JP2015151623A - Method for estimating apparent specific gravity and porosity of granules, and method for controlling granulation process - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for rapidly estimating the apparent specific gravity and porosity of granules from the deposition shape of the granules, and a method for stably manufacturing granules based on the estimated apparent specific density and porosity of the granules.SOLUTION: In the method for rapidly estimating the apparent specific gravity and porosity of granules, when granules produced in a granulation process of ores are dropped onto a conveying machine so as to be deposited on the conveying machine for conveyance, the deposition shape and weight of the granules are measured, so that the apparent specific gravity and porosity of the granules can be estimated. In the method for controlling a granulation process, the granulation process of ores is controlled based on the estimated apparent specific gravity and/or porosity of the granules.

Description

  The present invention relates to a method for estimating the apparent specific gravity / porosity of a granulated product and a method for controlling the granulation process.

Conventionally, those shown in Patent Documents 1 and 2 have been developed as techniques for measuring apparent specific gravity and the like of iron ore pellets used as a raw material for a blast furnace.
Patent Document 1 aims to provide a method for measuring the apparent specific gravity of an irregularly shaped porous body with a simple measurement operation and with high accuracy, and the outer surface of the porous body is vacuumed with an impermeable film. After the tight packaging, the apparent volume is calculated by the buoyancy measurement method, and the apparent specific gravity of the sample is calculated by dividing the dry weight of the sample by the apparent volume, and the porosity is the true specific gravity. Divide and seek.

  Patent Document 2 aims to provide an efficient measurement method such as a measurement time and the like with high accuracy in the porosity of a porous body having a large pore diameter and a complicated surface shape. The sample surface water is removed by sandwiching the sample with a porous water-absorbing material containing a predetermined appropriate amount of water, and the sample is then suspended from above in a water tank placed on a balance. The apparent volume of the sample is calculated by dividing the weight increment displayed on the balance by the specific gravity of water, and the apparent specific gravity of the sample is calculated by dividing the dry weight of the sample by the apparent volume. .

  Patent Document 3 is intended to provide a cross-sectional area measuring method using a processing device that is fast and has a high processing speed for measuring the transport weight by multiplying the bulk of the conveyed material on the belt conveyor and measuring the specific gravity. It is. In this Patent Document 3, a plate that blocks the illumination light that is installed above the belt conveyor and projected onto the belt surface or the surface of the conveyed product on the belt in a straight line perpendicular to the belt traveling direction is provided. The image is input to the image pickup device from a certain position so that both the light and dark separation boundary parts separated into the surface are in the field of view, and the boundary line shape is formed on the surface of the belt when there is no conveyed object The cross section of the conveyed product is extracted by binarizing the image information surrounded by the boundary portion at the bottom of the window for masking the peripheral image created in combination and the light and dark separation boundary portion of the surface of the conveyed product.

  Japanese Patent Laid-Open No. 2004-228867 accurately grasps the belt conveyor conveyed product automatic measurement apparatus and method, and the moving speed of the belt conveyor, which can accurately measure the conveyed amount of the conveyed product conveyed on the belt conveyor. It is an object to provide a method for measuring the moving speed of a belt conveyor. In this Patent Document 4, a non-contact type distance measuring means is provided that has a gap on a belt conveyor that conveys an amorphous solid material and measures the distance to a plurality of positions that cross the surface of the material. The distance to the surface of the raw material is measured at minute time intervals, the surface height at each position of the solid raw material is obtained, the moving speed of the belt conveyor is measured, and the surface of the solid raw material on the belt conveyor is measured using the surface height. The solid material stacking shape is determined by calculating the coordinates of the respective positions, and the material transport volume is obtained from the shape of the belt conveyor in an empty state.

JP 62-269040 A Japanese Patent Laid-Open No. 62-134541 JP 2000-304523 A JP 2004-144463 A

In the techniques of Patent Documents 1 and 2, the apparent specific gravity of the sample is obtained, but for that purpose, the steps of sample collection, drying, film coating, and buoyancy measurement are necessary, and measurement takes time. For example, it is difficult to quickly measure in seconds. In the techniques of Patent Documents 3 and 4, although the transport amount (transport weight) of the transported material transported on the belt conveyor can be obtained, the apparent specific gravity and the like can be quickly obtained for samples (materials) having various particle sizes. The fact is that we cannot find it.

  The present invention has been made in view of the above-described problems, and can be used to quickly estimate the apparent specific gravity and porosity of a granulated product from the accumulated shape of the granulated product. The purpose is to provide. Moreover, it aims at providing the control method of the granulation process which can manufacture a granulated material stably by controlling a granulation process based on the apparent specific gravity and porosity of the estimated granulated material. .

In order to achieve the above-described object, the present invention takes the following technical means.
The method for estimating the apparent specific gravity / porosity of the granulated product according to the present invention is the method of dropping the granulated product granulated in the ore granulation process onto the transporting machine and depositing it on the transporting machine. The apparent specific gravity and / or the porosity of the granulated product are estimated by measuring the shape and mass of the granulated product deposited on the transporting machine.
The control method of the granulation process of the present invention is based on the apparent specific gravity and / or porosity of the granulated product estimated using the above-described method for estimating the apparent specific gravity / porosity of the granulated product. It is characterized by controlling.

  According to the present invention, it is possible to quickly estimate the apparent specific gravity and porosity of a granulated material from the accumulated shape of the granulated material. Further, the granulated product can be stably produced based on the estimated apparent specific gravity and porosity of the granulated product.

It is a flowchart which calculates | requires apparent specific gravity, a porosity, etc. FIG. It is a schematic diagram which shows the classification effect | action by a conveyance machine, and the accumulation condition of the granulated material by a conveyance machine, (a) is a front view, (b) is a top view. It is a schematic diagram which shows the accumulation condition of the granulated material at the time of using an inclined plate. It is a schematic diagram which shows the accumulation condition of the granulated material at the time of using a sieve. (A) shows the surface shape of the deposit on the transporting machine, and (b) shows the change pattern of the particle size distribution of the granulated material falling and depositing on the transporting machine. It is the figure which showed the whole structure of the granulation apparatus. It is the schematic diagram which showed the accumulation condition of the granulated material on the belt conveyor in the case of using a seed screen. This is a top view of the seed screen and the belt conveyor. It is a figure which shows the positional relationship of a belt conveyor and a measuring device. It is a figure which shows the classification weight ratio of the size with respect to the whole raw ball weight in the experiment number 1. FIG. It is a figure which shows the deposition shape of the deposition layer of the raw ball in Experiment No. 1. It is a figure which shows the relationship between the accumulation position of a raw ball, and an average particle size. It is a figure which shows the relationship between the accumulation peak height of a raw ball, and a standard deviation. It is a figure which shows the relationship between the standard deviation of a particle size, and the porosity. It is a figure which shows the relationship between the standard deviation of the particle size of a pellet, and a filling rate. (A) It is a general view of a belt scale, (b) It is a general view of an impact flow meter (impact type mass measuring device). It is a figure which shows the procedure of the conventional method of calculation of the apparent specific gravity and porosity of a granulated material. It is a figure which shows the measurement result of the porosity by a conventional method, and the time to a measurement. It is the figure which showed the apparent specific gravity and porosity which were calculated | required by this invention, and the time to a measurement. It is the figure which showed the change of the porosity of a pellet. 1 is an overall view of a great kiln system. It is a figure which shows the path | route from the cooling equipment of a pellet to a measuring apparatus. It is a top view of a chute, a belt conveyor, and a belt scale. It is a figure which shows the state which a pellet accumulates on a belt conveyor. It is a figure which shows the relationship between the deposition position of a pellet, and an average particle size. It is a figure which shows the relationship between the deposition peak height of a pellet, and a standard deviation. It is a figure which shows the relationship between the standard deviation of the particle size of the pellet in a modification, and a filling rate. It is a figure which shows the apparent specific gravity calculated | required in the modification, the porosity, and the time to a measurement. It is a figure which shows the change of the porosity of the pellet calculated | required in the modification.

A method for estimating the apparent specific gravity / porosity of the granulated product of the present invention and a method for controlling the granulation process will be described.
The ore needs to be made into a lump of a predetermined size depending on the purpose of use such as calcination, calcination, reduction, and compounding. There is a granulation process as a process for turning the ore into a lump of a predetermined size.
In the granulation process, for example, small granular ore, water and binder are put into a rotating disk pelletizer, and these raw materials (ore, water, binder) are rolled on the disk pelletizer, thereby producing ore (raw material). ) Into a lump of a predetermined size. Hereinafter, the ore (raw material) having a predetermined size in the granulated product process is referred to as a granulated product.

In the rolling granulation process in which such ore is rolled to produce a granulated product, the sizes of the individual granulated products produced vary. It is known that the particle size distribution of granules (the abundance ratio of the number of granules of each particle size) can be regarded as a normal distribution (Chemical Engineering Handbook 3rd Edition, p850).
In a granulation process such as a rolling granulation process, the granulated material formed into a lump of a predetermined size is placed on a conveyor such as a belt conveyor or a pallet truck and sent from the granulation process to the lower process. It is done.

  For example, after the granulated product produced by the granulation process is transported on the upper belt conveyor, it is dropped from the upper belt conveyor to the lower belt conveyor, and the granulated material deposited on the lower belt conveyor is transported toward the lower process. To do. Alternatively, the granulated product manufactured by the granulation process is deposited on a metal pallet cart, and the granulated product is transported by running the pallet cart toward the lower process.

In the present invention, the apparent specific gravity and the porosity of the granulated product are estimated by paying attention to the state of the granulated product deposited on the transporting machine. FIG. 1 is a view showing a flowchart of a method for estimating an apparent specific gravity and a porosity of a granulated product.
As shown in FIG. 1, in estimating the apparent specific gravity of the granulated material, the accumulation shape of the granulated material deposited on a belt conveyor or the like is measured (S1). Then, the cross-sectional area of the granule deposit layer is obtained from the measured granule deposit shape (S2), and the volume of the granule deposit layer is obtained by integrating the cross-sectional area over time (S3). Further, the standard deviation of the granule particle size is obtained from the accumulated shape of the granule (S4), and the filling rate is obtained based on a database and a calibration curve prepared in advance (S5). Then, the volume (apparent volume) of the granule deposit layer after the closest packing is obtained from the measured volume and filling rate of the granule deposit layer (S6). In this embodiment, a stable filling structure with high reproducibility is referred to as closest packing.

Further, the mass of the granulated material deposited layer deposited on the belt conveyor or the like is measured (S7). Based on the mass of the granulated material deposited layer and the apparent volume of the granulated material deposited layer, The apparent specific gravity is obtained (S8).
On the other hand, in estimating the porosity of the granulated product, after acquiring the raw material composition and chemical analysis data of the granulated product (S10), based on the acquired data, the true specific gravity formula of the granulated product is used. The true specific gravity of the granules is calculated (S11). Then, the porosity of the granulated product is obtained from the true specific gravity of the granulated product and the apparent specific gravity of the granulated product (S12).

First, the flow from S1 to S4 shown in FIG. 1, that is, measurement of the shape of the granulated material, calculation of the cross-sectional area of the granulated material deposit layer, calculation of the volume of the granulated material deposit layer, calculation of the standard deviation The method will be described in detail.
FIGS. 2A and 2B illustrate a situation where the granulated product is dropped from the upper belt conveyor to the lower belt conveyor.

As shown in FIG. 2, the upper belt conveyor 1 conveys the granulated material G in the right and left direction of the paper surface, and the lower belt conveyor 2 conveys the granulated material G in the vertical direction of the paper surface. The conveyance direction of the upper belt conveyor 1 and the conveyance direction of the lower belt conveyor 2 are orthogonal to each other.
In the transporting machine 3 including the upper belt conveyor 1 and the lower belt conveyor 2, for example, a group of granulated materials in which the sizes of the granulated materials are “large”, “medium”, and “small” are mixed. Suppose that it was dropped from the belt conveyor 1 to the lower belt conveyor 2.

  The large granulated product G1 having a large granulated product has a large inertia force and thus jumps greatly, and easily lands on the lower belt conveyor 2 at a position farthest from the tip of the upper belt conveyor 1. . In addition, the small granulated product G2 having a small size of granulated material has a small inertial force and is greatly affected by air resistance and the like, so that it is immediately decelerated. On the lower belt conveyor 2, the upper belt conveyor It is easy to land at a position closest to the tip of 1. Further, the middle granulated product G3 having the size of the granulated product of “medium” is likely to fall on the lower belt conveyor 2 to a position between the large granulated product G1 and the small granulated product G2.

  That is, when the position closest to the upper belt conveyor 1 is the origin O on the lower belt conveyor 2, the small granulated material G2 is deposited on the side closer to the origin O, and the large granulated material is located on the side farthest from the origin O. G1 is deposited, and the intermediate granulated product G3 is deposited on the central side in the width direction. In other words, on the lower belt conveyor 2, a deposition layer classified from small grains (fine grains) to large grains (coarse grains) is formed along the traveling direction before the granulated product falls.

In addition, as shown in FIG. 3, in the conveyance machine 3 which drops a granulated material from the upper stage belt conveyor 1 to the lower stage belt conveyor 2, the upper stage belt conveyor 1 may incline. The angle between the inclined upper belt conveyor 1 and the horizontal direction is often 5 to 50 degrees, and if it is larger than the angle of repose of the granulated product, the granulated product drops and moves by gravity, so it is the same as FIG. Under such circumstances, the granulated material accumulates on the lower belt conveyor 2. That is, as shown in FIG. 3, even when the upper belt conveyor 1 is inclined, the small granulated material G2 is deposited on the lower belt conveyor 2 on the side closest to the upper belt conveyor 1, The large granulated product G1 is deposited on the farthest side, and the intermediate granulated product G3 is deposited between the small granulated product G2 and the large granulated product G1.
As shown in FIG. 4, when the granulated material is transported by the transporting machine 3, a sieving member 4 may be employed instead of the upper belt conveyor 1. When the sieve member 4 is employed, the sieve member 4 is made of, for example, a plate material, and a sieve mesh is formed on the plate material.

  The sieve mesh is increased in order from the transportation source to the transportation destination. That is, in the sieve member, the sieve classification size is enlarged and arranged along the traveling direction of the granulated material group. As shown in FIG. 4, even when the granulated material is dropped from the sieve member onto the lower belt conveyor 2, the granulated material on the lower belt conveyor 2 is changed from fine particles to coarse particles along the traveling direction before dropping. It accumulates in a classified state. In addition, the sieving member may vibrate itself to carry the granulated product, or may tilt and carry the granulated product by gravity. In addition, the sieve member may be one in which rollers are installed at a predetermined interval and the granulated material is classified while being classified by the rotational force of the rollers.

Therefore, the granulated product manufactured by the granulation process can be classified along the traveling direction before dropping of the granulated product by dropping it after moving in a predetermined direction.
Now, as described above, it is known that a granulated product manufactured by an industrial-scale granulation process can be arranged according to a normal distribution in the size of the granulated product and the weight ratio of the granulated product of that size. That is, the weight ratio of the granulated product showing the average particle size of the granulated group as the population is the highest, and the size variation of the individual granulated products in the granulated group is the standard in the normal distribution. It is considered to be the same as the magnitude of the deviation. In other words, the particle size distribution of the granulated product group can be estimated if the average particle size and standard deviation of the population are obtained.

However, in the case of a granulation process in which a large amount of granulated material is continuously produced, the average particle size and standard deviation values change every moment due to the influence of disturbances such as raw material conditions used and atmospheric humidity. Even if the granule group is sampled batchwise and the particle size distribution is measured, it is actually only a partial sampling in terms of space and time, and there is always doubt about the representativeness of the measurement results.
Therefore, the inventors have verified from various angles, and the characteristics that the granulated material is classified and deposited when it falls onto the transporting machine 3 such as a belt conveyor, and the characteristic feature that the granulated material group follows a normal distribution. We focused on both the particle size distribution and found out that it was estimated from the shape of the deposited surface of the granulated particles dropped on the transporting machine.

FIG. 5A illustrates the surface shape (deposition shape) of the granulated material group (granulated material accumulation layer) accumulated on the lower belt conveyor 2. For convenience of explanation, the deposition shape indicated by the solid line in FIG. 5A is “deposition shape A”, the deposition shape indicated by the dotted line is “deposition shape B”, and the deposition shape indicated by the two-dot chain line is “deposition shape C”. And
The accumulated shape indicates the outline of the granulated material accumulated on the lower belt conveyor 2. Specifically, the accumulated shape refers to the ridge line at the top of the accumulated layer when the granulated material accumulated on the lower belt conveyor 2 is viewed from the front (downstream in the traveling direction) of the lower belt conveyor 2. It is.

  As shown in FIG. 5 (a), the position of the top of the deposited shape A (the portion where the granulated material is most deposited), that is, the “deposition peak position” is slightly on the left side from the center in the width direction of the lower belt conveyor 2. It is shifted and is the same as the position of the top of the deposited shape C. Thus, since the deposition peak positions of the accumulation shape A and the accumulation shape C are the same position with respect to the lower belt conveyor 2, the particle size of the granulation material of the accumulation shape A and the granulation material of the accumulation shape C The diameter is considered to be the same.

  Now, FIG.5 (b) shows the distribution map of the particle size and weight ratio of a granulated material. The first distribution to the third distribution are distributions of deposits of any one of the deposition shapes A, B, and C shown in FIG. As shown in FIG. 5 (b), since the first distribution and the second distribution have the same granule particle size at the peak, the granule of the deposited shape A having the same deposition peak position, or It can be inferred that it is one of the granulated products of the deposited shape C.

  Here, when the spread of the accumulation shape A and the accumulation shape C shown in FIG. 5A with respect to the lower belt conveyor 2 is seen, the accumulation shape C is larger than the accumulation shape A in the width direction of the lower belt conveyor 2. Has spread. In other words, the height of the deposition layer at the deposition peak position of the deposition shape C (the rising height of the deposition shape C) is lower than the height of the deposition layer at the deposition peak position of the deposition shape A.

  On the other hand, as shown in FIG. 5B, the weight ratio at the peak of the first distribution is smaller than the weight ratio at the peak of the second distribution. Therefore, among the first distribution and the second distribution, the first distribution having a small weight ratio at the peak is considered to correspond to the deposited shape C having a low height of the deposited layer, and the second weight ratio having the large weight ratio at the peak. The distribution is considered to correspond to the deposition shape A in which the height of the deposition layer is high.

  Further, as shown in FIG. 5A, the position of the top of the deposition shape B (deposition peak position) is shifted slightly to the left compared to the position of the top of the deposition shape A and the deposition shape C (deposition peak position). Therefore, it is considered that the particle size of the granulated product of the deposition shape B is larger than the deposition shape A and the deposition shape C. Further, the height of the deposition layer at the deposition peak position of the deposition shape B is the same as the height of the deposition layer at the deposition peak position of the deposition shape A. Therefore, in FIG. 5B, the third distribution in which the peak of the weight ratio is the same as the second distribution and the granule size is larger than the second distribution is estimated as the distribution in the granulated product of the sediment shape B. can do.

  In summary, the granulated material is classified in the particle size along the traveling direction before dropping and is deposited on the transporting machine 3. The deposited shape (surface shape) thus obtained is deposited on the transporting machine 3. Measurement is performed to obtain the highest deposition position (deposition peak position), and the deposition peak height (deposition height of the deposition shape) at the deposition peak position is obtained. By comparing the distribution showing the particle size and weight ratio of the prepared granulated product, the relationship between the deposition peak position and the average particle size of the granulated product and the relationship between the deposition peak height and the standard deviation can be obtained. That is, the state (deposition peak position, accumulation peak height, average particle size, standard deviation) of the granulated material group (granulated material accumulation layer) accumulated on the lower belt conveyor 2 can be obtained.

In the measurement of the accumulation shape of the granulated material on the transporting machine, a laser beam is applied to the transporting machine using a measuring instrument, and the irradiated laser light is imaged by an imaging means, and then triangulation method is used. The shape may be obtained according to the principle, or the distance from the measuring instrument to the granulated product is obtained by receiving the laser beam reflected from the granulated product (distance measuring method by TOF method), and the measurement is performed based on this distance. May be. Thus, by using a non-contact type measuring instrument, the distance to the object can be measured without destroying the shape of the deposited surface. In addition, by irradiating laser light at the moment when it is dropped or deposited in the width direction of the transporting machine, the accumulated shape is averaged per unit length or per unit elapsed time of the granulated group on the transporting machine. It is desirable to be able to obtain

For example, when the granulated material that has accumulated due to the influence of shaking or vibration during movement of the transporting machine rolls, the highest deposition position or height of the deposition surface may change. It is possible to measure the granularity of the granulated material even in an environment where the above-mentioned disturbance influence is complicated (in an environment where there is shaking or vibration during movement of the transporting machine). is there.
In addition, the particle size distribution having the deposition peak position and the deposition peak height, that is, the particle size distribution as shown in FIG. 5, is performed in advance by a granulation process, and the granulated product granulated by the granulation process is dropped on a transport machine. Thus, a calibration curve is created, and by using this calibration curve, the deposition peak position and the deposition peak height are respectively converted into an average particle size and a standard deviation. The calibration curve is created by, for example, actually measuring a deposition peak position and a deposition peak height with an operating transporting machine, then stopping the transporting machine, and sampling a group of granules on the transporting machine. The sampled granule group is sieved to measure the particle size distribution, and the average particle size and standard deviation are obtained. By performing such an operation under a plurality of granulation conditions, the relationship between the deposition peak position and the average particle size, and the relationship between the deposition peak height and the standard deviation are obtained, and a particle size distribution is created.

Thus, the state (deposition peak position, accumulation peak height, average particle size, standard deviation) of the granulated material accumulation layer can be obtained by actually measuring the accumulation shape (surface shape).
Based on FIGS. 6 to 13, the actual operation for measuring the shape of the granulated material, calculating the cross-sectional area of the granulated material layer, calculating the volume of the granulated material layer, and calculating the standard deviation will be described in more detail. To do.
FIG. 6 shows an example of a granulation facility for producing a granulated product for iron making.

  As shown in FIG. 6, in the granulation facility 10, ores and limestones of 1 mm or less are cut out from the raw material tank A, water and binder are mixed into these ores and limestone, and the mixture is put into a disk pelletizer 11 having a diameter of 6 m. The granulated product is manufactured by supplying and rotating the disk pelletizer 11. In the following description, a raw material (ore, limestone, binder, water) granulated with a disk pelletizer 11 is referred to as a raw ball.

The disk pelletizer 11 is connected to a transporting machine 3 that transports raw balls (granulated material), and the raw balls move to the transporting machine 3 after granulation.
As shown in FIG. 7, the transporting machine 3 includes a seed screen (sieving member) 4 that is connected to a disk pelletizer 11 installed on the upstream side and is inclined in the vertical direction, and the seed screen 4 below the seed screen 4. A belt conveyor 12 that conveys the raw balls sieved by the screen 4 is used.

  The seed screen 4 is an inclined type sieve that is classified while the angle of inclination exceeds the angle of repose of the raw ball and the raw ball rolls and drops. The inclination angle of the seed screen 4 is 20 degrees. Although this seed screen 4 has sieves for removing products with an excessively small particle size, the sieves are continuously formed on the inclined surface (slope area) for classifying the raw balls, and the raw balls fall. In some cases, inertial force and air resistance work, and the raw balls accumulate as in the above-described FIGS.

  Specifically, in the seed screen 4, 7 mm sieve meshes are continuously formed on the upstream side (upper side), and 15 mm sieve meshes are continuously formed on the downstream side (lower side). A hopper 13a for receiving raw balls of 7 mm or less is provided immediately below the 7 mm sieve mesh, and a hopper 13b for receiving raw balls of more than 15 mm is provided on the lower end side of the inclined surface of the seed screen 4. Yes. Therefore, in this seed screen 4, an excessively small (particle diameter of 7 mm or less) raw ball enters the hopper 13a, and an excessively large (particle diameter exceeds 15 mm) raw ball enters the hopper 13b. The raw balls that are incompatible with being transported to the subsequent process are removed. That is, a raw ball having a particle size of 7 mm or more and 15 mm or less falls on the belt conveyor 12.

Here, on the belt conveyor 12, raw balls having a small particle size are deposited on the side close to the upstream side (right side) of the seed screen 4, and the particle size is large on the side close to the downstream side (left side) of the seed screen 4. Raw balls accumulate. The width of the belt conveyor 12 is 800 mm.
FIG. 8 is a top view of the seed screen 4 and the belt conveyor 12.
FIG. 8A shows a case where the angle formed by the seed screen 4 and the belt conveyor 12 is 90 degrees (the seed screen 4 and the belt conveyor 12 are orthogonal to each other). FIGS. 8B and 8C are A case where the angle formed by the seed screen 4 and the belt conveyor 12 is 135 degrees is shown, and FIG. 8D shows a case where the angle formed by the seed screen 4 and the belt conveyor 12 is 45 degrees. As described above, the angle formed by the seed screen 4 and the belt conveyor 12 is the center line in the width direction of the seed screen 4 and the center line in the width direction of the belt conveyor 12 in a state in which both are viewed from above (plan view). Is the angle.

  As shown in FIG. 8A, when the seed screen 4 and the belt conveyor 12 are orthogonal to each other, the raw balls dropped from the seed screen 4 are large along the width direction of the belt conveyor 12 as described above. It accumulates in order. Here, when the seed screen 4 and the belt conveyor 12 are not orthogonal, the raw balls dropped from the seed screen 4 may not be accumulated in order of size along the width direction of the belt conveyor 12 as described above. is there. However, as confirmed by operations and experiments, as shown in FIGS. 8B to 8D, when the angle formed by the seed screen 4 and the belt conveyor 12 is 45 degrees to 135 degrees, The dropped raw balls were deposited in order of size along the width direction of the belt conveyor 12. That is, as shown in FIG. 3, the raw balls dropped onto the belt conveyor 12 in order of size.

  8A shows an example in which the scanning line of the laser light emitted from the measuring device 13 is orthogonal to the traveling direction of the belt conveyor 12, that is, the center line in the width direction of the belt conveyor 12. FIG. In other words, an example in which the scanning line of the laser light is parallel to the center line in the width direction of the seed screen 4 is shown. FIGS. 8B and 8D show examples in which the scanning line of the laser beam is parallel to the center line in the width direction of the seed screen 4. FIG. 8C shows a case where the scanning line of the laser beam is parallel to the center line in the width direction of the belt conveyor 12. In any of the cases shown in FIGS. 8A to 8D, the accumulation shape of the raw balls on the belt conveyor 12, that is, the state of the accumulation layer could be measured appropriately.

Next, a method for calculating the state (deposition peak position, deposition peak height, cross-sectional area, volume) of the raw ball deposition layer (granulated material deposition layer) using a measuring instrument 13 such as a laser distance meter will be described.
As shown in FIG. 9, a measuring device 13 (laser distance meter) is installed above the belt conveyor 12. The scanning direction of the laser light of the laser distance meter is as shown in FIG.
First, in a state where the belt conveyor 12 is viewed from the front (downstream side in the traveling direction) of the belt conveyor 12, an origin O (reference point) is determined, the width direction of the belt conveyor 12 is set to the X-axis direction, and the belt conveyor 12 A direction (direction orthogonal to the X axis) orthogonal to the upper surface (surface on which the raw ball is placed) is defined as the Y axis direction. The origin O is preferably set on the same plane as the upper surface of the belt conveyor 12. In addition, the installation position of the laser distance meter is represented by a coordinate system and is defined as a position (Xf, Yf). The laser rangefinder repeats scanning and ranging while the sensor unit rotates. For example, LX-04 manufactured by Hokuyo Electric Co., Ltd. is used.

In the laser distance meter, as measurement information, for example, an angle β [°] between an axis passing through the sensor unit and parallel to the X axis and the vertical component of the laser light, and a distance D from the sensor unit to the raw ball are output. Thereby, arbitrary measurement coordinates (Xm, Ym) by the laser distance meter can be obtained by the following equation.
Xm = Xf + D × cos (π × β / 180)
Ym = Yf−D × sin (π × β / 180)
Thus, by measuring a plurality of measurement coordinates (Xm, Ym), the deposition peak position and the deposition peak height can be obtained.

In addition, you may set so that the range of the scanning line of a laser rangefinder may be settled in the width | variety of the belt conveyor 12. FIG. Moreover, the more the laser distance meter is installed at a position away from the belt conveyor 12,
Although the field of view for measuring the accumulation shape of the raw ball can be enlarged by the laser distance meter, if the laser distance meter is too far away from the belt conveyor 12, the minimum measurement angle by the laser distance meter (for example, LX-04 In some cases, the measurement interval becomes too large due to about 0.35 °). On the other hand, if the laser distance meter is too close to the belt conveyor 12, there may be a case where a blind spot portion is generated and measurement cannot be performed depending on the accumulation state of the raw balls. Therefore, it is necessary to set the distance between the laser distance meter and the belt conveyor 12 appropriately. For example, when a raw ball is dropped from the seed screen 4 and transported by the belt conveyor 12 at 80 t / hour (1 hour) and the width of the belt conveyor 12 is set to 0.8 m, the laser distance meter and the belt conveyor The distance to 12 is set to 0.5 m. However, the distance between the laser distance meter and the belt conveyor 12 may be set appropriately depending on the status of the raw balls accumulated on the belt conveyor 12 and the performance of the laser distance meter, and is not limited to the above.

  As described above, since the measurement coordinates (Xm, Ym) can be obtained based on the distance to the raw ball by the laser distance meter, based on the measurement coordinates (Xm, Ym), the deposited layer of the raw ball is measured. The cross-sectional area can be determined. That is, by integrating the value of the X coordinate (Xm) of the measurement coordinates (distance from the raw ball to the upper surface of the belt conveyor 12) in the width direction of the belt conveyor 12, the cross-sectional area of the deposited layer of the raw balls can be obtained. it can. Further, the volume of the deposited layer of the raw ball can be obtained by measuring the cross-sectional area of the deposited layer of the raw ball every predetermined time and integrating the measured cross-sectional area. That is, the volume of the deposited layer of the raw balls can be obtained by measuring the cross-sectional area of the deposited layer of the raw balls every predetermined time and performing time integration corresponding to the transport speed.

Next, a method for estimating the standard deviation of the raw balls based on the shape of the raw balls deposited (deposition peak position, deposition peak height) will be described.
Using the disk pelletizer 11 of the granulation facility 10, raw balls are manufactured at a production rate of 80 t / hour, and the manufactured raw balls are continuously supplied to the seed screen 4. Further, the raw balls are conveyed by the belt conveyor 12 through the seed screen 4. For example, the conveyance speed of the belt conveyor 12 is set to 50 m / min. While the raw balls are transported by the belt conveyor 12, the shape of the raw balls deposited on the belt conveyor 12 (deposition peak position, deposition peak height) is measured using a laser distance meter. The state where the raw balls are stably flowing on the belt conveyor 12 is confirmed, and after a predetermined time, the granulation step (granulation apparatus) is stopped.

  Then, the raw balls on the belt conveyor 12 are collected through the laser distance meter. For example, the belt conveyor 12 immediately below the laser distance meter is set as a sampling start point, a location advanced 2 m downstream from the sampling start point is set as a sampling end point, and the belt conveyor 12 located between the sampling start point and the sampling end point. Collect (collect) the upper raw ball. The collected raw balls are classified with a sieve or the like, and the ratio of the classified weight of the size to the total collected raw ball weight is calculated. In addition, the average particle size and standard deviation of the collected whole raw balls are obtained.

That is, production of raw balls by a granulator, collection of raw balls whose deposition shape (deposition peak position, deposition peak height) was measured, calculation of ratio of classification weight of the size to the total weight of collected raw balls, average particle size Calculate the standard deviation.
Table 1 shows the average particle sizes and standard deviations of the experiment numbers 1 to 9. FIG. 10 shows the ratio of the classified weight of the size to the total raw ball weight in Experiment No. 1.

Next, all the measurement information when the raw balls collected on the belt conveyor 12 pass the laser distance meter is extracted, and the accumulation shape (deposition peak position, accumulation peak height) is obtained based on the extracted measurement upper part. . That is, the accumulated shape of the raw balls from the sampling start point to the sampling end point is obtained on the belt conveyor 12.
Specifically, since the conveying speed of the belt conveyor 12 is 50 m / min, the time for the raw balls to travel 2 m by the belt conveyor 12 (the time to travel from the collection start point to the collection end point) is 2.4 seconds. During this time, for example, the laser rangefinder performs one scan in 28 milliseconds, so that the measurement information for 85 times is obtained by scanning approximately 85 times while the raw ball travels 2 m. The measurement information for 85 times is averaged to obtain a deposition shape. FIG. 11 depicts the ridgeline (deposition shape) of the deposition layer of the raw ball in Experiment No. 1. Table 2 summarizes the deposition peak positions and the deposition peak heights in Experiment Nos. 1-9.

  Next, after obtaining the average particle size, standard deviation, deposition peak position, and deposition peak height, using these data, as shown in FIG. As shown in FIG. 13, the relationship between the height of the raw ball and the standard deviation is obtained. The primary approximate line shown in FIG. 12 is a calibration curve for obtaining the average particle size from the deposition peak position. Further, the primary approximate line shown in FIG. 13 is a calibration curve for obtaining a standard deviation (variation) from the height of the deposition peak.

In actual operation, the deposition shape of the raw balls that are continuously transported is continuously measured with a laser rangefinder, the peak position and height of the deposition peak are calculated based on the measurement information, and the calibration curve obtained in advance is calculated. Used, the average particle size and standard deviation of the raw Bose are obtained, and a series of processes are performed to output and save them.
As described above, by measuring the deposition shape (surface shape), the standard deviation of the area and volume of the granulated material deposition layer and the particle size of the granulated material can be obtained.

Next, the flow from S5 to S8 shown in FIG. 1, that is, the calculation of the filling rate, the calculation of the apparent volume of the granulated material deposition layer, the measurement of the mass of the granulated material deposition layer, the apparent specific gravity of the granulated material The calculation will be described in detail.
Now, as shown in the literature of “Effect of particle size distribution on the coordination number of spherical particle random packed layer, Hamada et al., Journal of Powder Engineering 39 (9), 2002, p656-661”, It is known that there is a certain relationship between the standard deviation of the granulated product and the spatial rate of the deposited layer, and the spatial rate can be estimated from the standard deviation. Therefore, by measuring the relationship between the standard deviation of the actual granulated material and the space ratio in advance and creating an approximate expression and database, the filling rate of the granulated material accumulation layer volume on the belt conveyor can be estimated quickly. It is possible.

Then, the apparent volume can be easily calculated by using the above-described volume of the granule deposit layer and the filling rate of the granule deposit layer. Also, if you measure the mass of the granulated deposit,
The apparent specific gravity of the granulated product can also be determined by “apparent specific gravity = mass of the granulated product deposited layer / apparent volume”. Furthermore, if the true specific gravity of the granulated product is known, the porosity of the granulated product can be obtained from the apparent specific gravity and the true specific gravity of the granulated product.

In addition, the true specific gravity (for example, the true specific gravity of the pellet) of the granulated material is often measured by JISM8717 or the like, and can be easily estimated from the mineral composition with the pellet. For example, in the case of raw pellets and dry pellets, it can be estimated from a value obtained by weighted average of the true specific gravity of raw material ores measured in advance according to the blending ratio.
Using the true specific gravity obtained in this way and the apparent specific gravity obtained from the measurement of the mass of the granulated sediment layer, the porosity is shorter than that of the prior art by “porosity = 1−apparent specific gravity ÷ true specific gravity”, It is possible to estimate quickly.

Hereinafter, the actual operation for obtaining the filling rate, apparent volume, mass, and apparent specific gravity will be described in more detail.
First, estimation of the filling rate of the granulated material deposition layer will be described. The volume of the granulated material accumulation layer described above includes the volume of each granulated material and the voids between the granulated materials, and the filling rate and void rate (void rate) are “filling rate + The porosity is 1 ”. In other words, as shown in FIG. 5, when the granule is packed in the space surrounded by the ridgeline of the granule deposit and the belt conveyor (the volume of the granule deposit including the void). Is the filling rate. For example, when the granulated product is a pellet, it can be expressed by filling rate = apparent volume (volume at the time of closest packing) ÷ pellet deposited layer volume (granulated product deposited layer volume including voids). Here, the apparent volume of the pellet (volume occupied by the pellet) is a volume measured by the volume measurement method shown in JIS-M8719.

In other words, it can be expressed by pellet apparent volume = volume of pellet deposition layer × filling rate, that is, pellet apparent volume = deposition of pellet deposition layer × (1−porosity).
In general, when particles such as pellets constitute a packed bed, it is known that the ratio of the void volume to the volume of the packed bed is affected by variations in the size of the particles. For example, in the document “Effect of particle size distribution on coordination number of spherical particle random packed layer, Tomita et al., Journal of Powder Engineering 39 (9), 2002, p656-661”, as shown in FIG. The relationship between the standard deviation of the particle size and the porosity is shown. In this embodiment, as described above, the relationship between the obtained standard deviation and the volume (pellet apparent volume) of the granulated material deposition layer was determined.

Specifically, the peak height of the deposit and the volume of the granulated material deposition layer (apparent pellet volume) were measured for 2.4 seconds. Then, the belt conveyor was stopped and all the granulated substances (for example, pellets) accumulated in the range of 2 m in length and 0.8 m in width, which are measurement target ranges, were collected. The apparent volume of the collected pellets was measured according to JIS-M8749. Such measurement was repeated a plurality of times, and the relationship between the standard deviation of the pellet particle size and the filling rate was determined. The result is shown in FIG. As shown in FIG. 15, there is a strong relationship between the standard deviation of the pellet particle size and the filling rate, and the filling rate can be estimated from the standard deviation of the pellet particle size. In this experimental example, the filling factor = 0.002X ³ + 0.152X ² −0.367X + 0.933. X is a standard deviation.

  A commercially available belt scale as shown in FIG. 16A was used for measuring the mass of the pellet. That is, the belt scale of FIG. 16 (a) is a device for measuring the mass of the granulated product when the granulated product such as pellets is transported using a transport machine, Mass can be measured continuously. In addition, the measurement of the mass of a granulated material is not limited to this, Even if it is an impact flow meter (impact-type mass measuring device) as shown in FIG.16 (b) which measures mass in the connection between conveyance apparatuses. Good.

FIG. 17 is a diagram showing a procedure of a conventional method for calculating the apparent specific gravity and the porosity of the granulated product. Calculation of apparent specific gravity and porosity in the present invention will be described while describing the conventional method shown in FIG.
As shown in FIG. 17, in the conventional method, pellets are directly collected in the granulation process, and the apparent specific gravity is measured by the method shown in JIS, that is, the following procedures (1) to (5). It was.
(1) Collect pellets once every 4 hours with no bias according to a predetermined position and method. In order to select a sample without any deviation in one sampling amount, about 5 kg of pellets are sampled three times with a sampling probe at a time.
(2) The collected pellets are spread on a vat and kept in a thermostat at 110 ° C. for 2 hours or more to dry. Place the dried pellet gently until it reaches room temperature.
(3) The surface of the pellet after cooling is confirmed by human eyes, and a pellet that does not adhere to chips and has no cracks or cracks is selected. This is to reduce an error when forming a surface film in a subsequent process. Then, when pellets corresponding to about 200 g are selected so as not to be biased, the weight of the pellets is measured and recorded.
(4) Each pellet is soaked in a sodium oleate solution prepared in advance for 20 minutes. Thereafter, the oleic acid is carefully wiped off with gauze, immersed in kerosene for 10 seconds, and then naturally dried.
(5) Put one pellet in a metal basket prepared in advance. Place the basket and pellets in a bath of distilled water, measure and record the weight, and measure the temperature of the distilled water. Then, the density is calculated from the temperature of the distilled water using a physical table.
In the conventional method, the apparent specific gravity is obtained by equation (1).
Apparent specific gravity (g / cm ³ ) = dry pellet weight (g) ÷ [dry pellet weight (g) −pellet and cage weight in water (g) + basket weight in water (g)] × density of distilled water (1) )
In the conventional method, the true specific gravity is estimated according to JISM8717. For example, the true specific gravity of the pellet (raw pellet) can be easily estimated from the mineral composition and the like. It can be estimated from a value obtained by weighting and averaging the true specific gravity of raw material ores measured in advance according to the blending ratio. Table 3 shows the true specific gravity of raw material ores and the ratio of ores measured in advance.

In this case, the true specific gravity (t / m ³ ) of the pellet is the true specific gravity of the ore A × the mixing ratio of the ore A + the true specific gravity of the ore B × the mixing ratio of the ore B + the true specific gravity of the ore C × the mixing ratio of the ore C. + True specific gravity of ore D x blending ratio of ore D + true specific gravity of ore E x blending ratio of ore E + true specific gravity of ore F x blending ratio of ore F.
When the apparent specific gravity is obtained, the true specific gravity is estimated, and the porosity is obtained by “porosity (−) = 1− (apparent specific gravity ÷ true specific gravity)”.

  The results of measuring the porosity by the conventional method and the time to measurement are summarized as shown in FIG. FIG. 18 shows the result of collecting the pellets every 30 minutes in addition to the measurement in a steady 4-hour period. As shown in FIG. 18, the variation in the measurement result of the 30 minute period is larger than that of the measurement result of the four hour period. From this, it was considered that short-period porosity measurement was necessary to stably control the pellet porosity. However, as described above, since the procedure from sampling to calculation of porosity requires time, it is difficult to measure the porosity in a cycle shorter than 4 hours as long as the conventional method is used.

On the other hand, in the present invention, the shape of the granulated material deposited is measured using a sensor such as a laser distance meter, and the cross-sectional area, volume (apparent volume) of the granulated material deposited layer, deposition peak position and deposition peak height are measured. Etc. are measured every 28 ms. The standard deviation is obtained sequentially from the height of the deposition peak. Furthermore, the filling rate of the granulated material accumulation layer can be estimated from the standard deviation of the granulated particle size by using a calibration curve as shown in FIG. Thereby, in this invention, the apparent volume (m < ³ >) of a granule deposit layer can be calculated rapidly.

Further, for example, the mass of the granulated material accumulation layer per second can be obtained by a belt scale or the like. Therefore, the apparent specific gravity (kg / m ³ ) is calculated from the apparent volume (m ³ ) of the granulated deposit and the mass (kg) of the granulated deposit determined by the belt scale using the following formula: Can be sought. In the present invention, the apparent specific gravity (kg / m ³ ) = mass (t) ÷ the volume of the granulated deposit (m ³ ) ÷ the filling rate (−).

In the present invention, the estimation of true specific gravity is the same procedure as in the conventional method. The true specific gravity of raw ore is measured in advance, and the average true specific gravity in proportion to the mass is determined by calculation according to the composition. Also in the present invention, the porosity is obtained by the porosity (−) = 1− (apparent specific gravity / true specific gravity).
FIG. 19 shows the apparent specific gravity and porosity determined by the method of the present invention, and the time until measurement. The apparent specific gravity and the porosity are average values every 10 minutes. As shown in FIG. 19, in the conventional method, the porosity is obtained every 4 hours as indicated by points P1, P2, and P3. However, in the present invention, the porosity could be obtained instantaneously. In addition, the present invention has the result that the porosity can be obtained in a few seconds, but it is the same value when compared with the value of the porosity by the conventional method, the present invention is compared with the conventional method Therefore, the measurement accuracy is not reduced. In the conventional method, it is reported about 4 hours after sampling, but in the present invention, it is reported several seconds after the measurement. Furthermore, since the measurement frequency is higher than that of the conventional method, it is possible to measure the variation in porosity that has been missed by the conventional method.

  As described above, according to the present invention, the average particle size and particle size distribution of the granulated product can be easily estimated based on the accumulated shape of the granulated product on the transporting machine. That is, in the present invention, the average particle size and the particle size distribution can be grasped in real time (for example, within one minute) as compared with the estimation of the average particle size and the acquisition of the particle size distribution by batch sampling as in the past. Moreover, since the average particle diameter etc. of a granulated material can be grasped | ascertained in a short time, the yield at the time of manufacturing a granulated material by a granulation process can also be improved. That is, the granulation process, that is, the granulation apparatus can be controlled based on the estimated average particle size, particle size distribution, and the like using the granulated product particle size estimation method described above.

In the ore granulation process, as described above, control is performed based on the estimated apparent specific gravity and porosity of the granulated product. That is, in the granulation process, the porosity is estimated in time series, and the set value in the granulation process is changed when the porosity deviates from a predetermined management value.
FIG. 20 shows the change in the porosity of the pellet. As shown in FIG. 20, the range (control value) of the porosity of the pellet was set to 24-27%. When the estimated porosity (referred to as the estimated porosity) falls below 24.5%, which is close to the lower limit value of the control value, or the estimated porosity so that the porosity of the pellet does not fall outside the control value range. When the rate exceeded 26.5, which was close to the upper limit value of the control value, the porosity was corrected. Specifically, as shown in FIG. 20, when the time is 70 minutes, the estimated porosity is 24.5%. Therefore, the operator determines that the porosity needs to be increased, and The rotational speed of the disk pelletizer for producing the balls was decreased from 8.4 rpm to 8.2 rpm by 0.2 rpm. Here, since the estimated porosity does not increase even after 10 minutes have passed since the rotational speed of the disk pelletizer is reduced to 8.4 rpm, the operator further increases the rotational speed of the disk pelletizer from 8.2 rpm. Reduced to 8.0 rpm. As a result, the estimated porosity of the pellet increased. In addition, since the estimated porosity exceeded 26.5% at a point of 180 minutes, the operator determined that it approached 27%, which is the upper limit of the control value. The rotational speed was increased from 8.0 rpm to 8.2 rpm, and the estimated porosity was below 24.5% at 230 minutes, so the disk pelletizer rotational speed was increased to increase the porosity. Was reduced from 8.2 rpm to 8.0 rpm. Furthermore, since the estimated porosity exceeded 26.5% at a point of 380 minutes, the rotational speed of the disk pelletizer was increased from 8.0 rpm to 8.2 rpm in order to reduce the porosity. As described above, the porosity of the pellets can be controlled within the control value by changing the number of rotations of the disk pelletizer when producing the raw balls in accordance with the estimated porosity.

  The granulation process is a process for granulation, and granulation is also referred to as “pelletizing.” According to the Encyclopedia Mypedia (Heibonsha, Hitachi System and Service) Solidified into a spherical shape.In the case of iron ore, a small amount of a binder and water are added to fine ore, and the particles are rolled and granulated in a drum called a pelletizer and fired at about 1100 ° C. ” Explained. In addition, in the “World Encyclopedia 2nd edition Heibonsha”, granulation is defined as “solidifying powder made of fine particles into granules. Depending on the production method and technical field of the finished granules, , Pellet pellets, granule granule, microcapsule microcapsule, etc. The terms of pelletization, pelletizing pelletization, granulation granulation, etc. are also used for granulation. Briquetting or briquetting is also a kind of granulation technology. "There is a granulation in" Granulation, Chemical Co., Ltd., issued on August 15, 1968 ", which is a specialized literature for granulation. As a practical example, “powder ore pellets” was introduced on p102, and from p107, calcination, which is a partial step of the process, is described. As described above, the granulation process includes not only rolling granulation but also firing. Therefore, a modified example to which the present invention is applied in firing iron ore pellets will be described.

  FIG. 21 shows equipment after firing (a great kiln system) in the iron ore pellet manufacturing process. As shown in FIG. 21, in the iron ore pellet manufacturing process, first, raw balls granulated with fine ore using a binder such as water are dried and fired in a great kiln system 20 to increase the strength. To produce product pellets. That is, in the great kiln system 20, pellets are produced from raw balls by drying and preheating the raw balls in a great furnace 21 of a drying and firing facility, and rolling and firing in the kiln furnace 22 while controlling the temperature. . The iron ore pellets after firing are cooled by a cooler 23 to become product pellets, which are sent to a blast furnace.

  In such a process, in order to monitor the quality of the pellets sent to the blast furnace, the particle size and porosity of the iron ore pellets are monitored in the middle of the conveyance path from the cooler 23 to the blast furnace. Here, in order to prevent pellet destruction and reducibility when used in a blast furnace, upper and lower limits are set in the porosity, and the pellet porosity is controlled within the appropriate range by controlling the pellet manufacturing conditions. It is operating.

As a method for controlling the porosity of the pellets, the rolling conditions during granulation are controlled to control the porosity of the fired pellets, or the kiln temperature control is controlled by controlling the amount of heat of the kiln burner.
FIG. 22 shows the path from the pellet cooling facility to the measuring device (laser distance meter).

  Pellets baked and rolled in the kiln furnace 22 are discharged from the kiln furnace 22, cooled to about 100 ° C. in a circular cooler 23 as a cooling facility, and then shot through a cooler feeder or the like. 24 to the belt conveyor 25. The pellets guided to the belt conveyor 25 are transported to the blast furnace while being deposited on the belt conveyor 25. The laser distance meter as the measuring device 13 is installed above the belt conveyor 25. Specifically, the laser distance meter 13 is provided on the belt conveyor 25 in the immediate vicinity of the chute 24 and is used for measuring the accumulation shape of the granulated material accumulation layer (pellet layer) accumulated on the belt conveyor 25. After measurement of the accumulation shape of the granulated deposit layer by the laser distance meter 13, the pellets are conveyed to the belt scale 26, subjected to mass measurement, and then sent to the blast furnace factory by the subsequent belt conveyor 27. In addition, about the deposition shape of the granulated material deposition layer by a laser distance meter, since it is the same as that of the method mentioned above, description is abbreviate | omitted. The production amount of iron ore pellets is 400 t / h, the speed of the belt conveyor is 50 m / min, and the width of the belt conveyor is 800 mm.

FIG. 23 is a plan view of a chute, a belt conveyor, and a belt scale.
As shown in FIG. 23, after the iron ore pellets are cooled in the cooling step (cooler or the like) 23, they are deposited on the belt conveyor 25 while sliding down the inclined chute 24. The chute 24 and the belt conveyor 25 are arranged orthogonally so that the inclination direction of the chute 24 and the traveling direction of the belt conveyor 25 are at an angle of about 90 degrees. The scanning direction of the laser distance meter 13 and the traveling direction of the belt conveyor 25 are orthogonal to each other.

  FIG. 24 shows a state where the pellets are deposited on the belt conveyor via the chute. As shown in FIG. 24, the pellets supplied from above the chute 24 move down the slope of the chute 24 by gravity. The chute 24 is installed at an angle of 20 degrees with respect to the horizontal. The pellets jump out from the lower end of the chute 24 toward the belt conveyor 25 having a width of 800 mm. Due to the influence of inertia force and air resistance, small pellets fall on the belt conveyor 25 in the vicinity of the chute 24, and large pellets fall at a position away from the chute 24. That is, the dropping principle is the same as that of the above-described raw ball in the pellet.

  That is, an iron ore pellet layer (pellet layer) that is a granulated material accumulation layer is deposited across the width direction of the belt conveyor 25, and the particle size of each pellet constituting the pellet layer is different on the belt conveyor 25. . That is, in the pellet layer on the belt conveyor 25, the particle size of the iron ore pellet on the side close to the chute 24 is small, and the particle size increases with distance from the chute 24. Also in the modified example, the accumulated shape of the pellets accumulated on the belt conveyor 25 is measured by the distance sensor 13. That is, the pellet deposition shape (deposition peak position, deposition peak height) is obtained and the standard deviation of the pellet is estimated by the same method as the raw ball described above.

FIG. 25 shows the relationship between the pellet deposition position and the average particle size, and FIG. 26 shows the relationship between the pellet deposition peak height and the standard deviation. The primary approximate line shown in FIG. 25 is a calibration curve for obtaining the average particle size from the deposition peak position. Further, the primary approximate line shown in FIG. 26 is a calibration curve for obtaining a standard deviation (variation) from the height of the deposition peak.
Next, the pellet filling rate is estimated based on the standard deviation of the pellet particle size and the filling rate. FIG. 27 is a diagram showing the relationship between the standard deviation of the pellet particle size and the filling rate. The filling factor was 0.019X ³ + 0.152X ² -0.367X + 0.883. X is a standard deviation. In addition, in the modification, since the apparatus which manufactures a pellet differs from embodiment mentioned above, the relationship between the standard deviation of the particle size of a pellet and a filling rate became a result shown in FIG.

  Similarly to the raw balls, the sectional area of the pellet deposition layer, the sectional area of the pellet deposition layer, and the mass of the pellet deposition layer are obtained. Then, similarly to the raw balls, the apparent volume (the volume after the closest packing) in the pellet deposition layer is determined from the volume of the pellet deposition layer and the filling rate. Further, the apparent specific gravity of the pellet is obtained based on the mass of the pellet deposited layer and the apparent volume of the pellet deposited layer.

  Further, the true specific gravity formula of the pellet is obtained, the true specific gravity of the pellet is calculated from the true specific gravity formula, and the porosity of the pellet is obtained from the true specific gravity of the pellet and the apparent specific gravity of the pellet. In this embodiment (modification), the true specific gravity of the pellet is obtained using the estimation formula disclosed in Japanese Patent Application Laid-Open No. 61-204344. Specifically, the true specific gravity of the pellet was determined by the true specific gravity = a + b × (T−Fe mass%) ÷ (100−LOI%). a and b are constants, and a = 2.75 and b = 3.36 were used. T-Fe is the average total iron content (%) of the raw material, and LOI is the average loss on ignition. In obtaining T-Fe and LOI, JISM8212 is obtained for the total iron content of ores constituting the pellet, and ignition loss is obtained by JISM882. For example, it is assumed that the total iron content, ignition raw material, and blending ratio in each raw material of the pellet are values shown in Table 3. In this case, the average total iron content (T-Fe) is obtained by multiplying the blending ratio of the ore (raw material) by the total iron content of each raw material. That is, when each raw material of the pellet is Table 3, the average total iron content (%) = total iron content of ore A × combination ratio of ore A + total iron content of ore B × composition ratio of ore B + total iron content of ore C x ore C blending ratio + ore D total iron x ore D blending ratio. The average loss on ignition is also calculated in the same way as for all iron.

As a result, T-Fe (average of total iron content) was 61.9% by mass, ignition loss was 2.71% by mass, and the true specific gravity (estimated value of true specific gravity) of the pellet was 4.89.
FIG. 28 shows the apparent specific gravity and porosity determined in the above-described modification, and the time until measurement. The apparent specific gravity and the porosity are average values every 5 minutes. As shown in FIG. 28, in the conventional method, the porosity is obtained every 4 hours as indicated by points P4 and P5. However, in the present invention, the porosity could be obtained instantaneously. In addition, the present invention has the result that the porosity can be obtained in a few seconds, but it is the same value when compared with the value of the porosity by the conventional method, the present invention is compared with the conventional method Therefore, the measurement accuracy is not reduced. In the conventional method, it is reported about 4 hours after sampling, but in the present invention, it is reported several seconds after the measurement. Furthermore, since the measurement frequency is higher than that of the conventional method, it is possible to measure the variation in porosity that has been missed by the conventional method.

  FIG. 29 shows changes in the porosity of the pellets obtained based on the modification. As shown in FIG. 29, the porosity range (control value) of the pellets was also set to 26.5 to 27.5% in the modified example. As shown in FIG. 29, when the time is 30 minutes, the estimated porosity is 27.3% which is a value close to the control value, so the operator determines that the porosity needs to be reduced. The firing temperature of the kiln furnace was increased from 1270 ° C. to 1290 ° C. Also, at the 230 minute point, the estimated porosity exceeded 26.7% and approached the lower limit of the control value, so the operator increased the kiln furnace firing temperature from 1290 ° C to 1270 to increase the porosity. Reduced to 0C.

As described above, the apparent specific gravity and / or porosity of the granulated product is estimated from the accumulated shape and mass of the granulated product by employing the method for estimating the apparent specific gravity and porosity of the granulated product of the present invention. be able to. Moreover, according to the control method of a granulation process, the granulated material which has a predetermined porosity can be manufactured stably.
In the embodiment disclosed this time, matters not explicitly disclosed, for example, operating conditions and operating conditions, various parameters, dimensions, weights, volumes, etc. of components deviate from the areas normally practiced by those skilled in the art. However, matters that can be easily assumed by those skilled in the art are employed.

DESCRIPTION OF SYMBOLS 1 Upper belt conveyor 2 Lower belt conveyor 3 Conveying machine 4 Sieve member 10 Granulation equipment 11 Disc pelletizer 12 Belt conveyor 20 Great kiln system 21 Great furnace 22 Kiln furnace 23 Cooler 24 Chute 25 Belt conveyor 26 Belt scale 27 Belt conveyor G Granulated product G1 Large granulated product G2 Small granulated product G3 Medium granulated product

Claims (2)

  When the granulated product granulated in the ore granulation process is dropped on a transport machine and transported while being deposited on the transport machine, by measuring the deposited shape and mass of the granulated product on the transport machine A method for estimating an apparent specific gravity / porosity of a granulated product, wherein the apparent specific gravity and / or porosity of the granulated product is estimated.   The ore granulation process is controlled based on the apparent specific gravity and / or porosity of the granulated product estimated using the method for estimating the apparent specific gravity and porosity of the granulated product according to claim 1. To control the granulation process.