Device and method for grading coal gasification fine slag

Abstract

The invention discloses a device for grading coal gasification fine slag, which belongs to the field of solid waste treatment and comprises a solid-liquid blending device, a coal gasification fine slag grading device and a coal gasification fine slag grading device. The flotation device is connected with a discharge hole of the solid-liquid blending device; the foam collecting device is arranged behind the flotation device; the screening device is communicated with the discharging end of the foam collecting device; the invention further discloses a coal gasification fine slag quality grading method. The device and the method have the beneficial effects that the coal gasification fine slag is classified according to the quality, so that the operation steps of settling, filtering, drying and the like on fine slag suspension liquid in a coal gasification process are omitted, the coal gasification fine slag is classified more finely according to the quality, and the utilization value, the economic benefit and the environmental benefit of the coal gasification fine slag are improved.

Description

Technical Field

[0001] The invention relates to the field of solid waste treatment, and in particular to a device and method for quality classification of coal gasification fine slag. Background Art

[0002] Coal gasification slag is a solid waste produced during the coal gasification process. my country produces more than 80 million tons of it every year. Currently, coal gasification slag is mainly treated by stacking and landfilling. This not only occupies a large amount of land resources, but also causes serious pollution to the ecological environment. Coal gasification slag is mainly composed of residual carbon and ash. If these two components can be effectively separated, they will have important environmental and economic value. Flotation is a method for efficiently separating coal gasification slag. However, the flotation separation method has the problem of low efficiency in treating coal gasification slag, especially small-sized ash particles are easily entrained into the concentrate, which seriously affects the separation effect and product quality.

[0003] To this end, we propose a device and method for classifying fine slag from coal gasification. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the present invention provides a device and method for classifying coal gasification fine slag.

[0005] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is:

[0006] A device for grading fine slag from coal gasification comprises: a solid-liquid blending device, a shell body of which is provided with a feed inlet and a discharge outlet, the solid-liquid blending device being used for proportioning and concentrating the fine slag suspension produced in the coal gasification process section; a flotation device connected to the discharge outlet of the solid-liquid blending device, the flotation device being used for flotation of the fine slag suspension concentrated by the solid-liquid blending device; a foam collecting device, arranged behind the flotation device, the foam collecting device being used for receiving a foam layer after flotation by the flotation device; a screening device, connected to the discharge end of the foam collecting device, the screening device being used for vibrating, screening and grading the foam layer collected by the foam collecting device.

[0007] By setting up a solid-liquid blending device, the fine slag suspension generated in the coal gasification process section is proportioned and concentrated, and then floated by a flotation device to obtain tailings and a foam layer, and then the foam layer is collected by a foam collecting device, and then the foam layer is sent to a screening device for vibration screening to obtain a concentrate. Compared with the prior art in which the fine slag suspension is sedimented, filtered, and other steps to obtain solid waste coal gasification fine slag, which is generally treated by stacking and landfilling, different carbon-rich products are obtained after treatment by this device, and different carbon-rich products can be used for different purposes, thereby realizing the recycling of coal gasification fine slag, and there is no need to sediment and filter the fine slag suspension before treatment, so the recovered products are more diverse and the product uses are wider.

[0008] It is further defined that the solid-liquid mixing device includes a hollow shell, a mixing rake, a mixing shaft and an overflow hole; the space inside the shell serves as a mixing bin, the mixing shaft is vertically rotatably connected to the shell, and the mixing shaft is located at the center of the shell, the mixing rake is fixed on the circumferential surface of the mixing shaft, the mixing shaft is driven to rotate by a motor, a feed pipe is provided at the feed port, the feed port is opened at the upper part of the side wall of the shell, the shell is cylindrical, and the bottom surface is a downwardly protruding conical surface, the discharge port is opened at the center of the bottom surface of the shell, the discharge port is connected to the discharge pipe, the overflow hole is opened at the upper part of the side wall of the shell, and the overflow hole is connected to the overflow pipe.

[0009] Fine slag suspension is added into the batching bin through the feed port. The internal batching rake drives the solid particles at the bottom to move under the rotation of the batching shaft to prevent the solid particles from settling at the bottom. Under the action of gravity sedimentation and the batching rake, flotation slurry with a suitable flotation solid-liquid ratio is obtained. The flotation slurry is discharged from the discharge pipe of the discharge port. The obtained water density is lower than that of the flotation slurry and is discharged from the overflow pipe on the top of the batching bin. The water can also be used for gas washing in the coal gasification process section, which is more conducive to material saving.

[0010] It is further defined that the flotation device includes a flotation tank, a ventilation pipe, a tailings outlet, a flotation motor, a flotation rotor and a scraper; the end of the discharge pipe is located in the flotation tank, a discharge slot is provided on one side of the flotation tank, the flotation motor is vertically fixed above the flotation tank through a bracket, the flotation rotor is fixedly connected to the output shaft of the flotation motor, the ventilation pipe is passed through the outside of the flotation rotor and the top is fixed on the bracket, an air intake pipe connected to an air intake device is provided on the circumference of the ventilation pipe, the tailings outlet is opened at the bottom of the flotation tank, and the scraper is provided above the flotation tank through a rotating shaft, and is used to scrape the foam layer on the surface of the flotation tank out of the discharge slot.

[0011] The flotation pulp is discharged into the flotation tank for flotation. The ash in the flotation pulp is generally hydrophilic, and the residual carbon is hydrophobic. The hydrophobic residual carbon gradually forms bubbles under the action of air and flotation agents and floats to the top to form a bubble layer, while the ash forms a pulp layer at the bottom. The pulp layer is discharged from the tailings outlet at the bottom of the flotation tank. The discharged pulp layer is sedimented and filtered to obtain tailings, thereby realizing the separation and recovery of residual carbon.

[0012] It is further defined that the foam collecting device is in the shape of a disk, and the bottom surface is a downwardly protruding conical surface, the foam collecting device is arranged below the discharge slot to access the foam layer, and a trumpet-shaped discharge outlet is provided at the center of the bottom surface of the foam collecting device, and the discharge outlet is connected to a discharge pipe, and the foam collecting device is connected to the screening device through the discharge pipe; the foam collecting device is arranged in a disk-shaped structure, which is simple, and is arranged below the discharge slot to directly access the bubble layer, which is easy to use.

[0013] It is further defined that the screening device includes a screening body, a screening inlet, a screen box cover, an observation port, a screen and a receiving hopper; the screen box cover is arranged above the screening body to close the screening body, the screen is arranged obliquely in the screening body, the screening inlet and the observation port are both arranged on the screen box cover, the screen box cover is also arranged obliquely, and the screening inlet is arranged at the highest point of the screen box cover, the receiving hopper matches the screen, is arranged obliquely below the screen, and the discharge pipe is connected to the screening inlet; the foam layer is vibrated and screened by the screening body, and the foam that does not pass through the screen is discharged. The one marked as primary concentrate and the one that falls through the screen into the receiving hopper below is marked as secondary concentrate. The foam layer is further screened by a vibration mechanism. The two can be used for different purposes. The primary concentrate has a large specific surface area, a well-developed microscopic pore size and a high carbon content, and can be used for the research of carbon materials, such as catalyst carriers, electrode materials and adsorbents. Compared with the primary concentrate, the secondary concentrate has a smaller specific surface area and a lower carbon content, and can be returned to the furnace for combustion, reducing coal consumption and improving the utilization rate of coal gasification fine slag and the economic benefits.

[0014] A method for classifying coal gasification fine slag, using the above-mentioned device for classifying coal gasification fine slag, comprises the following steps:

[0015] S1. The fine slag suspension produced by the coal gasification process section is directly transported from the feed port to the mixing bin, and the motor of the solid-liquid mixing device is turned on to drive the mixing rake to rotate, so that the solid particles deposited on the bottom of the pool are pushed into the liquid to mix them into flotation pulp. After the flotation pulp reaches the solid-liquid ratio that meets the flotation requirements, the flotation pulp is discharged from the discharge port;

[0016] S2. After receiving the flotation pulp discharged from the discharge pipe, the flotation device adds flotation reagents into the flotation tank. When the flotation pulp reaches a certain height in the flotation tank, the flotation motor and the air intake device are turned on. At the same time, the motor driving the scraper needs to be turned on. The air intake device transports air into the flotation tank through the air intake pipe and the ventilation pipe. Under the action of air and flotation reagents, the hydrophobic residual carbon forms bubbles and floats to the upper part of the flotation tank to form a foam layer. The ash-rich pulp layer is located at the lower part of the flotation tank. The pulp layer is discharged through the tailings outlet, and tailings are obtained after sedimentation and filtration. The foam layer is scraped into the foam collection device by the scraper;

[0017] S3. After collecting enough foam layer, the foam collecting device transports the foam layer into the screening body through the screening inlet, turns on the motor of the screening body for vibration screening, and the ore that passes through the screen and falls into the receiving hopper is the secondary concentrate, and the ore that does not pass through the screen is the primary concentrate.

[0018] Through this method, the original fine slag suspension is directly subjected to solid-liquid blending, flotation and vibration screening treatment, which saves the pre-treatment steps compared to the existing method of first sedimentation, filtration and then treatment, and the mixed fine slag suspension is separated into tailings rich in inorganic ash, carbon-rich primary concentrate and secondary concentrate through the treatment of this method. Compared with the existing coal gasification fine slag treatment technology, the separation is more refined, and the tailings, primary concentrate and secondary concentrate can all be used for different purposes, thereby improving the recovery rate and economic benefits of coal gasification fine slag and realizing the quality classification of coal gasification fine slag.

[0019] It is further defined that the solid-to-liquid ratio of the flotation slurry in step S1 is 50 kg / m 3 .

[0020] It is further defined that the flotation agent in step S2 is non-polar hydrocarbon oil, and the dosage is 5-25 kg / t.

[0021] It is further defined that the flotation motor speed in step S2 is 1500-2000 rpm and the air flow rate is 0.2-5 m 3 / h.

[0022] The beneficial effects of the present invention are as follows: by using the device and method to classify the coal gasification fine slag, not only the sedimentation, filtration, drying and other operating steps of the fine slag suspension in the coal gasification process are saved, but also the classification is made more refined, thereby improving the utilization value, economic benefits and environmental benefits of the coal gasification fine slag. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 An overall schematic diagram of the device of the present invention;

[0024] Figure 2 It is a schematic diagram of the internal structure of the solid-liquid proportioning device;

[0025] Figure 3 It is a schematic diagram of the internal structure of the flotation device;

[0026] Figure 4 Schematic diagram of the internal structure of the foam collection device and the screening device.

[0027] The symbols of the components are as follows:

[0028] Solid-liquid mixing device 1, shell 11, batching rake 12, batching shaft 13, overflow hole 14, feed port 15, discharge port 16, feed pipe 17, discharge pipe 18, flotation device 2, flotation tank 21, ventilation pipe 22, air inlet pipe 221, tailings outlet 23, flotation motor 24, flotation rotor 25, scraper 26, foam collecting device 3, discharge port 31, discharge pipe 32, screening device 4, screening body 41, screening inlet 42, screen box cover 43, observation port 44, screen 45, receiving hopper 46. DETAILED DESCRIPTION

[0029] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0030] Example:

[0031] like Figure 1-Figure 4As shown, a device for classifying fine slag from coal gasification comprises a solid-liquid mixing device 1, a flotation device 2, a foam collecting device 3 and a screening device 4; the solid-liquid mixing device 1 comprises a hollow shell 11, a batching rake 12, a batching shaft 13 and an overflow hole 14; a feed port 15 and a discharge port 16 are provided on the shell 11, and the solid-liquid mixing device 1 is used to mix and concentrate the fine slag suspension produced in the coal gasification process section; the space inside the shell 11 is used as a mixing bin, the batching shaft 13 is vertically rotatably connected to the shell 11, and the batching shaft 13 is located at the center of the shell 11, the batching rake 12 is fixedly arranged on the circumference of the batching shaft 13, and the batching shaft 13 is driven to rotate by a motor, a feed pipe 17 is provided at the feed port 15, and the feed port 15 is opened on the upper part of the side wall of the shell 11, the shell 11 is cylindrical, and the bottom surface is a conical surface protruding downward, the discharge port 16 is opened at the center of the bottom surface of the shell 11, the discharge port 16 is connected to the discharge pipe 18, the overflow hole 14 is opened on the upper part of the side wall of the shell 11, and the overflow hole 14 is connected to the overflow pipe; the flotation device 2 is used to float the fine slag suspension concentrated by the solid-liquid mixing device 1; the flotation device 2 includes a flotation tank 21, a vent pipe 22, a tailings outlet 23, a flotation motor 24, a flotation rotor 25 and a scraper 26; the end of the discharge pipe 18 is located in the flotation tank 21, a discharge slot is provided on one side of the flotation tank 21, the flotation motor 24 is vertically fixed above the flotation tank 21 through a bracket, and the flotation rotor 25 is fixedly connected to the flotation motor On the output shaft of the flotation machine 24, the vent pipe 22 is passed through the outside of the flotation rotor 25, and the top is fixed on the bracket. An air intake pipe 221 connected to the air intake device is provided on the circumference of the vent pipe 22. The tailings outlet 23 is opened at the bottom of the flotation tank 21. The scraper 26 is arranged above the flotation tank 21 through the rotating shaft, and is used to scrape the foam layer on the surface of the flotation tank 21 from the discharge slot; the foam collecting device 3 is arranged behind the flotation device 2, and the foam collecting device 3 is used to receive the foam layer after flotation by the flotation device 2; the foam collecting device 3 is disc-shaped, and the bottom surface is a downwardly convex conical surface. The foam collecting device 3 is arranged below the discharge slot to receive the foam layer. A trumpet-shaped discharge port 31 is provided at the center of the bottom surface of the foam collecting device 3. The discharge port 31 A discharge pipe 32 is connected, and the foam collecting device 3 is connected to the screening device 4 through the discharge pipe 32; the screening device 4 is used to vibrate, screen and grade the foam layer collected by the foam collecting device 3; the screening device 4 includes a screening body 41, a screening inlet 42, a screen box cover 43, an observation port 44, a screen 45 and a receiving hopper 46; the screen box cover 43 is arranged above the screening body 41 to close the screening body 41, the screen 45 is inclined in the screening body 41, the screening inlet 42 and the observation port 44 are both arranged on the screen box cover 43, the screen box cover 43 is also inclined, and the screening inlet 42 is arranged at the highest point of the screen box cover 43, the receiving hopper 46 matches the screen 45, is inclined below the screen 45, and the discharge pipe 32 is connected to the screening inlet 42.

[0032] The fine slag suspension produced in the coal gasification process section is mixed and concentrated by setting a solid-liquid mixing device 1, and then floated by a flotation device 2 to obtain tailings and a foam layer, and then the foam layer is collected by a foam collecting device 3, and then the foam layer is sent to a screening device 4 for vibration screening to obtain a concentrate. Compared with the prior art in which the fine slag suspension is subjected to sedimentation, filtration and other steps to obtain solid waste coal gasification fine slag, which is generally treated by stacking and landfilling, different carbon-rich products are obtained after treatment by this device, and different carbon-rich products can be used for different purposes, thereby realizing the recovery of coal gasification fine slag. The fine slag suspension does not need to be settled and filtered before treatment, and the recovered products are more diverse and have wider uses. The fine slag suspension is added into the blending bin through the feed port 15, and the internal batching rake 12 drives the solid particles at the bottom to move under the rotation of the batching shaft 13 to prevent the solid particles from settling at the bottom. Under the action of gravity sedimentation and the batching rake 12, a flotation pulp with a suitable flotation solid-liquid ratio is obtained, and the flotation pulp is discharged from the discharge pipe 18 of the discharge port 16. The obtained water density is lower than that of the flotation pulp, and is discharged from the overflow pipe at the top of the blending bin. The water can also be used for coal gasification. The use of air washing in the process section is more conducive to material saving; by discharging the flotation pulp into the flotation tank 21 for flotation, the ash in the flotation pulp is generally hydrophilic, and the residual carbon is hydrophobic. The hydrophobic residual carbon gradually forms bubbles under the action of air and floats to the top to form a bubble layer, and the ash forms a pulp layer at the bottom. The pulp layer is discharged from the tailings outlet 23 at the bottom of the flotation tank 21. The discharged pulp layer is subjected to sedimentation and filtration to obtain tailings, thereby realizing the separation and recovery of residual carbon; the foam collecting device 3 is set to be a disc-shaped structure with a simple structure, and is arranged below the discharge slot to directly access the bubble layer, which is convenient to use; The foam layer is vibrated and screened by the screening body 41, and those that do not pass through the screen 45 are marked as primary concentrates, and those that pass through the screen 45 and fall into the receiving hopper 46 below are marked as secondary concentrates. The foam layer is further screened by the screening device 4, and the two can be used for different purposes. The primary concentrate has a large specific surface area, a developed microscopic pore size and a high carbon content, and can be used for the research of carbon materials, such as catalyst carriers, molecular sieves and adsorbents. Compared with the primary concentrate, the secondary concentrate has a smaller specific surface area and a lower carbon content, and can be returned to the furnace for combustion, thereby reducing coal consumption and improving the utilization rate and economic benefits of coal gasification fine slag.

[0033] A method for classifying coal gasification fine slag, using the above-mentioned device for classifying coal gasification fine slag, comprises the following steps:

[0034] S1. The fine slag suspension produced by the coal gasification process section is directly transported from the feed port 15 to the mixing bin, the motor of the solid-liquid mixing device 1 is turned on to make the mixing shaft 13 drive the mixing rake 12 to rotate, and the solid particles deposited on the bottom of the pool are pushed into the liquid to mix it into the flotation slurry. When the flotation slurry reaches 50kg / m 3The flotation pulp is discharged from the discharge port 16 after the solid-liquid ratio is 50kg / m 3 That is, one cubic meter of liquid contains 50 kg of solid;

[0035] S2. After the flotation device 2 receives the flotation pulp discharged from the discharge pipe 18, non-polar hydrocarbon oil is added into the flotation tank 21 as a flotation agent, and the amount is 10kg / t. When the flotation pulp reaches a certain height in the flotation tank 21, the flotation motor 24 and the air intake device are turned on. The speed of the flotation motor 24 is 1800rpm, and the air flow rate is 0.3m 3 / h, and at the same time, the motor driving the scraper 26 needs to be turned on, and the air intake device transports air to the flotation tank 21 through the air intake pipe 221 and the ventilation pipe 22. Under the action of air and flotation agent, the hydrophobic residual carbon forms bubbles and floats to the upper part of the flotation tank 21 to form a foam layer, and the ash-rich pulp layer is located at the lower part of the flotation tank 21. The pulp layer is discharged through the tailings outlet 23, and tailings are obtained after sedimentation and filtration. The foam layer is scraped into the foam collection device 3 by the scraper 26;

[0036] S3. After collecting a sufficient amount of foam layer, the foam collecting device 3 transports the foam layer to the screening body 41 through the screening inlet 42, turns on the motor of the screening body 41 for vibration screening, and the ore that passes through the screen 45 and falls into the receiving hopper 46 is the secondary concentrate, and the ore that does not pass through the screen 45 is the primary concentrate.

[0037] Through this method, the original fine slag suspension is directly subjected to solid-liquid blending, flotation and vibration screening treatment, which saves the pre-treatment steps compared to the existing method of first sedimentation, filtration and then treatment, and the mixed fine slag suspension is separated into tailings rich in inorganic ash, carbon-rich primary concentrate and secondary concentrate through the treatment of this method. Compared with the existing coal gasification fine slag treatment technology, the separation is more refined, and the tailings, primary concentrate and secondary concentrate can all be used for different purposes, thereby improving the recovery rate and economic benefits of coal gasification fine slag and realizing the quality classification of coal gasification fine slag.

[0038] It should be noted that the proportions in the drawings are not actual proportions.

Claims

1. A device for classifying coal gasification fine slag, characterized in that: include: A solid-liquid mixing device (1), wherein a feed port (15) and a discharge port (16) are provided on a shell (11), and the solid-liquid mixing device (1) is used to mix and concentrate the fine slag suspension produced in the coal gasification process section so as to achieve a solid-liquid ratio that meets flotation requirements; A flotation device (2) connected to the discharge port (16) of the solid-liquid mixing device (1), the flotation device (2) being used to float the fine slag suspension concentrated by the solid-liquid mixing device (1); A foam collecting device (3) is arranged behind the flotation device (2), and the foam collecting device (3) is used to receive the foam layer after flotation by the flotation device (2); A screening device (4) is connected to the discharge end of the foam collecting device (3), and the screening device (4) is used to screen and grade the foam layer collected by the foam collecting device (3).

2. The device for classifying coal gasification fine slag according to claim 1, characterized in that: The solid-liquid mixing device (1) comprises a hollow shell (11), a batching rake (12), a batching shaft (13) and an overflow hole (14); the space inside the shell (11) serves as a mixing chamber, the batching shaft (13) is vertically rotatably connected to the shell (11), and the batching shaft (13) is located at the center of the shell (11); the batching rake (12) is fixedly arranged on the circumference of the batching shaft (13), and the batching shaft (13) is driven by a motor. The housing (11) is designed to rotate dynamically, a feed pipe (17) is provided at the feed port (15), the feed port (15) is opened at the upper part of the side wall of the housing (11), the housing (11) is cylindrical, and the bottom surface is a conical surface protruding downward, the discharge port (16) is opened at the center of the bottom surface of the housing (11), the discharge port (16) is connected to the discharge pipe (18), the overflow hole (14) is opened at the upper part of the side wall of the housing (11), and the overflow hole (14) is connected to the overflow pipe.

3. The device for classifying coal gasification fine slag according to claim 2, characterized in that: The flotation device (2) comprises a flotation tank (21), a vent pipe (22), a tailings outlet (23), a flotation motor (24), a flotation rotor (25) and a scraper (26); the end of the discharge pipe (18) is located in the flotation tank (21), a discharge slot is provided on one side of the flotation tank (21), the flotation motor (24) is vertically fixed above the flotation tank (21) by a bracket, and the flotation rotor (25) is fixedly connected to the flotation motor The vent pipe (22) is arranged on the output shaft of the flotation rotor (24), the vent pipe (22) is passed through the outside of the flotation rotor (25), and the top is fixed on the bracket, an air intake pipe (221) connected to the air intake device is arranged on the circumference of the vent pipe (22), the tailings outlet (23) is opened at the bottom of the flotation tank (21), and the scraper (26) is arranged above the flotation tank (21) through a rotating shaft, and is used to scrape the foam layer on the surface of the flotation tank (21) out from the discharge slot.

4. The device for classifying coal gasification fine slag according to claim 3, characterized in that: The foam collecting device (3) is in the shape of a disk, and its bottom surface is a conical surface protruding downward. The foam collecting device (3) is arranged below the discharge slot to access the foam layer. A trumpet-shaped discharge port (31) is arranged at the center of the bottom surface of the foam collecting device (3). The discharge port (31) is connected to a discharge pipe (32). The foam collecting device (3) is connected to the screening device (4) via the discharge pipe (32).

5. The device for classifying coal gasification fine slag according to claim 4, characterized in that: The screening device (4) comprises a screening body (41), a screening inlet (42), a screen box cover (43), an observation port (44), a screen (45) and a receiving hopper (46); the screen box cover (43) is arranged above the screening body (41) to seal the screening body (41); the screen (45) is arranged obliquely in the screening body (41); the screening inlet (42) and the observation port (44) are both arranged on the screen box cover (43); the screen box cover (43) is also arranged obliquely, and the screening inlet (42) is arranged at the highest point of the screen box cover (43); the receiving hopper (46) matches the screen (45) and is arranged obliquely below the screen (45); and the discharge pipe (32) is connected to the screening inlet (42).

6. A method for classifying coal gasification fine slag, using the device for classifying coal gasification fine slag according to any one of claims 1 to 5, characterized in that: The steps include: S1. The fine slag suspension produced in the coal gasification process section is directly transported from the feed port (15) to the blending bin, the motor of the solid-liquid blending device (1) is turned on to rotate the batching shaft (13) to drive the batching rake (12), and the solid particles deposited on the bottom of the tank are pushed into the liquid to mix them into a flotation pulp. After the flotation pulp reaches a solid-liquid ratio that meets the flotation requirements, the flotation pulp is discharged from the discharge port (16); S2. After receiving the flotation pulp discharged from the discharge pipe (18), the flotation device (2) adds a flotation agent into the flotation tank (21). When the flotation pulp reaches a certain height in the flotation tank (21), the flotation motor (24) and the air intake device are turned on. At the same time, the motor driving the scraper (26) needs to be turned on. The air intake device transports air into the flotation tank (21) through the air intake pipe (221) and the ventilation pipe (22). Under the action of air and flotation agent, the hydrophobic residual carbon forms bubbles and floats to the upper part of the flotation tank (21) to form a foam layer. The ash-rich pulp layer is located at the lower part of the flotation tank (21) to form a pulp layer. The pulp layer is discharged through the tailings outlet (23). Tailings are obtained after sedimentation and filtration. The foam layer is scraped into the foam collection device (3) by the scraper (26); S3. After collecting a sufficient amount of foam layer, the foam collecting device (3) transports the foam layer to the screening body (41) through the screening inlet (42), turns on the motor of the screening body (41) for vibration screening, and the ore that passes through the screen (45) and falls into the receiving hopper (46) is the secondary concentrate, and the ore that does not pass through the screen (45) is the primary concentrate.

7. The method for classifying coal gasification fine slag according to claim 6, characterized in that: The solid-liquid ratio of the flotation slurry in step S1 is 50 kg / m 3 .

8. The method for classifying coal gasification fine slag according to claim 6, characterized in that: The flotation reagent in step S2 is non-polar hydrocarbon oil, and the dosage is 5-25 kg / t.

9. The method for classifying coal gasification fine slag according to claim 6, characterized in that: The speed of the flotation motor (24) in step S2 is 1500-2000 rpm, and the air flow rate is 0.2-5 m 3 / h.

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