FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
RAW MATERIAL CHARGING DEVICE FOR
MELTING FURNACE;
POSCO, A CORPORATION ORGANISED AND EXISTING UNDER THE LAWS OF REPUBLIC OF KOREA, WHOSE ADDRESS IS (GOEDONG-DONG) 6261, DONGHAEAN-RO, NAM-GU, POHANG-SI, GYEONGSANGBUK-DO 37859, REPUBLIC OF KOREA
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

【DESCRIPTION】【Technical Field】
Disclosed is a charging device for uniformly distributing and charging raw materials into a melting furnace of a molten iron manufacturing facility.
【Background Art】
For example, in a FINEX facility which is a molten iron manufacturing facility that manufactures molten iron by reducing fine ore, hot compacted iron (HCI), which is a raw material, and coal briquettes, which are fuel, are charged into a melting furnace and then melted to manufacture molten iron, melted pig iron, and then steel is manufactured from the molten iron, and then the steel is supplied to demanders.
A charging device (gimbal distributor) is provided above the melting furnace to distribute and charge transported raw materials and fuel (hereinafter, raw materials and fuel are collectively referred to as 'raw materials') into the melting furnace in accordance with a working condition. The charging device is a device for uniformly distributing the raw materials into the melting furnace in accordance with the working condition in the melting furnace, and a rotating chute for changing a feed direction of the raw materials is installed at a lower end of the charging device.
The raw materials are charged into the melting furnace along an inclined surface of the rotating chute, and as a result, a distribution of the charging materials is determined finally by the rotating chute. The charging materials are

precisely controlled to be distributed at a desired point in the melting furnace, and because a size of the melting furnace is gradually increased, it is necessary to send the charging materials farther by increasing a discharge range of the charging materials from the rotating chute.
The discharge range of the charging materials may be increased by increasing a length of the rotating chute, but the length of the rotating chute is limited by a structure of the melting furnace and interference with other facilities. In addition, the discharge range of the charging materials may be increased by increasing a horizontal speed of the charging materials when increasing a height of the rotating chute, which is not suitable in terms of economic feasibility because the size of the facility is increased and it is difficult to control the facility.
【DISCLOSURE】
【Technical Problem】
The present invention has been made in an effort to provide a raw material charging device for a melting furnace which is capable of sending charging materials farther and more accurately under a condition in which a length of a rotating chute remains the same.
The present invention has also been made in an effort to provide a raw material charging device for a melting furnace which is capable of further increasing a discharge range of charging materials while minimizing damage to a rotating chute caused by the charging materials.
【Technical Solution】

An exemplary embodiment of the present invention provides a raw material charging device for a melting furnace, the raw material charging device including a rotating chute which is rotatably installed at a lower end of a feed pipe into which raw materials are introduced and controls a feed distribution of the raw materials, in which the rotating chute has a cross-sectional structure in which at least a part of an inner surface of the rotating chute is curved in an axial direction in which the raw materials are discharged.
Another exemplary embodiment of the present invention provides a raw material charging device for a melting furnace, the raw material charging device including a rotating chute which is rotatably installed at a lower end of a feed pipe into which raw materials are introduced and controls a feed distribution of the raw materials, in which the rotating chute has a cross-sectional structure in which an inner surface of a tip portion through which the raw materials are discharged is gradually curved inward.
The rotating chute may include a body portion which has an inlet directed toward the feed pipe, and a tip portion which is connected to a lower end of the body portion and has an outlet, and may have a structure in which an inner surface of the body portion and an inner surface of the tip portion may be continuously connected to each other so that a tangential line of the body portion and a tangential line of the tip portion coincide with each other.
The tip portion may be structured to be curved in an arc shape.
The body portion may have a cross-sectional structure in which the inner surface of the body portion is straight.
The body portion may have a cross-sectional structure in which the inner

surface of the body portion is curved.
The body portion may have a structure in which an inner diameter of the body portion is gradually decreased toward the tip portion and the inner surface of the body portion is inclined with respect to a central axis.
The body portion may have a structure in which an inner diameter of the body portion is constant in a movement direction of the raw materials.
The rotating chute may be formed such that a value of a diameter of an outlet is 4 or more when a value of a diameter of an inlet is 8.
The rotating chute may be formed such that a value of an overall length in an axial direction is 10 or more when the value of the diameter of the inlet is 8.
A ratio between a length of the body portion and a length of the tip portion may be 8:2 to 0:10 with respect to the overall length when the value of the overall length of the rotating chute is 10.
A radius of curvature of the inner surface of the tip portion may be (a+b)×0.2 or more. Here, a+b is the overall length of the rotating chute.
An inclination angle of the inner surface of the body portion with respect to the central axis of the body portion may be 0 to 11.3°.
The radius of curvature of the inner surface of the tip portion may be decreased as the inclination angle of the inner surface of the body portion with respect to the central axis of the body portion is decreased.
The rotating chute may have a cylindrical structure.
【Advantageous Effects】
According to the exemplary embodiment of the present invention, it is

possible to send the raw materials farther and more accurately under the same condition, in comparison with the related art, by increasing the discharge range by improving the structure of the rotating chute so that high acceleration and efficient kinetic energy may be obtained when the raw materials pass the inner surface of the rotating chute.
Therefore, it is possible to stably perform the operation in the melting furnace and to improve productivity by stably sending the raw materials farther even though the size of the melting furnace is increased.
In addition, it is possible to minimize damage to the rotating chute because the raw materials dropping into the rotating chute are smoothly discharged along the inner surface of the rotating chute without great impact.
In addition, it is possible to manufacture the rotating chute by spinning processing instead of welding in the related art, and as a result, it is possible to prevent the chute from being withdrawn.
【Description of the Drawings】
FIG. 1 is a schematic perspective view illustrating a raw material charging device for a melting furnace according to an exemplary embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view illustrating a rotating chute of the raw material charging device according to the present exemplary embodiment.
FIG. 3 is a cross-sectional view for explaining a structure of the rotating chute according to the present exemplary embodiment.

FIGS. 4 and 5 are a table and a graph illustrating comparisons of experimental results regarding raw material distribution distances between the rotating chutes according to the present exemplary embodiment and rotating chutes in the related art.
【Mode for Invention】
The technical terms used below are merely for the purpose of describing a specific exemplary embodiment, and not intended to limit the present invention. Singular expressions used herein include plural expressions unless they have definitely opposite meanings. The terms "comprises" and/or "comprising" used in the specification specify particular features, regions, integers, steps, operations, elements, components, but do not preclude the presence or addition of other particular features, regions integers, steps, operations, elements, components, and/or groups thereof.
Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily carry out the exemplary embodiments. It can be easily understood by those skilled in the art to which the present invention pertains that the following exemplary embodiments may be modified to various forms without departing from the concept and the scope of the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention.
Hereinafter, the present exemplary embodiment discloses an example of

a charging device (gimbal distributor) which is provided in a molten iron manufacturing facility called FINEX, mixes and charges hot compacted iron (HCI) and coal briquettes, which are raw materials, into a melting furnace, and controls a distribution of the raw materials.
The molten iron manufacturing facility includes a reducing furnace and a melting furnace. A charging device for uniformly charging the raw materials into the melting furnace is installed at an upper end of the melting furnace.
As illustrated in FIG. 1, a charging device 10 includes a feed pipe 20 which loads raw materials and fuel (hereinafter, raw materials and fuel are collectively referred to as 'raw materials'), which are conveyed to an upper end of the melting furnace, into the melting furnace, a rotating chute 30 which is disposed at a lower end of the feed pipe 20 and changes a discharge direction of the raw materials discharged from the feed pipe 20, and a drive unit 40 which rotates the rotating chute 30 in a desired discharge direction. Therefore, the rotating chute is rotated about the feed pipe 20 by the drive unit 40, and a tilting angle of the rotating chute 30 is changed in a circumferential direction, such that the raw materials are uniformly charged into the melting furnace.
As illustrated in FIGS. 2 and 3, the rotating chute 30 extends downward toward the interior of the melting furnace from the lower end of the feed pipe 20. The rotating chute 30 has a cylindrical shape opened at upper and lower ends thereof, the upper end is connected to the feed pipe 20 and defines an inlet 31 through which the raw materials are introduced, and the lower end defines an outlet 33 through which the raw materials are discharged. In the following description, an upper side or upside means a side directed upward along a

y-axis in FIG. 2, and a lower side or downside means a side directed in the opposite direction thereof. Further, an inner surface means an inner surface of the rotating chute along which the raw materials discharged from the feed pipe flow downward.
The rotating chute 30 may include an outer cover 32 which is made of steel and defines a cylindrical external shape, and a refractory material 34 which is attached to an outer circumferential surface of the outer cover 32. For example, the outer cover 32 may be made of stainless steel or heat-resistant steel. The inner surface of the rotating chute is a surface to which the raw materials are attached, that is, the inner surface of the rotating chute may mean an inner surface of the outer cover.
In the charging device 10 having the aforementioned structure, the rotating chute 30 according to the present exemplary embodiment may have a structure in which an inner surface of a tip portion 38 adjacent to the outlet through which the raw materials are discharged is gradually curved inward toward the tip portion adjacent to the outlet. Therefore, the rotating chute 30 is formed to have a cross-sectional structure in which the inner surface of the tip portion 38 is curved.
As illustrated in FIG. 3, the rotating chute 30 includes a body portion 36 which has the inlet 31 directed toward the feed pipe, and the tip portion 38 which is connected to the lower end of the body portion 36 and has the outlet 33. The tip portion 38 means a lower end portion of the rotating chute 30, and the body portion 36 means an upper end portion of the tip portion 38.
That is, in the present exemplary embodiment, the rotating chute 30 has

a cross-sectional structure in which the inner surface of the tip portion 38, which is the lower end portion of the rotating chute 30, is a curved surface curved inward. Therefore, a horizontal speed of the raw materials is increased while the raw materials flowing downward along the inner surface of the rotating chute 30 pass through the tip portion 38 of the rotating chute 30 which is curved to have a curved surface, and as a result, the raw materials may be discharged farther.
In the present exemplary embodiment, the body portion 36 and the tip portion 38 are smoothly and continuously connected to each other. Therefore, at a connection point, a tangential line of the inner surface of the body portion 36 and a tangential line of the inner surface of the tip portion 38 coincide with each other. That is, at the connection point between the inner surface of the body portion 36 and the inner surface of the tip portion 38, the inner surface of the body portion 36 and the inner surface of the tip portion 38 are continuously connected to each other without a bent, stepped, or discontinuous portion.
Since the inner surface of the body portion 36 and the inner surface of the tip portion 38 are smoothly and continuously connected to each other, the raw materials flowing downward along the inner surface of the rotating chute 30 may naturally flow downward without being caught at the connection point between the body portion 36 and the tip portion 38. Therefore, the rotating chute 30 according to the present exemplary embodiment enables the raw materials to move along the inner surface of the rotating chute 30 while minimizing a loss of kinetic energy while the raw materials pass between the body portion 36 and the tip portion 38. Since a loss of kinetic energy is reduced

while the raw materials flow downward along the rotating chute 30, a final escape speed may be increased at the outlet 33 of the tip portion 38 of the rotating chute 30.
As described above, in the rotating chute 30 according to the present exemplary embodiment, the inner surface of the body portion 36 and the inner surface of the tip portion 38 are continuously connected to each other, and the inner surface of the tip portion 38 is curved inward, such that a loss of kinetic energy of the raw materials is low, and a horizontal escape speed is increased at the outlet 33 of the tip portion 38, and as a result, a discharge range of the raw materials may be increased under the same condition.
The raw materials, which have dropped into the rotating chute 30 from the feed pipe, reach the outlet 33 at the lower end of the rotating chute 30 and then drop into the melting furnace, and the raw materials discharged from the rotating chute have a speed and a dropping angle while being separated from the rotating chute. As known, according to the following Equation 1 that indicates a William's trajectory effect, a horizontal dropping distance L of a particle is in proportion to a horizontal separation speed VH of the particle, density ρ of the particle, and a square of a size d of the particle.
Equation 1
That is, the dropping distance is increased as the density, the diameter,

and the horizontal speed of the particle are increased, and in the case of particles having the same density and the same diameter, the particle having a higher horizontal separation speed is moved farther.
Therefore, since the inner surface of the tip portion 38 of the rotating chute 30 according to the present exemplary embodiment is formed to be curved inward, the horizontal speed of the final escape speed of the raw materials passing through the tip portion 38 may be increased. Therefore, the discharge range may be increased because the horizontal separation speed of the raw materials is increased under the same condition.
In addition, in the present exemplary embodiment, the body portion and the tip portion are smoothly connected to each other without a discontinuous portion, and as a result, it is possible to manufacture the rotating chute through a spinning process by using a single member instead of welding in the related art. That is, in the case of a structure in the related art, there is a problem of cracks and withdrawal at a welding joint portion because a rotating chute is finally manufactured by welding multiple portions having inner surfaces with different inclination angles. In contrast, the rotating chute according to the present exemplary embodiment is designed such that the inner surfaces of the rotating chute are smoothly and integrally connected to each other without a discontinuous surface and a welding connection portion, and as a result, it is possible to manufacture the rotating chute only through the spinning process by using a single member. Therefore, the rotating chute according to the present exemplary embodiment may basically prevent a problem of withdrawal or cracks at a welded portion.

In the present exemplary embodiment, the body portion 36 may be formed to have a cross-sectional structure in which the inner surface of the body portion 36 is straight. Hereinafter, for the convenience of description, as illustrated in FIG. 3, it is assumed that a length of the body portion 36 is a, a length of the tip portion 38 is b, and an overall length of the rotating chute 30 is a+b. In addition, it is assumed that a diameter of the inlet 3 at the upper end of the rotating chute is A, and a diameter of the outlet 33 at the lower end of the rotating chute is B. Further, it is assumed that a line, which runs through a central axis of the rotating chute, is a central axis L, and an angle of the inner surface of the rotating chute with respect to the central axis L is an inclination angle c of the inner surface.
Because of the interference between the rotating chute and a peripheral
facility, ratios among the inlet, the outlet, and the overall length of the rotating
chute are approximately set. In the present exemplary embodiment, the
rotating chute 30 may be formed such that a value of the diameter B of the outlet is 4 or more when a value of the diameter A of the inlet is 8. If the value of the diameter B of the outlet 33 is less than 4, a size of the outlet is too small, such that it is difficult for the charging materials to pass through the outlet. Therefore, the value of the diameter B of the outlet is set to 4 or more based on the case in which the value of the diameter A of the inlet is 8, and the diameter B of the outlet may have a value when the value of the diameter A of the inlet is less than 8 in order to minimize interference with peripheral facilities. In addition, a value of the overall length a+b of the rotating chute may be 10 or more when the value of the diameter A of the inlet is 8. If the value of the overall length a+b of the

rotating chute is less than 10, a movement distance of the charging materials in the rotating chute is short, and as a result, a dropping distribution becomes short. Therefore, the value of the overall length of the rotating chute is 10 or more based on the case in which the value of the diameter of the inlet is 8, and the value of the overall length of the rotating chute may be increased within a range in which the interference with the peripheral facilities may be minimized.
The body portion 36 may be structured such that an inner diameter of the body portion 36 is gradually decreased toward the tip portion 38 and the inner surface of the body portion 36 is inclined with respect to the central axis L. As described above, since the inner surface of the body portion 36 is primarily formed to be inclined, it is possible to sufficiently increase the discharge range without rapidly reducing a radius of curvature of the inner surface of the tip portion 38 of the rotating chute 30.
In the present exemplary embodiment, a ratio between the length a of the body portion 36 and the length b of the tip portion 38 may be 8:2 to 0:10 with respect to the overall length when the value of the overall length of the rotating chute 30 in the axial direction is 10. The 0:10 means a structure in which the entire inner surface of the rotating chute is continuously curved from the inlet to the outlet.
If the ratio between the length a of the body portion 36 and the length b of the tip portion 38 exceeds the aforementioned range and the length b of the tip portion 38 is decreased from the ratio of 8:2, the radius of curvature of the tip portion is too small, and as a result, there is a problem in that the discharge range of the raw materials is decreased.

In addition, in the present exemplary embodiment, the radius of curvature of the inner surface of the tip portion 38 may be set to be equal to or more than 0.2 times the overall length a+b of the rotating chute.
In consideration of the ratio between the length A of the inlet and the length B of the outlet and the ratio between the length a of the body portion and the length b of the tip portion of the rotating chute, a minimum radius of curvature, which the tip portion may have, is a value set when the ratio between the length of the body portion and the length of the tip portion is 8:2. Therefore, the radius of curvature of the tip portion may not be smaller than (a+b)×0.2. Therefore, in the present exemplary embodiment, the radius of curvature of the inner surface of the tip portion may be equal to or more than (a+b)×0.2.
If the radius of curvature of the inner surface of the tip portion 38 is smaller than (a+b)×0.2, there is a problem in that the horizontal escape speed of the raw materials is decreased because the radius of curvature of the tip portion is too small.
Here, the radius of curvature of the inner surface of the tip portion 38 may be decreased as the inclination angle of the inner surface of the body portion 36 with respect to the central axis L of the body portion 36 is decreased.
That is, if the inclination angle of the inner surface of the body portion 36 is large, the horizontal speed of the raw materials passing through the body portion 36 is primarily increased, and as a result, the final horizontal escape speed of the raw materials may be maximally increased even though the radius of curvature of the tip portion 38 is large. On the contrary, if the inclination angle of the inner surface of the body portion 36 is small, it is possible to

increase the final horizontal escape speed of the raw materials by maximally decreasing the radius of curvature of the tip portion 38.
In the present exemplary embodiment, the inclination angle c of the inner surface of the body portion 36 with respect to the central axis L of the body portion 36 may be 0 to 11.3°.
In consideration of the ratio between the length A of the inlet and the length B of the outlet of the rotating chute and the overall length a+b of the rotating chute, the maximum inclination angle c, which the body portion may have, is a value set the length B of the outlet and the overall length a+b of the rotating chute are minimum values with respect to the length A of the inlet of the rotating chute. Therefore, the maximum value of the inclination angle C is a value set when the value of the length A of the inlet of the rotating chute is 8, the value of the length of the outlet is 4, and the value of the overall length is 10. Therefore, since the inclination angle C is 11.3° under the aforementioned condition, the inclination angle c according to the present exemplary embodiment may be 0 to 11.3°.
If the inclination angle of the inner surface of the body portion 36 is 0 degree, the inner diameter is constant in the movement direction of the raw materials. If the body portion 36 is structured to have a constant diameter, a contact angle between the raw materials dropping from the feed pipe and the inner surface of the body portion 36 may be minimized. Therefore, it is possible to increase an initial speed of the raw materials and to discharge the raw materials farther through the tip portion 38.
If the inclination angle c exceeds 11.3°, the length of the body portion is

increased, and the length of the tip portion is decreased, and as a result, there is a problem in that the horizontal escape speed of the raw materials is decreased because the radius of curvature of the tip portion is too small.
In addition to the aforementioned structure, the body portion 36 may be formed to have a cross-sectional structure in which the inner surface of the body portion 36 is curved. In this structure, the entire inner surface of the rotating chute 30 including the body portion 36 and the tip portion 38 is continuously curved from the inlet 31 to the outlet 33. The inner surface of the rotating chute may be curved to entirely have a constant radius of curvature from the inlet 31 to the outlet 33, or the radius of curvature of the rotating chute may be gradually decreased from the inlet 31 to the outlet 33. Even in the structure in which the inner surface of the body portion 36 is curved as described above, the body portion 36 and the tip portion 38 are continuously curved, and the horizontal escape speed of the raw materials is increased by the tip portion 38, such that the discharge range may be increased.
FIGS. 4 and 5 are a table and a graph illustrating comparison of discharge ranges of various rotating chutes according to the present exemplary embodiment with discharge ranges of rotating chutes in the related art.
In FIG. 4, the rotating chutes according to Examples and Comparative Examples have the same length in the axial direction, the inlets with the same diameter, and the outlets with the same diameter.
The Comparative Examples are the rotating chutes having the structures in the related art, Comparative Example 1 is a conical rotating chute having a cross-sectional structure in which the inner surface thereof is straight, and

Comparative Example 2 is a conical rotating chute having a cross-sectional structure in which the inner surface thereof is straight and bent to have multiple steps at the portion adjacent to the outlet.
All of Examples 1 to 4 are rotating chutes according to the present invention each having a cross-sectional structure in which a part of the inner surface including the inner surface of the tip portion is curved and the body portion and the tip portion are continuously connected to each other.
As illustrated in FIG. 5, in the case of Comparative Example 1, the discharge range of the raw materials is not large, such that the discharge range does not reach 6 m even in a state in which the rotating chute is tilted at 30 degrees. Comparative Example 2 has a structure in which the inclination angle of the inner surface adjacent to the outlet is increased in a multi-stepped manner, and it can be seen that the discharge range of the raw materials is increased to 6.9 m in comparison with Comparative Example 1.
In the case of the Examples in which the body portion and the tip portion are continuously connected to each other and the tip portion is curved, it can be seen that the discharge range is entirely increased in comparison with the Comparative Examples. In the Examples, in the case in which the ratio between the body portion and the tip portion is 5:5, the discharge range of the raw materials may be increased to 7.4 m by maximally reducing the inclination angle of the body portion and increasing the radius of curvature of the tip portion.
In addition, in the Examples, in the case in which the length of the tip portion is decreased so that the ratio between the body portion and the tip portion is 7:3, the radius of curvature of the tip portion may be further decreased,

and as a result, the discharge range of the raw materials may be sufficiently increased even in the case in which the inclination angle of the body portion is increased.
As described above, it is possible to maximally increase the discharge range of the raw materials in comparison with the related art through lots of experiments in respect to various rotating chutes each having a curved shape by appropriately setting the ratio between the body portion and the tip portion and the radius of curvature of the tip portion.
Therefore, according to the present exemplary embodiment, it is possible to increase the discharge range of the raw materials by increasing the horizontal escape speed of the raw materials by improving the structure of the rotating chute, and it is possible to increase the lifespan of the rotating chute by reducing stress applied to the rotating chute by the raw materials.
In addition, in the case of the rotating chute having a curved shape according to the present exemplary embodiment, there is an advantage in that a degree of damage to a damaged surface of the chute is small in comparison with the Comparative Examples even though the discharge distances are equal in the Examples and the Comparative Examples. Since the inner surfaces of Comparative Examples are straight and thus have bent portions, kinetic energy of the charging materials is concentrated on the bent portion. Therefore, the damage is concentrated at the bent portion.
In contrast, according to the present exemplary embodiment, damage to the chute is reduced because the inner surfaces are curved and smoothly connected to each other and thus kinetic energy of the charging materials is

dispersed throughout the entire curved surface.
While the exemplary embodiment of the present invention has been illustrated and described above, various modifications and other exemplary embodiments may be implemented by those skilled in the art. It is noted that all of the modifications and other exemplary embodiments are contemplated and included in the appended claims, and do not depart from the true purpose and the scope of the present invention.

10 : Charging device 20 : Feed pipe
30 : Rotating chute 32 : Outer cover
34 : Refractory material 40 : Drive unit

We Claim: 【Claim 1】
A raw material charging device for a melting furnace, the raw material charging device including a rotating chute which is rotatably installed at a lower end of a feed pipe into which raw materials are introduced and controls a feed distribution of the raw materials,
wherein the rotating chute has a cross-sectional structure in which an inner surface of a tip portion through which the raw materials are discharged is curved inward.
【Claim 2】
The raw material charging device of claim 1, wherein:
the rotating chute includes a body portion directed toward the feed pipe,
and a tip portion connected to a lower end of the body portion, and
an inner surface of the body portion and an inner surface of the tip
portion are continuously connected to each other.
【Claim 3】
The raw material charging device of claim 2, wherein: the tip portion is curved in an arc shape.
【Claim 4】

The raw material charging device of claim 2, wherein:
the body portion has a cross-sectional structure in which the inner surface of the body portion is straight.
【Claim 5】
The raw material charging device of claim 2, wherein:
the body portion has a cross-sectional structure in which the inner surface of the body portion is curved.
【Claim 6】
The raw material charging device of claim 3, wherein:
the body portion has a structure in which an inner diameter of the body portion is constant in a movement direction of the raw materials.
【Claim 7】
The raw material charging device of claim 1, wherein:
the rotating chute is formed such that a value of a diameter of an outlet is 4 or more when a value of a diameter of an inlet is 8.
【Claim 8】
The raw material charging device of claim 7, wherein:
the rotating chute is formed such that a value of an overall length in an

axial direction is 10 or more when the value of the diameter of the inlet is 8.
【Claim 9】
The raw material charging device of claim 8, wherein:
a ratio between a length of the body portion and a length of the tip portion
is 8:2 to 0:10 with respect to the overall length when the value of the overall
length of the rotating chute is 10.
【Claim 10】
The raw material charging device of claim 9, wherein:
a radius of curvature of the inner surface of the tip portion is (a+b)×0.2 or more,
in which a+b is the overall length of the rotating chute.
【Claim 11】
The raw material charging device of claim 10, wherein:
the body portion has a structure in which an inner diameter of the body
portion is gradually decreased toward the tip portion and the inner surface of the
body portion is inclined with respect to a central axis.
【Claim 12】
The raw material charging device of claim 11, wherein:

an inclination angle of the inner surface of the body portion with respect to the central axis of the body portion is 0 to 11.3°.
【Claim 13】
The raw material charging device of claim 12, wherein:
the radius of curvature of the inner surface of the tip portion is decreased
as the inclination angle of the inner surface of the body portion with respect to
the central axis of the body portion is decreased.
【Claim 14】
The raw material charging device of claim 13, wherein: the rotating chute has a cylindrical structure.