JP6644458B2 - Molding machine - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a molding machine for molding an agglomerate raw material to produce a high-strength agglomerate with good yield.

  In recent years, from the viewpoint of resource saving and energy saving, iron oxide-containing substances such as fine iron ore, iron-containing dust, scale, and sludge generated in steelworks, etc., and carbon oxide reducing substances have been mixed and agglomerated. The agglomerate is charged into a rotary hearth furnace in which the hearth rotates horizontally and heated to 1000 to 1400 ° C., and the iron oxide in the iron oxide-containing substance is reduced to a carbonaceous reducing substance while the hearth makes one round. (Patent Documents 1 to 6, for example).

  Fig. 1 shows that an agglomerate containing an iron oxide-containing substance and a carbonaceous reducing substance is manufactured, placed on the hearth of a rotary hearth-type reduction furnace, and heated to reduce iron oxide in the iron oxide-containing substance. Shows a series of steps for producing reduced iron.

  Iron oxide-containing substances such as iron making dust and iron ore, carbonaceous reducing substances such as carbonaceous materials, and other necessary auxiliary materials are cut out from the hopper 1 and mixed while being pulverized by a pulverizer / mixer 2 (for example, a ball mill). And

  The mixed raw material is fed to the kneading machine 3 as needed, and kneaded by adding water and / or a binder. Next, it is fed to the molding machine 4 and molded to form a compact of, for example, 5 to 40 mm.

  The agglomerate is dried by the dryer 5 and placed on the hearth of the rotary hearth reducing furnace 10 from the charging part 7 of the charging device 6 of the rotary hearth reducing furnace 10.

  The rotary hearth type reduction furnace 10 includes a burner 11, and the agglomerate 8 placed on the hearth of the rotary hearth type reduction furnace 10 is heated by the air supplied to the burner 11 and the combustion heat of the fuel. Is done. While the rotary hearth reducing furnace 10 rotates in the direction of the arrow, the iron oxide in the iron oxide-containing substance constituting the agglomerate 8 is reduced by the carbonaceous reducing substance in the agglomerate 8. Exhaust gas generated in the furnace is discharged from the furnace through the exhaust gas pipe 12 and sent to an exhaust gas treatment facility (not shown).

  The agglomerates containing reduced iron generated in the rotation of the rotary hearth-type reduction furnace 10 are discharged out of the furnace by the discharge device 9 (for example, screw means). Then, the reduced iron is conveyed to a melting furnace (not shown) by, for example, a conveying means (not shown), and is converted into hot metal by reaction heat of coal and oxygen.

  In this series of manufacturing steps, the strength (particularly, crushing strength) and yield of the agglomerate 8 molded by the molding machine greatly affect the productivity of the rotary hearth type reduction furnace 10.

  Patent Document 7 discloses a briquette that controls the rotation speed of a screw feeder based on the rotation speed of a pressure roll that pressurizes a raw material and adjusts the amount of the raw material pushed into the pressure roll in the production of a carbon material-containing metal oxide briquette. A machine (molding machine) is disclosed. However, it does not disclose the strength and yield of the carbon material-containing metal oxide briquettes.

  The screw feeder is provided with a blade for preventing the material from adhering to the inner wall surface of the hopper, but the blade does not contribute to the adjustment of the amount of the material pressed into the pressure roll.

  Patent Literature 8 discloses a coal fuel pulverizing supply device having a rotary screw therein and a coal feed pipe for feeding coal to a vertical mill. Patent Document 8 discloses that in order to promote the introduction of coal into a coal feed pipe and to prevent coal from adhering to the blade surface and becoming a missing carbon, the angle of the screw blade with respect to the horizontal is changed from the upper end to the lower end. , But no specific angle is disclosed.

JP-A-10-317033 JP 2001-020005 A JP 2001-181720 A JP 2002-129218 A JP 2003-027118 A JP 2003-183716 A JP 2008-260982 A JP-A-07-155625

  As described above, the strength (particularly, crushing strength) and yield of the agglomerate formed by the forming machine greatly affect the productivity of the rotary hearth type reduction furnace.

  If the strength of the agglomerate is low, the agglomerate is cracked and powdered during the process of transporting the agglomerate to the rotary hearth type reduction furnace or charging the agglomerate into the furnace. Further, in the process of heating and reducing the agglomerate in the furnace, the agglomerate is partially cracked and powdered. The agglomerate powder is deposited on the hearth of a rotary hearth-type reduction furnace, heated, fused and solidified to form a deposited layer. When the thickness of the deposited layer increases, the productivity of the rotary hearth-type reduction furnace naturally decreases.

  Further, when the yield of the agglomerate is low, the amount of the agglomerate to be transported and charged into the rotary hearth type reduction furnace is limited, so that the productivity of the rotary hearth type reduction furnace decreases. Therefore, in a molding machine that is charged into a rotary hearth-type reduction furnace (see FIG. 1) to produce agglomerates to be placed on the hearth, high-strength agglomerates are produced with good yield. Is required.

  Therefore, in view of the above demand, the present invention has an object to provide a molding machine that manufactures the above-mentioned agglomerates, to produce high-strength agglomerates with a good yield, and to provide a means for solving the problems. With the goal.

  The present inventors have investigated the causes of the decrease in the strength and yield of agglomerates, and have intensively studied means for solving the above problems.

  As a result of the investigation, when the raw material for agglomeration is refined, (i) the voids in the raw material for agglomeration increase and the voids in the agglomerate increase, and (ii) the adhesive force of the raw material for agglomeration It was found that the strength and yield of the agglomerate were reduced due to the fact that the amount of the agglomerate to be pressed into the space between the pair of forming rolls was not stable.

  Based on the above findings, as a result of intensive studies on the means for solving the above problems, the pitch difference of the screw blades provided at the tip of the screw feeder that pushes the agglomerate between a pair of forming rolls, from the tip to the rear end If the angle of the screw blade with respect to the horizontal is increased from the leading end to the trailing end, (i) the voids in the agglomerate to be pressed between the pair of forming rolls can be reduced. It has been found that voids in the agglomerate can be reduced, and that (ii) the amount of agglomerate to be pressed between a pair of forming rolls can be stabilized even if the adhesive force of the agglomerate is increased. .

  The present invention has been made based on the above findings, and the gist is as follows.

(1) In a molding machine in which an agglomerate material containing an iron oxide-containing material and a carbonaceous reducing material is pushed between a pair of molding rolls by one or more screw feeders
(I) The blade angle of the screw blade provided at the leading end of the screw feeder increases continuously or stepwise from the leading end to the trailing end, and
(Ii) Molding characterized in that the blade angle at the rear end of the screw blade is (the blade angle at the tip of the screw blade) × 1.9 or more and (the blade angle at the tip of the screw blade) × 2.5 or less. Machine.

  (2) The molding machine according to (1), wherein the width of the screw blade is increased from a leading end to a rear end of the screw blade.

  ADVANTAGE OF THE INVENTION According to this invention, since the agglomerate charged to a rotary hearth-type reduction furnace and mounted on a hearth can be manufactured with high strength and high yield, the productivity of the molding machine is significantly improved. .

An agglomerate containing an iron oxide-containing substance and a carbonaceous reducing substance is manufactured, placed on the hearth of a rotary hearth-type reduction furnace, heated, and reduced to reduce iron oxide in the iron oxide-containing substance. It is a figure which shows a series of process which manufactures. It is a figure showing one mode of the conventional molding machine. It is a figure showing one mode of the molding machine of the present invention. It is a figure showing one mode of the screw feeder used by the molding machine of the present invention. (A) shows the aspect of the screw feeder, and (b) shows the aspect of the screw feeder viewed from the tip of the screw feeder. FIG. 4 is a diagram showing the relationship between the rotation speed (rpm) of a screw blade and the rotation speed (rpm) of a molding roll in a conventional molding machine and the molding machine of the present invention. It is a figure which shows the relationship between briquette porosity (%) and crushing strength (kg / p) in the conventional molding machine and the molding machine of this invention. It is a figure which shows the angle ratio which divided the blade angle of the rear end of a screw blade by the blade angle of the front end of a screw blade, and the relationship between agglomerate yield (%).

The molding machine of the present invention (hereinafter sometimes referred to as the “molding machine of the present invention”) forms a pair of agglomerated raw materials containing an iron oxide-containing substance and a carbonaceous reducing substance using one or more screw feeders. In a molding machine that pushes between rolls,
(I) The blade angle at the tip of the screw blade provided at the tip of the screw feeder increases continuously or stepwise toward the rear end of the screw blade, and
(Ii) Molding characterized in that the blade angle at the rear end of the screw blade is (the blade angle at the tip of the screw blade) × 1.9 or more and (the blade angle at the tip of the screw blade) × 2.5 or less. Machine.

  Hereinafter, the molding machine of the present invention will be described with reference to the drawings. First, FIG. 2 shows an embodiment of a conventional molding machine used as the molding machine 4 shown in FIG.

  The molding machine 4 includes a pair of molding rolls 4a, 4a which are rotated by an electric motor 4n. The agglomerate 3a fed into the hopper 1a is provided with a screw blade 4c at the tip end, and a pair of forming rolls 4a, 4a rotated by an electric motor 4n through a loading port 1b by a screw feeder 4b rotated by an electric motor 4m. Are pressed continuously between them to form agglomerates 8.

  The number of rotations of the pair of forming rolls 4a, 4a and the number of rotations of the screw feeder 4b are controlled by controlling the motor 4m and the motor 4n in conjunction with the controller 4d in order to produce high-strength agglomerates with good yield. , Are appropriately maintained at the optimum values.

  However, in the screw blade 4c of the conventional molding machine shown in FIG. 2, the pitch difference d of the screw blade 4c is constant from the leading end (lower end in the figure) to the rear end (upper end in the figure) of the screw blade 4c. That is, the blade angle of the screw blade 4c with respect to the horizontal is constant from the front end to the rear end of the screw blade.

  According to the investigation by the present inventors, in a molding machine, when the blade angle of the screw blade with respect to the horizontal is constant from the leading end to the trailing end of the screw blade, (i) ) Voids in the agglomerate material increase, voids in the agglomerate increase, and (ii) adhesive force of the agglomerate material increases, pushing the agglomerate into a pair of forming rolls. The amount of raw material is not stable, and these things work together to reduce the strength and yield of the agglomerate.

  Then, based on the above knowledge, the present inventors increased the pitch difference between the screw blades provided at the leading end of the screw feeder continuously or stepwise from the leading end to the trailing end of the screw blade. That is, the blade angle of the screw blade with respect to the horizontal was increased continuously or stepwise from the leading end to the trailing end of the screw blade.

  FIG. 3 shows an embodiment of the molding machine of the present invention. In the numbers in FIG. 3, the same numbers as those in FIG. 2 indicate the same numbers as those in FIG.

  In the molding machine of the present invention shown in FIG. 3, two screw feeders 4b are arranged in the hopper 1a, but the number of screw feeders 4b may be appropriately set according to the capacity of the hopper 1a.

  In the molding machine of the present invention, the agglomerated raw material 3a charged into the hopper 1a from the charging port 1c and molded by the molding machine 4 is a mixed raw material obtained by mixing various raw materials. Need to be maintained. Therefore, the stirring plate 4y may be attached to the upper end of the screw feeder 4b (the portion above the screw blade 4z).

  Even when the stirring plate 4y is not attached, if the uniform mixing state of the agglomerated raw material can be maintained inside the hopper 1a, the stirring plate 4y is not attached.

  The pressure of the molding roll 4a of the molding machine 4 is constantly measured by the load cell 4f, and when the pressure needs to be adjusted, the pressure is adjusted by the hydraulic cylinder 4e.

  The width of the screw blade 4z increases from the leading end to the rear end of the screw blade. The pitch difference between the screw blades 4z provided at the leading end of the screw feeder 4b increases continuously or stepwise from the leading end (the lower end in FIG. 3) to the rear end (the upper end in FIG. 3).

  FIG. 4 shows one embodiment of the screw feeder used in the molding machine of the present invention. The pitch differences d1 and d2 of the screw blades 4z provided at the leading end of the screw feeder 4b increase continuously or stepwise from the leading end (the lower end in FIG. 4) to the rear end (the upper end in FIG. 4) ( d1 <d2).

  That is, the angles θ1, θ2, and θ3 with respect to the horizontal of the screw blade 4z increase continuously or stepwise from the front end (lower end) to the rear end (upper end) (θ1 <θ2 <θ3). In FIG. 4, θ3 is the blade angle at the rear end of the screw blade.

  Since the angle of the screw blade with respect to the horizontal is increased continuously or stepwise from the leading end to the trailing end, the agglomerated material caught in the screw blade is compressed while being pressed down toward the leading end of the screw blade. In addition, voids inside the agglomerated raw material are reduced, and the agglomerated raw material is densified.

  Then, the compacted agglomerate material is continuously pushed into the molding machine by a screw blade (see FIG. 3), but since the agglomerate material is densified, a pair of molding rolls of the molding machine are used. The amount of the agglomerated material to be pushed in between is stabilized, and the amount of the agglomerated material attached to the screw blades is reduced.

  The agglomerate material pressed between the pair of forming rolls is horizontally compressed by the rotating pair of forming rolls to form agglomerates (see FIG. 3, agglomerates 8). In the molding machine of the present invention, since the compacted agglomerate raw material is compressed to produce an agglomerate, a high-strength agglomerate having a low porosity can be produced with a high yield.

  Patent Literature 8 discloses a coal fuel pulverizing / supplying apparatus having a rotary screw therein and a coal feed pipe for feeding coal to a vertical mill, in which introduction of coal into the coal feed pipe is promoted, and the coal is supplied with blades. It is disclosed that the angle of the screw blade with respect to the horizontal is gradually reduced from the upper end to the lower end in order to prevent the lack of carbon by attaching to the surface.

  However, the action of the screw blades of the molding machine of the present invention is to produce a high-strength agglomerate having a low porosity with a good yield, by densifying the agglomerate material, and between a pair of rotating forming rolls. It is pushing in with a stable pushing amount, which promotes the action of the screw blade disclosed in Patent Document 8, that is, promotes coal feeding to a vertical mill for pulverizing coal, and coal adheres to the blade surface. Preventing a lack of carbon is technically different.

The present inventors investigated the blade angle of the screw blade which maximizes the effect of the screw blade of the molding machine of the present invention. As a result, the blade angle at the rear end of the screw blade is (angle of the blade at the tip of the screw blade) × 1.5 or more, (angle of the blade at the tip of the screw blade) × 2.6 or less, and preferably, (angle of the screw blade). It has been found that the blade angle at the tip of the screw blade) × 1.9 or more and the blade angle at the tip of the screw blade × 2.5 or less are suitable.

  When the blade angle at the rear end of the screw blade is less than (angle of the blade at the tip of the screw blade) × 1.5, the inclination of the screw blade is too gentle to compress the fine agglomerate raw material and obtain the desired denseness. It is difficult to densify. Therefore, the blade angle at the rear end of the screw blade is set to (the blade angle at the front end of the screw blade) × 1.5 or more. Preferably, (the blade angle at the tip of the screw blade) × 1.9 or more.

On the other hand, if the blade angle at the rear end of the screw blade exceeds (the blade angle at the tip of the screw blade) × 2.6, the inclination of the screw blade becomes too steep, and the compressed agglomerate material is removed from the screw blade. And the amount of the agglomerate to be pushed into the molding machine is not stable. Therefore, the blade angle at the rear end of the screw blade is set to (the blade angle at the front end of the screw blade) × 2.6 or less. It is preferably (the blade angle at the tip of the screw blade) × 2.5 or less.

  The blade angle at the tip of the screw blade is preferably 8 to 17 °. If the angle of the blade at the tip of the screw blade is less than 8 °, the force of the screw blade to push the agglomerate raw material between the pair of forming rolls rotating is insufficient. Therefore, the blade angle at the tip of the screw blade is preferably 8 ° or more. More preferably, it is 9 ° or more.

  On the other hand, when the blade angle at the tip of the screw blade exceeds 17 °, the force that the screw blade pushes between the pair of forming rolls that rotate the agglomerate material is too large, and the horizontal direction of the pair of rotating forming rolls is increased. It is difficult to maintain an equilibrium with the pressure. Therefore, the blade angle at the tip of the screw blade is preferably 17 ° or less. It is more preferably 16 ° or less.

  The action of the screw blades of the molding machine of the present invention is, as described above, in order to produce a high-strength agglomerate having a low porosity at a high yield, a compacted agglomerate raw material, and a pair of rotating forming rolls. During this time, it is necessary to push in with a stable pushing amount.

  The inventors of the present invention confirmed the performance of the conventional molding machine (see FIG. 2) and the performance of the present invention in order to confirm the above-mentioned operation and effect of the screw blade of the molding machine of the present invention (hereinafter sometimes referred to as “screw blade effect”). The performance of the molding machine (see FIGS. 3 and 4) was compared.

  In the conventional molding machine (see FIG. 2), the blade angle of the screw blade was set to θ1 = 10 °, and the pitch difference d was fixed. In the molding machine of the present invention (see FIGS. 3 and 4), the blade angles of the screw blades were increased stepwise by setting θ1 = 10 °, θ2 = 15 °, and θ3 = 22.5 °.

  When producing agglomerates with a molding machine, the number of rotations of the screw blades that push the agglomerate material between a pair of molding rolls and the number of rotations of the molding rolls that form the agglomerate material that is pushed into agglomerates There is a correlation between. First, the inventors of the present invention used a conventional molding machine (θ1 = 10 °) and a molding machine of the present invention (θ1 = 10 °, θ2 = 15 °, θ3 = 22.5 °) to obtain the rotation speed (rpm) of the screw blade. And the relationship between the number of revolutions (rpm) of the forming roll and the number of revolutions of the forming roll were investigated. The results are shown in FIG.

  When agglomerates are manufactured by a conventional molding machine (see ◇ in the figure), the rotation speed of the screw blade is limited to 52 rpm, and the rotation speed of the molding roll is limited to 4.2 rpm (R1 in the diagram). .

  On the other hand, when agglomerates are produced by the molding machine of the present invention (see □ in the figure), the conventional limit of the rotation speed of the screw blade: 40 rpm of 52 rpm or less, and the rotation speed of the forming roll is set to the conventional limit of 4.2 rpm. (R1 in the figure) can be increased to 4.7 rpm (R2 in the figure).

  This is presumed to be the result of the screw blade effect of the molding machine of the present invention greatly contributing to an increase in the rotation speed of the molding roll.

  If the number of revolutions of the forming roll increases, productivity of agglomerates improves. According to the investigation by the present inventors, the productivity (t / hr) of the molding machine of the present invention increased by about 5.2 t / hr from the conventional 36.0 t / hr.

  The present inventors further investigated the relationship between the porosity and the crushing strength of the agglomerate manufactured by the conventional molding machine and the agglomerate manufactured by the molding machine of the present invention in order to confirm the screw blade effect. The results are shown in FIG.

  In the agglomerate manufactured by the conventional molding machine, the porosity was approximately 29.1%, the crushing strength was 46 to 96 kgf, and the average was 78.2 kgf. The average porosity was 27.5%, and the average crushing strength was 102.5 kgf. In the agglomerate produced by the molding of the present invention, it was found that the average porosity decreased by 1.6% and the average crushing strength increased by 24.3 kgf.

  The crushing strength was defined as the strength at the time of cracking when a single dried briquette was laid on its side most stable and a load was applied from above (p in kg / p is an abbreviation of piece). is there). The yield was calculated by dividing the room volume of the sieved agglomerate by the mass of the manufactured agglomerate. The porosity was measured according to JIS 2205.

  Thus, the present inventors were able to confirm the screw blade effect of the molding machine of the present invention in terms of productivity and strength of agglomerates.

  Next, an example of the present invention will be described. The conditions in the example are one condition example adopted to confirm the operability and effects of the present invention, and the present invention is based on this one condition example. It is not limited. The present invention can adopt various conditions as long as the object of the present invention is achieved without departing from the gist of the present invention.

(Example)
A screw blade having a screw blade angle ratio of 1.0 to 2.7 is provided at the tip of the screw feeder of the molding machine to mold the agglomerated raw material under the raw material conditions shown in Table 1 and to form the raw material at the outlet side of the screw feeder. The yield of the agglomerate was measured. The results are shown in FIG.

When the screw blade angle ratio is 1.5 to 2.6, the agglomerate yield is 80% or more, and when the angle ratio is 1.9 to 2.55 , the agglomerate yield is 85% or more. I understand that there is. When the molding machine of the present invention is used, the agglomerate material can be appropriately compressed by the screw blade, the crushing strength of the agglomerate material is improved, and the yield of the agglomerate is significantly increased. I understand. As a result, the productivity of the molding machine is significantly improved.

  As described above, according to the present invention, the agglomerates to be charged into the rotary hearth-type reduction furnace and placed on the hearth can be manufactured with high strength and with good yield. The properties are significantly improved. Therefore, the present invention has high industrial applicability.

DESCRIPTION OF SYMBOLS 1, 1a Hopper 1b Loading inlet 1c Input port 2 Crusher 3 Kneader 3a Agglomerated raw material 4 Molding machine 4a Forming roll 4b Screw feeder 4c Screw blade 4d Controller 4e Hydraulic cylinder 4f Load cell 4m, 4n Motor 4y Stir plate 4z Screw blades 5 Dryer 6 Charging device 7 Charging part 8 Agglomerate 9 Discharge device 10 Rotating hearth type reduction furnace 11 Burner 12 Exhaust gas pipe d1, d2 Pitch difference θ1, θ2, θ3 Angle

Claims (2)

In a molding machine in which the agglomerated raw material containing the iron oxide-containing substance and the carbonaceous reducing substance is pressed between a pair of molding rolls with one or more screw feeders,
(I) The blade angle of the screw blade provided at the leading end of the screw feeder increases continuously or stepwise from the leading end to the trailing end, and
(Ii) Molding characterized in that the blade angle at the rear end of the screw blade is (the blade angle at the tip of the screw blade) × 1.9 or more and (the blade angle at the tip of the screw blade) × 2.5 or less. Machine.   The molding machine according to claim 1, wherein a width of the screw blade increases from a front end to a rear end of the screw blade.

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