Flotation method and system

Abstract

To provide an ore flotation method that can efficiently perform ore flotation process even when targeting fine mineral particles including particles of 25 μm or less in particle size.SOLUTION: An ore flotation method is to separate and recover mineral particles by ore flotation process. In a target liquid, the mineral particles are made to float by using fine foam with a cell diameter of 200 μm or less and foam with a larger diameter than that of the fine foam.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a flotation method and a flotation system for use in the method. [Background technology]

[0002] The minerals contained in ore extracted from mines can be broadly divided into useful minerals (minerals containing large amounts of the target metal) and gangue minerals (minerals containing almost no target metal).The first step in recovering the target metal from the ore is the ore dressing process, and flotation, which takes advantage of the difference in hydrophobic and hydrophilic properties of the mineral surface, is widely used.

[0003] In the flotation process illustrated in Figure 1, ore mined at a copper sulfide mine is crushed and ground (the process of removing deposits and oxide films from the particle surfaces obtained after crushing), to obtain mineral powder, which is then turned into a mineral slurry. This is then subjected to rough sorting (first stage of flotation process) and refinement (second stage of flotation process), separating the slurry into float and tailings at each stage. The float is then physically separated and recovered as a useful mineral, and the tailings are stored in a tailings dam.

[0004] In the flotation process, float separation is performed by introducing air bubbles into the mineral slurry, which causes hydrophobic mineral particles to adhere to the bubbles and rise to the surface of the mineral slurry. The bubbles that float to the surface of the mineral slurry with the attached mineral particles are called "froth." "Separating as float" refers to recovering the froth by allowing it to overflow from the surface of the mineral slurry, or by scraping it off with a spatula or the like.

[0005] In the flotation process, mineral particles with hydrophilic surfaces settle in the mineral slurry, which is separated as tailings by solid-liquid separation. Therefore, when performing this flotation process, the surfaces of the valuable minerals are adjusted to be hydrophobic so that they can be recovered as float.

[0006] Here, the typical diameter of bubbles that can be generated by commercially available flotation machines is at least several millimeters. Mineral particles that easily adhere to bubbles of this size and are easily separated as float ore have a particle size of about one-tenth to several times smaller than the typical bubbles (specifically, particle size of about several tens of micrometers to 200 micrometers). However, with the decrease in high-quality ores in recent years, the amount of ores with particle sizes of about 100 micrometers to 1 mm that can be separated by efficient flotation processing has decreased, and an increasing amount of ores require crushing to small particle sizes of about 100 micrometers or less (for example, particles with particle sizes of about 20 micrometers or less).

[0007] The mineral particles mentioned above, which are very small in size compared to the air bubbles present in the flotation machine, cannot adhere to the air bubbles of the above-mentioned general particle size (at least several mm), even if they are useful mineral particles with hydrophobic surfaces. Patent Document 1 discloses an apparatus and method for recovering fine particles containing radioactive metal substances, which can recover fine particles containing radioactive metal substances from contaminated turbid water without using an adsorbent or coagulant, and which discloses a technology that can simultaneously recover fine particles containing radioactive metal substances using foam, recover fine particles containing radioactive metal substances using flocs, recover large particles containing almost no radioactive metal substances, and recover treated water containing almost no radioactive metal substances in a single tank.

[0008] Patent Document 2 discloses a method and a treatment device for oil-containing wastewater that makes it possible to reduce the amount of coagulant used compared to treatment using floatation separation. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-032034 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-165915 [Non-patent literature]

[0010] [Non-Patent Document 1] NN Rulyov; Combined microflotation of fine minerals: theory and experiment;Mineral Processing and Extractive Metallurgy, Volume 125, 2016, p 81-85 [Non-patent document 2] PTL Koh el al; Modeling attachment rates of multi-sized bubbles with particles in a flotation cell; ,Minerals Engineering 21, 2008,p.989-993 Summary of the Invention [Problem to be solved by the invention]

[0011] The present invention aims to provide a flotation method that can efficiently perform flotation treatment even when targeting fine mineral particles, including particles with a particle size of approximately 25 μm or less. [Means for solving the problem]

[0012] The flotation method in this embodiment is a flotation method for separating and recovering mineral particles by a flotation process, in which fine bubbles having a bubble diameter of 200 μm or less and bubbles having a diameter larger than the fine bubbles are used in a treatment liquid containing the mineral particles to float the mineral particles in the treatment liquid.

[0013] The flotation system in this embodiment is a flotation system that separates and recovers mineral particles by flotation processing, and is equipped with a flotation device having a micro-bubble generator that introduces micro-bubbles with a bubble diameter of 200 μm or less into a liquid to be treated that contains the mineral particles, a flotation tank that stores the liquid to be treated and causes the mineral particles to float above the liquid to be treated within the tank, and a bubble generator that introduces bubbles with a diameter larger than the micro-bubbles into the liquid to be treated. [Effects of the Invention]

[0014] According to the present invention, even when targeting fine mineral particles including particles with a particle size of about 25 μm or less, flotation treatment can be carried out efficiently. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a diagram showing the flow of a flotation process. [Figure 2] 1 is a diagram showing an outline of the configuration of a flotation apparatus used in a flotation method. [Figure 3] 1 is a diagram showing an outline of the configuration of a flotation apparatus used in a flotation method. [Figure 4] FIG. 1 is a diagram showing the results of flotation treatment in Example 1 and Comparative Example 1. [Figure 5] FIG. 1 is a diagram showing the results of flotation treatment in Example 2 and Comparative Example 2. [Figure 6] FIG. 1 is a diagram showing the results of flotation treatment in Example 3 and Comparative Example 3. DETAILED DESCRIPTION OF THE INVENTION

[0016] Generally, bubbles are gases in a medium surrounded by an interface. Of these, bubbles with a volume-equivalent diameter of less than 100 μm are called fine bubbles, bubbles with a diameter of 1 μm or more but less than 100 μm are called microbubbles, and bubbles with a diameter of less than 1 μm are called ultrafine bubbles. In this embodiment, these bubbles are hereinafter referred to as fine bubbles. Here, the volume-equivalent diameter refers to the diameter derived based on the volume of the bubble assuming a spherical shape.

[0017] Specific embodiments will be described in detail below. Note that the present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope of the present invention.

[0018] <Flow of flotation treatment> Figure 1 is a diagram showing the flow of a flotation process that can be carried out using the flotation method of the present invention. Below, we will first briefly explain the flow of this flotation process, and then explain in detail a specific embodiment of the flotation method of the present invention.

[0019] [Ore crushing and grinding] In the flotation process, the ore to be processed is crushed to obtain a mixture of valuable minerals and gangue minerals. Because the separation process after the crushing process is a physical separation, it is ideal for the particles of the mixture to be either single particles of valuable minerals or gangue minerals (hereinafter also referred to as "liberation"). The intensity of the crushing is adjusted depending on the size of the minerals contained in the ore.

[0020] When crushing ore using a general crushing device such as a ball mill, the lower limit of the particle size of the powder mixture that can be crushed while maintaining good economic efficiency is approximately 100 μm. However, in recent years, the size of minerals contained in ore has become finer, approximately 25 μm or less, making it difficult to achieve sufficient liberation by crushing to the above-mentioned general particle size (approximately 100 μm). Therefore, ultra-fine crushers such as bead mills are sometimes used to crush ore to approximately 25 μm or less.

[0021] After crushing the ore, the resulting mineral particles are subjected to a grinding process. Grinding is an operation to remove deposits and oxide films from the surface of the crushed particles. This operation is performed immediately before the flotation process (the "rough selection" or "cleaning" described below) to clean the particle surfaces. This operation also prevents variations in the effectiveness of additives (flotation agents) added during the flotation process, such as collectors, inhibitors, and flocculants, which are used to treat the surface of the mineral particles.

[0022] [Rough selection / Selected] Rough sorting (rough sorting) and refinement (refining) are the main steps in the flotation process, in which particles from the crushed powder mixture are brought into contact with air bubbles to separate particles that adhere to the air bubbles from those that do not, based on the difference in hydrophilicity or hydrophobicity of the particle surface.

[0023] In the roughing and refining processes, the mixed powder and granules are first mixed with a liquid such as water or seawater to form a slurry (mineral slurry). When preparing the ore slurry, the solids ratio is usually adjusted taking into account the efficiency of the input of the mineral slurry and the amount of concentrate recovered. Furthermore, to increase the difference in wettability between the surfaces of the useful mineral particles and the gangue mineral particles, a flotation agent may be added to the ore slurry to modify the surface properties and liquid phase properties of the slurry to the desired properties suitable for flotation processing. In this specification, such mineral particle modification operations are referred to as "conditioning."

[0024] Here, the basic mechanism of flotation is to introduce air bubbles into a mineral slurry, and by taking advantage of the difference in surface properties (wettability) between useful mineral particles and gangue mineral particles, the useful minerals, which have hydrophobic surfaces, are attached to the air bubbles, and the useful minerals are recovered as "float minerals," while the gangue minerals are separated as "sink minerals."

[0025] In this type of treatment, flotation agents added for "conditioning" include those that adsorb to mineral surfaces to change their surface properties and those that change the properties of the liquid phase of the mineral slurry. For example, known agents that change the properties of mineral surfaces include collectors (e.g., sodium, xanthate, ethyl xanthate) that impart hydrophobic properties to mineral surfaces, and inhibitors (e.g., gelatin, lactic acid, starch) that do not. Other known agents that change the properties of the liquid phase of the mineral slurry include pH adjusters (e.g., hydrochloric acid, hydrogen peroxide, caustic soda, lime) that adjust the pH, and foaming agents (e.g., MIBC, pine oil, cresylic acid) that dissolve in the mineral slurry to generate stable bubbles.

[0026] In the flotation process, the particle surface properties and the liquid phase in the mineral slurry are adjusted to appropriate conditions by either charging a pre-conditioned mineral slurry into a flotation apparatus, or by adding the above-mentioned flotation agents to the slurry, or by performing both operations as necessary. Note that the conditioning may be performed before introducing air bubbles into the mineral slurry after it has been charged into the flotation apparatus.

[0027] In the flotation process, the mineral slurry is agitated and air bubbles are introduced into the flotation device, causing the air bubbles to attach to the more hydrophobic particles in the mixed powder and granular material in the slurry. As a result, the mineral particles attached to the air bubbles float to the surface of the mineral slurry, forming a froth. Meanwhile, the less hydrophobic particles sink to form tailings.

[0028] The mineral slurry is stirred by adjusting the size of the equipment, the amount of mineral slurry introduced, and also the floating speed and amount of bubbles introduced, which are usually adjusted to a size of about several mm, to be optimal.

[0029] As shown in Figure 1, rough sorting is the so-called first stage of ore dressing treatment, and refinement is the so-called second stage of ore dressing treatment. The float obtained by rough sorting, which is the first stage of ore dressing treatment, is subjected to grinding treatment again (regrinding), and then refinement, which is the second stage of ore dressing treatment, is performed.

[0030] <Flotation method> The flotation method of the present invention (hereinafter also simply referred to as "flotation method") is a method for separating and recovering fine mineral particles including particles of about 25 μm or less from a liquid to be treated (ore slurry) by flotation treatment.

[0031] In a flotation process, by introducing fine bubbles with a bubble diameter of 50 μm to 200 μm, fine particles with a particle diameter of approximately 25 μm or less can be attached to the fine bubbles to form a froth (see Non-Patent Documents 1 and 2). However, in a flotation process targeting fine mineral particles with a particle diameter of approximately 25 μm or less, the fine bubbles have a low rising speed, resulting in insufficient froth generation and sometimes requiring a long time for froth generation.

[0032] The "flotation method" in this embodiment is a process in which fine bubbles with a diameter of 200 μm or less and bubbles with a diameter larger than the fine bubbles are used to float mineral particles as float in a treatment liquid (ore slurry) to be subjected to flotation treatment. Furthermore, in this embodiment, a fine bubble generator that generates microbubbles will be mainly described, but bubbles smaller than 1 μm (ultrafine bubbles) may also be included.

[0033] For example, a device that generates fine bubbles with a diameter of about 50 μm to 200 μm can be used. This fine bubble generator has a mechanism that generates fine bubbles of a desired diameter by, for example, passing air supplied to the device through a porous body and causing the bubbles to become finer as they are precipitated to the outside, and then rotating the porous body to cause the bubbles to detach from the surface of the porous body before they become coarse.

[0034] In addition to the fine bubbles, the "bubbles having a diameter larger than the fine bubbles" that are allowed to coexist in the liquid to be treated are preferably bubbles having a diameter of 1.0 mm to 1.5 mm, for example.

[0035] [First embodiment of the "flotation method"] The above-mentioned "flotation method" is an embodiment (first embodiment) in which a fine bubble generator is attached to the above-mentioned general-purpose flotation apparatus having the function of generating the above-mentioned "bubbles larger in diameter than the fine bubbles," and bubbles ("fine bubbles") having a bubble diameter of 50 μm or more and 200 μm or less are generated from the fine bubble generator in the liquid to be treated (ore slurry), and bubbles larger in size than the bubbles generated from the fine bubble generator are generated in the ore slurry from the flotation apparatus.

[0036] According to this "flotation method," by introducing bubbles with a diameter of 50 μm to 200 μm ("fine bubbles") together with larger bubbles, the apparent rising speed of the fine bubbles increases as the larger bubbles rise in the mineral slurry at a faster rate than the fine bubbles to which mineral particles tend to adhere. As a result, the time required to form the froth can be shortened.

[0037] [Flotation System] 2 is a diagram showing the outline of the configuration of a flotation system 1A that can be suitably used in the first embodiment of the flotation method described above. The flotation system 1A includes a flotation apparatus 11 that performs flotation processing, and a micro-bubble generator 12 that is attached to the flotation apparatus 11 and generates micro-bubbles and introduces them into the liquid to be treated (ore slurry). In the flotation system 1A, pressure reducing valves (flow valves) 13 and 14 are connected to the flotation apparatus 11 and the micro-bubble generator 12, respectively, to reduce the pressure of the pressurized gas supplied from a pressurized gas supply device (compressor) 2, thereby enabling adjustment of the flow rate.

[0038] (Flotation equipment) The flotation apparatus 11 has a flotation tank that performs flotation treatment on an ore slurry containing fine mineral particles fed into it, and a bubble generator that generates bubbles and introduces them into the liquid to be treated (ore slurry). Such a flotation apparatus 11 can be configured, for example, by a mechanical Denver flotation machine.

[0039] The bubble generating section of the flotation apparatus 11 generates bubbles with a diameter larger than the bubbles ("fine bubbles") with a diameter of 50 μm to 200 μm generated from the fine bubble generating device 12, and introduces these bubbles into the liquid to be treated (ore slurry) contained in the flotation tank. The bubble generating section generates bubbles using air taken in from outside the apparatus or pressurized gas (pressurized air) supplied from a connected pressurized air supply device. Specifically, the diameter of the bubbles generated in the flotation apparatus 11 is not particularly limited as long as it is larger than the fine bubbles ("fine bubbles") to be introduced, but it is preferable that the diameter be 1.0 mm to 2.0 mm.

[0040] (Micro-bubble generator) In the flotation system 1A, a fine bubble generator 12 is attached and connected to the flotation device 11. The fine bubble generator 12 generates fine bubbles that are smaller in size than the bubbles generated by the flotation device 11 and have a bubble diameter of 50 μm or more and 200 μm or less.

[0041] The microbubble generator 12 is not particularly limited as long as it can generate the above-mentioned microbubbles, and a general-purpose product that is easy to obtain and install can be used. One example of such a microbubble generator is a microbubble generator having a porous body made of micropores inside and a mechanism for micronizing the air by passing the supplied air through the porous body.

[0042] The micro-bubble generator 12 generates micro-bubbles and introduces the micro-bubbles into the ore slurry contained inside the flotation apparatus 11. The micro-bubble generator 12 generates micro-bubbles based on air taken in from outside the apparatus or pressurized gas (pressurized air) supplied from a connected pressurized air supply apparatus.

[0043] In this way, in the flotation system 1A, by attaching the fine bubble generator 12 to the flotation device 11, it is possible to generate fine bubbles with a bubble diameter of 50 μm to 200 μm and bubbles with a diameter larger than the fine bubbles, i.e., two types of bubbles of different sizes, in the ore slurry to be processed.

[0044] (pressure reducing valve) Furthermore, it is preferable that the flotation system 1A is provided with pressure reducing valves (flow rate valves) 13 and 14 in each of the flotation device 11 and the fine bubble generator 12, which reduce the pressure of the pressurized air supplied from the pressurized gas supply device (compressor) 2 to enable adjustment of the flow rate.

[0045] The pressure reducing valves 13, 14 are adjustment valves that reduce the pressure of the pressurized air supplied from the pressurized gas supply device 2 to maintain a constant pressure, and can also adjust the flow rate of the reduced pressure air. As a result, the pressure reducing valves 13, 14 can adjust the flow rate of the bubbles generated from the devices that supply the reduced pressure air, i.e., the flotation device 11 and the fine bubble generator 12. Therefore, the pressure reducing valves 13, 14 are also called "flow rate valves 13, 14" that adjust the flow rate of the bubbles.

[0046] In the flotation systems 1A and 1B, pressure reducing valves 13 and 14 are individually installed in the flotation device 11 and the connecting pipe 15 to the pressurized gas supply device 2, and in the connecting pipe 16 to the fine-bubble generator 12 and the pressurized gas supply device 2. Therefore, air supplied from the pressurized gas supply device 2 can be supplied to the flotation device 11 and the fine-bubble generator 12 while controlling the flow rates individually. Since the flow rates of air supplied to the flotation device 11 and the fine-bubble generator 12 correlate with the flow rates of bubbles generated from each device (11, 12), the flow rates of fine bubbles (bubbles with a bubble diameter of 50 μm to 200 μm) introduced into the ore slurry and the flow rates of bubbles larger than the fine bubbles can be individually and appropriately adjusted by controlling the pressure reducing valves (flow rate valves) 13 and 14.

[0047] As described above, by introducing fine bubbles with a diameter of 50 μm to 200 μm into a mineral slurry containing fine mineral particles, the fine mineral particles can be favorably attached to the bubbles to form a fine froth. Furthermore, by simultaneously introducing bubbles with a diameter larger than the fine bubbles, the bubbles with a higher upward velocity in the treatment liquid rise in the mineral slurry, thereby increasing the apparent upward velocity of the fine bubbles and shortening the time required for froth formation.

[0048] In this case, flow rate valves 13 and 14 are provided separately for the flotation device 11 and the fine bubble generator 12, and the flow rate of the bubbles generated from each device (11, 12) can be adjusted individually. This allows the bubbles to adhere to the fine mineral particles and the time required for froth formation to be shortened by increasing the speed at which the bubbles rise to the slurry surface, efficiently and appropriately.

[0049] If a single flow valve is used for the flotation device 11 and the fine bubble generator 12, for example, when the valve is operated to increase the flow rate of the fine bubble generator, the flow rate on the flotation device 11 side will decrease, making it impossible to effectively increase the speed at which the slurry rises to the surface. Similarly, when the valve is operated to increase the flow rate of the flotation device 11, for example, the flow rate on the fine bubble generator side will decrease, making it impossible to introduce a sufficient amount of fine bubbles, which will prevent them from adhering to the fine mineral particles, resulting in a decrease in the recovery rate of the float ore.

[0050] The bubble flow rate adjustment, in other words, the ratio between the flow rate of the fine bubbles generated by the fine bubble generator 12 and the flow rate of the bubbles generated by the flotation device 11, is not particularly limited. For example, it can be appropriately set depending on the concentration of solids (mineral particles) in the mineral slurry to be subjected to flotation, the size of the mineral particles, the desired flotation time (the time required for froth formation), and other factors. Furthermore, since the time required for froth formation varies depending on the viscosity of the liquid phase of the mineral slurry due to the addition of a flotation agent and the difference in hydrophilicity between the useful minerals and gangue minerals that make up the mineral particles, it is preferable to appropriately set the flow rate ratio based on these conditions. Furthermore, a flotation test may be performed as part of the conditioning operation prior to the flotation process, and a suitable flow rate ratio may be selected from the results of the test.

[0051] If the flow rate of bubbles (bubbles generated by the flotation device 11) that are larger in diameter than the fine bubbles generated by the fine-bubble generator 12 is too high, the rising speed of the fine bubbles will become too high, which may reduce the opportunity for the fine bubbles to come into contact with, for example, fine mineral particles. Alternatively, even if the fine bubbles come into contact with and adhere to fine mineral particles, they may fall off during the process of floating up to the surface of the ore slurry.

[0052] The flow rate of the bubbles can be adjusted by controlling the flow rate valves 13 and 14 by controlling the opening of the valves.

[0053] 3 is a diagram showing an outline of the configuration of a flotation system according to another embodiment of the present invention, which is used in the flotation method. The flotation system 1B includes a flotation apparatus 11 that performs flotation processing, and a fine-bubble generator 12 that is attached to the flotation apparatus 11 and generates and introduces fine bubbles. The flotation apparatus 11 and the fine-bubble generator 12 are each individually connected to pressure reducing valves (flow valves) 13 and 14 that reduce the pressure of the pressurized gas to adjust the flow rate. The flotation system 1B differs from the flotation system 1A in that pressurized gas supply devices 2a and 2b are individually connected to the pressure reducing valves 13 and 14.

[0054] As shown in Fig. 3, in the flotation system 1B, a pressurized gas supply device 2a is connected to the flotation device 11 via a pipe 15, and a flow valve 13 is provided on the pipe 15. Furthermore, a pressurized gas supply device 2b is connected to the fine-bubble generator 12 via a pipe 16, and a flow valve 14 is provided on the pipe 16. The pressurized gas supply device 2a and the pressurized gas supply device 2b are separate devices, and air is supplied to the device (flotation device 11 or fine-bubble generator 12) connected at the end of the pipes 15, 16 by independent control from each device (2a, 2b).

[0055] Even with this configuration, the pipes 15, 16 are provided with flow valves 13, 14, respectively, to adjust the flow rates of the air supplied from the pressurized gas supply devices 2a, 2b, making it possible to individually adjust the flow rates of the bubbles generated from the flotation device 11 and the fine bubble generator 12. This makes it possible to efficiently shorten the time required for froth formation by increasing the adhesion of bubbles to fine mineral particles and the speed at which they rise to the slurry surface.

[0056] In addition, in the flotation system 1B, the configuration is the same as that of the flotation system 1A, except that the pressurized gas supply devices 2a and 2b are provided separately, and the explanation of the other configurations is the same as that described above, so the explanation will be omitted here.

[0057] [Second embodiment of the "flotation method"] The "flotation method" of this embodiment is an embodiment (second embodiment) in which, during the flotation process in which treated mineral particles are floated as float using a flotation device, microbubble-containing water containing "microbubbles" is injected into the liquid to be treated (ore slurry) in advance.

[0058] Also in the second embodiment, a general-purpose device capable of generating bubbles with a diameter exceeding 200 μm in the liquid to be treated can be used as the flotation device.

[0059] In this second embodiment, water containing fine bubbles with a bubble diameter of 200 μm or less may be used without attaching the fine bubble generator 12 to the flotation apparatus 11. For example, water containing fine bubbles may be produced in the required amount using a separately prepared fine bubble generator 12. However, it is also possible to obtain water containing fine bubbles mixed in advance from another location within the factory or from another factory and add this to the flotation treatment at an appropriate time. Such an embodiment in which the fine bubble generator 12 is not attached to the flotation apparatus 11 is also within the technical scope of the present invention.

[0060] When carrying out the "flotation method" of the second embodiment, if the flotation treatment is carried out continuously over a plurality of stages as shown in Fig. 1, an appropriate amount of microbubble-containing water containing microbubbles may be injected into the liquid to be treated (ore slurry) to be charged into the first stage of flotation treatment ("rough selection" in Fig. 1). Alternatively, if necessary, an appropriate amount of microbubble-containing water may be injected individually into the liquid to be treated (ore slurry) to be charged into each of the other treatments that are sequentially carried out downstream, such as the second stage of flotation treatment ("cleaning" in Fig. 1).

[0061] Furthermore, in the second embodiment, the flow rates of the "fine bubbles" and the "bubbles with a diameter larger than that of the fine bubbles" can be individually adjusted to the optimum amounts as appropriate, as in the first embodiment, thereby enabling more accurate ore dressing processing. [Example]

[0062] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to the following examples in any way.

[0063] [Example 1, Comparative Example 1] The minerals to be treated were crushed using a bead mill and sieved to obtain a mixed mineral powder containing fine mineral particles of 20 μm (P80) or less. Table 1 below shows the results of elemental analysis (unit: wt%) of the obtained mixed powder.

[0064] [Table 1]

[0065] Next, water was added to the resulting powder mixture and mixed to obtain a mineral slurry. Calcium hydroxide was added to the mineral slurry to adjust the pH to 8.5. A foaming agent (methyl isobutyl carbinol: MIBC) was added at 15 g / t, collector F4244 (Flottec, model number 4244) at 86 g / t, and diesel oil at 34 g / t, and the mixture was conditioned (for 1 minute).

[0066] Next, the prepared ore slurry was subjected to a four-stage flotation treatment for a total of 30 minutes. In the flotation treatment of Example 1, a flotation apparatus whose schematic configuration is shown in Figure 2 was used. That is, an apparatus equipped with a microbubble generator (a carbon ceramic rotary microbubble generator, manufactured by Ansai Kantetsu Co., Ltd.) was used.

[0067] The flotation device used was a mechanical Denver flotation device. The fine bubble generator generated fine bubbles with a diameter of 100 μm to 150 μm ("fine bubbles"), and the mechanical Denver flotation device generated bubbles with a diameter larger than the "fine bubbles" (1.0 mm to 1.5 mm), making it possible to adjust the flow rate of each of the bubbles generated from the fine bubble generator and the mechanical Denver flotation device.

[0068] On the other hand, in the flotation treatment of Comparative Example 1, a conventional treatment was carried out using an apparatus consisting of only a mechanical Denver flotation machine without a microbubble generating device.

[0069] Figure 4 shows the results of flotation treatments in Example 1 and Comparative Example 1, and is a graph showing the relationship between flotation time and Cu recovery rate. As shown in this graph, in Example 1, in which a microbubble generator was installed to introduce "microbubbles" into the ore slurry as well as larger bubbles, the Cu recovery rate was improved. Furthermore, for example, when the Cu recovery rate was 30%, the flotation time in Example 1 was approximately 8 minutes, while the flotation time in Comparative Example 1 was approximately 30 minutes, meaning that Example 1 was able to significantly shorten the flotation time.

[0070] [Example 2, Comparative Example 2] In Example 2, the same treatment as in Example 1 was carried out, except that the flotation apparatus used was the flotation apparatus whose schematic configuration is shown in Figure 3. That is, the flotation apparatus used was an apparatus in which a flotation apparatus (mechanical Denver flotation machine) and a compressor connected to a fine bubble generator were separately provided.

[0071] The flotation device used was a mechanical Denver flotation device. The fine bubble generator generated fine bubbles ("fine bubbles") with a diameter of 100 μm to 150 μm, and the mechanical Denver flotation device generated bubbles larger than the fine bubbles (diameter 1.0 mm to 1.5 mm), making it possible to adjust the flow rate of each of the bubbles generated from the fine bubble generator and the mechanical Denver flotation device.

[0072] On the other hand, in the flotation treatment of Comparative Example 2, similar to Comparative Example 1, a conventional treatment was carried out using an apparatus consisting of only a mechanical Denver flotation machine without a microbubble generator attached.

[0073] Fig. 5 is a graph showing the results of flotation treatment in Example 2 and Comparative Example 2, showing the relationship between flotation time and Cu recovery rate. As shown in this graph, in Example 2, the Cu recovery rate was improved. In addition, the flotation time was significantly reduced.

[0074] [Example 3, Comparative Example 3] In Example 3, the treatment was the same as in Examples 1 and 2, except that a powder mixture having the composition shown in Table 1 was mixed with the liquid to be treated, "water containing fine bubbles" to which fine bubbles had been added beforehand. Because fine bubbles were added beforehand, the water contained mainly ultrafine bubbles of 1 μm or less. On the other hand, in Comparative Example 3, conventional treatment was carried out using an apparatus consisting only of a mechanical Denver flotation machine, without using water containing fine bubbles.

[0075] 6 is a graph showing the results of flotation treatment in Example 3 and Comparative Example 3, showing the relationship between flotation time and Cu recovery rate. As shown in this graph, in Example 3 as well, the Cu recovery rate at a flotation time of 30 minutes was improved compared to Comparative Example 3. [Explanation of symbols]

[0076] 1A, 1B Flotation System 11 Flotation equipment 12 Microbubble generator 13, 14 Pressure reducing valve (flow valve) 15, 16 Connection piping 2, 2a, 2b Pressurized gas supply device (compressor)

Claims

1. A flotation method for separating and recovering mineral particles by flotation, comprising: The flotation treatment uses fine bubbles having a bubble diameter of 1 μm to 200 μm and bubbles having a diameter larger than that of the fine bubbles in a treatment target liquid containing the mineral particles, thereby floating the mineral particles above the treatment target liquid, a microbubble generator is attached to the flotation apparatus, and the microbubbles are generated in the liquid to be treated from the microbubble generator; The flotation device generates bubbles having a diameter larger than the fine bubbles in the liquid to be treated, adjusting the flow rates of the fine bubbles and bubbles having a diameter larger than that of the fine bubbles in the liquid to be treated; A flotation method in which the micro-bubble generator and the flotation device are each provided with a flow rate valve, and the flow rate of bubbles generated from each device is individually adjusted according to the desired flotation time.

2. The fine bubble generating device and the flotation device are each individually connected to a pressurized gas supply device.

2. The method of claim 1.

3. The mineral particles include particles of 25 μm or less.

3. The flotation method according to claim 1 or 2.

4. A flotation system for separating and recovering mineral particles by flotation, comprising: a microbubble generator for introducing microbubbles having a bubble diameter of 1 μm or more and 200 μm or less into the liquid to be treated containing the mineral particles; a flotation apparatus including a flotation tank for storing the liquid to be treated and causing the mineral particles to float above the liquid to be treated within the tank, and a bubble generating unit for introducing bubbles having a diameter larger than that of the fine bubbles into the liquid to be treated, The flotation device and the micro-bubble generating device are each provided with a flow rate valve, and the flow rate of bubbles generated from each device is individually adjusted according to the desired flotation time. Flotation systems.

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