A heavy media separation coal slime upgrading process

Abstract

This invention discloses a heavy media separation process for upgrading coal slime. Coal slime is pumped into a coal slime classifying hydrocyclone at a feed pressure of 110-150 kPa, resulting in underflow and overflow. The underflow, with a particle size of 0.15-1 mm, enters a coarse coal slime tank, where the coal slime concentration is adjusted to 30-33%. This 30-33% concentrated coal slime is then pumped into a spiral separator to obtain concentrate and tailings. The concentrate flows by gravity into a dewatering and deashing system, while the tailings are pumped into a separation and classification system. The overflow, the fine particle outlet of the dewatering and deashing system, and the fine particle outlet of the separation and classification system are all connected to a thickening system. This invention regulates the concentration of the underflow from the coal slime classifying hydrocyclone using a coarse coal slime tank, maintaining the coal slime concentration entering the spiral separator at 30-33%, thus improving the separation efficiency of the spiral separator and reducing the ash content of the concentrate and tailings, thereby improving the quality of the coal slime product.

Description

Technical Field

[0001] This invention relates to the field of coal slime separation technology, and in particular to a heavy media separation process for upgrading coal slime. Background Technology

[0002] Heavy media coal preparation is a physical coal preparation technology that uses a liquid with a density between that of clean coal and gangue as the separation medium. Its principle is based on buoyancy; clean coal, with a density lower than the medium, floats, while gangue or middlings, with a density higher than the medium, sink. These are then collected and classified into different products. In the preparation stage of heavy media coal preparation, to ensure the accuracy of heavy media separation, the raw coal is wet-screened before heavy media washing to remove fine particles. During wet screening, the fine particles mix with water to produce coal slurry and heavy media. The coal slime water generated during the dewatering and demediuming process of various selected products is usually classified by a hydrocyclone for thickening and classifying, and the coarse and fine coal slime is separated and recovered by a spiral separator. Then, it is dewatered by a linear high-frequency screen and a centrifuge to obtain the coarse and fine coal slime product. Due to the variation in the particle size composition of the raw coal, the underflow concentration of the hydrocyclone for thickening and classifying is high, and the separation accuracy of the spiral separator is reduced, resulting in back ash in the coarse and fine coal slime. The ash content of the coal slime product separated by heavy media is too high, and the product quality is unstable. Therefore, it is necessary to design a separation process to improve the separation accuracy of coal slime and reduce the ash content of the product. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a heavy medium separation coal slime upgrading process. By adjusting the concentration of the underflow of the coal slime classifier through the coarse coal slime bucket, the concentration of the coal slime entering the spiral separator is maintained at 30-33%, which improves the separation efficiency of the spiral separator and reduces the ash content of the spiral separator concentrate and tailings, thereby improving the quality of the coal slime product.

[0004] To achieve the above objectives, the technical solution adopted by this invention is: a heavy media separation coal slime upgrading process, comprising the following steps: Step S1: The heavy media separation coal slime is pumped into a coal slime classifying hydrocyclone for concentration and classification at a particle size of 0.15mm. The feed pressure of the coal slime classifying hydrocyclone is 110Kpa~150Kpa, resulting in underflow and overflow of the coal slime classifying hydrocyclone; Step S2: The coal slime particle size of the underflow of the coal slime classifying hydrocyclone is 0.15-1mm. The coal slime with a particle size of 0.15-1mm enters a coarse coal slime tank, where the coal slime concentration is adjusted to 30-33%; Step S3: S3: The 30-33% concentration coal slime from step S2 is pumped into a spiral separator for separation to obtain spiral separator concentrate and spiral separator tailings; Step S4: The spiral separator concentrate from step S3 flows by gravity into a dewatering and deashing system, and the coarse particle outlet of the dewatering and deashing system is connected to a clean coal bucket; Step S5: The spiral separator tailings from step S3 are pumped into a separation and grading system, and the coarse particle outlet of the separation and grading system is connected to a gangue bucket; Step S6: The overflow of the coal slime grading hydrocyclone from step S1, the fine particle outlet of the dewatering and deashing system from step S4, and the fine particle outlet of the separation and grading system from step S5 are all connected to a thickening system.

[0005] Preferably, the coarse coal slime bucket includes a bucket body, a concentration meter, a water supply valve, and a controller. The concentration meter is installed at 1 / 3 of the height of the bucket body from the ground. The water supply valve is installed on the top of the bucket body. The controller is installed on the outer wall of the bucket body. The controller is connected to the concentration meter and the water supply valve. The controller adjusts the opening degree of the water supply valve based on the coal slime concentration transmitted by the concentration meter.

[0006] Preferably, the coarse coal slime bucket further includes a motor and an agitator. The output shaft of the motor is connected to the agitator. The motor is installed on the top of the bucket body, and the agitator extends along the height direction of the bucket body to the bottom of the bucket body. The motor drives the agitator to stir the coal slime in the bucket body.

[0007] Preferably, two coarse coal slime buckets are connected in parallel.

[0008] Preferably, the dewatering and deashing system includes the following steps: Step S401: The concentrate from the spiral separator flows into the stacked screen by gravity to obtain the oversize material and the undersize coal slime; Step S402: The oversize material from the stacked screen in step S401 is sent to a coarse coal slime centrifuge for dewatering to obtain coarse and fine coal slime products, and the coarse and fine coal slime products are sent to a clean coal bin; Step S403: The undersize coal slime from the stacked screen in step S401 is sent to a thickening system through the fine particle outlet of the stacked screen for solid-liquid separation.

[0009] Preferably, the separation and grading system includes the following steps: Step S501: feeding the tailings of the spiral separator into a gangue hydrocyclone to obtain gangue hydrocyclone overflow and gangue hydrocyclone underflow; Step S502: feeding the gangue hydrocyclone underflow from step S501 into a high-frequency screen for screening to obtain high-frequency screen oversize and high-frequency screen undersize coal slime; Step S503: feeding the high-frequency screen oversize from step S502 into a gangue bucket; Step S504: feeding the gangue hydrocyclone overflow from step S501 and the high-frequency screen undersize coal slime from step S502 into a thickening system for solid-liquid separation.

[0010] Preferably, the concentration system includes the following steps: Step S601: feeding coal slime into a coal slime concentration tank for solid-liquid separation to obtain middlings; Step S602: feeding the middlings obtained in step S601 into an ultra-high pressure filter press for dewatering, and then feeding the middlings product into a middlings container.

[0011] Preferably, the sieve gap of the high-frequency sieve is 0.35 mm.

[0012] Preferably, the water supply valve is an electric water supply valve with an inner diameter of 150mm.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. This invention regulates the concentration of the underflow of the coal slime classifier by using a coarse coal slime bucket, so that the concentration of the coal slime entering the spiral separator is maintained at 30-33%, which improves the separation efficiency of the spiral separator, while reducing the ash content of the concentrate and tailings of the spiral separator, thus improving the quality of the coal slime product.

[0015] 2. The coarse coal slurry bucket of the present invention is equipped with a concentration meter on the side wall and a water supply valve on the top. The concentration meter continuously monitors the concentration of coal slurry in the coarse coal slurry bucket and sends the concentration data to the controller. The controller adjusts the opening of the water supply valve according to the received concentration data, thereby improving the stability of the coal slurry concentration in the coarse coal slurry bucket.

[0016] 3. The coarse coal slime bucket of the present invention is equipped with a stirrer. The stirrer is driven by a motor to rotate, which prevents the coal slime in the coarse coal slime bucket from settling and makes the coal slime in the coarse coal slime bucket evenly distributed, thereby improving the uniformity of the coal slime concentration in the coarse coal slime bucket.

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the present invention;

[0019] Figure 2 This is a schematic diagram of the structure of the coal slime bucket of the present invention.

[0020] Explanation of reference numerals in the attached figures:

[0021] 1—Barrel body; 2—Concentration meter; 3—Water supply valve;

[0022] 4—Controller; 5—Motor; 6—Agitator. Detailed Implementation

[0023] like Figure 1 As shown, this invention discloses a heavy media separation process for upgrading coal slime.

[0024] Example 1

[0025] The heavy media separation coal slime upgrading process includes the following steps:

[0026] Step S1: The heavy medium separation coal slime water pump is sent into the coal slime classifying hydrocyclone for concentration and classification according to the 0.15mm particle size. The feed pressure of the coal slime classifying hydrocyclone is 110Kpa~150Kpa, and the underflow and overflow of the coal slime classifying hydrocyclone are obtained.

[0027] The particle size of the overflow of the coal slime classifying hydrocyclone is less than 0.15 mm, the particle size of the underflow of the coal slime classifying hydrocyclone is 0.15-1 mm, the diameter of the coal slime classifying hydrocyclone is 350 mm, and the feed pump for pumping the heavy medium separation coal slime water is a variable frequency pump, which is convenient for adjusting the feed pressure of the coal slime classifying hydrocyclone.

[0028] Step S2: The coal slime particle size of the underflow of the coal slime classifier is 0.15-1mm. The coal slime with a particle size of 0.15-1mm enters the coarse coal slime bucket, and the coarse coal slime bucket adjusts the coal slime concentration in the bucket to 30-33%.

[0029] like Figure 2 As shown, the coarse coal slime bucket includes a bucket body 1, a concentration meter 2, a water supply valve 3, and a controller 4. The concentration meter 2 is installed at 1 / 3 of the height of the bucket body 1 from the ground. The water supply valve 3 is installed on the top of the bucket body 1. The controller 4 is installed on the outer wall of the bucket body 1. The controller 4 is connected to the concentration meter 2 and the water supply valve 3. The controller 4 adjusts the opening of the water supply valve 3 based on the coal slime concentration transmitted by the concentration meter 2.

[0030] The underflow of the coal slime classifier is fed into the barrel 1 through a pipe. The concentration meter 2 on the side wall of the barrel 1 continuously detects the concentration of coal slime in the barrel 1 and transmits the concentration value to the controller 4. If the concentration meter 2 detects that the concentration of coal slime in the barrel 1 is greater than 33%, the controller 4 receives the concentration data and controls the opening of the water supply valve 3. The water supply valve 3 supplies water to the barrel 1. The concentration meter 2 continuously detects the concentration of coal slime in the barrel 1. When the concentration meter 2 detects that the concentration of coal slime in the barrel 1 is lower than 33%, the controller 4 controls the water supply valve 3 to close, and the water supply valve 3 stops supplying water to the barrel 1. The concentration meter 2 keeps the concentration of coal slime in the barrel 1 at 30%-33%, which avoids the pipeline blockage caused by excessive underflow concentration of the coal slime classifier. At the same time, keeping the coal slime at a concentration of 30%-33% can improve the separation efficiency of the spiral separator and reduce the amount of back ash in the concentrate and tailings separated by the spiral separator.

[0031] like Figure 2 As shown, the coarse coal slime bucket also includes a motor 5 and a stirrer 6. The output shaft of the motor 5 is connected to the stirrer 6. The motor 5 is installed on the top of the bucket body 1, and the stirrer 6 extends along the height direction of the bucket body 1 to the bottom of the bucket body 1. The motor 5 drives the stirrer 6 to stir the coal slime in the bucket body 1.

[0032] After the underflow of the coal slime classifier enters the barrel 1, the coal slime is unevenly distributed. The agitator 6 continuously stirs the coal slime in the barrel 1 to keep the coal slime concentration in the barrel 1 uniform and improve the separation efficiency of the spiral separator.

[0033] Step S3: Pump the 30-33% concentration coal slime from step S2 into a spiral separator for separation to obtain spiral separator concentrate and spiral separator tailings;

[0034] Coal slime with a concentration of 30-33% in the coarse coal slime bucket is pumped into the spiral separator by a variable frequency pump. It rotates along the spiral groove. During the movement, light and heavy particles are subjected to gravity, centrifugal force, friction, and water flow pressure in the spiral groove. Materials with different particle sizes and densities have different movement trajectories in the spiral groove, and high-density coal slime and low-density coal slime are separated. At the bottom of the spiral separator, high-density coal slime and low-density coal slime are collected by different chutes, which yields the tailings and concentrate of the spiral separator. The coal slime concentration is controlled at 30-33% to avoid excessive coal slime concentration, which may cause material accumulation in the feed distribution box of the spiral separator, blockage of the feed pipe, or uneven feeding of the spiral separator, thus affecting the coal slime separation effect.

[0035] Step S4: The concentrate from the spiral separator in step S3 flows into the dewatering and deashing system by gravity, and the coarse particle outlet of the dewatering and deashing system is connected to the clean coal bucket.

[0036] The dewatering and deashing system includes the following steps:

[0037] Step S401: The concentrate from the spiral separator flows into the stacked screen by gravity to obtain the oversize material and the undersize coal slime of the stacked screen.

[0038] The coal slime particles on the stacked screen have a diameter greater than 0.074 mm, while the coal slime particles under the stacked screen have a diameter less than 0.074 mm.

[0039] Step S402: The material overlaid on the stacked screen in step S401 is sent to a coarse coal slime centrifuge for dewatering to obtain coarse and fine coal slime products. The coarse and fine coal slime products are then sent to a clean coal bin.

[0040] After the coarse coal slime centrifuge dewaters the material on the stacked screen, the material is sent to the clean coal bin.

[0041] Step S403: The coal slime undersized from the stacked screen in step S401 is sent to the thickening system through the fine particle outlet of the stacked screen for solid-liquid separation.

[0042] The coal slurry under the screen of the stacked screen is sent to the coal slurry thickening tank through the pipeline for solid-liquid separation. The coal slurry thickening tank then sends the dewatered coal slurry under the screen of the stacked screen to an ultra-high pressure filter press for dewatering and filtration to obtain the middlings product, which is then sent to the middlings bin.

[0043] Step S5: The tailings from the spiral separator in step S3 are pumped into the separation and grading system, and the coarse particle outlet of the separation and grading system is connected to the gangue bucket.

[0044] The separation and grading system includes the following steps:

[0045] Step S501: Feed the tailings from the spiral separator into the gangue hydrocyclone to obtain the gangue hydrocyclone overflow and gangue hydrocyclone underflow;

[0046] Step S502: The underflow of gangue from the hydrocyclone in step S501 is fed into a high-frequency screen for screening to obtain the oversize material and the undersize coal slime.

[0047] The screen opening of the high-frequency screen is 0.35mm. The particle size of the coal slime on the high-frequency screen is 0.35-1mm, and the particle size of the coal slime under the high-frequency screen is less than 0.35mm.

[0048] Step S503: Send the material overlaid from the high-frequency screen in step S502 into the gangue bucket;

[0049] Step S504: The overflow from the gangue hydrocyclone in step S501 and the coal slime under the high-frequency screen in step S502 are sent to the thickening system for solid-liquid separation.

[0050] The coal slime and gangue overflowing from the high-frequency screen into the coal slime thickening tank are separated into solid and liquid. The separated coal slime is sent to the ultra-high pressure filter press for dewatering and the resulting middlings product is sent to the middlings container.

[0051] Step S6: The overflow of the coal slime cyclone separator in step S1, the fine particle outlet of the dewatering and deashing system in step S4, and the fine particle outlet of the separation and grading system in step S5 are all connected to the thickening system.

[0052] Step S601: The feed coal slime is sent into the coal slime thickening tank for solid-liquid separation to obtain medium coal slime;

[0053] The feed coal slime includes the overflow of the coal slime grading hydrocyclone, the coal slime under the screen of the stacked screen, the overflow of the gangue hydrocyclone, and the coal slime under the screen of the high-frequency screen.

[0054] Step S602: After the medium coal slime from step S601 is fed into an ultra-high pressure filter press for dewatering, the medium coal slime product is fed into a medium coal hopper.

[0055] There are two coarse coal slime buckets connected in parallel.

[0056] One coal slurry bucket serves as an emergency backup bucket.

[0057] Water supply valve 3 is an electric water supply valve with an inner diameter of 150mm.

[0058] Example 1 was used to process batches 1-10 of raw coal. The raw coal was numbered 1-10 according to its batch number. The feed concentration of the spiral separator, the ash content of the spiral separator concentrate and tailings, and the ash content of the clean coal slime product after centrifuge dewatering were tested and recorded. The test results are shown in Table 1.

[0059] Comparative Example 1

[0060] The difference between Comparative Example 1 and Example 1 is that the underflow of the coal slime grading hydrocyclone flows into the spiral separator by gravity, and the concentration of the coal slime entering the spiral separator is not adjusted.

[0061] Comparative Example 1 was used to process batches 1-10 of raw coal from the mine. The raw coal was numbered sequentially from 1 to 10 according to its batch number. The feed concentration of the spiral separator, the ash content of the spiral separator concentrate and tailings, and the ash content of the clean coal slime product after centrifuge dewatering were tested and recorded. The test results are shown in Table 1.

[0062] Table 1 shows the test results of the first to ten batches of raw coal treated with Example 1 and Comparative Example 1, respectively.

[0063] Table 1

[0064]

[0065] As shown in Table 1, the ash content of the spiral separator concentrate treated using Example 1 is lower than that of the same batch of spiral separator concentrate obtained in Comparative Example 1. This indicates that the technical solution provided in this application can reduce the ash content of the spiral separator concentrate by adjusting the feed concentration of the spiral separator. Furthermore, the ash content of the coarse coal slime product obtained using Example 1 is lower than that of the same batch of coarse coal slime product obtained in Comparative Example 1, indicating that the technical solution provided in this application can reduce the ash content of the clean coal slime product. Calculations from the data in Table 1 show that the ash content of the first-to-last batch of concentrate treated using Example 1... For batch 0 of raw coal, the average feed concentration of the spiral separator was 31%, the average ash content of the spiral separator concentrate was 13.32%, and the average ash content of the coarse and fine coal slime product was 11.39%. For batches 1-10 of raw coal treated with Comparative Example 1, the average feed concentration of the spiral separator was 39%, the average ash content of the spiral separator concentrate was 16.39%, and the average ash content of the coarse and fine coal slime product was 16.07%. This indicates that the technical solution provided in this application can improve the separation effect of the spiral separator and ensure accurate separation of coarse and fine coal slime from high-ash coal slime.

[0066] As shown in Table 1, the ash content deviation between the concentrate and coarse coal slime product treated with Example 1 is greater than that in Comparative Example 1. This indicates that the technical solution provided in this application can improve the ash removal effect of the spiral separator by adjusting the feed concentration. Calculations from the data in Table 1 show that for the first 10 batches of raw coal treated with Example 1, the average ash content deviation between the concentrate and coarse coal slime product was 1.93%, while for the first 10 batches of raw coal treated with Comparative Example 1, the average ash content deviation was 0.32%. This indicates that the technical solution provided in this application can increase the ash removal rate of the spiral separator and improve the quality of the coarse coal slime product.

[0067] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural transformations made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A dense medium separation coal slime upgrading process, characterised in that, Includes the following steps: Step S1: The heavy medium separation coal slime water pump is sent into the coal slime classifying hydrocyclone for concentration and classification according to the 0.15mm particle size. The feed pressure of the coal slime classifying hydrocyclone is 110Kpa~150Kpa, and the underflow and overflow of the coal slime classifying hydrocyclone are obtained. Step S2: The coal slime particle size of the underflow of the coal slime classifier is 0.15-1mm. The coal slime with a particle size of 0.15-1mm enters the coarse coal slime bucket, and the coarse coal slime bucket adjusts the coal slime concentration in the bucket to 30-33%. Step S3: Pump the 30-33% concentration coal slime mentioned in step S2 into a spiral separator for separation to obtain spiral separator concentrate and spiral separator tailings; Step S4: The concentrate from the spiral separator mentioned in step S3 flows into the dewatering and deashing system by gravity, and the coarse particle outlet of the dewatering and deashing system is connected to the clean coal bucket. Step S5: The tailings from the spiral separator mentioned in step S3 are pumped into the separation and grading system, and the coarse particle outlet of the separation and grading system is connected to the gangue bucket. Step S6: The overflow of the coal slime cyclone separator mentioned in step S1, the fine particle outlet of the dewatering and deashing system in step S4, and the fine particle outlet of the separation and grading system in step S5 are all connected to the thickening system. The separation and grading system includes the following steps: Step S501: The tailings of the spiral separator are fed into the gangue hydrocyclone to obtain gangue hydrocyclone overflow and gangue hydrocyclone underflow; Step S502: The underflow of the gangue hydrocyclone described in step S501 is fed into a high-frequency screen for screening to obtain the oversize material and the undersize coal slime. Step S503: Feed the material overlaid from the high-frequency screen described in step S502 into the gangue bucket; Step S504: The overflow from the gangue hydrocyclone described in step S501 and the coal slime under the high-frequency screen described in step S502 are sent to the thickening system for solid-liquid separation. The dewatering and deashing system includes the following steps: Step S401: The concentrate from the spiral separator flows into the stacked screen by gravity to obtain the oversize material and the undersize coal slime. Step S402: The material overlaid on the stacked screen described in step S401 is fed into a coarse coal slime centrifuge for dewatering to obtain coarse and fine coal slime products, and the coarse and fine coal slime products are fed into a clean coal bin. Step S403: The coal slime under the screen of the stacked screen described in step S401 is sent to the thickening system through the fine particle outlet of the stacked screen for solid-liquid separation. The concentration system includes the following steps: Step S601: The feed coal slime is sent into the coal slime thickening tank for solid-liquid separation to obtain medium coal slime; Step S602: After the medium coal slime described in step S601 is fed into an ultra-high pressure filter press for dewatering, the medium coal slime product is fed into a medium coal hopper.

2. A dense medium coal slime upgrading process according to claim 1, characterised in that, The coarse coal slime bucket includes a bucket body (1), a concentration meter (2), a water supply valve (3), and a controller (4). The concentration meter (2) is installed on the bucket body (1) at a height of 1 / 3 above the ground. The water supply valve (3) is installed on the top of the bucket body (1). The controller (4) is installed on the outer wall of the bucket body (1). The controller (4) is connected to the concentration meter (2) and the water supply valve (3). The controller (4) adjusts the opening of the water supply valve (3) based on the coal slime concentration transmitted by the concentration meter (2).

3. A dense medium separation coal slime upgrading process as claimed in claim 2, characterised in that, The coarse coal slurry bucket also includes a motor (5) and a stirrer (6). The output shaft of the motor (5) is connected to the stirrer (6). The motor (5) is installed on the top of the bucket body (1). The stirrer (6) extends along the height direction of the bucket body (1) to the bottom of the bucket body (1). The motor (5) drives the stirrer (6) to stir the coal slurry in the bucket body (1).

4. A dense medium coal slime upgrading process according to claim 1 characterised in that, Two coarse coal slime buckets are connected in parallel.

5. A dense medium coal slime upgrading process according to claim 1 characterised in that, The sieve gap of the high-frequency screen is 0.35mm.

6. A dense medium coal slime upgrading process according to claim 2 characterised in that, The water supply valve (3) is an electric water supply valve with an inner diameter of 150mm.

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