JP4178079B2 - Granular reduced metal production method and production apparatus thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention belongs to the field of technology for reducing granular reduced metal raw materials mainly composed of metal oxide and carbonaceous reducing material in a moving hearth furnace.
[0002]
In the following prior art, problems to be solved by the invention and embodiments of the invention, iron oxide, granular reduced iron raw material and reduced iron are exemplified as the metal oxide, granular reduced metal raw material and reduced metal, respectively. However, the present invention is not limited to this. In addition to iron (Fe), non-ferrous metal elements such as Mn, Ni, Cr, Mo, and Ti are also targeted as the metal elements contained in the metal oxide, granular reduced metal raw material, and reduced metal according to the present invention. In addition, those containing any plural kinds of these iron and non-ferrous metal elements are also targeted.
[0003]
[Prior art]
[Prior art 1]
Conventionally, a moving hearth furnace has been used to reduce pelletized or briquetted granular reduced iron raw materials mainly composed of iron oxide and a carbonaceous reducing material. When supplying granular reduced iron raw material to this moving hearth furnace, the granular reduced iron raw material granulated by the granulator is dried by a dryer, and the dried granular reduced iron raw material can be moved up and down, that is, can be moved up and down. It is supplied to the hearth of the moving hearth furnace through the configured vertical supply pipe, and this supply pipe is moved up and down to adjust the gap between the lower end of this supply pipe and the hearth, The thing which adjusted the supply amount of reduced iron raw material with high precision is disclosed (refer patent document 1).
[Prior art 2]
Further, the granular reduced iron raw material is supplied onto the hearth of the mobile hearth furnace through the raw material supply means, and the furnace is provided downstream of the raw material discharge port from which the granular reduced iron raw material is discharged from the raw material supply means. The granular reduced iron raw material on the floor is moved in the width direction of the hearth by rotating the spiral blades of the leveling machine (equalizing device), and the fluctuation of the supply amount of the raw granular reduced iron raw material is followed. Disclosed is a material in which the granular reduced iron raw material is reliably dispersed and leveled by raising and lowering the leveler so as to change the gap between the floor and the spiral blade of the leveling machine (Patent Document). (See 2.)
[0004]
[Prior art 3]
In addition, when reducing granular reduced iron raw material in a moving hearth furnace, uniform granular reduced iron is produced by setting 80% or more of the granular reduced iron raw material to be within ± 2 mm of the target particle size. Is disclosed (see Patent Document 3).
[0005]
[Patent Document 1]
Japanese Patent No. 3075722 [Patent Document 2]
Japanese Patent No. 3208385 [Patent Document 3]
Japanese Patent No. 3020494 [0006]
[Problems to be solved by the invention]
The granular reduced iron raw material is obtained, for example, by forming a mixed raw material mainly composed of powdered iron ore as an iron oxide source and powdered coal as a carbonaceous reducing material into pellets and briquettes. Here, since the pellet can be formed by rolling granulation using a granulator, the productivity is higher than that of a briquette that requires pressure molding using a briquette press or the like, and maintenance due to die wear or the like is not required. For this reason, the granular reduced iron raw material is generally produced as a pellet except when the granulated property of the mixed raw material is poor and pelletization is difficult.
[0007]
As a granulator for producing pellets, a bread-type pelletizer or a drum-type pelletizer is usually used. Regardless of which granulator is used, the pellets obtained have a wide particle size distribution due to the granulation principle. For reference, FIG. 4 shows a particle size distribution when a mixed raw material mainly composed of powdered iron ore and powdered coal is granulated into pellets by a pan-type pelletizer of a reduced iron manufacturing plant using a moving hearth furnace. A large number of polygonal lines in FIG. 4 indicate temporal fluctuations in the particle size distribution (note that the number of polygonal lines is large, and is shown separately in (a) and (b)). As shown in the figure, it can be seen that the particle size of the pellets is distributed over a wide range of about ± 5 to 10 mm centering on the average particle size, and the average particle size varies greatly with time.
[0008]
Here, as disclosed in the prior art 3, it is known that homogeneous granular reduced iron can be obtained if 80% or more of the granular reduced iron raw material is within ± 2 mm of the target particle size. However, when pellets are used as the granular reduced iron raw material, the pellet particle size is distributed over a wide range as described above, and the average particle size varies greatly. Therefore, only those having such a narrow particle size range are used. This is practically impossible considering the granulation yield. Here, the granulation yield refers to the ratio of the amount of pellets supplied to the moving hearth furnace out of the total granulation amount. That is, in the particle size distribution shown in FIG. 4, if only pellets having a diameter of, for example, 13 to 22 mm, which is more realistic than the above-described prior art 3, are used, the granulation yield varies from a little over 40% to about 90%. (See FIG. 5). Therefore, considering the granulation yield of more than 40%, which is the lower limit of the fluctuation range, the granulation capacity of the granulator (the total granulation capacity of multiple granulators when multiple granulators are installed in the actual plant) ) Requires a granulation capacity more than twice the amount of pellets required for reduction. Also, if a granulator with such a margin is installed, it is difficult to store due to the nature of raw pellets when the yield reaches about 90%. There is an urgent need to recycle the pellets of diameter as a surplus to the mixed material.
[0009]
Therefore, most of the reduced iron production plants using moving hearth furnaces do not have such an excessive margin in the granulation capacity of the granulator, and maintain a high yield by expanding the particle size range used. It is common to operate. In the granulator having the particle size distribution as shown in FIG. 4, the operation is performed by expanding the particle size range of the pellets used to about 9 to 25 mm or more (see FIG. 5).
[0010]
Here, by simulation calculation considering heat transfer and reduction reaction, pellets of a single particle size are laminated on the hearth in one layer, two layers, or three layers, respectively, and the atmosphere temperature is 1350 ° C. in the moving hearth furnace. FIG. 6 shows the relationship between the pellet particle size and the reduced iron productivity when reducing iron with a metallization rate of 90% is obtained by heat reduction. In the case of one layer or two layers, the productivity increases as the pellet particle size increases, and a productivity of about 150 kg / (m ² · h) is obtained at a particle size of 16 mm or more. On the other hand, in the case of three layers, the productivity reaches a peak at a particle size of 10 mm or more, and the productivity remains at about 100 kg / (m ² · h). This is presumably because in the case of three layers, the lowermost layer pellets are behind the upper two layer pellets and the effect of radiant heating from the atmosphere or the furnace wall is almost lost.
[0011]
Further, according to the above simulation calculation, reduced particles with a metalization rate of 92% can be obtained when pellets having a single particle size of 18 mm are laid on the hearth in one layer. Calculations were performed assuming that pellets having a diameter range of 9 to 25 mm were supplied onto the hearth by the methods of the prior arts 1 and 2 described above. In the prior arts 1 and 2, the pellets are laminated on the hearth with a substantially constant layer thickness. For this reason, the pellets with a single particle size of 10.5 mm are laminated in two layers, and the metallization ratio of the pellets on the lower layer side is about 75%, but the pellets with a single particle size of 9 mm are divided into three layers. A calculation result was obtained that the metallization rate of the laminated pellets of the lowermost layer was only about 40%.
[0012]
In order to supply pellets having a wide particle size range as described above to the hearth by the method of Prior Art 1, it is necessary to adjust the gap between the lower end of the supply pipe and the hearth to the maximum particle size of the pellets. There is. In addition, in order to level the above-mentioned pellet having a wide particle size range on the hearth by the method of Prior Art 2, the gap between the hearth and the spiral blade of the leveler is adjusted to the maximum particle size of the pellet. Need to be adjusted. For this reason, when the methods of the prior art 1 and 2 are used in actual operation, small particle size pellets are supplied to the gaps between large particle size pellets, or small particle size pellets are laminated in three or more layers. It was easy. For this reason, as predicted from the results of the above simulation calculation, when the productivity of reduced iron is maintained at a high level, the metallization rate of the small particle size pellets hidden behind the lower layer portion decreases, thereby reducing the reduced iron. As a result, the average metallization rate is lowered and the product quality is lowered. On the other hand, when maintaining the product quality, that is, to maintain the average metallization rate of reduced iron at the target metallization rate, if the residence time is extended to increase the metallization rate of the pellets in the lower layer, the productivity of reduced iron is increased. There was a problem that would be significantly reduced.
Also, when producing reduced dezincified iron by heating and reducing granular reduced iron material containing zinc oxide in a moving hearth furnace, maintain the reduced iron productivity at a high level for the same reason as above. Then, since the dezincification rate of the pellets having a small particle size in the lower layer portion is lowered, the average dezincification rate of the reduced iron is lowered and the product quality is lowered. On the other hand, when maintaining the product quality, that is, maintaining the average dezincification rate of the reduced iron at the target dezincification rate, increasing the residence time and increasing the dezincification rate of the pellets in the lower layer will reduce the productivity of reduced iron. There was a problem of a significant drop.
[0013]
Therefore, the present invention supplies pellets (granular reduced metal raw material) onto the hearth of a moving hearth furnace, and heats and reduces the granular reduced metal raw material on the hearth in the moving hearth furnace, An object of the present invention is to provide a method for producing a high-quality granular reduced metal with high productivity without reducing the granulation yield of pellets (granular reduced metal raw material). .
[0014]
[Means for Solving the Problems]
The invention according to claim 1 includes a raw material classification step of classifying the granular reduced metal raw material into a plurality of particle size ranges in advance by a raw material classification means, and a plurality of raw material supply means for each of the respective particle size ranges. , And separately supplying different regions in the width direction of the hearth moving in the moving hearth furnace, and the regions supplied with the finer particle size range of the different regions are on the hearth A raw material supply step of adjusting the raw material supply amount by the plurality of raw material supply means so that the raw material layer thickness is reduced, and the supplied granular reduced metal raw material passes through the moving hearth furnace along with the movement of the hearth. and a particulate reduced metal and forming a reducing process by reducing heating by said plurality of material supply means, respectively, provided with a supply pipe connected to the lower end opening as a raw material receiving hopper, said plurality of Fee adjustment of the material supply amount of the supply means, wherein a method for producing a granular reduced metal, which comprises carrying out by adjusting the lower and the furnace alcove gaps between the supply pipe.
[0016]
The invention according to claim 2 is a raw material classification step in which the granular reduced metal raw material is preliminarily classified into a plurality of particle size ranges by the raw material classification means, and a plurality of raw material supply means for each of the respective particle size ranges. The raw material supply step of supplying separately in different regions in the width direction of the hearth moving in the moving hearth furnace, and the region where the fine particle size range of the different regions is supplied, The gap between the hearth and the spiral blade of the leveling means is configured to be small, and by rotating the spiral blade, the granular reduced metal raw material on the hearth is dispersed in the width direction of the hearth. A raw material leveling step for leveling the granular reduced metal raw material on the hearth so that the thickness of the raw material layer on the hearth becomes smaller as the region in which the finer particle size range is supplied, and this leveled granularity Reduced metal raw material of the hearth A particulate reduced metal and form reduction step by with dynamic heated by passing through the moving hearth furnace reduction is a method for producing a granular reducing metal comprising the.
[0017]
According to a third aspect of the present invention, there is provided a raw material classifying means for classifying the granular reduced metal raw material into a plurality of particle size ranges in advance, and a hearth moving within the furnace for each of the classified particle size ranges. A plurality of raw material supply means for supplying separately into different regions in the width direction, a raw material supply means for supplying the granular reduced metal raw material onto the hearth moving in the furnace, and a fine particle size among the different regions The region to which the one in the range is supplied is configured such that the gap between the hearth and the spiral blade of the leveling means is reduced, and the granular reduced metal raw material on the hearth is rotated by rotating the spiral blade. By dispersing in the width direction of the hearth, the granular reduced metal raw material on the hearth is leveled so that the raw material layer thickness on the hearth becomes smaller in the region where the finer particle size range is supplied. Leveling means and this leveling A granular reduced metal production apparatus comprising: a moving hearth furnace which is converted into a granular reduced metal by passing the inside of the furnace floor with the movement of the hearth and reducing by heating and reducing the reduced metal raw material. .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In FIG. 1, the outline of the supply part of the granular reduced iron raw material which concerns on embodiment of this invention is shown. Here, reference numeral 1 is a roller screen as classification means, reference numeral 2 (21, 22, 23) is a raw material supply device as raw material supply means, reference numeral 3 is a moving hearth furnace, reference numeral 4 is a hearth, reference numeral 5 is leveling. A leveling device as a leveling means, 6 is a spiral blade provided in the leveling device 5.
[0019]
[Raw material classification step]: Pellets P as granular reduced iron raw materials mainly composed of iron oxide and a carbonaceous reducing agent dried by a drier not shown are supplied onto the roller screen 1 by the belt conveyor 11. The roller screen 1 is composed of a plurality of rotatable rollers as shown in the figure, and the roller interval on the dropping side (referred to as the front side) of the pellet P from the belt conveyor 11 is reduced, and the roller interval is increased toward the tip side. Keep it large and tilt it so that the tip side is lower than the near side. As a result, the pellets P supplied to the roller screen 1 are classified according to different particle size ranges sequentially from a small particle size pellet on the front side and a large particle size pellet on the front side according to the roller interval. In this embodiment, the pellets P are classified into three particle size ranges in the order of P1, P2, and P3 from the smaller particle size side.
[0020]
[Raw material supply step]: Below the roller screen 1, different regions R1 in the width direction of the hearth 4 in which the pellets P1, P2, P3 classified according to the particle diameter are individually moved in the moving hearth furnace 3. , R2 and R3, and raw material supply devices 21, 22, and 23 are provided. The hearth 4 of the moving hearth furnace 3 includes a circular type that rotates horizontally and a linear type that goes straight, but the type of the hearth 4 may be any type. Further, the pellet P may be supplied to the moving hearth furnace 3 as it is without being dried after granulation and may be reduced.
[0021]
The raw material supply device 21 supplies the raw material receiving hopper 21a that receives the pellets P1 classified and dropped from the roller screen 1, and supplies the pellets P1 received by the raw material receiving hopper 21a to the region R1 on the hearth 4 It consists of a pipe 21b. The material supply devices 22 and 23 have the same configuration as the material supply device 21.
[0022]
The roller screen 1 is installed along the width direction of the hearth 4 (that is, in a direction perpendicular to the moving direction of the hearth 4), and the raw material receiving hoppers 21a, 22a, 23a are positioned immediately below the roller screen 1. Therefore, the pellets P1, P2, and P3 are provided adjacent to the positions where the pellets P1 and P3 fall sequentially. And supply pipe 21b, 22b, 23b is connected to the lower end opening part of each raw material receiving hopper 21a, 22a, 23a, respectively, and pellet P1, P2, P3 is stably supplied to the lower end of supply pipe 21b, 22b, 23b. In order to be able to do so, it is installed with a gap of an appropriate size from the hearth 4. Thereby, the pellets P1, P2, and P3 having different particle size ranges are supplied separately from the lower ends of the supply pipes 21b, 22b, and 23b to the regions R1, R2, and R3 in the width direction on the hearth 4 different from each other. In this way, the pellets P1, P2, P3 having different particle size ranges are placed in different regions R1, R2, R3 in the width direction on the hearth 4 so that the small particle size pellet P1 has a large particle size. It is supplied to the gaps between the pellets P3 and is not shaded, and by adjusting the gap between the lower end of the supply pipe 21b and the hearth 3, only the supply amount of the small-diameter pellets P1 is adjusted independently. It is possible to easily prevent the pellets having a small particle diameter from being laminated in three or more layers.
[0023]
Moreover, in order to supply the raw material layer thickness on the hearth 4 to be smaller in the region where pellets having a finer particle size range are supplied, for example, between the supply pipes 21b, 22b, 23b and the hearth 3 What is necessary is just to enlarge each clearance gap sequentially in this order. Thereby, even if the particle size range of the original pellet P is wide, the raw material layer thickness can be changed for each pellet P1, P2, P3 of each particle size range, so that the pellet P1 having the finest particle size range is supplied. Also, the region R1 is not laminated in a multilayer of three or more layers, and can be two or less for every particle size range.
[0024]
[Raw material leveling step]: Further, a horizontal rotation axis along the width direction of the hearth 4 (that is, in a direction perpendicular to the hearth movement direction) downstream of the supply pipes 21b, 22b, and 23b in the hearth movement direction. 7 is provided with the leveling device 5 having the spiral blades 6, and the gap between the hearth 4 and the spiral blades 6 of the leveling device 5 is increased in the region where the finer particle size range is supplied. You may comprise so that it may become small. As a result, the pellets P1, P2, and P3 supplied onto the hearth 4 by the supply pipes 21b, 22b, and 23b move in the width direction of the hearth 4 along with the rotation of the spiral blade 6 and are leveled. The thickness of the raw material layer on the hearth 4 can be reduced in the region where pellets having a fine particle size range are supplied.
[0025]
In order to reduce the gap between the hearth 4 and the spiral blade 6 of the leveling device 5 in the region where the finer particle size range is supplied, for example, as shown in FIG. The leveling device 5 having a spiral blade 6 having a constant outer diameter is similar to the above, and the rotating shaft 7 is not horizontal (that is, not parallel to the hearth 4), and has a fine particle size range. The region R1 to be supplied may be inclined and installed so as to be lower than the region R3 in which the coarser particle size range is supplied.
[0026]
Alternatively, although not shown in the drawing, the outer diameter of the spiral blade 6 is increased as the region to which the fine particle size is supplied is different from the prior art 2, and the rotating shaft 7 is the same as the prior art 2. It can also be installed horizontally (that is, parallel to the hearth 4).
[0027]
Thus, the pellet P1 having the finest particle size range is supplied by leveling the raw material layer thickness on the hearth 4 to be smaller in the region where the fine particle size range pellets are supplied. Even in the region R1, there is no lamination of three or more layers, and two or less layers are ensured for every particle size range.
[0028]
[Reduction step]: By passing the pellets P1, P2, P3, which have been leveled into two or less layers, through the moving hearth furnace 3 in a high temperature atmosphere together with the movement of the hearth 4, the pellets P1, P2, P3 are Since it is rapidly heated and reduced to the lower layer, granular reduced iron having a high metallization rate can be obtained with high productivity.
[0029]
In the above embodiment, the case of classification into three particle size ranges has been described. However, the present invention is not limited to this, and the number of classifications can be changed as appropriate according to the width of the hearth 4 and the like. Further, it is desirable that the roller interval of the roller screen 1 be adjustable so as to be able to cope with a change / fluctuation in the particle size distribution of the supplied pellets. Further, in FIG. 1, no partition wall is provided between adjacent raw material receiving hoppers (between 21a and 22a, and between 22a and 23a), but this is not restrictive, so that pellets having different particle size ranges are not mixed. It is also preferable to provide a partition wall. In FIG. 1, the supply pipes 21b, 22b, and 23b are installed in a direction perpendicular to the hearth 4. However, the present invention is not limited to this, and the positions of the roller screen 1 and the raw material receiving hoppers 21a, 22a, and 23a and the hearth 4 to be supplied. Depending on the positional relationship with the upper regions R1, R2, R3, etc., they may be inclined. It is also desirable that the supply pipes 21b, 22b, 23b and the leveling device 5 are configured to be movable up and down so that the gap with the hearth 4 can be adjusted in response to fluctuations in the particle size distribution of the supplied pellets. (See the prior arts 1 and 2 above).
[0030]
【Example】
[Example]
A reduced iron production test was conducted using a reduced iron production facility using a rotary hearth furnace (moving hearth furnace) having a charging section having the configuration shown in FIG. In FIG. 1, the left side of the drawing shows the outer peripheral side of the rotary hearth furnace 3. The roller interval of the roller screen 1 is adjusted to three types of 9 to 18 mm, 18 to 21 mm, and 21 to 25 mm from the outlet side of the pellet P, and the pellets P1, P2, and P3 classified into these respective particle size ranges are used as raw materials. It was made to supply to different area | region R1, R2, R3 on a hearth via receiving hopper 21a, 22a, 23a and supply pipe 21b, 22b, 23b. The three types of particle size ranges are set so that the supply amounts of the pellets P1, P2, and P3 in each particle size range are substantially equal. And the rotating shaft 7 of the leveler (equalizing device) provided with the spiral blade 6 having a constant outer diameter is inclined from the horizontal so that the gap between the hearth 4 and the spiral blade 6 is the outer peripheral side of the rotary hearth furnace 3. (Left side of the drawing) was adjusted to be 21 mm at the position 1/3 of the width of the hearth 4 and 25 mm at the position 2/3.
[0031]
[Comparative example]
In FIG. 1, the roller screen 1 is not provided, the raw material supply apparatus is installed only in the middle (reference numeral 22) in FIG. 1, and the leveler (equalizing apparatus) 5 having a spiral blade 6 having a constant outer diameter is a furnace. It installed horizontally so that the clearance gap between the floor 4 and the spiral blade | wing 6 might become fixed 25 mm.
[0032]
[Reduction test results]
The pellet P of 9 to 25 mm obtained by granulating with a pan-type pelletizer and then dried with a dryer is supplied to the rotary hearth furnace 3 using the equipment of the above-mentioned examples and comparative examples, and a reduction test is performed. It was. The atmospheric temperature in the rotary hearth furnace 3 was set to 1350 ° C.
[0033]
FIG. 2 and FIG. 3 schematically show the stacked state of the pellets in the cross section in the width direction of the hearth 4 when charged with the facilities of the above-described examples and comparative examples.
[0034]
As is apparent from FIG. 2, when supplied by the equipment of the above-described embodiment, the pellets are averaged in one layer in the region R2 having a particle size range of 18 to 21 mm and the region R3 having a particle size range of 21 to 25 mm. In the region R1 having a particle size range of 9 to 18 mm, the pellets with a particle size close to 18 mm are leveled into one layer, and the pellets with a particle size close to 9 mm are leveled into two layers.
[0035]
On the other hand, as seen in FIG. 3, when supplied by the equipment of the above comparative example, the small particle size pellets close to 9 mm are in the gaps between the large particle size pellets of 18 to 25 mm particle size. It can be seen that it exists or is laminated in three layers.
[0036]
In the above example, when the pellet residence time in the furnace was 8 min, the metallization rate of the pellets in the region R3 was about 83%, but the pellets in the regions R1 and R2 had a high metallization rate of about 93%. As a result, a high metallization rate of about 90% was obtained on the average of the total reduced iron. The productivity at this time was 125 to 130 kg / (m ² · h), and high productivity could be maintained.
[0037]
On the other hand, when the residence time of the pellets in the furnace in the comparative example was set to 8 min, which was the same as that in the above example, the metallization rate of the pellets having a particle diameter of 21 to 25 mm existing in the region corresponding to the region R3 in the above example was Although it was around 83% as in the above example, the metallization rate of the pellets having a small particle size close to 9 mm in the gaps between the large particle size pellets and the three-layered portion was about 75. %, And the average total reduced iron was less than 80%. Further, in order to improve the quality of the reduced iron, if the residence time of the pellets in the furnace is extended so that an average metallization rate of 90% of the entire reduced iron is obtained, the productivity is about 100 kg / (m ²・ It was necessary to reduce to h).
[0038]
In addition, the granulation yield was able to achieve 90% or more on a time average in both the above Examples and Comparative Examples.
[0039]
【The invention's effect】
As described above, according to the present invention, pellets (granular reduced metal raw material) are supplied onto the hearth of the moving hearth furnace, and the granular reduced metal raw material on the hearth is heated and reduced in the moving hearth furnace. In the method for producing granular reduced metal to be used as granular reduced metal, high quality granular reduced metal can be produced with high productivity without reducing the granulation yield of pellets (granular reduced metal raw material).
[Brief description of the drawings]
FIG. 1 is a vertical sectional view showing an outline of a supply portion of granular reduced iron raw material according to an embodiment of the present invention.
FIG. 2 is a vertical sectional view in the hearth width direction schematically showing a stacked state of pellets charged by the charging equipment of the example.
FIG. 3 is a vertical sectional view in the hearth width direction schematically showing a stacked state of pellets charged by a charging facility of a comparative example.
FIG. 4 is a graph showing the particle size distribution of pellets granulated with a bread-type pelletizer.
FIG. 5 is a graph showing fluctuations in granulation yield of pellets granulated with a bread-type pelletizer.
FIG. 6 is a graph showing the relationship between pellet particle size and reduced iron productivity.
[Explanation of symbols]
1 ... Raw material classification means (roller screen)
2, 21, 22, 23 ... Raw material supply means (raw material supply device)
21a, 22a, 23a ... Raw material receiving hoppers 21b, 22b, 23b ... supply pipe 3 ... moving hearth furnace 4 ... hearth 5 ... leveling means (equalizing device)
6 ... spiral blade 7 ... rotating shaft 11 ... belt conveyors P, P1, P2, P3 ... granular reduced metal raw material (pellet)
R1, R2, R3 ... region

Claims (3)

A raw material classification step of preliminarily classifying the granular reduced metal raw material into a plurality of particle size ranges by a raw material classification means;
For each of the respective particle size ranges, a plurality of raw material supply means are used to separately supply different regions in the width direction of the hearth moving in the moving hearth furnace, and the particle size of the different regions A raw material supply step of adjusting a raw material supply amount by the plurality of raw material supply means so that a raw material layer thickness on the hearth becomes smaller as a region in which a fine particle size range is supplied,
A reduction step of converting the supplied granular reduced metal raw material into a granular reduced metal by passing the inside of the moving hearth furnace with the movement of the hearth and heating and reducing,
Equipped with a,
Each of the plurality of raw material supply means includes a raw material receiving hopper and a supply pipe connected to the lower end opening thereof, and the adjustment of the raw material supply amount by the plurality of raw material supply means is adjusted to the lower end of each of the supply pipes and the furnace. A method for producing a granular reduced metal, which is performed by adjusting a gap between floors . A raw material classification step of preliminarily classifying the granular reduced metal raw material into a plurality of particle size ranges by a raw material classification means;
A raw material supply step for supplying each of the respective particle size ranges separately into different regions in the width direction of the hearth moving in the moving hearth furnace through a plurality of raw material supply means,
The region in which the finer particle size in the different region is supplied is configured such that the gap between the hearth and the spiral blade of the leveling means is reduced, and the spiral blade is rotated. By dispersing the granular reduced metal raw material on the hearth in the width direction of the hearth, the raw material layer thickness on the hearth becomes smaller in the region where the finer particle size range is supplied. A raw material leveling process for leveling the granular reduced metal raw material on the hearth;
A reduction step of converting the averaged granular reduced metal raw material into a granular reduced metal by passing the inside of the moving hearth furnace with the movement of the hearth and reducing by heating and reducing,
A method for producing a granular reduced metal, comprising: Raw material classification means for classifying the granular reduced metal raw material into a plurality of particle size ranges in advance,
A plurality of raw material supply means for separately supplying each of the classified particle size ranges divided into different regions in the width direction of the hearth moving in the furnace,
The region in which the finer particle size in the different region is supplied is configured such that the gap between the hearth and the spiral blade of the leveling means is reduced, and the spiral blade is rotated. By dispersing the granular reduced metal raw material on the hearth in the width direction of the hearth, the raw material layer thickness on the hearth becomes smaller in the region where the finer particle size range is supplied. Leveling means for leveling the granular reduced metal raw material on the hearth;
A moving hearth furnace that turns into a granular reduced metal by heating and reducing the averaged granular reduced metal raw material while passing through the furnace with the movement of the hearth;
An apparatus for producing a granular reduced metal, comprising:

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