Selection method for iron ore

Abstract

To provide a selection method enabling efficient separation and selection of iron ore into iron ore having a large amount of gangue component and iron ore having a small amount of the gangue component, and enabling sorting of the iron ore having a small amount of the gangue component to a sintering step.SOLUTION: A selection method for iron ore has: a threshold value determination step ST1 determining a threshold value for intensity value of a component B by using an image for determining threshold value which is captured by imaging iron ore for determining threshold value; and a selection step ST2 classifying and selecting the subject iron ore for selection into a subject iron ore for selection of a first section corresponding to a pixel region where the intensity value of component B is the threshold value or more in the subject image for selection and a subject iron ore for selection of a second section corresponding to a pixel region where the intensity value of component B is less than a threshold value in the subject image for selection, by using a subject image for selection which is captured by imaging a subject iron ore for selection and the threshold value. In the selection step, the subject iron ore for selection in selected second section is sorted to a sinter step. Further, in the selection step, the subject iron ore for selection in the selected first section is sorted to an iron ore pulverization step ST3.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a method for sorting iron ore, and more particularly to a method for efficiently separating and sorting iron ore into iron ore with a high gangue content and iron ore with a low gangue content, and for allocating the iron ore with a low gangue content to a sintering process. [Background technology]

[0002] In recent years, due to the depletion of high-quality iron ore, the iron content of iron ore used as a raw material for steelmaking has decreased, while the gangue components SiO2 and Al2O3 have tended to increase. An increase in the gangue content of iron ore inhibits melting and assimilation in the sintering process, causing a decrease in product yield and ultimately sintering productivity. Furthermore, when sintered ore is produced using iron ore with a high gangue content as a raw material and used in a blast furnace, this leads to an increase in the amount of slag generated, which in turn leads to an increase in the blast furnace production costs due to a worsening of the reducing agent ratio and an increase in CO2 emissions. For this reason, it is desirable to efficiently separate and sort iron ore into iron ore with a high gangue content and iron ore that is mainly composed of iron oxide and has a low gangue content, and to allocate the iron ore with a low gangue content to the sintering process.

[0003] For example, Patent Document 1 proposes a method for analyzing the abundance ratio of useful minerals by performing image analysis on ore containing useful minerals (opaque minerals), useless minerals (transparent minerals), and gangue minerals. Furthermore, Patent Document 2 proposes a method for determining whether dust is dust resulting from iron production or silica sand by performing image analysis of the dust. However, Patent Documents 1 and 2 do not propose any method for efficiently separating and sorting iron ore into iron ore with a high gangue content and iron ore with a low gangue content. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-79253 [Patent Document 2] Japanese Patent Application Laid-Open No. 2011-203128 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above-mentioned problems of the conventional art, and an object of the present invention is to provide a sorting method that can efficiently separate and sort iron ore into iron ore with a high gangue content and iron ore with a low gangue content, and can assign the iron ore with a low gangue content to a sintering process. [Means for solving the problem]

[0006] To solve the above-mentioned problems, the present inventors conducted extensive research and found that iron ore with a high gangue content exhibits a whitish appearance color, while iron ore that is mainly composed of iron oxide and has a low gangue content exhibits an appearance color other than whitish, such as black, gray, red, or yellow (hereinafter, these will be referred to as "other colors") [1]. Furthermore, the inventors found that, among the RGB components of a color image of iron ore, the intensity value of the B component is high for whitish iron ore with a high gangue content and low gangue content, and is low for other-color iron ore with a low gangue content, with a large difference between the two. Therefore, the inventors conceived that by extracting the intensity value of the B component from a color image of iron ore, iron ore with a high gangue content and iron ore with a low gangue content can be automatically and efficiently classified and sorted into iron ore with a high gangue content and iron ore with a low gangue content according to the intensity value. The present invention was completed based on the above findings of the inventors.

[0007] That is, in order to solve the above-mentioned problems, the present invention has a threshold determination step of determining a threshold value for the intensity value of the B component among the RGB components of a color image using a threshold determination image, which is a color image of a threshold determination iron ore that is the same type of iron ore as the target iron ore to be sorted, and a sorting step of classifying and sorting the target iron ore into two categories using a sorting target image, which is a color image of the target iron ore, and the threshold value. The threshold determination step includes an image acquisition step of acquiring the threshold determination image by imaging the target iron ore, an extraction step of extracting the intensity value of the B component among the RGB components of the threshold determination image, and a peak of the distribution of intensity values ​​of the B component in a pixel region corresponding to the target iron ore in the threshold determination image. and a determination step of determining, as the threshold value, an intensity value that is larger than the intensity value by a predetermined value, wherein the sorting process includes an image acquisition step of imaging the iron ore to be sorted to obtain the image to be sorted; an extraction step of extracting the intensity value of the B component from the RGB components of the image to be sorted; a sorting step of classifying and sorting the iron ore to be sorted into two categories: a first category of iron ore to be sorted that corresponds to pixel regions in the image to be sorted where the intensity value of the B component is equal to or greater than the threshold value, and a second category of iron ore to be sorted that corresponds to pixel regions in the image to be sorted where the intensity value of the B component is less than the threshold value; and a sorting step of sorting the second category of iron ore to be sorted in the sorting step to a sintering process.

[0008] In the present invention, "iron ore for determining a threshold value, which is the same type of iron ore as the iron ore to be sorted" means iron ore mined from the same mine as the iron ore to be sorted and has equivalent mineral properties, and includes iron ore mined or received at a different time from the iron ore to be sorted, as well as cases where a sample taken from the iron ore to be sorted is used as the iron ore for determining a threshold value. In addition, in the present invention, a "color image" means an image having the hue components R (red), G (green), and B (blue), which is obtained by photographing iron ore in an environment where the iron ore is irradiated with light emitted from a daylight, daylight, or white light source, or in an environment where the iron ore is irradiated with sunlight.

[0009] According to the present invention, the threshold determination process determines a threshold for the intensity value of the B component among the RGB components of the color image, and the sorting process classifies and sorts the iron ore to be sorted into two categories (first category and second category) using the sorting target image, which is a color image of the iron ore to be sorted, and assigns the iron ore to be sorted in the second category to the sintering process. Specifically, in the threshold determination process, an intensity value that is a predetermined value greater than the peak intensity value of the distribution of intensity values ​​of the B component in the pixel area corresponding to the iron ore for threshold determination in the threshold determination image, which is a color image of the iron ore for threshold determination, is determined as the threshold value. In the sorting process, the iron ore to be sorted corresponding to pixel regions in the sorting target image where the intensity value of the B component is equal to or greater than a threshold value is classified and sorted as the first-division iron ore to be sorted. According to the inventor's findings, the iron ore to be sorted in the first division is expected to be white iron ore with a high gangue content. In the sorting process, the iron ore to be sorted corresponding to pixel regions in the sorting target image where the intensity value of the B component is less than the threshold value is classified and sorted as the second-division iron ore to be sorted. According to the inventor's findings, the iron ore to be sorted in the second division is expected to be other-color iron ore with a low gangue content. Therefore, by sorting the sorted second-division iron ore to be sorted to the sintering process, it is possible to sort iron ore with a low gangue content to the sintering process.

[0010] As described above, according to the present invention, by using only the intensity values ​​of the B component of the threshold determination image obtained by capturing the iron ore for threshold determination and the target image obtained by capturing the iron ore to be sorted, the target iron ore can be automatically and efficiently classified and sorted into a first category of target iron ore that is expected to be white with a high gangue content and a second category of target iron ore that is expected to be other-colored with a low gangue content. Therefore, by allocating the selected second category of target iron ore to the sintering process, it is possible to reduce the deterioration of sintering productivity in the sintering process, the increase in production costs in the blast furnace, and the increase in CO2 emissions.

[0011] According to the findings of the present inventors, even if the iron ore is white and contains a large amount of gangue, if it is finely crushed to a particle size of about 1 mm or less, the melting and assimilation properties in the sintering process are improved compared to before crushing, and deterioration of sintering productivity can be reduced. Therefore, preferably, the present invention further includes an iron ore crushing process, and in the sorting step of the sorting process, the first category of iron ore to be sorted selected in the sorting step is sorted to the iron ore crushing process, and in the iron ore crushing process, the first category of iron ore to be sorted is crushed, and the entire amount of the crushed first category of iron ore to be sorted is subjected to the sintering process.

[0012] According to the above-mentioned preferred method, the first-class target iron ore, which is expected to be white iron ore containing a large amount of gangue components, is crushed in the iron ore crushing step, and the crushed first-class target iron ore is subjected to the sintering step in its entirety. As described above, the melting and assimilation properties of the crushed first-class target iron ore are improved compared to before crushing, and deterioration in sintering productivity can be reduced. This has the advantage of allowing the first-class target iron ore to be effectively utilized.

[0013] In the above-described preferred method, it is more preferable that the entire amount of the pulverized first fraction of the iron ore to be separated is subjected to a pelletizing process using a pan pelletizer in the sintering step.

[0014] According to the above-mentioned more preferable method, the melting and assimilation properties of the first fraction of the iron ore to be sorted after pulverization are further improved, and the deterioration of sintering productivity can be further reduced.

[0015] In addition, the present invention preferably further includes an iron ore crushing process and an ore-dressing process, and in the sorting step of the sorting process, the first category of iron ore to be sorted out in the sorting step is sorted to the iron ore crushing process, and in the iron ore crushing process, the first category of iron ore to be sorted out is crushed, and in the ore-dressing process, the crushed first category of iron ore to be sorted out is separated and sorted into particles mainly composed of iron-bearing minerals and particles mainly composed of gangue using an ore-dressing process, and the separated and sorted particles mainly composed of iron-bearing minerals are subjected to the sintering process, and the separated and sorted particles mainly composed of gangue are disposed of as waste.

[0016] According to the above-described preferred method, the iron ore to be sorted in the first division, which is expected to be white iron ore containing a large amount of gangue, is crushed in the iron ore crushing step, and then, in the ore dressing step, the crushed first division of the iron ore to be sorted is separated and sorted into particles mainly composed of iron-bearing minerals and particles mainly composed of gangue using an ore dressing method. The particles mainly composed of iron-bearing minerals are then subjected to a sintering step, and the particles mainly composed of gangue are discarded. This allows the particles mainly composed of iron-bearing minerals from the first division of the iron ore to be sorted to be effectively utilized, and by discarding the particles mainly composed of gangue, which inhibit melting and assimilation in the sintering step, it is possible to reduce deterioration in sintering productivity. [Effects of the Invention]

[0017] According to the present invention, it is possible to efficiently separate and sort iron ore into iron ore with a large amount of gangue components and iron ore with a small amount of gangue components, and to assign the iron ore with a small amount of gangue components to the sintering process. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a diagram schematically illustrating a general configuration of a sorting device for carrying out a sorting method according to an embodiment of the present invention. [Figure 2]FIG. 1 is a flowchart showing a schematic procedure of a sorting method according to a first embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing an example of a color image obtained by capturing an image of a sample extracted from the iron ore to be sorted according to an embodiment of the present invention. [Figure 4] FIG. 6 is a flowchart showing the outline of the procedure of a sorting method according to a second embodiment of the present invention. [Figure 5] FIG. 10 is a diagram showing the results of point analysis in an example of the present invention. [Figure 6] 1 is a diagram illustrating the contents of an embodiment of the present invention. [Figure 7] FIG. 10 is a diagram showing the distribution of intensity values ​​of the B component in a pixel region corresponding to the iron ore for threshold determination in the threshold determination image, obtained in an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, methods for sorting iron ore according to embodiments (first and second embodiments) of the present invention will be described.

[0020] <<First Embodiment>> Fig. 1 is a diagram showing a schematic configuration of a sorting device for carrying out a sorting method according to embodiments (first and second embodiments) of the present invention, and Fig. 2 is a flow chart showing a schematic procedure of the sorting method according to the first embodiment.

[0021] <Sorting device> First, the sorting device will be described. As shown in FIG. 1, a sorting device 100 of this embodiment, which is common to the first and second embodiments, includes a conveyor 10, an imaging means 20, a calculation control means 30, and an air gun 40. The conveyor 10 is a means for transporting the iron ore to be sorted. FIG. 3 is a diagram showing an example of a color image of a sample taken from the iron ore to be sorted in this embodiment (although FIG. 3 shows a monochrome image, it is actually a color image). FIG. 3(a) is a color image of a mixture of white iron ore O1 to be sorted and other colored (black, gray, red, yellow, etc.) iron ore O2 to be sorted, and FIG. 3(b) is a color image of the white iron ore O1 to be sorted. Note that the iron ore for threshold determination described below is the same type of iron ore as the iron ore to be sorted, and therefore has a white or other colored appearance color, similar to the iron ore to be sorted shown in FIG. 3. In this specification, the iron ore for threshold determination will also be referred to by the same symbols O1 and O2 as the iron ore to be sorted, depending on its appearance color.

[0022] As shown in FIG. 1, the sorting apparatus 100 of this embodiment includes three conveyors 10a, 10b, and 10c as the conveyor 10. A mixture of white iron ore O1 and other-colored iron ore O2 is placed and transported on the conveyor 10a, which is located at the most upstream side in the transport direction of the iron ore to be sorted (the direction of the thick arrow in FIG. 1). At the end (the downstream end in the transport direction) of the conveyor 10a, the iron ores O1 and O2 to be sorted fall naturally toward the conveyor 10b, which is located below the conveyor 10a. Along this falling path, an imaging unit 20 captures images of the iron ores O1 and O2 to be sorted and acquires sorting target images. The acquired sorting target images are input to the arithmetic and control unit 30, which executes arithmetic and control processes, such as image processing, described below, to classify the iron ores O1 and O2 into two categories of sorting target iron ore, i.e., first and second categories. Next, the arithmetic and control means 30 sends a control signal to the air gun 40 to drive and control the air gun 40 at the moment when one of the iron ores to be sorted (in the example shown in FIG. 1 , this is the first-category iron ore to be sorted, which is expected to be white iron ore O1) passes in front of the air gun 40. This causes the air gun 40 to emit compressed air Air forward, and the iron ore to be sorted in one of the categories is blown toward the conveyor 10c, which is located below the conveyor 10b, and is transported by the conveyor 10c. Ignoring air resistance acting on the iron ore to be sorted, the arithmetic and control means 30 can calculate the timing at which the iron ore to be sorted in one of the categories passes in front of the air gun 40 from the distance between the imaging means 20 and the air gun 40 and the acceleration of gravity. On the other hand, the other sorted iron ore (in the example shown in FIG. 1, the second sorted iron ore, which is expected to be iron ore O2 of a different color) is transported by conveyor 10b. In this way, one sorted iron ore is sorted onto conveyor 10c, and the other sorted iron ore is sorted onto conveyor 10b.

[0023] The imaging means 20 can be configured in various ways, such as a CCD camera or a CMOS camera, as long as it can capture images of the iron ores O1 and O2 to be sorted and obtain an image of the sorted object, which is a color image having each of the RGB components as its hue.

[0024] The arithmetic control means 30 is configured, for example, by a computer equipped with a hardware processor such as a CPU and memories such as RAM, ROM, and a hard disk. The memory of the arithmetic control means 30 stores a threshold value Th, which will be described later. The memory of the arithmetic control means 30 also stores an image analysis program, which is executed by the hardware processor to perform the arithmetic processing, which will be described later. As the image analysis program, for example, general image analysis software capable of separating and extracting the intensity values ​​of each RGB component, such as "WinROOF" or "Image J" manufactured by Mitani Shoji Co., Ltd., can be used. In this arithmetic processing, the threshold value Th stored in the memory is used to classify the iron ores O1 and O2 to be sorted into two categories, the first and second categories of iron ores to be sorted.

[0025] <Selection method> Next, the selection method will be described. 2, the sorting method according to the first embodiment includes a threshold value determining step ST1 and a sorting step ST2. In addition, as a preferred embodiment, the sorting method according to the first embodiment further includes an iron ore crushing step ST3. Each of the steps ST1 to ST3 will be described below.

[0026] [Threshold determination process ST1] The threshold determination step ST1 is a step of preparing a threshold determination iron ore, which is the same type of iron ore as the iron ore to be sorted, and determining a threshold Th for the intensity value of the B component among the RGB components of the color image using a threshold determination image, which is a color image of the threshold determination iron ore. As the threshold determination iron ore, for example, a sample of about tens to hundreds of grams extracted from the iron ore to be sorted is used. The threshold determination process ST1 in the first embodiment can be performed in either the first determination mode or the second determination mode, but regardless of the determination mode, the threshold determination process ST1 includes a cleaning and drying step ST11, an image acquisition step ST12, an extraction step ST13, and a determination step ST14.

[0027] (Washing and drying step ST11) In the washing and drying step ST11, the threshold determination iron ore is washed and then dried so that it can be properly imaged in the subsequent image acquisition step ST12. A tabletop ultrasonic cleaner, for example, can be used to wash the threshold determination iron ore. The threshold determination iron ore is placed in a beaker or a tray, which is then placed in the ultrasonic cleaner. Water is added until the threshold determination iron ore is completely submerged, and the cleaner is vibrated for several minutes to remove fine particles adhering to the surface of the threshold determination iron ore. The threshold determination iron ore is then removed from the ultrasonic cleaner and placed in a dryer, such as an oven, where it is dried at a temperature of about 100°C for several hours. When washing and drying the iron ore for threshold determination in the sorting apparatus 100 as shown in FIG. 1 (when extracting the iron ore for threshold determination from the iron ore to be sorted after washing and drying), for example, high-pressure water may be sprayed onto the iron ore for threshold determination (iron ore to be sorted) while the iron ore for threshold determination (iron ore to be sorted) is being transported on the conveyor 10a to remove fine powder adhering to the surface, and then hot air (exhaust hot air) at about 100 to 200°C may be blown onto the iron ore for threshold determination (iron ore to be sorted) to dry it.

[0028] (Image acquisition step ST12) In the image acquisition step ST12, for example, an imaging means similar to the imaging means 20 shown in FIG. 1 is used to image the washed and dried iron ore for threshold determination to obtain a threshold determination image. The imaging by the imaging means is performed in an environment where the iron ore for threshold determination is irradiated with light emitted from a daylight, coulour or white light source (e.g., an LED light source), or in an environment where it is irradiated with sunlight. Furthermore, to minimize the occurrence of pixel regions with high intensity values ​​(noise regions) other than the iron ore for threshold determination in the threshold setting image, an anti-reflection sheet or the like that suppresses light reflection may be placed in the background, if necessary.

[0029] Specifically, in the first determination mode, in the image acquisition step ST12, the washed and dried threshold determination iron ore is visually classified into two categories of threshold determination iron ore: white threshold determination iron ore O1 and other color threshold determination iron ore O2, and threshold determination images are acquired for each of the two categories of threshold determination iron ore O1 and O2. Note that when the threshold determination iron ore is visually classified as in the first determination mode, it is difficult to determine the appearance color if the particle size is too small. Therefore, it is preferable to classify a sample taken from the iron ore to be sorted using a sieve and use iron ore with a particle size of 1 mm or more as the threshold determination iron ore. On the other hand, in the second determination mode, in the image acquisition step ST12, a threshold determination image is acquired for the threshold determination iron ore in a state in which white threshold determination iron ore O1 and other color threshold determination iron ore O2 are mixed.

[0030] (Extraction step ST13) In extraction step ST13, for example, a means having a calculation processing function similar to that of the calculation control means 30 shown in Fig. 1 (or a conversion of the calculation control means 30) is used to extract the intensity value of the B component from among the R, G, B components of the threshold determination image. If the threshold determination image is an 8-bit image, the intensity value of the B component, with the darkest value being 0 and the brightest value being 255, is extracted for each pixel constituting the threshold determination image.

[0031] Specifically, in the first determination mode, in the extraction step ST13, the intensity value of the B component is extracted for each of the threshold determination images for two categories of threshold determination iron ore (white-colored threshold determination iron ore O1 and other-colored threshold determination iron ore O2). On the other hand, in the second determination mode, in the extraction step ST13, the intensity value of the B component is extracted from the threshold determination image acquired in a state in which the two categories of threshold determination iron ore O1 and O2 are mixed.

[0032] (Decision step ST14) In the determination step ST14, for example, using a means having a calculation processing function similar to the calculation control means 30 shown in Figure 1 (or by repurposing the calculation control means 30), an intensity value that is a predetermined value greater than the peak intensity value of the distribution of intensity values ​​of the B component in the pixel region corresponding to the threshold determination iron ore in the threshold determination image is determined as the threshold value Th.

[0033] Specifically, in the first determination mode, in the determination step ST14, as shown in FIG. 7(a) described later, in a threshold determination image acquired for a white threshold determination iron ore O1, the distribution of intensity values ​​of the B component in a pixel region corresponding to the white threshold determination iron ore O1 is obtained, and its peak intensity value is calculated. In the example shown in FIG. 7(a), the peak intensity value is in the range of 35 or more and less than 59 (therefore, the peak intensity value is set to, for example, an intermediate value of 47). Also, as shown in FIG. 7(b) described later, in a threshold determination image acquired for a different color threshold determination iron ore O2, the distribution of intensity values ​​of the B component in a pixel region corresponding to the different color threshold determination iron ore O2 is obtained, and its peak intensity value is calculated. In the example shown in FIG. 7(b), the peak intensity value is in the range of 35 or more and less than 59 (therefore, the peak intensity value is set to, for example, an intermediate value of 47). Then, an intensity value that is a predetermined value greater than the average value of the peak intensity values ​​of each threshold determination image (in the example shown in FIG. 7, the peak intensity values ​​of each threshold determination image are the same, so the average value is also the same, for example, 47) is determined as the threshold value Th. This predetermined value can be determined so that, as shown in FIG. 7(b), there are no or almost no pixel regions corresponding to the threshold determination iron ore O2 of other colors where the intensity value of the B component is greater than or equal to the threshold value Th (= peak intensity value + predetermined value). In the example shown in FIG. 7, an intensity value of 108, which is approximately 60 greater than the peak intensity value, is determined as the threshold value Th.

[0034] On the other hand, in the second determination mode, in the determination step ST14, the intensity distribution of the B component in the pixel region corresponding to the threshold determination iron ores O1 and O2 is obtained in the threshold determination image acquired in a state where the threshold determination iron ores O1 and O2 are mixed, and the peak intensity value is calculated. Then, an intensity value that is larger than the peak intensity value of the threshold determination image by a predetermined value is determined as the threshold value Th. In the case where the threshold value determination iron ores O1 and O2 in the example shown in FIG. 7 are mixed, the threshold value Th determined in the second determination manner is the same as the threshold value Th determined in the first determination manner.

[0035] The threshold value Th determined in the threshold value determination step ST1 described above is stored in the memory of the arithmetic control means 30 of the sorting apparatus 100 and is used in the sorting step ST2. This threshold value may be a fixed value, but it is also possible to determine and store multiple threshold values ​​according to the mineral properties of the iron ore to be sorted, and to select and use the threshold value Th according to the mineral properties of the iron ore to be sorted. Furthermore, it is also possible to appropriately update and store the threshold value Th even for the same type of iron ore to be sorted.

[0036] [Sorting process ST2] The sorting process ST2 is a process in which the sorting device 100 classifies and sorts the iron ores O1 and O2 to be sorted into two categories (first and second categories) using a sorting target image, which is a color image of the iron ores O1 and O2 to be sorted, and a threshold value Th. The sorting step ST2 of the second embodiment includes a washing and drying step ST21, an image acquiring step ST22, an extracting step ST23, a sorting step ST24, and a sorting step ST25.

[0037] (Washing and drying step ST21) In the washing and drying step ST21, the iron ores O1 and O2 to be sorted are washed and then dried so that the iron ores O1 and O2 to be sorted can be properly imaged in the subsequent image acquisition step ST22. For example, while the iron ores O1 and O2 to be sorted are being transported on the conveyor 10a, high-pressure water may be sprayed from a high-pressure washer (not shown) onto the iron ores O1 and O2 to be sorted to remove fine powder adhering to the surface, and then hot air (exhaust hot air) at about 100 to 200°C may be blown from a dryer (not shown) onto the iron ores O1 and O2 to be sorted to dry them.

[0038] (Image acquisition step ST22) In the image acquisition step ST22, the washed and dried iron ores O1 and O2 to be sorted are imaged using the imaging means 20 to obtain an image of the iron ores to be sorted. The imaging by the imaging means 20 is performed in an environment where the iron ores O1 and O2 to be sorted are irradiated with light emitted from a daylight, daylight, or white light source (e.g., an LED light source), or in an environment where they are irradiated with sunlight. Furthermore, to minimize the occurrence of pixel areas with high intensity values ​​(noise areas) other than the iron ores O1 and O2 to be sorted in the image of the iron ores to be sorted, an anti-reflection sheet or the like that suppresses light reflection may be placed in the background, as necessary.

[0039] (Extraction step ST23) In extraction step ST23, the intensity value of the B component from among the RGB components of the image to be selected is extracted using the arithmetic control means 30. If the image to be selected is an 8-bit image, the intensity value of the B component will be 0 for the darkest value and 255 for the brightest value, and is extracted for each pixel constituting the image to be selected.

[0040] (Sorting step ST24) In the sorting step ST24, the calculation control means 30 classifies the iron ores O1 and O2 into two categories: a first category of iron ores corresponding to pixel regions in the sorting target image where the intensity value of the B component is equal to or greater than the threshold value Th, and a second category of iron ores corresponding to pixel regions in the sorting target image where the intensity value of the B component is less than the threshold value Th. The iron ores in the first category are expected to be white-colored iron ores O1. The iron ores in the second category are expected to be other-colored iron ores O2. In the sorting target step ST24 of this embodiment, if the same pixel region (a pixel region that can be considered to correspond to one sorting target iron ore) contains a mixture of pixels whose intensity value of the B component is greater than or equal to the threshold value Th and pixels whose intensity value of the B component is less than the threshold value Th, if there is at least one pixel whose intensity value of the B component is greater than or equal to the threshold value Th, the pixel region is considered to be a pixel region whose intensity value of the B component is greater than or equal to the threshold value Th, and the sorting target iron ore corresponding to this pixel region is classified as the first category of sorting target iron ore.

[0041] Then, in the sorting step ST24, the two sorted categories of iron ore to be sorted are sorted using the arithmetic and control means 30 and the air gun 40. In the example shown in Fig. 1, as described above, the first category of iron ore to be sorted, which is expected to be white iron ore to be sorted O1, is blown by the air gun 40 and sorted and transported onto the conveyor 10c, while the second category of iron ore to be sorted, which is expected to be other-color iron ore to be sorted O2, is not blown by the air gun 40 but is sorted and transported onto the conveyor 10b. In the first embodiment, an example of performing the sorting step ST24 using the sorting device 100 shown in Figure 1 has been described, but the present invention is not limited to this, and the sorting step ST24 can be performed using sorting devices having various configurations as long as they are capable of sorting the two classified categories of iron ore to be sorted.

[0042] (Sorting step ST25) In the sorting step ST25, the second-class iron ore sorted on the conveyor 10b is sorted to the sintering process. That is, the second-class iron ore sorted is transported to the sintering process by the conveyor 10b or the like. The second-class iron ore sorted is expected to be multi-colored iron ore with a small amount of gangue components. Therefore, by sorting the second-class iron ore sorted to the sintering process, it is possible to sort iron ore with a small amount of gangue components to the sintering process. Meanwhile, in the sorting step ST25, the first-class iron ore sorted on the conveyor 10a is sorted to the iron ore crushing step ST3. That is, the first-class iron ore sorted on the conveyor 10a or the like is transported to the iron ore crushing step ST3.

[0043] [Iron ore crushing process ST3] In the iron ore crushing step ST3, the first division of iron ore to be sorted is crushed, and as shown in Fig. 2, the entire amount of the crushed first division of iron ore to be sorted is subjected to the sintering step. Specifically, in the iron ore crushing step ST3, the first category of iron ore to be sorted is crushed finely to a particle size of approximately 1 mm or less, and then mixed with the second category of iron ore to be sorted in the sintering step, and sintered together. In addition, in the iron ore crushing step ST3, the first-class iron ore to be sorted may be crushed finely to a particle size of approximately 1 mm or less, subjected to a granulation process using a pan pelletizer in the sintering step, and then subjected to a sintering treatment. Furthermore, in the iron ore crushing step ST3, the first-class iron ore to be sorted may be crushed in a vertical wet mill and used as a fine particle binder in the granulation process in the sintering step. In addition, if the sorting process ST2 of the first embodiment is not performed and not only the first-class iron ore to be sorted but also the second-class iron ore to be sorted, which is expected to be other-color iron ore O2 mainly composed of iron oxide, is crushed in the iron ore crushing process ST3, there is a disadvantage that the granulation properties in the granulation process of the sintering process will deteriorate, and ultimately productivity will decrease. As in the first embodiment, by performing the iron ore crushing process ST3, the melting and assimilation properties of the first division of iron ore to be sorted after crushing are improved compared to before crushing, and deterioration in sintering productivity can be reduced, which has the advantage of allowing the first division of iron ore to be sorted to be effectively utilized.

[0044] <<Second embodiment>> FIG. 4 is a flowchart showing an outline of the procedure of the sorting method according to the second embodiment. 4, the sorting method according to the second embodiment also includes a threshold value determination step ST1, a sorting step ST2, and an iron ore crushing step ST3, similar to the sorting method according to the first embodiment. The method according to the second embodiment differs from the first embodiment in that it further includes an ore-dressing processing step ST4. Hereinafter, explanation of the steps ST1 to ST3 which are the same as those in the first embodiment will be omitted, and only the ore dressing step ST4 which is different from the first embodiment will be explained.

[0045] [Ore dressing process ST4] In the ore dressing process ST4, the first-class iron ore to be sorted, which has been crushed in the iron ore crushing process ST3, is separated into particles mainly composed of iron-bearing minerals and particles mainly composed of gangue using a dressing process. Examples of the dressing process include gravity dressing, flotation, and magnetic separation. As shown in Figure 4, the separated particles mainly composed of iron-bearing minerals are subjected to a sintering process, and the separated particles mainly composed of gangue are disposed of.

[0046] According to the sorting method of the second embodiment, the iron ore to be sorted in the first division, which is expected to be white iron ore containing a large amount of gangue, is crushed in the iron ore crushing step ST3. Then, in the ore dressing step ST4, the crushed first division of the iron ore to be sorted is separated and sorted into particles mainly composed of iron-bearing minerals and particles mainly composed of gangue using a dressing method. The particles mainly composed of iron-bearing minerals are then subjected to a sintering step, while the particles mainly composed of gangue are discarded. This allows for effective use of the particles mainly composed of iron-bearing minerals from the first division of the iron ore to be sorted, and by discarding the particles mainly composed of gangue, which inhibit melting and assimilation in the sintering step, it is possible to reduce deterioration in sintering productivity.

[0047] <Example> An example of the threshold value determination step ST1 will be described below. In this example, a sample extracted from Australian iron ore A, which was the iron ore to be sorted, was used as the threshold determination iron ore. Iron ore A was classified using a sieve to prepare threshold determination iron ore with a particle size of 4.75 mm or more and less than 9.5 mm. Approximately 150 to 200 g of the classified threshold determination iron ore was placed in a beaker or tray and placed in a tabletop ultrasonic cleaner. Water was added until the threshold determination iron ore was completely immersed, and the mixture was vibrated for several minutes to remove fine particles adhering to the surface of the threshold determination iron ore. The threshold determination iron ore was then removed from the ultrasonic cleaner and placed in a dryer where it was dried at 105°C for at least two hours.

[0048] Next, the washed and dried iron ores for threshold determination were visually classified into two categories of iron ores for threshold determination: white iron ore for threshold determination O1 and other color iron ores for threshold determination O2. Then, threshold determination images were acquired for each of the two categories of iron ores for threshold determination O1 and O2. The aforementioned FIG. 3(a) shows images of threshold determination iron ores O1 and O2, which are made of iron ore A and have a particle size of 4.75 mm or more and less than 9.5 mm, captured under light irradiation from a neutral white LED light source. (In the aforementioned second determination mode, an image like that shown in FIG. 3(a) is used as the threshold determination image. However, in this embodiment, the threshold is determined under the first determination mode, so the image like that shown in FIG. 3(a) is not used as the threshold determination image.) The aforementioned FIG. 3(b) shows a threshold determination image of a classified threshold determination iron ore O1, which is made of iron ore A and has a particle size of 4.75 mm or more and less than 9.5 mm, captured under light irradiation from a neutral white LED light source. Although not shown, a threshold determination image of a classified threshold determination iron ore O2, which is made of iron ore A and has a particle size of 4.75 mm or more and less than 9.5 mm, captured under light irradiation from a neutral white LED light source was also prepared. As shown in Figure 3(b), iron ore O1 for determining the whiteness threshold was selected from iron ore that was visually determined to contain a certain amount of white ore. As can be seen in Figure 1(a), iron-containing minerals such as magnetite (Fe3O4), hematite (Fe2O3), and goethite (FeOOH), which are the main minerals in iron ore, exhibit external colors other than white, such as black, gray, red, and yellow. However, the white color is thought to be derived from gangue components that do not contain iron.

[0049] Next, the calculation control means 30 was used to randomly perform point analysis (pixel-by-pixel analysis) on the colored portions of the threshold determination iron ores O1 and O2 (excluding the white color) on the image shown in Fig. 3(a), and a total of 120 points (pixels) of intensity values ​​for each RGB component were calculated. Similarly, for the threshold determination image shown in Fig. 3(b), point analysis (pixel-by-pixel analysis) was randomly performed on the white portion of the threshold determination iron ore O1, and a total of 40 points (pixels) of intensity values ​​for each RGB component were calculated. Figure 5 shows the results of the point analysis. Figure 5(a) shows the results in a graph, and Figure 5(b) shows the results in a table. In Figure 5(a), the points plotted with "◇" and "▲" indicate the average intensity values, and the bars extending above and below each plotted point indicate the standard deviation. As can be seen from Figure 5(a), in the white portion, the average values ​​of the intensity values ​​of each of the RGB components are large, while in the other color portions, the average values ​​of the intensity values ​​decrease in the order of the R component, the G component, and the B component. Also, as can be seen from Figure 5(b), in the R and G components, the maximum value of the intensity values ​​in the other color portions is greater than the minimum value of the intensity values ​​in the white portion (i.e., the variation in the intensity values ​​in the white portion and the variation in the intensity values ​​in the other color portions overlap), but in the B component, the minimum value of the intensity value in the white portion is greater than the maximum value of the intensity values ​​in the other color portions (i.e., the variation in the intensity values ​​in the white portion and the variation in the intensity values ​​in the other color portions do not overlap). Therefore, if the intensity value of the B component is extracted, it is expected that it will be easier to classify and separate white iron ore with a high gangue content from other colored iron ore with a low gangue content, depending on its magnitude.

[0050] Next, the calculation control means 30 was used to calculate the intensity value of the B component of the pixel region corresponding to the threshold determination iron ore O1 in the threshold determination image acquired for the threshold determination iron ore O1 shown in Figure 3(b), and the intensity value of the B component of the pixel region corresponding to the threshold determination iron ore O1 in the threshold determination image (not shown) acquired for the threshold determination iron ore O2. For the threshold determination image shown in Figure 3(b), the background area other than the threshold determination iron ore O1 was erased (intensity value = 0) as shown in Figure 6(a), and the intensity value of the B component of the pixel region corresponding to the threshold determination iron ore O1 was calculated as a value from 0 (darkest) to 255 (brightest) as shown in Figure 6(b). The same was true for the threshold determination image acquired for the threshold determination iron ore O2.

[0051] Then, for each threshold determination image, the distribution (histogram) of the intensity values ​​of the B component in the pixel regions corresponding to the threshold determination iron ores O1 and O2 was calculated. FIG. 7 shows the distribution of B component intensity values ​​in pixel regions corresponding to threshold determination iron ores in a threshold determination image. FIG. 7(a) shows the distribution of B component intensity values ​​for a white threshold determination iron ore O1, and FIG. 7(b) shows the distribution of B component intensity values ​​for a different color threshold determination iron ore O2. The horizontal axis in FIG. 7 has a lower limit of 10 intensity value so as not to include background areas. In both FIG. 7(a) and FIG. 7(b), it can be seen that the peak intensity values ​​are in the range of 35 or more and less than 59. Therefore, the peak intensity value is set to, for example, 47, which is an intermediate value. As can be seen from Figure 7(a), the white-colored iron ore O1 for threshold determination contained approximately 35% intensity values ​​of 84 or higher and approximately 20% intensity values ​​of 108 or higher, whereas as can be seen from Figure 7(b), the other-colored iron ore O2 for threshold determination contained almost no intensity values, at approximately 3% intensity values ​​of 84 or higher and approximately 0.1% intensity values ​​of 108 or higher. Therefore, for example, if the threshold value Th is set to 108, which is an intensity value approximately 60 times greater than the peak intensity value, the white-colored iron ore O1 for threshold determination will be appropriately classified and sorted as iron ore to be sorted in the first category corresponding to the pixel region in the sorting target image where the intensity value of the B component is equal to or greater than the threshold value Th (the possibility that the other-colored iron ore O2 for threshold determination will be erroneously classified and sorted as iron ore to be sorted in the first category is expected to be approximately 0.1%).

[0052] In this example, the components of the iron ores O1 and O2 used to determine the threshold values ​​were also analyzed based on "JIS M 8202" (iron ore - general rules for analytical methods), "JIS M 8206" (iron ore - ICP atomic emission spectrometry), "JIS M 8211" (iron ore - quantitative determination of water of synthesis), and "JIS M 8212 (iron ore - quantitative determination of total iron)." Table 1 below shows the results of the above component analysis. [Table 1] As shown in Table 1, the white iron ore O1 for determining the threshold contains a large amount of SiO2 and Al2O3, and is therefore thought to contain a relatively large amount of gangue components. [Explanation of symbols]

[0053] 10. Conveyor 20. Imaging means 30. Operation and control means 40... air gun 100...Sorting device ST1: Threshold determination step ST2: Sorting process ST3: Iron ore crushing process ST4: Mineral processing process

Claims

1. a threshold determination step of determining a threshold value for the intensity value of the B component of the RGB components of a threshold determination image, which is a color image of an iron ore for threshold determination that is the same type of iron ore as the iron ore to be sorted; A sorting process of classifying and sorting the iron ore to be sorted into two categories using a sorting target image, which is a color image of the iron ore to be sorted, and the threshold value, The threshold value determination step includes: an image acquisition step of capturing an image of the iron ore for threshold determination to acquire the image for threshold determination; an extraction step of extracting an intensity value of the B component from among the RGB components of the threshold determination image; a determining step of determining, as the threshold value, an intensity value that is larger by a predetermined value than a peak intensity value of a distribution of intensity values ​​of the B component in a pixel region corresponding to the threshold value determination iron ore in the threshold value determination image, The selection step includes: an image acquisition step of capturing an image of the iron ore to be sorted to acquire the image of the iron ore to be sorted; an extraction step of extracting an intensity value of a B component from among the RGB components of the image to be selected; A sorting step of classifying and sorting the iron ore to be sorted into two categories: a first category of iron ore to be sorted corresponding to pixel areas in the sorting target image where the intensity value of the B component is equal to or greater than the threshold value, and a second category of iron ore to be sorted corresponding to pixel areas in the sorting target image where the intensity value of the B component is less than the threshold value; A sorting step of sorting the second sorting target iron ore sorted in the sorting step to a sintering process, Iron ore sorting method.

2. The method further comprises the steps of crushing iron ore, In the sorting step of the sorting process, the first classification of sorting target iron ore sorted in the sorting step is sorted to the iron ore crushing step, In the iron ore crushing step, the first classification iron ore to be sorted is crushed, The entire amount of the crushed first-class iron ore to be sorted is subjected to the sintering step. The method for separating iron ore according to claim 1.

3. The entire amount of the crushed first-class iron ore to be sorted is subjected to a granulation process using a pan pelletizer in the sintering step. The method for separating iron ore according to claim 2.

4. The method further includes an iron ore crushing step and an ore dressing step, In the sorting step of the sorting process, the first classification of sorting target iron ore sorted in the sorting step is sorted to the iron ore crushing step, In the iron ore crushing step, the first classification iron ore to be sorted is crushed, In the ore-dressing process, the crushed first-class iron ore to be sorted is separated and sorted into particles mainly composed of iron-bearing minerals and particles mainly composed of gangue using an ore-dressing process; The separated and sorted particles mainly composed of iron-bearing minerals are subjected to the sintering step, and the separated and sorted particles mainly composed of gangue are disposed of as waste. The method for separating iron ore according to claim 1.

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