JP2017039969A - Method of charging raw material into blast furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To segregate and charge a coarse-grained blast furnace raw material into the center of a bell-less blast furnace including a center feed type raw material charging device having an upper bunker and a lower bunker, without installing a segregation control plate in the lower bunker.SOLUTION: When a blast furnace raw material is charged into a bell-less blast furnace 1 using a raw material charging device 2 comprising an upper bunker 5, a lower bunker 9, a raw material storage tank 3A, a rotary introduction chute 6, and a rotary charging chute 11, a segregation state of coarse grains and fine grains of the blast furnace raw material deposited inside the raw material storage tank is controlled by a segregation control plate 13 installed in the raw material storage tank and a falling position of the blast furnace raw material from the rotary introduction chute is controlled at the time of charging the blast furnace raw material into the upper bunker to control the segregation of the coarse grains and fine grains of the blast furnace material deposited on the upper bunker, and after the blast furnace raw material is transferred from the upper bunker to the lower bunker, the blast furnace raw material deposited inside the lower bunker is charged into the blast furnace while rotating the rotary charging chute.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a raw material charging method to a bell-less blast furnace having a center feed type furnace top raw material charging device in which raw material bunkers (hoppers) are arranged in two stages, and in particular, a coarse blast furnace at the center of the blast furnace. The present invention relates to a raw material charging method in which raw materials can be segregated and charged.

  In blast furnace operation, iron ore (also referred to as “ore”) and coke are usually charged from the top of the furnace so that they are alternately layered to form an ore layer and a coke layer. In addition, for the purpose of improving the coke utilization rate, the mixed raw material in which coke is mixed in the ore in advance and the coke are alternately charged to form a coke mixed ore layer and a coke layer in layers. Yes.

In this blast furnace operation, from the viewpoint of reducing CO ₂ emissions and saving resources, operation with a low reducing material ratio (total amount of coke and injected fuel charged from the top of the furnace per ton of hot metal produced) As a technology for that purpose, improvement of gas utilization rate and heat loss reduction technology are being implemented. Specifically, instead of charging the blast furnace raw material uniformly into the blast furnace, a technology is implemented to control the distribution in the blast furnace, especially the particle size distribution in the blast furnace radial direction, such as ore and coke. ing.

  For example, in Patent Document 1, when a blast furnace raw material temporarily stored in a raw material bunker (also referred to as “furnace top bunker”) is charged into a blast furnace through a turning chute provided below the top bunker. A movable plate that can be tilted is provided in the furnace top bunker, the blast furnace raw material charged into the furnace top bunker is collided with the movable plate, the dropping direction is changed, and the blast furnace raw material deposited in the furnace top bunker is The blast furnace raw material layer is placed in the blast furnace in the order of fine particles, medium particles, coarse particles, or coarse particles, medium particles, fine particles in that order, and discharged according to the segregated particle size. A raw material charging method to be formed has been proposed.

  According to Patent Document 1, blast furnace raw materials can be discharged from the top bunker in the order of coarse particles, medium particles, fine particles, or vice versa. Depending on the tilting direction of the turning chute, the direction in which the tip of the turning chute moves (tilts) from the peripheral side of the blast furnace (referred to as “forward tilting”), or the opposite direction (“reverse tilting”). It is said that coarse grains can be deposited in the center of the blast furnace.

  Further, in Patent Document 2, a segregation control plate capable of adjusting an inclination angle for changing a falling direction of a blast furnace raw material charged into the furnace top bunker is provided at an upper portion in the furnace top bunker, and the ore and coke are provided. During the charging of the mixed raw material into the furnace top bunker, the inclination angle of the segregation control plate is changed from the first inclined angle at which the mixed raw material falls to the position directly above the outlet of the furnace top bunker. Switch to the second tilt angle where the drop position of the side wall is horizontally away from the position directly above the discharge port, and the coke in the mixed raw material segregates in the furnace top bunker at a position far from the discharge port of the furnace top bunker. The mixed raw material deposited in this manner is discharged from the discharge port of the furnace top bunker, so that the coke mixing ratio in the mixed raw material is gradually increased from the initial discharge stage to the late discharge stage. Formed in the blast furnace Is the coke mixed ore layer material charging method to segregate to the top of the layer of coke has been proposed.

According to Patent Document 2, it is possible to increase the ore reduction efficiency by segregating the coke upward in the coke mixed ore layer, enabling efficient blast furnace operation and improving the ore reduction efficiency. Because the amount of coke used can be reduced by this, the amount of CO ₂ generated can be reduced.

  In addition, since the blast furnace raw material deposited in the top bunker is discharged from what is deposited immediately above the discharge port, the blast furnace raw material segregated at a position far from the discharge port of the top bunker is discharged at the beginning of discharge. Therefore, it is possible to control the charging of raw materials as in Patent Document 1 and Patent Document 2.

  By the way, as a raw material charging device to a blast furnace, a bellless charging device is widely adopted, and the bellless charging device includes a parallel bunker type raw material charging device in which a raw material bunker at the top of the furnace is installed in parallel (patent Documents 1 and 2) and a center feed type material charging device (see Patent Documents 3 and 4) in which the material bunker is installed in the upper and lower two stages exist. Generally, the center feed type raw material charging device is structurally simple compared to the parallel bunker type raw material charging device, so the capital investment is low, and when charging the charged material into the furnace. There is an advantage that the distribution in the circumferential direction is small and can be distributed almost uniformly.

  In a blast furnace having a parallel bunker-type raw material charging apparatus that is currently the world's mainstream (also referred to as “parallel bunker type blast furnace”), as shown in Patent Document 1 and Patent Document 2, segregation control is performed inside each bunker. A technology (segregation control technology) for forcibly segregating blast furnace raw materials by installing a plate has already been implemented. However, in a blast furnace having a center feed type raw material charging device (also referred to as “center feed type blast furnace”), a technique for forcibly segregating the blast furnace raw material is not applied.

  In the center-feed type blast furnace, when a segregation control plate is installed in a raw material bunker (referred to as “lower bunker”) directly above the blast furnace, a raw material bunker installed on the upper part of the segregation control plate is inspected and maintained. It is necessary to remove (referred to as “upper bunker”), and there is a problem that inspection and maintenance of the segregation control plate are not in time within the limited repair time.

  In addition, if a segregation control plate is installed in the upper bunker, a segregation effect will occur in the blast furnace raw material inside the upper bunker, but it will form in the upper bunker when the segregated blast furnace raw material passes through the lower bunker directly below it. There is a problem that the segregation effect of the bent corners is reduced.

  For the above two reasons, in the center feed type blast furnace, it is difficult to put the segregated blast furnace raw material into the blast furnace. Conventionally, the technology for forcibly segregating the blast furnace raw material (segregation control technology) It was not applied to the center feed blast furnace.

JP 2008-179899 A JP 2013-95970 A JP 2014-1111819 A JP 2014-162989 A

  The present invention has been made in view of the above circumstances, and an object thereof is to install a segregation control plate in a lower bunker in a bellless blast furnace having a center feed type raw material charging device having an upper bunker and a lower bunker. The raw blast furnace raw material charging method can control the coarse and fine particles of the blast furnace raw material discharged from the lower bunker and thereby segregate and charge the coarse blast furnace raw material into the center of the blast furnace. Is to provide.

  The inventors of the present invention have studied and studied to solve the above problems. As a result, in the bell-less blast furnace having the center feed type raw material charging device, the segregation of the blast furnace raw material is controlled step by step in the raw material storage tank and the upper bunker for supplying the blast furnace raw material to the upper bunker. It has been found that coarse blast furnace raw material can be segregated in the center and charged.

  That is, the segregation control plate is installed in the raw material storage tank for supplying the blast furnace raw material to the upper bunker, and first, the coarse and fine segregation of the blast furnace raw material deposited in the raw material storage tank is controlled. In the bunker, segregation of coarse and fine grains of blast furnace raw material deposited in the upper bunker is adjusted by adjusting the drop position of the blast furnace raw material supplied from the raw material storage tank and introduced into the upper bunker via the swivel charging chute. This controls the segregation of coarse and fine grains even in the blast furnace raw material transferred to the lower bunker and deposits, that is, the coarse and fine grains of the blast furnace raw material discharged from the lower bunker are controlled. It has been found that coarse blast furnace raw material can be segregated and charged in the center of the blast furnace.

The present invention has been made based on the above findings, and the gist thereof is as follows.
[1] An upper bunker and a lower bunker, which are arranged in two stages at the top of the bellless blast furnace top and connected by a plurality of ports, a segregation control plate is installed in the upper part, and a raw material storage tank opening / closing gate is installed in the lower part A raw material storage tank for accumulating and containing blast furnace raw material that is collided with the segregation control plate, a raw material charging conveyor for conveying the blast furnace raw material discharged from the raw material storage tank to the upper bunker, and the raw material A swivel charging chute for charging the blast furnace raw material conveyed by the charging conveyor into the upper bunker, a plurality of port opening / closing gates for opening / closing the plurality of ports, and a lower end of the lower bunker are deposited in the lower bunker. And a lower bunker opening / closing gate for discharging the blast furnace raw material, and a swing charging chute for charging the blast furnace raw material discharged from the lower bunker into the blast furnace. A method for charging a blast furnace in bell-less blast furnace using over-fed material charging device,
When the blast furnace raw material is charged into the raw material storage tank, the blast furnace raw material collides with the segregation control plate to control the flow direction and the deposition shape of the blast furnace raw material, so that coarse particles of the blast furnace raw material deposited inside the raw material storage tank and When the blast furnace raw material is charged into the upper bunker by controlling the segregation state of fine grains, the blast furnace raw material falls from the swirl charging chute to be deposited inside the plurality of ports of the upper bunker. Control the segregation state of coarse and fine blast furnace raw materials,
Next, the plurality of port opening / closing gates are switched from the closed state to the open state, and the blast furnace raw material accumulated in the plurality of ports of the upper bunker is transferred from the upper bunker to the lower bunker, and then the lower bunker opening / closing gate is closed. The blast furnace raw material charging method is characterized in that the blast furnace raw material deposited in the lower bunker by switching from the open state to the open state is charged into the blast furnace while rotating the swirl charging chute.
[2] The blast furnace raw material discharged from the lower bunker is disposed inside the plurality of ports of the blast furnace raw material and the upper bunker so that the initial discharge is coarse and the final discharge is fine. Control the segregation state of coarse and fine grains of the blast furnace raw material to be deposited, and swirl the swirl charging chute so that the tip of the swirl charging chute moves from the center of the blast furnace toward the peripheral side, The raw material charging method to the blast furnace according to the above [1], wherein coarse blast furnace raw material is deposited in the center of the blast furnace.

  According to the present invention, when charging the blast furnace raw material into the blast furnace using the center feed type raw material charging device, first, the raw material storage tank disposed upstream of the upper bunker is deposited in the raw material storage tank. Control segregation of coarse and fine blast furnace raw materials, and then maintain segregation of coarse and fine blast furnace raw materials in raw material storage tanks with controlled segregation of coarse and fine grains Therefore, segregation of coarse and fine grains is maintained even in the blast furnace raw material deposited on the lower bunker transferred from the upper bunker. Thus, segregation control is performed on the lower bunker in the center feed blast furnace. Without carrying out the above, it is possible to put the segregated blast furnace raw material into the blast furnace, that is, to charge the coarse blast furnace raw material in the center of the blast furnace. As a result, an industrially beneficial effect is achieved in that the air permeability and combustion efficiency of the blast furnace center can be improved.

It is a schematic sectional drawing which shows an example of the bell-less blast furnace provided with the center feed type raw material charging device used when implementing this invention. It is the schematic by the X-X 'arrow of FIG. It is a figure which compares and shows the target particle size of the blast furnace raw material discharged | emitted from a lower bunker by reverse tilting and forward tilting. It is the outline | summary which shows the investigation result of the segregation in the ore deposit layer in the raw material storage tank in the shape of the segregation control board in case 1, the installation method of the segregation control board, and the raw material storage tank at that time. It is a schematic diagram which shows the investigation result of the segregation in the ore deposit layer in the shape of the segregation control board in case 2, the installation method of the segregation control board, and the raw material storage tank at that time. It is a schematic diagram which shows the investigation result of the segregation in the ore accumulation layer in the shape of the segregation control board in case 3, the installation method of the segregation control board, and the raw material storage tank at that time. It is a figure which compares and shows the result of having investigated the particle size change of the ore discharged | emitted from a raw material storage tank in time series. It is a figure which shows the fall position of the blast furnace raw material from the turning throwing chute in case 4, and the form of the segregation of the coarse grain and fine grain in an upper bunker at that time. It is a figure which shows the fall position of the blast furnace raw material from the turning throwing chute in case 5, and the form of the segregation of the coarse grain and fine grain in an upper bunker at that time. It is a figure which shows the fall position of the blast furnace raw material from the turning throwing chute in case 6, and the form of the segregation of the coarse grain and fine grain in an upper bunker at that time. It is a figure which compares and shows the result of having investigated the particle size change of the ore discharged | emitted from a lower bunker in time series. It is a figure which compares and shows the calculation result of the pressure loss in a furnace with the case where the conventional segregation control board is not, and the case of Case 5. It is a figure which compares and shows the calculation result of a gas utilization factor in the case of the case where the conventional segregation control board is not provided, and the case of Case 5.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a schematic cross-sectional view showing an example of a bell-less blast furnace equipped with a center-feed type raw material charging device used in carrying out the present invention, and FIG. 2 is a schematic view taken along arrow XX ′ of FIG. It is.

  As shown in FIGS. 1 and 2, the center feed type raw material charging apparatus 2 includes an upper bunker 5 and a lower bunker 9, and the upper bunker 5 and the lower bunker 9 are arranged in two stages at the top of the bellless blast furnace 1. Has been placed. At the upper part of the upper bunker 5, a turning charging chute 6 for introducing a blast furnace raw material (not shown) into the upper bunker 5 is installed, and the lower part of the upper bunker 5 is connected via the turning charging chute 6. The port is divided into four ports 7A, 7B, 7C, 7D for depositing the charged blast furnace raw material and transferring the deposited blast furnace raw material to the lower bunker 9. The ports 7A to 7D are arranged concentrically and aligned in the horizontal direction, and port opening / closing gates 8A, 8B, 8C, and 8D for opening and closing each port are installed at the lower ends of the ports 7A to 7D. . In the lower bunker 9, positions corresponding to the respective ports 7A to 7D are opened, and the upper bunker 5 and the lower bunker 9 are connected via the ports 7A to 7D. Although the upper bunker 5 shown in FIG. 1 has four ports, there is no problem if the number of installed ports is two or more. The blast furnace raw material is iron ore, coke, or a mixture of coke and iron ore.

  A lower bunker opening / closing gate 10 for discharging the blast furnace raw material deposited in the lower bunker is installed at the lower end of the lower bunker 9, and the blast furnace raw material discharged from the lower bunker 9 is disposed below the lower bunker opening / closing gate 10. A turning charging chute 11 for charging into the blast furnace is installed. The swivel charging chute 11 is provided inside the top of the bellless blast furnace 1. The swirl charging chute 11 is swung while the tip of the swirl charging chute 11 is moved (tilted) from the peripheral side of the bell-less blast furnace 1 to charge the blast furnace raw material (forward tilting). Forming the surface of the blast furnace raw material in a mortar shape also means that the tip of the swirl charging chute 11 is swung while moving (tilting) from the center of the bellless blast furnace 1 to the peripheral side, and the blast furnace raw material is charged ( It is configured so that both can be formed in the shape of a mortar.

  In addition, when depositing blast furnace raw material in the furnace, the reverse tilting method of depositing blast furnace raw material from the center side, that is, from the lower side of the mortar-shaped slope, is more Since there is no phenomenon such as collapse of the accumulated blast furnace raw material and the desired accumulation shape is obtained, it is considered that reverse tilting is more preferable than the forward tilting in which the blast furnace raw material is rolled up from the upper side.

  On the other hand, on the upstream side of the upper bunker 5, the blast furnace raw material cut out from the raw material tank (not shown) for storing the blast furnace raw material and transported by the raw material transport conveyor (not shown) is deposited and temporarily stored. Raw material storage tanks 3A and 3B are installed. The blast furnace raw material transferred by the raw material transfer conveyor is input to the raw material storage tanks 3A and 3B via the raw material storage tank input chute 12.

  The raw material storage tanks 3A and 3B are provided with a segregation control plate 13 in the upper part, and the blast furnace raw material charged through the raw material storage tank charging chute 12 collides with the segregation control plate 13, and then the raw material storage tank. Deposit on 3A, 3B. Raw material storage tank open / close gates 14A and 14B are respectively installed below the raw material storage tanks 3A and 3B. By opening the raw material storage tank open / close gates 14A and 14B, the raw material storage tanks 3A and 3B are deposited on the raw material storage tanks 3A and 3B. The blast furnace raw material that has been dropped falls on the raw material charging conveyor 4 below the raw material storage tank opening / closing gates 14A and 14B, and is conveyed via the raw material charging conveyor 4 to the swirl charging chute 6 above the upper bunker 5. It is configured. In FIG. 1, reference numeral 15 is a coke mixed ore layer, and 16 is a coke layer.

  Using the center-feed type raw material charging device 2 configured in this way, the raw material of the blast furnace is charged into the furnace by segregating coarse particles and fine particles with a blast furnace raw material in one charge, and the center of the bell-less blast furnace 1 The segregation of coarse blast furnace raw material in the part was studied.

  At that time, as a precondition, the swirl charging chute 11 is reversely tilted to charge the blast furnace raw material by swiveling while moving the tip of the swirl charging chute 11 from the center of the bell-less blast furnace 1 to the peripheral side. . In the case of reverse tilting, the blast furnace raw material discharged from the swirl charging chute 11 is accumulated in the lower bunker 9 so that the initial discharge is coarse and the final discharge is fine as shown in FIG. It is necessary to control the segregation state of the raw material. That is, the blast furnace raw material deposited on the lower bunker 9 is coarsely deposited so that the coarse blast furnace raw material is deposited on the lower side and the center side in the early discharge order, and the fine blast furnace raw material is deposited on the side wall side in the lower discharge order. It is necessary to control the segregation of fine grains. When the method of charging the blast furnace raw material from the swirl charging chute 11 is forward tilting, as shown in FIG. 3, unlike the case of reverse tilting, the initial discharge is fine and the final discharge is coarse. It is necessary to control the segregation state of the blast furnace raw material deposited on the lower bunker 9 so as to form grains. Here, FIG. 3 is a diagram showing the target particle size of the blast furnace raw material discharged from the lower bunker in comparison with reverse tilting and forward tilting, and the ore dimensionless harmonic mean diameter on the vertical axis is the discharge It is defined as the relative particle size value when the average value of the particle size is 1.0, and the dimensionless discharge time on the horizontal axis is the discharge displayed using the time from the start of discharge from the lower bunker to the end of discharge as the denominator. It's time.

  Further, as a further precondition, the four port opening / closing gates 8A, 8B, 8C, 8D of the upper bunker 5 are opened simultaneously, and the blast furnace raw material deposited on the four ports 7A, 7B, 7C, 7D is simultaneously opened to the lower bunker 9 It was decided to be transferred to. In this case, in the four ports 7A, 7B, 7C, and 7D, the segregation of coarse grains and fine grains of the blast furnace raw material deposited in each port may be controlled under the same conditions. Moreover, the raw material storage tank opening / closing gate 14A below the raw material storage tank 3A and the raw material storage tank opening / closing gate 14B below the raw material storage tank 3B are opened simultaneously, and the blast furnace raw material deposited in the raw material storage tank 3A and the raw material storage tank 3B is simultaneously released. It was decided to put it in the upper bunker 5. By doing in this way, in the raw material storage tank 3A and the raw material storage tank 3B, the segregation of coarse grains and fine grains of the blast furnace raw material to be deposited may be controlled under the same conditions.

  Under these conditions, iron ore was used as the blast furnace raw material, and the test was carried out using the center feed type raw material charging device 2 of 1/18 scale of the actual machine.

  First, the segregation control plate 13 was installed in the raw material storage tank 3A, and a test was conducted to investigate the segregation state of coarse grains and fine grains in the raw material storage tank 3A at that time. 4, 5, and 6, the shape of the segregation control plate 13 installed in the raw material storage tank 3 </ b> A, the installation method of the segregation control plate 13, and the coarse particles in the ore deposit layer 17 in the raw material storage tank at that time And the investigation result of the form of fine grain segregation is shown. In the test, the segregation control plate 13 was installed so that the center of the segregation control plate 13 and the center of the raw material storage tank 3A were substantially at the same position. 4 to 6, large spheres in the ore deposit layer 17 represent coarse grains, and small spheres represent fine grains.

  FIG. 4 uses a triangular columnar segregation control plate 13 whose section is an isosceles triangle, the surface formed by the base of the isosceles triangle is the bottom surface, and the load flow direction of the ore is continuous at the apex of the isosceles triangle. It is the schematic of the test (case 1) which has arrange | positioned the triangular-column-shaped segregation control board 13 in the raw material storage tank 3A so that it may become a direction parallel to the side of the triangular prism formed in this way. As shown in FIG. 4, in case 1, coarse ore is segregated along the center line of the cross section of the raw material storage tank 3A by the segregation control plate 13, and fine ore is formed on the side wall side of the raw material storage tank 3A. Segregated.

  FIG. 5 uses a triangular columnar segregation control plate 13 whose section is an isosceles triangle, the surface formed by the base of the isosceles triangle is the bottom surface, and the load flow direction of the ore is continuous at the apex of the isosceles triangle. It is a schematic diagram of a test (case 2) in which a triangular columnar segregation control plate 13 is arranged so as to be in a direction orthogonal to the sides of the triangular column formed in the above. As shown in FIG. 5, in Case 2, coarse ore is segregated along the center line of the cross section of the raw material storage tank 3A by the segregation control plate 13, and fine ore is formed on the side wall side of the raw material storage tank 3A. Segregated. However, when Case 1 and Case 2 are compared, the segregation direction of coarse ore in the raw material storage tank 3A is different.

  FIG. 6 uses a quadrangular pyramid-shaped segregation control plate 13, the bottom surface of the quadrangular pyramid is the bottom surface, and the load flow direction of the ore passes through the apex of the quadrangular pyramid and is parallel to the side forming the bottom surface of the quadrangular pyramid. It is a schematic diagram of a test (case 3) in which a triangular prism-type segregation control plate 13 is arranged. As shown in FIG. 6, in case 3, the coarse ore was segregated at the center of the raw material storage tank 3A by the segregation control plate 13, and fine ore was segregated on all side walls of the raw material storage tank 3A. .

  FIG. 7 shows the results of a time-series change in the ore particle diameter when the ore deposit layer 17 deposited in the raw material storage tank 3A under the conditions of cases 1 to 3 is discharged from the raw material storage tank 3A. In FIG. 7, for the purpose of comparison, the results of investigation of time-series changes in ore particle diameter investigated when discharging the ore deposit layer 17 deposited under the condition where no segregation control plate is installed from the raw material storage tank 3A. Is also shown.

  As shown in FIG. 7, in cases 1, 2, and 3, the ore particle size is relatively large at the initial stage of discharge from the raw material storage tank 3A, and the ore particle size is relatively small as discharge progresses. It was confirmed that That is, by installing a triangular columnar or quadrangular pyramid-shaped segregation control plate 13 on the upper part of the raw material storage tank 3A, the blast furnace raw material is made to collide with the segregation control plate 13 and put into the raw material storage tank 3A. However, it was confirmed that segregation of the blast furnace raw material, which was coarse and fine at the end of discharge, was formed.

  In contrast, when the segregation control plate 13 is not installed, the tendency is that the initial stage of discharge is fine and the final stage of discharge is coarse, but the separation between the coarse and fine is not stable. It was found that the desired segregation state could not be obtained.

  The inventors further conducted a test to investigate the relationship between the ore dropping position from the turning throw chute 6 to the upper bunker 5 and the segregation state of coarse grains and fine grains in the upper bunker. The change of the ore dropping position from the turning throwing chute 6 to the upper bunker 5 was adjusted by installing the stabilizer 18 on the turning throwing chute 6 or installing the extension pipe 19 on the turning throwing chute 6. The stabilizer 18 is for dropping ore on the center of the upper bunker 5, and the extending pipe 19 is for dropping ore on the side wall side of the upper bunker 5.

  In this case, the normal drop position (position 2R / 5 to 5R / 5 away from the center of the upper bunker 5; R is a radius from the center of the upper bunker 5 to the inner surface of the side wall), that is, the drop position is designated as the port opening / closing gate 8A. , 8B, 8C, 8D, when the fall position is set to the center side of the upper bunker 5 by the stabilizer 18 (position R / 6 to R / 4 away from the center of the upper bunker 5). And it changed into 2 levels in the case of making it into the side wall side (position distant 4R / 5-R from the center of the upper bunker 5) by the extending pipe 19 at the side wall side of the upper bunker 5. Note that a normal drop position test is referred to as case 4, a drop position is referred to as case 5 on the center side of the upper bunker 5, and a drop position is referred to as case 6 on the side wall side of the upper bunker 5.

  8, 9, and 10, the swirl charging chute 6 is continuously swirled (swivel speed: 54 rpm) under the condition that the method of charging the ore into the raw material storage tank 3 </ b> A is Case 1 (triangular segregation control plate—parallel direction). The ore deposits in the upper bunker when the ore cut out from the raw material storage tank 3A is put into the upper bunker 5 through the swiveling throw chute 6 under the conditions of cases 4, 5, and 6, respectively. The investigation result of the form of coarse and fine segregation in 17 is shown. 8 shows the result in case 4, FIG. 9 shows the result in case 5, and FIG. 10 shows the result in case 6. Moreover, in FIGS. 8-10, the big sphere in the ore deposit layer 17 represents a coarse grain, and the small sphere represents a fine grain.

  As shown in FIG. 8, in the case 4 (falling position; a position directly above the port opening / closing gate), coarse particles segregate at the center and the side wall of the upper bunker 5, and each port 7A, 7B, 7C, 7D Fine particles segregated in the center. 8 to 10 show the discharge order in the ore deposit layer 17 deposited on the port 7A based on past experience and investigation, that is, sequentially cut out from the blast furnace raw material deposited at the center of the port 7A. From the viewpoint of discharging coarse particles at the initial stage of discharge from the ports 7A, 7B, 7C, and 7D, the case 4 cannot be said to be a desirable segregation form.

  As shown in FIG. 9, in case 5 (falling position; the center side of the upper bunker 5), coarse particles segregated at the center of each port 7 </ b> A, 7 </ b> B, 7 </ b> C, 7 </ b> D and the side wall of the upper bunker 5. From the viewpoint of discharging coarse particles at the initial discharge from the ports 7A, 7B, 7C, and 7D, the case 5 is a preferable segregation form as compared with the case 4.

  As shown in FIG. 10, in case 6 (falling position; side wall side of upper bunker 5), coarse particles segregate at the center of upper bunker 5, and at the center of each port 7A, 7B, 7C, 7D. Fine grains segregated. From the viewpoint of discharging coarse particles at the initial discharge from the ports 7A, 7B, 7C, and 7D, the case 6 is the most undesirable segregation form among the cases 4 to 6.

  In addition, when putting a powder and forming a deposition layer, the accumulation layer of the raised powder is formed in a fall position, and a slope is formed in the circumference | surroundings. When there is a difference in the particle size of the powder to be charged, a phenomenon occurs in which the powder having a large particle size segregates on the outer peripheral portion of the slope. The segregation of coarse grains and fine grains in the raw material storage tank 3A and the upper bunker 5 described above is based on this phenomenon.

  In FIG. 11, the ore deposit layer 17 deposited on the upper bunker 5 under the conditions of cases 4 to 6 is transferred to the lower bunker 9, and the ore deposit layer 17 transferred to the lower bunker 9 is discharged from the lower bunker 9. The investigation result of the time-series change of particle diameter is shown. In FIG. 11, for comparison, the segregation control plate 13 is not installed in the raw material storage tank 3A, and the ore particle size under the condition that ore is charged from the swivel charging chute 6 to a position directly above the port opening / closing gate is shown. The survey results of time series changes are also shown.

  When charging the blast furnace raw material by reverse tilting using the swirl charging chute 11, as shown in FIG. 11, the time-series change of the ore particle size in case 5 is the target particle size (see FIG. 3). Therefore, it was found that by adopting the case 5, coarse particles can be segregated in the center of the bell-less blast furnace 1. On the other hand, it was found that when the case 4, the case 6 and the segregation control plate 13 are not installed, it is insufficient to segregate coarse particles at the center of the bell-less blast furnace 1.

  That is, the segregation control plate 13 is installed in the raw material storage tank 3A to control the segregation of coarse and fine particles of the blast furnace raw material deposited in the raw material storage tank 3A, and is supplied to the upper bunker 5 through the swivel charging chute 6. It was confirmed that coarse grains could be segregated at the center of the bell-less blast furnace 1 by controlling the dropping position of the blast furnace raw material. The method of installing the segregation control plate 13 in the raw material storage tank 3A is effective not only for the case 1 but also for the cases 2 and 3.

  FIG. 12 shows the case without the conventional segregation control plate (the segregation control plate 13 is not installed in the raw material storage tank 3A and the ore is fed from the swiveling throw chute 6 to a position directly above the port opening / closing gate). The calculation result of the pressure loss in the furnace performed in the case is shown in comparison. By applying Case 5, it was found that the central flow strengthening due to the grain size expansion of the blast furnace raw material on the blast furnace center side improved the furnace air permeability and reduced the furnace pressure loss by about 1.5 kPa.

  FIG. 13 shows the calculation result of the gas utilization rate when the distribution control for suppressing the gas flow is directed until the pressure loss in the furnace becomes equal to that in the case without the segregation control plate in the case 5. Compared with the case without segregation control plate. It has been found that application of Case 5 can improve the gas utilization rate by about 0.2%.

  In addition, although the said description is a case where the turning charging chute 11 is reverse-tilting, even if the turning charging chute 11 is forward-tilting, the present invention is applied to the central portion of the bell-less blast furnace 1. Coarse grains can be segregated.

  In this case, as shown in FIG. 3, the blast furnace raw material discharged from the lower bunker 9 needs to be fine in the initial stage of discharge and coarse in the final stage of discharge. Therefore, in the raw material storage tank 3A, it is necessary to control segregation so that fine particles are segregated on the center side of the raw material storage tank 3A and coarse particles are segregated on the side wall side of the raw material storage tank 3A. This is realized by using a sieve having an opening size through which fine particles of the blast furnace raw material pass but coarse particles do not pass as the segregation control plate 13 installed in the raw material storage tank 3A. The fine particles pass through the sieve and segregate in the center of the raw material storage tank 3A, and the coarse particles do not pass through the sieve and segregate on the side wall side of the raw material storage tank 3A. In the subsequent upper bunker 5, coarse particles are segregated to the center side of the upper bunker 5 with the dropping position of the blast furnace raw material charged into the upper bunker 5 as the side wall side of the upper bunker 5 as shown in FIG. 10. By controlling the segregation in this way, the blast furnace raw material discharged from the lower bunker 9 is fine in the initial discharge and coarse in the final discharge.

  In the bell-less blast furnace 1 provided with the center feed type raw material charging apparatus 2 shown in FIG. 1, the present invention is applied when the coke mixed ore layer 15 and the coke layer 16 are formed in layers. In the raw material storage tank 3A, a triangular columnar segregation control plate 13 whose section is an isosceles triangle is used, and the load direction of the ore to the raw material storage tank 3A is the direction of the apex formed by the apex angle of the isosceles triangle The segregation control plate 13 was disposed so as to be in a direction perpendicular to the direction (see FIG. 5).

  In addition, a stabilizer 18 is installed at the tip of the turning throwing chute 6 so that the blast furnace raw material dropping position on the upper bunker 5 is R / 5 away from the center of the upper bunker 5 and is turned at a turning speed of 54 rpm. Blast furnace raw material was put into the upper bunker 5. Thereafter, the blast furnace raw material accumulated in the upper bunker 5 was transferred to the lower bunker 9, and the swirl charging chute 11 was reversely tilted to charge the blast furnace raw material in the lower bunker into the bell-less blast furnace.

  As a result of continuing this operation, the conventional operation method (operation in which the segregation control plate 13 is not installed in the raw material storage tank 3A, and ore is input from the swiveling input chute 6 directly above the port opening / closing gate) In comparison with the above, the reducing material ratio (the total amount of coke and injected fuel charged from the top of the furnace per ton of hot metal produced) was reduced by 1.2 kg / ton.

DESCRIPTION OF SYMBOLS 1 Berles blast furnace 2 Center feed type raw material charging device 3A, 3B Raw material storage tank 4 Raw material charging conveyor 5 Upper bunker 6 Turning throw chute 7A, 7B, 7C, 7D Port 8A, 8B, 8C, 8D Port open / close gate 9 Lower bunker DESCRIPTION OF SYMBOLS 10 Lower bunker opening / closing gate 11 Turning charging chute 12 Raw material storage tank charging chute 13 Segregation control board 14A, 14B Raw material storage tank opening / closing gate 15 Coke mixed ore layer 16 Coke layer 17 Ore deposit layer 18 Stabilizer 19 Extension pipe

Claims (2)

The segregation, which is arranged in two stages at the top of the bellless blast furnace top and connected by a plurality of ports, and a segregation control plate is installed at the top and a raw material storage tank opening / closing gate is installed at the bottom A raw material storage tank for accumulating and storing blast furnace raw material that is introduced by colliding with the control plate, a raw material charging conveyor for conveying the blast furnace raw material discharged from the raw material storage tank to the upper bunker, and the raw material charging conveyor A blast furnace raw material that is provided at a lower end of the lower bunker and is deposited in the lower bunker, a swivel charging chute that inputs the blast furnace raw material conveyed in the upper bunker, a plurality of port opening and closing gates that open and close the plurality of ports A center bun that includes a lower bunker opening / closing gate for discharging the blast furnace and a turning charging chute for charging the blast furnace raw material discharged from the lower bunker into the blast furnace. A method for charging a blast furnace in bell-less blast furnace using over de type raw material charging device,
When the blast furnace raw material is charged into the raw material storage tank, the blast furnace raw material collides with the segregation control plate to control the flow direction and the deposition shape of the blast furnace raw material, so that coarse particles of the blast furnace raw material deposited inside the raw material storage tank and When the blast furnace raw material is charged into the upper bunker by controlling the segregation state of fine grains, the blast furnace raw material falls from the swirl charging chute to be deposited inside the plurality of ports of the upper bunker. Control the segregation state of coarse and fine blast furnace raw materials,
Next, the plurality of port opening / closing gates are switched from the closed state to the open state, and the blast furnace raw material accumulated in the plurality of ports of the upper bunker is transferred from the upper bunker to the lower bunker, and then the lower bunker opening / closing gate is closed. The blast furnace raw material charging method is characterized in that the blast furnace raw material deposited in the lower bunker by switching from the open state to the open state is charged into the blast furnace while rotating the swirl charging chute.   The blast furnace raw material discharged from the lower bunker is a blast furnace raw material deposited inside the raw material storage tank and a plurality of ports of the upper bunker so that the initial stage of discharge is coarse and the final stage of discharge is fine. Control the segregation state of the coarse and fine grains of the raw material, swivel the swirl charging chute so that the tip of the swirl charging chute moves from the center of the blast furnace toward the peripheral side, the center of the blast furnace 2. The raw material charging method into the blast furnace according to claim 1, wherein coarse blast furnace raw material is deposited on the part.

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