JP2007147195A - Material input method into rotary hearth furnace, and reduction treatment method of iron oxide by rotary hearth furnace using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for inputting a material containing an auxiliary substance into a rotary hearth furnace without degrading productivity by a material supply means of one system; and to provide a reduction treatment method of iron oxide by a rotary hearth furnace using the material input method. <P>SOLUTION: This material input method is used for dividing a material comprising a mixture of agglomerate 2a and an auxiliary substance 2b into the agglomerate 2a and the auxiliary substance 2b by using an input chute 6 having a sieve means 3 to input them into circumferential different dropping positions on a rotary hearth 10 in moving. This reduction treatment method is used for subjecting, to a reduction treatment, a material being a mixture of agglomerate 2a formed of iron oxide such as ironstone or iron-making dust and an auxiliary substance 2b formed of a reducing agent such as coal or coke by a rotary hearth furnace 1 by inputting, by using the material input method, the auxiliary substance 2b and the agglomerate 2a on the upstream side on the rotary hearth 10 in moving and on the upper surface of the auxiliary agent 2b on the downstream side, respectively. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for charging a raw material containing an auxiliary substance into a rotary hearth furnace, and a method for reducing iron oxide by a rotary hearth furnace using the raw material charging method.

  The rotary hearth furnace is composed of an outer peripheral wall, an inner peripheral wall, and an annular rotary hearth disposed between these walls. And the said rotary hearth is comprised with the annular | circular shaped furnace body frame, the hearth heat insulating material arrange | positioned on the said furnace body frame, and the refractory material arrange | positioned on this hearth heat insulating material.

  Such a rotary hearth has a meshing mechanism between a pinion gear driven by a rotating shaft provided at the bottom of the hearth and a rack rail fixed circumferentially to the bottom of the furnace body frame, and a circular on the floor surface. It is rotationally moved by a combination of a track laid in a circumferential shape and a plurality of drive wheels provided on the bottom of the furnace body frame.

  The rotary hearth furnace having the above-described structure is used for heat treatment of metals such as steel billets or combustion treatment of combustible waste, and recently, reduced iron is produced from iron oxide using a rotary hearth furnace. The method is drawing attention. An example of a reduced iron manufacturing process using a rotary hearth furnace will be described below with reference to the schematic diagram of the equipment configuration of the rotary hearth furnace according to the conventional invention shown in FIG. 3 (see, for example, Patent Document 1).

(1) Powdered iron oxide (iron ore, electric furnace dust, etc.) and powdered carbonaceous reducing agent (coal, coke, etc.) are mixed and granulated to produce raw pellets or briquettes.
(2) The raw pellets are heated to a temperature range in which combustible volatile matter generated from the pellets does not ignite to remove adhering moisture to obtain dry pellets. If the moisture content is briquette, it may be used without drying.

(3) This dry pellet (raw material 14) is supplied into the rotary hearth furnace 16 using an appropriate charging device 12, and the pellet having a thickness of about 1 to 2 pellets on the rotary hearth 11 Form a layer.
(4) The pellet layer is reduced by radiant heating by combustion of a burner 17 installed in the upper part of the furnace, and metallization proceeds.

(5) The metallized pellet is cooled by the cooler 18. Cooling in this case is performed by blowing gas directly onto the pellets, or indirectly cooling with a water cooling jacket, etc., and the discharge device after expressing mechanical strength that can withstand handling during and after discharge 13 is discharged outside the furnace.
(6) Immediately after discharging the metallized pellets (reduced iron 15), dry pellets (raw material 14) are charged, and the above process is repeated to produce reduced iron.

  In the rotary hearth furnace for producing reduced iron in this way, when the raw materials are charged, the raw materials are laid on the rotary hearth in a uniform thickness in order to uniformly heat all the raw materials. It becomes important. For this purpose, raw materials are supplied to the rotary hearth furnace using a vibratory feeder or a screw feeder. In some cases, a screw-type material leveling device is used to eliminate the unevenness of the material on the hearth.

As a conventional example of a raw material supply apparatus for supplying a raw material to such a rotary hearth furnace, there is a raw material supply apparatus of FIG. 4 showing an embodiment thereof (see Patent Document 2).
That is, this raw material supply device is a rotary hearth raw material supply device that supplies raw materials using a vibrating conveyor, and the vibrating conveyor includes an outer frame 23 that guides the raw material and a horizontal or inclined bottom surface 24. Have.

A mesh 25 having a mesh opening smaller than the average diameter of the raw material and horizontal or inclined is provided above the bottom surface 24 as a raw material conveyance and supply surface. The mesh 25 is fixed to the outer frame 23 by a line 27. And a vibration device 26 that vibrates the outer frame 23 and / or the bottom surface 24. Then, as shown by the arrows in the figure, when the large diameter raw material 21 and the small diameter raw material 22 are loaded together on the net 25, the vibration device 26 vibrates the outer frame 23, and this vibration is applied to the net 25. Then, the small diameter raw material 22 is shaken off under the net 25.
JP 2001-181720 A Japanese Patent Application Laid-Open No. 2004-218995

  However, in the rotary hearth furnace for producing reduced iron, an auxiliary agent that promotes the reaction of the raw material or substitutes for the fuel may be supplied together with the raw material. In this case, first, the auxiliary agent is supplied to the rotary hearth so as to have a uniform thickness, and then the raw material is supplied uniformly to the upper surface of the auxiliary agent. It is necessary to avoid covering and heating the raw material.

An example of a conventional raw material charging method to the rotary hearth furnace in such a case will be described below with reference to a schematic configuration diagram showing a raw material charging portion of the rotary hearth furnace according to the conventional example of FIG.
That is, in the conventional raw material charging unit, first, the auxiliary agent 33 is supplied to the upstream side of the rotary hearth 10 moving in the direction of the arrow by the auxiliary agent supply device 32 of the first stage, and then the second stage. The raw material supply device 30 puts the raw material 31 on the upper surface of the auxiliary agent 33 on the downstream side.

  In this case, two supply systems for the auxiliary agent 33 and the raw material 31 are required, and the proportion of the raw material charging portion in the entire rotary hearth furnace 1 is increased, so that the necessary processing time is ensured. Thus, the rotational speed had to be lowered, and the productivity was significantly reduced. Furthermore, in order to eliminate the unevenness of the raw material 31 and the auxiliary agent 33 on the hearth 10, a screw-type raw material leveling device 34 is used.

  Accordingly, an object of the present invention is to provide a method for feeding a raw material containing an auxiliary agent into a rotary hearth furnace without reducing productivity by a single supply means, and a rotary hearth furnace using this raw material charging method. An object of the present invention is to provide a method for reducing iron oxide.

  In order to achieve the above-mentioned object, the means adopted by the raw material charging method of the rotary hearth furnace according to claim 1 of the present invention is a mixture of an agglomerate and an auxiliary agent in the raw material charging method to the rotary hearth furnace. The raw material consisting of is separated into the agglomerated material and the auxiliary agent using a charging chute having a sieving means, and is charged at different dropping positions in the circumferential direction on the moving rotary hearth. .

  The means adopted by the method for reducing iron oxide by a rotary hearth furnace according to claim 2 of the present invention comprises an agglomerate composed of iron oxide such as iron ore and iron dust, and a reducing agent such as coal and coke. A raw material that is a mixture with an auxiliary agent is added to the upstream side of the moving rotary hearth using the raw material charging method to the rotary hearth furnace according to claim 1, and the auxiliary agent on the downstream side. The agglomerated material is put on the upper surface of the steel, and the raw material is reduced by a rotary hearth furnace.

  The means employed in the raw material charging method or iron oxide reduction treatment method according to claim 3 of the present invention is the raw material charging method into the rotary hearth furnace according to claim 1 or claim 2. In the iron oxide reduction treatment method described above, the sieving surface clearance dimension of the sieving means is 4 to 10 mm.

  The means employed by the raw material charging method or iron oxide reduction method according to claim 4 of the present invention is the raw material charging method to the rotary hearth furnace according to claim 1 or claim 2. In the iron oxide reduction treatment method described above, the sieving surface is a comb-like sieve.

  The means adopted in the raw material charging method or iron oxide reduction treatment method according to claim 5 of the present invention is the raw material charging method or iron oxide reduction method in the rotary hearth furnace according to claim 3. In the processing method, the sieve surface is a comb-like sieve.

  A raw material charging method for a rotary hearth furnace according to claim 1 of the present invention is that a raw material comprising a mixture of agglomerated material and an auxiliary agent is converted into the agglomerated material and auxiliary agent using an input chute having a sieving means. Separation and introduction of the raw material containing the auxiliary agent into one of the raw material supply means can be efficiently performed because the separation can be performed at different dropping positions in the circumferential direction on the moving rotary hearth.

  The method for reducing iron oxide by a rotary hearth furnace according to claim 2 of the present invention comprises an agglomerate composed of iron oxide such as iron ore or iron dust, and an auxiliary agent composed of a reducing agent such as coal or coke. Using the raw material charging method of the rotary hearth furnace according to claim 1, the auxiliary material on the upstream side of the moving rotary hearth and the auxiliary agent on the upper surface of the auxiliary agent on the downstream side. Since the agglomerated material is charged and the iron oxide is reduced by a rotary hearth furnace, the iron oxide can be produced with high productivity.

  In the raw material charging method or iron oxide reduction treatment method according to claim 3 of the present invention, the sieving surface gap size of the sieving means is 4 to 10 mm. Therefore, the agglomerated material constituting the raw material And the auxiliary agent can be reliably separated.

  In the raw material charging method or iron oxide reduction method according to claim 5 of the present invention, the sieving surface of the sieving means is a comb-like sieving, so that clogging is difficult.

  First, a raw material charging method to a rotary hearth furnace according to an embodiment of the present invention and an iron oxide reduction treatment method using the rotary hearth furnace using the same will be described below with reference to FIGS. 1 and 2. . FIG. 1 is a schematic configuration diagram showing a raw material charging method to a rotary hearth furnace according to an embodiment of the present invention in a vertical section along the circumference of the rotary hearth furnace, and FIG. It is a schematic plan view which shows arrow AA.

  Reference numeral 6 in the figure indicates a charging chute according to the embodiment of the present invention for charging the raw material 2 into the rotary hearth furnace 1. The charging chute 6 is provided in the raw material supply region of the rotary hearth furnace 1 with the sieving means 3, the vertical wall surface 4 formed on the wall of the furnace body facing the sieving means 3, and the sieving means 3 It is comprised from the raw material injection | throwing-in space 5 formed between the substantially vertical wall surfaces 4. FIG. The raw material charging method using the charging chute 6 to the rotary hearth furnace 1 and the iron oxide reduction treatment method using the rotary hearth furnace 1 using this raw material charging method will be described in detail later.

  On the other hand, the rotary hearth furnace 1 according to the embodiment of the present invention will be described in more detail. The rotary hearth furnace 1 includes an outer peripheral wall, an inner peripheral wall, and an annular rotary hearth 10 arranged between them. And this rotary hearth 10 has comprised the structure which rotates between the outer peripheral wall and an inner peripheral wall with the drive device which is not shown in figure. The rotary hearth 10 is composed of an annular hearth frame, a hearth heat insulating material disposed on the hearth frame, and a refractory disposed on the hearth heat insulating material. .

  And the raw material 2 which consists of a mixture of an agglomerated material and an adjuvant is supplied to the sieving surface 3a of the sieving means 3 from the outside of the furnace via the raw material supplying means 7, and the raw material 2 is agglomerated by this sieving means 3. 2a and auxiliary agent 2b are separated and put on the rotary hearth 10. Then, the raw material 2 is subjected to treatment such as heating and reduction while rotating the rotary hearth 10 in the direction of the arrow at a low speed.

  The raw material supply means 7 can be a vibration feeder or a screw feeder. From the viewpoint of evenly dispersing and dropping the raw material 2 on the sieving surface 3a of the sieving means 3 in the hearth width direction, the vibration feeder is used. Is preferred.

  The raw material 2 made of a mixture of agglomerated material and auxiliary agent is separated into the agglomerated material 2a and auxiliary agent 2b by the sieving means 3 constituting the charging chute 6, and the rotating hearth in motion 10 It is comprised so that it may inject | pour into the different fall position of the upper circumferential direction.

  That is, the auxiliary agent 2b has a powdery form and has a smaller size than the agglomerated product 2a formed in a pellet form. Therefore, the auxiliary agent 2b is smaller than the agglomerate 2a, and by using the charging chute 6 having the sieving means 3 composed of the sieving surface 3a of the gap larger than the auxiliary agent 2b, as shown in FIG. The auxiliary agent 2b passes through the clearance of the sieving surface 3a and is introduced to the upstream side of the moving rotary hearth 10. Since the lower surface of the sieving means 3 is an open surface, the auxiliary agent 2b that has passed through the gap of the sieving surface 3a is put on the rotary hearth 10 directly below.

  On the other hand, the agglomerated material 2a is captured by the sieving surface 3a and is put on the upper surface of the auxiliary agent 2b on the downstream side. Thereafter, if necessary, the level of the raw material 2 charged on the rotary hearth 10 may be made uniform by the raw material leveling means 8. By such an operation, the heating to the raw material 2 can be made uniform.

  A manhole 9 is preferably provided on the vertical wall surface 4 constituting the charging chute 6. When the sieving surface 3a of the sieving means 3 is clogged or damaged, the manhole 9 can be opened to perform maintenance for repairing or replacing the sieving surface 3a.

  As described above, the raw material 2 composed of the mixture of the agglomerated material 2a and the auxiliary agent 2b is charged into the rotary hearth furnace 1 by the charging method as described above. However, it has become possible to efficiently separate and input with one system of raw material supply means.

  Further, using such a raw material charging method to the rotary hearth furnace 1, a mixture of an agglomerate composed of iron oxide such as iron ore and ironmaking dust and an auxiliary agent composed of a reducing agent such as coal and coke is used. The raw material 2 is charged with the auxiliary agent 2a on the upstream side of the moving rotary hearth 10 and the agglomerate 2b is introduced on the upper surface of the downstream auxiliary agent 2a. The raw material 2 can be reduced to obtain iron oxide.

  On the other hand, the sieving means 3 may have a sieving surface 3a of a stationary type, but may also be a vibration sieving machine having a vibration function for applying vibration to the sieving surface 3a. The sieving surface 3a is preferably composed of a mesh, and more preferably composed of a comb shape. When the sieving surface 3a is comb-shaped, it is preferable that the direction of the comb is oriented in a direction substantially parallel to the rotation direction of the rotary hearth 10.

  Further, such a sieving surface 3a faces the rotational direction of the rotary hearth 10 as shown in FIG. 1 so that the agglomerate 2b is captured on the upper surface and easily falls along the sieving surface 3a. It is preferable that it is configured to be inclined. The inclination angle of the sieving surface 3a is preferably in the range of 30 to 45 degrees with respect to the horizontal plane.

  Moreover, it is preferable that the clearance dimension of this sieving surface 3a is the range of 4-10 mm. When the sieving surface 3a is formed in a comb shape, the gap size refers to a gap size between combs that form a comb shape. If the gap dimension is less than 4 mm, a part of the auxiliary agent 2b is trapped by the sieving surface 3a and cannot pass through the gap. Conversely, if the gap dimension exceeds 10 mm, the agglomerated product This is because some of 2a slips through the gap of the sieving surface 3a.

  And using the input chute 6 having the sieving means 3 having the above-described configuration, an agglomerate composed of iron oxide such as iron ore and iron-making dust and an auxiliary agent composed of a reducing agent such as coal and coke. The raw material 2 which is a mixture can be put on the moving rotary hearth 10 and reduced by the rotary hearth furnace 1 to obtain iron oxide.

  As described above, the raw material charging method of the rotary hearth furnace according to the present invention uses a charging chute having a sieving means for the raw material consisting of a mixture of the agglomerated material and the auxiliary agent. Therefore, it is possible to efficiently separate and charge by a single material supply means.

  In addition, using the raw material charging method to the rotary hearth furnace according to the present invention, a mixture of agglomerates composed of iron oxide such as iron ore and iron dust and an auxiliary composed of a reducing agent such as coal and coke. Since a certain raw material is charged with the auxiliary agent on the upstream side of the moving rotary hearth and the agglomerate is put on the upper surface of the auxiliary agent on the downstream side, the iron oxide is reduced by the rotary hearth furnace. Iron oxide can be produced with high productivity.

It is the typical block diagram which showed the raw material injection | throwing-in method to the rotary hearth furnace which concerns on embodiment of this invention with the vertical cross section along the periphery of the said rotary hearth furnace. It is a typical top view which shows arrow AA of FIG. It is the schematic of the equipment structure of the rotary hearth furnace which concerns on a prior art example. It is the figure which showed one Embodiment of the raw material supply apparatus of the rotary hearth furnace which concerns on a prior art example. It is a typical block diagram which shows the raw material input part of the rotary hearth furnace which concerns on a prior art example.

Explanation of symbols

1 ... Rotary hearth furnace,
2 ... Raw material, 2a ... Agglomerate, 2b ... Adjuvant,
3 ... sieving means, 3a ... sieving surface,
4 ... Vertical wall surface, 5 ... Raw material input space, 6 ... Input chute,
7 ... Raw material supply means, 8 ... Raw material leveling means, 10 ... Rotary hearth

Claims (5)

  In the raw material charging method to the rotary hearth furnace, the raw material consisting of the mixture of the agglomerated material and the auxiliary agent is separated into the agglomerated material and the auxiliary agent by using the charging chute having the sieving means, and the rotating while moving A raw material charging method for a rotary hearth furnace, wherein the raw material is charged at different dropping positions in the circumferential direction on the hearth.   The raw material input method to the rotary hearth furnace according to claim 1, wherein a raw material that is a mixture of an agglomerate composed of iron oxide such as iron ore and iron dust and an auxiliary agent composed of a reducing agent such as coal or coke is used. The above-mentioned auxiliary agent is introduced into the upstream side of the moving rotary hearth and the agglomerate is introduced into the upper surface of the downstream auxiliary agent, and the raw material is reduced by the rotary hearth furnace. A method for reducing iron oxide, which is characterized.   The method for charging a raw material into a rotary hearth furnace according to claim 1 or the method for reducing iron oxide according to claim 2, wherein a sieving surface gap size of the sieving means is 4 to 10 mm.   The method for charging a raw material into a rotary hearth furnace according to claim 1 or the method for reducing iron oxide according to claim 2, wherein the sieving surface is a comb-like sieve. The method for charging a raw material into a rotary hearth furnace or the method for reducing iron oxide according to claim 3, wherein the sieving surface is a comb-like sieve.

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