Particle size distribution measurement method

Abstract

To provide a particle size distribution measurement method that can accurately calculate a total mass distribution of a mixed particle size deposit, while distinguishing the types of particles.SOLUTION: A particle size distribution measurement method includes: a step ST1 of preparing a single particle size sample for each of a first type particle and a second type particle and calculating a first particle size distribution of the single particle size samples; a step ST2 of calculating a first circularity distribution of the single particle size samples; a step ST3 of calculating a second particle size distribution of a mixed particle size deposit in which the first type and second type particles are blended; a step ST4 of calculating a second circularity distribution of the mixed particle size deposit; a step ST5 of calculating a first coefficient of a linear combination of the first circularity distribution approximating the second particle size distribution; a step ST6 of calculating a second coefficient of the linear combination of the first circularity distribution approximating the second particle size distribution; a step ST8 of, by using a surface probability model, calculating the total number distribution of the mixed particle size deposit from the second coefficient; and a step ST9 of calculating the total mass distribution of the mixed particle size deposit on the basis of the total number distribution and a mass ratio.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a method for measuring the particle size distribution of particles such as sintered ore, pellets, etc. In particular, the present invention relates to a particle size distribution measuring method capable of accurately calculating, for a mixed-grain-size deposit (a deposited particle group) containing a first type of particle (e.g., sintered ore) and a second type of particle (e.g., pellets) that are different from each other, a total mass distribution, which is the relationship between particle size classes (classifications determined by the size of the particle, which is an index indicating the degree of particle size) and the total mass ratio of particles in each particle size class of the mixed-grain-size deposit, while distinguishing between particle types. [Background technology]

[0002] Blast furnace raw materials such as coke and sintered ore are transported in a piled state on a belt conveyor and charged into a blast furnace. It is known that the particle size (an index showing the degree of particle size) of the particles that make up the raw materials affects the productivity of blast furnace operation. For this reason, it is desirable to continuously measure the particle size distribution of the raw materials during the raw material transportation process to maintain quality. Here, when the production volume of sintered ore is insufficient, pellets may be added as a supplementary raw material and transported in a mixed state with the sintered ore. In this case, it is desirable to be able to measure the particle size distribution of the sintered ore and the pellets so that they can be distinguished even if they are in the same particle size division.

[0003] The particle size of blast furnace raw materials is generally measured by taking samples (sampling) from a belt conveyor at regular intervals, dividing the samples every 4 or 8 hours, and then sieving them. Therefore, even if the particle size distribution of the raw materials changes in a short period of time due to variations in the quality of the raw materials or malfunctions of the production equipment, the time intervals are too long when measuring intermittently using a sieve after sampling, so the temporal fluctuations in the particle size distribution cannot be accurately captured.

[0004] As a method capable of continuously measuring particle diameters in a non-contact manner, for example, the method described in Non-Patent Document 1 has been proposed. The method described in Non-Patent Document 1 is a measurement method using a light-section type 3D camera in which a laser light source that emits linear laser light is integrated with an area scan camera. In the method described in Non-Patent Document 1, a moving distance detection means such as a rotary encoder in contact with the belt conveyor is used to measure the position of the upper edge of the cross section of the particles deposited on the belt conveyor with a 3D camera every time the belt conveyor advances a certain distance, thereby generating a distance image (sometimes called a 3D image or a depth image) in which the pixel value of each pixel indicates the distance from a reference position (for example, the distance from the 3D camera). In the vicinity of the boundary between the piled up particles, the irradiated laser light is interrupted and darkened, and the unevenness of the particles becomes large, so that the pixel value of the pixel area corresponding to the vicinity of the particle boundary in the distance image is likely to be different from the pixel value of the other pixel areas. In the method described in Non-Patent Document 1, this characteristic is utilized to determine the particle boundary, identify each particle, and calculate the particle size of each particle. The dimensions of the piled up particles having a part hidden by other particles are smaller than the actual dimensions. For this reason, in the method described in Non-Patent Document 1, height information of each particle (height from the bottom of the conveyor belt) that can be calculated using a 3D camera is used to preferentially extract surface particles (hereinafter referred to as "surface particles" as appropriate), and the minor axis diameter of each surface particle in the distance image when considered as an ellipse is taken as the particle size.

[0005] As a method capable of continuously measuring particle size in a non-contact manner, the methods described in Non-Patent Document 2 and Patent Document 1 have been proposed, which use a 3D camera similarly to the method described in Non-Patent Document 1. Non-Patent Document 2 and Patent Document 1 provide detailed descriptions of an edge detection method for identifying each particle and an image processing method for recognizing surface particles. Patent Document 1 in particular also describes a method for speeding up measurements.

[0006] In the method described in Non-Patent Document 2, image processing is performed on the distance image acquired for the deposited particles, surface particles in the surface layer with little overlap are extracted, the particle size of each surface particle is sorted into particle size categories determined by the mesh size of the sieve, and the number distribution of surface particles (surface number distribution) which is the relationship between the particle size category and the number of surface particles for each particle size category is calculated. In addition, in the method described in Non-Patent Document 2, the number distribution of the entire deposited particles, including not only surface particles but also hidden particles, is estimated using a surface probability model which is a model that represents the degree of appearance and visibility in the surface layer according to the particle size, that is, a model that estimates the number distribution of the entire deposited particles (total number distribution) from the number distribution of surface particles. Furthermore, in the method described in Non-Patent Document 2, the volume ratio (or mass ratio) for each particle size category is used to estimate the distribution of the mass ratio of the entire deposited particles (total mass distribution).

[0007] The inventors applied the method described in Non-Patent Document 2 to a mixed-grain deposit in which particles (coke) belonging to multiple grain size classes are mixed in a predetermined mass ratio and deposited, and conducted a confirmation test to determine whether the overall mass distribution can be accurately estimated. As a result of this confirmation test, it was found that even if the sample was a single-grained sample consisting of only particles with the same grain size, in the case of amorphous particles such as coke and sintered ore, the grain size distribution of the single-grained sample would be wider than the grain size distribution because the grain size of the surface layer particles varies depending on the particle's posture. Therefore, it was found that simply dividing the grain sizes of the surface layer particles measured with a 3D camera into grain size distributions determined by a sieve, counting the number of surface layer particles for each grain size distribution, and applying the method described in Non-Patent Document 2 would result in a blurred grain size distribution (total mass distribution) that would not accurately match the results measured using a sieve.

[0008] Therefore, the present inventors have proposed a method described in Patent Document 2, which is capable of calculating the grain size distribution of a mixed grain size deposit with high accuracy. In the method described in Patent Document 2, single-grain-size samples (samples consisting of only particles having the same grain size) are prepared for each of the multiple grain size classes to which the particles constituting the mixed-grain-size deposit belong, and the grain size of the surface layer of each single-grain-size sample is measured to calculate a first grain size distribution that indicates the relationship between the grain size and the number (or area or volume) of the particles in the surface layer of the single-grain-size sample. In addition, the grain size of the surface layer of the mixed-grain-size deposit containing particles belonging to the multiple grain size classes is measured to calculate a second grain size distribution that indicates the relationship between the grain size and the number (or area or volume) of the particles in the surface layer of the mixed-grain-size deposit. Furthermore, the calculated second grain size distribution is approximated by a linear sum of the calculated first grain size distributions, and each coefficient of this linear sum is regarded as the number ratio of different grain size classes of particles in the surface layer of the mixed-grain-size deposit when it is considered that the mixed-grain-size deposit is composed of a combination of single-grain-size samples of multiple grain size classes. Then, by using this coefficient to calculate the overall mass distribution using a procedure similar to that described in Non-Patent Document 2, it is possible to obtain a highly accurate calculation that closely matches the results of measurements using a sieve. However, the method described in Patent Document 2 does not take into consideration the calculation of the particle size distribution of a mixed-grain deposit containing different types of particles, such as sintered ore and pellets, while distinguishing between different types.

[0009] The inventors applied the method described in Patent Document 2 to a mixed-grain deposit in which a first type of particles belonging to multiple grain size divisions and a second type of particles different from the first type and belonging to one of the multiple grain size divisions are mixed in a predetermined mass ratio and deposited, and conducted a confirmation test to determine whether the overall mass distribution of each type could be accurately calculated. Specifically, a confirmation test was conducted in which sintered ore as a first type of particle belonging to a total of four particle size categories, namely, 10mm<particle size≦15mm (i.e., particle size that passes through a 15mm mesh sieve but not a 10mm sieve), 15mm<particle size≦25mm (i.e., particle size that passes through a 25mm mesh sieve but not a 15mm sieve), 25mm<particle size≦35mm (i.e., particle size that passes through a 35mm mesh sieve but not a 25mm sieve), and 35mm<particle size≦50mm (i.e., particle size that passes through a 50mm mesh sieve but not a 35mm sieve), and pellets as a second type of particle belonging to the particle size category of 10mm<particle size≦15mm, which is one of the above four particle size categories, were mixed in a predetermined mass ratio and deposited, to apply the method described in Patent Document 2 to the mixed particle size deposit. Hereinafter, in this specification, the particle size category of 10mm<particle size≦15mm to which the pellets (second type of particles) belong is referred to as "particle size category 1," the particle size category of 10mm<particle size≦15mm to which the sintered ore (first type of particles) belongs is referred to as "particle size category 2," the particle size category of 15mm<particle size≦25mm is referred to as "particle size category 3," the particle size category of 25mm<particle size≦35mm is referred to as "particle size category 4," and the particle size category of 35mm<particle size≦50mm is referred to as "particle size category 5." Particle size category 1 and particle size category 2 are the same in terms of the particle size ranges they belong to, but are given different names because they belong to different types of particles.

[0010] FIG. 1 shows an example of the result of calculating the particle size distribution (first particle size distribution) of each single particle size sample of particle size divisions 1 to 5 used in the above-mentioned confirmation test. Specifically, FIG. 1 collectively illustrates the first particle size distribution showing the relationship between the particle size and area of ​​the surface layer particles of each single particle size sample of particle size divisions 1 to 5. Also, FIG. 2 shows an example of the result of calculating the total mass distribution of the mixed particle size deposit used in the above-mentioned confirmation test. FIG. 2(a) shows the result of calculating the total mass distribution of the mixed particle size deposit mixed with 10% pellets of particle size division 1, 25% sintered ore of particle size division 2, 25% sintered ore of particle size division 3, 25% sintered ore of particle size division 4, and 15% sintered ore of particle size division 5 in mass proportions. Fig. 2(b) shows the results of calculating the overall mass distribution of a mixed particle size deposit blended in mass proportions of 20% pellets in particle size category 1, 25% sintered ore in particle size category 2, 25% sintered ore in particle size category 3, 20% sintered ore in particle size category 4, and 10% sintered ore in particle size category 5. The graph indicated with "sieve" in Fig. 2 shows data measured using a sieve (mass proportions reflecting the actual state of the blended particles), and the graph indicated with "3D" shows data calculated by the method described in Patent Document 2 using a 3D camera. As shown in Fig. 1, the first particle size distribution of pellets in particle size category 1 and the first particle size distribution of sintered ore in particle size category 2 (which is the same as particle size category 1 in terms of the range of particle sizes belonging to the particle size category) almost overlap, so that the two cannot be accurately distinguished from each other. Due to this, it was found that the total mass distribution of the mixed particle size deposit calculated by the method described in Patent Document 2 does not accurately match the result measured by a sieve, as shown in Fig. 2.

[0011] As described above, the method described in Patent Document 2 does not disclose a method for calculating the overall mass distribution of a mixed-grain deposit that contains a first type of particles, such as sintered ore, and a second type of particles, such as pellets, which are different from each other, by distinguishing between types, particularly when the first type of particles contains particles that belong to the same grain size class as the second type of particles. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] JP 2019-174155 A [Patent Document 2] Patent Publication No. 2022-172620 [Non-patent literature]

[0013] [Non-Patent Document 1] MJ Thurley, "Automated, On-line, Calibration-Free, Particle Size Measurement using 3D Profile Data", Measurement and Analysis of Blast Fragmentation: Workshop Hosted by FRAGBLAST 10 - The 10th International Symposium on Rock Fragmentation by Blasting, 2013, pp.23-32 [Non-Patent Document 2] MJ Thurley, "Three Dimensional Data Analysis for the Separation and Sizing of Rock Piles in Mining", Ph.D. Thesis, Monash University, December 2002, chapter 4, pp.27-60 Summary of the Invention [Problem to be solved by the invention]

[0014] The present invention has an objective of providing a particle size distribution measuring method that can accurately calculate the overall mass distribution, which is the relationship between the particle size divisions and the total mass proportion of particles in each particle size division of a mixed-grain-size deposit containing a first and a second type of particles that are different from each other, while distinguishing between particle types. [Means for solving the problem]

[0015] In order to solve the above problems, the present inventors have conducted intensive research with a view to improving the method described in Patent Document 2, focusing on utilizing the circularity of particles that can be calculated from a distance image obtained by the method described in Patent Document 2. Specifically, single-grain-size samples similar to the method described in Patent Document 2 were prepared for each of the first type of particles and the second type of particles, and a first circularity distribution showing the relationship between the circularity and the number of particles in the surface layer of each single-grain-size sample was calculated. In addition, a second circularity distribution showing the relationship between the circularity and the number of particles in the surface layer of the mixed-grain-size deposit in which the first type of particles and the second type of particles are blended was calculated. We then found that by approximating the calculated second circularity distribution by a linear sum of the calculated first circularity distribution, and regarding each coefficient of this linear sum as the number ratio of each particle size class of the surface layer of the mixed-grain deposit when it is considered that the mixed-grain deposit is composed of a combination of each single-grain size sample, it is possible to use these coefficients to calculate the overall mass distribution in a similar procedure to the method described in Patent Document 2, and it is possible to distinguish particle types and obtain a highly accurate calculation that closely matches the results of measurement using a sieve. The present invention has been completed based on the findings of the present inventors. The present invention provides a method (first method) that partially utilizes the coefficient (first coefficient) of the linear sum of the first particle size distributions approximating the second particle size distribution used in the method described in Patent Document 2 when calculating the coefficient (second coefficient) of the linear sum of the first circularity distributions approximating the second circularity distribution, and a method (second method) that does not utilize the coefficient of the linear sum of the first particle size distributions approximating the second particle size distribution used in the method described in Patent Document 2 when calculating the coefficient of the linear sum of the first circularity distributions approximating the second circularity distribution.

[0016] That is, in order to solve the above-mentioned problems, the present invention provides a first method in which single-grain-size samples, which are samples consisting of only particles having the same grain size, which is a grain size division determined by the grain size, are prepared for a plurality of grain size divisions for a first type of particle, and for a second type of particle that is a type different from the first type, a grain size division is prepared for one of the plurality of grain size divisions, the surface layer of each of the single-grain-size samples is imaged by changing the deposition state of the single-grain-size sample, a distance image showing the distance from a reference position to the particles in the surface layer is obtained, and the single-grain-size samples are subjected to a measurement of the distance from a reference position to the particles in the surface layer. a first particle size distribution calculation step of calculating a first particle size distribution showing the relationship between particle size and area of ​​the particles in the surface layer of the single particle size sample for each of the plurality of particle size divisions for the first type of particles, and for the one particle size division for the second type of particles, based on the distance image of the single particle size sample; and a first circularity distribution showing the relationship between circularity and number of particles in the surface layer of the single particle size sample, for each of the plurality of particle size divisions for the first type of particles, and for the one particle size division for the second type of particles, based on the distance image of the single particle size sample. a first circularity distribution calculation step of calculating a circularity distribution for a particle size division; a second particle size distribution calculation step of imaging a surface layer of a mixed-grain-size deposit body in which the first type of particles belonging to the plurality of particle size divisions and the second type of particles belonging to the one particle size division are mixed, while changing the deposition state of the mixed-grain-size deposit body, acquiring a distance image showing the distance from a reference position to the particles of the surface layer, and calculating a second particle size distribution showing the relationship between the particle size and the area of ​​the particles of the surface layer of the mixed-grain-size deposit body based on the distance image of the mixed-grain-size deposit body; a second circularity distribution calculation step of calculating a second circularity distribution showing a relationship between the circularity and the number of particles in the surface layer of the mixed grain size deposit body; a first coefficient calculation step of approximating the second grain size distribution with a linear sum of the first grain size distribution for each of the plurality of grain size divisions calculated for the first type of particles and the first grain size distribution for the one grain size division calculated for the second type of particles, and calculating a first coefficient which is a coefficient of the linear sum; anda second coefficient calculation step of approximating the first circularity distribution for the one particle size range calculated for the second type of particles with a linear sum and calculating a second coefficient which is a coefficient of the linear sum; an overall number distribution calculation step of calculating from the second coefficient, using a surface probability model that estimates the number distribution of all the deposited particles from the number distribution of particles in a surface layer, an overall number distribution which is a relationship between the multiple particle size ranges of the first type of particles and the one particle size range of the second type of particles, and the overall number ratio of each of the multiple particle size ranges of the first type of particles and the one particle size range of the second type of particles in the mixed particle size deposit; and an overall mass distribution calculation step of calculating an overall mass distribution, which is a relationship between the mass ratio of the plurality of particle size divisions of the first type of particles and the mass ratio of the entire particles for each of the one particle size division of the second type of particles, based on a mass ratio of the plurality of particle size divisions of the first type of particles and the mass ratio of the entire particles for each of the one particle size division of the second type of particles, wherein the first coefficient calculation step determines only the first coefficient for a particle size division different from the one particle size division of the second type of particles among the plurality of particle size divisions of the first type of particles, and the second coefficient calculation step calculates the second coefficient under a condition that the second coefficient for a particle size division different from the one particle size division of the second type of particles among the plurality of particle size divisions of the first type of particles is proportional to the first coefficient determined in the first coefficient calculation step.

[0017] In the present invention (the first method and the second method described later), a "distance image" refers to an image in which the pixel value of each pixel indicates the distance from a reference position (for example, the distance from a distance image acquisition means), a "distance image" of a single-grained sample is an image indicating the distance from a reference position to the particles of the surface layer of the single-grained sample, and a "distance image" of a mixed-grained deposit is an image indicating the distance from a reference position to the particles of the surface layer of the mixed-grained deposit. The distance image acquisition means for acquiring a distance image is not particularly limited as long as it is a means capable of acquiring the distance to the target surface layer, and for example, a light-cutting type 3D camera in which a laser light source that emits linear laser light and an area scan camera are integrated can be mentioned. The reference position can be set to any position, and for example, the position of the distance image acquisition means can be set as the reference position. If a "distance image" can be acquired, for example, by using the method described in Non-Patent Document 2 or the like, a calculation device connected to the distance image acquisition means can perform a calculation based on the "distance image" to calculate the particle size, the number of particles, and the circularity of the particles. Furthermore, "circularity" is a value calculated based on a distance image, expressed by the following formula (1), where A is the area of ​​a particle in pixels, P is the perimeter of a particle in pixels, and π is the circularity constant. Circularity is an index that indicates that the closer the value is to 1, the closer the particle shape (shape in plan view) is to a circle. Circularity = 4π A / P 2 (1) Moreover, the "surface probability model" is synonymous with the surface probability model described in Non-Patent Document 2, and is a model that expresses the degree of appearance and visibility on the surface layer according to particle size. In other words, the surface probability model is a model that relates the number distribution of particles in the surface layer to the number distribution of all the deposited particles, and is a model that estimates the number distribution of all the deposited particles from the number distribution of particles in the surface layer. Furthermore, the term "mass ratio" refers to the value obtained by dividing the average mass per particle measured for particles belonging to one particle size division by the reference mass, where the average mass per particle measured for particles belonging to another particle size division is taken as the reference mass.

[0018] According to the first method of the present invention, in the second coefficient calculation step, the second circularity distribution of the mixed-grain-size deposit calculated in the second circularity distribution calculation step is approximated by a linear sum of the first circularity distributions obtained from each single-grain-size sample calculated in the first circularity distribution calculation step, and a second coefficient, which is a coefficient of the linear sum, is calculated. Based on the above-mentioned findings of the inventor, this linear sum coefficient can be considered to be the number ratio of particles in the surface layer belonging to the grain size division of each single-grain-size sample in the mixed-grain-size deposit. Therefore, in the subsequent steps, as in the method described in Patent Document 2, the surface probability model is used to calculate the total number distribution, which is the relationship between the grain size divisions (multiple grain size divisions of the first type of particles and one grain size division of the second type of particles) and the total number ratio of particles in each grain size division of the mixed-grain-size deposit, from the calculated second coefficient, and the total mass distribution is calculated, which is the relationship between the grain size divisions and the total mass ratio of particles in each grain size division of the mixed-grain-size deposit.

[0019] Here, in the first method according to the present invention, in the first coefficient calculation step, the second particle size distribution for the mixed-grain-size deposit calculated in the second particle size calculation step is approximated by a linear sum of the first particle size distributions obtained from the individual single-grain-size samples calculated in the first particle size distribution calculation step, and a first coefficient, which is a coefficient of the linear sum, is calculated, in the same manner as in the method described in Patent Document 2. This calculated first coefficient is used to calculate the second coefficient in the second coefficient calculation step. However, among the calculated first coefficients, the first coefficient for one particle size division of the second type of particles (the first coefficient assigned to the first particle size distribution obtained from a single particle size sample consisting of only the second type of particles belonging to the particle size division) and the first coefficient for a particle size division of the first type of particles that is the same as the particle size division of the second type of particles (the particle size range belonging to the particle size division is the same) (the first coefficient assigned to the first particle size distribution obtained from a single particle size sample consisting of only the first type of particles belonging to the particle size division) are numerically unstable and unreliable because the first particle size distributions to which the first coefficients are assigned almost overlap as described above with reference to Fig. 1. For this reason, in the first method according to the present invention, in the first coefficient calculation step, only the first coefficient for a particle size division different from the particle size division of the second type of particles is determined as the one to be actually used among the multiple particle size divisions of the first type of particles. Then, in the second coefficient calculation step, the second coefficient is calculated under the condition that the second coefficient for a particle size range different from one particle size range of the second type of particles among the plurality of particle size ranges of the first type of particles is proportional to the first coefficient determined in the first coefficient calculation step, thereby making it possible to calculate the second coefficient with high accuracy. As described above, in the first method of the present invention, the coefficient (second coefficient) of the linear sum of the first circularity distributions approximating the second circularity distribution is regarded as the number ratio of each grain size category of particles in the surface layer of the mixed-grain-size deposit when it is considered that the mixed-grain-size deposit is composed of a combination of each single-grain-size sample, and this coefficient is used to finally calculate the overall mass distribution, so that, as discovered by the inventors above, it is possible to accurately calculate the overall mass distribution by distinguishing between particle types.

[0020] In the first particle size distribution calculation step and the second particle size distribution calculation step of the first method according to the present invention described above, particle size distributions (first particle size distribution and second particle size distribution) showing the relationship between the particle size and area of ​​the surface layer particles are calculated, respectively. However, according to the knowledge of the present inventors, one parameter of the relationship shown in the particle size distribution is not necessarily limited to the area of ​​the surface layer particles, and instead, the entire mass distribution can be calculated with high accuracy even if a particle size distribution showing the relationship between the particle size and the number or volume of the surface layer particles is used. Therefore, in the first particle size distribution calculation step, instead of a first particle size distribution showing the relationship between the particle size and area of ​​the particles in the surface layer of the single-particle-size sample, a first particle size distribution showing the relationship between the particle size and number of particles in the surface layer of the single-particle-size sample may be calculated, and in the second particle size distribution calculation step, instead of a second particle size distribution showing the relationship between the particle size and area of ​​the particles in the surface layer of the mixed sediment, a second particle size distribution showing the relationship between the particle size and number of particles in the surface layer of the mixed sediment may be calculated. Alternatively, in the first particle size distribution calculation step, instead of a first particle size distribution showing the relationship between the particle size and area of ​​particles in the surface layer of the single-particle-size sample, a first particle size distribution showing the relationship between the particle size and volume of particles in the surface layer of the single-particle-size sample may be calculated, and in the second particle size distribution calculation step, instead of a second particle size distribution showing the relationship between the particle size and area of ​​particles in the surface layer of the mixed sediment, a second particle size distribution showing the relationship between the particle size and volume of particles in the surface layer of the mixed sediment may be calculated.

[0021] In addition, in order to solve the above-mentioned problem, the present invention provides a second method, which includes a first circularity distribution calculation step of preparing single-grain-size samples, which are samples consisting of only particles having grain sizes that belong to the same grain size division, which is a division determined by the grain size, for each of a first type of particles and a second type of particles that is a type different from the first type of particles, taking images of the surface layer of each of the single-grain-size samples while changing the deposition state of the single-grain-size samples, obtaining a distance image showing the distance from a reference position to the particles in the surface layer, and calculating a first circularity distribution showing the relationship between the circularity and the number of particles in the surface layer of the single-grain-size sample for each of the grain size divisions of the first type of particles and the second type of particles based on the distance image of the single-grain-size sample; and a second circularity distribution calculation step of calculating a first circularity distribution showing the relationship between the circularity and the number of particles in the surface layer of the single-grain-size sample for each of the grain size divisions of the first type of particles and the second type of particles based on the distance image of the mixed-grain-size sample. a coefficient calculation step of approximating the second circularity distribution with a linear sum of the first circularity distributions calculated for each of the particle size classes of the first type of particles and the second type of particles and calculating a coefficient of the linear sum; an overall number distribution calculation step of calculating, from the coefficients, an overall number distribution which is a relationship between the particle size classes of each of the first type of particles and the second type of particles and a number ratio of the entire particles for each of the particle size classes of the first type of particles and the second type of particles in the mixed-grain-size deposit body, using a surface probability model which estimates a number distribution of the entire particles deposited from the number distribution of the particles in the surface layer; and an overall mass distribution calculation step of calculating, based on the overall number distribution and a mass ratio for the particle size classes of the first type of particles and the second type of particles, an overall mass distribution which is a relationship between the mass ratio of the entire particles for each of the particle size classes of the first type of particles and the second type of particles.

[0022] According to the second method of the present invention, in the coefficient calculation step, the second circularity distribution of the mixed grain size deposit calculated in the second circularity distribution calculation step is approximated by a linear sum of the first circularity distributions obtained from each single grain size sample calculated in the first circularity distribution calculation step, and the coefficient of the linear sum is calculated. Based on the above-mentioned knowledge of the inventor, the coefficient of this linear sum can be considered to be the number ratio of the particles of the surface layer belonging to the grain size class of each single grain size sample in the mixed grain size deposit. Therefore, in the total number distribution calculation step, as in the method described in Patent Document 2, a surface probability model is used to calculate the total number distribution, which is the relationship between the grain size class (the grain size class of the first type and the grain size class of the second type of particles) and the total number ratio of the particles of each grain size class of the mixed grain size deposit, from the calculated coefficient, and in the total mass distribution calculation step, the total mass distribution, which is the relationship between the grain size class and the mass ratio of the particles of each grain size class of the mixed grain size deposit, is calculated. Therefore, it is possible to accurately calculate the total mass distribution by distinguishing the types of particles. Effect of the Invention

[0023] According to the present invention, for a mixed-grain deposit containing a first type of particle and a second type of particle that are different from each other, the overall mass distribution, which is the relationship between the grain size divisions and the total mass proportion of particles in each grain size division of the mixed-grain deposit, can be accurately calculated while distinguishing between particle types. [Brief description of the drawings]

[0024] [Figure 1] This shows an example of the results of calculating the particle size distribution (first particle size distribution) of each single-grain-size sample in grain size categories 1 to 5 used in a confirmation test to verify the measurement accuracy of the method described in Patent Document 2 when different types of particles are blended in a mixed-grain-size deposit. [Diagram 2] An example of the results of calculating the total mass distribution of the mixed grain size deposit used in the confirmation test is shown below. [Diagram 3] FIG. 1 is a flow chart illustrating steps of a particle size distribution measuring method according to a first embodiment of the present invention. [Figure 4]FIG. 4 is an explanatory diagram for explaining steps ST1 to ST4 shown in FIG. [Diagram 5] FIG. 4 is an explanatory diagram for explaining steps ST1 to ST7 shown in FIG. [Figure 6] 1 shows the first circularity distribution of each single particle size sample calculated in Example 1-1. [Figure 7] 1 shows the linear sum of the second particle size distribution and the first particle size distribution of the mixed particle size deposit No. 1, and the linear sum of the second circularity distribution and the first circularity distribution of the mixed particle size deposit No. 1, calculated in Example 1-1. [Figure 8] 1 shows the surface number distribution, total number distribution, and total mass distribution of mixed grain size deposit No. 1 calculated in Example 1-1. [Figure 9] The results of calculating the total mass distribution of the mixed grain size deposit in Example 1-1 are shown below. [Figure 10] Of the first particle size distributions of each single particle size sample shown in Figure 1, the first particle size distributions f1(x) and f2(x) are integrated into the first particle size distribution f12(x) shown in Figure 1. [Figure 11] The linear sum of the second particle size distribution and the first particle size distribution of the mixed grain size deposit No. 1, which is the same as Example 1-1, calculated in Example 1-2, and the linear sum of the second circularity distribution and the first circularity distribution of the mixed grain size deposit No. 1, which is the same as Example 1-1, are shown. [Figure 12] The surface number distribution, total number distribution, and total mass distribution of mixed grain size deposit No. 1 calculated in Example 1-2 are shown. [Figure 13] The results of calculating the total mass distribution of the mixed grain size deposit in Example 1-2 are shown below. [Figure 14] FIG. 4 is a flow chart illustrating steps of a particle size distribution measuring method according to a second embodiment of the present invention. [Figure 15] 1 shows the linear sum of the second circularity distribution and the first circularity distribution of the mixed grain size deposit calculated in Example 2-1. [Figure 16] 3 shows the surface number distribution, total number distribution, and total mass distribution of the mixed grain size deposit calculated in Example 2-1. [Figure 17] The results of calculating the total mass distribution of the mixed grain size deposit in Example 2-1 are shown below. [Figure 18] 13 shows the linear sum of the second circularity distribution and the first circularity distribution of the mixed grain size deposit calculated in Example 2-2. [Figure 19] The surface number distribution, total number distribution, and total mass distribution of the mixed grain size deposit calculated in Example 2-2 are shown. [Figure 20] The results of calculating the total mass distribution of the mixed grain size deposit in Example 2-2 are shown below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, with reference to the accompanying drawings as appropriate, embodiments (first to fourth embodiments) of the present invention will be described, taking as an example a case where the first type of particles are sintered ore and the second type of particles are pellets.

[0026] First Embodiment The first embodiment corresponds to the first method according to the present invention. That is, the method according to the first embodiment is a method in which, when calculating the coefficient (second coefficient) of the linear sum of the first circularity distribution approximating the second circularity distribution, the coefficient (first coefficient) of the linear sum of the first particle size distribution approximating the second particle size distribution used in the method described in Patent Document 2 is partially utilized.

[0027] Fig. 3 is a flow diagram that illustrates the steps of the particle size distribution measuring method according to the first embodiment. Fig. 4 is an explanatory diagram that illustrates steps ST1 to ST4 illustrated in Fig. 3. Fig. 5 is an explanatory diagram that illustrates steps ST1 to ST7 illustrated in Fig. 3. As shown in Fig. 3, the particle size distribution measuring method according to the first embodiment includes steps ST1 to ST9. Each step will be described below in order. In the first embodiment, an example will be described in which particles belonging to four particle size divisions are blended as sintered ore, which is a first type of particles, and particles belonging to one of the four particle size divisions are blended as pellets, which is a second type of particles, to measure the particle size distribution (total mass distribution) of the mixed particle size laminate. However, the present invention is not limited to this, and can also be applied to a mixed particle size laminate in which sintered ore belonging to two, three, or five or more particle size divisions is blended.

[0028] <Process ST1> In step ST1 (corresponding to the first particle size distribution calculation step of the first method according to the present invention), single particle size samples, which are samples consisting of only particles having the same particle size, are prepared for four particle size classes for sintered ore and for one particle size class for pellets. It is possible to know in advance what particle size classes the particles belong to in a mixed particle size laminate in which sintered ore belonging to four particle size classes and pellets belonging to one particle size class are blended (i.e., particles of various particle sizes are blended). In the first embodiment, in order to measure the particle size distribution of a mixed particle size laminate in which sintered ore belonging to four particle size classes and pellets belonging to one particle size class are blended at an arbitrary mass ratio, single particle size samples are also prepared for four particle size classes for sintered ore and for one particle size class for pellets, just like the mixed particle size laminate. Specifically, in the first embodiment, as in the above-mentioned confirmation test described with reference to FIG. 1 and FIG. 2, pellets belonging to particle size division 1 (10 mm<particle size≦15 mm) and sintered ore belonging to particle size division 2 (10 mm<particle size≦15 mm), particle size division 3 (15 mm<particle size≦25 mm), particle size division 4 (25 mm<particle size≦35 mm), and particle size division 5 (35 mm<particle size≦50 mm) are mixed in an arbitrary mass ratio in the mixed particle size laminate. Therefore, single particle size samples are prepared for a total of five particle size divisions (particle size divisions 1 to 5). Specifically, for example, as shown in FIG. 4(a), a single particle size sample made of pellets belonging to particle size division 1 is prepared in a tray T. Similarly, as shown in FIG. 4(b), a single particle size sample made of sintered ore belonging to particle size division 2 is prepared in a tray T. Although not shown in the drawings, one tray T full of single particle size samples made of sintered ore belonging to particle size classes 3 to 5 is also prepared.

[0029] In step ST1, the distance image acquisition means (in this embodiment, a 3D camera 1 using a light cutting method using a linear laser light L shown in Fig. 4(a) and Fig. 4(b)) arranged above each single-particle-size sample of the five particle size divisions 1 to 5 is used to repeatedly capture images of each single-particle-size sample while changing the deposition state of the single-particle-size sample to acquire distance images, and a calculation device (not shown) connected to the distance image acquisition means performs calculations to repeatedly measure the particle size and area of ​​the surface layer particles of each single-particle-size sample. When acquiring the distance images, the tray T is moved relative to the 3D camera 1 in a direction (direction perpendicular to the paper surface of Fig. 4(a) and Fig. 4(b)) perpendicular to the direction in which the linear laser light L, which is the light cutting line, extends (the left-right direction in Fig. 4(a) and Fig. 4(b)). In the first embodiment, the minor axis diameter of the surface layer particles in the distance image when the surface layer particles are regarded as ellipses is used as the particle size of the surface layer particles. The deposition state may be changed by mixing and stirring that occurs when each single-particle-size sample is transferred between the tray T and another container C. It is preferable that the number of repetitions of the measurement of the particle size and area of ​​the surface layer particles of each single-particle-size sample is the same. As a result, as shown in FIG. 5(a), a first particle size distribution showing the relationship between the particle size (x) and area of ​​the surface layer particles of the single-particle-size sample is calculated for each of the five particle size ranges 1 to 5. Specifically, the particle size and area of ​​the surface layer particles of each single-particle-size sample are repeatedly measured, for example, ten times, and the areas of the surface layer particles measured each time are tallied for each particle size range at a predetermined interval (for example, 5 mm interval), and the first particle size distribution is calculated from the sum or average of the areas of the ten measurements. In FIG. 5(a), f 1 (x)~f 5 (x) is the first particle size distribution calculated for the single particle size samples of particle size classes 1 to 5, respectively.

[0030] <Process ST2> In step ST2 (corresponding to a first circularity distribution calculation step in the first method according to the present invention), a first circularity distribution indicating the relationship between the circularity (x') and the number of surface particles of the single particle size sample is calculated for each of the five particle size ranges 1 to 5 based on the distance image of each single particle size sample of particle size ranges 1 to 5 acquired in step ST1. The circularity is a value expressed by the following formula (1), where A is the area of ​​the particle in pixel units calculated based on the distance image, P is the perimeter of the particle in pixel units, and π is the circularity constant. Circularity = 4π A / P 2 (1) Specifically, the circularity of the surface particles of each single particle size sample is repeatedly calculated based on, for example, 10 distance images corresponding to 10 measurements, and based on the circularity of the surface particles calculated for each distance image, the number of surface particles is tallied for each circularity range at a predetermined interval (for example, 0.02 interval) to calculate a first circularity distribution. In FIG. 5(b), g 1 (x')~g 5 (x') is the first circularity distribution calculated for the single particle size samples of particle size divisions 1 to 5, respectively.

[0031] <Process ST3> In step ST3 (corresponding to the second particle size distribution calculation step in the first method according to the present invention), a distance image acquisition means (in this embodiment, a 3D camera 1 using a light cutting method with linear laser light L shown in FIG. 4(c)) is used above a mixed-particle-size laminate in which sintered ores belonging to four particle size classes 2 to 5 and pellets belonging to one particle size class 1 are mixed in an arbitrary mass ratio, and the deposition state of the mixed-particle-size deposit is repeatedly photographed to obtain distance images, and a calculation device (not shown) connected to the distance image acquisition means performs calculations to repeatedly measure the particle size and area of ​​the surface layer particles of the mixed-particle-size deposit. In the first embodiment, the minor axis diameter of the surface layer particles in the distance image when they are regarded as ellipses is used as the particle size of the surface layer particles. As in the case of single-grain samples, when a mixed-grain sediment is piled up in tray T and the grain size and area of ​​the surface grains are measured, the change in the pile condition can be made by the mixing and stirring that occurs when the mixed-grain sediment is transferred between tray T and another container C. The number of repeated measurements of the grain size and area of ​​the surface grains of the mixed-grain sediment does not necessarily have to be the same as the number of repeated measurements of each single-grain sample. When measuring the particle size and area of ​​surface particles of a mixed-grain deposit accumulated and transported on a belt conveyor, the measurements can be repeated assuming that different pile states of mixed-grain deposits mixed in the same mass ratio are developed on the belt conveyor. This allows the calculation of a second particle size distribution F(x) that indicates the relationship between the particle size (x) and area of ​​the surface layer particles of the mixed-grain sediment, as shown in Fig. 5(a). Specifically, the particle size and area of ​​the surface layer particles of mixed grain size are repeatedly measured, for example, 40 times, and the areas of the surface layer particles measured each time are tallied for each particle size range at a predetermined interval (for example, 5 mm interval), and the second particle size distribution F(x) is calculated from the sum or average of the areas of the 40 measurements.

[0032] <Process ST4> In step ST4 (corresponding to the second circularity distribution calculation step of the first method according to the present invention), a second circularity distribution showing the relationship between the circularity (x') and number of surface particles of the mixed-grain-size deposit body is calculated based on the distance image of the mixed-grain-size deposit body acquired in step ST3. Specifically, the circularity of the surface particles of the mixed grain size deposit is repeatedly measured, for example, 40 times, and based on the circularity of the surface particles measured each time, the number of surface particles is tallied for each circularity range at a predetermined interval (for example, 0.02 interval), and a second circularity distribution G(x') as shown in Figure 5(b) is calculated.

[0033] <Process ST5> In step ST5 (corresponding to the first coefficient calculation step of the first method according to the present invention), in order to quantify the extent to which the surface layer particles of each grain size division 1 to 5 appear in the second grain size distribution F(x) of the mixed grain size sediment body, as shown in FIG. 5(a), the second grain size distribution F(x) of the mixed grain size sediment body is divided into the first grain size distributions f(x) for each of the five grain size divisions 1 to 5. i (x) (i=1,2,3,4,5) linear sum Σa i f i (x) is approximated, and the first coefficient a i The approximation using a linear sum can be performed using a known approximation method such as the least squares method. In step ST5, the first coefficient a for the particle size division 2 to 5 of the sintered ore that is different from the particle size division 1 of the pellet is iIn the first embodiment, the particle size classification 2 of the sintered ore is a particle size classification of 10 mm<particle size≦15 mm, and the particle size classification 1 of the pellets is also a particle size classification of 10 mm<particle size≦15 mm, and the particle size classifications are the same (the particle size ranges belonging to the particle size classification are the same). Of the particle size classifications 2 to 5 of the sintered ore, the particle size classifications different from the particle size classification 1 of the pellets are the particle size classifications 3 to 5. For this reason, in step ST5, the calculated first coefficient a i (i=1~5) The first coefficient a for particle size categories 3~5 3 , a 4 , a 5 Only confirm.

[0034] <Process ST6> In step ST6 (corresponding to the second coefficient calculation step of the first method according to the present invention), in order to quantify the extent to which the circularity of the surface layer particles of each grain size division 1 to 5 appears in the second circularity distribution G(x') of the mixed grain size sediment body, as shown in FIG. 5(b), the second circularity distribution G(x') of the mixed grain size sediment body is divided into the first circularity distributions g(x') for each of the five grain size divisions 1 to 5. i Linear sum of (x')(i=1,2,3,4,5) Σb i ·g i (x') and the second coefficient b i Calculate. In this case, the second coefficient b for the particle size division of the sintered ore, which is different from the particle size division of the pellet, is i , i.e., the second coefficient b 3 ~b 5 is the first coefficient a determined in the second coefficient step ST5 3 ~a 5 The second coefficient b i That is, let k be the proportional constant, and b 3 =k a 3 , b 4 =k a 4 , b 5 =k a 5 Under the condition that satisfies the second coefficient b i In other words, the second coefficient b 1 , b 2and the proportionality constant k are unknowns, and a known approximation method such as the least squares method is used to determine a second coefficient b for approximating a linear sum to the second circularity distribution G(x'). 1 , b 2 and the proportional constant k are calculated. Once the proportional constant k is calculated, the first coefficient a determined in the second coefficient step ST5 is 3 ~a 5 The second coefficient b is calculated by multiplying each of the proportional constants k. 3 ~b 5 This allows all the second coefficients b i is calculated.

[0035] <Process ST7> The second coefficient b calculated in step ST6 i (i=1 to 5) can be regarded as a value (number ratio) proportional to the number of surface particles belonging to grain size class i that appear in the mixed-grain sediment. For this reason, in step ST7, each second coefficient b 1 ~b 5 are regarded as the surface number ratios, which are the number ratios of surface particles belonging to grain size classes 1 to 5 of each single-grain-size sample in the mixed-grain-size sediment body, and the surface number distribution, which shows the relationship between the grain size classes and the surface number ratios of each grain size class, is calculated for the mixed-grain-size sediment body, as shown in Figure 5(c).

[0036] <Process ST8> In step ST8 (corresponding to the total number distribution calculation step of the first method according to the present invention), the surface number distribution as shown in Figure 5(c) calculated in step ST7 and the surface probability model are used to calculate the total number distribution, which is the relationship between the grain size classification and the total number ratio of particles in each grain size classification of the mixed grain size deposit body. The surface number distribution in the first embodiment is not equal to the total number distribution, which is the distribution of the number ratio of all the deposited particles. This is because the frequency of particles appearing in the surface layer varies depending on the particle size, and the larger the particle size, the more frequently the particles appear in the surface layer, so the surface number distribution counts more large particles than the total number distribution. Therefore, in order to calculate the total number distribution, a surface probability model is required that represents the degree of likelihood of particles appearing in the surface layer or visibility according to particle size and estimates the number distribution of all the deposited particles from the number distribution of surface layer particles. The surface probability model used in the first embodiment is the same as the surface probability model described in Patent Document 2. For this reason, detailed explanation of the surface probability model and the method of calculating the overall number distribution using the surface probability model will be omitted, and only the parameter values ​​substituted into the surface probability model used in the first embodiment will be explained below.

[0037] In order to calculate the total number distribution, the surface number ratio b calculated in step ST7 is used as a parameter to be substituted into the surface probability model. i In addition, the median value D of the grain size of the grain size class i i , area ratio A in grain size category i i , the volume ratio V in particle size class i i and the height (bulk) H of the mixed grain sediment. In the first embodiment, the intermediate value D i For particle size categories 1 and 2, D 1 =D 2 =(10+15) / 2=12.5mm, for particle size categories 3 to 5, D 3 =(15+25) / 2=20mm, D 4 =(25+35) / 2=30mm, D 5 =(35+50) / 2=42.5mm. In addition, the area ratio A i is the area ratio A of pellets in particle size category 1 1 = 1, D corresponds to the area of ​​the particles in the particle size category i. i The ratio of the squares of A i =(D i / D 1 ) 2 It becomes. In addition, the volume ratio V i is the volume ratio V of pellets in particle size category 1 1 = 1, D corresponds to the volume of particles in particle size class i i The ratio of the cubes of V i =(D i / D 1 ) 3 It becomes. Furthermore, the height (bulk height) H of the mixed grain size deposit can be set to 60 mm, which is approximately the same as the height of the tray T described above, in the first embodiment. In summary, the parameter values ​​substituted into the surface probability model in the first embodiment are the values ​​shown in Table 1 below, except for the height (bulk height) H of the mixed grain size deposit body. In Table 1, the mass ratio w i is also shown. [Table 1] In step ST8, the above parameters are substituted into the surface probability model and a predetermined calculation is performed to obtain the particle size class i and the number ratio N i The total number distribution, which is the relationship between

[0038] <Process ST9> In step ST9 (corresponding to the total mass distribution calculation step of the first method according to the present invention), the total number distribution calculated in step ST8 and the mass ratio w i Based on this, the total mass distribution, which is the relationship between the grain size division i and the mass ratio of the whole particles for each grain size division i of the mixed grain size deposit, is calculated. Specifically, as shown in the following formula (1), the number ratio of all particles N i and mass ratio w i Multiply by and take the mass fraction m of the whole particles. i It is calculated as follows.

number

[0039] According to the particle size distribution measuring method according to the first embodiment described above, in step ST6, the second circularity distribution G(x') of the mixed particle size sediment body calculated in step ST4 is calculated based on the first circularity distribution g(x') of each single particle size sample calculated in step ST2. i Linear sum of (x')Σb i ·g i (x') and the second coefficient of the linear sum b i Next, in step ST7, the calculated second coefficient b i is regarded as a surface number ratio, which is the number ratio of surface layer particles belonging to the grain size division of each single grain size sample in the mixed grain size deposit, and a surface number distribution, which indicates the relationship between grain size division i and the surface number ratio for each grain size division i, is calculated. Thereafter, using a surface probability model in the same manner as in the method described in Patent Document 2, in step ST8, a total number distribution, which is the relationship between grain size division i and the number ratio of all particles for each grain size division i of the mixed grain size deposit, is calculated using the calculated surface number distribution and the surface probability model, and in step ST9, a total mass distribution, which is the relationship between grain size division i and the mass ratio of all particles for each grain size division i of the mixed grain size deposit, is calculated. Thus, the second coefficient of the linear sum, b i is considered to be the number ratio of each grain size class i of the surface layer particles of the mixed-grain sediment when the mixed-grain sediment is considered to be composed of a combination of each single grain size sample, and this second coefficient b i Since the total mass distribution is finally calculated using the above, the total mass distribution can be calculated with high accuracy by distinguishing between particle types (pellets and sintered ore).

[0040] <Example 1> Hereinafter, as Example 1 (Example 1-1 and Example 1-2), an example of the results of calculating the total mass distribution by the particle size distribution measuring method according to the first embodiment will be described.

[0041] [Example 1-1] In Example 1-1, a Sick Ranger-E50 (area scan camera pixel count: 1536 x 512, measurement speed: 35000 cross sections / sec) was used as the 3D camera 1, and the height from the bottom of the tray T to the 3D camera 1 was adjusted so that the entire tray T (width 300 mm x length 400 mm x height 60 mm) on which sintered ore and / or pellets were piled was within the field of view. The tray T was mounted on a belt-driven traveling cart, and the travel distance was detected by a rotary encoder installed on the traveling cart. The cart was set to capture one distance image when it had traveled the length of the tray T.

[0042] In step ST1 of Example 1-1, a single particle size sample of one tray T (about 7 kg) made of pellets of the above-mentioned particle size division 1 and a single particle size sample of one tray T made of sintered ore sieved into each of the above-mentioned particle size divisions 2 to 5 were prepared, and the particle size and area of ​​the surface layer particles were measured 10 times by changing the deposition state of each single particle size sample in the tray T, and the area of ​​the surface layer particles was calculated for each particle size range at 5 mm intervals. The above-mentioned FIG. 1 shows the first particle size distribution of each single particle size sample calculated in Example 1-1.

[0043] Next, in step ST2 of Example 1-1, the circularity (x') of the surface particles of each single particle size sample was repeatedly calculated based on the distance images of each single particle size sample of particle size divisions 1 to 5 obtained in step ST1 (10 distance images corresponding to 10 measurements each), and the number of surface particles for each circularity range at intervals of 0.02 was tallied to calculate the first circularity distribution of each single particle size sample. Fig. 6 shows the first circularity distribution of each single particle size sample calculated in Example 1-1. As shown in Fig. 6, in the case of pellets, which are spherical particles (corresponding to particle size category 1), the circularity peak is close to 1 and the distribution spread is narrow, but in the case of sintered ore, which is irregular particles (corresponding to particle size categories 2 to 5), the circularity peak tends to move away from 1 and the distribution tends to spread more widely as the particle size increases in the order of particle size categories 2, 3, 4, and 5.

[0044] Next, in step ST3 of Example 1-1, 10% pellets of particle size division 1, 25% sintered ore of particle size division 2, 25% sintered ore of particle size division 3, 25% sintered ore of particle size division 4, and 15% sintered ore of particle size division 5 were mixed in mass ratios in the same manner as in the confirmation test described with reference to FIG. 2(a) above, and one cup of the mixture was piled up in a tray T to obtain a mixed particle size deposit (hereinafter referred to as "mixed particle size deposit No. 1"). In addition, apart from the mixed particle size deposit No. 1, 20% pellets of particle size division 1, 25% sintered ore of particle size division 2, 25% sintered ore of particle size division 3, 20% sintered ore of particle size division 4, and 10% sintered ore of particle size division 5 were mixed in mass ratios in the same manner as in the confirmation test described with reference to FIG. 2(b) above, and one cup of the mixture was piled up in a tray T to obtain a mixed particle size deposit (hereinafter referred to as "mixed particle size deposit No. 2"). Then, in the same manner as in the case of the single-grain samples, the measurements were repeated 40 times using 3D camera 1, changing the deposition state of each mixed-grain sediment body in tray T, and the areas of surface particles for each grain size range at 5 mm intervals were tallied to calculate the second grain size distribution of each mixed-grain sediment body. Fig. 7 shows the linear sum of the second particle size distribution and the first particle size distribution of the mixed particle size deposit No. 1, and the linear sum of the second circularity distribution and the first circularity distribution of the mixed particle size deposit No. 1, calculated in Example 1-1. Fig. 7(a) shows the linear sum of the second particle size distribution and the first particle size distribution, and Fig. 7(b) shows the linear sum of the second circularity distribution and the first circularity distribution. F(x) shown by a solid line in FIG. 7(a) is the second grain size distribution of the mixed grain size deposit No. 1 calculated in step ST3 of Example 1-1.

[0045] Next, in step ST4 of Example 1-1, as in the case of the single-grain size sample, the circularity (x') of the surface particles of each mixed-grain size deposit body was repeatedly calculated based on the distance images of each mixed-grain size deposit body obtained in step ST3 (40 distance images each corresponding to 40 measurements), and the number of surface particles for each circularity range at intervals of 0.02 was tallied to calculate the second circularity distribution G(x') of the mixed-grain size deposit body as shown by the solid line in Figure 7(b).

[0046] Next, in step ST5 of Example 1-1, the second particle size distribution F(x) of each mixed particle size deposit is calculated by the least squares method, and the first particle size distribution f(x) of each single particle size sample is calculated by the least squares method. i Linear sum of (x)Σa i f i (x) and the first coefficient of the linear sum a i Calculate the first coefficient a 3 ~a 5 Only was confirmed. The dashed line in Figure 7(a) shows Σa i f i (x) is the first coefficient a calculated for the mixed grain size deposit No. 1 in step ST5 of Example 1-1. i It is a linear sum using In step ST6 of Example 1-1, the second circularity distribution G(x') of the mixed grain size deposit was calculated by the least squares method. i Linear sum of (x')Σb i ·g i (x') and the second coefficient of the linear sum b i In this case, b 3 =k a 3 , b 4=k a 4 , b 5 =k a 5 Under the condition that satisfies the second coefficient b i was calculated. The dashed line in Figure 7(b) shows Σb i ·g i (x') is the second coefficient b calculated for the mixed grain size deposit No. 1 in step ST6 of Example 1-1. i It is a linear sum using

[0047] Next, in step ST7 of Example 1-1, each second coefficient b i The surface number distribution was calculated by regarding these as the surface number ratios, which are the number ratios of surface particles belonging to grain size classes 1 to 5 in the mixed-grain sediment body. Fig. 8 shows the surface number distribution, total number distribution, and total mass distribution of the mixed-grain-size deposit No. 1 calculated in Example 1-1. Fig. 8(a) shows the surface number distribution, Fig. 8(b) shows the total number distribution, and Fig. 8(c) shows the total mass distribution. The surface number ratio on the vertical axis of the surface number distribution shown in FIG. 8(a) calculated in step ST7 of Example 1-1 is calculated by multiplying each second coefficient b i is expressed as a percentage.

[0048] Next, in step ST8 of Example 1-1, the surface number distribution shown in FIG. 8(a) and the surface probability model were used to calculate the total number distribution shown in FIG. 8(b). The total number ratio on the vertical axis of the total number distribution shown in FIG. 8(b) is the total number ratio of the whole particles that make up the mixed grain size deposit, and is a value expressed as a percentage so that the sum of the total number ratios corresponding to each grain size class is 100%. Note that when calculating the total number distribution, the mass ratio w shown in Table 1 above was used. i The values ​​of each parameter, excluding i = 1 to 5, were used, and the height (bulk height) of the mixed grain size deposit was set to H = 60 mm.

[0049] Finally, in step ST9 of Example 1-1, the total number distribution shown in FIG. 8(b) and the mass ratio w iBased on (i = 1 to 5), the total mass distribution shown in Fig. 8(c) was calculated. The total mass ratio on the vertical axis of the total mass distribution shown in Fig. 8(c) is the mass ratio of all the particles that make up the mixed-grain sediment, and is expressed as a percentage so that the sum of the total mass ratios corresponding to each grain size class is 100%. The detailed explanation of the calculation results in steps ST3 to ST8 for the mixed-grain-size deposit body No. 2 will be omitted.

[0050] Fig. 9 shows the results of calculating the overall mass distribution of the mixed-grain-size deposit in Example 1-1. Fig. 9(a) shows the results of calculation for mixed-grain-size deposit No. 1, and Fig. 9(b) shows the results of calculation for mixed-grain-size deposit No. 2. The graph shown with "Sieve" in Fig. 9 shows data measured using a sieve (mass ratio reflecting the actual state of the blended particles), and the graph shown with "3D" shows data calculated in Example 1-1 using 3D camera 1. As shown in Figure 9, compared with the result of Figure 2 calculated by the method described in Patent Document 2, the total mass distribution of the mixed-grain deposit calculated in Example 1-1 is close to the result measured using a sieve, and the total mass distribution can be calculated with high accuracy by distinguishing between particle types.

[0051] [Example 1-2] In the above-mentioned Example 1-1, in step ST5, the second particle size distribution F(x) of the mixed particle size deposit was calculated by dividing the first particle size distribution f(x) of the five single particle size samples by the first particle size distribution f(x) of the five single particle size samples. i (x) (i=1~5) linear sum Σa i f i (x) and the first coefficient of the linear sum a i is calculated. However, as shown in FIG. 1, the first particle size distribution f 1 (x) and the first particle size distribution f of sintered ore of particle size category 2 2 Since (x) and (x) are almost overlapping, when approximating with the linear sum of the first particle size distribution, the first particle size distribution f 1 (x), f 2 The first particle size distribution obtained by integrating (x) (the particle size division after integration is called particle size division 12, and the first particle size distribution after integration is called first particle size distribution f12 (x)), the first particle size distribution after integration f 12 (x) and the first particle size distribution f of particle size classes 3 to 5 3 (x)~f 5 It is also possible to approximate the second grain size distribution F(x) of the mixed grain size sediment by a linear sum of the first grain size distribution f(x) of the four grain size divisions. i (x) (i=12,3,4,5) linear sum Σa i f i (x) and the four first coefficients of the linear sum a i It is also possible to calculate (i=12,3,4,5). In Example 1-2, the first coefficient a of the linear sum is calculated in step ST5. i After calculating (i=12, 3, 4, 5), the first coefficient a 3 ~a 5 In Example 1-2, thereafter, steps ST6 to ST8 are executed in the same manner as in Example 1-1, and finally, the total mass distribution of the mixed-grain-size deposit body is calculated in step ST9.

[0052] First particle size distribution after integration f 12 As a method for obtaining (x), for example, 12 (x) is the first particle size distribution of the pellets f 1 Replace with (x) and f 12 (x)=f 1 It is possible to use (x). 12 (x) is the first particle size distribution f of sintered ore of particle size category 2 2 Replace with (x) and f 12 (x)=f 2 (x) can also be considered. 12 (x) is the first particle size distribution of the pellets f 1 (x) and the first particle size distribution f of sintered ore of particle size category 2 2 (x) is replaced with the larger value for the same granularity x, and f 12 (x) = max(f 1 (x),f 2 (x)) or replace it with the smaller one, f 12 (x)=min(f 1(x),f 2 (x)) or by replacing it with the average value, f 12 (x) = mean(f 1 (x),f 2 It is also possible to consider the following: In the example described below, the first particle size distribution f 1 (x), f 2 (x) and (x) are included in the first particle size distribution f 12 (x) = max(f 1 (x),f 2 (x)). FIG. 10 shows the first particle size distribution f of the first particle size distributions of the single particle size samples shown in FIG. 1 (x), f 2 (x) is the first particle size distribution f 12 (x) shows the primary particle size distribution after integration.

[0053] FIG. 11 shows the linear sum of the second particle size distribution and the first particle size distribution of the mixed particle size deposit No. 1, which is the same as in Example 1-1, and the linear sum of the second circularity distribution and the first circularity distribution of the mixed particle size deposit No. 1, which were calculated in Example 1-2. FIG. 11(a) shows the linear sum of the second particle size distribution and the first particle size distribution, and FIG. 11(b) shows the linear sum of the second circularity distribution and the first circularity distribution. The results shown in FIG. 11 show the linear sum of the first particle size distribution f after integration. 12 The only difference from the results shown in FIG. 7 for Example 1-1 is that the linear sum was calculated using (x), and the second particle size distribution F(x) and the second circularity distribution G(x') are the same as those shown in FIG.

[0054] FIG. 12 shows the surface number distribution, total number distribution, and total mass distribution of the mixed grain size deposit No. 1 calculated in Example 1-2. FIG. 12(a) shows the surface number distribution, FIG. 12(b) shows the total number distribution, and FIG. 12(c) shows the total mass distribution. The results shown in FIG. 12 show the first grain size distribution f after integration. 12 The difference from the result shown in FIG. 8 of Example 1-1 is that the linear sum was calculated using (x).

[0055] Fig. 13 shows the results of calculating the overall mass distribution of the mixed-grain-size deposit in Example 1-2. Fig. 13(a) shows the results of calculation for mixed-grain-size deposit No. 1, and Fig. 13(b) shows the results of calculation for mixed-grain-size deposit No. 2, which is the same as in Example 1-1. The graph shown with "Sieve" in Fig. 13 shows data measured using a sieve (mass ratio reflecting the actual state of the blended particles), and the graph shown with "3D" shows data calculated in Example 1-2 using 3D camera 1. As shown in Figure 13, compared with the result of Figure 2 calculated by the method described in Patent Document 2, the total mass distribution of the mixed-grain deposit calculated in Example 1-2 is close to the result measured using a sieve, and as in Example 1-1, the total mass distribution can be accurately calculated by distinguishing between particle types.

[0056] <Second embodiment> The second embodiment corresponds to the second method according to the present invention. That is, the method according to the second embodiment is a method that does not use the coefficient of the linear sum of the first particle size distribution approximating the second particle size distribution used in the method described in Patent Document 2 when calculating the coefficient of the linear sum of the first circularity distribution approximating the second circularity distribution.

[0057] FIG. 14 is a flow diagram illustrating steps of the particle size distribution measuring method according to the second embodiment. As shown in Fig. 14, the particle size distribution measuring method according to the second embodiment includes steps ST1' to ST6'. Each step will be described below in order, but the description of the parts common to the particle size distribution measuring method according to the first embodiment will be omitted as appropriate, and the differences will be mainly described. Note that in the second embodiment, an example will be described in which a particle size distribution (total mass distribution) of a mixed particle size laminate in which particles belonging to one particle size division are blended as sintered ore, which is a first type of particles, and particles belonging to one particle size division are blended as pellets, which is a second type of particles, is measured.

[0058] <Process ST1'> In step ST1' (corresponding to the first circularity distribution calculation step of the second method according to the present invention), single-particle-size samples (single-particle-size samples of one particle-size division), which are samples consisting only of particles having particle sizes that are in the same particle-size division, are prepared for both sintered ore and pellets. Specifically, in the second embodiment, when pellets belonging to particle size division 1 (10 mm<particle size≦15 mm) and sintered ore belonging to particle size division 2 (10 mm<particle size≦15 mm) are blended in any mass ratio in the mixed particle size deposit, a single particle size sample of pellets in particle size division 1 and a single particle size sample of sintered ore in particle size division 2 are prepared. Also, when pellets belonging to particle size division 1 (10 mm<particle size≦15 mm) and sintered ore belonging to particle size division 3 (15 mm<particle size≦25 mm) are blended in any mass ratio in the mixed particle size deposit, a single particle size sample of pellets in particle size division 1 and a single particle size sample of sintered ore in particle size division 3 are prepared. Then, similarly to step ST2 of the first embodiment, a first circularity distribution g indicating the relationship between the circularity (x′) and the number of surface layer particles of the single-particle-size sample is calculated based on the distance image of each single-particle-size sample acquired using the 3D camera 1. i (x') is calculated for each grain size division i.

[0059] <Process ST2'> In step ST2' (corresponding to the second circularity distribution calculation step of the second method according to the present invention), similar to step ST4 of the first embodiment, a second circularity distribution G(x') showing the relationship between the circularity (x') and number of surface particles of the mixed-grain-size deposit body is calculated based on a distance image of the mixed-grain-size deposit body acquired using a 3D camera 1.

[0060] <Process ST3'> In step ST3' (corresponding to the coefficient calculation step of the second method according to the present invention), the second circularity distribution G(x') of the mixed grain size sediment body is calculated by dividing the first circularity distribution g(x') by the grain size division i. i Linear sum of (x')Σb i ·g i (x') and the coefficient of the linear sum b iAt this time, unlike step ST6 of the first embodiment, in step ST3′ of the second embodiment, a first particle size distribution f approximating the second particle size distribution F(x) is calculated. i Linear sum of (x)Σa i f i Coefficient a of (x) i Without using the second circularity distribution G(x') and the first circularity distribution g i By directly using known approximation methods such as the least squares method for (x'), the coefficient b i Calculate.

[0061] <Process ST4', Process ST5', Process ST6'> Step ST4', step ST5' (corresponding to the overall number distribution calculation step of the second method according to the present invention), and step ST6' (corresponding to the overall mass distribution calculation step of the second method according to the present invention) are similar to steps ST7, ST8, and ST9 of the first embodiment, respectively. That is, in step ST4', the coefficient b i are regarded as the surface number ratios, which are the number ratios of surface particles belonging to grain size class i of each single-grain sample in the mixed-grain sediment, and the surface number distribution, which shows the relationship between grain size class i and the surface number ratios for each grain size class i, is calculated for the mixed-grain sediment. In addition, in step ST5', the surface number distribution calculated in step ST4' and the surface probability model are used to calculate the total number distribution, which is the relationship between the grain size division i and the total number ratio of particles for each grain size division i of the mixed grain size deposit body. Furthermore, in step ST6', the total number distribution calculated in step ST5' and the mass ratio w i Based on this, the total mass distribution, which is the relationship between the grain size division i and the mass ratio of the whole particles for each grain size division i of the mixed grain size deposit, is calculated.

[0062] According to the particle size distribution measuring method according to the second embodiment described above, in step ST3', the second circularity distribution G(x') of the mixed particle size sediment body calculated in step ST2' is calculated based on the first circularity distribution g(x') of each single particle size sample calculated in step ST1'. i Linear sum of (x')Σb i ·gi (x') and the coefficient of the linear sum b i Next, in step ST4′, the coefficient b i is regarded as a surface number ratio, which is the number ratio of surface layer particles belonging to the grain size division of each single grain size sample in the mixed grain size deposit, and a surface number distribution, which indicates the relationship between grain size division i and the surface number ratio for each grain size division i, is calculated. Thereafter, using a surface probability model in the same manner as in the method described in Patent Document 2, in step ST5', a total number distribution, which is the relationship between grain size division i and the number ratio of all particles for each grain size division i of the mixed grain size deposit, is calculated using the calculated surface number distribution and the surface probability model, and in step ST6', a total mass distribution, which is the relationship between grain size division i and the mass ratio of all particles for each grain size division i of the mixed grain size deposit, is calculated. Thus, the coefficient b of the linear sum i is considered to be the number ratio of each grain size class i of the surface layer particles of the mixed-grain sediment when the mixed-grain sediment is considered to be composed of a combination of each single grain size sample, and this coefficient b i Since the total mass distribution is finally calculated using the above, the total mass distribution can be calculated with high accuracy by distinguishing between particle types (pellets and sintered ore).

[0063] <Example 2> Hereinafter, as Example 2 (Example 2-1 and Example 2-2), an example of the results of calculating the total mass distribution by the particle size distribution measuring method according to the second embodiment will be described, focusing mainly on the differences from Example 1.

[0064] [Example 2-1] In step ST1' of Example 2-1, one tray T's worth (approximately 7 kg) of single-particle-size samples consisting of pellets of the aforementioned particle size category 1 and one tray T's worth of single-particle-size samples consisting of sintered ore of the aforementioned particle size category 2 were prepared, and the stacking state of each single-particle-size sample in tray T was changed, and the calculation of the circularity (x') of the surface particles of each single-particle-size sample based on the distance image of the surface particles was repeated 10 times, and the number of surface particles for each circularity range at intervals of 0.02 was tallied to calculate the first circularity distribution of each single-particle-size sample.

[0065] Next, in step ST2' of Example 2-1, pellets of particle size class 1 and sintered ore of particle size class 2 were mixed in a mass ratio of 25% and 75% respectively, and piled up to half the height (30 mm) of tray T to obtain a mixed particle size deposit. Then, in the same manner as in the case of single-grain samples, the deposition state of each mixed-grain-size sediment body in tray T was changed using 3D camera 1, and the calculation of the circularity (x') of the surface particles of the mixed-grain-size sediment body based on the distance image of the surface particles was repeated 10 times, and the number of surface particles for each circularity range at 0.02 intervals was tallied to calculate a second circularity distribution of the mixed-grain-size sediment body. FIG. 15 shows the linear sum of the second circularity distribution and the first circularity distribution of the mixed grain size deposit body calculated in Example 2-1. G(x') shown by a solid line in FIG. 15 is the second circularity distribution of the mixed-grain-size deposit body calculated in step ST2' of Example 2-1.

[0066] Next, in step ST3' of Example 2-1, the second circularity distribution G(x') of the mixed grain size sediment is calculated by the least squares method, and the first circularity distribution g(x') of each single grain size sample is calculated by the least squares method. i Linear sum of (x')Σb i ·g i (x') and the coefficient of the linear sum b i was calculated. The dashed line in Figure 15 shows Σb i ·g i (x') is the coefficient b calculated in step ST3' of Example 2-1 i It is a linear sum using

[0067] Next, in step ST4' of Example 2-1, each coefficient b i The surface number distribution was calculated by regarding these as the surface number ratios, which are the number ratios of surface particles belonging to grain size classes 1 and 2 in the mixed-grain sediment body. Figure 16 shows the surface number distribution, total number distribution, and total mass distribution of the mixed-grain deposit calculated in Example 2-1. Figure 16(a) shows the surface number distribution, Figure 16(b) shows the total number distribution, and Figure 16(c) shows the total mass distribution. The surface number ratio on the vertical axis of the surface number distribution shown in FIG. 16(a), calculated in step ST4' of Example 2-1, is calculated by multiplying each coefficient b i is expressed as a percentage.

[0068] Next, in step ST5' of Example 2-1, the total number distribution shown in FIG. 16(b) was calculated using the surface number distribution shown in FIG. 16(a) and the surface probability model. The total number ratio on the vertical axis of the total number distribution shown in FIG. 16(b) is the total number ratio of the whole particles that make up the mixed grain size deposit, and is a value expressed as a percentage so that the sum of the total number ratios corresponding to each grain size class is 100%. Note that when calculating the total number distribution, the mass ratio w i The values ​​of each parameter for the grain size classifications i = 1 and 2 except for 1 were used, and the height (bulk height) of the mixed grain size deposit was set to H = 30 mm.

[0069] Finally, in step ST6' of Example 2-1, the total number distribution shown in FIG. 16(b) and the mass ratio w i Based on (i=1, 2), the total mass distribution shown in Fig. 16(c) was calculated. The total mass ratio on the vertical axis of the total mass distribution shown in Fig. 16(c) is the mass ratio of all the particles that make up the mixed-grain sediment, and is expressed as a percentage so that the sum of the total mass ratios corresponding to each grain size class is 100%.

[0070] Fig. 17 shows the results of calculating the total mass distribution of the mixed particle size deposit in Example 2-1. In Fig. 17, the graph indicated by "sieve" shows data measured using a sieve (mass ratio reflecting the actual state of the mixed particles), and the graph indicated by "3D" shows data calculated in Example 2-1 using 3D camera 1. As shown in Figure 17, the total mass distribution of the mixed-grain sediment calculated in Example 2-1 is close to the result measured using a sieve, and the total mass distribution can be calculated with high accuracy by distinguishing between particle types.

[0071] [Example 2-2] Example 2-2 differs from Example 2-1 in that, in step ST1', a single particle size sample consisting of pellets of the above-mentioned particle size category 1, which is equivalent to one tray T (approximately 7 kg), and a single particle size sample consisting of sintered ore of the above-mentioned particle size category 3, which is equivalent to one tray T, are prepared, and the first circularity distribution of each single particle size sample is calculated. Also, Example 2-2 differs from Example 2-1 in that, in step ST2', pellets of particle size category 1 and sintered ore of particle size category 3 are mixed in a mass ratio of 25% and 75% and piled up to 2 / 3 of the height (40 mm) in the tray T to obtain a mixed particle size deposit, and the second circularity distribution of the mixed particle size deposit is calculated. Also, in Example 2-2, when calculating the total number distribution in step ST5', the mass ratio w i In addition to using the values ​​of the parameters for the particle size divisions i=1 and 3 except for 1, 2, the height (bulk height) of the mixed particle size deposit H was set to 40 mm. Furthermore, in Example 2-2, when calculating the total mass distribution in step ST6', the mass ratio w i This example differs from Example 2-1 in that (i=1, 3) was used. Other points are the same as Example 2-1, so further explanation will be omitted and only the results will be described below.

[0072] FIG. 18 shows the linear sum of the second circularity distribution and the first circularity distribution of the mixed grain size deposit body calculated in Example 2-2. G(x') shown by a solid line in FIG. 18 is the second circularity distribution of the mixed-grain-size deposit body calculated in step ST2' of Example 2-2. The dashed line in Figure 18 shows Σb i ·g i (x') is the coefficient b calculated in step ST3' of Example 2-2 i It is a linear sum using

[0073] Figure 19 shows the surface number distribution, total number distribution, and total mass distribution of the mixed-grain deposit calculated in Example 2-2. Figure 19(a) shows the surface number distribution, Figure 19(b) shows the total number distribution, and Figure 19(c) shows the total mass distribution. The surface number ratio on the vertical axis of the surface number distribution shown in Figure 19(a) is calculated by multiplying each coefficient bi The total number ratio on the vertical axis of the total number distribution shown in Figure 19(b) is the total number ratio of all particles that make up the mixed-grain deposit, and is expressed as a percentage so that the sum of the total number ratios corresponding to each grain size class is 100%. The total mass ratio on the vertical axis of the total mass distribution shown in Figure 19(c) is the total mass ratio of all particles that make up the mixed-grain deposit, and is expressed as a percentage so that the sum of the total mass ratios corresponding to each grain size class is 100%.

[0074] Fig. 20 shows the results of calculating the total mass distribution of the mixed particle size deposit in Example 2-2. In Fig. 20, the graph indicated by "sieve" is the data measured using a sieve (mass ratio reflecting the actual state of the mixed particles), and the graph indicated by "3D" is the data calculated in Example 2-2 using 3D camera 1. As shown in Figure 20, the total mass distribution of the mixed-grain sediment calculated in Example 2-2 is close to the result measured using a sieve, and the total mass distribution can be calculated with high accuracy by distinguishing between particle types. In the case of Example 2-2, since particle size category 1 (10 mm<particle size≦15 mm) of the pellets mixed in the mixed particle size deposit and particle size category 3 (15 mm<particle size≦25 mm) of the sintered ore are not the same particle size category (there are no particles in the sintered ore that belong to the same particle size category as the pellets), it is considered that even if the method described in Patent Document 2 is used, it is possible to accurately calculate the overall mass distribution by distinguishing between particle types.

[0075] In Examples 1 and 2, the particle size distribution of a mixed-grain-size deposit piled up in a tray T is measured, but the present invention can also measure the particle size distribution of a mixed-grain-size deposit piled up and transported on a belt conveyor. However, in the case of a mixed-grain-size deposit piled up and transported on a belt conveyor, unlike a mixed-grain-size deposit piled up in a tray T, the height H of the mixed-grain-size deposit used in the surface probability model is likely to fluctuate during transport, so it is preferable to actually measure the height H. As a method for measuring (calculating) the height H of the mixed-grain deposit, the method described in Patent Document 2, in which the cross section of the mixed-grain deposit deposited on a belt conveyor is approximated as a trapezoid, can be applied, so a detailed explanation of this method will be omitted here.

[0076] In addition, in the particle size distribution measurement method of the first embodiment, in step ST1, a first particle size distribution showing the relationship between the particle size and area of ​​surface particles of a single-particle-size sample is calculated, and in step ST3, a second particle size distribution showing the relationship between the particle size and area of ​​surface particles of a mixed sediment body is calculated. However, instead of these, it is also possible to calculate a second particle size distribution showing the relationship between the particle size and number of surface particles of a mixed sediment body together with the first particle size distribution showing the relationship between the particle size and volume of surface particles of a single-particle-size sample, or to calculate a second particle size distribution showing the relationship between the particle size and volume of surface particles of a mixed sediment body together with the first particle size distribution showing the relationship between the particle size and volume of surface particles of a single-particle-size sample. Although we will not go into the details of the results, even if the first particle size distribution and the second particle size distribution are replaced with those that show the relationship described above, it is possible to accurately calculate the overall mass distribution of the mixed-grain sediment body by distinguishing between particle types. [Explanation of symbols]

[0077] 1. 3D camera (means for acquiring distance images) ST1... process (first particle size distribution calculation step) ST2... process (first circularity distribution calculation step) ST3... process (second particle size distribution calculation step) ST4... process (second circularity distribution calculation step) ST5... process (first coefficient calculation step) ST6... process (second coefficient calculation step) ST7...Process ST8... process (total number distribution calculation step) ST9... process (total mass distribution calculation step) T···Tray

Claims

1. a first particle size distribution calculation step of preparing single-particle-size samples, which are samples consisting of only particles having the same particle size, which is a particle size division determined by the particle size, for a plurality of particle size divisions for a first type of particles, and preparing a single particle size division for a second type of particles different from the first type, and imaging the surface layer of each of the single-particle-size samples while changing the deposition state of the single-particle-size samples to obtain distance images showing the distance from a reference position to the particles in the surface layer, and calculating a first particle size distribution showing the relationship between the particle size and area of ​​the particles in the surface layer of the single-particle-size sample for each of the plurality of particle size divisions for the first type of particles, and for the one particle size division for the second type of particles, based on the distance images of the single-particle-size samples; a first circularity distribution calculation step of calculating a first circularity distribution indicating a relationship between the circularity and the number of particles in the surface layer of the single-particle-size sample for each of the plurality of particle size divisions for the first type of particles, and for the one particle size division for the second type of particles, based on the distance image of the single-particle-size sample; a second particle size distribution calculation step of imaging a surface layer of a mixed-grain-size deposit body in which the first type of particles belonging to the plurality of particle size divisions and the second type of particles belonging to the one particle size division are blended, while changing the deposition state of the mixed-grain-size deposit body, acquiring a distance image showing the distance from a reference position to the particles of the surface layer, and calculating a second particle size distribution showing the relationship between the particle size and area of ​​the particles of the surface layer of the mixed-grain-size deposit body based on the distance image of the mixed-grain-size deposit body; a second circularity distribution calculation step of calculating a second circularity distribution indicating a relationship between the circularity and the number of particles in the surface layer of the mixed grain size deposit body based on the distance image of the mixed grain size deposit body; a first coefficient calculation step of approximating the second particle size distribution by a linear sum of the first particle size distributions for the plurality of particle size ranges calculated for the first type of particles and the first particle size distribution for the one particle size range calculated for the second type of particles, and calculating a first coefficient which is a coefficient of the linear sum; a second coefficient calculation step of approximating the second circularity distribution by a linear sum of the first circularity distribution for each of the plurality of particle size ranges calculated for the first type of particles and the first circularity distribution for the one particle size range calculated for the second type of particles, and calculating a second coefficient that is a coefficient of the linear sum; a total number distribution calculation step of calculating, from the second coefficient, a total number distribution which is a relationship between the plurality of particle size classes of the first type of particles and the one particle size class of the second type of particles, and the total number ratio of the plurality of particle size classes of the first type of particles and the one particle size class of the second type of particles in the mixed particle size deposit body, using a surface probability model which estimates the number distribution of the entire deposited particles from the number distribution of particles in a surface layer; an overall mass distribution calculation step of calculating an overall mass distribution, which is a relationship between a mass ratio of the entire particles for each of the plurality of particle size divisions of the first type of particles and the one particle size division of the second type of particles, based on the overall number distribution and a mass ratio for the plurality of particle size divisions of the first type of particles and the one particle size division of the second type of particles; having In the first coefficient calculation step, only the first coefficient for a particle size division of the first type of particles that is different from the one particle size division of the second type of particles is determined; In the second coefficient calculation step, the second coefficient is calculated under a condition that the second coefficient for a particle size division, which is different from the one particle size division of the second type of particles, among the plurality of particle size divisions of the first type of particles is proportional to the first coefficient determined in the first coefficient calculation step. Particle size distribution measurement method.

2. In the first particle size distribution calculation step, instead of a first particle size distribution showing a relationship between the particle size and the area of ​​the particles in the surface layer of the single particle size sample, a first particle size distribution showing a relationship between the particle size and the number of particles in the surface layer of the single particle size sample is calculated; 2. The particle size distribution measuring method according to claim 1, wherein in the second particle size distribution calculation step, a second particle size distribution indicating the relationship between the particle size and the number of particles in the surface layer of the mixed deposit is calculated instead of a second particle size distribution indicating the relationship between the particle size and the area of ​​the particles in the surface layer of the mixed deposit.

3. In the first particle size distribution calculation step, instead of a first particle size distribution showing a relationship between the particle size and the area of ​​the surface layer particles of the single particle size sample, a first particle size distribution showing a relationship between the particle size and the volume of the surface layer particles of the single particle size sample is calculated; 2. The particle size distribution measuring method according to claim 1, wherein in the second particle size distribution calculation step, a second particle size distribution indicating the relationship between the particle size and the volume of the particles in the surface layer of the mixed deposit is calculated instead of a second particle size distribution indicating the relationship between the particle size and the area of ​​the particles in the surface layer of the mixed deposit.

4. a first circularity distribution calculation step of preparing single-particle-size samples, which are samples consisting of only particles having the same particle size classification, which is a classification determined by particle size, for each of a first type of particles and a second type of particles different from the first type of particles, imaging the surface layer of each of the single-particle-size samples while changing the deposition state of the single-particle-size samples, obtaining distance images showing the distance from a reference position to the particles in the surface layer, and calculating a first circularity distribution showing the relationship between the circularity and the number of particles in the surface layer of the single-particle-size sample for each of the particle size classifications of the first type of particles and the second type of particles based on the distance images of the single-particle-size samples; a second circularity distribution calculation step of imaging a surface layer of a mixed-grain-size deposit body in which the first type of particles and the second type of particles belonging to the grain size divisions of the single grain size sample are blended while changing the deposition state of the mixed-grain-size deposit body, acquiring a distance image showing the distance from a reference position to the particles of the surface layer, and calculating a second circularity distribution showing the relationship between the circularity and the number of particles of the surface layer of the mixed-grain-size deposit body based on the distance image of the mixed-grain-size deposit body; a coefficient calculation step of approximating the second circularity distribution by a linear sum of the first circularity distributions calculated for each of the particle size ranges of the first type of particles and the second type of particles, and calculating a coefficient of the linear sum; a total number distribution calculation step of calculating, from the coefficients, a total number distribution which is a relationship between the particle size classes of the first type of particles and the second type of particles and the total particle number ratios of each particle size class of the first type of particles and the second type of particles in the mixed particle size deposit body, using a surface probability model which estimates the number distribution of the entire deposited particles from the number distribution of particles in the surface layer; an overall mass distribution calculation step of calculating an overall mass distribution, which is a relationship between the overall mass ratio of the first type of particles and the second type of particles for each particle size division and the total number distribution and a mass ratio of the first type of particles and the second type of particles for each particle size division, based on the overall number distribution and the mass ratio of the first type of particles and the second type of particles for each particle size division; The particle size distribution measuring method according to claim 1,

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