JP2006283079A - Sintering operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sintering operation method by which air permeability in a sintering raw material bed can be controlled more excellently and quantitatively than ever before. <P>SOLUTION: A sintering operation method, where air permeability controlling rods are inserted from above into the sintering raw material bed charged on the pallet of a downward suction type Dwight-Lloyd sintering machine to form ventilation grooves in the sintering raw material bed and then the surface layer is ignited to continuously manufacture sintered ore cakes, is improved. To be concrete, the insertion depth of the air permeability controlling rods is altered on the basis of the thickness of a wet zone determined in accordance with the properties of the raw materials for sintering to be charged. Moreover, it is preferable that the insertion depth of the air permeability controlling rods is further regulated on the basis of the amount of dusting in an ore discharge part. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a sintering operation method, and in particular, in a downward-inspired Dwight-Lloyd-type sintering machine, the air permeability of the sintering raw material layer is improved by controlling the insertion depth of a so-called `` venting bar '', high quality, The present invention also relates to a sintering operation method that achieves high productivity.

  One of the sources of iron charged to blast furnaces that melt pig iron is called sintered ore, which is a sintered raw material filled in layers (also called compound raw materials, powdered iron ore, silica, serpentine, limestone, dolomite There is a so-called “artificial iron ore” obtained by burning a mixture of charcoal and carbonaceous materials). This sintered ore is generally manufactured using a Dwight-Lloyd type (hereinafter referred to as DL type) sintering machine, and the DL type sintering machine 1 circulates for a certain length as shown in FIG. A plurality of box-shaped pallets 3 with a great bottom are attached to the endless track 2, and the sintered raw material is continuously fed from a feeding hopper 3 via a chute (drum chute) 5 onto a moving pallet 3. The sintered raw material layer 6 is formed by charging, and the surface layer of the sintered raw material layer 6 is ignited by using an ignition furnace 8 while taking in air upward or downward through a wind box (wind box) 7. It is burned and solidified into a cake by cooling after melting a part of iron ore powder, ironmaking material and the like. This cake is discharged from the pallet 3 to the outside of the sintering machine 1 on the terminal side (referred to as the ore removal section 9), then crushed and cooled to obtain a sintered ore having a desired size and strength in a blast furnace. . In the blast furnace, one having a diameter of 5 mm or more is used.

  By the way, in this DL type sintering machine 1, a sintered raw material is continuously charged onto the pallet 3 having a width of 2000 to 5000 mm at a layer height of about 500 to 700 mm to form a packed layer. In order to ensure good air permeability of the binder material layer, a coarse sintered raw material is formed in the lower layer portion so that the porosity of the lower layer portion of the sintered material layer 6 to be formed is as large as possible from the upper layer portion. Consideration is given to segregating and filling fine-grained sintering raw materials in the upper layer portion. Further, before the sintered raw material is charged into the pallet 3, a certain amount of water (about 6 to 12% by mass, depending on the blending (kind) of the sintered raw material) is added and granulated by a mixer or the like. The desired particle size distribution is formed.

  However, since the sintering reaction proceeds downward in the DL-type sintering machine 1 with the downward suction, when the moisture added to the sintering raw material evaporates, the vapor moves in the sintering raw material layer 6 from the upper side to the lower side. Finally, it condenses in the lower layer, forming a so-called “wet zone”. Here, for reference, the in-layer situation in which the sintering reaction is in progress is schematically shown in FIG. That is, from the upper side to the lower side, the cooled “sintered ore zone” 10, “burning zone (red tropics)” 11 in which combustion of carbonaceous powder, melting of ore powder or the like (so-called “sintering reaction”) occurs. The “dry zone” 12 where the water has evaporated, the “wet zone” 13 where the steam has condensed, and the “sintered raw material zone” 14 which maintains the initial state of charging are formed.

  In general, in the production of sintered ore, there is a certain relationship between the air permeability of the sintered raw material layer 6 and the productivity of the sintered ore (the better the air permeability, the higher the productivity). Depends on the amount of water added when the sintered raw material is granulated in advance. Therefore, the “wet zone” 13 has a great influence on the air permeability of the sintered raw material layer 6, and the air resistance of the sintered raw material layer 6 increases as the “wet zone” 13 becomes thicker (that is, the air permeability). Work in the direction of making it defective). In addition, the lower layer portion is slower to cool than the upper layer portion and has a large heat retention effect, so that the “red tropics” 11 are enlarged and hinder the overall air permeability. Therefore, the air permeability in the lower layer part greatly affects the productivity improvement of the sintered ore.

  Therefore, various measures for improving the air permeability in the DL type sintering machine have been conceived conventionally. For example, a rod-shaped body with one end fixed to the lower layer portion in the sintering raw material layer filled on the grate on the bottom surface of the pallet is advanced to the pallet. In order to improve the air permeability of the lower layer part, a cavity is formed by inserting the direction parallel to the great surface (see Patent Document 1). Usually, the rod-like body (hereinafter referred to as a ventilation control rod) is provided in a plurality of stages or in a staggered arrangement with a certain distance in the width direction of the sintered raw material layer when viewed in a longitudinal section. Further, as shown in FIG. 4, the ventilation control rod 15 is inserted so as to be substantially perpendicular to the surface of the sintering raw material layer 6 (may be inclined to some extent) as shown in FIG. A technique for improving the air permeability of the lower layer part by forming a plurality of rows of concave grooves (hereinafter referred to as ventilation grooves 16) having a predetermined depth in the binding material layer 6 is also disclosed (see Patent Document 2).

  However, according to the technique described in Patent Document 1, a cavity for improving ventilation is formed horizontally in the lower layer portion of the sintering raw material layer with respect to the great surface of the pallet. If many cavities are not provided, there is a problem that it is not very effective in improving air permeability. Further, in the technique described in Patent Document 2, as shown in FIG. 4, a plurality of ventilation grooves 16 are formed in the width direction of the sintering raw material layer 6. Since the air permeability becomes large, the air permeation is disturbed when the entire sintering raw material layer 6 is seen, and sintering is performed while causing so-called “uneven burn” in which a good portion and a bad portion of the sintering are mixed in an island shape. Will be in operation. As a result, there is a problem in that sintered ore having a weak strength is produced in large quantities and the sintering yield is lowered. Further, since the ventilation groove 16 is formed at the stage where the surface of the sintering raw material is still inclined in the feed section, the deposition of the sintering raw material is disturbed during the subsequent flattening operation, and the ventilation groove 16 is formed. A part of the blockage is blocked, and the “uneven burn” is further promoted.

  In addition, the use of these ventilation control rods 15 has been conventionally performed based on the past experience of the operator in the sintering operation, and the number of insertions and the insertion depth have been appropriately determined by the operator's judgment. In other words, based on the observation of the “unevenness burn” situation and the production status, the operator decides the number of insertions and / or the insertion depth by trial and error so as to suppress the “unevenness burn” and increase the productivity. It was in operation. Further, as in Patent Document 2, in order to improve productivity, an operation that the operator considers appropriate is performed within 2/3 of the sintering raw material layer thickness with respect to the change of the sintering raw material.

In this way, the downward DL type sintering machine 1 has been provided with the vertical type air flow control rod 15 from before, but the air flow control method using it is the operation of raw material properties, air flow properties, etc. Rather than being based on a certain relationship between factors, the advent of a more ambiguous and more quantitative use was eagerly desired. In particular, in recent years when high-quality iron ore powder as an iron source has been depleted, the use of iron ore powder containing highly crystallized water has increased, and the management of moisture and air permeability of the sintered raw material layer 6 has become much more difficult than before. This demand is even higher.
JP-A-2-263935 JP-A-5-295456

  In view of such circumstances, an object of the present invention is to provide a sintering operation method in which the air permeability of a sintering raw material layer is quantitative and better controllable than before.

  The inventor has intensively studied to achieve the above object, and the results have been embodied in the present invention.

  That is, in the present invention, a ventilation groove is formed in the sintering raw material layer with a ventilation control rod inserted from above in the sintering raw material layer charged on the pallet of the Dwight-Lloyd sintering machine that sucks downward. In the sintering operation method in which the surface layer is ignited and the sintered ore cake is continuously produced, the insertion depth of the ventilation control rod is set to the thickness of the wet zone determined according to the properties of the sintered raw material to be charged. It is a sintering operation method characterized by changing based on. In this case, it is preferable that the insertion depth of the ventilation control rod is further adjusted based on the amount of dust generated at the discharge portion. Moreover, it is preferable that the main iron ore of the sintering raw material is a high crystal water-containing ore.

  According to the present invention, the air permeability of the sintered raw material layer can be quantitatively and better controlled than before. As a result, even if the ventilation control rod is used, “uneven burn” is suppressed, and the quality (particle size distribution, strength, etc.) of the sintered ore becomes constant without reducing productivity. In particular, the present invention is effective for a sintering operation of a sintering raw material mainly composed of iron ore powder containing high crystal water.

  Hereinafter, the best embodiment of the present invention will be described based on the background of the invention.

In general, the sintering of the sintering raw material particles proceeds in the following flow as described above (see FIGS. 5 and 6). After the sintered raw material is loaded on the moving pallet 3 and the packed layer is formed with a predetermined layer thickness, the carbonaceous material (coke scrap) mixed in the surface layer portion by ignition burns, and is about 1200 to 1500 ° C. At the same time as the temperature rises, a part of the sintering raw material melts and the particles start to fuse with each other. This portion is called “combustion zone” or “red tropical”, but when cooled, it becomes a so-called “cake-like sintered body”. And since the wind box 7 is a negative pressure, air flows downward from a surface layer part. This air is heated by passing through the combustion zone, and heats the sintering raw material immediately below the combustion zone. The heated sintering raw material loses moisture by evaporation, and the evaporated moisture further moves into the lower sintering raw material layer 6 and condenses. Therefore, there is a “dry zone” 12 immediately below the “combustion zone” 11 and a “wet zone” 13 below it. The temperature of the gas passing through each of these zones (air is a mixed gas such as CO, CO ₂ , H ₂ O, etc. in various reactions above) is 100 ° C. or higher in the “dry zone” 12, The “wet zone” 13 is 60 to 70 ° C. Since the sintering raw material existing in the “dry zone” 12 is continuously heated, it becomes the “combustion zone” 11 after reaching the ignition temperature of the carbonaceous material. In such a flow, when the lowermost end of the sintering raw material layer 6 becomes the “combustion zone” 11, the “combustion zone” 11 and the cooled “cake-like sintered body” overlapped thereabove. Since it will be in a state, it will be discharged | emitted from the excavation part 9 of the sintering machine 1 out of the machine.

  Therefore, the inventor manufactures sintered ore with the downward-suction DL-type sintering machine 1 equipped with the ventilation control rod 15 described in Patent Document 2, and the sintered raw material layer is a product whose air permeability is a product. Focusing on the productivity and quality of the ore, we decided to develop a quantitative and superior breathability control technology. As described above, the lower layer portion of the sintering raw material layer 6, particularly the “wet zone” 13, plays an important role with respect to the overall air permeability. Therefore, the thickness of the “wet zone” and the air permeability control It was examined using a test pan and an actual machine whether or not there was a certain relationship between the insertion depth of the rod 15. As a result, we found that if the relationship was determined in advance for each different composition (type) of the sintering raw material, it was possible to control the air permeability superior to the conventional one, and the present invention was completed based on that requirement. is there.

  First, in the present invention, “wet band thickness” of various sintered raw materials having different compositions is determined in advance using a test pan or an actual machine. Specifically, thermometers are arranged in multiple stages at a certain distance in the longitudinal (height) direction of the sintering raw material layer, and the test sintering is actually performed, and the sintering time and temperature are 60 to 70. The relationship with the region entering the ℃ (a certain distance in the sintering raw material layer) was obtained, and the maximum value of the region entering the 60 to 70 ℃ (the certain distance in the sintering raw material layer) was defined as “wet zone thickness”. . Since the “wet zone” 13 changes every moment depending on the sintering time, the maximum value that has the greatest influence on the air permeability is adopted. The “wet band thickness” determined in this way and the type of the corresponding blended raw material are conveniently stored in a file on a computer or the like for later use.

Next, the thicker the “wet zone thickness”, the greater the airflow resistance of the sintered material layer. Therefore, the “wet zone thickness” and the insertion depth of the air flow control rod into the sintered material layer, which reduces the airflow resistance, This relationship is expected to be almost linear. And, when the operation with the maximum strength (evaluated by the production rate of sinter: tons (t) / hour (hr) / area (m ² )) with the strength acceptable as a sinter is possible with the actual machine Fig. 1 shows the relationship between the "wet band thickness" and the "insertion depth of the ventilation control rod". Confirmed to do. In other words, if this relationship is utilized, a ventilation groove is formed in the sintering raw material layer by a ventilation control rod inserted from above into the sintering raw material layer charged on the pallet of the Dwight-Lloyd type sintering machine that sucks downward. In the sintering operation method in which the surface layer is ignited and the sintered ore cake is continuously produced, the insertion depth of the ventilation control rod is determined according to the properties of the sintered raw material to be charged. If it is set based on the “band thickness”, a sintered ore having a desired quality can be manufactured without impairing productivity. Therefore, such an operation method is the present invention. The reason why there are a plurality of straight lines in FIG. 1 is that the air permeability varies depending on the thickness of the sintering raw material layer and the interval of the air flow control rods in the width direction even with the same raw material.

  Subsequently, even if the sintering raw material has the same composition (kind), it cannot be uniform at all, and the properties of the sintering raw material to be charged vary with time. Therefore, even if the operation method according to the present invention described above is used, the set insertion depth of the air flow control rod may not be appropriate in some cases, and “uneven burn” may occur. Therefore, the inventor decided to add fine adjustment to the present invention for the occurrence of “unevenness burn” due to such disturbance. That is, the amount of dust generated from the discharge part (exhaust rear part) of the cake-like sintered body of the sintering machine is measured, and the ventilation control rod previously set in the implementation of the present invention so as to reduce the amount of dust generation Is finely adjusted upward. Thereby, “unevenness burning” within the same composition of the sintering raw material can be suppressed. Here, the magnitude of the dust generation amount may be constantly measured by providing a sensor for detecting the dust amount in the atmosphere, or may be determined by a change with time of the dust amount collected by the dust collector.

  In the present invention described above, the kind of the sintering raw material is not particularly limited. However, the present invention is particularly effective for a sintered raw material containing a large amount of iron ore containing high crystal water. Although it is difficult to control the breathability of these sintered raw materials, it is possible to appropriately control the breathability by applying the present invention.

  Further, in the practice of the present invention, the ventilation control rod scrapes and flattens the surface layer of the charged sintered raw material layer on the downstream side of the chute position where the sintered raw material is charged into the pallet. Place upstream of the “cut-off plate”. The insertion depth of the air flow control rod into the sintering material layer is performed by a mechanical lifting device. Therefore, in order to carry out the present invention, once the blending raw material to be sintered is determined, the “wet band thickness” is determined from the data for each different blending raw material stored in the computer, and the relationship shown in FIG. 1 is used. Basically, the insertion depth of the ventilation control rod is determined, and the lifting device is operated and set to that value. This setting may be performed manually or automatically.

The sintering operation was carried out with a DL-type sintering machine with a downward-venting aeration equipped with a pallet with a width of 4500 mm and six air-controlling rods capable of moving up and down at an interval of 700 mm. The sintered raw material (mixed raw material) used was a highly crystallized water on the basis of the mixed raw material A, which is a mixture of powdered hematite-type iron ore, return mineral, various SiO ₂ -containing raw materials, limestone, dolomite, and powdered coke Various maramba ores containing selenium. In other words, in addition to the basic blending raw materials, five kinds of sintered raw materials were prepared in which Maramamba ore was made to differ from 0, 10, 20, 30, 40% by mass.
(Comparative example)
First, a conventional operation was performed in which the ventilation control rod was inserted into the sintering material layer at the operator's discretion. In other words, with respect to the 600 mm sintering raw material layer, the tip of the ventilation control rod is inserted so as to reach a depth of 300 mm from the surface of the sintering raw material layer, and six concave ventilation grooves are formed in the sintering raw material layer. I ignited after letting.

As a result of sintering, except for the case where the blending material of Mara Mamba ore is 0% by mass, “uneven burn” always occurs, and in order to obtain a sintered ore having an acceptable drum strength, the sintering yield decreases. was there. Therefore, as shown in FIG. 2, the production rate decreased considerably as the blending amount of maramamba ore increased.
(Example of the present invention)
First, the “wet band thickness” corresponding to the blended raw materials having five different blends was output from a computer stored in advance. Then, from the relationship shown in FIG. 1, the insertion depth of the ventilation control rod corresponding to each “wet band thickness” was read to determine the set value. The production rate as a result of operation with each set value is as shown in FIG. In the case of a sintered raw material containing 40% by mass of Mara Mamba ore, there was a tendency to increase the dust generation amount measured by the dust generation detection sensor. A fine adjustment was made to reduce the amount of dust.

  By applying the present invention, it is clear that a high production rate can be ensured even for highly crystallized water-containing ores for which ventilation control is difficult. That is, according to the present invention, the air permeability of the sintered raw material layer can be quantitatively controlled better than before. As a result, even if the ventilation control rod is used, “uneven burn” is suppressed, and the quality (particle size distribution, strength, etc.) of the sintered ore becomes constant without reducing productivity. In particular, the present invention is effective for a sintering operation of a sintering raw material mainly composed of iron ore powder containing high crystal water.

It is a figure which shows the relationship between the "wet zone thickness" of the sintering raw material which forms the foundation of this invention, and "the insertion depth to the sintering raw material layer of a ventilation control rod." It is a figure which shows the production rate at the time of sintering each compounding raw material obtained by the conventional sintering operation. It is a figure which shows the production rate at the time of sintering each mixing | blending raw material obtained by the sintering operation to which this invention is applied. It is a perspective view explaining the perpendicular | vertical ventilation control rod arrange | positioned in DL type | mold sintering machine. It is a figure which shows typically the phenomenon which a sintering raw material layer raise | generates during sintering with a longitudinal cross-section. It is a figure which shows typically the phenomenon which a sintering raw material layer raise | generates during sintering in a cross section. It is a cross-sectional view explaining the structure of a general DL type sintering machine.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DL type sintering machine 2 Endless track 3 Pallet 4 Feeding hopper 5 Chute 6 Sintering raw material layer 7 Wind box 8 Ignition furnace 9 Exhaust section 10 Sintered ore zone 11 Combustion zone (red tropics)
12 Drying zone 13 Wet zone 14 Sintering raw material zone 15 Ventilation control rod 16 Ventilation groove

Claims (3)

In the sintering raw material layer charged on the pallet of the Dwight-Lloyd sintering machine that sucks in downward, a ventilation groove is formed in the sintering raw material layer with a ventilation control rod inserted from above, and then the surface layer is ignited. In the sintering operation method for continuously producing a sintered ore cake,
A sintering operation method characterized in that the insertion depth of the ventilation control rod is changed based on the thickness of a wet strip determined according to the properties of the sintering raw material to be charged.   The sintering operation method according to claim 1, wherein the insertion depth of the ventilation control rod is further adjusted based on the amount of dust generation in the exhaust portion.   The sintering operation method according to claim 1 or 2, wherein the main iron ore of the sintering raw material is an ore containing high crystal water.

Images