improved. It is possible to make it.

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

  In the following description, a case where a ball mill which is a kind of vibration mill is used as a pulverizer will be described in detail. However, the present invention is not limited to the case where a ball mill is used. It goes without saying that may be used as a grinder.

<About humidified dust and converter dust>
First, prior to describing a preferred embodiment of the present invention, humidified dust and converter dust used in the present invention will be described in detail with reference to FIG. Here, the humidified dust means dust that has been subjected to a hydration treatment. FIG. 3 is a graph for explaining changes in moisture content of humidified dust and converter dust. FIG. 4 is a graph for explaining the relationship between the ball mill outlet side particle size and the metallization rate of reduced iron. FIG. 5 is a graph for explaining the relationship between the ball mill outlet water content and the moisture correction coefficient, and FIG. 6 explains the relationship between the ball mill processing speed and the outlet raw material particle size. FIG.

  Conventionally, the humidified dust in which the moisture transported by sea is added to 13 to 17% is mixed with the converter dust at the transport destination, adjusted to a moisture content of 15%, and then pulverized and reduced. It was. In this case, the particle size of the dust after pulverization is about 1920 μm, and the metallization rate of reduced iron (hereinafter, also referred to as DRI) manufactured using this dust is about 49.6%, which is low quality. It was a thing.

  Therefore, the inventors of the present application first examined in detail the humidified dust as a raw material and the moisture content of the converter dust mixed with the humidified dust and the change thereof. Here, the humidified dust is dust having a water content of 13 to 17% and M-Fe of less than 5%.

  FIG. 3 shows changes in the moisture content of the humidified dust transported and the converter dust generated at the steel mill at the transport destination. Here, A dust in the figure represents humidified dust having a water content of 13 to 17% and M-Fe of less than 5%, and B dust in the figure is generated at the steel mill at the transport destination. Converter dust. Moreover, the vertical axis | shaft of FIG. 3 represents the moisture content rate (%) of each dust, and a horizontal axis is the elapsed days (A dust) which started from the day of water addition, and the elapsed days (A dust) which started from the generation | occurrence | production day ( B dust). A dust and B dust are conveyed to the yard and are sun-dried. Hereinafter, drying the dust in the sun in the yard is referred to as “curing”.

  Referring to FIG. 3, it can be seen that even when A dust is cured for 60 days, the water content does not decrease, but rather the water content increases due to the influence of rainfall or the like. On the other hand, it can be seen that the moisture content of B dust is remarkably lowered by curing for about 30 days, and the moisture content is reduced to around 0%. This is because the B dust at the time of generation has 20% or more of M-Fe, so that the dust itself generates heat by oxidation due to sun drying, and the moisture content decreases. In addition, the dust in which the moisture content has decreased due to oxidation heat generation will also reduce M-Fe to 10% or less. On the other hand, since the humidified dust has M-Fe of less than 5%, even if it is sun-dried, no oxidation heat is generated, and the moisture content does not decrease.

  FIG. 1 shown below shows the chemical components and the moisture content of dust different from the A dust and B dust shown in FIG. The converter dust (B dust) shown in Table 1 also shows the values before and after curing for 30 days.

  As is clear from Table 1, the converter dust generated at about 19.2% of M-Fe has a moisture content of 22% to 4.4, although M-Fe is reduced to 9.5% by curing. It greatly decreases to 6%.

<Relationship between particle size of mixed dust after grinding and metallization rate of reduced iron>
Next, the relationship between the particle size of the mixed dust after pulverization and the metallization rate of reduced iron will be described in detail with reference to FIGS. FIG. 4 is a graph for explaining the relationship between the ball mill outlet side particle size and the reduced iron metallization rate, and FIG. 5 is for explaining the relationship between the ball mill outlet side water content and the moisture correction coefficient. FIG. 6 is a graph for explaining the relationship between the ball mill processing speed and the particle size of the outgoing side raw material.

  It is known that the particle size of the mixed dust on the exit side (that is, after pulverization) of a ball mill used as a pulverizer and the metallization ratio of reduced iron have a relationship as shown in FIG. The horizontal axis in FIG. 4 is the particle size (μm) of the mixed dust on the ball mill exit side, and the vertical axis is the metallization rate of reduced iron.

  Referring to FIG. 4, it can be seen that the metallization rate of reduced iron increases as the ball mill exit side particle size decreases. FIG. 4 shows that in order to produce reduced iron with a high metallization rate such that the metallization rate is 80% or more, the ball mill outlet side particle size must be about 500 μm or less.

  Here, with respect to the grindability of the ball mill, it is known that the theoretical formula shown in the following formula 1 holds.

Here, in Equation 1 above,
F ₈₀ [μm]: 80% particle size under sieve on the ball mill entry side P ₈₀ [μm]: 80% particle size under sieve on the ball mill exit side W [kW]: Ball mill power, (350)
W _i [kWh / t]: Grinding work index, (Dust: 14.2, Coal: 28.6)
Q [wet-t / h]: Ball mill processing speed C ₁ [-]: Ball mill diameter correction coefficient, (0.88)
C ₂ [−]: dry correction coefficient, (1.3)
C ₃ [−]: Fine grinding correction coefficient, (1)
C ₄ [−]: Oversupply correction coefficient, (1)
C ₅ [−]: open circuit coefficient, (1.3)
C ₆ [−]: Correction coefficient. The numbers in () are the values actually substituted into Equation 1. The 80% particle size under the sieve means the particle size when the powder passing through the sieve becomes 80% of the total mass when sieving is performed.

The C ₁ and W _i can be calculated by the following formulas 2 and 3. Here, in Equation 2 below, D is the inner diameter (m) of the ball mill, and in Equation 3, HGI is the grindability index (Hard Globe Index, dimensionless amount).

In addition, the correction coefficient C ₆ having no physical meaning in the above formula 1 has a relationship as shown in FIG. 5 with respect to the moisture content of dust on the ball mill exit side, based on the results of the basic investigation on the actual ball mill. I found. As is apparent from FIG. 5, the correction coefficient C ₆ it is seen that a small value in the case of a low water content in the ball mill exit side. When an approximate curve of each point plotted in FIG. 5 is obtained, the following equation 4 is obtained when the moisture content on the exit side of the ball mill is x (%) and the value of the correction coefficient is y.

  Here, when the relationship between the ball mill processing speed Q and the 80% particle size under the sieve on the exit side of the ball mill is obtained using Equation 3 and Equation 4, the solid line shown in FIG. 6 is obtained. Here, the solid lines in FIG. 6 are theoretical curves when the moisture content on the exit side of the ball mill is 1%, 2%, 3%, 5%, and 7%, respectively. FIG. 6 also plots the relationship between the ball mill processing speed and the 80% particle size under the sieve on the exit side of the ball mill when an actual machine test is performed. In addition, the numerical value described in each plot is the moisture content on the exit side of the ball mill.

  Referring to FIG. 6, it can be seen that the plots obtained in the actual machine test under the respective conditions are in good agreement with the theoretical curves calculated based on Equation 3 and Equation 4. In addition, it can be seen from FIG. 6 that the processing speed of the ball mill can be increased by reducing the moisture content on the exit side of the ball mill.

  As described with reference to FIG. 4, in order to maintain a particle diameter of 500 μm or less on the exit side of the ball mill and to maintain a certain ball mill processing speed, it is clear from FIG. 6 that moisture content is present on the exit side of the ball mill. It can be seen that the rate needs to be 7% or less. Further, in order for the moisture content on the exit side of the ball mill to be 7% or less, it is considered that the moisture content on the entry side of the ball mill needs to be at least 10% or less.

<About the drying method of the humidified dust which concerns on this embodiment>
The method for drying humidified dust according to the present embodiment is based on the above knowledge, and does not generate oxidation heat even after curing, and humidified dust (A dust) that does not dry as it is, M-Fe is generated at about 19%, and it is dried by mixing with converter dust (B dust) in which M-Fe is about 10% and moisture content is 5% or less due to oxidation heat generated by curing. The water content of the mixed dust after mixing is reduced to 10% or less without using a machine or the like.

  Below, the drying method of the humidified dust which concerns on this embodiment is demonstrated in detail, referring FIG. FIG. 1 is an explanatory diagram for explaining a humidifying dust drying method according to the present embodiment.

  The humidifying dust drying method according to the present embodiment cures the converter dust 11 generated with M-Fe of about 19% by oxidizing and heat-generating by sun drying, and M-Fe is about 10%. The converter dust 13 after curing with a moisture content of 5% or less is obtained. The converter dust 13 after the curing is mixed with the humidified dust 15 having a water content of 13 to 17% and M-Fe of less than 5%, whereby the mixed dust 17 is obtained.

  Here, the specific gravity of the converter dust 13 after curing and the humidified dust 15 is about 1.8, and the particle size of the humidified dust 15 is smaller than the particle size of the converter dust 13 after curing.

  The converter dust 13 (B dust) and the humidified dust 15 (A dust) after curing may be mixed so that the mass ratio becomes 1: 1, for example. When the converter dust 13 and the humidified dust 15 after the curing are mixed to become the mixed dust 17, the moisture content of the humidified dust 15 decreases, and the moisture content of the entire mixed dust 17 becomes 10% or less.

  The mixed dust 17 is preferably used as a raw material for producing reduced iron without curing. By using the mixed dust 17 without curing, it is possible to eliminate the influence of weather such as rain, and it is used as a raw material for the production of reduced iron without increasing the reduced water content again. can do.

  The mixed dust 17 is agitated by vibration caused by conveyance while being conveyed for performing a pulverization step described later, and further agitated by loading and unloading during conveyance, so that A dust and B dust are uniform. To become distributed.

  As described above, by using the humidified dust drying method according to the present embodiment, the moisture content is 13 to 17% and M-Fe is less than 5% without using equipment such as a dryer. It is possible to reduce the moisture content of the humidified dust, and it is possible to produce a mixed dust having a moisture content of 10% or less. Since the mixed dust has a water content of 10% or less, as described above, it is possible to improve the pulverization property of dust in a ball mill as a pulverizer, and the raw material dust used as a raw material of reduced iron It is possible to reduce the size.

<About the manufacturing method of reduced iron>
Next, a method for producing reduced iron having a high metallization rate using the mixed dust produced using the drying method will be described in detail with reference to FIG. FIG. 2 is an explanatory diagram for explaining a method for producing reduced iron according to the present embodiment.

  As shown in FIG. 2, the method for producing reduced iron according to the present embodiment includes the converter dust 13 after curing in which M-Fe is about 10% and the moisture content is 5% or less, and moisture. The step of manufacturing the mixed dust 17 by mixing the humidified dust 15 which is hydrated to a content of 13 to 17% and M-Fe is less than 5%, and the mixed dust 17 and the reducing material 19 into the blending tank 20. And a step of charging the mixed dust 17 and the reducing material 19 from the mixing tank 20 so as to have a predetermined mixing ratio to be a raw material of reduced iron, and the obtained raw material is a kind of pulverizer. A step of pulverizing with the ball mill 30, a step of agglomerating the pulverized raw material with a granulator 40, a step of drying the agglomerated raw material with a dryer 50, and a rotary hearth furnace with the dried raw material (RHF) 60 is charged, heated and reduced to produce reduced iron And a step, a.

  Here, the process of manufacturing the mixed dust 17 mixes the humidified dust 15 and the converter dust 13 after curing using the above-described humidified dust drying method, and the moisture content of the humidified dust 15 is 10%. This is a step of lowering and making the mixed dust 17 as follows.

  In the process of charging the mixed dust 17 and the reducing material 19 into the blending tank 20, the mixed dust 17 manufactured in the yard or the like, and coal, coke, char, oil coke, waste plastic, Each of the reducing materials 19 such as waste tires is transported and charged into the blending tank 20. In this conveyance process, the converter dust 13 and the humidified dust 15 after curing are agitated by vibration during conveyance and become a uniform mixed dust 17.

  In the process of producing the reduced iron raw material, the mixed dust 17 and the reducing material 19 are taken out from the mixing tank 20 in which the mixed dust 17 and the reducing material 19 are respectively charged so as to obtain a predetermined mass mixing ratio, and are mixed. The raw material for reduced iron. Further, the blending ratio of the mixed dust 17 and the reducing material 19 is adjusted in consideration of suitable conditions for obtaining good reduced iron in the reduction step described later. The manufactured raw material is conveyed to the ball mill 20 described later.

  The pulverizing step in the ball mill 30 is a step of mixing and pulverizing the manufactured raw materials to refine them. Since the mixed dust 17 according to the present embodiment has a moisture content as low as 10% or less as described above, the ball mill processing speed is set to an appropriate processing speed with reference to FIG. The 80% particle size under sieve on the exit side can be 500 μm or less. Specifically, the processing speed of the ball mill can be determined from the target value of the particle size on the outlet side of the ball mill and the theoretical curve of the target value of the moisture content on the outlet side of the vibration mill. In addition, you may knead | mix and humidity-control the raw material which became 500 micrometers or less, for example with the mix muller etc.

  In the method for producing reduced iron according to the present embodiment, since the particle size of the raw material after pulverization is such that the metallization rate is 80% or more during the reduction treatment, the mixture after pulverization is used. By using it, it is possible to produce reduced iron with a high metallization rate.

  In the step of agglomerating the raw material, the raw material having a particle diameter of 500 μm or less is agglomerated by the granulator 40 to produce an agglomerate. The produced agglomerate is conveyed to the dryer 50 and dried to a predetermined moisture content (for example, less than 1%). The agglomerated material refers to pellets, briquettes, extruded products that are cut by extrusion molding, and granular materials such as agglomerated materials that have been adjusted in particle size.

  The agglomerate dried to a predetermined moisture content is charged into a rotary hearth furnace (RHF) 60, heated and reduced, and reduced iron. In the RHF 60, the floor portion in the furnace is rotated, and the agglomerate charged in the RHF 60 is heated and reduced while making a round in the RHF at a predetermined speed to be reduced iron (DRI). . The moving speed and the heating temperature in the RHF can be set as appropriate, but may be set so as to make one round in the RHF 60 at about 1350 ° C. for about 15 minutes.

  In the method for producing reduced iron according to the present embodiment, since the moisture content of the mixed dust 17 which is one of the raw materials of reduced iron is dried to 10% or less, the 80% particle size under the sieve on the ball mill exit side. Can be made 500 μm or less. Therefore, by using the mixed dust 17 as a raw material, the metallization rate of the manufactured DRI can be increased to 80% or more as shown in FIG. 4, for example.

  Hereinafter, the method for drying humidified dust and the method for producing reduced iron according to the present invention will be further described with reference to Examples and Comparative Examples. The following embodiment is merely a specific example of the present invention, and the present invention is not limited to the embodiment described below.

(Manufacture of humidified dust)
Humidified dust (A dust) having a water content of 13 to 17%, M-Fe less than 5%, M-Fe is about 10%, and the water content is 5%. The mixed dust was produced by mixing the converter dust (B dust) after curing which became less than or equal to% (see Table 1). The blending ratio of B dust and the number of days of curing after mixing are as shown in Table 2 below. In Table 2 shown below, the case where the blending ratio of B dust is 0 means that only A dust (A dust 100%) is used.

  As shown in Table 2, in the case of only A dust (No. 1 and No. 2 in Table 2), it is not dried by curing, and conversely, the moisture rises due to the influence of rainfall or the like. Moreover, in the case of only B dust (No. 6 and No. 7 of Table 2), it turns out that the moisture content has fallen conversely by curing.

  Further, when A dust having a moisture content of 14.7% and B dust having a moisture content of 4.6% are mixed at a mixing ratio of 1: 1, It can be seen that the moisture content is 9.7% (No. 4 in Table 2), which is 10% or less. Similarly, when A dust and B dust are mixed at a mixing ratio of 1: 2, the moisture content of the mixed dust becomes 8.0% (No. 5 in Table 2) and 10% or less when not cured. You can see that In addition, when cured (No. 3 in Table 2), the moisture content is slightly deteriorated to 11.0% due to the influence of rainfall or the like.

(Manufacture of reduced iron)
Subsequently, No. 1 shown in Table 2 was obtained. 1-No. Using the mixed dust of No. 7, reduced iron (DRI) was produced by the above-described process. In the example shown below, coal was used as the reducing material. The mixing ratio of the mixed dust and the reducing material and the moisture content of coal as the reducing material are as shown in Table 3 below. Table 4 below shows the moisture content on the ball mill entry side, the 80% particle size under sieve on the ball mill exit side, the DRI metalization rate, and the DRI product rate.

  Here, in Table 4 above, the DRI product rate is the ratio (%) of the total mass of briquettes charged into the RHF, although the mass after the reduction was 20 mm or more. Such a DRI product rate corresponds to the rate at which the inserted briquette did not explode in the RHF. In Table 4 above, “ball mill grindability” was evaluated as “◯” when the ball mill exit side particle size was 500 μm or less, and “x” when it exceeded 500 μm. In addition, “RHF reducibility” was evaluated as “◯” when the DRI metallization rate was 80% or more, and “X” when it was less than 80%. In addition, “DRI shape” indicates that the DRI product rate was 65% or more, and ○ was less than 65%.

  Referring to Table 4, the moisture content of the mixed dust exceeded 10%. 1-No. 3 shows that the moisture content exceeds 10% even on the ball mill entry side, and the 80% particle size under the sieve on the ball mill exit side also exceeds 500 μm. Therefore, the particle size on the ball mill exit side was over 1000 μm. 1-No. No. 3, the metallization rate of DRI is 70% or less, and the DRI product rate is as low as less than 65%.

  Moreover, No. in which the moisture content of the mixed dust was 10% or less. 4-No. 7 shows that the moisture content is 10% or less on the ball mill entry side, and the particle size on the ball mill exit side is 500 μm or less. Therefore, it can be seen that the metallization rate of DRI is also over 80%, and the product rate is as good as 65% or more.

  As described above, according to the present invention, it is possible to reduce the moisture content of the humidified dust which is watered to a moisture content of 13 to 17% and is less than 5% of M-Fe to 10% or less. It is possible to reduce the water content by about 5% by mixing with converter dust after curing at a blending ratio of 1: 1 to 1: 2. Moreover, by not curing, it is possible to avoid an increase in water content due to the influence of rainfall or the like.

  The mixed dust produced in this way can be refined to 500 μm or less, and by using such mixed dust as a raw material for reduced iron, the metallization rate is 80% or more and the DRI product rate is high. It is possible to produce high-quality reduced iron that is 65% or more.

  As mentioned above, although preferred embodiment of this invention was described referring an accompanying drawing, it cannot be overemphasized that this invention is not limited to this example. It will be apparent to those skilled in the art that various changes and modifications can be made within the scope of the claims, and these are naturally within the technical scope of the present invention. Understood.

It is a schematic diagram for demonstrating the drying method of the humidified dust which concerns on the same embodiment. It is explanatory drawing for demonstrating the manufacturing method of the reduced iron which concerns on one Embodiment of this invention. It is a graph for demonstrating the change of the moisture content of humidified dust and converter dust. It is a graph for demonstrating the relationship between a ball mill exit side particle size, and the metallization rate of reduced iron. It is a graph for demonstrating the relationship between a ball mill exit side moisture content and a moisture correction coefficient. It is a graph for demonstrating the relationship between a ball mill processing speed and the particle size of a ball mill exit side raw material.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Converter dust 13 Converter dust after curing 15 Humidified dust 17 Mixed dust 19 Reducing material 20 Mixing tank 30 Ball mill 40 Granulator 50 Dryer 60 Rotary hearth furnace

Claims (8)

A method for drying humidified dust that dries humidified dust, which is dust that has been subjected to water treatment,
Mixing the humidified dust having a water content of 13 to 17% and M-Fe of less than 5% and the converter dust having M-Fe of 5% or more into mixed dust,
A method for drying humidified dust, wherein the moisture content of the mixed dust is 10% or less.   2. The method for drying humidified dust according to claim 1, wherein the converter dust having M-Fe of 5% or more has a reduced moisture content due to oxidation heat generated by sun drying. .   The method for drying humidified dust according to claim 2, wherein the converter dust having 5% or more of M-Fe has a moisture content of 5% or less.   The humidified dust according to claim 3, wherein the humidified dust and the converter dust having 5% or more of M-Fe are mixed at a mass ratio of 1: 1 to 1: 2. Drying method.   2. The method for drying humidified dust according to claim 1, wherein the particle size of the humidified dust is smaller than the particle size of the converter dust in which the M-Fe is 5% or more. A method for producing reduced iron that produces reduced iron having a metallization rate of 80% or more using humidified dust, which is dust that has been subjected to water treatment,
Mixing the humidified dust having a water content of 13 to 17% and M-Fe of less than 5% with the converter dust having M-Fe of 5% or more to obtain mixed dust, the mixed dust The step of setting the moisture content of
Mixing a reducing material with the mixed dust and using the reduced iron as a raw material;
Crushing the raw material;
Agglomerating the crushed raw material;
Drying and reducing the agglomerated raw material;
A method for producing reduced iron, comprising:   The method for producing reduced iron according to claim 6, wherein, by the step of pulverizing the raw material, the particle size of the raw material after pulverization is set to 500 μm or less with an 80% under-sieving particle size.   7. The step of blending the reducing material into the mixed dust is characterized in that the reducing material is blended so that the moisture content of the reduced iron raw material after addition of the reducing material is 10% or less. A method for producing reduced iron according to 1.

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