JP2014129570A - Method for loading a to-be-sintered raw ingredient - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for loading a to-be-sintered raw ingredient capable of stabilizing, at a high level, the yield of a sintered ore by abating classifying irregularities of a bar screen attributed to the variation of the granulating morphology of the to-be-sintered raw ingredient.SOLUTION: In a method for loading, into a sintering pallet 25 while classifying, a to-be-sintered raw ingredient S including, as an iron ore, an ore powder having a particle size distribution including at least 35 mass% of 500 μm-under particles and flowing downward out of a loading chute 13 through a bar screen 14 furnished with multiple bars 16 to 18 extending, via gaps along the width direction of the loading chute 13, along the flow-down direction of the to-be-sintered raw ingredient S in a state where the gaps of bars 16 to 18 adjacent along the top-bottom direction on a profile view representation expand toward the downstream side of the bars 16 to 18, the gap d of bars 16 to 18 adjacent along the horizontal direction on a plane view representation is set at 3 mm or above and 12 mm or below. The opening angle φ of the bars 16 to 18 adjacent along the top-bottom direction on the profile view representation is set at 1.2° or above and 3.0° or below. The loading velocity V of the to-be-sintered raw ingredient S is set at 0.3 m/s or above and 0.7 m/s or below.

Description

  The present invention relates to a method for charging a sintering raw material into a sintering pallet of a sintering machine, and in particular, the sintering raw material is formed by a bar screen composed of a plurality of bars extending along the flow direction of the sintering raw material. The present invention relates to a method of charging a sintered pallet while classifying.

  In the sintering process for producing sintered ore using iron ore such as fine ore, condensate such as fine coke, and lime such as quick lime as a sintering raw material, a part or all of the sintering raw material is appropriately granulated. After granulating into a granulated product having a diameter, and inserting it into a sintering pallet (hereinafter, simply referred to as “pallet”) of a sintering machine, the surface layer of this sintering raw material is ignited, In general, the condensed material is oxidized while sucking outside air from below, and iron ore (powder ore) is sintered using heat generated during oxidation.

However, in the above-described sintering process, when the sintering raw material layer charged in the sintering pallet has a uniform particle size distribution in the height (depth) direction, there are the following problems.
The surface layer part of the sintering raw material layer is cooled by the sucked outside air and the temperature rise is insufficient. On the other hand, the gas passing through the lower part of the sintering raw material layer has a higher temperature than when passing through the upper sintering raw material layer. Therefore, the ventilation resistance is increased as compared with the upper sintered raw material layer, and the amount of air sucked (aeration amount) is reduced. As a result, sintering of the sintering raw material did not proceed, which was a factor in reducing the yield of sintered ore and reducing the production amount (firing amount).

  Accordingly, in the surface layer portion of the sintering material layer, the heat receiving area is increased by reducing the average particle size of the sintering material to promote the sintering, while in the lower part of the sintering material layer, the average particle size of the sintering material is increased. It is desirable to increase the diameter to improve air permeability.

The above-mentioned countermeasure is also called segregation charging, and various techniques have heretofore been proposed in order to obtain a predetermined particle size segregation. For example, in Patent Document 1, a bar screen (fluid) composed of a plurality of bars (strip members) extending along the flow direction of the sintering raw material is provided on the downstream side of the charging chute of the sintering raw material. A technique has been proposed in which a sintering raw material flowing down from an input chute is charged into a sintering pallet while being classified by a bar screen. The plurality of bars are arranged with an interval in the width direction of the charging chute, and the interval between the bars adjacent in the vertical direction as viewed from the side is increased toward the downstream side.
By the method described in Patent Document 1, segregation charging of the sintered raw material is realized, and the yield of the sintered ore is improved. If this yield is made substantially constant, the amount of firing can be increased. Therefore, the productivity of the sintered ore calculated by the product of the amount of firing (ton / day / m ² ) and the yield (%) (ton / Day / m ² ) is greatly improved.

  Moreover, in patent document 2, the diameter of the bar (bar-shaped material) which forms a bar screen, the average value of the gap of a bar screen, the inclination angle of a bar screen, and the inclination angle of a (charging) chute are set to an appropriate range. On the other hand, a method for maximizing the grain size segregation expansion effect has been proposed.

Japanese Unexamined Patent Publication No. 63-190125 Japanese Patent Laid-Open No. 03-249137

  However, the pseudo particle size of the sintered raw material (granulated material) charged into the sintering machine varies depending on the granulated moisture, the particle size of the sintered raw material, and the like. Along with this, the granulation form of the granulated product also changes. Therefore, depending on the charging speed of the sintering raw material, the classifying ability of the bar screen is reduced, and the techniques described in Patent Document 1 and Patent Document 2 cannot achieve the target particle size segregation, resulting in variations in particle size segregation. The problem that becomes large occurs. Hereinafter, in this specification, it demonstrates as a sintering raw material = granulated material charged in a sintering machine.

  The present invention has been made in view of such circumstances, and by reducing the variation in classification in the bar screen caused by the change in the granulation form of the sintering raw material, the yield of the sintered ore can be stabilized at a high level. It is an object of the present invention to provide a method for charging a sintered material.

In order to achieve the above object, the present invention provides a plurality of materials that extend in the flow direction of the sintered raw material at intervals in the width direction of the charging chute for charging the sintered raw material supplied from the drum feeder into the sintering pallet. The bar screen in which the interval between the bars adjacent to each other in the vertical direction when viewed from the side widens toward the downstream side of the bar flows down from the charging chute, and the 500 μm under is 35% by mass or more. In the method of charging into the sintering pallet while classifying the sintering raw material with the powder ore having a particle size as iron ore,
The gap d between the bars adjacent in the horizontal direction in a plan view is 3 mm or more and 12 mm or less, and the opening angle φ of the bars adjacent in the vertical direction in a side view is 1.2 ° or more and 3.0 ° or less. The charging speed V of the raw material is 0.3 m / s or more and 0.7 m / s or less.

  Here, the charging speed of the sintered raw material is the speed at which the sintered raw material is discharged from the drum feeder to the charging chute (= the rotational speed (m / s) of the drum feeder). Generally, the charging of the sintering raw material is a continuous flow from the drum feeder to the sintering pallet through the charging chute and the bar screen. For this reason, in the present invention, the speed at which the sintered raw material is discharged from the drum feeder to the charging chute is represented as the charging speed of the sintered raw material.

In recent years, pulverization of iron ore has progressed, and the proportion of fine powder in the fine ore tends to increase. Along with this, the granulation form of the granulated product when granulating sintered raw materials containing fine ore has also changed, the amount of adhering fine powder in the granulated product has increased, and the granulated product has collapsed. It's getting easier. Specifically, when the granulated material (sintering raw material) is charged into the sintering machine, the drop impact of the granulated material from the drum feeder to the charging chute and the transfer of the granulated material on the charging chute. When the granulated product is subjected to dynamic impact and impact of dropping the granulated product from the charging chute to the bar screen, the collapse phenomenon of the granulated product becomes remarkable.
The inventors of the present invention have found that the collapse phenomenon of the granulated product becomes prominent due to the change in the granulated form of the granulated product, so that the classification ability of the bar screen is reduced and the variation in the size segregation is increased. discovered.

  In order to solve the above-mentioned problems, the present invention focuses on the granulation form of the granulated product, and regulates the charging speed of the granulated product (sintered raw material), whereby the granulated product at the time of charging the granulated product. This is the first proposal of a charging segregation method based on the collapse of At that time, by defining the gap between the bars constituting the bar screen and the opening angle of the bars, the variation in classification in the bar screen can be reduced. As a result, high-level stable segregation charging, which is impossible with the conventional method, is possible, and high-level yield can be stably realized.

  When using a sintered raw material in which iron ore is a fine ore with a particle size of 35% by mass or more under 500 μm, the gap d of the bar constituting the bar screen, the opening angle φ of the bar, and the charging speed of the sintered raw material When V is out of the set range, as will be described later, the classification efficiency is lowered, and the desired particle size segregation cannot be realized.

  Further, in the method for charging a sintered material according to the present invention, a liquid may be supplied to the surface of the bar screen.

  In general, it is known that when the moisture content of the sintering material increases, the adhesion of the sintering material also increases, and the sintering material tends to adhere to the bar screen. However, by supplying a small amount of liquid such as water to the bar screen so that the bar screen is always wet with the liquid (a state where a liquid film is formed on the surface of the bar screen), the sintering raw material is transferred to the bar screen. The adhesion force can be suppressed.

  In the charging method of the sintered raw material according to the present invention, the gap d of the bar constituting the bar screen, the opening angle φ of the bar, and the charging speed V of the sintered raw material are set within appropriate ranges, thereby sintering. The variation in classification in the bar screen due to the change in the granulation form of the raw material can be reduced. As a result, the yield of sintered ore can be highly stabilized.

It is a schematic diagram of the sintering raw material charging apparatus used for the charging method of the sintering raw material which concerns on one embodiment of this invention. (A) is a side view of a bar screen constituting the sintered raw material charging device, (B) is a partial plan view of the bar screen, and (C) is an end view of the bar screen of (B) as viewed from the front end side. (D) is the end view which looked at the bar screen of (B) from the base end side. It is the graph which showed the influence which the clearance gap d of a bar has on the segregation degree. It is the graph which showed the influence which the opening angle (phi) of a bar has on the segregation degree. It is the graph which showed the influence which the charging speed V of a sintering raw material has on the variation in the segregation degree.

Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention.
The schematic diagram of the sintering raw material charging apparatus 10 used for the charging method of the sintering raw material which concerns on one embodiment of this invention is shown in FIG.
Sintering raw material charging device 10 is a sintered raw material S composed of iron ore composed of fine ore having a particle size of 35% by mass or more under 500 μm, a coagulant such as fine coke, and lime such as quick lime. It is a device that is charged into a pallet 25 (sintering pallet) of a dwy-toroid type sintering machine (not shown). In the following description, for the sake of convenience, the traveling direction of the pallet 25 is referred to as the “front” side, and the opposite direction is referred to as the “rear” side.

  In a dwy-toroid type sintering machine, a plurality of pallets 25 traveling on an endless rail consisting of a forward path and a return path arranged in a vertical direction are connected in a rosary shape to constitute an endless conveyor. A plurality of pallets 25 are moved along the endless rails by rotating sprockets respectively provided in the supply section for supplying the sintering raw material S to the pallet 25 and the discharge section for discharging the manufactured sintered ore. Go around.

  The sintered raw material charging device 10 is installed in the feed section, and stores a storage hopper 11 for storing the sintered raw material S, a drum feeder 12 for cutting the sintered raw material S from the storage hopper 11, and cutting from the drum feeder 12. And a charging chute 13 for charging the sinter raw material S to the pallet 25. Further, on the downstream side of the charging chute 13, a bar screen 14 for classifying the sintering raw material S flowing down from the charging chute 13, and a liquid supply means for supplying water W (an example of a liquid) to the surface of the bar screen 14. As a spray nozzle 23.

The rotational speed of the drum feeder 12 is controlled so that the charging speed V of the sintered raw material S is 0.3 m / s or more and 0.7 m / s or less. The rotational speed of the drum feeder 12 can be easily controlled even during operation.
The charging chute 13 is disposed below the drum feeder 12 and has an inclined surface that is inclined downward from the front side toward the rear side.

  The bar screen 14 disposed on the downstream side of the charging chute 13 has a gap d in the width direction of the charging chute 13 in a plan view and flows in the direction of flow of the sintering material S (perpendicular to the width direction of the charging chute 13) The base end portion is downstream of the charging chute 13 in a state inclined downward in the flow direction (backward) of the sintering raw material S. It is attached to the back side of the end portion (rear end portion) (see FIGS. 2A to 2D). The horizontal gap d between the bars 16, 17, 18 is set to 3 mm or more and 12 mm or less.

  Each bar 16, 17 and 18 is made of a metal bar such as iron (diameter: about 5 mm to 30 mm, length: about 500 mm to 1500 mm), and rotates around the material axis. The cross-sections of the bars 16, 17, and 18 are usually circular, but are not particularly limited as long as the sintering raw material S can be classified. For example, the bars 16, 17, and 18 may have various shapes such as an ellipse, an egg, or a triangle or a quadrangle. It may be square.

When the bar screen 14 is viewed from the front end side or the base end side, the virtual line connecting the front ends or the base ends of the adjacent bars 16, 17, 18 in order is V-shaped (inverted V-shaped). A three-stage arrangement of a stage (upper stage) bar 16, a second stage (middle stage) bar 17, and a third stage (lower stage) bar 18 is employed (see FIGS. 2C and 2D).
The intervals a1 and a2 on the downstream side (front end side) of the bars 16, 17, and 18 adjacent in the vertical direction when viewed from the side are wider than the intervals b1 and b2 on the upstream side (base end side). That is, the depression angle α of the upper bar 16 <the depression angle β of the middle bar 17 <the depression angle γ of the lower bar 18 (see FIG. 2A). The depression angle α of the upper bar 16 is preferably about 29 ° to 43 ° for realizing segregation charging, and the opening angle φ of the bars 16, 17, 18 adjacent in the vertical direction when viewed from the side is 1.2 ° or more. It is set to 3.0 degrees or less.
The depression angles α, β, and γ are angles formed by the central axes of the bars 16, 17, and 18 and the horizontal plane, and the opening angle φ is an angle between the central axes of the bars 16, 17, and 18.

  The bar screen 14 has a larger interval on the downstream side of the bars 16, 17, and 18 adjacent in the vertical direction when viewed from the side, than the interval on the upstream side. S falls on the pallet 25. On the other hand, the pallet 25 travels from the downstream side of the bar screen 14 toward the upstream side. Accordingly, the sintered raw material S having a larger particle size than the sintered raw material S having a smaller particle size first falls on the pallet 25, and the segregation charging in which the particle size of the sintered raw material S increases toward the lower layer. Is realized.

  A plurality of spray nozzles 23 serving as liquid supply means for supplying a liquid to the surface of the bar screen 14 are arranged below the base end portion of the bar screen 14 at intervals in the width direction of the charging chute 13 (FIG. 1). reference). Each spray nozzle 23 sprays water from the lower front of the bar screen 14 toward the base end of the bar screen 14. The water W adhering to the base end portion of the bar screen 14 due to water spray from the spray nozzle 23 flows to the tip end portion through the bars 16, 17 and 18. Thereby, a water film can be formed over the entire surface of the bars 16, 17, 18.

The spraying angle θ of the spray nozzle 23 with respect to the horizontal plane is preferably 0 ° or more and less than γ, that is, the angle between the horizontal line and the lowermost bar 18 in the vertical plane including the lowermost bar 18 (FIG. 2). (See (A)).
If the water spraying angle θ of the spray nozzle 23 is less than 0 °, the water W ejected from the spray nozzle 23 penetrates the bar screen 14 and the water W hardly flows to the tips of the bars 16, 17, 18. Is killed. On the other hand, when the water spray angle θ of the spray nozzle 23 is equal to or larger than γ, there is a problem that it is difficult to install the spray nozzle 23 because the flowing down sintered raw material S and the charging chute 13 become obstacles.

The amount of water supplied from the spray nozzle 23 to the bar screen 14 is preferably 10 cc / min to 1000 cc / min per bar.
In addition, instead of water spray, liquid spray or dripping water may be used as the liquid supply means.

Using the sintering raw material charging apparatus 10 having the above-described configuration, the procedure for charging the sintering raw material S, in which the iron ore is a fine ore having a particle size of 35% by mass or more under 500 μm, into the pallet 25 of the sintering machine, It is as follows.
(1) Water is sprayed from the spray nozzle 23 toward the bar screen 14 so that the bar screen 14 is always wet with water W.
(2) In the state which controlled the rotational speed of the drum feeder 12 so that the charging speed V of the sintering raw material S might be 0.3 m / s or more and 0.7 m / s or less, it baked with the drum feeder 12 from the storage hopper 11 The raw material S is cut out and dropped onto the charging chute 13.
(3) The sintered raw material S dropped on the charging chute 13 flows down on the charging chute 13, is classified by the bar screen 14, and is charged into the pallet 25.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the configuration described in the above-described embodiment, and is within the scope of matters described in the claims. Other possible embodiments and modifications are also included. For example, although the sintering raw material charging apparatus in the above embodiment includes the liquid supply means, the liquid supply means may not be provided. Moreover, in the said embodiment, although the bar screen is made into three steps, what is necessary is just to be two or more steps | paragraphs (for example, four steps).

A verification test carried out to verify the effects of the present invention will be described.
The bar screen used for the verification test is of the type shown in the above embodiment, and is composed of a bar made of a round bar having a diameter of 10 mm and a length of 800 mm. The gap d between the bars adjacent in the horizontal direction in plan view is 2.5 mm to 16 mm, the opening angle φ of the bar adjacent in the vertical direction in side view is 0.8 ° to 4.0 °, and the depression angle γ of the lower bar Was 41 °.
The charging speed V of the sintered material calculated from the rotation speed of the drum feeder is 0.2 m / s to 1.0 m / s, the length of the charging chute is 500 mm, and the inclination angle of the charging chute is 44 °. is there.
In the test for verifying the influence of the charging speed V of the sintering raw material on the variation in the segregation degree, the effect of supplying the liquid to the bar screen was also verified. The liquid supply means at that time was a water spray.

  The sintering raw material was collected from the actual machine charging section, and the amount used per test was about 500 kg. At that time, the moisture ratio in the sintered raw material was 6% by mass to 9% by mass. However, the water ratio = water / (water + sintering raw material).

  The verification test was performed 5 times under the same conditions. For the evaluation of the verification test, the segregation degree and the variation in the segregation degree calculated from the columnar sample extracted from the sintering raw material layer deposited on the sintering pallet were used. Specifically, [(the average diameter of the sintered raw material in the lower layer 50 mm of the sample−the average diameter of the sintered raw material in the upper layer 50 mm of the sample) / the average diameter of the sintered raw material in the entire layer of the sample] is obtained for each time, 5 times Was the segregation degree. In addition, the difference between the maximum value and the minimum value among the above five values was defined as variation in the degree of segregation.

The average diameter of the sintered raw material was calculated by the following method.
After drying the sampled sintered material, classification is performed using 9.5 mm, 8.0 mm, 6.7 mm, 4.75 mm, 2.8 mm, 2.0 mm, 1.0 mm, and 0.5 mm sieves in the order of description. In each group, the representative diameter and the mass ratio are obtained (see JIS Z8801-1 “Sieving for testing—Part 1: Metal mesh sieve”). And the product of a representative diameter and mass ratio is computed for every group, and let those sum total be an average diameter of a sintering raw material. However, the representative diameter is 12.5 mm when the sieve mesh is 9.5 mm over, 0.25 mm when the sieve mesh is 0.5 mm under, and the other is the center value of the sieve mesh (for example, a group of 9.5 mm under to 8.0 mm over) Then, the center value of the sieve mesh is 8.75 mm.)

Hereinafter, the verification test results will be described.
FIG. 3 is a graph showing the effect of the bar gap d on the segregation degree. From the same figure, a sintered raw material in which a fine ore having a grain size of 20% by mass of 500 μm under is iron ore (hereinafter referred to as “sintered raw material of 20% by mass under 500 μm”. The same applies to other mass ratios. In the case of notation), when the gap d between the bars is 10 mm or less or 30 mm or more, it is understood that the degree of segregation is greatly reduced. On the other hand, in the case of a sintered raw material of 500 μm under 35 mass%, when the bar gap d is less than 3 mm or more than 12 mm, the segregation degree is significantly reduced, and when the bar gap d is 3 mm or more and 12 mm or less, the segregation degree is Maintains 1 or more.
The pseudo-particle size of the granulated product (sintered raw material) was distributed at about 0.25 mm to 10 mm, and the average particle size was about 3.0 mm to 3.5 mm, which was the same for both raw materials.

  In Patent Document 2, it was described that the particle size segregation was constant even when the gap of the bar was changed from 7 mm to 30 mm. However, in the case of a sintered raw material having a mass of 35 μm under 35 μm, This test result revealed that the segregation degree decreased when the gap d exceeded 10 mm. This is because, when the raw material particle size changes, the fine powder raw material increases and the proportion of the adhering fine powder in the granulated product increases, so that the granulated product tends to collapse and the bar gap d is large (of the granulated product This is probably because the classification effect by the bar screen cannot be obtained when the gap d of the bar is relatively larger than the particle size. That is, it is considered to be due to the difference in the granulation form of the granulated product.

  In the case of a sintered raw material of 500 μm under 35 mass%, assuming that the remaining 65 mass% is core particles, the ratio of fine powder (under 500 μm) to core particles is 35 ÷ 65≈0.54. On the other hand, in the case of a sintering raw material of 500 μm under 20% by mass, assuming that the remaining 80% by mass is core particles, the fine powder ratio with respect to the core particles is 20 ÷ 80 = 0.25. Since the pseudo-particle size after granulation was almost the same, the fine powder ratio increased from 20% by mass to 35% by mass, so that the fine powder ratio with respect to the core particles, that is, the adhered fine powder ratio of the granulated material was about doubled. Will be increased. As a result, the granulated product has a drop impact from the drum feeder to the charging chute, a rolling impact of the granulated product on the charging chute, and a granulated product falling impact from the charging chute to the bar screen. It is thought that the disintegration of the particles became remarkable. When the sintering raw material classified by the bar screen and charged in the sintering pallet was actually verified, an increase in fine powder of 500 μm or less in the pseudo particles was confirmed.

FIG. 4 is a graph showing the effect of the opening angle φ of the bar on the segregation degree of a sintered raw material having a thickness of 35 μm under 35 μm. From the figure, it can be seen that the segregation degree decreases when the opening angle φ of the bar is less than 1.2 ° and more than 3.0 °. When the opening angle φ of the bar is less than 1.2 °, the bar passing rate of the sintered raw material is reduced. On the other hand, when the opening angle φ of the bar is more than 3.0 °, the bar passing rate of the sintered raw material is Increase. As a result, the classification efficiency by the bar screen is lowered, and the segregation degree is lowered.
This phenomenon is not observed when the bar gap d is greater than 12 mm (when the bar gap d is relatively large with respect to the granulated product), and is remarkable when the bar gap d is set to 12 mm or less. It was a problem that occurred. Therefore, it is considered that there was no problem with the conventional technology.

FIG. 5 is a graph showing the influence of the charging speed V of the sintering raw material on the variation in the degree of segregation. From the figure, it can be seen that the variation in the segregation degree increases when the charging speed V of the sintered raw material is less than 0.3 m / s and when it exceeds 0.7 m / s. When the charging speed V of the sintering material is less than 0.3 m / s, the flow of the sintering material on the charging chute is discontinuous, while the charging speed V of the sintering material is 0.7 m / s. When it is super, the impact when the granulated product (sintered raw material) falls becomes large, and the collapse of the granulated product becomes remarkable. As a result, the variation in the degree of segregation increases.
In addition, when the sintered raw material of 500 μm under 40% by mass was compared with the sintered raw material of 500 μm under 35% by mass, the relationship between the charging speed V and the segregation degree was the same, but the segregation degree variation was 500 μm under 35. It was larger than the mass percent sintered raw material.

  Further, FIG. 5 shows that when the liquid is supplied to the bar screen, the variation in the degree of segregation decreases. In particular, when the charging speed V of the sintered raw material is out of the range of 0.3 m / s to 0.7 m / s, this tendency becomes remarkable.

10: sintering raw material charging device, 11: storage hopper, 12: drum feeder, 13: charging chute, 14: bar screen, 16, 17, 18: bar, 23: spray nozzle (liquid supply means), 25: Pallet (sintered pallet), S: raw material for sintering, W: water (liquid)

Claims (2)

Equipped with a plurality of bars extending in the flow direction of the sintering raw material at intervals in the width direction of the charging chute for charging the sintering raw material supplied from the drum feeder into the sintering pallet. With the bar screen in which the interval between the bars adjacent to each other expands toward the downstream side of the bar, the iron ore is a fine ore having a particle size of 500% by mass or more and having a particle size of 35% by mass or more flowing down from the charging chute. In the method of charging the sintering pallet while classifying the raw materials,
The gap d between the bars adjacent in the horizontal direction in a plan view is 3 mm or more and 12 mm or less, and the opening angle φ of the bars adjacent in the vertical direction in a side view is 1.2 ° or more and 3.0 ° or less. A method for charging a sintered raw material, wherein the charging speed V of the raw material is 0.3 m / s or more and 0.7 m / s or less.   2. The method for charging a sintered material according to claim 1, wherein a liquid is supplied to the surface of the bar screen.

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