JP7534072B2 - Froth bubble movement direction measuring device and method, and flotation device and method using the same - Google Patents

Description

The present invention relates to a froth bubble movement direction measuring device and a froth bubble movement direction measuring method, as well as a flotation device and a flotation method using these.

Conventionally, flotation has been known as a method for separating valuable components from other components in minerals when recovering the valuable components contained in the minerals (see, for example, Patent Document 1). In this flotation method, the minerals are crushed and mixed with a liquid such as water to form a slurry, and air is blown into the slurry. Then, the crushed materials that have a high affinity for air rise to the surface, and the crushed materials can be separated into the floating ones and the rest. In flotation, multiple reagents such as foaming agents and collectors are added to the slurry to make the crushed materials float with the air, and the crushed materials containing the desired valuable components are made to float with the air by adjusting the reagents added.

In this flotation process, the separation performance for separating the pulverized material into floating and other materials (i.e., pulverized material that sinks) changes depending on the amount of air blown into the slurry. For example, if a large amount of air is blown into the slurry, the pulverized material containing the desired valuable components will tend to float and recovery will improve, but other pulverized materials will also tend to float. For this reason, if a large amount of air is blown into the slurry, the recovered pulverized material will contain more impurities. Therefore, in order to improve the recovery of pulverized material containing the desired valuable components while increasing the quality of the recovered pulverized material, it is necessary to appropriately control the amount of air blown into the slurry.

The grade and recovery rate are determined by adjusting the reagents, the amount of air, the rotation speed of the flotation machine's impeller (rotating blades), etc., but currently, as an indicator of this, a qualitative judgment is made by visually observing not only the size of the froth bubbles that rise to the top of the flotation machine, but also the speed and direction of movement of the froth bubbles.

JP 2013-180289 A

However, the conventional method of qualitative judgment based on visual inspection left a large margin of error for operators, making it difficult to properly adjust the reagents, air volume, impeller (rotating blade) speed, etc.

The present invention aims to provide a froth bubble movement direction measuring device and a froth bubble movement direction measuring method that measure the froth bubble movement direction inline using image processing and digitize it in real time, as well as a froth bubble movement direction measuring device and a froth bubble movement direction measuring method that use these.

In order to achieve the above object, a froth bubble movement direction measuring device according to one aspect of the present invention includes a light source that irradiates light onto an upper surface of a flotation tank;
an imaging means capable of imaging at least a part of an upper surface of the flotation tank with a predetermined imaging time difference;
image processing means for processing images captured by the imaging means with the predetermined imaging time difference;
and a calculation means for calculating a moving direction of the froth bubble from the image having the predetermined image capturing time difference processed by the image processing means ,
the imaging means is capable of capturing continuous still images having the predetermined imaging time difference;
The calculation means obtains the movement vector of the froth bubbles from the degree of overlap of the froth bubbles detected in each of the continuous still images captured by the imaging means, and calculates the movement direction of the froth bubbles by converting the movement vector into a coordinate system set up within the flotation tank .

The present invention allows for quantitative measurement of the froth bubble movement direction, compared to qualitative visual judgment, making it possible to adjust the reagent, air volume, and impeller (rotor) speed in real time with high accuracy.

1 is a schematic diagram showing the configuration of a froth bubble movement direction measuring device and a flotation device according to an embodiment of the present invention. FIG. FIG. 13 is a diagram to explain why the top of the froth bubble shines whiter than the surrounding area. FIG. 13 is a diagram showing an example of an image of a froth bubble captured from above by an area scan camera. FIG. 11 illustrates the correlation between reflected light size of a floss bubble and the actual size of the floss bubble. 1 is an image of a froth bubble image at a certain point in time (t=n, where t is time and n is a natural number). 6 is an image of the froth bubble image at the next time point (t=n+1) in FIG. 5 which is successively captured. 7 is a superimposed image of the froth foam of FIG. 5 and FIG. 6. FIG. 13 is a diagram for explaining a method for converting the movement direction of froth bubbles into a movement direction adapted to the shape of a circular flotation tank. FIG. 2 is a flow diagram showing an example of a process flow of a froth bubble diameter measurement method and a flotation method according to an embodiment of the present invention.

Below, we will explain the form for implementing the present invention with reference to the drawings.

Figure 1 is a schematic diagram showing the configuration of a froth bubble movement direction measuring device and a flotation device according to an embodiment of the present invention. The froth bubble movement direction measuring device 100 according to an embodiment of the present invention comprises a light source 60, an area scan camera 70, a connection cable 80, and a computer 90. The computer 90 comprises, for example, an image processing unit 91 and an arithmetic processing unit 92.

The flotation apparatus 150 according to this embodiment also includes a flotation machine 50 in addition to the froth bubble movement direction measuring device 100. The flotation machine 50 includes a flotation tank 10, an agitator blade 20, and an air supply shaft 30. As a related component of the flotation apparatus 150, an ore slurry 40 is stored in the flotation tank 10.

That is, the flotation device 150 is configured by combining a flotation machine 50 and a froth bubble movement direction measuring device 100.

The flotation machine 50 according to this embodiment can be any of a variety of commonly used flotation machines. The flotation device 150 according to this embodiment is characterized by the froth bubble movement direction measuring device 100, but we will first explain the flotation machine 50.

The flotation tank 10 is a slurry storage means for storing liquid ore slurry 40 containing crushed material to be subjected to ore-dressing. Since the crushed material is useful metals to be subjected to ore-dressing or concentration, flotation is performed with the ore slurry 40 stored in the flotation tank 10. Therefore, although not shown in FIG. 1, the flotation tank 10 may have an extraction port at the top of the flotation tank 10 for extracting useful metals, and a discharge port for discharging tailings that are not to be subjected to useful metals.

The agitator blade 20 is a froth bubble refinement means for finely refining the froth bubbles 41 generated by air supplied from the lower end of the air supply shaft 30. When the froth bubbles 41 generated at the lower end of the air supply shaft 30, i.e., below the agitator blade 20, rise, they collide with the agitator blade 20 due to the rotation of the agitator blade 20, thereby reducing the froth bubble diameter. Reducing the froth bubble diameter can increase the collision efficiency with the ore particles in the ore slurry 40. In addition to the froth bubble diameter and froth bubble movement speed, the movement direction of the froth bubbles 41 affects the recovery of the crushed material containing the desired valuable components.

Crushed material (ore particles) with metal surfaces on the surface adhere to the froth bubbles and rise in the ore slurry 40, while other crushed material does not adhere to the froth bubbles 41 and sinks to the bottom of the flotation tank 10. In this case, it is preferable to generate froth bubbles 41 that have an appropriate movement direction to which the crushed material can easily adhere, taking into consideration the balance between the size of the crushed material to be sorted and the buoyancy of the froth bubbles 41. For this reason, a froth bubble movement direction measuring device 100 is provided to measure the froth bubble movement direction.

As described above, the froth bubble movement direction measuring device 100 includes a light source 60, an area scan camera 70, a connection cable 80, and a computer 90, with at least the light source 60 and the area scan camera 70 positioned above the flotation tank 10.

The light source 60 is a light emitting means or lighting means for illuminating the top surface of the ore slurry 40 from above. As long as it can illuminate the top surface of the ore slurry 40 from above, various light emitting means or lighting means can be used for the light source 60. By irradiating the top surface of the ore slurry 40 with light from above, the tops of the froth bubbles 41 present in the ore slurry 40 shine whiter than the surrounding areas of the froth bubbles 41, and the tops shine with a higher brightness than the surrounding areas. In other words, in the image obtained by the area scan camera 2 by irradiating the froth bubbles 41 with light from the light source 60, the tops of the froth bubbles shine whiter than the bases of the froth bubbles.

The area scan camera 70 is an imaging means for imaging the upper surface of the ore slurry 40 from above and acquiring an image including the froth bubbles 41. In this embodiment, an example is given in which the area scan camera 70 is used, but various imaging means can be used as long as they can image a partial area or the entire area of the ore slurry 40. In this embodiment, it is sufficient for the area scan camera 70 to be able to image the area irradiated with light by the light source 60, and it is not necessarily necessary for it to be able to image the entire surface of the flotation tank 10.

Figure 2 is a diagram to explain why the top of the floss bubble 41 shines whiter than the surrounding area. As shown in Figure 2, when light emitted from the light source 60 hits the floss bubble 41 and is reflected, the light near the top of the floss bubble 41 is reflected upward where the area scan camera 70 is located, whereas the light that hits the base of the floss bubble 41 is reflected diagonally upward or to the side.

Figure 3 shows an example of an image of such a floss bubble 41 captured from above by an area scan camera 70. As shown in Figure 3, the image shows a white glowing area (reflected light area) 42 in the center of the floss bubble 41.

The size of the white glowing part is determined by the size and curvature of the froth bubbles 41, so the curvature of the froth bubbles 41 may vary slightly depending on the composition of the ore slurry 40. However, as shown in FIG. 2, the difference in brightness of the froth bubbles 41 depending on the position is due to the froth bubbles 41 being approximately spherical in shape, so it can be assumed that the difference due to the composition of the ore slurry 40 is only slight and is generally constant. In that case, it can be said that the size of the froth bubbles 41 is correlated with the size of the white glowing part. Factors that determine the size of the white glowing part 42 include the size of the light emitting surface of the light source 60, the distance from the top surface of the froth bubbles 41 to the light source 60, and the distance from the top surface of the froth bubbles 10 to the area scan camera 70, in addition to the size and curvature of the froth bubbles 41 described above, but all of these can be excluded as factors if the conditions are not changed.

The area scan camera 70 is connected to a computer 90 via a network, and images obtained from the area scan camera 70 are input to the computer 90. The images from the area scan camera 70 may be transmitted by wired communication via a connection cable 80, or may be transmitted by wireless communication.

The computer 90 is equipped with a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), etc., and has a structure that reads and operates programs. The computer 90 functions as a calculation processing means that performs calculation processing to calculate the froth bubble diameter based on the images acquired from the area scan camera 70. The computer 90 also has an image processing unit 91, and has the function and structure to process the images acquired from the area scan camera 70.

Figure 4 shows the correlation between the size of reflected light of a floss bubble and the actual size of the floss bubble. In Figure 4, the correlation between the size of reflected light when light is irradiated onto the floss bubble 41 and the actual measured size of the floss bubble 41 is calculated in advance as a relational equation, which is used to measure the size of the floss bubble 41. That is, in Figure 4, the horizontal axis shows the reflected light size of the floss bubble 41, and the vertical axis shows the size of the floss bubble 41. By plotting these measured values, a certain degree of correlation can be confirmed in the graph plotting the size of the white glowing part and the size of the bubble. A regression equation can then be approximated from this relationship.

In Figure 4, the curve showing the correlation between the plotted points is the approximate regression equation. It can be seen that the approximate regression equation shown in Figure 4 is not a straight line but a polynomial. Once created, such an approximate regression equation can be generally generalized and applied regardless of the composition of the ore slurry 40.

The area scan camera 70 is configured to be capable of capturing images of the floss foam 41 in succession at a predetermined imaging time difference. In other words, it is configured to be capable of capturing images continuously at a predetermined imaging interval. This makes it possible to capture multiple images at a predetermined imaging time difference, and to record the changes in the state of the floss foam 41 at the predetermined imaging time difference as images.

Figure 5 is an image of a floss foam image at a certain point in time (t=n, where t is time and n is a natural number), and Figure 6 is an image of the floss foam image at the next point in time (t=n+1) after Figure 5, which is successively captured. Also, Figure 7 is an image of the floss foam obtained by superimposing Figure 5 and Figure 6.

For example, if the imaging period is T, then at each point in time t=T, 2T, 3T, ... nT, (n+1)T, ... the area scan camera 70 captures the imaging area continuously (intermittently in terms of the flow of time) and obtains an image for each imaging period.

Figure 5 is an image captured (obtained) at t = nT, and in Figure 5, each of the six floss bubbles 411a to 416a is present at a different position in the captured image.

Figure 6 is an image captured (obtained) at t = (n + 1) T. In Figure 6, six floss bubbles 411b-416b are present at different positions in the captured image. When Figure 5 and Figure 6 are compared individually, the difference is not very clear.

Figure 7 is an image in which Figures 5 and 6 are superimposed, and the positional deviation between floss bubbles 411a to 416a in Figure 5 and floss bubbles 411b to 416b in Figure 6 can be seen.

The direction of this positional shift between Figures 5 and 6 is the direction of movement of floss bubbles 411-416 at time difference T. Here, the direction of movement can be represented by a vector connecting the start point and end point of the positions of the floss bubbles moved by time difference T. The direction of the vector is the direction from the start point to the end point of floss bubbles 411-416, and indicates the direction of movement of floss bubbles 411-416. In other words, the start point is the position of floss bubbles 411a-416a, and the end point is the position of floss bubbles 411b-416b. The magnitude of the vector represents the distance moved. Such a vector will be referred to as a movement vector.

The calculation processing unit 92 considers that the same floss bubbles 411-416 have moved when the floss bubbles 411a-416a at time t=nT overlap with time t=(n+1)T. In this way, since the movement of the same floss bubbles is considered to be based on the degree of overlap of the floss bubbles between images, it is desirable to capture images at a sufficiently fast imaging rate. Specifically, it is preferable that the imaging time difference T is a time difference such that the distance traveled by the floss bubbles 411-416 falls within the diameter of the floss bubbles 411-416.

It is desirable that the light emitted from the light source 60 be surface-emitted light with a narrow directional angle that covers the imaging area and is as uniform as possible. This is because a narrow directional angle makes it easier to create contrast in the white-glowing areas.

The overlap between the floss bubbles 411-416 can be calculated by finding the diameter of the floss bubbles 411-416, or the white light shining parts can be compared. In either case, the comparison is often made between areas near the center of the white light, so there is no difference in the calculation process.

Furthermore, it is not necessary to compare the centers of the white shining parts, but it is also possible to compare the edges of the floss bubbles 411-416. Because the centers and edges of the floss bubbles 411-416 move in parallel, the direction of movement can be obtained by obtaining the movement vector between the start and end points of the same positions on the edges of the floss bubbles 411-416. In other words, any point on the floss bubbles 411-416 can be used as the measurement point, as long as the position within the floss bubbles 411-416 before and after the movement is the same.

In this way, from the two images acquired in the imaging period T, the movement direction of each froth bubble 411-416 on a two-dimensional plane (the upper surface of the ore slurry 40) at the time difference T can be determined.

It is difficult to capture images of the froth bubbles 41, 411 to 416t in the ore slurry 40, so the image capture will essentially be of the movement of the froth bubbles 41, 411 to 416 in the plane on the top surface of the ore slurry 40.

Here, in terms of the behavior of the froth bubbles 411-416, the efficient movement direction is for the froth bubbles to move from the center of the flotation tank 10 toward the outside and overflow. In order to quantify whether the froth bubbles 411-416 are moving from the center of the flotation tank 10 toward the outside, it is necessary to determine the movement direction in the image and then convert it into a movement direction that matches the shape of the circular flotation tank.

Figure 8 is a diagram to explain how to convert the movement direction of the froth bubbles into a movement direction that matches the shape of a circular flotation tank.

As shown in Figure 8, a line A is used to connect the start and end points of the movement of the froth bubbles 417, 418, and the movement vectors P, Q of the froth bubbles 417, 418 are obtained. Then, a line B is used to connect the midpoint of line A indicating the movement vectors P, Q to the center C of the flotation machine. The opening angle between line A and line B is set as the direction of froth bubble movement in the flotation machine. In this way, the relationship between the directions of the movement vectors P, Q and the center C of the flotation tank 10 can be understood.

Here, the angle between the midpoint of the movement vector P of the froth bubble 417 and the center C of the flotation tank is close to 90 degrees. And the movement is along the circumferential direction of the flotation tank 10, not from the center toward the outside of the flotation tank 10, which is an undesirable movement direction for froth bubbles.

On the other hand, the movement vector Q of the froth bubble 418 is in the direction of movement from the center to the outside, which indicates the preferred behavior of the froth bubble. In this case, the angle between the movement vector Q of the froth bubble 418 and the line B connecting the center C of the flotation tank 10 is an angle that is close to 180 degrees. Therefore, it can be said that the preferred opening angle between the movement vector and the center C of the flotation tank 10 is an angle that is close to 180 degrees.

On the other hand, as shown by the movement vector P, if the opening angle of the line connecting the midpoint of the movement vector P and the center C of the flotation tank 10 is close to 90 degrees, the behavior of the froth bubbles can be said to be undesirable.

By measuring the movement direction of the froth bubbles 411-418 in this way, it is possible to determine whether the movement direction of the froth bubbles 411-418 is preferable, and by adjusting the conditions of the agitator blade 20, etc., the flow of the froth bubbles 411-418 can be made preferable.

The flotation machine 50 is generally cylindrical, with the drive unit of the agitator blades 20 for cutting the supply air to produce fine bubbles located at the center of the top, so it is physically difficult to image the entire surface from above the flotation machine 50. However, the state of the froth bubbles 41, 411-418 does not depend on the location, so it can be represented by imaging only a portion of it. Therefore, a field of view that can image a portion of the top surface of the flotation machine 50 is sufficient, and the height of the camera and the height of the lens from the top surface of the flotation machine 50 can be determined accordingly. For example, Figure 8 shows an example in which the image area is slightly less than half of the flotation tank 10. As explained above, this field of view is sufficient for measuring the direction of the froth bubbles.

The image processing unit 91 also performs various image processing operations to remove noise from the image and increase contrast to facilitate calculation processing. For example, if a binary image is obtained from an image acquired by setting a predetermined threshold value, it becomes easier to determine the size of the froth bubbles 41, 411-418. Such processing is performed in the image processing unit 91. The image processing unit 91 may be provided inside the computer 90, or may be provided separately outside the computer 90.

In FIG. 1, the positions of the light source 60 and the area scan camera 70 are shown diagrammatically, but fixing means can be provided depending on the application, and they can be fixed in appropriate positions.

In addition, although the components other than the flotation tank 10, the stirring blades 20, and the air supply shaft 30 are not shown in the flotation machine 50, it goes without saying that the flotation machine 50 may be equipped with various components necessary to configure the flotation device 150.

Based on the measured movement direction of the froth bubbles 41, 411-418, the amount of air blown into the slurry, the reagents, and the rotation speed of the flotation machine's impeller (rotating blades) can be adjusted to improve the conditions of the froth bubbles 41.

As explained in Figures 2 to 4, it is also possible to calculate the diameter of the floss bubbles 41, 411 to 418, but by determining both the diameter and the direction of movement of the floss bubbles 41, 411 to 418, the conditions for the floss bubbles can be adjusted to be even better. Furthermore, the speed of movement of the floss bubbles 41, 411 to 418 can also be determined, and by making adjustments taking into account the diameter, direction and speed of movement of the floss bubbles, it is possible to generate floss bubbles very efficiently.

The movement speed of the froth foam is calculated by dividing the movement distance by the time T, since the magnitude of the movement vector obtained by continuously capturing images of the froth foam at a predetermined time interval T represents the movement distance.

In other words, the movement speed of the floss bubbles 411-416 is calculated by simply dividing the movement distance of the center of the floss bubble in a two-dimensional plane by the imaging time difference (imaging period) T.

For example, if the distance traveled (the magnitude of the movement vector) of floss bubble 411 between time t = nT and time t = (n+1)T is d, then the movement speed can be calculated as d/T. This is similar for each of floss bubbles 412-416, and if applied to each of floss bubbles 411-416, the movement speed can be calculated for each of floss bubbles 411-416.

In this way, it is possible to calculate the direction of movement of the froth bubbles 41, 411 to 418, or even the speed of movement if necessary, and adjust the conditions based on this, or to automate feedback control to improve the condition of the froth bubbles 41, 411 to 418.

In this way, the flotation apparatus 150 according to this embodiment can be configured to easily and accurately adjust the froth bubbles by incorporating the froth bubble movement direction measuring device 100 into various flotation machines 50.

Next, we will explain the process flow of the froth bubble movement direction measurement method and flotation method according to an embodiment of the present invention.

Figure 9 is a flow diagram showing an example of the process flow of the froth bubble movement direction measurement method and the flotation method according to an embodiment of the present invention. Note that the components described so far are given the same reference numerals and their description will be omitted.

In FIG. 9, in step S100, the light source 60 irradiates the upper surface of the ore slurry 40 stored in the flotation tank 10 with light. This causes the top portions of the froth bubbles 41 in the ore slurry 40 to glow white. Note that the top portions correspond to approximately the centers of the froth bubbles 41, as described in FIGS. 2 and 3.

In step S110, the area scan camera 70 captures an image of the top surface of the ore slurry 40, and obtains a first image captured from the top surface of the ore slurry 40. The obtained first image includes froth bubbles 411a-416a having white glowing portions 42. The obtained image data is transmitted to the computer 90 via wired or wireless communication.

In step S120, the area scan camera 70 captures an image of the top surface of the ore slurry 40, and obtains a second image captured from the top surface of the ore slurry 40. The obtained second image includes froth bubbles 411b-416b having white glowing portions 42, but the positions of the froth bubbles 411b-416b are different from the positions of the froth bubbles 411a-416a in the first image. The obtained image data is transmitted to the computer 90 via wired or wireless communication.

In step S130, the image processing unit 91 performs image processing on the two images received. For example, the image processing involves obtaining a binarized image from the received images using a predetermined threshold value. This removes noise from the images obtained by the area scan camera 70.

In the above flow, the second image is acquired after the first image is acquired, but it is also possible to perform image processing of the first image after the first image is acquired, and then perform image processing of the second image after the second image is acquired.

In step S140, the calculation processing unit 92 of the computer 90 performs calculation processing to calculate the movement direction (direction of the movement vector) between the froth bubbles 411a-416a, 417, 418 that are the starting points and the froth bubbles 411b-416b, 417, 418 that are the ending points, and calculates the opening angle between the movement vectors P and Q and the center C of the flotation tank 10. At this time, the computer 90 may simultaneously calculate the size of the froth bubbles 411-418 from the size of the reflected light using a pre-stored approximate regression equation. Furthermore, if necessary, the movement speed of the froth bubbles 411-418 may be calculated.

As shown in step S150, various adjustment processes may be performed based on the measured froth bubble movement direction. As described above, the air supply conditions and mixing conditions can be optimized so that the froth bubbles 411 to 418 flow along the radial direction from the center C of the flotation tank 10 toward the outer periphery. Such adjustments may be performed by a human looking at the froth bubble measurement results, or by the computer 90 using automatic control. When a human makes the adjustments, the computer 90 outputs the measurement results to a display or the like. When the computer 90 performs automatic adjustments, the computer 90 adjusts the output of the air supply shaft 30, the drive speed of the mixing blades 20, etc. based on the measurement results. Needless to say, the measurement results may also be output at that time. From this perspective, step S150 is not essential and may be performed as needed.

In this way, the froth bubble movement direction measurement method and flotation method according to this embodiment can automatically measure the froth bubble movement direction, and can also make adjustments to optimize the froth bubble movement direction as necessary, enabling high-quality flotation to be performed.

The above describes in detail preferred embodiments of the present invention, but 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.

10 Flotation tank 20 Agitator blade 30 Air supply shaft 40 Ore slurry 41, 411 to 418, 411a to 416a, 411b to 416b Froth foam 42 White shining part (reflected light area)
50 Flotation machine 60 Light source 70 Area scan camera 80 Connection cable 90 Computer 91 Image processing unit 92 Processing unit 100 Froth bubble movement direction measuring device 150 Flotation device

Claims (6)

A light source that irradiates light onto an upper surface of the flotation tank;
an imaging means capable of imaging at least a part of an upper surface of the flotation tank with a predetermined imaging time difference;
image processing means for processing images captured by the imaging means with the predetermined imaging time difference;
and a calculation means for calculating a moving direction of the froth bubble from the image having the predetermined image capturing time difference processed by the image processing means ,
the imaging means is capable of capturing continuous still images having the predetermined imaging time difference;
The calculation means of the froth bubble movement direction measuring device obtains the movement vector of the froth bubble from the degree of overlap of the froth bubble detected in each of the consecutive still images captured by the imaging means, and calculates the movement direction of the froth bubble by converting the movement vector into a coordinate system set up within the flotation tank . The froth bubble movement direction measuring device of claim 1, wherein the calculation means connects a straight line from the midpoint between the start point and the end point of the movement vector of the froth bubble to the center of the flotation tank, and calculates the opening angle between the movement vector and the straight line as the movement direction of the froth bubble. A flotation tank;
A stirring blade provided in the flotation tank;
an air supply means provided in the flotation tank;
3. A froth bubble movement direction measuring device according to claim 1 or 2 , which is provided outside the flotation tank. irradiating an upper surface of the flotation tank with light;
taking images of at least a portion of an upper surface of the flotation tank with a predetermined imaging time difference to obtain images having the predetermined imaging time difference;
an image processing step of processing the acquired images having the predetermined imaging time difference;
and calculating a moving direction of the froth bubble from the image having the predetermined image capturing time difference processed in the image processing step,
In the step of acquiring the images, continuous still images having the predetermined image capturing time difference are captured,
In the process of calculating the movement direction of the froth bubbles, the movement vector of the froth bubbles is obtained from the degree of overlap of the froth bubbles detected in each of the successive still images, and the movement vector is converted into a coordinate system set up within the flotation tank, thereby calculating the movement direction of the froth bubbles . A froth bubble movement direction measuring method as described in claim 4, wherein in the step of calculating the movement direction of the froth bubble, a straight line is drawn between the midpoint between the start point and the end point of the movement vector of the froth bubble and the center of the flotation tank, and the opening angle between the movement vector and the straight line is calculated as the movement direction of the froth bubble. A method for measuring a direction of movement of a froth bubble according to claim 4 or 5 ,
and adjusting froth foam generation conditions based on the calculated movement direction of the froth foam.

Images