A cold-state active oil bubble preparation device and flotation method for low-rank coal flotation

Abstract

The present invention relates to a cold-state active oil bubble preparation device and a flotation method for low-rank coal flotation, belonging to the technical field of low-rank coal flotation, and solving the problems of heating required for oil bubble flotation and poor safety in the prior art. The present invention includes an active collector delivery pipeline, a clear water delivery pipeline, a gas delivery pipeline, and an oil bubble generator. The clear water delivery pipeline, the active collector delivery pipeline, and the gas delivery pipeline are communicated with the feed inlet of the oil bubble generator. The internal structure of the oil bubble generator of the present invention is simple, without a heating device, and can generate stable active oil bubbles, which can meet the requirements of different production scales and different coal qualities in different periods.

Description

Technical Field

[0001] The present invention relates to the technical field of low-rank coal flotation, and in particular to a cold-state active oil bubble preparation device and a flotation method for low-rank coal flotation. Background Art

[0002] As a key energy source and industrial raw material in my country, coal provides a crucial guarantee for socio-economic development and energy security. As of 2021, national coal production reached 4.13 billion tons, of which low-rank coal accounted for over 55% of the total. As the main coal-producing areas shift westward, low-rank coal production will continue to increase, leading to increasing attention for its development and utilization. With the increasing use of mechanized coal mining, the quality of the mined coal is deteriorating. Furthermore, low-rank coal is characterized by low metamorphism, poor quality, and brittleness, leading to a sharp increase in slime content and ash content. The efficient flotation of low-rank coal slime has attracted considerable attention from industry insiders. Due to its low metamorphism, high content of water and oxygen functional groups, and extensive surface porosity, low-rank coal has poor flotation properties, making clean coal recovery difficult and resulting in resource waste. To improve clean coal recovery, collector dosages must be increased, but this leads to high slime flotation costs and subsequent slime water treatment difficulties, impacting the economic benefits of coal enterprises.

[0003] Flotation studies on various difficult-to-separate minerals have shown that activated oil bubble flotation exhibits superior capture and selectivity compared to conventional flotation, proving to be a more effective technique. However, the production of the bubbles and the dispersion of the oil droplets require high temperatures to vaporize the droplets, which presents a number of safety risks in practice, significantly limiting the widespread application of oil bubble flotation. Furthermore, the heating and vaporization of the oil droplets necessitates the use of water-soluble surfactants to avoid damage to the heating apparatus. Summary of the Invention

[0004] In view of the above analysis, the embodiments of the present invention aim to provide a cold-state active oil bubble preparation device and flotation method for low-rank coal flotation, so as to solve the problem that the existing oil bubble flotation requires heating and has poor safety.

[0005] On the one hand, the present invention provides a cold-state active oil bubble preparation device for low-rank coal flotation, including an active collector delivery pipeline, a clean water delivery pipeline, a gas delivery pipeline and an oil bubble generator, wherein the clean water delivery pipeline, the active collector delivery pipeline and the gas delivery pipeline are connected to the feed port of the oil bubble generator.

[0006] Furthermore, the feed inlet includes a first feed inlet, the clean water delivery pipeline includes a water storage tank, and the water storage tank is connected to the first feed inlet.

[0007] Further, the active collector delivery pipeline includes a chemical dosing tank and a stirring tank. The chemical dosing tank delivers the surfactant that has been stirred evenly into the stirring tank, and the stirring tank is used to stir and mix the surfactant and the collector added into it.

[0008] Further, the feed inlet includes a second feed inlet, and the stirring tank is communicated with the second feed inlet.

[0009] Further, the gas delivery pipeline includes an air compressor and a gas storage tank. The air compressor compresses the inhaled dry air and stores it in the gas storage tank.

[0010] Further, the feed inlet includes a third feed inlet, and the gas storage tank is communicated with the third feed inlet.

[0011] On the other hand, the present invention provides a cold-state active oil bubble flotation method for low-rank coal flotation. Using the above-mentioned cold-state active oil bubble preparation device, the steps include:

[0012] Step S1: Preparation of active collector, clear water and air;

[0013] Step S2: Open the solenoid valves in the clear water delivery pipeline, the active collector delivery pipeline and the gas delivery pipeline, so that clear water, active collector and dry air enter the oil bubble generator;

[0014] Step S3: Adjust the opening degrees of the flow regulating valves in the active collector delivery pipeline, the clear water delivery pipeline and the gas delivery pipeline until stable active oil bubbles are generated in the oil bubble generator;

[0015] Step S4: The active oil bubbles generated by the oil bubble generator are inhaled into the flotation column through the air inlet of the bubble generator; the bubble generator relies on the negative pressure generated by the circulating pump to circulate the coal slurry to inhale the active oil bubbles, and further pulverizes them and mineralizes them with the circulating pulp.

[0016] Further, the oil bubble generator is communicated with the air inlet of the bubble generator, and the circulating pump is arranged between the flotation column and the bubble generator.

[0017] Further, in the step 1, after adding the surfactant into the chemical dosing tank and stirring it evenly, it is added into the stirring tank through the first peristaltic pump and the first liquid flowmeter to be mixed and stirred evenly with the collector.

[0018] Further, in the step 2, the solenoid valves in the clear water delivery pipeline, the active collector delivery pipeline and the gas delivery pipeline are opened simultaneously or sequentially.

[0019] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0020] (1) The internal structure of the oil bubble generator of the present invention is simple, consisting of only three annular micro pipelines; without a heating device, it relies only on the rapid flow and shear of the liquid in the microchannels to efficiently generate stable active oil bubbles; the size, quantity, and oil film thickness of the oil bubbles can be precisely controlled by adjusting the flow rate to meet the requirements of different production scales and different coal qualities at different times.

[0021] (2) The collector after cold-state bubble generation of the present invention is evenly dispersed in the pulp, avoiding the problem of uneven dispersion of traditional collectors by mechanical stirring, and greatly reducing the dosage of flotation collectors.

[0022] (3) The cold-state active oil bubble flotation of the present invention with controllable particle size and oil film thickness has good mineralization effect. Due to the good dispersion of the oil bubbles and the large effective collision probability with mineral particles, the flotation effect is improved, and the selectivity and clean coal recovery rate of flotation are increased.

[0023] In the present invention, the above technical solutions can also be combined with each other to achieve more preferred combination schemes. Other features and advantages of the present invention will be described in the subsequent specification, and some advantages can be made obvious from the specification or understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained from the content specifically pointed out in the specification and the drawings. Description of the Drawings

[0024] The drawings are only for the purpose of showing specific embodiments and are not considered as limitations of the present invention. Throughout the drawings, the same reference signs denote the same components.

[0025] Figure 1 It is a schematic structural diagram of the active oil bubble preparation device of the present invention;

[0026] Figure 2 It is a schematic diagram of the internal structure pipeline of the oil bubble generator of the present invention and the oil bubble generation process;

[0027] Figure 3 It is Figure 2 the A-A cross-sectional view of

[0028] Figure 4 It is a schematic structural diagram of the active oil bubble flotation device of the present invention.

[0029] Reference Signs:

[0030] 1 - Oil bubble generator; 11 - First microchannel; 12 - Second microchannel; 13 - Third microchannel; 14 - Oil bubble output pipeline; 21 - Chemical dosing tank; 22 - Stirring tank; 23 - First peristaltic pump; 24 - First liquid flowmeter; 25 - Second peristaltic pump; 26 - Second liquid flowmeter; 27 - First flow regulating valve; 28 - First solenoid valve; 31 - Water storage tank; 32 - Third peristaltic pump; 33 - Third liquid flowmeter; 34 - Second flow regulating valve; 35 - Second solenoid valve; 41 - Air compressor; 42 - Air storage tank; 43 - Gas flowmeter; 44 - Pressure gauge; 45 - Third flow regulating valve; 5 - Bubble generator; 6 - Flotation column; 7 - Circulation pump. Detailed implementation manners

[0031] The following will specifically describe the preferred embodiments of the present invention in conjunction with the accompanying drawings. Among them, the accompanying drawings form a part of the present invention and are used together with the embodiments of the present invention to explain the principle of the present invention, rather than to limit the scope of the present invention.

[0032] Embodiment 1

[0033] A specific embodiment of the present invention, as Figures 1-3 shown, discloses a cold-state active oil bubble preparation method for low-rank coal flotation. The steps include:

[0034] Step S1: Preparation of active collector, clear water and air.

[0035] After adding the surfactant to the chemical dosing tank 21 and stirring evenly; it is added to the stirring tank 22 through the first peristaltic pump 23 and the first liquid flowmeter 24 and stirred evenly (in the mixture of surfactant and collector, the proportion of surfactant is 1-3 wt%). After the first solenoid valve 28 is opened, it is transported to the inlet of the second microchannel 12 through the pipeline.

[0036] It should be noted that both ionic and non-ionic surfactants can be used, and preferably anionic surfactants among ionic surfactants, such as palmitic acid, sulfates, sulfonates, etc.

[0037] A first solenoid valve 28 is provided on the active collector delivery pipeline to control the opening and closing of the output pipeline of the stirring tank 22. The spherical float self-locking devices in the chemical dosing tank 21 and the stirring tank 22 are used to control the liquid level heights of their respective tanks.

[0038] The water storage tank 31 is connected to the first microchannel 11 of the oil bubble generator 1. After the second solenoid valve 35 is opened, clear water enters the oil bubble generator 1 through the inlet of the first microchannel 11. The liquid level height in the water storage tank 31 is controlled by the spherical float self-locking device, and the second solenoid valve 35 controls the opening and closing of the output pipeline of the water storage tank 31.

[0039] The air compressor 41 compresses and stores the inhaled dry air in the air storage tank 42. After the third solenoid valve (not shown in the figure) is opened, the pressurized dry air enters the oil bubble generator 1 through the feed port of the third microchannel 13. The third solenoid valve controls the opening and closing of the output pipeline of the air storage tank 42.

[0040] Step S2: Open the solenoid valves in the clear water delivery pipeline, the active collector delivery pipeline, and the gas delivery pipeline (the second solenoid valve 35, the first solenoid valve 28, and the third solenoid valve in this embodiment), so that clear water, active collector, and dry air enter the oil bubble generator 1 and respectively fill the first microchannel 11, the second microchannel 12, and the third microchannel 13.

[0041] It should be noted that in this step, the first solenoid valve 28, the second solenoid valve 35, and the third solenoid valve can be opened simultaneously or not simultaneously, but it is necessary to ensure no backflow. Preferably, in this embodiment, the first solenoid valve 28, the second solenoid valve 35, and the third solenoid valve are opened synchronously.

[0042] Step S3: After the three micro pipelines are filled, adjust the opening degrees of the flow regulating valves in the active collector delivery pipeline, the clear water delivery pipeline, and the gas delivery pipeline (the first flow regulating valve 27, the second flow regulating valve 34, and the third flow regulating valve 45 in this embodiment) until stable active oil bubbles are generated in the first microchannel 11; regulate the pressure indication in the pipeline through the pressure gauge 44.

[0043] Compared with the prior art, the cold-state active oil bubble preparation method provided in this embodiment has an oil bubble generator including three annular microchannels, without a heating device, and only relies on the rapid flow shear of the liquid in the microchannels to efficiently generate stable active oil bubbles; the active collector delivery pipeline, the clear water delivery pipeline, and the gas delivery pipeline are respectively connected to the corresponding feed ports of the three annular microchannels of the oil bubble generator, and can prepare stable active oil bubbles with a large adjustable size range and an easily controllable oil film thickness.

[0044] Embodiment 2

[0045] Another specific embodiment of the present invention, as Figures 1-3 shown, discloses a cold-state active oil bubble preparation device (hereinafter referred to as the cold-state active oil bubble preparation device) for low-rank coal flotation, used for the preparation of the cold-state active oil bubbles in Embodiment 1, including an active collector delivery pipeline, a clear water delivery pipeline, a gas delivery pipeline, and an oil bubble generator 1. The oil bubble generator 1 includes three coaxial microchannels, and the clear water delivery pipeline, the active collector delivery pipeline, and the gas delivery pipeline are respectively connected to the feed ports of the three microchannels from the outside to the inside of the oil bubble generator 1.

[0046] Compared with the prior art, the cold-state active oil bubble preparation device provided in this embodiment has an oil bubble generator including three annular microchannels. Without a heating device, it can efficiently generate stable active oil bubbles only by the rapid flow and shear of the liquid in the microchannels. The active collector delivery pipeline, the clear water delivery pipeline, and the gas delivery pipeline are respectively connected to the corresponding feeding ports of the three annular microchannels of the oil bubble generator, capable of preparing stable active oil bubbles with a large adjustable size range and an easily controllable oil film thickness, reducing the dosage of the flotation collector.

[0047] As Figure 2 , Figure 3 shown, the oil bubble generator 1 includes a first microchannel 11, a second microchannel 12, and a third microchannel 13 arranged coaxially. The second microchannel 12 is located between the first microchannel 11 and the third microchannel 13. The feeding ports of the first microchannel 11, the second microchannel 12, and the third microchannel 13 are on the same side. The discharge ports of the first microchannel 11, the second microchannel 12, and the third microchannel 13 are connected, and the discharge ports of the second microchannel 12 and the third microchannel 13 are located within the first microchannel 11. The media flowing out from the second microchannel 12 and the third microchannel 13 merge into the first microchannel 11.

[0048] In this embodiment, the clear water delivery pipeline, the active collector delivery pipeline, and the gas delivery pipeline are respectively connected to the feeding ports of the first microchannel 11, the second microchannel 12, and the third microchannel 13. As Figure 2 shown, an oil bubble output pipeline 14 is provided at the lower end of the discharge port of the first microchannel 11. The media flowing out from the discharge ports of the first microchannel 11, the second microchannel 12, and the third microchannel 13 enter the oil bubble output pipe 14, and the formed oil bubbles are discharged from the oil bubble output pipeline 14.

[0049] The active collector delivery pipeline includes a chemical dosing tank 21 and a stirring tank 22. The chemical dosing tank 21 is used for stirring the surfactant added into it, and the surfactant stirred evenly in the chemical dosing tank 21 is transported into the stirring tank 22. After the collector and the surfactant in the stirring tank 22 are mixed evenly, they are transported to the feeding port of the second microchannel 12 through a pipeline.

[0050] A first peristaltic pump 23 is provided between the chemical dosing tank 21 and the stirring tank 22. The surfactant stirred evenly in the chemical dosing tank 21 is transported into the stirring tank 22 by the power provided by the first peristaltic pump 23.

[0051] In order to achieve precise and reasonable proportioning of the chemicals, a first liquid flowmeter 24 is also provided between the first peristaltic pump 23 and the stirring tank 22.

[0052] In this embodiment, by setting a high-precision first liquid flow meter 24 in the pipeline between the dosing box 21 and the mixing barrel 22, the volume of the collector and surfactant entering the mixing barrel 22 can be accurately determined, thereby achieving accurate and reasonable proportioning of the reagents.

[0053] A second peristaltic pump 25, a second liquid flow meter 26 and a first flow regulating valve 27 are provided in the pipeline between the stirring barrel 22 and the feed port of the second microchannel 12. Specifically, the second liquid flow meter 26 and the first flow regulating valve 27 are located between the second peristaltic pump 25 and the second microchannel 12.

[0054] The collector and surfactant, uniformly mixed in the mixing drum 22, are delivered to the inlet of the second microchannel 12 by the power provided by the second peristaltic pump 25. A high-precision second liquid flowmeter 26 displays the flow rate of the active collector in real time. The flow rate of the active collector entering the oil bubble generator 1 is regulated by adjusting the opening of the first flow control valve 27 in the pipeline.

[0055] In order to facilitate the control of the opening and closing of the active collector delivery pipeline, a first solenoid valve 28 is provided on the active collector delivery pipeline. The first solenoid valve 28 is provided downstream of the stirring barrel 22, specifically between the stirring barrel 22 and the second peristaltic pump 25, and is used to control the opening and closing of the output pipeline of the stirring barrel 22.

[0056] The clean water delivery pipeline includes a water storage tank 31 and a third peristaltic pump 32 . The clean water in the water storage tank 31 is delivered to the oil bubble generator 1 through the third peristaltic pump 32 and enters the oil bubble generator 1 through the feed port of the first microchannel 11 .

[0057] In order to accurately control the flow of clean water, the clean water delivery pipeline further includes a third liquid flow meter 33 and a second flow regulating valve 34 , which are arranged between the third peristaltic pump 32 and the oil bubble generator 1 .

[0058] In this embodiment, the high-precision third liquid flow meter 33 provided in the clean water delivery pipeline displays the flow of clean water in real time; the opening of the second flow regulating valve 34 in the clean water delivery pipeline is adjusted to control the flow of clean water entering the oil bubble generator 1.

[0059] In order to facilitate the control of the opening and closing of the clean water delivery pipeline, the clean water delivery pipeline also includes a second solenoid valve 35, which is arranged between the water storage tank 31 and the third peristaltic pump 32, and is used to control the opening and closing of the output pipeline of the water storage tank 31.

[0060] It should be noted that the dosing box 21, the mixing barrel 22 and the water storage tank 31 are all equipped with a liquid level maintaining device, namely a spherical float self-locking device, so as to keep the liquid level in the container at an appropriate level and provide continuous and stable incoming materials for downstream equipment.

[0061] The gas delivery pipeline includes an air compressor 41 and a gas storage tank 42. The air compressor 41 compresses the inhaled dry air and stores it in the gas storage tank 42. To precisely control the amount and pressure of the air entering the oil bubble generator 1, the gas delivery pipeline further includes a gas flowmeter 43, a pressure gauge 44, and a third flow regulating valve 45, which are provided between the gas storage tank 42 and the third microchannel 13.

[0062] Understandably, to facilitate the control of the on / off of the gas delivery pipeline, a third solenoid valve (not shown in the figure) is further included in the gas delivery pipeline. The third solenoid valve is provided downstream of the gas storage tank 42, specifically located between the gas storage tank 42 and the gas flowmeter 43, and is used to control the opening and closing of the output pipeline of the gas storage 42.

[0063] In this embodiment, clear water, the uniformly stirred active collector, and dry air enter the oil bubble generator 1 through the feed ports of the first microchannel 11, the second microchannel 12, and the third microchannel 13 respectively. Peristaltic pumps, solenoid valves, flow regulating valves, and liquid flowmeters are provided on the active collector delivery pipeline, the clear water delivery pipeline, and the air delivery pipeline, which can monitor the flow rate entering the oil bubble generator 1 in real time and adjust the size, speed, and oil film thickness of the active oil bubbles generated in the oil bubble generator 1.

[0064] In this embodiment, the solenoid valves in each delivery pipeline are opened to allow clear water, the active collector, and air to enter the oil bubble generator 1 and fill the three annular microchannels of the first microchannel 11, the second microchannel 12, and the third microchannel 13 respectively, so as to eliminate the influence of the residual air in the first microchannel 11 and the second microchannel 12 on the preparation of active oil bubbles.

[0065] In this embodiment, after the three annular microchannels of the oil bubble generator 1 are filled with the corresponding liquid and air, the second solenoid valve 35 in the clear water delivery pipeline is closed, and by adjusting the opening degrees of the flow regulating valves (the first flow regulating valve 27 and the third flow regulating valve 45) in the active collector and dry air delivery pipelines, the flow rate and flow velocity of the collector and air in the second microchannel 12 and the third microchannel 13 are regulated until the air is sheared by the flowing active collector at the ends of the second microchannel 12 and the third microchannel 13 to stably generate oil-in-gas bubbles.

[0066] In this embodiment, after the air bubbles in the oil enter the rear-end fine pipeline (oil bubble output pipeline 14) under the push of the subsequent collector, the second solenoid valve 35 is opened, the opening degree of the air and active collector pipeline flow regulating valve is kept unchanged, and the opening degree of the second flow regulating valve 34 in the clear water pipeline is adjusted to control the clear water flow rate and velocity in the first microchannel 11 until the active oil bubbles can be stably generated by the flowing clear water shearing the collector containing bubbles. By regulating the changes in the clear water flow rate and velocity in the first microchannel 11, a large range of fluid shear forces are generated at the ends of the three microchannels, so as to generate stable active oil bubbles with a large adjustable size range and an easily controllable oil film thickness, so as to meet the requirements of different production scales and different coal qualities in different periods.

[0067] Example 3

[0068] Another specific embodiment of the present invention is as Figure 4 shown, and discloses a cold-state active oil bubble flotation device for low-rank coal flotation (hereinafter referred to as the cold-state active oil bubble flotation device), which includes the cold-state active oil bubble preparation device of Example 3, and also includes a bubble generator 5, a flotation column 6 and a circulation pump 7. The air inlet of the bubble generator 5 is connected to the oil bubble generator 1. Specifically, the air inlet of the bubble generator 5 is connected to the oil bubble output pipeline 14. The circulation pump 7 is arranged between the flotation column 6 and the bubble generator 5. The active oil bubbles generated by the oil bubble generator 1 are sucked into the flotation column 6 through the air inlet of the bubble generator 5. The bubble generator 5 relies on the negative pressure generated by the high-speed circulation of the coal slurry by the circulation pump 7 to suck the active oil bubbles, and further pulverizes and mineralizes them with the circulating pulp.

[0069] Compared with the prior art, the cold-state active oil bubble flotation device provided in this embodiment has an oil bubble generator including three annular microchannels, without a heating device, and only relies on the rapid flow shear of the liquid in the microchannels to efficiently generate stable active oil bubbles; the active collector delivery pipeline, the clear water delivery pipeline and the gas delivery pipeline are respectively connected to the corresponding feed ports of the three annular microchannels of the oil bubble generator, and can prepare and generate stable active oil bubbles with a large adjustable size range and an easily controllable oil film thickness, realizing the efficient recovery of low-rank coal clean coal while reducing the dosage of the flotation collector and improving the flotation effect.

[0070] Example 4

[0071] Another specific embodiment of the present invention is as Figures 1-4 shown, and discloses a cold-state active oil bubble flotation method for low-rank coal flotation. On the basis of Example 1, the steps include steps 1 to 3 of Example 1, and also include:

[0072] Step S4: The active oil bubbles generated by the oil bubble generator 1 are inhaled into the flotation column 6 through the air inlet of the bubble generator 5; the bubble generator 5 relies on the negative pressure generated by the high-speed circulation of the coal slurry by the circulation pump 7 to inhale the active oil bubbles, and the active oil bubbles are further pulverized and then mineralized with the circulating pulp.

[0073] Compared with the prior art, for the cold-state active oil bubble flotation method provided in this embodiment, the oil bubble generator includes three annular microchannels and has no heating device. Only relying on the rapid flow and shear of the liquid in the microchannels, it can efficiently generate stable active oil bubbles; the active collector delivery pipeline, the clear water delivery pipeline, and the gas delivery pipeline are respectively connected to the corresponding feeding ports of the three annular microchannels of the oil bubble generator, and can prepare and generate stable active oil bubbles with a large adjustable size range and an easily controllable oil film thickness. While reducing the dosage of the flotation collector, it realizes the efficient recovery of low-rank coal clean coal and improves the flotation effect.

[0074] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention.

Claims

1. A cold-active oil bubble preparation device for low-rank coal flotation, characterized in that It is composed of an active collector delivery pipeline, a clear water delivery pipeline, a gas delivery pipeline and an oil bubble generator (1). The clear water delivery pipeline, the active collector delivery pipeline and the gas delivery pipeline are communicated with the feed inlet of the oil bubble generator (1). The active collector delivery pipeline includes a chemical dosing tank (21) and a mixing tank (22). The chemical dosing tank (21) delivers the surfactant that has been stirred evenly into the mixing tank (22). The mixing tank (22) is used to stir and mix the surfactant and the collector added into it. The oil bubble generator (1) includes a first microchannel (11), a second microchannel (12) and a third microchannel (13) arranged coaxially. The second microchannel (12) is located between the first microchannel (11) and the third microchannel (13). The feed inlets of the first microchannel (11), the second microchannel (12) and the third microchannel (13) are on the same side. The discharge outlets of the first microchannel (11), the second microchannel (12) and the third microchannel (13) are communicated. And the discharge outlets of the second microchannel (12) and the third microchannel (13) are located in the first microchannel (11). The media flowing out of the second microchannel (12) and the third microchannel (13) converge into the first microchannel (11). The clear water delivery pipeline, the active collector delivery pipeline and the gas delivery pipeline are respectively communicated with the feed inlets of the first microchannel (11), the second microchannel (12) and the third microchannel (13). A oil bubble output pipeline (14) is provided at the lower end of the discharge outlet of the first microchannel (11). The media flowing out of the discharge outlets of the first microchannel (11), the second microchannel (12) and the third microchannel (13) enter the oil bubble output pipeline (14), and the formed oil bubbles are discharged from the oil bubble output pipeline (14).

2. The cold-state active oil bubble preparation device for low-rank coal flotation according to claim 1, characterized in that, The feed inlet includes a first feed inlet. The clear water delivery pipeline includes a water storage tank (31). The water storage tank (31) is communicated with the first feed inlet.

3. The cold-state active oil bubble preparation device for low-rank coal flotation according to claim 1, wherein The feed inlet includes a second feed inlet. The mixing tank (22) is communicated with the second feed inlet.

4. The cold-state active oil bubble preparation device for low-rank coal flotation according to claim 1, characterized in that The gas delivery pipeline includes an air compressor (41) and a gas storage tank (42). The air compressor (41) compresses the inhaled dry air and stores it in the gas storage tank (42).

5. The cold-state active oil bubble preparation device for low-rank coal flotation according to claim 4, wherein, The feed inlet includes a third feed inlet. The gas storage tank (42) is communicated with the third feed inlet.

6. A cold-active oil bubble flotation method for low-rank coal flotation, characterized in that, Using the cold-state active oil bubble preparation device according to any one of claims 1-5, the steps include: Step S1: Preparation of active collector, clear water and air; Step S2: Open the solenoid valves in the clear water delivery pipeline, the active collector delivery pipeline and the gas delivery pipeline to make clear water, active collector and dry air enter the oil bubble generator (1); Step S3: Adjust the opening degrees of the flow regulating valves in the active collector delivery pipeline, the clear water delivery pipeline and the gas delivery pipeline until stable active oil bubbles are generated in the oil bubble generator (1); Step S4: The active oil bubbles generated by the oil bubble generator (1) are inhaled into the flotation column (6) through the air inlet of the bubble generator (5); the bubble generator (5) relies on the negative pressure generated by the circulating pump (7) to circulate the coal slurry to inhale the active oil bubbles, and further pulverizes them and mineralizes them with the circulating pulp.

7. The cold-active oil bubble flotation method for low-rank coal flotation according to claim 6, characterized in that, The oil bubble generator (1) is communicated with the air inlet of the bubble generator (5), and the circulating pump (7) is arranged between the flotation column (6) and the bubble generator (5).

8. The cold-active oil bubble flotation method for low-rank coal flotation according to claim 6, characterized in that, In the step S1, after adding the surfactant to the chemical dosing tank (21) and stirring evenly, it is added to the stirring tank (22) through the first peristaltic pump (23) and the first liquid flowmeter (24) and mixed and stirred evenly with the collector.

9. The cold-active oil bubble flotation method for low-rank coal flotation according to any one of claims 6-8, characterized in that, In the step S2, the solenoid valves in the clear water delivery pipeline, the active collector delivery pipeline, and the gas delivery pipeline are opened simultaneously or sequentially.

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