Bubble measurement device and bubble measurement method

Abstract

This bubble measurement device for measuring bubbles moving in a liquid, is provided with: a measurement chamber to which bubbles in a liquid containing solid matter are introduced from the lower side and which is provided with a transparent inclined surface oriented obliquely downward at a position where the introduced bubbles ascend; an imaging device that captures an image of the bubbles passing along the transparent inclined surface; an introduction pipe that is disposed below the measurement chamber and that introduces bubbles to the measurement chamber; and a bubble introduction valve that is immersed in the liquid to be measured and that blocks and introduces bubbles to the introduction pipe. The opening time period of the bubble introduction valve is obtained in accordance with the shape of the introduction pipe, the properties of the liquid, and the supply amount of air supplied into the liquid. When the imaging device captures an image of bubbles in the measurement chamber, the opening time period of the bubble introduction valve is adjusted to a predetermined time period in which the bubbles and the solid matter contained in the liquid can be identified.

Description

Technical Field

[0001] The present invention relates to a bubble measuring device and a bubble measuring method.

Background Art

[0002] In the beneficiation for separating useful metals, the flotation method (hereinafter also referred to as flotation), which is widely used, is a method of attaching hydrophobic useful metal particles to bubbles in a solution to separate them from unwanted minerals. One of the flotation machines for performing this separation is an agitator type flotation machine.

[0003] In flotation, the contact between mineral particles and bubbles in the ore slurry is an important mechanism. Regarding the contact probability, it is known that the bubble diameter is an important factor, and attempts have been made to grasp the bubble diameter. For bubbles generated in liquids containing no solids such as fresh water and seawater, there are many reports of examples in which the diameter was measured by introducing them into a measurement chamber together with the liquid and performing backlight photography.

[0004] As a method for performing clear photography, for example, the method shown in Patent Document 1 is disclosed. The method shown in Patent Document 1 discloses a method of collecting bubbles in a slurry by opening an air-driven valve for a predetermined time.

[0005] However, in the configuration described in Patent Document 1, turbidity flows into the apparatus slightly later than the bubbles or almost simultaneously with the bubbles, so the transparency of the liquid is extremely low, making it difficult to take clear photographs, and in the photographed image, the bubbles are indistinguishable from the mineral particles, making it difficult to identify them.

[0006] In addition, in a flotation machine, air is introduced into a flotation cell in which slurry is stored to generate bubbles, and useful metals are attached to the generated bubbles. In order to perform this flotation efficiently, it is required to appropriately grasp the size and quantity of the generated bubbles and put them in an appropriate state.

[0007] As a method for appropriately grasping the size and quantity of generated bubbles, for example, many methods for measuring the bubble diameter distribution by means of backlight photography have been reported. However, these are methods for measuring bubbles generated in liquids that do not contain solid particles, such as fresh water or seawater, and are not methods for measuring bubbles generated in ore slurries where the transparency of the liquid is extremely low and clear photography is difficult. Thus, there is a demand for a more advantageous method that can perform clear photography even in an ore slurry with extremely low liquid transparency.

[0008] As a method for performing clear photography, for example, the method disclosed in Patent Document 1 is disclosed. The method disclosed in Patent Document 1 discloses a method of collecting bubbles in a slurry by opening an air-driven valve for a predetermined time. However, since turbidity flows into the apparatus slightly later than the bubbles or almost simultaneously with the bubbles, there are problems such as being able to photograph only for a short time and being unable to perform repeated photography. Further, the turbidity that has flowed into the apparatus needs to be removed by cleaning after removing the apparatus from the slurry, which is inefficient.

[0009] By the way, in flotation, bubbles with a small bubble diameter can be used, and thereby the yield can be improved. In particular, bubbles with a bubble diameter of 1 to 100 μm are expected to have the potential for application to flotation.

[0010] However, since the above-mentioned minute bubbles have high adhesiveness, there has been a problem that they adhere to the bubble diameter measuring device, and it has been impossible to appropriately grasp the size and quantity of the generated bubbles.

[0011] As a method for dealing with this problem, for example, the method disclosed in Patent Document 2 is disclosed. The method disclosed in Patent Document 2 is a method of providing a film for preventing bubble adhesion in a chamber and introducing a water flow into this chamber. However, also in this method, no countermeasure against turbidity is taken, and a method that can effectively function as a measurement system practical in a flotation process or a minute bubble generation process is not disclosed.

Prior Art Documents

Patent Document

[0012]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0013] Therefore, an object of the present invention is to provide a bubble measuring device and a bubble measuring method capable of eliminating the influence of ore slurry, clearly photographing bubbles, and accurately measuring the bubble diameter.

[0014] Further, in order to solve the situation where it is impossible to appropriately grasp the size and quantity of generated bubbles, the present invention can perform clear photography even when targeting a liquid containing solid particles, and can appropriately grasp the size and quantity of generated bubbles even when targeting a liquid containing minute bubbles, and also provide a bubble measuring device and a bubble measuring method capable of performing efficient photography.

Means for Solving the Problems

[0015] To achieve the above object, a bubble measuring method according to an aspect of the present invention introduces bubbles in a liquid containing solids from below, and at a position where the introduced bubbles rise, there is a measurement chamber provided with a transparent inclined surface facing obliquely downward, a photographing device that photographs the bubbles passing through the transparent inclined surface, an introduction pipe provided below the measurement chamber for introducing the bubbles into the measurement chamber, a bubble introduction valve immersed in the liquid to be measured for introducing and blocking the bubbles into the introduction pipe, and is a bubble measuring method using a bubble measuring device including The photographing device photographs the bubbles, and obtains the introduction time of the bubbles into the introduction pipe such that the bubbles contained in the liquid and the solid matter can be distinguished, according to the shape of the introduction pipe, the properties of the liquid, and the supply amount of the air supplied into the liquid. The opening time of the bubble introduction valve is adjusted to the introduction time of the bubbles into the introduction pipe at which the obtained bubbles and the solid matter can be distinguished, and the bubbles are measured.

[0016] Further, in order to achieve the above object, a bubble measuring device according to an aspect of the present invention is a bubble measuring device that measures bubbles moving in a liquid, a measurement chamber that holds the liquid, introduces the bubbles in the liquid from below, and is provided with a transparent inclined surface facing obliquely downward at a position where the introduced bubbles rise; a photographing device that photographs the bubbles passing through the transparent inclined surface; an introduction pipe that is provided below the measurement chamber and introduces the bubbles into the measurement chamber; a bubble introduction valve that is immersed in a liquid containing bubbles to be measured and opens and closes the introduction of the bubbles into the introduction pipe; a first on-off valve that is provided above the measurement chamber and shuts off the supply or discharge of the observation solution to the measurement chamber; a second on-off valve that is provided below the measurement chamber and shuts off the supply or discharge of the observation solution to the measurement chamber, and is characterized by including the same.

Advantages of the Invention

[0017] According to the present invention, the influence of turbidity caused by ore slurry can be suppressed, and bubbles can be reliably measured.

[0018] Further, according to the present invention, clear photographing can be performed even when the target is a liquid containing solid particles, and efficient photographing can be performed even when the target is a liquid containing minute bubbles, and the size and quantity of the generated bubbles can be appropriately grasped.

Brief Description of the Drawings

[0019]

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Embodiments for Carrying Out the Invention

[0020] Hereinafter, with reference to the drawings, embodiments for carrying out the present invention will be described.

[0021] [First Embodiment] FIG. 1 is a schematic diagram showing the configuration of a bubble measuring device according to a first embodiment of the present invention and a flotation machine to which the bubble measuring device is applied. The bubble measuring device according to the first embodiment of the present invention includes a bubble introduction valve 50, an introduction pipe 60, a frame 70, a measurement chamber 80, a light projecting device 90, a photographing device 100, and an upper valve 110. Further, if necessary, an air source 120, an on-off solenoid valve 130, and a control unit 140 may be provided.

[0022] The flotation machine 40 to which the bubble measuring device according to the present embodiment is applied includes a flotation cell 10, an air supply shaft 20, and an agitation blade 30. Further, as related components of the flotation machine 40 and the bubble measuring device, an ore slurry 150 is stored in the flotation cell 10.

[0023] As the flotation machine 40 according to the present embodiment, various generally used flotation machines can be used. For example, an agitator type flotation machine or a Denver type flotation machine may be used.

[0024] The flotation cell 10 is a slurry storage means for storing a liquid ore slurry 150 containing pulverized matter to be beneficiated. The ore slurry 150 is composed of ore and liquid. Air is supplied into the ore slurry 150, and the air becomes bubbles to float the ore, thereby performing flotation beneficiation to collect useful metals.

[0025] The air supply shaft 20 is an air supply means for supplying air (air) from the lower end. As described above, by supplying air into the ore slurry 150, bubbles for floating the ore are generated. For example, the lower end of the air supply shaft 20 is disposed near the bottom surface of the flotation cell 10, and bubbles are generated from near the bottom surface of the flotation cell 10.

[0026] The stirring blade 30 is a bubble refinement means for making the bubbles generated by the air supplied from the lower end of the air supply shaft 20 finer. The bubbles generated at the lower end of the air supply shaft 20, that is, the central part of the stirring blade 30, collide with the stirring blade 30 due to the rotation of the stirring blade 30 when being discharged from the stirring blade 30, whereby the bubble diameter becomes smaller.

[0027] Since the diameter, number density, etc. of the bubbles affect the flotation performance, it is important to measure and manage the bubbles in order to improve the flotation performance. The bubble measuring device according to the present embodiment is used to measure the bubble diameter, bubble density, etc.

[0028] The bubble measuring device is provided with a bubble introduction valve 50 at the lower end and has an introduction pipe 60 above it. A frame 70 is provided at the upper end of the introduction pipe 60, and a measurement chamber 80, a photographing device 100, and a light projecting device 90 are provided on the frame 70. An upper valve 110 is provided above the measurement chamber 80. Further, when the bubble introduction valve 50 is, for example, air-driven, an air source 120, an on-off solenoid valve 130, and a control unit 140 for driving the on-off solenoid valve 130 to open and close are provided as necessary.

[0029] The measurement of the bubbles is specifically performed as follows.

[0030] First, the bubbles floating up from the bubble introduction valve 50 are introduced, and the introduced bubbles are introduced into the measurement chamber 80 via the introduction pipe 60. The measurement chamber 80 is irradiated with light from the light projecting device 90, the photographing device 100 photographs the bubbles in the measurement chamber 80, information necessary for measuring the bubble diameter, the number density of the bubbles, etc. is obtained from the photographed image, and those values are measured. In the bubble measurement, the measurement chamber 80 is initially filled with a transparent liquid, but since the ore slurry is also introduced when the bubbles are introduced, the inside of the measurement chamber 80 becomes turbid. If the degree of turbidity is large, it becomes difficult to distinguish between the bubbles and the ore (solid matter), and it becomes difficult to accurately measure the bubbles.

[0031] Therefore, in the bubble measurement method and the bubble measurement apparatus according to the present embodiment, a bubble measurement method and a bubble measurement apparatus that suppress such turbidity are provided.

[0032] Hereinafter, details of the components constituting the bubble measurement apparatus according to the present embodiment will be described.

[0033] (Bubble introduction valve) In the present embodiment, the bubble introduction valve 50 is a valve body that can switch between a state in which a liquid containing solids, that is, the ore slurry 150, can move and a state in which the movement of the ore slurry 150 is blocked. The bubble introduction valve 50 is attached to the lower end of the introduction pipe 60 and is a part that is immersed in the liquid to be measured.

[0034] Furthermore, the bubble introduction valve 50 is preferably a valve body through which the flow path passes when the valve is opened. Thereby, it is possible to effectively prevent bubbles from staying inside the valve body. Examples of valves that satisfy such requirements include mechanical valves such as ball valves, gate valves, and butterfly valves, as well as air expansion valves having an elastic deformation member inside.

[0035] In the bubble measurement apparatus according to the present embodiment, the opening time of the bubble introduction valve 50 is adjusted so that the amount of the ore slurry 150 introduced into the measurement chamber 80 is within an amount that does not interfere with the photographing of bubbles. That is, instead of keeping the bubble introduction valve 50 open continuously, it is opened for a certain period of time, and bubbles are introduced only for that opening time, and the measurement of bubbles is performed in the measurement chamber 80.

[0036] The adjustment of the opening time is performed according to the shape of the introduction pipe 60, the properties of the liquid constituting the ore slurry 150, and the supply amount of the air supplied into the liquid. Details thereof will be described later.

[0037] (Introduction pipe) In the present embodiment, the introduction pipe 60 is a pipe material having a cylindrical cross-section with both ends open. A bubble introduction valve 50 is attached to the end of the introduction pipe 60 on the side immersed in the liquid, and an introduction pipe connection member 81 is attached to the end of the introduction pipe 60 on the measurement chamber 80 side.

[0038] The shape of the introduction pipe 60 is a major factor in determining how much of the solids in the ore slurry 150 reach the measurement chamber 80. If the introduction pipe 60 is sufficiently long, it is possible to suppress the amount of solids in the ore slurry 150, particularly particles with a particle size smaller than the lower limit of the identification limit value of the imaging device, that reach the measurement chamber 80. That is, since the path from the bubble introduction valve 50 to the measurement chamber 80 becomes longer, it becomes difficult for the solids to reach the measurement chamber 80, and turbidity in the measurement chamber 80 can be suppressed.

[0039] Specific values that can sufficiently suppress the solids in the ore slurry 150 from reaching the measurement chamber 80 will be described later.

[0040] (Measurement chamber) FIG. 2 is an enlarged view of the measurement chamber 80. FIG. 2(a) is a side view of the measurement chamber 80, and FIG. 2(b) is a front view of the measurement chamber 80.

[0041] In the present embodiment, the measurement chamber 80 is composed of a plurality of transparent members. In this embodiment, the material of these members is vinyl chloride. As the material of the members, members with a high light transmittance can be preferably used so that the light projected from the light projecting device 90 can pass through the measurement chamber 80 and be measured by the imaging device 100. The light transmittance of the members is preferably 80% or more, more preferably 90% or more, in the visible light region of wavelengths 400 nm to 700 mm.

[0042] In addition to vinyl chloride, glass, acrylic, polyethylene terephthalate (PET), polycarbonate, etc. can be used as the members that satisfy the above-described optical characteristics.

[0043] Vinyl chloride can be suitably used as a member of the measurement chamber 80 because it is inexpensive, highly processable, and highly transparent. In addition, acrylic has higher transparency than vinyl chloride, is less likely to be scratched, and has less reduction in transparency, so it can be suitably used for installation in places where replacement is difficult.

[0044] In the measurement chamber 80, a main member 82, a first lid member 83, and a second lid member 84 are provided so as to sandwich the main member 82. The outer shape of the main member 82 is a thick square plate shape, that is, a flat square prism shape. A measurement hole 82a with a relatively large diameter is provided in the main member 82. The axial direction of this measurement hole 82a coincides with the thickness direction of the thinnest thickness of the square prism form of the main member 82 (hereinafter this direction may be referred to as the thickness direction of the main member 82). By sandwiching the main member 82 between the first lid member 83 and the second lid member 84 so as to close the measurement hole 82a, the portion of the measurement hole 82a becomes a space closed in the axial direction of the measurement hole 82a.

[0045] Here, among the spaces formed by the main member 82, the first lid member 83, and the second lid member 84, the right side surface of the first lid member 83 is referred to as a transparent inclined surface, and the portion of this transparent inclined surface where the measurement hole 82a is located is referred to as a measurement part 83a.

[0046] The measurement chamber 80 further includes an introduction pipe connection member 81 provided below the main member 82 and a lead-out pipe 85 provided above the main member 82, and the introduction pipe 60 is connected via the introduction pipe connection member 81. Here, since the introduction pipe connection member 81 has a through hole and both the introduction pipe 81 and the lead-out pipe 85 have a cylindrical structure, through these members, the measurement chamber 80 has a vertically communicating structure. By being connected in this way, it is possible to hold liquid in the measurement chamber 80 and to introduce air bubbles in the liquid from the introduction pipe 60.

[0047] The introduction pipe 60 connected to the introduction pipe connection member 81 is arranged such that the axis of the inner surface of the pipe is in the vertical direction. Further, the upper surface of the introduction pipe connection member 81 connected to this introduction pipe 60 is inclined by an inclination angle θ from the horizontal plane. Due to the inclination of the upper surface of the introduction pipe connection member 81 in this way, the transparent inclined surface including the measurement unit 83a is inclined by the inclination angle θ from the vertical. That is, the normal line of the transparent inclined surface faces downward, and the transparent inclined surface is in a posture facing obliquely downward. The inclination angle θ is determined such that the transparent inclined surface is positioned at the position where the bubbles rising from the introduction port come. In this embodiment, the inclination angle θ is 15 degrees, but it may be set to various angles according to the application. Note that by inclining the measurement unit 83a, it is possible to photograph the bubbles in a state where focus is adjusted for all the bubbles.

[0048] Due to the transparent inclined surface being inclined by the inclination angle θ, the bubbles that have risen in the liquid come into contact with the transparent inclined surface including the measurement unit 83a, and in the case of bubbles having a certain size or more, the bubbles rise along this transparent inclined surface. By the bubbles rising in this way, it is possible to prevent the bubbles from overlapping, so that the size and quantity of the bubbles can be accurately measured. At this time, there is almost no movement of the liquid containing the bubbles.

[0049] The diameter L1 of the measurement hole 82a of the main member 82 constituting the bubble measurement device of this embodiment is longer than the diameter of the inner surface of the introduction pipe 60. Here, the diameter L1 of the measurement hole 82a is the length in the left - right direction of the measurement unit 83a when the transparent inclined surface is viewed from the front.

[0050] Further, the main member 82 is provided with the measurement hole 82a as described above, and an enlarged communication portion for communicating the measurement hole 82a and the introduction pipe 60 is provided. The enlarged communication portion is in a groove shape. The length in the left - right direction from the groove portion of the enlarged communication portion to the measurement unit 83a increases at a certain ratio from the lower side to the upper side. The depth of the groove shape of the enlarged communication portion has a depth of 1 / 3 of the length in the thickness direction of the main member 82.

[0051] (Light - projecting device and photographing device) The light projection device 90 irradiates the measurement unit 83a with light of a predetermined type from one surface of the measurement chamber 80. This facilitates imaging inside the measurement chamber 80. As the illumination means, for example, surface illumination such as white LEDs is preferably used.

[0052] The imaging device 100 is preferably a digital camera or the like that can capture at least either still images or moving images. The size and quantity of the bubbles captured by this imaging device 100 are preferably analyzed by software that performs image processing. The imaging device 100 may use various imaging devices as long as it can appropriately capture the bubbles. For example, the imaging device 100 may use a device with a shooting speed of 3.3 fps and capable of continuous shooting.

[0053] (Other components) The frame 70 is a support member for supporting the measurement chamber 80, the light projection device 90, and the imaging device 100.

[0054] The upper valve 110 is a valve for introducing and discharging the transparent liquid inside the measurement chamber 80, and may be composed of, for example, a manual valve. The transparent liquid supplied into the measurement chamber 80 during measurement may be, for example, water (fresh water or seawater) with a foaming agent added. The foaming agent may be added, for example, at the same concentration as the liquid inside the flotation machine.

[0055] The upper valve 110 can use various valves according to the application, and an automatic valve may be used as needed.

[0056] The air source 120 is a drive source when driving the bubble introduction valve 50 by air. The on-off solenoid valve 130 is a solenoid valve for driving the bubble introduction valve 50 to open and close, and is controlled to open and close, for example, by the control unit 140. When the on-off solenoid valve 130 is opened, air is supplied from the air source 120 to the bubble introduction valve 50, and the bubble introduction valve 50 opens or closes. The air source 120 may be a compressed air supply source that supplies compressed air.

[0057] The control unit 140 is a means for controlling the operations of the flotation machine 40 and the bubble measurement device, and may be configured as, for example, a microcomputer. The control unit 140 controls, for example, the operation of the on-off solenoid valve 130 and the imaging operation of the imaging device 100. Further, the control unit 140 may incorporate an image processing unit and perform image processing on the image captured by the imaging device 100. Although not shown in FIG. 1, the image processing unit may be provided separately from the control unit 140, perform image processing on the image captured by the imaging device 100, and transmit the processed image to the control unit 140. Such a system configuration can be variously configured according to the application.

[0058] Note that the control operation of the bubble introduction valve 50 is not essential, and the bubble introduction valve 50 may be configured to periodically perform an opening operation for a set predetermined time, or may be manual as long as a manual opening operation for a predetermined time is possible.

[0059] Next, a bubble measurement method using the bubble measurement device according to the present embodiment will be described.

[0060] First, a conventional bubble measurement method will be described with reference to FIG. 3. FIG. 3 is a diagram for explaining a conventional bubble measurement method.

[0061] As shown in FIG. 3, conventionally, the bubble introduction valve 50 has been always open to measure the bubbles 151 in the measurement chamber 280. Then, the ore slurry 150 may mix into the lower part of the measurement chamber 280, and the liquid 160 in the measurement chamber 280 may become turbid, making it difficult to recognize the bubbles 151 by image recognition.

[0062] FIG. 4 is a diagram showing an image with turbidity by a conventional bubble measurement method. In an image as shown in FIG. 4, it is impossible to distinguish the turbidity caused by the bubbles 151 and the ore slurry 150 by image processing, making it difficult to identify the bubbles 151 and accurately measure the bubbles.

[0063] FIG. 5 is a diagram showing an example of the bubble measurement method according to the present embodiment. As shown in FIG. 5, in the bubble measurement method according to the present embodiment, after opening the bubble introduction valve 50 to introduce the bubbles 151 into the measurement chamber 80, the bubble introduction valve 50 is sealed to prevent the ore slurry 150 from entering the measurement chamber 80. Thereby, the transparent liquid 160 does not become turbid, and the bubbles 151 can be accurately measured.

[0064] However, if only the opening time of the bubble introduction valve 50 is simply limited, an image capable of sufficiently identifying the bubbles may not be obtained unless the opening time of the bubble introduction valve 50 is made considerably short. Also, if the opening time of the bubble introduction valve 50 is too short, there is a risk that the bubbles cannot be measured sufficiently.

[0065] Therefore, in the present embodiment, an appropriate opening time of the bubble introduction valve 50 is adjusted and set according to the shape of the introduction pipe 60, the properties of the liquid constituting the ore slurry 150, and the supply amount of the air supplied from the air supply shaft 20. Thereby, while increasing the opening time of the bubble introduction valve 50, the measurement of the bubbles 151 can be appropriately performed. The details will be described below.

[0066] First, in order to distinguish the bubbles 151 from the solids, there is a size (discrimination limit value) that serves as the discrimination limit according to the resolution of the imaging device 100 used. The discrimination limit value will be described below.

[0067] FIG. 6 is a diagram for explaining the resolution of the digital camera, and shows a state where the bubbles 151 are photographed. As shown in FIG. 4, the bubbles 151 often have a shape approximated to a circle or an ellipse, and 4×4 = 16 pixels are required to recognize the bubbles 151. If these 16 pixels are recognized with binary 1 or 0 and photographed, these 16 pixels become 1, and the surrounding becomes 0, and the bubbles 151 are recognized as a rectangle as an image. That is, when the rectangular shape can be recognized, it can be determined that the bubbles 151 have been imaged.

[0068] FIG. 7 is a diagram showing a state in which the mineral 152 is photographed with a digital camera. As shown in FIG. 7, the mineral 152 has an irregular shape with irregularities, and the corresponding pixels (regions recognized as 1) also have an irregular shape with irregularities. As described above, in the case of the air bubble 151, it is recognized as having a square or rectangular shape, but since the mineral 152 is recognized as having an irregular shape with irregularities, it is possible to distinguish and recognize that it is the mineral 152 rather than the air bubble 151 from the shape of the photographed image.

[0069] In FIG. 6, an example in which the air bubble 151 is recognized as a square or a rectangle has been described. However, a large air bubble 151 can be recognized as having a shape approximated to a circle or an ellipse (a shape with rounded or rounded corners) rather than a square or a rectangle. Therefore, as the image processing shape of the air bubble 151, such shapes are also included. All such shapes are symmetric shapes and are different from the irregular shape having irregularities of the mineral 152. Therefore, even if there are some differences in the shape of the air bubble 151, as long as it does not fall below the recognition limit value, it can be recognized separately from the shape of the mineral 152.

[0070] Here, when recognizing the shape of the photographed image, it is not limited to the method described above. For example, it can also be performed by a method of recognizing the shape based on the circularity of the photographed image. Circularity is a numerical value evaluated by the ratio of the area of the recognized image to the perimeter of the recognized image in order to represent the complexity of the figure drawn in the image or the like. With the maximum value being 1, it decreases as the figure becomes more complex. Circularity can be obtained by the following calculation formula. Circularity = 4π × (area) ÷ (perimeter) 2 For example, in the case of a perfect circle with a radius of 10, the calculation formula is "4π × (10 × 10 × π) ÷ (10 × 2 × π) 2 ", and the circularity is 1. That is, in terms of circularity, a perfect circle is determined as the least complex figure. Similarly, the circularity of a square is 0.785, and the circularity of an equilateral triangle is approximately 0.604. The equilateral triangle is determined as a more complex figure than the square.

[0071] For an image of an irregular shape with irregularities like Mineral 152, the circularity is less than 0.785. Therefore, by setting the reference value of circularity to 0.785, it is possible to recognize an image with a circularity of 0.785 or more as a bubble in terms of shape recognition, while recognizing an image with a circularity less than 0.785 as a mineral in terms of shape recognition.

[0072] FIG. 8 is a diagram for explaining the discrimination threshold value of the digital camera. FIG. 8(a) is a diagram showing a state where Mineral 152 at the fine particle level is photographed, and FIG. 8(b) is a diagram showing a state where fine bubble 151 is photographed.

[0073] As shown in FIGS. 8(a) and 8(b), when Mineral 152 is fine, it is recognized in the shape of a 2×2 = 4-pixel square or rectangle, and image recognition is performed in the same square or rectangular shape as bubble 151 shown in FIG. 8(b). Therefore, with this digital camera, Mineral 152 cannot be recognized separately from bubble 151. That is, in the case of this digital camera, the length corresponding to 2 pixels becomes the discrimination threshold value for one side.

[0074] In addition, the same applies when performing shape recognition based on circularity. In a situation where Mineral 152 and bubble 151 are recognized in the same shape in an image, since there is no difference in the circularity between the two, Mineral 152 cannot be recognized separately from bubble 151 in terms of shape.

[0075] Thus, in imaging device 100, there is a discrimination threshold value unique to each device, and for Mineral 152 at the fine particle level smaller than the discrimination threshold value, it cannot be recognized separately from bubble 151.

[0076] Therefore, it is necessary to suppress the inflow of Mineral 152, which is a solid (fine particle) smaller than this discrimination threshold value, into measurement chamber 80.

[0077] However, it is impossible and unrealistic to completely suppress the inflow of fine particles. When the imaging device 100 captures the bubbles 151, it is sufficient that the inflow of fine particles is suppressed to such an extent that the bubbles 151 and the solid matter can be distinguished. Hereinafter, in order to include the solids other than the minerals 152 present in the ore slurry 150, the minerals 152 are comprehensively referred to as solid matter.

[0078] The introduction time of the bubbles 151 at which the inflow of fine particles can be suppressed to such an extent that the bubbles 151 and the solid matter can be distinguished is, for example, investigated in advance according to the shape of the introduction pipe 60, the properties of the liquid constituting the ore slurry 150, and the supply amount of the air supplied into the liquid to form the bubbles 151 (for example, investigated with a testing machine or the like). If the opening time of the bubble introduction valve 50 is adjusted to the introduction time found by this investigation to perform bubble measurement, the inflow of solid matter (fine particles) smaller than the discrimination limit value into the measurement chamber 80 can be suppressed. Thereby, highly accurate bubble measurement becomes possible.

[0079] The specific method for investigating the bubble introduction time is carried out as follows.

[0080] First, the bubble introduction valve 50 is opened for a predetermined time to collect the bubbles 151. At this time, turbidity will also be collected. Here, the opening time of the bubble introduction valve 50 is determined according to the shape of the introduction pipe 60, the properties of the ore slurry 150, and the supply amount of the air supplied into the ore slurry 150.

[0081] Regarding the shape of the introduction pipe 60, the length and the inner diameter size in the longitudinal direction of the introduction pipe 60 affect the opening time of the bubble introduction valve 50. That is, the longer the length of the introduction pipe 60, the more difficult it is for the fine particles of the solid matter contained in the ore slurry 150 to reach the measurement chamber 80. Therefore, the longer the length of the introduction pipe 60, the longer the opening time of the bubble introduction valve 50 can be set.

[0082] On the other hand, if the inner diameter of the introduction pipe 60 is large, the ore slurry 150 and the solids contained in the ore slurry 150 will easily pass through the introduction pipe 60, so it becomes necessary to set the opening time of the bubble introduction valve 50 to be short. Conversely, if the inner diameter of the introduction pipe 60 is set small, the ore slurry 150 and the solids contained in the ore slurry 150 will have difficulty passing through the introduction pipe 60, so it becomes possible to set the opening time of the bubble introduction valve 50 to be long.

[0083] Therefore, if the length of the introduction pipe 60 is set long and the inner diameter is set small, it becomes possible to set the opening time of the bubble introduction valve 50 to be long.

[0084] For example, when the inner diameter of the introduction pipe 60 is 50 mm or less, it has been confirmed that the opening time of the introduction opening valve 50 can be lengthened by setting the length of the introduction pipe 60 to 7 times or more the inner diameter. Specific numerical values will be described later. Note that the inner diameter of the introduction pipe 60 is preferably 5 mm or more. Thereby, it is possible to measure the largest 4 mm bubbles among the bubbles to be measured.

[0085] Regarding the properties of the ore slurry 150, the particle size of the ore contained in the ore slurry 150 and the slurry concentration affect the opening time of the bubble introduction valve 50. The ore particle size is determined by the indices of the maximum particle size and the average particle size. The maximum particle size is literally the maximum diameter of the ore particles contained in the ore slurry 150. The average particle size is the average diameter of the ore particles contained in the ore slurry 150, and is indicated by the median diameter (D50) at which the large side and the small side become equal when the particle size distribution of the ore particles is divided into two.

[0086] If the ore particle size is large, it becomes possible to set the opening time of the bubble introduction valve 50 to be long. However, in the case of an ore slurry 150 with a sufficiently large ore particle size, there may be a case where turbidity does not occur during bubble measurement in the first place, and there is no need to apply the present invention. It has been confirmed that the ore particle size for which an effect can be obtained by applying the present invention has a maximum particle size of 300 μm or less and an average particle size (median diameter D50) of less than 100 μm.

[0087] Also, regarding the slurry concentration, if the value is too large, the proportion of ore particles increases, and turbidity is likely to occur in the measurement chamber 80. Therefore, it is preferably below a predetermined value. For example, it has been confirmed that when the slurry concentration is set to less than 50 wt%, the opening time of the air introduction valve 50 can be set longer. When the slurry concentration is set to 50 wt% or more, the ore particles of the ore slurry 150 flow into the introduction pipe 60 and are likely to flow into the measurement chamber 80, making turbidity likely to occur. Therefore, it is preferable to adjust the slurry concentration to less than 50 wt%.

[0088] Regarding the amount of air supplied into the ore slurry 150, the smaller the supply amount, the longer the opening time of the air introduction valve 50 can be set. When the air supply amount increases, the bubbles 151 introduced from the air introduction valve 50 are likely to generate a flow, and it becomes easier to carry the ore particles into the introduction pipe 60. Therefore, from the perspective of setting the opening time of the air introduction valve 50 longer, it is preferable that the amount of air supplied to the ore slurry 150 is smaller.

[0089] Considering such parameters, the opening time of the air introduction valve 50 is adjusted. Among these parameters, the length of the introduction pipe 60 and the amount of air supplied to the ore slurry 150 are the elements that most affect the opening time of the air introduction valve 50.

[0090] In particular, when the introduction pipe 60 is set to have a length of a certain value or more, for example, 20 times or more the inner diameter of the introduction pipe 60, which is 500 mm or more when expressed as a numerical value, even when the amount of air supplied into the ore slurry 150 increases, the bubbles 151 and the solid matter can often be distinguished and recognized by image recognition.

[0091] It has been confirmed that the amount of air supplied into the ore slurry 150 is an element that has a large influence after the length of the introduction pipe 60, and this point will be described later.

[0092] In the investigation stage, while setting the above parameters, the opening time of the bubble introduction valve 50 is tentatively set accordingly. Then, with the set opening time, the bubble introduction valve 50 is opened to introduce the bubbles 151 into the introduction pipe 60. At this time, since the ore slurry 150 is also introduced into the introduction pipe, a certain degree of turbidity occurs.

[0093] Next, the ore slurry 150 containing turbidity in the measurement chamber 80 and the introduction pipe 60 is extracted, and the particle size distribution of the solid matter contained in the ore slurry 150 is determined.

[0094] If a peak in the particle size distribution of the solid matter contained in the ore slurry 150 is observed in a particle size range smaller than the discrimination threshold value of the imaging device 100, it is determined as NG. On the other hand, if no peak in the particle size distribution of the solid matter is observed in a particle size range smaller than the discrimination threshold value of the imaging device 100, it is determined as OK. Note that the discrimination threshold value of the imaging device 100 is grasped in advance.

[0095] If the determination is OK in the above determination, the opening time of the bubble introduction valve 50 set initially is adopted as the introduction time of the bubbles at which the inflow of fine particles can be suppressed to such an extent that the bubbles 151 and the solid matter can be discriminated.

[0096] Such an investigation is carried out while changing the above parameters, setting the opening times of the various bubble introduction valves 50, determining whether a peak in the particle size distribution of the solid matter contained in the ore slurry 150 is observed in a particle size range smaller than the discrimination threshold value of the imaging device, and adjusting the opening time of the bubble introduction valve 50.

[0097] At that time, while considering qualitative properties such as the longer the introduction pipe 60, the longer the opening time of the bubble introduction valve 50 can be set, and the less the supply amount of air into the ore slurry 150, the longer the opening time of the bubble introduction valve 50 can be set, the opening time of the bubble introduction valve 50 is set while making predictions, determined, and adjusted. And since these change when the properties of the ore slurry 150 change, they are set respectively corresponding to the properties of the ore slurry 150.

[0098] As a result, it is possible to set conditions for reliably measuring the bubbles 151 with respect to various ore slurries 150.

[0099] Thus, according to the bubble measurement apparatus and the bubble measurement method according to the present embodiment, corresponding to various ore slurries 150, an appropriate opening time of the bubble introduction valve 50 is set, the bubbles 151 are recognized separately from the solid matter, and bubble data such as bubble diameter and bubble number density can be accurately and reliably measured. In the above description, the introduction time of the bubbles 151 is investigated and set according to the shape of the introduction pipe 60, the properties of the liquid constituting the ore slurry 150, and the supply amount of the air supplied into the liquid to form the bubbles 151. However, the present invention is not limited to this. For example, other investigation items such as the distribution of the flow state (flow velocity distribution) of the slurry 150 can be further added to the investigation items and set.

[0100] [Examples] Next, an example in which the above-described bubble measurement method is implemented will be described. Also in the examples, the same reference numerals are given to the components corresponding to those in the first embodiment described above, and the description thereof is omitted.

[0101] FIG. 9 is a diagram showing the results of the examples and the comparative examples. In FIG. 9, as the shape of the introduction pipe, "length of the introduction pipe" and "diameter of the introduction pipe" are shown as parameter items. Further, "air supply amount" is listed as a parameter item, and "ore particle size of the slurry" and "slurry concentration" are shown as parameter items indicating the properties of the ore slurry. The discrimination limit value of the imaging device 100 is 30 μm.

[0102] In this example, with respect to the ore particle size in the ore slurry 150, an ore slurry 150 that satisfies the conditions that the maximum particle size is 300 μm or less and the median diameter (D50) is less than 100 μm was used. Further, an ore slurry 150 having a slurry concentration of less than 50 wt% was used.

[0103] Also, the size of the bubbles 151 was set so as to be 20 μm or more.

[0104] In Example 1 and Comparative Example 1, the length of the introduction pipe 60 was in the range of 200 mm or more and 500 mm or less, and the supply amount of air supplied to 1 L (liter) of the ore slurry 150 was in the range of more than 0.6 L / min and 4.0 L / min or less. The opening time of the bubble release valve 50 was variously set between several seconds and ten-odd seconds, and the bubbles 151 were introduced into the introduction pipe 60 at the set opening time. Then, the ore slurry 150 containing turbidity in the measurement chamber 80 and the introduction pipe 60 was extracted, and the particle size distribution of the solid matter contained in the ore slurry 150 was determined.

[0105] Note that the relationship between the length and the inner diameter of the introduction pipe 60 was set such that the length of the introduction pipe 60 was 7 times or more and less than 20 times the inner diameter.

[0106] In such a case, when the opening time of the bubble introduction valve 50 was 10 seconds or less, the peak of the particle size distribution became a value larger than 30 μm, and actually the bubbles 151 could also be identified without being affected by turbidity (Example 1).

[0107] On the other hand, when the opening time of the bubble introduction valve 50 exceeded 10 seconds, the peak of the particle size distribution became a value smaller than 30 μm, the bubbles 151 were also affected by turbidity, and it became difficult to distinguish and recognize the bubbles 151 from the turbidity (Comparative Example 1).

[0108] Also, in Example 2 and Comparative Example 2 of FIG. 9, the length of the introduction pipe 60 was in the range of 200 mm or more and 500 mm or less, and the supply amount of air supplied to 1 L of the ore slurry 150 was in the range of more than 0.2 L / min and 0.6 L / min or less. In this case, since the supply amount of air was made smaller than that in Example 1 and Comparative Example 1, the length of the bubble introduction valve 50 was set longer, the opening time of the bubble introduction valve 50 was set between about 35 seconds and about 45 seconds, and the bubbles 151 were introduced into the introduction pipe 60 at the set opening time. Then, the ore slurry 150 containing turbidity in the measurement chamber 80 and the introduction pipe 60 was extracted, and the particle size distribution of the solid matter contained in the ore slurry 150 was determined.

[0109] Then, when the opening time of the bubble introduction valve 50 is 40 seconds or less, the peak of the particle size distribution becomes a value greater than 30 μm, and actually the bubbles 151 could be identified without being affected by turbidity (Example 2).

[0110] On the other hand, when the opening time of the bubble introduction valve 50 exceeds 40 seconds, the peak of the particle size distribution becomes a value less than 30 μm, and the bubbles 151 are also affected by turbidity, making it difficult to distinguish and recognize the bubbles 151 from the turbidity (Comparative Example 2).

[0111] In Example 3 and Comparative Example 3, the length of the introduction pipe 60 was made 500 mm or longer, and the supply amount of air supplied to 1 L of the ore slurry 150 was in the range exceeding 0.6 L / min and 4.0 L / min or less, the same as in Example 1 and Comparative Example 1. Although the air supply amount was increased compared to Example 2 and the Comparative Example, since the length of the most influential introduction pipe 60 was set to 500 mm or longer and the length of the introduction pipe 60 was set to be 20 times or more the inner diameter, the opening time of the bubble introduction valve 50 was longer than 40 seconds and variously set in the range of 50 seconds or more.

[0112] As a result, when the opening time of the bubble introduction valve 50 was 60 seconds or less, the peak of the particle size distribution became a value greater than 30 μm, and actually the bubbles 151 could be identified without being affected by turbidity (Example 3).

[0113] On the other hand, when the opening time of the bubble introduction valve 50 exceeded 60 seconds, the peak of the particle size distribution became a value less than 30 μm, and the bubbles 151 were also affected by turbidity, making it difficult to distinguish and recognize the bubbles 151 from the turbidity (Comparative Example 3).

[0114] From these results, it was confirmed that as the influence of each element (parameter) on the turbidity in the measurement chamber 80, the influences of "the length of the introduction pipe" and "the air supply amount" were large.

[0115] Also, from the results of Examples 1 to 3 and Comparative Examples 1 to 3, it was advantageous for the introduction pipe 60 to be longer. The shorter the introduction pipe 60, the more likely it is to be affected by turbidity even if the opening time of the bubble introduction valve 50 is short. When the length of the introduction pipe 60 exceeds 500 mm or becomes 20 times or more the inner diameter of the introduction pipe 60, the turbidity gradually stops rising upward, and the influence of turbidity becomes negligible.

[0116] In this example, when the bubble diameter of the bubbles 151 is less than 20 μm, the floating speed is extremely slow (antagonistic to the speed at which turbidity rises), so the bubbles 151 having a size of 20 μm or more were targeted. The present invention can be suitably provided for at least an agitator type flotation machine and a Denver type flotation machine that generate such bubbles. However, the present invention can also be applied when the size of the bubbles 151 is less than 20 μm. For example, when the bubbles 151 are bubbles with an extremely slow floating speed less than 20 μm, the bubble introduction valve 50 can also be kept open at all times. Thus, the present invention is applicable not only to bubbles of 20 μm or more, but also to all bubbles with a bubble diameter of less than 20 μm.

[0117] Also, although the ore slurry 150 having an ore particle size with a maximum particle size of 300 μm or less and an average particle size D50 of less than 100 μm was targeted, the present invention is effective when used for the ore slurry 150 that satisfies this condition. The more fine particles there are, the easier it is to become turbid by riding on the flow. However, the present invention can also be applied to an ore slurry 150 with few fine particles. For example, when the ore slurry 150 is an ore slurry with few fine particles and no rising turbidity, the bubble introduction valve 50 can also be kept open at all times. Thus, the present invention is applicable not only to the ore slurry 150 with many fine particles, but also to all ore slurries including the ore slurry 150 with few fine particles.

[0118] In addition, the ore slurry concentration was set to less than 50 wt%. If it is 50 wt% or more, the turbidity flowing into the introduction pipe 60 will increase, and it is conceivable that the present invention may not be able to handle it. For example, when the ore slurry concentration is 50 wt% or more, it is necessary to set the opening time shorter than the opening time of the bubble introduction valve 50 set in FIG. 6.

[0119] Also, it was confirmed that a larger air supply amount is disadvantageous. As described above, this is because when air is introduced into the introduction pipe 60, it is easy to generate a flow.

[0120] In this way, considering the shape of the introduction pipe 60, the supply amount of air into the liquid, and the properties of the liquid, and accordingly setting the opening time of the bubble introduction valve 50 so that the bubbles 151 can be identified in the image taken by the imaging device 100, and adjusting so that the peak of the particle size distribution of the solid matter in the collected liquid does not fall below the identification limit value of the imaging device 100, the bubbles 151 can be surely measured.

[0121] Note that for the measurement of the bubbles 151, various data measurements can be performed according to the application, such as the number density of the bubbles 151 in addition to the bubble diameter.

[0122] FIG. 10 is a diagram showing an image of bubbles measured by the bubble measurement method using the bubble measurement device according to the present embodiment. As described above, according to the bubble measurement method and the bubble measurement device according to the present embodiment, the bubbles are not mixed with the fine particles, and the bubbles can be surely and accurately measured.

[0123] [Second Embodiment] (Basic Configuration of Bubble Diameter Measuring Device and Flotation Machine) FIG. 11 is a schematic diagram showing the configuration of a bubble measuring device according to a second embodiment of the present invention and a flotation machine to which the bubble measuring device is applied. The bubble measuring device according to the second embodiment of the present invention includes a bubble introduction valve 50, an introduction pipe 60, a frame 70, a measurement chamber 80, a light projecting device 90, a photographing device 100, a first on-off valve 110, a second on-off valve 320, and a branch pipe 130. Further, if necessary, an observation solution introduction pipe 340, a pump 350, an observation solution storage tank 360, an observation solution supply source 170, an observation solution discharge pipe 180, a waste liquid tank 190, a discharge pump 200, a drainage facility 210, a compressed air source 220, electromagnetic on-off valves 230, 231, 232, and a control device 240 may be provided. Note that the same reference numerals may be assigned to the same components as those in the first embodiment.

[0124] Further, the flotation machine 40 to which the bubble measuring device according to the present embodiment is applied includes a flotation cell 10, an air supply shaft 20, and an agitation blade 30. Further, as related components of the flotation machine 40 and the bubble measuring device, a liquid 250 containing solid particles is stored in the flotation cell 10.

[0125] As the flotation machine 40 according to the present embodiment, various generally used flotation machines can be used. For example, an agitator type flotation machine or a Denver type flotation machine may be used.

[0126] The flotation cell 10 is a liquid storage means for storing a liquid 250 containing a pulverized material to be beneficiated. The liquid 250 contains, for example, ore. Air is supplied into the liquid 250, and by causing the air to become bubbles and adhere to the ore, flotation beneficiation is performed to collect useful metals.

[0127] The air supply shaft 20 is an air supply means for supplying air (air) from the lower end. As described above, by supplying air into the liquid 250, bubbles for adhering the ore are generated. For example, the lower end of the air supply shaft 20 is disposed near the bottom surface of the flotation cell 10, and bubbles are generated from near the bottom surface of the flotation cell 10.

[0128] The stirring blade 30 is a bubble refinement means for making the bubbles generated by the air supplied from the lower end of the air supply shaft 20 finer. The bubbles generated at the lower end of the air supply shaft 20, that is, at the central part of the stirring blade 30, when discharged from the stirring blade 30, collide with the stirring blade 30 due to the rotation of the stirring blade 30, whereby the bubble diameter becomes smaller.

[0129] Since the diameter, number density, etc. of the bubbles affect the flotation performance, it is important to measure and manage the bubbles in order to improve the flotation performance. The bubble measuring device according to the present embodiment is used to measure the bubble diameter, bubble density, etc.

[0130] In the present embodiment, the basic configuration of the bubble measuring device, as its device configuration, includes a measurement chamber 80 to be described later. Above the measurement chamber 80, a first on-off valve 110 for opening and closing the flow of the observation solution 260 to the measurement chamber 80 is provided. Below the measurement chamber 80, a second on-off valve 320 having the same function as the upper first on-off valve 110 is provided. Further, below the measurement chamber 80, an introduction pipe 60 for introducing bubbles and a bubble introduction valve 50 for introducing and blocking the bubbles inside the introduction pipe 60 are provided.

[0131] The bubble diameter measuring device preferably includes, as its basic configuration, a photographing device 100 capable of visually recognizing the state of the bubbles in the measurement unit 83a in the measurement chamber 80 and a light projecting device 90. The details of the light projecting device 90 and the photographing device 100 will be described later.

[0132] In addition, a pump 350 is connected to the first on-off valve 110 via an observation solution introduction pipe 340. An observation solution storage tank 360 is connected to the primary side of the liquid feed pump 350, and the pump 350 is configured to be able to feed the observation solution 260 in the observation solution storage tank to the first on-off valve 110. Note that the observation solution storage tank 360 is configured to be able to be supplied with the observation solution 260 from an observation solution supply source 170. Further, near the lower end of the introduction pipe 60, a branch pipe 330 is provided, and a second on-off valve 320 is connected to the introduction pipe 60. A discharge pipe 180 is connected to the second on-off valve 320, and a waste liquid tank 190 is provided at the tip of the discharge pipe 180, and the waste liquid tank 190 is configured to be able to receive the discharged liquid from the second on-off valve 320. Further, a discharge pump 200 is connected to the waste liquid tank 190, and the waste water stored in the waste liquid tank 190 is configured to be able to be discharged to a drainage facility 210.

[0133] Furthermore, if necessary, when the first on-off valve 110, the second on-off valve 320, and the bubble introduction valve 50 are, for example, air-driven, a control device 240 for opening and closing driving an air source 220, on-off solenoid valves 230, 231, 232 is provided as necessary. The on-off solenoid valve 230 is a driving means for opening and closing the bubble introduction valve 50, and the on-off solenoid valve 231 is a driving means for opening and closing the first on-off valve 110. Also, the on-off solenoid valve 232 is a driving means for opening and closing the second on-off valve 320.

[0134] Specifically, the measurement of bubbles is performed as follows.

[0135] First, bubbles rising from the bubble introduction valve 50 are introduced. The introduced bubbles are introduced into the measurement chamber 80 via the introduction pipe 60. Light is irradiated from the light projection device 90 onto the measurement chamber 80, and the imaging device 100 captures the bubbles in the measurement chamber 80, obtains necessary information such as the bubble diameter and the number density of bubbles from the captured image, and measures those values. In bubble measurement, the measurement chamber 80 is initially filled with a transparent observation solution 260. However, since the ore slurry is also introduced during the introduction of bubbles, the inside of the measurement chamber 80 becomes turbid. If the degree of turbidity is large, it becomes difficult to distinguish between bubbles and ore (solids), and accurate measurement of bubbles becomes difficult.

[0136] When such a state occurs, in order to continue the measurement of bubbles, it is necessary to replace the observation solution 260 filled in the measurement chamber 80 to make it a transparent state where bubbles can be observed. Conventionally, in such a case, the bubble measurement device is lifted, the turbid observation solution 260 is discharged from the bubble introduction valve 50 or the first on-off valve 110, and a new observation solution 260 is introduced into the measurement chamber 80 from the first open valve 110, and then the bubble measurement device is reinstalled in the flotation machine 40 to resume bubble measurement. This is a very time-consuming and labor-intensive operation.

[0137] In the bubble measurement device and the bubble measurement method according to this embodiment, a second on-off valve 320 is provided to form a path through which the observation solution 260 can flow above and below the measurement chamber 80, enabling the replacement of the observation solution 260 without lifting the bubble measurement device from the flotation machine 40.

[0138] The bubble size measuring device according to this embodiment closes the first on-off valve 110 and the second on-off valve 320 during the actual photographing of bubbles, and opens the bubble introduction valve 50 to introduce bubbles into the introduction pipe 60 for photographing the bubbles. On the other hand, before performing such photographing, the bubble size measuring device according to this embodiment closes the bubble introduction valve 50 and opens both the first on-off valve 110 and the second on-off valve 320 to supply the transparent observation solution 260 into the measurement chamber 80 from the side of the first on-off valve 110 or from the side of the second on-off valve 320. At the same time, the observation solution 260 that filled the measurement chamber 80 before the supply of such observation solution 260 is discharged and replaced from the on-off valve on the side different from the supply side. Thereby, the transparency of the observation solution 260 filling the measurement chamber 80 is ensured. That is, whether the liquid containing the bubbles to be measured is a liquid without solid particles such as fresh water or seawater, or a liquid containing solid particles, clear photographing is possible. Also, even when it is a liquid containing minute bubbles, the bubbles adhering to the inside of the bubble size measuring device before photographing can be washed away, so that the size and quantity of the generated bubbles can be appropriately grasped.

[0139] Furthermore, since the bubble size measuring device according to this embodiment can replace the observation solution 260 in the measurement chamber 80 only by opening and closing the first and second on-off valves 110 and 320, every time the observation solution 260 in the measurement chamber 80 is replaced, it is not necessary to lift the bubble size measuring device from the flotation tank 10 in which the liquid 250 containing the bubbles to be measured is stored, and the above-described photographing can be efficiently performed.

[0140] Hereinafter, the details of the components of the bubble measuring device according to this embodiment will be described.

[0141] (Measurement Chamber) Referring to FIG. 2 again. FIG. 2 is an enlarged view of the measurement chamber 80. FIG. 2(a) is a side view of the measurement chamber 80, and FIG. 2(b) is a front view of the measurement chamber 80.

[0142] In the present embodiment, the measurement chamber 80 is composed of a plurality of transparent members. In this embodiment, the material of these members is vinyl chloride. As the material of the members, members with a high light transmittance can be preferably used so that the light projected from the light projecting device 90 can pass through the measurement chamber 80 and be measured by the imaging device 100. The light transmittance of the members is preferably 80% or more, more preferably 90% or more, in the visible light region of wavelengths from 400 nm to 700 mm.

[0143] In addition to vinyl chloride, glass, acrylic, polyethylene terephthalate (PET), polycarbonate, etc. can be used as the members that satisfy the above-described optical characteristics.

[0144] Vinyl chloride can be preferably used as a member of the measurement chamber 80 because it is inexpensive, has high workability, and high transparency. In addition, acrylic has higher transparency than vinyl chloride, is less likely to be scratched, and has less reduction in transparency, so it can be preferably used for installation in places where replacement is difficult.

[0145] The measurement chamber 80 is provided with a main member 82, a first lid member 83, and a second lid member 84 so as to sandwich the main member 82. The outer shape of the main member 82 is a thick rectangular plate shape, that is, a flat quadrangular prism shape. The main member 82 is provided with a measurement hole 82a having a relatively large diameter. The axial direction of this measurement hole 82a coincides with the thickness direction of the thinnest thickness of the quadrangular prism form of the main member 82 (hereinafter this direction may be referred to as the thickness direction of the main member 82). By sandwiching the main member 82 between the first lid member 83 and the second lid member 84 so as to close the measurement hole 82a, the portion of the measurement hole 82a becomes a space closed in the axial direction of the measurement hole 82a.

[0146] Here, among the spaces formed by the main member 82, the first lid member 83, and the second lid member 84, the right side surface of the first lid member 83 is referred to as a transparent inclined surface, and among this transparent inclined surface, the portion where the measurement hole 82a is located is referred to as a measurement portion 83a.

[0147] The measurement chamber 80 further includes an introduction pipe connection member 81 provided below the main member 82 and a lead-out pipe 85 provided above the main member 82. The introduction pipe 60 is connected via the introduction pipe connection member 81. Here, since the introduction pipe connection member 81 has a through hole and both the introduction pipe 60 and the lead-out pipe 85 have a cylindrical structure, the measurement chamber 80 has a vertically communicating structure through these members. By being communicated in this way, it is possible to hold the liquid 250 in the measurement chamber 80 and to introduce the bubbles in the liquid 250 from the introduction pipe 60.

[0148] The introduction pipe 60 connected to the introduction pipe connection member 81 is arranged such that the axis of the inner surface of the pipe is in the vertical direction. Also, the upper surface of the introduction pipe connection member 81 connected to the introduction pipe 60 is inclined by an inclination angle θ from the horizontal plane. Due to the inclination of the upper surface of the introduction pipe connection member 81 in this way, the transparent inclined surface including the measurement part 83a is inclined by the inclination angle θ from the vertical. That is, the normal line of the transparent inclined surface is downward, and the transparent inclined surface is in a posture facing obliquely downward. The inclination angle θ is determined such that the transparent inclined surface is located at the position where the bubbles rising from the introduction port come. In this embodiment, the inclination angle θ is 15 degrees, but it may be set to various angles according to the application. By inclining the measurement part 83a, it is possible to photograph the bubbles with all the bubbles in focus.

[0149] Due to the transparent inclined surface being inclined by the inclination angle θ, the bubbles rising in the liquid come into contact with the transparent inclined surface including the measurement part 83a. In the case of bubbles having a size equal to or larger than a certain size, the bubbles rise along this transparent inclined surface. By the bubbles rising in this way, it is possible to prevent the bubbles from overlapping, so that the size and quantity of the bubbles can be accurately measured. At this time, there is almost no movement of the liquid containing the bubbles.

[0150] The diameter L1 of the measurement hole 82a of the main member 82 constituting the bubble measurement device of this embodiment is longer than the diameter of the inner surface of the introduction pipe 60. Here, the diameter L1 of the measurement hole 82a is the length in the left-right direction of the measurement part 83a when the transparent inclined surface is viewed from the front.

[0151] In addition, the main member 82 is provided with the measurement hole 82a as described above, and an enlarged communication portion for communicating the measurement hole 82a with the introduction pipe 60 is provided. The enlarged communication portion has a groove shape. The length in the left-right direction up to the measurement portion 83a of the groove portion of the enlarged communication portion increases at a constant ratio from the lower side to the upper side. The depth of the groove shape of the enlarged communication portion has a depth of 1 / 3 of the length in the thickness direction of the main member 82.

[0152] (Light projection device and imaging device) The light projection device 90 irradiates the measurement portion 83a with light of a predetermined type from one surface of the measurement chamber 80. Thereby, imaging inside the measurement chamber 80 becomes easy. As the illumination means, for example, surface illumination such as a white LED is preferably used.

[0153] The imaging device 100 is preferably a digital camera or the like that can image at least one of a still image and a moving image. The size and quantity of the bubbles imaged by this imaging device 100 are preferably analyzed by software that performs image processing. The imaging device 100 may use various imaging devices as long as it can appropriately image the bubbles. For example, the imaging device 100 may use a device with a shooting speed of 3.3 fps and capable of continuous shooting.

[0154] (Frame) The frame 70 is a support member for supporting the measurement chamber 80, the light projection device 90, and the imaging device 100.

[0155] (Introduction pipe) In the present embodiment, the introduction pipe 60 is a pipe material having a cylindrical cross-section with both ends open, and is longitudinally divided, and a branch pipe 330 is inserted into the divided portion. Here, the branch pipe 330 is a pipe material having a branch shape with at least a pair of opposing connection end pairs. One of the introduction pipes 61 obtained by dividing the introduction pipe 60 is connected to one end of the opposing connection pair, and the other divided introduction pipe 62 is connected to the other end of the connection pair. A bubble introduction valve 50 is attached to the end of the introduction pipe 61 on the side immersed in the liquid 250, and an introduction pipe connection member 81 is attached to the end of the introduction pipe 62 on the measurement chamber 80 side.

[0156] The introduction pipe 60 can be divided at any location, and the above-described branch pipe 330 is inserted into the divided location, and the introduction pipe 61 and the introduction pipe 62 obtained by dividing the introduction pipe 60 can be respectively attached to the connection end pairs 331 and 332.

[0157] The branch pipe 330 has at least a pair of opposing connection end pairs 331 and 332 and a connection end 333 different from the pair of connection end pairs 331 and 332, and when the divided introduction pipes 61 and 62 are respectively attached to the connection end pairs 331 and 332, it forms a flow path that penetrates straight from one introduction pipe 61 to the other introduction pipe 62. Examples of the branch pipe 330 that satisfies such conditions include a T-shaped pipe. Thereby, since a flow path that penetrates from one introduction pipe 61 to the other introduction pipe 62 can be formed, the bubbles introduced into the introduction pipe 60 can be directly delivered into the measurement chamber 80 without being retained in the introduction pipe 60 or the branch pipe 330.

[0158] Note that the attachment of the branch pipe 330 to the introduction pipe 60 does not assume that the introduction pipe 60 is divided. For example, the introduction pipe 61 can be attached to one of the connection end pairs 331 without division, and a bubble introduction valve 50 or an introduction pipe connection member 81 can be attached to the other. In this case, if necessary, as a connecting member, for example, a pipe material having the same function as the introduction pipe 61 may be provided between the branch pipe 330 and the bubble introduction valve 50 or the introduction pipe connection member 81.

[0159] Further, in the present embodiment, a second on-off valve 320 is attached to a connection end 333 different from the pair of connection end pairs 331 and 332 of the branch pipe 330. In this case, a connecting member may be provided between the connection end 333 and the second on-off valve 320 described above.

[0160] As described above, by opening and closing the second on-off valve 320 attached via the branch pipe 330 together with the opening and closing of the first on-off valve 110, the supply, discharge, and interruption of the observation solution 260 into the introduction pipe 60 can be freely performed.

[0161] The insertion position of the branch pipe 330 with respect to the introduction pipe 60 is preferably adjusted to be as close as possible to the bubble introduction valve 50. Thereby, the transparent observation solution 260 is supplied into the measurement chamber 80 from the side of the first on-off valve 110 or from the side of the second on-off valve 320, and the observation solution 260 that fills the measurement chamber 80 before the re-supply of the observation solution 260 is discharged from the on-off valves 110 and 320 different from the supplied side. Most of the observation solution 260 in the introduction pipe 60 can be discharged together with the observation solution 260 in the measurement chamber 80, which is more advantageous for ensuring the transparency of the observation solution 260.

[0162] The length of the introduction pipe 60 is not particularly limited, but is preferably at least twice or more the inner diameter of the introduction pipe 60. If it is less than twice, when the liquid to be immersed contains solid particles, the solid particles introduced together with the bubbles through the bubble introduction valve 50 are likely to reach the inside of the measurement chamber 80, and there is a risk that clear imaging cannot be performed.

[0163] (Bubble introduction valve) In the present embodiment, the bubble introduction valve 50 is a valve body that can switch between a state in which the liquid 250 containing solid particles can move and a state in which the movement of the liquid 250 is blocked, and can be attached to the end of the introduction pipe 60 or to the branch pipe 330 (when the introduction pipe 60 is not divided), and is a part immersed in the liquid 250 containing bubbles to be measured.

[0164] Furthermore, the bubble introduction valve 50 is preferably a valve body through which the flow path passes when the valve is opened. This can effectively prevent bubbles from staying inside the valve body. Examples of valves that meet such requirements include mechanical valves such as ball valves, gate valves, and butterfly valves, as well as air expansion valves that have an elastic deformation member inside.

[0165] (First on-off valve) In the present embodiment, the first on-off valve 110 is a valve body provided above the measurement chamber 80 and is attached to the lead-out pipe 85 of the measurement chamber 80. In this case, a connecting member may be provided between the lead-out pipe 85 and the first on-off valve 110. By opening and closing the first on-off valve 110 and simultaneously opening and closing the second on-off valve 320, it is possible to supply, discharge, or block the observation solution 260 into the introduction pipe 60. Also, the first on-off valve 110 only needs to be a valve body that can switch between a state where the observation solution 260 containing solid particles flowing in from the liquid 250 can move and a state where the movement of the observation solution 260 containing these solid particles is blocked, and it does not need to be a valve body through which the flow path passes straight when the valve is opened. Therefore, valves such as globe valves can be widely adopted. Furthermore, if the valve body is such that the flow path passes through when the valve is opened, it is preferable because it facilitates cleaning inside the valve body when discharging the observation solution 260.

[0166] Here, the first on-off valve 110 preferably has a structure capable of connecting pipe materials on a side different from the side where the lead-out pipe 85 is attached. Thereby, when supplying the transparent observation solution 260 into the measurement chamber 80 from the first on-off valve 110 side, a pump 350 (hereinafter also referred to as "transparent liquid pump 350") for sending the transparent observation solution 260 through this pipe material can be attached. On the other hand, when discharging the observation solution 260 in the measurement chamber 80 from the first on-off valve 110 side, a waste liquid tank 190 for receiving the discharged observation solution 260 can be provided on the downstream side of this pipe material.

[0167] (Second on-off valve) In the present embodiment, the second on-off valve 320 is a valve body provided below the measurement chamber 80 and is attached to a branch pipe 330 inserted into the introduction pipe 60. Here, the second on-off valve 320 is a valve body having the same structure as the first on-off valve 110, and preferably has a structure capable of connecting pipe materials on a side different from the side to which the branch pipe 330 is attached. Thereby, when supplying the transparent observation solution 260 into the measurement chamber 80 from the second on-off valve 320 side, a transparent liquid pump 350 for feeding the transparent observation solution 260 through this pipe material can be attached. On the other hand, when discharging the observation solution 260 in the measurement chamber 80 from the second on-off valve 320 side, a waste liquid tank 190 for receiving the discharged observation solution 260 can be provided on the downstream side of this pipe material.

[0168] In FIG. 11, a configuration is shown in which a new observation solution 260 is introduced into the measurement chamber 80 from the first on-off valve 110 and the used observation solution 260 is discharged from the second on-off valve 320. However, if the pipe 340 is connected to the second on-off valve 320 and the pipe 180 is connected to the first on-off valve 110, a configuration can be adopted in which the transparent observation solution 260 is introduced into the measurement chamber 80 from the second on-off valve 320 and the used turbid observation solution 260 is discharged from the first on-off valve 110 to the waste liquid tank 190.

[0169] (Opening and closing operations of the bubble introduction valve, the first on-off valve, and the second on-off valve) In this embodiment, the opening and closing operations of the bubble introduction valve 50, the first on-off valve 110, and the second on-off valve 320 are performed via a power device. However, the opening and closing operations of the bubble introduction valve 50, the first on-off valve 110, and the second on-off valve 320 are not limited to being via a power device, and they can also be manually operated. Examples of adoptable power devices include on-off solenoid valves 230, 231, and 232 using compressed air as a power source. In the bubble introduction valve 50, a ball valve, a gate valve, or a butterfly valve may be combined with the on-off solenoid valve 230. In the first on-off valve 110 and the second on-off valve 320, a globe valve may be combined with the on-off solenoid valves 231 and 232. Furthermore, the on-off solenoid valves 230 to 232 may be controlled via a control device 240. If a programmable logic controller (hereinafter also referred to as "PLC" (Programable Logic Controller)) is used as the control device 240, it becomes easy to make the opening and closing operations of each valve 50, 110, and 320 cooperate with the operation of the imaging device 100 and the operation of the transparent liquid pump 350. Furthermore, by configuring it as a series of operations including the supply, discharge, and shut-off of the observation solution 260 into the measurement chamber 80, the introduction and shut-off into the bubble introduction pipe 60, and the operation and stop of the imaging device 100, continuous measurement becomes possible, and more efficient imaging can be performed, which is preferable.

[0170] The air source 220 is a drive source when driving the bubble introduction valve 50, the first on-off valve 110, and the second on-off valve 320 by air. When the on-off solenoid valve 230 is opened, air is supplied from the air source 220 to the bubble introduction valve 50, and the bubble introduction valve 50 performs an opening or closing operation. Similarly, when the on-off solenoid valves 231 and 232 are opened, air is supplied from the air source 220 to the first and second on-off valves 110 and 320, and the first and second on-off valves 110 and 320 perform an opening or closing operation. The air source 220 may be a compressed air supply source that supplies compressed air.

[0171] (Control system of the bubble measurement device) In this embodiment, the control system of the bubble measurement device includes a control device 240 composed of a microcomputer system (for example, a PLC). An operation control program of the bubble measurement device is pre-installed in the control device 240, and the supply, discharge, and cutoff of the observation solution 260 into the measurement chamber 80, the introduction and cutoff of bubbles into the introduction pipe 60 of the bubbles, and the operation and stop of the imaging device 100 are controlled as a series of operations.

[0172] Connected to the control device 240 are a solenoid valve 230 for opening and closing the bubble introduction valve 50, a solenoid valve 231 for opening and closing the first on-off valve 110, and a solenoid valve 232 for opening and closing the second on-off valve 320. Further, the control device 240 is connected to an imaging end detection sensor 101 provided in the imaging device 100 for detecting the end of imaging. Here, as the imaging end detection sensor 101, for example, an operation detection type sensor can be used. In this case, when the passage of bubbles through the measurement unit 83a is completed, it is detected as the time point when imaging is completed. Alternatively, as a simpler one, a timer can be used. In this case, when a predetermined time has elapsed since the imaging device 100 started operating, it is detected as the time point when imaging is completed. Furthermore, the control device 240 is connected to the imaging device 100, the imaging end detection sensor 101, and a transparent liquid pump 350.

[0173] In this embodiment, a transparent liquid pump 350 for supplying a transparent observation solution 260 into the measurement chamber 80 is provided on the side of the first on-off valve 110, and a waste liquid tank 190 for receiving the observation solution 260 discharged from the measurement chamber 80 is provided on the side of the second on-off valve 320.

[0174] For the control system of the bubble measurement device configured as described above, for example, the following control can be performed.

[0175] FIG. 12 is a diagram showing an example of a control flow of the bubble measurement device and the bubble measurement method according to this embodiment.

[0176] 1) In FIG. 12, in step S1, the on-off solenoid valve 230 of the bubble introduction valve 50 is operated to close the bubble introduction valve 50, and the on-off solenoid valve 231 of the first on-off valve 110 and the on-off solenoid valve 232 of the second on-off valve 320 are operated to open both the first on-off valve 110 and the second on-off valve 320. Also, the transparent liquid pump 350 is operated to supply the transparent observation solution 260 into the measurement chamber 80 and discharge the used observation solution 260 from the measurement chamber 80.

[0177] 2) In step S2, after a predetermined time has elapsed, the on-off solenoid valve 231 of the first on-off valve 110 and the on-off solenoid valve 232 of the second on-off valve 320 are operated to close both the first on-off valve 110 and the second on-off valve 320. As a result, the measurement chamber 80 is filled with the transparent observation solution 260.

[0178] 3) In step S3, the on-off solenoid valve 230 of the bubble introduction valve 50 is operated to open the bubble introduction valve 50, and the imaging device 100 is operated to start imaging.

[0179] 4) In step S4, after a predetermined time has elapsed, the on-off solenoid valve 230 of the bubble introduction valve 50 is operated to close the bubble introduction valve 50 and cut off the introduction of bubbles into the introduction pipe 60.

[0180] 5) In step S5, on the condition that the imaging end detection sensor 101 detects that the last bubble has passed through the measurement unit 83a, the imaging device 100 is stopped to end the imaging. When the imaging is completed, the liquid 250 containing solid particles is introduced into the observation solution 260, and turbidity occurs in the introduction pipe 60. 6) In step S6, if the measurement is completed in one go, the processing flow ends. On the other hand, if the measurement is not completed, it returns to step S1, and upon completion of the imaging, the on-off solenoid valve 231 of the first on-off valve 110 and the on-off solenoid valve 232 of the second on-off valve 320 are operated to open both the first on-off valve 110 and the second on-off valve 320, and the transparent liquid pump 350 is operated to supply the transparent observation solution 260 into the measurement chamber 80, and the observation solution 260 is discharged from the measurement chamber 80 and the introduction pipe 60.

[0181] 7) Again in step S2, after a predetermined time has elapsed, the on-off solenoid valve 231 of the first on-off valve 110 and the on-off solenoid valve 232 of the second on-off valve 320 are operated to close both the first on-off valve 110 and the second on-off valve 320.

[0182] 8) Thereafter, if steps S3 to S6 are executed and the measurement of bubbles is to be continued, steps S1 to S6 are repeated. When the overall measurement is completed, the processing flow ends and the bubble measuring device is lifted from the flotation machine 40. Note that if the degree of turbidity in the measurement chamber 80 is small and the discrimination between bubbles and ore (solid matter) is possible, it is not necessarily required to return all the way to S1, and steps S3 to S6 may be repeated. Thereby, the measurement interval can be shortened and the measurement can be continued efficiently.

[0183] In the bubble measuring device configured as described above, when the liquid containing the bubbles to be measured is a liquid that does not contain solid particles such as fresh water or seawater, or when it is the liquid 250 containing solid particles, clear imaging can be performed. Also, when it is the liquid 250 containing minute bubbles, the bubbles adhering inside the bubble measuring device before imaging can be washed away. Therefore, it is possible to appropriately measure and grasp the size and quantity of the generated bubbles.

[0184] In addition, since the observation solution 260 in the measurement chamber 80 can be replaced only by the opening and closing operation of the valve, it is not necessary to lift the bubble measuring device from the flotation cell 10 storing the liquid 250 containing the bubbles to be measured each time the observation solution 260 in the measurement chamber 80 is replaced.

[0185] Furthermore, since it is configured as a series of operations including the supply, discharge, and cutoff of the observation solution 260 to and from the measurement chamber 80, the introduction and cutoff of bubbles to and from the introduction pipe 60, and the operation and stop of the imaging device 100, continuous measurement becomes possible, and more efficient imaging can be performed.

[0186] (Method of using the bubble size measuring device) First, the user of the bubble size measuring device determines the posture of the bubble size measuring device so that the transparent inclined surface of the measurement chamber 80 of the bubble size measuring device has a predetermined inclination angle θ, that is, so that the axis of the introduction pipe 60 is vertical (see Fig. 2). Then, the light projecting device 90 and the imaging device 100 are prepared so that the measurement unit 83a of the measurement chamber 80 can perform measurement. Then, the bubble introduction valve 50 is immersed in the container storing the liquid 250 containing the bubbles to be measured. For example, the user immerses the bubble introduction valve 50 at a predetermined position in the flotation cell 10 of the flotation separator. In the present embodiment, a transparent liquid pump 350 for supplying the transparent observation solution 260 into the measurement chamber 80 is provided on the side of the first on-off valve 110, and a waste liquid tank 190 for receiving the observation solution 260 discharged from the measurement chamber 80 is provided on the side of the second on-off valve 320.

[0187] Next, the user of the bubble measuring device closes the bubble introduction valve 50, opens both the first on-off valve 110 and the second on-off valve 320, and operates the transparent liquid pump 350 to supply the transparent observation solution 260 into the measurement chamber 80 and discharge the observation solution 260 from the measurement chamber 80 to the waste liquid tank 190. After a predetermined time has elapsed, the transparent liquid pump 350 is stopped, and the first on-off valve 110 and the second on-off valve 320 are closed. As a result, the measurement chamber 80 and the introduction pipe 60 are filled with the transparent observation solution 260.

[0188] Next, open the bubble introduction valve 50 to introduce bubbles into the introduction pipe 60. At the same time, operate the imaging device 100 to start imaging. After a predetermined time has elapsed since opening the bubble introduction valve 50, close the bubble introduction valve 50. At this point, the imaging continues. After a further predetermined time has elapsed since closing the bubble introduction valve 50, the last bubble passes through the measurement unit 83a in the measurement chamber 80, and at this point, stop the imaging device 100 to end the imaging.

[0189] Next, open both the first on-off valve 110 and the second on-off valve 320, and operate the transparent liquid pump 350 to supply the transparent observation solution 260 into the measurement chamber 80, and discharge the used observation solution 260 from the measurement chamber 80 toward the waste liquid tank 190.

[0190] By repeating this operation, it is possible to continuously measure bubbles.

[0191] Note that such an operation is the same as the control flow described in FIG. 12, but the opening and closing of the valves, the end of imaging, etc. can also be performed manually without using the control device 240. In this case, the opening and closing of the valves are performed manually, and the end of imaging may be stopped after a predetermined time has elapsed.

[0192] As described above, the bubble measuring device and the bubble measuring method according to the present embodiment can be configured and implemented even without the control device 240 and the electromagnetic on-off valves 230 to 232.

[0193] Also, in FIG. 11, if the pipe 340 is connected to the second on-off valve 320 and the pipe 180 is connected to the first on-off valve 110, it has already been described that the transparent observation solution 260 can be introduced from the second on-off valve 320 and the used observation solution 260 can be discharged from the first on-off valve 110, but it may be configured to be switchable between both using a switching valve or the like. For example, in FIG. 11, by providing a branch pipe connected from the pipe 340 to the second on-off valve 320 and a branch pipe connected from the pipe 180 to the first on-off valve 110, and providing a three-way valve at the branch point, a configuration that allows such up-down switching can be achieved.

[0194] Thus, according to the bubble measuring apparatus and the bubble measuring method according to this embodiment, by filling the inside of the measurement chamber 80 with the transparent observation solution 260 and replacing the observation solution 260 with the transparent observation solution 260 by operating the on-off valve when it becomes turbid, a good measurement state can be ensured.

[0195] Although the embodiment in which the observation solution 260 is replaced to keep the measurement state inside the measurement chamber 80 good has been described, it is also possible to further implement a device for suppressing turbidity inside the measurement chamber 80 and distinguishing and recognizing bubbles without being confused with solid particles.

[0196] Hereinafter, this content will be described.

[0197] First, in distinguishing between bubbles and solids, there is a size (discrimination limit value) that serves as the discrimination limit according to the resolution of the imaging device 100 used. The discrimination limit value will be described below.

[0198] FIG. 13 is a diagram for explaining the resolution of a digital camera, and shows a state in which a bubble 251 is photographed. As shown in FIG. 13, the bubble 251 often has a shape approximated to a circle or an ellipse, and 4×4 = 16 pixels are required to recognize the bubble 251. If these 16 pixels are recognized with binary 1 or 0 and photographed, these 16 pixels become 1, and the surroundings become 0, and the bubble 251 is recognized as a rectangle as an image. That is, when the rectangular shape can be recognized, it can be determined that the bubble 251 has been imaged.

[0199] FIG. 14 is a diagram showing a state in which the solid matter 252 is photographed with a digital camera. As shown in FIG. 14, the solid matter 252 has an irregular shape with unevenness, and the corresponding pixel (region recognized as 1) also has an irregular shape with unevenness. As described above, in the case of the air bubble 251, it is recognized as having a square or rectangular shape, but since the solid matter 252 is recognized as having an irregular shape with unevenness, it is possible to distinguish and recognize that it is the solid matter 252 rather than the air bubble 251 from the shape of the photographed image.

[0200] In FIG. 13, an example in which the air bubble 251 is recognized as a square or a rectangle has been described. However, a large air bubble 251 can be recognized as having a shape approximated to a circle or an ellipse (a shape with rounded or rounded corners) rather than a square or a rectangle. Therefore, the image processing shape of the air bubble 251 also includes such a shape. All such shapes are symmetric shapes and are different from the irregular shape with unevenness of the solid matter 252. Therefore, even if there are some differences in the shape of the air bubble 251, as long as it does not fall below the recognition limit value, it can be distinguished and recognized from the shape of the solid matter 252.

[0201] Here, when recognizing the shape of the photographed image, it is not limited to the method described above. For example, it can also be performed by a method of recognizing the shape according to the circularity of the photographed image. Circularity is a numerical value evaluated by the ratio of the area of the recognized image and the perimeter of the recognized image for representing the complexity of the figure drawn in the image or the like. With the maximum value being 1, it decreases as the figure becomes more complex. Circularity can be obtained by the following calculation formula. Circularity = 4π × (area) ÷ (perimeter) 2 For example, in the case of a perfect circle with a radius of 10, the calculation formula is "4π × (10 × 10 × π) ÷ (10 × 2 × π) 2 ", and the circularity is 1. That is, in terms of circularity, a perfect circle is determined as the least complex figure. Similarly, the circularity of a square is 0.785, and the circularity of an equilateral triangle is about 0.604. The equilateral triangle is determined as a more complex figure than the square.

[0202] For an image of an irregular shape with unevenness such as the solid matter 252, the circularity is less than 0.785. Therefore, by setting the reference value of circularity to 0.785, it is possible to recognize an image with a circularity of 0.785 or more as a bubble in terms of shape recognition, while recognizing an image with a circularity of less than 0.785 as a solid matter in terms of shape recognition.

[0203] FIG. 15 is a diagram for explaining the discrimination threshold value of the digital camera. FIG. 15(a) is a diagram showing a state in which the solid matter 252 at the fine particle level is photographed, and FIG. 15(b) is a diagram showing a state in which the fine bubble 251 is photographed.

[0204] As shown in FIGS. 15(a) and 15(b), when the solid matter 252 is fine, it is recognized in the shape of a square or rectangle of 2×2 = 4 pixels, and image recognition is performed in the same square or rectangle shape as the bubble 251 shown in FIG. 15(b). Therefore, with this digital camera, it is impossible to recognize the solid matter 252 separately from the bubble 251. That is, in the case of this digital camera, the length corresponding to 2 pixels becomes the discrimination threshold value for one side.

[0205] Note that the same applies when performing shape recognition based on circularity. In a situation where the solid matter 252 and the bubble 251 are recognized in the same shape in image recognition, since there is no difference in the circularity between the two, it is impossible to recognize the solid matter 252 separately from the bubble 251.

[0206] In this way, in the imaging device 100, there is a discrimination threshold value unique to each device, and for the solid matter 252 at the fine particle level smaller than the discrimination threshold value, it is impossible to recognize it separately from the bubble 251.

[0207] Therefore, it is necessary to suppress the inflow of the solid matter 252, which is a solid matter (fine particle) smaller than this discrimination threshold value, into the measurement chamber 80.

[0208] However, it is impossible and unrealistic to completely suppress the inflow of fine particles. When the imaging device 100 captures the bubbles 251, it is sufficient that the inflow of fine particles is suppressed to such an extent that the bubbles 251 and the solid matter 252 can be distinguished from each other.

[0209] The introduction time of the bubbles 251 at which the inflow of fine particles can be suppressed to such an extent that the bubbles 251 and the solid matter 252 can be distinguished from each other is, for example, preliminarily investigated according to the shape of the introduction pipe 60, the properties of the liquid constituting the liquid 250, and the supply amount of the air supplied into the liquid 250 to form the bubbles 251 (for example, investigated with a testing machine or the like). If the opening time of the bubble introduction valve 50 is adjusted to the introduction time found by this investigation to perform bubble measurement, the inflow of the solid matter 252 (fine particles) smaller than the discrimination limit value into the measurement chamber 80 can be suppressed. Thereby, highly accurate bubble measurement becomes possible.

[0210] The specific method for investigating the bubble introduction time is performed as follows.

[0211] First, the bubble introduction valve 50 is opened for a predetermined time to collect bubbles. At this time, turbidity will also be collected. Here, the opening time of the bubble introduction valve 50 is determined according to the shape of the introduction pipe 60, the properties of the liquid 250, and the supply amount of the air supplied into the liquid 250.

[0212] Regarding the shape of the introduction pipe 60, the length and inner diameter size in the longitudinal direction of the introduction pipe 60 affect the opening time of the bubble introduction valve 50. That is, the longer the length of the introduction pipe 60, the more difficult it is for the fine particles of the solid matter 252 contained in the liquid 250 to reach the measurement chamber 80. Therefore, the longer the length of the introduction pipe 60, the longer the opening time of the bubble introduction valve 50 can be set.

[0213] On the other hand, if the inner diameter of the introduction pipe 60 is large, the liquid 250 and the solid matter 252 contained in the liquid 250 can easily pass through the introduction pipe 60, so it becomes necessary to set a short opening time for the bubble introduction valve 50. Conversely, if the inner diameter of the introduction pipe 60 is set small, the liquid 250 and the solid matter 252 contained in the liquid 250 will have difficulty passing through the introduction pipe 60, so it becomes possible to set a long opening time for the bubble introduction valve 50.

[0214] Therefore, if the length of the introduction pipe 60 is set long and the inner diameter is set small, it becomes possible to set a long opening time for the bubble introduction valve 50.

[0215] For example, when the inner diameter of the introduction pipe 60 is 50 mm or less, it has been confirmed that by setting the length of the introduction pipe 60 to 7 times or more the inner diameter, the opening time of the introduction opening valve 50 can be lengthened. Specific numerical values will be described later. Note that the inner diameter of the introduction pipe 60 is preferably 5 mm or more. Thereby, it is possible to measure the largest 4 mm bubbles among the bubbles to be measured.

[0216] Regarding the properties of the liquid 250, the particle size of the ore contained in the liquid 250 and the slurry concentration affect the opening time of the bubble introduction valve 50. The ore particle size is determined by indicators of the maximum particle size and the average particle size. The maximum particle size is literally the maximum diameter of the ore particles contained in the liquid 250. The average particle size is the average diameter of the ore particles contained in the liquid 250, and is indicated by the median diameter (D50) at which the larger side and the smaller side become equal when the particle size distribution of the ore particles is divided into two.

[0217] If the ore particle size is large, it becomes possible to set a long opening time for the bubble introduction valve 50. However, in the case of the liquid 250 with a sufficiently large ore particle size, there may be a case where turbidity does not occur during bubble measurement in the first place, and there is no need to devise a way to suppress the turbidity of the measurement chamber 80. It has been confirmed that the ore particle size at which the effect of suppressing the turbidity of the measurement chamber 80 can be obtained is such that the maximum particle size is 300 μm or less and the average particle size (median diameter D50) is less than 100 μm.

[0218] Also, regarding the slurry concentration, if the value is too large, the proportion of ore particles increases, and turbidity is likely to occur in the measurement chamber 80. Therefore, it is preferably below a predetermined value. For example, when the slurry concentration is set to less than 50 wt%, it has been confirmed that the opening time of the bubble introduction valve 50 can be set longer. When the slurry concentration is set to 50 wt% or more, the ore particles in the liquid 250 flow into the introduction pipe 60 and are likely to flow into the measurement chamber 80, making turbidity likely to occur. Therefore, it is preferable to adjust the slurry concentration to less than 50 wt%.

[0219] Regarding the amount of air supplied into the liquid 250, the smaller the supply amount, the longer the opening time of the bubble introduction valve 50 can be set. When the air supply amount increases, the bubbles 251 introduced from the bubble introduction valve 50 are likely to generate a flow, making it easier to carry ore particles into the introduction pipe 60. Therefore, from the perspective of setting the opening time of the bubble introduction valve 50 longer, it is preferable that the amount of air supplied to the liquid 250 is smaller.

[0220] Considering such parameters, the opening time of the bubble introduction valve 50 is adjusted. Among these parameters, the length of the introduction pipe 60 and the amount of air supplied to the liquid 250 are the elements that most affect the opening time of the bubble introduction valve 50.

[0221] In particular, when the introduction pipe 60 has a length of a certain level or more, for example, 20 times or more the inner diameter of the introduction pipe 60, which is 500 mm or more when expressed as a numerical value, even when the amount of air supplied into the liquid 250 increases, it is often possible to distinguish between the bubbles 251 and the solid matter 252 and perform image recognition.

[0222] It has been confirmed that the amount of air supplied into the liquid 250 is an element that has a large influence after the length of the introduction pipe 60, and this point will be described later.

[0223] In the investigation stage, while setting the above parameters, the opening time of the bubble introduction valve 50 is tentatively set accordingly. Then, with the set opening time, the bubble introduction valve 50 is opened to introduce the bubbles 251 into the introduction pipe 60. At this time, since the liquid 250 is also introduced into the introduction pipe 60, a certain degree of turbidity occurs.

[0224] Next, the liquid 250 containing the turbidity in the measurement chamber 80 and the introduction pipe 60 is extracted, and the particle size distribution of the solid matter 252 contained in the liquid 250 is determined.

[0225] If a peak in the particle size distribution of the solid matter 252 contained in the liquid 250 is observed in a particle size range smaller than the discrimination threshold value of the imaging device 100, it is determined as NG. On the other hand, if no peak in the particle size distribution of the solid matter 252 is observed in a particle size range smaller than the discrimination threshold value of the imaging device 100, it is determined as OK. Note that the discrimination threshold value of the imaging device 100 is grasped in advance.

[0226] If the determination is OK in the above determination, the opening time of the bubble introduction valve 50 set initially is adopted as the introduction time of the bubbles at which the inflow of fine particles can be suppressed to such an extent that the bubbles 251 and the solid matter 252 can be discriminated.

[0227] While changing the above parameters, such an investigation is carried out by setting the opening times of the bubble introduction valve 50 variously, determining whether a peak in the particle size distribution of the solid matter 252 contained in the liquid 250 is observed in a particle size range smaller than the discrimination threshold value of the imaging device 100, and adjusting the opening time of the bubble introduction valve 50.

[0228] At that time, while considering qualitative properties such as the longer the introduction pipe 60, the longer the opening time of the bubble introduction valve 50 can be set, and the smaller the supply amount of air into the liquid 250, the longer the opening time of the bubble introduction valve 50 can be set, the opening time of the bubble introduction valve 50 is set while making a prediction, determined, and adjusted. And since these change when the properties of the liquid 250 change, they are set respectively corresponding to the properties of the liquid 250.

[0229] As a result, it is possible to set conditions for reliably measuring the bubbles 251 with respect to various liquids 250.

[0230] Thus, according to the bubble measuring device and the bubble measuring method according to the present embodiment, corresponding to various liquids 250, an appropriate opening time of the bubble introduction valve 50 is set, the bubbles 251 are recognized separately from the solid matter 252, and bubble data such as the bubble diameter and the bubble number density can be measured accurately and reliably.

[0231] By combining such bubble measuring methods, while improving the measurement accuracy in a single transparent observation solution 260, the observation solution 260 can be easily replaced, and extremely accurate bubble measurement can be continuously and easily performed, significantly improving the accuracy and efficiency of bubble measurement.

[0232] Note that the first embodiment and the second embodiment can be combined. Since both are related to the content of bubble measurement and belong to the same technical field, they can be combined without contradiction.

[0233] As described above, the preferred embodiments of the present invention have been described in detail. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention.

[0234] This application claims the priority of the basic applications No. 2020-036982 filed with the Japan Patent Office on March 4, 2020 and No. 2020-051306 filed on March 23, 2020, and incorporates the entire contents thereof by reference herein.

Explanation of Reference Numerals

[0235] 10 Flotation cell 20 Air supply shaft 30 Agitation blade 40 Flotation machine 50 Bubble introduction valve 60 Introduction pipe 70 Frame 80 Measurement Chamber 90 Light Projector 100 Imaging Device 110 Upper Valve (First On - Off Valve) 120 Air Source 130 On - Off Solenoid Valve 140, 240 Control Unit (Control Device) 150 Ore Slurry 151 Bubbles 152 Minerals (Solids) 160 Transparent Liquid 170 Observation Solution Supply Source 180, 340 Pipes 190 Waste Liquid Tank 200, 350 Pumps 220 Air Source 230, 231, 232 On - Off Solenoid Valves 250 Liquid 251 Bubbles 252 Minerals (Solids) 260 Observation Solution 280 Measurement Chamber 320 Second On - Off Valve 330 Branch Pipe 331, 332, 333 Connection Ends 360 Observation Liquid Storage Tank

Claims

1. A bubble measuring device for measuring bubbles moving in a liquid, comprising: a measurement chamber into which bubbles in a liquid containing solids are introduced from below, and a transparent inclined surface facing obliquely downward is provided at a position where the introduced bubbles rise; an imaging device for imaging the bubbles passing through the transparent inclined surface; an introduction pipe provided below the measurement chamber for introducing the bubbles into the measurement chamber; a bubble introduction valve immersed in a liquid to be measured, for introducing and blocking the bubbles into the introduction pipe; and the opening time of the bubble introduction valve is determined according to the shape of the introduction pipe, the properties of the liquid, and the supply amount of air supplied into the liquid, and is adjusted to a predetermined time at which the bubbles and the solids contained in the liquid can be distinguished when the imaging device images the bubbles in the measurement chamber.

2. The bubble measuring device according to claim 1, wherein the introduction time of the bubbles into the introduction pipe at which the bubbles and the solids can be distinguished is adjusted to a time obtained in advance.

3. The shape of the introduction pipe includes the length of the introduction pipe, and the opening time of the bubble introduction valve is set to be longer as the length of the introduction pipe becomes longer, according to claim 1 or 2.

4. The bubble measuring device according to any one of claims 1 to 3, wherein the opening time of the bubble introduction valve is set to be longer as the supply amount of air supplied into the liquid decreases.

5. When the length of the introduction pipe is 7 times or more and less than 20 times the inner diameter of the introduction pipe, and the supply amount of air is more than 0.6 L / min and 4.0 L / min or less per 1 L of the liquid, the opening time of the bubble introduction valve is set to a predetermined time of 10 seconds or less, according to any one of claims 1 to 4.

6. When the length of the introduction pipe is 7 times or more and less than 20 times the inner diameter of the introduction pipe, and the supply amount of air is more than 0.2 L / min and 0.6 L / min or less per 1 L of the liquid, the opening time of the bubble introduction valve is set to a predetermined time of 40 seconds or less, according to any one of claims 1 to 4.

7. When the length of the introduction pipe is 20 times or more the inner diameter of the introduction pipe, and the supply amount of air is more than 0.2 L / min and 4.0 L / min or less per 1 L of the liquid, the opening time of the bubble introduction valve is set to a predetermined time of 60 seconds or less, according to any one of claims 1 to 4.

8. The bubble measuring device according to any one of claims 1 to 7, wherein the inner diameter of the introduction pipe is 5 mm or more and 50 mm or less.

9. The bubble measuring device according to any one of claims 1 to 8, wherein the bubble introduction valve is an automatic on-off valve.

10. A bubble measuring device for measuring bubbles moving in a liquid, a measurement chamber that holds the liquid, introduces the bubbles in the liquid from below, and is provided with a transparent inclined surface facing obliquely downward at a position where the introduced bubbles rise; a photographing device that photographs the bubbles passing through the transparent inclined surface; an introduction pipe provided below the measurement chamber for introducing the bubbles into the measurement chamber; a bubble introduction valve that is immersed in a liquid containing bubbles to be measured and opens and closes the introduction of the bubbles into the introduction pipe; a first on-off valve provided above the measurement chamber for blocking the supply or discharge of the observation solution to the measurement chamber; a second on-off valve provided below the measurement chamber for blocking the supply or discharge of the observation solution to the measurement chamber, comprising The bubble measuring device, wherein the opening time of the bubble introduction valve is determined according to the shape of the introduction pipe, the properties of the liquid, and the supply amount of air supplied into the liquid, and is adjusted to a predetermined time at which the bubbles and solids contained in the liquid can be distinguished when the photographing device photographs the bubbles in the measurement chamber.

11. The liquid containing the bubbles to be measured is a slurry-like liquid containing solid components, The bubble measuring device according to claim 10.

12. The liquid containing the bubbles to be measured is a liquid containing fine bubbles, The bubble measuring device according to claim 10 or 11.

13. The bubble measuring device according to any one of claims 10 to 12, wherein the second on-off valve is provided near the lower end of a region of the introduction pipe that is not immersed in the liquid.

14. a first on-off valve driving means for opening and closing the first on-off valve; a second on-off valve driving means for opening and closing the second on-off valve; a bubble introduction valve driving means for opening and closing the bubble introduction valve; a photographing means for photographing the bubbles passing through the transparent inclined surface; a photographing end detection means for detecting the end of photographing of the bubbles passing through the transparent inclined surface; an observation solution supply means for supplying a transparent observation solution to the measurement chamber Open both the first on-off valve and the second on-off valve, supply a transparent observation solution to the measurement chamber through one of the on-off valves, and discharge the observation solution from the measurement chamber through the on-off valve on the side different from the supply side. After a predetermined time has elapsed, stop the supply of the transparent observation solution, close both the first on-off valve and the second on-off valve, open the bubble introduction valve, and perform photographing of the bubbles. After a predetermined time has elapsed, close the bubble introduction valve, and control means for stopping photographing under the condition that the end of photographing is detected. The bubble measuring device according to any one of claims 10 to 13, characterized by comprising the above.

15. A pump connected to one of the first on-off valve and the second on-off valve and capable of supplying the observation solution. The bubble measuring device according to any one of claims 10 to 14, further comprising a discharge pipe connected to the other of the first on-off valve and the second on-off valve and capable of discharging the used observation solution.

16. A measurement chamber in which bubbles in a liquid containing solids are introduced from below, and a transparent inclined surface facing obliquely downward is provided at a position where the introduced bubbles rise. An imaging device for imaging the bubbles passing through the transparent inclined surface. An introduction pipe provided below the measurement chamber for introducing the bubbles into the measurement chamber. A bubble measurement method using a bubble measurement device comprising a bubble introduction valve immersed in a liquid to be measured and for introducing and blocking the bubbles into the introduction pipe. Imaging the bubbles with the imaging device, and obtaining the introduction time of the bubbles into the introduction pipe at which the bubbles and the solids contained in the liquid can be distinguished, according to the shape of the introduction pipe, the properties of the liquid, and the supply amount of air supplied into the liquid. A bubble measurement method, characterized in that the opening time of the bubble introduction valve is adjusted to the obtained introduction time of the bubbles into the introduction pipe at which the bubbles and the solids can be distinguished, and the measurement of the bubbles is performed.

17. The bubble measurement method according to claim 16, wherein the introduction time is a time obtained in advance.

18. The bubble measurement method according to claim 16 or 17, wherein the introduction time is set longer as the length of the introduction pipe becomes longer.

19. The bubble measurement method according to any one of claims 16 to 18, wherein the opening time of the bubble introduction valve is set longer as the supply amount of the air decreases.

20. The bubble measurement method according to any one of claims 16 to 19, wherein the length of the introduction pipe is not less than 7 times and less than 20 times the inner diameter of the introduction pipe, and when the supply amount of the air exceeds 0.6 L / min and is 4.0 L / min or less with respect to 1 L of the liquid, the introduction time is set to 10 seconds or less.

21. The bubble measurement method according to any one of claims 16 to 20, wherein the length of the introduction pipe is not less than 7 times and less than 20 times the inner diameter of the introduction pipe, and when the supply amount of the air exceeds 0.2 L / min and is 0.6 L / min or less with respect to 1 L of the liquid, the introduction time is set to 40 seconds or less.

22. The bubble measurement method according to any one of claims 16 to 21, wherein the length of the introduction pipe is not less than 20 times the inner diameter of the introduction pipe, and when the supply amount of the air exceeds 0.2 L / min and is 4.0 L / min or less with respect to 1 L of the liquid, the introduction time is set to 60 seconds or less.

23. The bubble measurement method according to any one of claims 16 to 22, wherein the inner diameter of the introduction pipe is 5 mm or more and 50 mm or less.

24. The bubble measurement method according to any one of claims 16 to 23, wherein the bubble introduction valve is an automatic on-off valve.

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