A method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation

Abstract

The present invention belongs to the field of mineral processing technology, and specifically relates to a method for purifying fine-grained flake graphite ore using nanobubbles combined with synchronous ultrasonic flotation. The method comprises: mixing fine-grained flake graphite with water to produce a slurry; inserting an ultrasonic probe into the slurry and turning on an ultrasonic generator; adding a pH adjuster to adjust the slurry pH to 7-10; then sequentially adding an inhibitor, a collector, and a frother; and then using a pressure-dissolved air method to generate nanobubbles. Water and compressed air are introduced into an air dissolving tank to dissolve the air at a pressure of 0.3-0.5 MPa. The air-dissolved water is then released into a flotation tank through a pressure reducing valve to form nanobubbles. Finally, aeration and scraping are performed to flotate the ore into a concentrate. The method can increase the fixed carbon content of fine-grained flake graphite ore to 73% through a single roughing operation, and improve the recovery rate to over 90%.

Description

Technical Field

[0001] The present invention belongs to the technical field of mineral processing, and in particular relates to a method for purifying fine-grained flake graphite ore by combining nanobubbles with synchronous ultrasonic flotation. Background Art

[0002] As a resource of immense strategic value, graphite, with its unique structure and outstanding properties, including thermal and electrical conductivity, lubricity, high-temperature resistance, and chemical stability, has found widespread application in a wide range of fields, including new energy, electronics, healthcare, metallurgy, and aerospace. It has become an indispensable non-metallic material in the development of modern industry and high-tech sectors, and plays an increasingly important role in global economic development.

[0003] With the rapid development of the economy, the demand for graphite continues to increase. Traditional coarse-grained graphite resources are gradually decreasing. Fine-grained graphite has become an important supplement to graphite resources. Making full use of fine-grained graphite resources can alleviate the contradiction between supply and demand of graphite resources and ensure the sustainable development of the industry. In addition, with the continuous mining of graphite, the graphite mines in many places have shown the characteristics of fine and poor mixing, resulting in insufficient dissociation. Therefore, multi-stage grinding is often used to promote dissociation, resulting in the production of a large amount of fine-grained graphite. However, this part of the resources is difficult to purify, resulting in serious waste of resources.

[0004] Existing technology, such as a patented method for efficiently purifying coal-based graphite (publication number: CN115043399A), includes the following steps: (1) electrochemically oxidizing and microwave-heating the coal-based graphite in sequence to obtain expanded microcrystalline graphite; (2) mixing the expanded microcrystalline graphite obtained in step (1) with water and subjecting it to ultrasonic treatment to obtain graphite slurry; (3) subjecting the graphite slurry obtained in step (2) to nanobubble flotation to obtain graphite concentrate. The flotation conditions for nanobubble flotation in step (3) are: aeration volume of 0.5-2.0 L / min, feed rate of 0.5-2.0 L / min, foam layer thickness of 200-500 mm, flushing water flow rate of 0.5-2.0 L / min, and graphite slurry pH of 9-10. This technology can process raw materials with a fixed carbon content of about 80% and can produce products with a fixed carbon content of about 90-97%. Compared with the raw materials, the fixed carbon content in the product is only 1.12-1.25 times that of the raw materials. Summary of the Invention

[0005] Traditional graphite flotation methods often face challenges when processing fine-grained flake graphite. On the one hand, due to its small particle size and large specific surface area, fine-grained flake graphite easily mixes with gangue minerals during flotation, making separation difficult. On the other hand, conventional flotation methods have limited efficiency and selectivity, resulting in low flotation efficiency and low fixed carbon enrichment. The present invention provides a method for purifying fine-grained flake graphite ore using nanobubbles combined with synchronous ultrasonic flotation. This method aims to effectively separate fine-grained flake graphite from gangue minerals, enhance flotation efficiency, and simultaneously improve the fixed carbon recovery rate and significantly increase the fixed carbon content of the concentrate.

[0006] In order to achieve the above-mentioned object of the present invention, the present invention proposes for the first time a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation, which comprises the following steps:

[0007] (1) adding fine flake graphite having a fixed carbon content of 30% or less into a flotation tank and mixing with water at a pulp concentration of 8 wt.% to 20 wt.%, turning on a stirring switch to mix the pulp evenly, and preparing a pulp;

[0008] (2) inserting an ultrasonic probe into the slurry of step (1), turning on an ultrasonic generator for synchronous ultrasonic treatment, and stirring for 3 to 5 minutes;

[0009] (3) adding a pH adjuster to the above slurry to adjust the pH of the slurry to 7-10, and stirring for 2-5 minutes;

[0010] (4) adding an inhibitor in an amount of 700 to 1200 g / t, preferably 800 to 1000 g / t, to the pH-adjusted slurry and stirring for 2 to 5 minutes;

[0011] (5) adding a collector to the slurry to which the inhibitor has been added at a dosage of 260 to 420 g / t, preferably 280 to 380 g / t, more preferably 340 to 360 g / t, and stirring for 2 to 5 minutes;

[0012] (6) Adding a foaming agent in an amount of 150-320 g / t or 150-180 g / t to the slurry to which the collector has been added, and stirring for 1-3 minutes;

[0013] (7) introducing a supersaturated aqueous solution containing air formed by a pressure-dissolved gas method into the slurry to which a foaming agent has been added, and forming nanobubbles in the slurry; when the supersaturated aqueous solution containing air is formed, the pressure of the gas passing through is 0.3 to 0.5 MPa, preferably 0.35 to 0.45 MPa, and more preferably 0.38 to 0.42 MPa;

[0014] (8) Under ultrasonic conditions, a supersaturated aqueous solution containing dissolved air is introduced while air is filled in, and the foam is scraped for 4 to 7 minutes. The foam scraped out is filtered and dried to obtain flake graphite concentrate, and the rest is tailings; the amount of air filled is 40 to 80 L / h.

[0015] The present invention can process micro-grained flake graphite ores with ultra-low fixed carbon content, such as micro-grained flake graphite ores with a fixed carbon content of 20% or less, and of course also micro-grained flake graphite ores with a fixed carbon content of 5% to 18%.

[0016] As a preferred embodiment, the present invention provides a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation.

[0017] The micro-grained flake graphite has a particle size of -300 mesh and accounts for more than 80%.

[0018] As a preferred embodiment, the present invention provides a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation.

[0019] The stirring process is carried out by using a flotation machine impeller with a rotation speed of 1200 to 1900 r / min, preferably 1500 to 1700 r / min. The present invention controls the stirring speed to 1200 to 1900 r / min. In the stage of adding flotation reagents, it mainly plays the role of uniform reagents. When introducing a supersaturated aqueous solution containing dissolved air, it is conducive to the formation of more and smaller nanobubbles. In combination with subsequent ultrasound, the number of nanobubbles is further increased, thereby significantly improving the flotation effect, especially the enrichment effect of fixed carbon. If the rotation speed is too low, the nanobubbles may not be fully dispersed into the slurry, affecting their contact with mineral particles, and may make solid particles in the slurry easily precipitate, affecting the flotation process; if the rotation speed is too high, the stability of the nanobubbles may be destroyed, causing them to rupture or merge prematurely, thereby reducing the role of the nanobubbles in flotation. At the same time, too high a rotation speed may cause impurities to be entrained in the bubbles, thereby reducing the fixed carbon content of the concentrate.

[0020] Preferably, in the method of the present invention for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation, the frequency of the ultrasound used is 18-25KHz, preferably 20KHz, and the power is set to 80-200W, preferably 135-165W.

[0021] Preferably, the present invention provides a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation.

[0022] The pH adjusters used are HCl and NaOH. The pH of the slurry is controlled to be 7 to 10, preferably 7.5 to 8.5.

[0023] Preferably, the present invention provides a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation.

[0024] The inhibitor used is one of water glass, sodium hexametaphosphate, and sodium carboxymethyl cellulose. Preferably, it is water glass or a mixture of water glass and at least one of sodium hexametaphosphate and sodium carboxymethyl cellulose.

[0025] In the present invention, water glass is used as an inhibitor primarily because silicate ions can adsorb on the surface of gangue minerals under certain conditions, forming a hydrophilic film that prevents them from interacting with collectors. The range in which silicate ions exert their effect is generally around 8 to 11. If the pH is too low, the water glass will not be sufficiently hydrolyzed, the concentration of silicate ions will be low, and the inhibitory effect will be insignificant. Excessively high pH may cause changes in the surface charge of the minerals, affecting the adsorption of silicate ions. Due to the different properties of the ores, different pH values ​​will result in different flotation effects. This specific pH is generally determined through experiments in actual situations. Experiments have found that the pH range of 7 to 10 is the best, so the pH range is limited to 7 to 10, and more preferably 7.5 to 8.5.

[0026] Preferably, the present invention provides a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation.

[0027] The collector used is one of kerosene, diesel and liquid paraffin.

[0028] Preferably, the present invention provides a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation.

[0029] The foaming agent used is one of pine oil, sec-octanol and methyl isobutyl carbinol.

[0030] Preferably, the present invention provides a method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation.

[0031] The supersaturated aqueous solution containing dissolved air is prepared by the pressure-dissolved air method as follows: first, water and compressed air are introduced into an air dissolution tank. A booster pump is used to raise the pressure to 0.3-0.5 MPa, preferably 0.35-0.45 MPa, and more preferably 0.38-0.42 MPa. At this pressure, the air gradually dissolves in the water, forming a supersaturated solution. In practical applications, the air-dissolved water is slowly released into a flotation tank through a pressure-reducing valve. As the pressure decreases, the dissolved air rapidly forms nanobubbles. The size and number of the nanobubbles can be controlled by adjusting the opening of the pressure-reducing valve and the release rate, thereby achieving the desired effect of introducing nanobubbles into the flotation process.

[0032] In step 8 of the present invention, there are no strict requirements on the pressure of the air filled. In actual application, after turning on the inflation switch, the air in the nature is introduced through the flotation machine. During flotation, when the water level in the flotation tank is too high, the pulp will overflow, and when the water level is too low, the automatic bubble scraping plate cannot scrape the foam. Therefore, the height of the pulp in the flotation process has a range. During the continuous flotation process, the liquid level drops due to the scraping of bubbles. At this time, it is necessary to add water slowly and continuously. The present invention uses a supersaturated aqueous solution containing dissolved air instead of the supplemented water. Therefore, the amount of water added here depends on the specific situation in the flotation. It is added slowly and will not exceed the mouth of the flotation tank. It is also within the scraping range of the bubble scraping plate. In general, it is to add slowly to keep the pulp level within a water level line range.

[0033] The present invention can achieve a fixed carbon content of 70-73% in the graphite concentrate obtained by roughing, with a recovery rate of greater than or equal to 88%. After the graphite concentrate obtained by roughing is subjected to at least two rounds of cleaning, the fixed carbon content is greater than or equal to 93%.

[0034] The reagent system for the graphite concentrate obtained by roughing is: inhibitor 440-560g / t, collector 175-205g / t, foaming agent 70-95g / t. More preferably:

[0035] The reagent system for selecting the graphite concentrate obtained by roughing is: inhibitor water glass 450g / t, collector kerosene 175g / t, foaming agent terpineol 80g / t; or inhibitor sodium carboxymethyl cellulose 500g / t, collector diesel 180g / t, foaming agent methyl isobutyl carbinol 75g / t; or

[0036] Inhibitor: water glass 550g / t, collector: kerosene 200g / t, foaming agent: octanol 90g / t.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention uses the synergistic effect of nanobubbles and ultrasound to effectively separate fine-grained flake graphite from gangue minerals, significantly increasing the fixed carbon content of graphite concentrate to meet the needs of high-end application fields; at the same time, nanobubbles increase the probability of attachment of mineral particles to bubbles, and ultrasound promotes the interaction between reagents and minerals and the dispersion of particles. The combined effect of the two greatly improves flotation efficiency and reduces flotation time and reagent dosage; moreover, this method is particularly suitable for the purification of fine-grained flake graphite, solving the difficulties encountered by traditional flotation methods in processing fine-grained minerals and providing a feasible technical solution for the efficient utilization of fine-grained mineral resources; compared with traditional methods, this method reduces the amount of reagents used to a certain extent and reduces pollution to the environment. At the same time, the energy required for ultrasonic treatment is relatively low, which has the advantage of energy saving. In addition to the above advantages, the present invention can process raw materials with low fixed carbon content and achieve efficient enrichment. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The flowchart of a specific embodiment of the present invention is shown in FIG.

[0040] Figure 2 These are electron microscope images of the raw material and the selected product in Example 1, where (a) is a backscattered image of the raw material at 3000 times magnification, and (b) is a backscattered image of the selected concentrate at 3000 times magnification.

[0041] from Figure 1 The basic process of the present invention can be seen in FIG.

[0042] Figure 2 In the graphite, the black part is graphite, and the bright white part is impurity elements such as aluminum and silicon. Figure 2 (a) It can be seen that the raw material particle size is mostly 5-20um, which is fine-grained flake graphite, and the white part accounts for the majority, indicating that the raw material has a low fixed carbon content and a high impurity content. Figure 2 (b) It can be seen that there are only a few bright white particles in the graphite concentrate after selection. Figure 2 (a) In contrast, the impurity content is greatly reduced, indicating that the method provided by the present invention can effectively purify fine-grained graphite. DETAILED DESCRIPTION

[0043] The following examples describe embodiments of the present invention in detail. However, those skilled in the art will appreciate that the following examples are intended to illustrate the present invention only and should not be construed as limiting its scope. Where specific conditions are not specified in the examples, conventional conditions or those recommended by the manufacturer were used. Reagents and instruments used without manufacturer identification are commercially available conventional products.

[0044] In this embodiment, the fixed carbon content of the graphite concentrate obtained in step (8) can reach 72.93%, and the recovery rate can reach 90.26%.

[0045] The specific embodiments of the present invention are further described below in conjunction with examples, but the present invention is not limited to the scope of the examples.

[0046] Example 1

[0047] The XRD test results of the fine-grained natural flake graphite ore produced in the Xinjiang mining area show that the impurities are mainly mica, quartz and feldspar. Its composition is shown in Table 1.

[0048] Table 1 Composition of natural flake graphite from a mining area in Xinjiang

[0049]

[0050] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0051] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1600 r / min to mix the pulp evenly to prepare a pulp;

[0052] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at 1600 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1600 rpm for 2 minutes.

[0053] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1600 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0054] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 72.93% and a recovery rate of 89.71%.

[0055] The graphite concentrate obtained from the roughing was refined in the presence of 450 g / t of water glass as an inhibitor, 175 g / t of kerosene as a collector, and 80 g / t of terpineol as a foaming agent. After three refinements, the fixed carbon content in the graphite concentrate increased to 95.13%.

[0056] Example 1-1

[0057] Other conditions are the same as those in Example 1, except that when generating nanobubbles, the booster pump pressure is 0.3 MPa, that is:

[0058] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.3 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0059] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1600 r / min to mix the pulp evenly to prepare a pulp;

[0060] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at 1600 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1600 rpm for 2 minutes.

[0061] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1600 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0062] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 71.80% and a recovery rate of 85.36%.

[0063] The graphite concentrate obtained by roughing is refined in the presence of 450g / t of water glass as an inhibitor, 175g / t of kerosene as a collector, and 80g / t of terpineol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 94.74%.

[0064] Example 1-2

[0065] Other conditions are the same as those in Example 1, except that when generating nanobubbles, the booster pump pressure is 0.5 MPa, that is:

[0066] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.5 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0067] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1600 r / min to mix the pulp evenly to prepare a pulp;

[0068] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at 1600 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1600 rpm for 2 minutes.

[0069] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1600 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0070] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 68.89% and a recovery rate of 88.01%.

[0071] The graphite concentrate obtained from the roughing was refined in the presence of 450 g / t of water glass as an inhibitor, 175 g / t of kerosene as a collector, and 80 g / t of terpineol as a foaming agent. After three refinements, the fixed carbon content in the graphite concentrate increased to 94.15%.

[0072] Examples 1-3

[0073] Other conditions were the same as those in Example 1, except that the inhibitor dosage was 1200 g / t, i.e.:

[0074] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0075] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1600 r / min to mix the pulp evenly to prepare a pulp;

[0076] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at a speed of 1600 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 1200 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at a speed of 1600 rpm for 2 minutes.

[0077] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1600 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0078] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 70.66% and a recovery rate of 87.95%.

[0079] The graphite concentrate obtained by roughing is refined in the presence of 450g / t of water glass as an inhibitor, 175g / t of kerosene as a collector, and 80g / t of terpineol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 94.90%.

[0080] Examples 1-4

[0081] Other conditions are the same as those in Example 1, except that the amount of collector is 280 g / t, that is:

[0082] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0083] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1600 r / min to mix the pulp evenly to prepare a pulp;

[0084] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at 1600 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 280 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1600 rpm for 2 minutes.

[0085] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1600 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0086] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 72.01% and a recovery rate of 82.16%.

[0087] The graphite concentrate obtained from the roughing was refined in the presence of 450 g / t of water glass as an inhibitor, 175 g / t of kerosene as a collector, and 80 g / t of terpineol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate increased to 94.93%.

[0088] Examples 1-5

[0089] Other conditions are the same as those in Example 1, except that the amount of foaming agent is 320 g / t, that is:

[0090] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0091] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1600 r / min to mix the pulp evenly to prepare a pulp;

[0092] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at 1600 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 320 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1600 rpm for 2 minutes.

[0093] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1600 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0094] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 65.17% and a recovery rate of 87.64%.

[0095] The graphite concentrate obtained by roughing is refined in the presence of 450g / t of water glass as an inhibitor, 175g / t of kerosene as a collector, and 80g / t of terpineol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 93.99%.

[0096] Examples 1-6

[0097] Other conditions are the same as those in Example 1, except that the speed is adjusted to 1200 r / min and the air intake volume is controlled to 40 L / h, that is:

[0098] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0099] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1200 r / min to mix the pulp evenly to prepare a pulp;

[0100] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at 1200 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1200 rpm for 2 minutes.

[0101] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1200 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 40 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0102] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 68.51% and a recovery rate of 88.04%.

[0103] The graphite concentrate obtained from the roughing was refined in the presence of 450 g / t of water glass as an inhibitor, 175 g / t of kerosene as a collector, and 80 g / t of terpineol as a foaming agent. After three refinements, the fixed carbon content in the graphite concentrate increased to 93.42%.

[0104] Examples 1-7

[0105] Other conditions are the same as those in Example 1, except that the speed is adjusted to 1900 r / min and the air intake volume is controlled to 80 L / h, that is:

[0106] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0107] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1900 r / min to mix the pulp evenly to prepare a pulp;

[0108] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring at 1900 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1900 rpm for 2 minutes.

[0109] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1900 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 80 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0110] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 66.82% and a recovery rate of 90.03%.

[0111] The graphite concentrate obtained by roughing is refined in the presence of 450g / t of water glass as an inhibitor, 175g / t of kerosene as a collector, and 80g / t of terpineol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 93.77%.

[0112] Examples 1-8

[0113] Other conditions were the same as those in Example 1, except that the ultrasonic power was 200 W, the rotation speed was 1500 r / min, and the pH was adjusted to 9, that is:

[0114] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0115] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1500 r / min to mix the pulp evenly to prepare a pulp;

[0116] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 200W. After stirring at 1500 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 9. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and stirring was continued at 1500 rpm for 2 minutes.

[0117] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1500 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0118] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 64.27% and a recovery rate of 87.14%.

[0119] The graphite concentrate obtained by roughing is refined in the presence of 450g / t of water glass as an inhibitor, 175g / t of kerosene as a collector, and 80g / t of terpineol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 94.67%.

[0120] Examples 1-9

[0121] Other conditions were the same as those in Example 1, except that the ultrasonic power was 80 W, the rotation speed was 1500 r / min, and the pH was adjusted to 10, that is:

[0122] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0123] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a pulp concentration of 15%, and the stirring switch is turned on at a speed of 1500 r / min to mix the pulp evenly to prepare a pulp;

[0124] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 80W. After stirring at 1500 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 10. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added, and the mixture was stirred at 1500 rpm for 2 minutes.

[0125] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1500 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 60 L / h, and then scraping is performed for 5 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0126] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 65.21% and a recovery rate of 51.37%.

[0127] The graphite concentrate obtained by roughing is refined in the presence of 450g / t of water glass as an inhibitor, 175g / t of kerosene as a collector, and 80g / t of terpineol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 87.92%.

[0128] Example 2

[0129] The XRD test results of fine-grained natural flake graphite produced in a mining area in Henan Province show that the impurities are mainly mica, quartz, feldspar and pyrite. Its composition is shown in Table 2.

[0130] Table 2 Composition of natural flake graphite from a mining area in Henan

[0131]

[0132] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.3 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0133] The fine-grained natural flake graphite produced in Henan Province is mixed with water at a ratio of 20% of the slurry concentration, and the stirring switch is turned on at a speed of 1400 r / min to mix the slurry evenly to prepare the slurry;

[0134] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 160W. After stirring at a speed of 1400 rpm for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, an inhibitor, sodium carboxymethyl cellulose, was added at a dosage of 1000 g / t. After stirring for 3 minutes, a collector, diesel, was added at a dosage of 360 g / t. After stirring for 3 minutes, a foaming agent, methyl isobutyl carbinol, was added at a dosage of 150 g / t. The mixture was stirred at a speed of 1400 rpm for 2 minutes.

[0135] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to quickly form nanobubbles, thereby introducing nanobubbles. After continuing to stir at a speed of 1400 rpm for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 40 L / h, and then scraping is performed for 6 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can also scrape the foam well. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0136] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 70.64% and a recovery rate of 88.71%.

[0137] The graphite concentrate obtained by roughing is refined in the presence of 500 g / t of sodium carboxymethyl cellulose as an inhibitor, 180 g / t of diesel as a collector, and 75 g / t of methyl isobutyl carbinol as a foaming agent. After four refinements, the fixed carbon content in the graphite concentrate is increased to 94.98%.

[0138] Example 3

[0139] The XRD test results of natural flake graphite produced in a mining area in Heilongjiang Province show that the impurities are mainly mica and quartz. Its composition is shown in Table 3.

[0140] Table 3 Composition of natural flake graphite from a mining area in Heilongjiang

[0141]

[0142] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.5 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0143] The fine-grained natural flake graphite produced in Heilongjiang is mixed with water at a pulp concentration of 12%, and a stirring switch is turned on at a speed of 1500 r / min to uniformly mix the pulp to prepare a pulp;

[0144] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring for 4 minutes, a pH adjuster was added to adjust the slurry pH to 9. After stirring for 3 minutes, 1100 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 400 g / t of kerosene as a collector was added. After stirring for 3 minutes, 180 g / t of sec-octanol as a foaming agent was added and stirred for 2 minutes.

[0145] The supersaturated solution containing air prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced to allow the air dissolved in the water to rapidly form nanobubbles, thereby introducing nanobubbles. After stirring for 1 minute, the aeration switch is turned on (at this time, ultrasound is continuously applied and a supersaturated solution containing air is introduced), the air intake rate is controlled at 80 L / h, and then scraping is performed for 6 minutes. During the scraping process, the air is continuously introduced until no foam is scraped off, at which point flotation and aeration are terminated. During the scraping process, the supersaturated solution containing air is continuously and slowly introduced to keep the pulp height within a range within which the pulp will not overflow and the scraper can effectively scrape the foam. The scraped foam is filtered and dried at 105°C to obtain flake graphite concentrate.

[0146] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 70.98% and a recovery rate of 90.26%.

[0147] The graphite concentrate obtained by roughing is refined in the presence of 550 g / t of water glass as an inhibitor, 200 g / t of kerosene as a collector, and 90 g / t of octanol as a foaming agent. After three rounds of refinement, the fixed carbon content in the graphite concentrate is increased to 93.72%.

[0148] Comparative Example 1

[0149] Other conditions are the same as those in the roughing process of Example 1, except that no ultrasonic treatment is performed; that is:

[0150] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.4 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution containing dissolved air;

[0151] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a ratio of 15% of the slurry concentration, and the stirring switch is turned on and the speed is 1600 r / min (the stirring speed mentioned below is 1600 r / min) to mix the slurry evenly to prepare the slurry;

[0152] After stirring for 4 minutes, add pH adjuster to adjust the pH of the pulp to 8. After stirring for 3 minutes, add 900g / t of water glass as an inhibitor. After stirring for 3 minutes, add 350g / t of kerosene as a collector. After stirring for 3 minutes, add 160g / t of pine oil as a foaming agent and stir for 2 minutes.

[0153] The air-dissolved water prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced, causing the dissolved air in the water to rapidly form nanobubbles, thereby introducing the nanobubbles. Stirring is continued for 1 minute, and then the aeration switch is turned on. The flakes are then scraped for 5 minutes. The scraped foam is then filtered and dried at 105°C to obtain flake graphite concentrate.

[0154] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 57.04% and a recovery rate of 43.27%.

[0155] Comparative Example 2

[0156] Other conditions are the same as those in the roughing process of Example 1, except that nanobubbles are not introduced; that is:

[0157] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a ratio of 15% of the slurry concentration, and the stirring switch is turned on and the speed is 1600 r / min (the stirring speed mentioned below is 1600 r / min) to mix the slurry evenly to prepare the slurry;

[0158] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150 W. After stirring for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, an inhibitor, water glass, was added at a dosage of 900 g / t. After stirring for 3 minutes, a collector, kerosene, was added at a dosage of 350 g / t. After stirring for 3 minutes, a foaming agent, pine alcohol, was added at a dosage of 160 g / t. After stirring for 3 minutes, the aeration switch was turned on, and then scraping and foaming were performed for 5 minutes. The scraped foam was filtered and dried at 105° C. to obtain flake graphite concentrate.

[0159] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 60.29% and a recovery rate of 62.83%.

[0160] Comparative Example 3

[0161] Other conditions were the same as those in the roughing process of Example 1, except that no simultaneous ultrasonic treatment was performed and no nanobubbles were introduced; that is:

[0162] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a ratio of 15% of the slurry concentration, and the stirring switch is turned on and the speed is 1600 r / min (the stirring speed mentioned below is 1600 r / min) to mix the slurry evenly to prepare the slurry;

[0163] After stirring for 4 minutes, a pH adjuster was added to adjust the pH of the pulp to 8. After stirring for 3 minutes, 900 g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350 g / t of kerosene as a collector was added. After stirring for 3 minutes, 160 g / t of pine oil as a foaming agent was added. After stirring for 3 minutes, the aeration switch was turned on, and the mixture was scraped for 5 minutes. The scraped foam was filtered and dried at 105°C to obtain flake graphite concentrate.

[0164] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 49.77% and a recovery rate of 29.96%.

[0165] Comparative Example 4

[0166] Other conditions are consistent with the roughing process in Example 2, except that when generating nanobubbles, the booster pump pressure is not within the protection range of 0.3-0.5 MPa of the present invention, that is:

[0167] First, water and compressed air are introduced into the air dissolving tank, and the pressure is increased to 0.7 MPa by a booster pump, so that the air gradually dissolves in the water to form a supersaturated solution;

[0168] The fine-grained natural flake graphite produced in Xinjiang is mixed with water at a ratio of 15% of the slurry concentration, and the stirring switch is turned on and the speed is 1600 r / min (the stirring speed mentioned below is 1600 r / min) to mix the slurry evenly to prepare the slurry;

[0169] Then, an ultrasonic probe was inserted into the slurry, and the ultrasonic generator was turned on for synchronous ultrasonic treatment. The ultrasonic power was set to 150W. After stirring for 4 minutes, a pH adjuster was added to adjust the slurry pH to 8. After stirring for 3 minutes, 900g / t of water glass as an inhibitor was added. After stirring for 3 minutes, 350g / t of kerosene as a collector was added. After stirring for 3 minutes, 160g / t of pine oil as a foaming agent was added and stirred for 2 minutes.

[0170] The air-dissolved water prepared above is then slowly released into the flotation tank through a pressure reducing valve. The pressure is then reduced, causing the dissolved air in the water to rapidly form nanobubbles, thereby introducing the nanobubbles. Stirring is continued for 1 minute, and then the aeration switch is turned on. The flakes are then scraped for 5 minutes. The scraped foam is then filtered and dried at 105°C to obtain flake graphite concentrate.

[0171] During the flotation process, natural flake graphite ore was flotated at room temperature. The flotation product obtained through continuous expansion tests showed a fixed carbon content of 65.09% and a recovery rate of 83.71%.

Claims

1. A method for purifying fine-grained flake graphite ore using nanobubbles combined with synchronous ultrasonic flotation, characterized in that: The following steps are involved: (1) Add fine flake graphite with a fixed carbon content of 30% or less into a flotation tank and mix it with water at a pulp concentration of 8wt.% to 20wt.%, turn on the stirring switch to mix the pulp evenly, and prepare pulp; (2) inserting an ultrasonic probe into the slurry described in step (1), turning on the ultrasonic generator for synchronous ultrasonic treatment, and stirring for 3 to 5 minutes; (3) Add a pH adjuster to the above slurry to adjust the pH of the slurry to 7-10, and stir for 2-5 minutes; (4) Add an inhibitor at a dosage of 700-1200 g / t to the pH-adjusted slurry and stir for 2-5 minutes; (5) Add a collector at a dosage of 260-420 g / t to the slurry containing the inhibitor and stir for 2-5 minutes; (6) Add a foaming agent at a dosage of 150-320 g / t to the slurry to which the collector has been added, and stir for 1-3 minutes; (7) introducing a supersaturated aqueous solution containing air formed by a pressure-dissolved gas method into the slurry to which a foaming agent has been added, thereby forming nanobubbles in the slurry; when the supersaturated aqueous solution containing air is formed, the pressure of the gas passing through is 0.3 to 0.5 MPa; The preparation method of the supersaturated aqueous solution containing dissolved air formed by the pressure dissolved air method is as follows: first, water and compressed air are introduced into the dissolved air tank, and the pressure is increased to 0.3-0.5 MPa by a booster pump; (8) Under ultrasonic conditions, while introducing a supersaturated aqueous solution containing dissolved air, air is added and scraping is performed for 4 to 7 minutes. The scraped foam is filtered and dried to obtain flake graphite concentrate, and the rest is tailings; the air filling rate is 40 to 80 L / h; The fixed carbon content of the graphite concentrate obtained from roughing is 70-73%, and the recovery rate is greater than or equal to 88%. After at least two rounds of cleaning, the fixed carbon content of the graphite concentrate obtained from roughing is greater than or equal to 93%. The reagent system for selecting graphite concentrate obtained from roughing is: inhibitor 440~560g / t, collector 175~205g / t, foaming agent 70~95g / t.

2. The method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation according to claim 1, characterized in that: The fixed carbon content in the fine-grained flake graphite is less than or equal to 20%.

3. The method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation according to claim 1, characterized in that: The particle size of the fine-grained flake graphite is -300 mesh, accounting for more than 80%.

4. The method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation according to claim 1, characterized in that: The stirring process is carried out by using a flotation machine impeller with a rotation speed of 1200-1900 r / min.

5. The method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation according to claim 1, characterized in that: The frequency of the ultrasound used is 18~25KHz, and the power is set to 80~200W.

6. The method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation according to claim 1, characterized in that: The pH adjusters used were HCl and NaOH; Control the pH of the slurry to 7-10.

7. The method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation according to claim 1, characterized in that: The inhibitor used is one of water glass, sodium hexametaphosphate and sodium carboxymethyl cellulose.

8. The method for purifying fine-grained flake graphite ore by nanobubble combined with synchronous ultrasonic flotation according to claim 1, characterized in that: The collector used is one of kerosene, diesel and liquid paraffin; The foaming agent used is one of pine oil, sec-octanol and methyl isobutyl carbinol.

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