1
Specification
BLAST FURNACE BOSH ZONE STRUCTURE AND METHOD OF DESIGNING OF
BLAST FURNACE BOSH ZONE
Field of the Invention
[0001]
The present invention relates to a blast furnace bosh zone structure and a method of designing the same.
Priority is claimed on Japanese Patent Application No. 2009-224434, filed September 29, 2009, the content of which is incorporated herein by reference.
Related Art
[0002]
In the past, the bosh Izone in a blast furnace had a sheet iron shell, a cooling stave provided inside the steel iron shell (hereinafter referred to simply as a stave), and a refractory brick that is provided inside the stave and protects the stave. A space between the sheet iron shell and the stave was appropriately filled with castable or the like. -
As the blast furnace operates, the iimer structure is wear-damaged in the bosh zone. Firstly, the refractory brick is wear-damaged, and, subsequently, even the stave is eroded. As the wear damage of the stave proceeds, the protection of the sheet iron shell becomes impossible, and the operating life of the bosh zone in the blast furnace ends due to deformation or cracking caused by the increased temperature of the sheet iron shell.
[0003]

2 In the blast furnace, operational management is carried out with vast amounts of
parameters taken into consideration so as to obtain an appropriate working state.
However, in many blast fumaces, the operational achievement changes significantly over
the campaign life, that is, approximately 15 years of operating life. Particularly, it is
known that, during several years from the begiiming of operation of the blast furnace
after blowing-in, a time period appears in which the operational achievement is
significantly decreased.
The decrease in the operational achievement of the blast furnace is considered to result from the fact that the structures on the inside surface of the blast fLimace, such as refractory bricks, are wear-damaged as the operation continues after the blowing-in, and the inside surface profile is changed.
That is, in the initial operational state inamediately after the blowing-in of the blast furnace, the inside surface shape is deterinined by the surfaces of the refractory bricks piled on the inside of the furnace. As time elapses from the beginning of the operation of the blast furnace, local wear damage proceeds in the refractory bricks. Thereby, the profile of the inside surface of the furnace (the contour shape appearing on a vertical cross section) becomes inappropriate, and there are cases in which the circumferential balance (the shape in the circumferential direction appearing on a horizontal cross section) becomes uneven-. In such a state as the surface shape in the blast furnace being inappropriate, gas flux, distribution of the contents, and the like in the furnace become unstable, which may cause degradation of the operational achievement.
[0004]
After such an unstable period ends, a phase in which the operation of the blast fiimace is stabilized follows. This is considered to be because the majority of the refractive bricks are lost, and an approximately appropriate profile or circumferential

3 balance, which is close to that in the initial phase of the blowing-m, is obtained by a
scaffolding layer generated on the inside surface of the stave.
From the blowing-in of the blast furnace to the operational stabilizing phase, a majority of the refractive bricks installed in the blast furnace are lost by thermal shock or wear damage. However, it is considered that a scaffolding layer derived from an accretion is generated on the inside surface of the stave, and the scaffolding layer compensates the wear-damaged portions-on the inside surface of the furnace (the self-lming effect).
In the blast furnace, the inside surfaces of, particularly, the bosh zone and a belly portion come into contact with the root portion of a high-temperature cohesive zone (an area in which ores m the accretion begin to be softened and melted, the ores in a semi-molten state are mutually fused, and connected into a sheet shape), and the surfaces are wear-damaged due to the high temperature. That is, since the root portion of the cohesive zone comes into contact with the stave main body, thermal load and wear damage occur ui the stave main body. The scaffolding generated on the stave surface in-the blast furnace in the operational stabilizing phase of the blast furnace has a protectmg action against the thermal load and wear damage, and repairs the lost portions in the refractive bricks in the furnace. It is considered that the stable operation for a longer time and operating Ufe improvement of the blast furnace becomes possible as long as an appropriate thickness of the scaffolding layer or an appropriate inside profile can be maintauied by the repair. . [0005]
Patent Document 1 is known as a technique for avoiding an inappropriate inside svirface profile or circumferential balance due to damage on the refractory bricks in the blast furnace. Patent Document 1 describes that refractory bricks are not installed on

4 the inside surface of the stave, and the inside surface of the stave is used as the inside
wall of the furnace body so that the shape of the inside surface is not changed due to
wear-damage of the re&actory bricks.
In addition, Patent Document 2 describes installment of a cooling member near a tuyere in,order to actively derive scaffolding being generated on the stave surface.
According to these techniques, since no refractory bricks are installed in the stave, an abrupt change in the shape of the inside surface due to wear damage of the refractory bricks, which occurs from the blowing-in of the blast furnace to the operational stabilizing phase, can be avoided. In addition, wear damage of the stave can be suppressed even without the refractive bricks through induction of the scaffolding.
Reference Documents Patent Documents
[0006]
- [Patent Document 1] Japanese Unexamined PatentApplication, First Publication No. 2002-115007
[Patent Document 2] Japanese Unexamined Patent Application, First Publication No. 2005-194567
Summary of the Invention
Problems to be Solved by the Invention
[0007]
However, in Patent Document 1 and 2, it is difficult to maintain the shape of the inside surface formed by the scaffolding layer on the stave surface for a long period of time in a stable manner in the height direction and the circumferential direction of the

5 • blast furnace. In addition, the profile in the blast furnace is changed due to an accretion
and changes in operational conditions while the blast fiimace is in operation.
Particularly, in a case in which the circumferential balance of the inside surface profile in
the circumferential direction of the blast furnace changes, stable operation of the blast
fiimace is hindered, and degradation of the productivity is caused.
Li addition, in a structure of the blast furnace in which the refractive bricks are
not installed in the stave, such as the structure described in Patent Document 1, the stave
or sheet iron shell is abruptly heated from room temperature to a high temperature of
approximately 1500°C to 2000°C at the blowing-in of the blast furnace. Therefore,
there is a possibility of the stave being damaged due to heat shock, that is, a sudden heat
change. Therefore, it is desirable to cover the inside surface of the stave with refractory
bricks when constructing the blast furnace. There is a demand for a blast furnace in
which there is no abrupt change in the inside surface profile at the initial period of
operation after blowing-in, and an appropriate inside surface profile can be maintained
for a long time in a stable manner even ui a case in which the refractive bricks are -- -
mstalled.
[0008]
An object of the present invention is to provide a blast furnace bosh zone strucliire in which an inside surface profile of the operational stabilizing phase can be formed after refractory bricks are lost due to thermal shock or wear damage and a method of designing the same.
Methods for Solving the Problem [0009] The present invention realizes a blast furnace in which change in the inside

6
surface shape is small throughout the campaign life of the blast flimace, and stable
operation for a long time and operating life improvement are possible. That is, in the invention, the thickness of refractory bricks disposed on the inside surface of a stave is made to be small, and the stave outside the refractory bricks is disposed at an appropriate position in constructing the blast furnace. Thereby, after the refractory bricks are lost in the initial operational phase of the blast furnace after blowing-in, a scaffolding layer is rapidly generated on the stave surface, aiid the change in the inside surface profile due to wear damage of the refractory bricks in the furnace becomes small in switching from the initial operational phase of the blast furnace to an operational stabilizing phase, and therefore it becomes possible to maintain stable operation of the blast fumace for a long time.
[0010]
The present invention employed the following in order to solve the above
problems and achieve the relevant object.
That is, - ; , — . ,^. . _
(1) A blast fumace bosh zone stnlctvire according to an aspect of the present invention is a structure of a tubular bosh zone that is provided between a tuyere portion and a belly portion of the blast fumace and has a diameter expanding upward along a vertical direction, in which the bosh zone has a ring-shaped sheet iron shell, a bosh zone stave made of copper or copper-alloy provided at an inner circumference of the sheet iron shell, and refractory bricks provided at an inner circumference of the bosh zone stave; a thickness of the refractory bricks in a horizontal direction at a top edge position of the bosh zone is 50 mm to 250 mm.; a thickness of the refractory bricks in the horizontal direction at a bottom edge position of the bosh zone is 200 mm to 500 mm; and a narrow angle formed between a surface of the bosh zone stave and a horizontal plane is 75° to

7 ■ 82° in a cross section of the bosh zone including an axial line thereof.
[0011]
According to the blast furnace bosh zone structure described the above (1), since the thickness of the refractory brick in the bosh zone of the blast furnace is made to be smaller than the thickness of the refractory brick disposed in the blast fiimace of the related art, a change in the inside surface profile caused by wear damage and loss of the refractory brick in the bosh zone of the blast frimace in the initial operational phase after the blowing-in can be significantly suppressed. Furthermore, it is possible to reduce the costs for the bricks and shorten the work period for stacking the bricks in the bosh zone when constructing the blast furnace.
That is, in the above embodiment of the present invention, the inside surface profile in the bosh zone of the blast fiimace at the blowing-in is determined by the surfaces of the refractory bricks disposed on the inside surface of the stave. In the initial operational phase of the blast fiimace after the blowing-in, a majority of the refractory bricks are lost due lo thermal shock or wear damage. However, after the . majority of the refractory bricks are lost, a scaffolding layer generated and grown on the stave surface forms an inside surface profile that is similar to that at the blowing-in (at design), and fransition to the operational stabilizing phase of the blast fiimace is possible. Particularly, the mside surface in the bosh zone of the blast fiimace is an area that comes into contact with the root portion of a cohesive zone (an area in which ores in the accretion begin to be softened and melted, the ores in a semi-molten state are mutually fiised, and connected into a sheet shape) of the accretion falling in the fiimace. After loss of the refractory bricks, the accretion including the ores in a semi-molten state is cooled and fixed on the surface of the stave main body, and therefore a scaffolding layer generated on the inside surface of the stave main body is generated and grown.

~ 8 [00.12]
In the above embodiment of the present invention, the bosh zone stave disposed in the bosh zone of the blast furnace is constituted by a copper or copper-alloy stave main body.
Here, since the thermal conductivity and heat removal capacity of copper or a copper alloy are high, use of the copper or copper alloy stave main body can rapidly cool the accretion including the ores in a semf-molten state on the surface of the stave main body. Thereby, the scaffolding layer can be rapidly generated and grown on the inside surface of the stave in the blast furnace side after the loss of the refractory brick. Furthermore, it is possible to regenerate the scaffolding layer at a rapid pace even when the scaffolding layer is lost by changes in the accretion and operational conditions of the blast fumace.
[0013]
In the above embodiment of the present invention, the thickness of the refractory brick in the horizontal direction at the top edge position of the bosh zone is 50 mm to.25-0 .. . mm, and the thickness of the'jefiractory brick in the horizontal direction at the bottom edge position of the bosh zone is 200 mm to 500 mm.
That is, in this configuration, the thickness of the refractory brick at the bosh zone in the blast fumace is thin compared v^th the related art. As a result, changes in the inside surface profile at the bosh zone in the blast fumace before loss of the refractory brick and the inside surface profile at the bosh zone in the blast fumace after loss of the refractory brick in the fumace height direction and the fumace circumferential direction can be reduced.
Particularly, in a large-scale blast fumace having a blast fumace capacity of 4000 m^ or more, there are cases in which the wear damage state of the refractory brick

9 in the furnace circumferential direction is significantly varied from the initial operational
phase after the blowing-in to the operational stabilizing phase. In the past, there were
problems in that the significant variation deteriorates the circumferential balance of the
inside surface profile, makes blast furnace operation unstable, and degrades the
productivity.
According to the above embodiment of the present invention, the above
problems of the large-scale blast furnace are solved, and a change in the inside surface
profile can decrease considerably from the initial operational phase of the blast furnace
after the blowing-in to the operational stabilizing phase. Thereby, unlike in the related
art, it is not necessary to adjust operational conditions and accretion distribution several
times depending on the change in the inside surface profile in the initial operational
phase after the blowing-in of the blast furnace. Alternately, the frequency of adjusting
the operational conditions or accretion distribution becomes extremely small compared
with in the related art, and it becomes possible to stabilize blast ftimace operation at a
high level for a long time. • ". . .. . . , ., .
Furthermore, according to the above embodiment of the present invention, since the volume and amount of the refractory brick at the bosh zone in the blast furnace can be reduced compared with in the related art, costs for purchasing and accumulating refractory bricks when repairing the blast furnace can be reduced, and, furthermore, the work period for repairing the blast furnace can also be shortened.
[0014]
As described above, the inside surface profile in the operational stabilizing phase of the blast furnace is formed by a scaffolding layer generated on the inside surface of the stave after loss of the refractory brick. As a result of investigations by the present inventors, it was found that, since the accretion including ores in a semi-molten state is

10 ■ rapidly cooled on the surface of the stave main body in the bosh zone in the operational
stabilizing phase of the blast furnace, an inclination angle of the scaffolding layer
generated on the inside surface of the stave with respect to the horizontal plane in the
inside surface profile becomes approximately 75°.
In the above embodiment of the present invention, the bosh zone stave in the blast furnace is disposed so that a narrow angle formed between the surface of the bosh zone stave and the horizontal plane in a cross section of the bosh zone including the axial line thereof becomes 75° to 82°, and more preferably 75° to 78°.
This configuration can make the inclination angle of the scaffolding layer naturally generated on the inside surface of the stave after loss of the refractory brick close to the inclination angle in the operational stabilizing phase of the blast furnace (approximately 75°) in the initial operational phase after the blowing-in of the blast furnace. Thereby, an abrupt change in the inside surface profile generated from the initial operational phase after the blowing-in of the blast furnace to the operational stabilizing phase can be suppressed, and therefore it is possible to prevent the operation from becoming unstable and-the productivity from degrading.
[0015] ^ (2) In the blast fumace bosh zone structure described the above (1), a dimension in the-vertical direction from a center of a tuyere provided at the tuyere portion to the bottom edge position of the bosh zone may desirably be 1200 mm to 1350 mm; and a dimension in the horizontal direction from a front end of the tuyere to the bottom edge position of the bosh zone may desirably be 700 mm to 1100 mm.
Compared with the blast flimace bosh zone structure of the related art, the bosh zone stave composed of a stave main body made of copper or a copper alloy having high thermal conductivity and high heat removal (cooling) capacity is disposed at a position so

11
. that the bott9m end thereof in the blast furnace becomes close to the raceway at the front end of the tuyere, which is at a high temperature. Thereby, a stable scaffolding layer, which is thin and is not easily separated, is generated on the surface of the bosh zone stave in the blast furnace, and a more stable inside profile can be maintained in operating the blast furnace. The protecting effect of the scaffolding layer can decrease the damage rate of the stave and extend the operating life of the bosh zone in the blast furnace. The raceway described above'is a highly porous space in which a high-speed gas is blown in from the tuyere, and the coke in front of the tuyere is fluidized.
According to the above embodiment of the present invention, a stable scaffolding layer that is thin and is not easily separated is generated on the inside surface of the bosh zone stave from the initial operational phase after the bio wing-in of the blast fiamace to the operational stabilizing phase, the change in the inside surface profiles in the furnace height direction and the furnace circumferential direction in the bosh zone becomes small even in a case in which the accretion, operational conditions, and the like
jof.the.blast furnace are changed. Particularly^ it is possible to prevent the operation .
from becoming unstable and-the productivity from degrading which are caused by deterioration of the circumferential balance in the inside surface profile, which is a problem of a large-scale blast furnace, and the blast furnace can be stably operated for a long time.
[0016]
(3) In the blast furnace bosh zone structure described the above (1), a dimension in the vertical direction from the center of the tuyere provided at the tuyere portion to the top edge position of the bosh zone may desirably be 4500 mm to 5500 mm.
Here, the inside surface in the bosh zone of the blast furnace plays roles of supporting the root portion of the cohesive zone of the accretion falling in the -furnace

12 - and maintaining stable operation of the blast furnace.
Here, when the height of the top edge position of the bosh zone stave is set in the above range, the bosh zone stave is disposed above the tuyere portion at an appropriate inclination angle (the narrow angle formed between the surface of the bosh zone stave described above and the horizontal plane), and the dimension in the vertical direction firom the center of the tuyere to the top edge position of the bosh zone is sufficiently extended even in a case in wHich the height position of the root portion of the cohesive zone of the accretion is changed by the change in the operational state of the blast furnace, whereby the root portion of the cohesive zone can be stably supported.
[0017]
In the blast furnace bosh zone structure according to the above embodiment of the present invention, the bosh zone stave desirably has protrusion portions that protrude toward the inside of the furnace from the inside sxxrface, which is the standard surface, and continue in the furnace circumferential direction.
In this configuration j the protrusion portions, that-protrude toward the inside, of- . ■
the furnace from the inside surface, which is the standard surface, decelerates the falling speed of the accretion (including iron ores in a semi-molten state) near the root portion of the cohesive zone falling in the blast fiimace. Thereby, a scaffolding layer on the standard surface can be generated and grown at a rapid pace even when the scaffolding layer on the standard surface is separated and dropped by a change and the like in the operational state of the blast furnace. That is, since an appropriate inside surface profile can be formed by the generation and growth of the scaffolding layer, it is possible to stably maintain operation in the furnace for a long time.
In addition, since the scaffolding layer generated and grown along the standard surface of the stave main body coats the stave main body (the self-lining effect), the stave

13 ■ main body is not directly exposed to the high-temperature cohesive zone, and it is
possible to increase the heat resistance as the bosh zone and the belly portion stave.
[0018]
Particularly, in the above embodiment of the present invention, since a stave main body made of copper or an copper alloy having high thermal conductivity and high heat removal capacity is used, the accretion including the iron ores in a semi-molten state, which falls in the blast furnace, is decele'rated by the protrusion portions on the standard surface, and then abruptly cooled so as to be attached to the standard surface. Thereby, a layer coated with the scaffolding can be regenerated at a rapid pace even when the scaffolding layer on the standard surface is separated and dropped by a change and the like in the operational state of the blast furnace.
In addition, the protrusion portions continuously provided along the entire circumference in the furnace circumferential direction with respect to the bosh zone stave facilitate maintaining of the favorable circumferential balance of the inside surface profile in the operation of a l^rgcrscale blast furnace, and the,blast~fumace can be stably operated at a high level for a-long time.
[0019]
In the bosh zone stave, it is desirable to form a cooling pipeline even in the protrusion portions in addition to the cooling pipeline formed' in the stave main body.
In the above embodiment of the present invention, since the stave main body is made of copper or a copper alloy having high thermal conductivity and high heat removal capacity, the protrusion portions are sufficiently cooled only with the cooling pipeline in the stave main body; however, when a cooling pipeline is formed in the protrusion portions, and the protrusions are directly cooled, the temperature of the surface thereof is decreased so that it is possible to further promote generation of a

14 scaffolding.
[0020]
(4) A blast fomace design method according to an aspect of the present invention is a design method of a blast furnace having a tuyere portion, a furnace trunk portion, and a tubular bosh zone which is provided between the tuyere portion and the furnace trunk portion, and has a diameter expanding upward along a vertical direction, in which the bosh zone has a ring-shaped sheet iron sliell, a bosh zone stave made of copper or copper-alloy provided at an inner circumference of a sheet iron shell, and refractory bricks provided at an inner circumference of the bosh zone stave, in which a thickness of the refractory bricks in a horizontal direction at a top edge position of the bosh zone is set to 50 mm to 250 mm; a thickness of the refractory bricks in the horizontal direction at a bottom edge position of the bosh zone is set to 200 mm to 500 mm; and a narrow angle formed between a surface of the bosh zone stave and a horizontal plane is set to 75° to 82° in a cross section of the bosh zone including an axial line thereof
... ^ According to the blast furnace, designing method, the same actions andeffects as.
in the blast furnace bosh zone structure according to the above aspect of the present invention can be obtained.
Brief ;Description of the Drawings
[0021]
FIG. 1 is a schematic view showing a blast flimace according to an embodiment of the present invention.
FIG 2 is a cross-sectional view showing the installation state and the initial inside surface profiles of the bosh zone stave and the refractory brick in the blast furnace bosh zone structure of the same blast furnace in blowing-in (at design).

15 FIG. 3 is a cross-sectional view showing the inside surface profile at the
bio wing-in (at design), initial operational phase, and operational stabilizing phase of the
blast furnace bosh zone structure of the same blast furnace.
FIG 4 is a graph showing changes in the operated period and the production volume in the blast furnace bosh zone structure of the related art.
FIG. 5 is a schematic view showing a state of the bosh zone refractory brick at the bio wing-in (at design) of the blast fiujiace bosh zone structure of the related art.
FIG 6 is a schematic view showing a state of the bosh zone refractory brick in the process of wear damage in the initial operational phase of the blast furnace bosh zone structure of the related art.
FIG 7 is a schematic view showing a state of the bosh zone refractory brick lost in the operational stabilizing phase of the blast furnace bosh zone structure of the related art.
FIG 8 is a graph showdng changes in the operated period and the production volume iruthe blast furnace bOsh zone structure of the embodiment.
■ FIG 9 is a schematic view shovmig an initial operational state of the bosh zone refractory brick at the bio wing-in (at.design) of the same blast furnace bosh zone structure.
" FIG 10 is a schematic view showmg a state of the bosh zone refractory brick in the process of wear damage in the initial operational phase of the same blast furnace bosh zone structure.
FIG 11 is a schematic view showing a state of the bosh zone refractory brick lost in the operational stabilizing phase of the same blast furnace bosh zone structure.
Embodiments of the Invention

16
: [0022]
Hereinafter, embodiments of the blast furnace bosh zone structure and the method of designing the same in the present invention will be described based on the accompanying drawings.
In FIG. 1, a blast furnace 1 has a tubular furnace body 2 that is constructed on a foundational ground.
The furnace body 2 is divided into a furnace opening portion SI, a shaft portion S2, a belly portion S3, a bosh zone S4, a tuyere portion S5, and a furnace bottom portion S6 sequentially from a gas collecting mantel 3 on the top. Generally, the inner diameter of the shaft portion S2 extends toward the bottom, the iimer diameter of the belly portion S3 forms the largest diameter, and the inner diameter of the bosh zone S4 contracts toward the bottom. The bosh zone S4 is tubular, provided between the tuyere portion S5 and the belly portion S6, and has a diameter extendmg toward the top in the vertical direction.
[0023]
Generally, the furnace body 2 has a charging apparatus installed at the gas collecting mantel 3, and a granular accretion 4 is charged into the fumace from the charging apparatus. As the accretion 4, an ore-based accretion having a particle size of approximately 8 mm to 25 mm and a coke-based accretion having a particle size of approximately 20 mm to 55 mm are alternately charged into a lamellar shape. As a result, a massive zone 4A in which an iron ore and coke alternately form layers is formed between the fumace opening portion SI and the shaft portion S2 in the fumace.
In the fumace body 2, the tuyere portion 5 is installed on the top of the fumace bottom portion S6, and hot air 5 A is blown in fi'om the tuyere portion. The coke in the massive zone 4A is combusted and becomes hotter due to the hot air 5A, and a raceway

17 5B (a highly porous space in which a high-speed gas is blown in from the tuyere 5, and
the coke before the tuyere 5 is fluidized) is formed by the high-temperature gas in the
vicinity of the tuyere 5. The hot air in the raceway 5B melts the iron ore in the massive
zone 4A.
[0024]
The combustion of the coke and the melting of the iron ore proceeds sequentially at the bottom portion of the'inassive zone 4A, and a substantially conical cohesive zone 4B is formed in the furnace from the bosh zone S4 toward the bottom of the shaft portion S2.
Iron ,6A melted at the cohesive zone 4B passes through a dripping zone 4C, drops toward the furnace bottom portion S6, and piles in the furnace bottom portion S6 as hot metal 6B. Coke and the like, which are not completely combusted in the cohesive zone 4B, pass through the dripping zone 4C, fall and accumulate on the furnace bottom portion S6, and form a conical fiimace core 4D on the hot metal 6B.
The fiimace body 2.iias.a taphole.d-installed at tbe furnace.bottom portion S6> and the hot metal 6B piled in the fiimace bottom portion S 6 by the taphole 6 is discharged outside the blast fiimace 1.
[0025] : The fiimace body 2 has a sheet iron shell 2A at the outermost circumference, and a cooling stave or a refractory brick 2D attached to the inside of the sheet iron shell 2 A.
A shaft stave 2B is attached to an area S7 facing the massive zone 4A from the top to the middle ofthe shaft portion S2. In the area S7, since the granular accretion 4 included in the massive zone 4 A comes into contact with the surface ofthe stave 2B and sequentially falls, there are cases in which mechanical abrasion occurs on the surface of the stave 2B.

18 A bosh zone stave 2C is attached from the bottom of the shaft portion S2 to an
area S8 including the belly portion S3 and the bosh zone S4. In the area S8, since the
root portion 4E of the cohesive zone 4B composed of the high-temperature accretion 4
(an area in which ores in the accretion 4 begin to be softened and melted, the ores in a
semi-molten state are mutually fused, and coimected into a sheet shape) comes into
contact with the area and sequentially falls, there are cases in which high
temperature-induced abrasion occurs on'the surface of the stave 2C inside the blast
furnace 1.
The refractory brick 2D is attached to the inside surface of the staves 2B and 2C according to necessity. In addition, a refractory brick 2E is thickly accumulated on the fumace bottom portion S6 in which the high-temperature hot metal 6B is retained.
[0026]
In the present embodiment, as shown in FIG 2, a blast furnace bosh zone structure 9 is employed in an area extending from the bottom of the belly S3 to the tuyere :, -5 in the tuyere portion S5 which is dominated by the-bosh zone S4.
The bosh zone S4 in the blast fumace bosh zone structure 9 has a ring-shaped sheet iron shell 2A disposed outside, a copper or copper-alloy bosh zone stave 10 provided at the inner circumference of the sheet iron shell 2 A, and a refractory brick 20 (2D) provided at the iimer circumference of the bosh zone stave 10. The bosh zone stave 10 may be a casting obtained by casting copper or a copper alloy by batch. In addition, the stave 2C has a thin plate-shaped stave main body 11 that is cut out from a copper or copper alloy plate material.
Plural arrays of protrusion portions 12 which continue horizontally are formed on the surface side of the stave main body 11, and recess portions 13B which are hollowed toward the outside of the blast fiimace 1 are formed therebetween. A surface

19
; of the recess portion 13B, which is lower than the protrusion portion 12, is a planar
surface (standard surface) 13.
[0027]
The bosh zone stave lOA (10) disposed on the top end side of the bosh zone S4 is disposed from the bosh zone S4 through the belly portion S3. The bosh zone stave lOA is inclined with respect to the axial line 0 of the bosh zone S4 only at a portion located at the bosh zone S4.' Specifical'ty, the inclination angle (narrow angle) d formed between the planar surface (standard surface) 13 of the bosh zone stave 10 and the horizontal plane in a cross section of the bosh zone S4 which includes the axial line 0 is 75° to 82°, and preferably 75° to 78°. In addition, the bosh zone stave 10 disposed on the tuyere portion S5 side of the bosh zone stave lOA is also, similarly, inclined with respect to the axial line 0.
The thickness Lu of the refractory brick 20 (2D) in the horizontal direction at the top edge position Ey of the bosh zone S4 is 50 mm to 250 mm, and preferably
approximately 50 mm to 100-mm. In addition, the.thicknesaLL-of the refractory brick
20 (2D) in the horizontal direction at the bottom edge position EL of the bosh zone S4 is 200 mm to 500 mm, and preferably approximately 200 mm to 300 mm.
[0028] - The recess portion 13B including the planar surface 13, which is the standard surface, is formed by cutting from the surface of the stave main body 11, and the protrusion portion 12 is formed by not being cut during the cutting. Here, the planar svirface 13 is considered as the standard surface of the bosh zone stave 10, and the protrusion portion 12 protrudes from the standard surface of the bosh zone stave 10.
The protrusion portions 12 are mutually connected with each other in a case in which the bosh zone stave 10 is attached in the fiamace, and the respective protrusions 12

20 form a perfect ring shape in the blast furnace 1.
The front end surface of the protrusion portion 12 may be coated with a TiN, TiC, WC, Ti-Al-N-based, or other high-hardness material.
The elution amount of the protrusion portion 12 from the planar surface 13, which is the standard surface, is 50 mm to 150 mm (an elution amount approximately one to three times the maximum particle diameter of a coke-based accretion having a large average particle diameter, which is'i55 mm), and the interval between the adjacent protrusion portions 12 is approximately 500 mm to 1000 mm, and more preferably 500 mm to 700 mm.
[0029]
Particularly, since the adjacent protrusion portions 12 lower the falling speed of the accretion at the planar surface 13, which is the standard surface of the stave main body 11, so as to increase the cooling efficiency of the accretion and promote formation of a scaffolding layer, the interval between the adjacent protrusion portions 12 becomes - important.
When the interval between the adjacent protrusion portions 12 is larger than 1000 mm, the falling speed of the accretion including the iron ore in a semi-molten state, which falls, particularly, in the vicinity of the protrusion portions 12 on the high location side, is reduced, and the action of generating the scaffolding layer on the planar surface 13, which is the standard surface, by cooling decreases.
When the interval of fhe adjacent protrusion portions 12 is smaller than 500 mm, the falling speed of the accretion including the iron ore in a semi-molten state, which falls between the adjacent protrusion portions 12, is reduced, and the thickness of the scaffolding layer generated on the planar surface 13, which is the standard surface, by cooling becomes excessively thick. When the scaffolding layer is generated to be

21 excessively thick, the inside surface profiles on the bosh zone and the belly portion are
significantly changed in a case in which the scaffolding layer is separated due to changes
or the like in the operational conditions of the blast furnace 1, which is not preferable in
terms of maintaining of the stable operation of the blast furnace 1.
[0030]
As shown in FIG. 2, a refractory 13A is attached to the insides of the recess
i
portions 13B (between the adjacent protmsion portions 12) along the planar surface 13, which is the standard surface. Separately from the refractory 13 A, the refractory brick 20 is attached along the refractory 13 A and the front end surfaces of the protrusion portions 12.
In the blast furnace bosh zone structure 9 of the present embodiment, the refractory brick 2D inside the stave 2C described above is constituted by the refractory brick 20 (refer to FIG. 1).
As described above and shown in FIG. 2, the thickness of the refractory brick 2D, .. that is, ..the thickness Lu of the refractory brick 20 in the horizontal direction at the top edge position Eu of the bosLzone stave 10 is 50 mm to 250 mm, and the thickness LL of the refractory brick 20 in the horizontal direction at the bottom edge position EL is 200 mm to 500 mm. - [0031]
The refractory brick 20 and the refractory 13 A protect the bosh zone stave 10 from thermal shock when the blast furnace 1 is blown-in (in a state in which a scaffolding coat is not yet formed).
At the initial operational phase of the blast furnace 1 after the blowing-in, the refractory brick 20 and the refractory 13A are sequentially wear-damaged by high heat and a friction force, which come from the root portion 4E of the cohesive zone 4B of the

22 .' accretion 4 in a high-temperature state as shown in FIG. 1. At this time, as shown in
FIG. 3, the inside profile PI in the bosh zone portion S4 is constituted by the surface of
the wear-damaged refractory brick 20.
[0032]
However, in the furnace, a scaffolding 7 layer derived from the accretion 4 is grown by operation of the blast furnace 1 with respect to loss of the refractory brick 20 due to the wear damage, and the inside surface of the bosh zone stave 10 is coated with the scaffolding 7 layer (the inside profile P2).
After the majority of refractory brick 20 is lost at the initial operational phase of the blast furnace 1 after blowing-in, the scaffolding 7 layer of the accretion 4 is generated and grown on the standard surface 13 of the stave main body 11, or the surface of the refractory 13 A, and the scaffolding 7 is formed at a thin thickness after passage of 4 years from the blowing-in. In addition, the refractory 13 A and the protrusion portions 12 m the bosh zone portion S4 are further coated with the scaffolding 7 layer (the inside profile,P.3-). -
Furthermore, after passage of 4 to 10 years from the blowing-in, the scaffolding 7 layer is further grown on the standard surface 13 of the stave maui body 11, or the scaffolding 7 layer formed in the inside profile P3, and the profile becomes closer to the inside surface profile PO of the refractory brick 20 in the bosh zone S4 at the blowing-in due to an increase in the thickness of the scaffolding 7 layer. In addition, the scaffolding 7 layer and the refractory 13A on the planar surface 13, which is the standard surface, are separated by changes in the operational state of the blast furnace 1, and, after that, the planar surface 13 or the protrusion portions 12 are coated by the rapid growth of the scaffolding 7 layer even when the planar surface 13 A is exposed. Thereby, the inside surface of the blast furnace 1 in the bosh zone stave 10 is automatically flattened

23 ' by the scaffolding 7 layer into a flat surface.
[0033]
Returning to FIG 2, a cooling pipeline (not shown) is formed in the stave main body 11, and a cooling pipe 16 is connected to the rear surface side of the stave main body 11. _
Cooling water from the cooling pipe 16 passes through the cooling pipeline in the stave main body 11, the planar surfaae 13, which is the standard surface of the bosh zone stave 10, and the protrusion portions 12 are cooled by adjustment of the flux of the cooling water, and are adjusted to an appropriate temperature respectively.
Such appropriate cooling promotes growth of the scaffolding 7 layer (refer to FIG. 3) of the accretion 4, and the thickness and the like of the scaffolding 7 layer on the surface of the bosh zone stave 10 in the blast furnace 1 can be adjusted to an appropriate coating state.
[0034]
As described above, in the blast furnace bosh zone structure 9 of the present embodiment, an initial surface shape (initial profile) is formed on the inside surface of the refiractory brick 20 in the blast furnace 1 from the bio wing-in (at design) to the initial operational phase of the blast furnace, and the inside surface profile of the operational stabilizitig phase is formed on the inside surface of the blast surface 1 by the scaffolding 7 layer generated on the surface of the stave main body 11 after the refractory brick 20 is lost by wear damage.
In the blast furnace bosh zone structure of the related art, in the initial operational phase which extends 2 to 4 years from the blowing-in, the inside surface profile in the bosh zone was significantly changed, which caused operation of the blast furnace to be unstable and the productivity to degrade.

24 According to the present embodiment, since the thickness of the refractory brick
20 in the bosh zone S4 is made to be thin, and the bosh zone stave 10 is inclined at an
appropriate angle so that the scaffolding 7 layer is rapidly formed on the standard surface
of the stave main body 11 after the loss of the refractory brick 20, a change in the inside
surface profile in the initial operational phase after the blowing-in is small compared with
the inside surface profile at the blowing-in (at design), and therefore the operational
stability and productivity of the blast furfiaee can be maintained successfully.
[0035]
In the blast furnace bosh zone structure 9 of the present embodiment, the bosh zone stave 10 is specifically disposed with respect to the tuyere 5.
That is, in the blast furnace bosh zone structure 9, the bosh zone stave 10 disposed in the area of the bosh zone S4 is installed so that the inclination angle a formed between the standard surface 13 of the bosh zone stave 10 and the horizontal plane in a cross section of the bosh zone S4 including the axial line thereof is 75° to 82°, and preferably 75° to 78°.-.
[0036]
The dimension HI in the vertical direction from the center HO of the tuyere 5 provided in the tuyere portion S5 to the bottom edge position (the bottom end position of the inside surface of the blast furnace 1 of the bosh zone stave 10, which is installed at the lowest step of the blast flimace bosh zone structure 9) EL of the bosh zone S4 is 1200 mm to 1350 mm, and the dimension Dl in the horizontal direction from the front end DO of the tuyere 5 to the bottom edge position EL of the bosh zone S4 is 700 mm to 1100 mm (refer to FIG. 2). Meanwhile, the center height HO of the tuyere 5 indicates the height at the turning center position of the tuyere in a case in which the nozzle in the tuyere 5 is a turning type.

25 AcQording to the present embodiment, compared with the blast furnace bosh
zone structure of the related art, the bosh zone stave 10 composed of the stave main body
11 made of copper or a copper alloy which has high thermal conductivity and high heat
removal capacity is disposed at a position so that the bottom edge position EL in the blast
furnace 1 comes close to the raceway 5B (a highly porous space in which a high-speed
gas is blown in from the tuyere, and the coke in front of the tuyere is fluidized) at the
tuyere front, which is at a high temperatiire. Thereby, a stable scaffolding layer, which
is thin and is not easily dropped, is generated on the surface of the bosh zone stave 10 in
the blast furnace 1 at a rapid pace, and it is possible to maintain a more stable inside
profile during operation of the blast furnace. Furthermore, since the wear damage rate
of the stave can be decreased by the protection effect, the operational life of the blast
furnace bosh zone structure can be extended.
Since a stable scaffolding layer, which is thin and is not easily dropped, is generated on the inside surface of the bosh zone stave 10 from the initial operational . phase, of the-J^last furnace 1 after the blowing-in-to the operational stabilizing phase,-the. change in the inside surface profiles of the bosh zone S4 in the fiamace height direction and the furnace circumferential direction become small compared with the inside surface profile at the bio wing-in (at design) in spite of the changes in the accretion, operational conditions, and the like of the blast furnace 1. As a result, it is possible to prevent the operation from becoming unstable and the productivity from degrading, which are caused by deterioration of the circumferential balance in the inside surface profile, which is a problem particularly in a large-scale blast furnace, and the blast furnace 1 can be stably operated for a long time.
[0037]
Furthermore, the dimension H2 in the vertical direction from the center HO of

26 the tuyere provided in the tuyere portion S5 to the top edge position (the top end position
of the surface of the bosh zone stave 10 in the blast furnace 1, which is installed at the
lowest step of the blast furnace bosh zone structure 9 described above) Eu of the bosh
zone S4 is 4500 mm to 5500 mm.
The inside surface in the bosh zone S4 of the blast furnace 1 plays roles of supporting the root portion 4E of the cohesive zone 4B of the accretion 4 failing in the blast furnace 1, and maintaining the stabl'e operation of the blast furnace 1. Thereby, when the height of the top edge position Eu of the bosh zone stave 10 is set in the above range, the bosh zone stave 10 is disposed above the tuyere 5 at an appropriate bosh zone angle (inclination angle), and the dimension H2 is sufficiently extended even in a case in which the height position of the root portion 4E of the cohesive zone 4B of the accretion 4 is changed by the change in the operational state of the blast furnace 1, whereby the root portion 4E of the cohesive zone 4B can be stably supported.
[0038] ,. In-the present embodiment as described above, aflerthe blowing-ui of theblast. furnace, the refractory brick 20 is wear-damaged as the blast fumace is operated, the inside surface profiles in the fumace height direction and the fumace circumferential direction are maintained in an appropriate state by generation of the scaffolding 7 layer on the inside surface in the bosh zone stave 10, and degradation of the operational achievement of the blast fumace 1 due to the secular change of the inside surface profile can be suppressed to the minimum extent.
Hereinafter, the secular change of the inside surface profile m the blast fumace bosh zone structure 9 of the present embodiment and the secular change in the blast fumace bosh zone stmcture of the related art to which the present embodiment is not applied will be compared using a computer simulation.

27 [0039]
FIG. 4 shows a change in the production volume over the passage of the
operated period in the blast furnace bosh zone structure of the related art to which the
present embodiment is not applied. FIGS. 5, 6, and 7 schematically show the wear
damage states of the bosh zone refractory brick 20 at the blowing-in (at design), initial
operational phase, and operational stabilizing phase of the same blast furnace bosh zone
structure. ' ']
FIG 8 shows a change in the production volume over the passage of the operated period in the blast furnace bosh zone structure 9 to which the present embodiment is applied. FIGS. 9,10, and 11 schematically show the wear damage states of the refractory brick 20 in the bosh zone S4 at the blowing-in (at design), initial operational phase, and operational stabilizing phase of the same blast furnace bosh zone structure 9.
[0040]
In the blast fomace l .of .the related art for which_the. change-in. the production.-volume is shown in FIG 4, the basic structure of the bosh zone S4 is the same as in the embodiment of the present invention as shown in FIGS. 1 and 2 described above, but the thickness (the thickness of the bosh zone stave 10 in the horizontal direction at the bottom edge position EL) of the refractory brick 20 disposed on the inside surface side of the bosh zone stave 10 is larger than 500 mm, the top edge position Eu is larger than 250 mm, the dimension H2 is smaller than 4000 mm, and the inclination angle a is larger than 82°.
[0041]
In FIG 4, 6 months from the blowing-in of the blast fiimace 1 (0 year in the operated period) composes a "blowing-in and launching phase Tl." In this phase, the

28 '. accretion, operational conditions, and the like of the blast furnace 1 are adjusted, and the
production volume is increased up to the target production level LO.
6 months to 2 years in the operated period composes an "initial operation after blowing-in phase T2." hi this phase, in the bosh zone S4, the refractory brick 20 attached to the inside of the bosh zone stave 10 is maintained with extremely little wear damage, the inside surface profile and the circumferential balance in the initial phase are favorably maintained by the surface of the refractory brick 20 (refer to FIG. 5). Therefore, the actual production volume is also maintained at the target production level LO, and stable operation is continued (refer to the period T2 in FIG. 4).
[0042]
The two to four years in the operated period composes a "bosh brick damage and separation phase T3." In this phase, in the bosh zone S4, most of the refractory brick 20 is damaged, and sequentially dropped on a part to part basis such that the inside surface profile is deteriorated, and the circumferential balance in the bosh zone S4 is - deteriorated (refer to FIG. 6).- Particularly,..damage or separation-olthe refractory brick 20 begins from a specific location in the bosh zone S4 in the furnace circumferential direction, and sequentially expands throughout the entire circumference. Therefore, the inside surface profile is deteriorated, blast furnace operation is significantly affected by the irregularity of the circumferential balance so as to becomes unstable until the entire circumference is dropped, and a state in which the production volume is widely lowered continues (refer to T3 phase in FIG. 4).
In this period, a variety of blast furnace operations are adjusted so that a scaffolding layer is generated to the inside of the bosh zone S4 in the blast furnace, the inside surface profile in the furnace circumferential direction is flattened, and the circumference balance is restored, whereby the operation becomes stabilized, and the

29 production volume is also recovered.
[0043]
4 years to 10 years in the operated period composes an "operational stabilizing phase T4." In this phase, in the bosh zone S4, the refractory brick 20 is completely lost, the inside surface is formed by the surface of the bosh zone stave 10 or the scaffolding layer (refer to FIG. 7). At a point in time at which blast flimace operational conditions and accretion distribution are optimized;;an appropriate thickness of a scaffolding 7 layer is generated on the surface of the bosh zone stave 10. This scaffolding 7 layer forms a flat inside surface profile on the inside surface, and the circumferential balance throughout the entire circumference in the furnace circumferential direction also becomes favorable. Therefore, compared with the bosh brick damage and separation phase T3, blast furnace operation becomes stable, and the production volume is also recovered. The production volume LI in this phase shows gradually a tendency of straight line from top left to bottom right due to aging degradation at each portion of the blast furnace (refer to the period T4 in FIG. 4).
However, in the blast furnace bosh zone structure of the related art, in an intermediate operational stabilizing phase T4, in a case in which the quality of raw materials and fuels is changed, or operational conditions are changed, the scaffolding 7 layer-on the inside surface in the bosh zone stave 10 is sporadically separated and dropped. There are problems in that the dropping causes an abrupt and temporary change in the inside sxirface profile, deteriorates the circumference balance, and causes a temporary and significant change in the production volume.
[0044]
10 years to 14 years in the operated period composes an "unstable operational phase T5."- In this period, in the bosh zone S4, wear damage of the bosh zone stave 10

30 proceeds, the influence of the change in the quality of materials and fuels (deterioration
of the coke quality, change in the sintering quality, and the like) becomes significant, and
the changes of loss and regeneration of the scaffolding on the inside surface in the bosh
zone stave 10 become significant. Accordingly, the change in the inside surface profile
or the change in the circumferential balance becomes larger, and the status in the blast
furnace 1 is significantly changed compared with in the operational stabilizing phase T4
described above. Thereby,'since aging'degradation at the respective portions in the blast
furnace 1 further proceeds, consequently, the production volume is lowered, and the
change is also increased. The production volume L2 in this phase shows significantly a
tendency of straight line from top left to bottom right (refer to the period T5 in FIG. 4).
[0045]
After 14 years in the operated period, due to damage of the stave at high-temperature load portions in the bosh zone S4 or the shaft portion S2 or proceeding of wear damage of the hearth wall brick, full production at the maximum thrust of the blast furnace .1-becomes difficult, timely and sudden,rest of wind, long-time rest of wind . for repair, and the like become necessary. Thereby, operational conditions are frequently changed, and it becomes impossible to stably maintain the scaffolding 7 in the bosh zone S4 due to the change in pre-tuyere conditions. In such a status, consequently, the production volume is significantly reduced, the operational conditions are not gradually stabilized due to aging degradation, aging, and the like of a variety of facilities, the furnace enters into a phase in which the bosh zone profile becomes most unstable due to the change in pre-tuyere conditions, and the circumferential balance becomes most unstable, and a furnace terminal phase is reached.
[0046]
The blast furnace 1 as shown in FIG. 8 employs the blast fiimace bosh zone

31 : structure 9 of the present embodiment as shown in FIGS. 1, 2, and 3 described above, the
thickness of the refractory brick 20 attached to the inside surface side of the bosh zone
stave 10 in the horizontal direction is 50 mm to 250 m at the top edge position Eu of the
bosh zone stave 10 disposed at the lowest step, and 200 mm to 500 mm at the bottom
edge position EL of the bosh zone stave 10, and the inclination angle a formed between
the planar surface 13, which is the standard surface, and the horizontal plane is 75° to
82°.
[0047]
In FIG. 8, 6 months from the blowing-in of the blast fiimace 1 (0 year in the operated period) composes a "blowing-in and launching phase Ul." In this phase, the accretion, operational conditions, and the like of the blast furnace are adjusted, and the production volume is increased up to the target production level LO. At this point in time, the inside profile PO (refer to FIG. 3) is formed.
6 months to 2 years in the operated period composes an "initial after launching .. -. phase U2." In this phase, in the bosh zone S4, the xefractory^brick 20.attached to the inside of the bosh zone stave 10 is maintained with exfremely little wear damage, the inside surface profile and the circumferential balance in the initial phase are favorably maintained by the surface of the refractory brick 20 (refer to FIG. 9). Therefore, the actual production volume is also maintained at the target production level LO, and stable operation is continued (refer to the period U2 in FIG. 8, the profile PO in FIG. 3).
[0048]
2 years to 4 years in the operated period composes a "bosh brick damage and separation phase U3." In this phase, in the bosh zone S4, the refractory brick 20 is damaged, and, sometimes, is sequentially dropped on a part to part basis. However, since the thickness of the refractory brick 20 is formed to be thin based oh the present

32 ; embodiment^ compared with the related art, a significant change in the inside surface
profile or a significant change in the circumferential balance in the bosh zone S4 is
suppressed (refer to FIG. 10). Thereby, it is possible to prevent the operation from
becoming unstable and the production volume from significantly degrading, which
occurs in the related art, (the phase T3 in FIG. 4) (refer to the phase U3 in FIG. 8, the
profile PI in FIG. 3).
[0049]
4 years to 10 years in the operated period composes an "operational stabilizing phase U4." In this phase, in the bosh zone S4, the refractory brick 20 is completely lost, the inside surface is formed by the scaffolding 7 layer generated on the surface of the bosh zone stave 10 (refer to FIG. 11). At this time, in the blast furnace bosh zone structure 9 of the present invention, the bosh zone stave 10 is disposed so that the planar surface 13, which is the standard surface of the bosh zone stave 10, forms an appropriate inclination angle a (75° to 82°). Thereby, the scaffolding 7 layer is efficiently generated . . with a thin thickness on the inside svirface in. the bosh zone stave 10 and a uniform. — thickness in the furnace circumferential direction, and therefore a flat inside surface profile is secured, and the circumferential balance throughout the entire circumference in the blast furnace 1 also becomes favorable. Therefore, it is possible to stabilize blast fumace operation, and secure a value close to the target production level LO (refer to the period U4 in FIG. 8, the profiles P2 and P3 in FIG. 3).
[0050]
In addition, the scaffolding 7-layer is generated and grown on the inside surface in the bosh zone stave 10 in a state in which the scaffolding layer is thin and is not easily dropped compared with the related art, and therefore the inside surface profile is not > abruptly and temporarily changed due to sporadic dropping of the scaffolding layer as in

33 . the related art. Furthermore, the circumferential balance does not deteriorate throughout
the entire circumference in the blast furnace 1, and stabilized blast furnace operation can
be maintained. In addition, since the inclination angle of the planar surface 13, which is
the standard surface of the bosh zone stave 10, is appropriate, the scaffolding 7 layer on
the standard surface is efficiently regenerated, and significant degradation of the
production volume is caused unlike in the related art (the phase T4 in FIG. 4) even when
the scaffolding 7 layer is sporadically separated and dropped m a case in which the
operational conditions are changed.
[0051]
10 years to 14 years in the operated period composes an "unstable operational phase U5." In this period, in the bosh zone S4, similarly to the related art (the phase T5 ui FIG. 4), a furnace terminal phase is reached. However, during this phase, the inside surface profile and the circumferential balance can be optimized by the appropriate inclination angle a (75° to 82°) of the planar surface 13, which is the horizontal plane of .thcLboskzone stave 10 described above, anda-valuejclose to the target production level.—--LO can be secured (refer to the period U5 in FIG. 8).
[0052]
Meanwhile, the present invention is not limited to the above embodiment, and uicludes variation and the like within a scope in which the object of the present invention can be achieved.
In the embodiment, the inside surface in the bosh zone stave 10 and the inside surface profile in the operational stabilizing phase, which is formed by the scaffolding 7, have been described in a case in which the inclination angle of the bosh zone stave 10 with respect to the horizontal plane is 75° to 78°, but the same effects can be obtained m a case in which the mclination angle a is 75° to 82°.

34 [0053]
In the embodiment, the bottom edge position EL (refer to FIG. 2) on the inside
surface in the bosh zone stave 10 installed at the lowest step of the blast furnace bosh
zone structure 9 may be provided as long as the dimension HI in the vertical direction
from the center HO of the tuyere 5 to the bottom edge position EL of the bosh zone S4 is
1200 mm to 1350 mm, and the dimension Dl in the horizontal dhection from the front
end DO of the tuyere 5 to the bottom edge position EL of the bosh zone S4 is 700 mm to
1100 mm. For example, in a case in which the boundary between the bosh zone S4 and
the tuyere portion S5 can be set as low as the boundary between the bosh zone S4' and
the tuyere portion S5' (refer to FIG 2), the bottom edge position EL' can be set to be
lower than the bottom edge position EL described above. In this case, the bottom edge
position EL' is set on an extension line of a straight line that connects the original bottom
edge position EL and the top edge position Eu, the dimension HI' from the center HO of
the tuyere 5 to the bottom edge position EL', and the dimension Dl' from the front end
DO of the.tuyere.5.to the.bottom edge position EL' are obtained. . The dimension Hl!-.and.-
the dimension Dl' are also within the numerical range of the dimension HI and the
dimension Dl described above.
[0054]
- In the embodiment, when the bosh zone stave 10 is arrayed in the blast fiimace 1,
the respective protrusion portions^ 12 continue and form a ring shape, but the protrusion
portions may be a mutually discontinuous ring shape, or the protrusion portions may be
arrayed in a zigzag manner with different heights. However, the circumferential
balance is important in terms of the operation of the blast furnace 1, and needs to be
taken into consideration so that symmetry around the center of the blast fiimace 1 can be
obtained.

35 The protrusion portions 12 may be formed on the surface of the bosh zone stave
10 or separate members, which function as the protrusion portions, may be installed on
the inside surface separately from the stave. In addition, in the present embodiment, it
is more preferable to form the protrusion portions 12.
[0055]
In the embodiment, the cooling pipe 16 is formed in the bosh zone stave 10 i including the protrusion portions 12, but the protrusion portions 12 may not be provided.
However, when the temperature of the surfaces of the protrusion portions 12 is decreased,
generation of the scaffolding 7 can be promoted, the protrusion portions can be used for
adjusting the increase and decrease of the scaffolding 7 through temperature control, the
inside surface profile can be stably maintained, and the operational life of the protrusion
portions can be extended.
In addition, disposition of the protrusion portions 12, the cross-sectional shape,
disposition of the cooling pipe 16, the overall shape of the stave 10, the dimensions, and
.. -the like may be appcopriately-selected in carrying out the, invention.
Description of the Reference Symbols
[0056] 1 ...BLASTFURNACE 2... FURNACE BODY 2A... SHEET IRON SHELL 2B,2C... STAVE 2D, 2E ... REFRACTORY BRICK 3 ... GAS COLLECTINGMANEL

36 4... ACCRETION
4A... MASSIVE ZONE
4B... COHESIVE ZONE
4C... DROPPING ZONE
4D... FURNACE CORE
5...TUYERE
5A... HOT AIR
5B... RACEWAY
6...TAPH0LE
6A...IR0N
6B... HOT METAL
7... SCAFFOLDING
9 ... BLAST FURNACE BOSH ZONE STRUCTURE
_ 10 ... BOSH ZONE STAVE _._
11... STAVE MAIN BODY:
12 ... PROTRUSION PORTION
13 ... PLANAR SURFACE WHICH IS STANDARD SURFACE 16....COOLING PIPE
20 ... REFRACTORY BRICK
DO ... TUYERE FRONT END POSITION
Dl ... DIMENSION FROM THE TUYERE FRONT END TO THE BOTTOM EDGE
POSITION OF THE BOSH ZONE
EL ... BOSH ZONE STAVE BOTTOM EDGE'

37 ." Eu... BOSH ZONE STAVE TOP EDGE
HO ... TUYERE CENTER HEIGHT
HI ... DIMENSION FROM THE TUYERE CENTER TO THE BOTTOM EDGE
POSITION OF THE BOSH ZONE
H2 ... DIMENSION FROM THE TUYERE CENTER TO THE TOP EDGE POSITION
OF THE BOSH ZONE
SI... FURNACE OPENING PORTION"
S2... SHAFT PORTION
S3 ...BELLYPORTION
S4... BOSH ZONE
S5... TUYERE PORTION
S6... FURNACEBOTTOMPORTION

38 CLAIMS
1. A bosh zone structure of a blast furnace in which a bosh zone is tubular and
is provided between a tuyere portion and a belly portion of the blast furnace, and has a
diameter expanding upward along a vertical direction, wherein:
the bosh zone has a sheet iron shell that is ring-shaped, a bosh zone stave made of copper or copper-alloy provided at an inner circumference of the sheet iron shell, and refiractory bricks provided at an inner circumference of the bosh zone stave;
a thickness of the refractory bricks in a horizontal direction at a top edge position of the bosh zone is 50 mm to 250 mm;
a thickness of the refractory bricks in the horizontal direction at a bottom edge position of the bosh zone is 200 mm to 500 mm; and
a narrow angle formed between a surface of the bosh zone stave and a horizontal plane is 75° to 82° in a cross section of the bosh zone including an axial line thereof
2. The bosh zone structure of the blast furnace according to Claim 1,
wherein a dimension in the vertical direction from a center of a tuyere provided
at the tuyere portion to the bottom edge position of the bosh zone is 1200 mm to 1350 mm; and
a dimension in the horizontal direction from a front end of the tuyere to the bottom edge position of the bosh zone is 700mm to 1100 mm.
3. The bosh zone structure of the blast furnace according to Claim 1 or 2,
wherein a dimension in the vertical direction from the center of the tuyere
provided at the tuyere portion to the top edge position of the bosh zone is 4500 mm to

39 5500 mm.
4. A design method of a blast furnace having a tuyere portion, a belly portion, and a tubular bosh zone which is provided between the tuyere portion and the belly portion, and has a diameter expanding upward along a vertical direction, wherein:
the bosh zone has a ring-shaped sheet iron shell, a bosh zone stave made of copper or copper-alloy provided at an inner circumference of a sheet iron shell, and refractory bricks provided at an iimer circumference of the bosh zone stave;
a thickness of the refractory bricks in a horizontal direction at a top edge position of the bosh zone is set to 50 mm to 250 mm;
a thickness of the refractory bricks in the horizontal direction at a bottom edge position of the bosh zone is set to 200 mm to 500 mm; and
a narrow angle formed between a surface of the bosh zone stave and a horizontal plane is set to 75° to 82° in a cross section of the bosh zone including an axial line thereof
Dated this 29/03/2012 /] /
[HRISHlKk^H R7^V€lWrDHURY]
^ OF REMFR)n& SAGAR
ATTORNEY FOR THE APMlCANTfS]