A method and system for dewatering clean coal from a dense medium cyclone

Abstract

The present application provides a heavy medium cyclone clean coal dewatering method and system, which belongs to the technical field of coal washing. In the existing dewatering process of the vibration screen and the horizontal vibration discharge centrifuge, a double air source composite dry separation machine is added between the vibration screen and the horizontal vibration discharge centrifuge. The double air source composite dry separation machine separates the material on the screen of the vibration screen into fine particle product and coarse and heavy particle product. The horizontal vibration discharge centrifuge is used for dewatering the fine particle product, and hot air is used for directly drying the coarse and heavy particle product. The dried coarse and heavy particle product and the dewatered fine particle product are the final dewatered products. Only the fine particle product is selected for centrifugal separation, which can effectively improve the dewatering efficiency and prolong the service life of the horizontal vibration discharge centrifuge.

Description

Technical Field

[0001] This invention belongs to the field of coal washing and beneficiation technology, specifically relating to a method and system for dewatering clean coal using a heavy medium cyclone separator. Background Technology

[0002] Thermal coal is generally composed of low-rank coal with high water-holding capacity, making improving dewatering efficiency a crucial task for coal preparation plants. Currently, the basic process for removing moisture from thermal coal fines is a combination of a fixed screen, a vibrating screen, and a horizontal vibrating discharge centrifuge. The process involves feeding the fine coal slurry into a fixed screen, then feeding the material over the screen into a linear vibrating screen with 1-3mm apertures. All material over the linear vibrating screen is then fed into the horizontal vibrating discharge centrifuge to become the final product. In practical thermal coal production, observations of the vertical distribution of moisture content along the material layer revealed that the moisture content in the upper layer of the oversize material and the high-density portion of the clean coal already meets product requirements. However, due to the high water-holding capacity of thermal coal, the humidity inside the centrifuge casing is high during the removal of fine coal fines, reaching over 80% in field tests. This leads to reabsorption after dewatering, resulting in increased product moisture content.

[0003] Existing methods for dewatering power coal powder mainly using vibrating screens and centrifuges have drawbacks. In the vibrating screen dewatering stage, the upper layer of moisture and the high-density portion of the material on the screen have acceptable moisture levels, but these materials are all sent to the centrifuge for further dewatering. This wastes the centrifuge's processing capacity and increases the humidity within the centrifuge, worsening the dewatering effect. This invention proposes a dual-air-source composite dry separation method to extract the acceptable moisture content material and a centrifuge dehumidification system. This allows for timely and dynamic separation of the acceptable material from the vibrating screen and improves the centrifuge dewatering environment, thereby increasing the dewatering efficiency of power coal powder. Summary of the Invention

[0004] To address the shortcomings of existing technologies, a method and system for dewatering clean coal using a heavy medium cyclone separator is provided. The process is simple, using a dual-air-source composite dry separator to pre-separate coarse and heavy granular coal that does not require centrifugal dewatering. Hot air can then be used for air drying. The separated fine particles are then centrifuged for dewatering, effectively improving the efficiency of centrifugal dewatering and extending the service life of the horizontal vibrating discharge centrifuge.

[0005] To achieve the above-mentioned technical objectives, this invention discloses a method for dewatering clean coal using a heavy medium cyclone separator. In the existing dewatering process using a vibrating screen and a horizontal vibrating discharge centrifuge, a dual-air-source composite dry separator is added between the vibrating screen and the horizontal vibrating discharge centrifuge. The vibrating screen feeds the material onto the screen into the dual-air-source composite dry separator, which separates the material through vibration in a humid air environment, forming fine particle belts and coarse and heavy particle belts. The horizontal vibrating discharge centrifuge dewaters the fine particle belt product, and hot air directly dries the coarse and heavy particle belt products in the dual-air-source composite dry separator. The dried coarse and heavy particle belt products, along with the dewatered fine particle belt product, constitute the final dewatered product. This method selects only the fine particle belt product for centrifugal separation, effectively extending the lifespan of the horizontal vibrating discharge centrifuge and improving the dewatering efficiency.

[0006] The specific steps are as follows:

[0007] First, the heavy medium cyclone fine coal slurry is screened using a vibrating screen, and then all the material on the vibrating screen is fed into a dual-air source compound dry separator.

[0008] In a dual-air-source composite dry separator, the material is divided into two parts—a fine particle belt and a coarse / heavy particle belt—by vibration in a humid air environment. During the separation process, since larger particles vibrate more at the same vibration frequency, the particle size range of the fine particle belt and the coarse / heavy particle belt can be adjusted by adjusting the vibration frequency or the height of the separation baffle between the fine particle belt and the coarse / heavy particle belt.

[0009] Only fine particles are fed into a horizontal vibrating discharge centrifuge for centrifugal dehydration. During the dehydration process, a vacuum pump is used to extract humid air from the horizontal vibrating discharge centrifuge as the humid air source for the dual-source composite dry separator. Then, a second air compressor is used to pressurize the humid air in the humid air source and blow it into the composite dry separator. This not only removes dust but also increases the air density in the dual-source composite dry separator, which helps to better separate fine particles from coarse particles.

[0010] High-speed hot airflow is used as the dry air source to directly dry the coarse and heavy particles in the belt that are still vibrating inside the dual-air source composite dry separator.

[0011] The fine particle belt product after centrifugal dewatering and the coarse and heavy particle belt products after high-speed hot air flow drying are output to form the final dewatered clean coal product.

[0012] Furthermore, the high-speed hot airflow is generated by a compressor and a hot air blower. The compressor collects preheating from the surrounding equipment and further pressurizes it. The hot air blower then heats and dries the coarse and heavy particle belt products.

[0013] Furthermore, the temperature of the dry air source is between 80℃ and 120℃.

[0014] Furthermore, the horizontal vibrating discharge centrifuge is a suction-type horizontal vibrating discharge centrifuge. The air intake of the suction-type horizontal vibrating discharge centrifuge is located in the area tangentially downward in the direction of the screen basket's movement, which facilitates the recovery of humid air.

[0015] Furthermore, the centrifugal liquid separated by the horizontal vibrating unloading centrifuge is recycled after coal slurry water treatment.

[0016] A heavy medium cyclone coal dewatering system includes a dual-source composite dry separator. The inlet of the dual-source composite dry separator is connected to a vibrating screen. The dual-source composite dry separator is based on a composite dry separator with the addition of a wet air source and a dry air source. The wet air source introduces humid air into the separation areas of the fine particle belt and the coarse and heavy particle belts, effectively reducing dust and improving the separation effect. The coarse and heavy particle belts on the composite dry separator are dewatered using the dry air flow provided by the dry air source. The fine particle belt is connected to a horizontal vibrating discharge centrifuge. The horizontal vibrating discharge centrifuge is equipped with a vacuum pump that can draw in the internal humid air. The vacuum pump is connected to a second air compressor that uses the humid air drawn in by the vacuum pump as the wet air source. The dry air source is dry air heated and pressurized by the first air compressor and a hot air blower.

[0017] Furthermore, high-speed hot air flow is used to heat and dry coarse and heavy particle belt products by utilizing fluidized beds, mixing equipment, or free-fall conveying devices.

[0018] Beneficial effects: This method uses a dual-air-source composite dry separator to pre-separate coarse and heavy granular coal that does not require centrifugal dewatering. Hot air can be used to achieve air drying, while the separated fine particles are centrifuged for dewatering. This effectively improves the efficiency of centrifugal dewatering, effectively reduces the feed amount of the horizontal vibrating discharge centrifuge, improves the centrifuge dewatering environment, enhances the dewatering effect, and extends the service life of the horizontal vibrating discharge centrifuge.

[0019] This device promptly grades and separates high-density materials after the dewatering screen of the fine coal powder, and creates a dry air environment in the centrifuge stage. On the one hand, it significantly reduces the amount of material entering the subsequent centrifuge and improves the centrifuge processing effect; on the other hand, it provides a suitable working environment for the centrifuge and improves the dewatering efficiency of the fine coal powder. Attached Figure Description

[0020] Figure 1 This is a flowchart of the method for dewatering clean coal using a heavy medium cyclone in an embodiment of the present invention;

[0021] Figure 2 This is a schematic diagram of a dual-air-source composite dry sorting machine in an embodiment of the present invention.

[0022] In the diagram: A - Vibrating screen, B - Dual-source composite dry separator, C - Hot air blower, D - Air compressor one, E - Horizontal vibrating discharge centrifuge, F - Vacuum pump, G - Air compressor two Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings:

[0024] like Figure 1 As shown, this invention discloses a method for dewatering clean coal using a heavy medium cyclone separator. The clean coal slurry from the heavy medium cyclone separator is fed into a vibrating screen A; the material on the screen is fed into a dual-air-source composite dry separator B, which separates it into a fine particle belt and a coarse particle belt; the fine particle belt material is fed into a horizontal vibrating centrifuge E; a vacuum pump F extracts the humid air from the centrifuge E; the humid air is blown into the fine particle belt by a second air compressor G, and the air is fed into the coarse particle belt after passing through a first air compressor D and a hot air blower C; the coarse particle belt material is mixed with the centrifuge product to become the final product.

[0025] A heavy medium cyclone dewatering system for clean coal includes a dual-source composite dry separator B, the inlet of which is connected to a vibrating screen A. Figure 2 As shown, the dual-source composite dry separator B is based on the composite dry separator with the addition of a wet air source and a dry air source. The wet air source introduces humid air into the separation areas of the fine particle belt and the coarse and heavy particle belts, effectively reducing dust and improving the separation effect. The coarse and heavy particle belts on the composite dry separator are dehydrated using the dry air flow provided by the dry air source. The fine particle belt is connected to a horizontal vibrating discharge centrifuge E, which is equipped with a vacuum pump F that can draw in the internal humid air. The vacuum pump F is connected to a compressor G that uses the humid air drawn in by the vacuum pump F as the wet air source. The dry air source is dry air heated and pressurized by a compressor D and a hot air blower C.

[0026] like Figure 1 As shown, a method for dewatering clean coal using a heavy medium cyclone separator includes the following steps:

[0027] First, vibrating screen A is used to screen the heavy medium cyclone slurry of long-flame coal. Then, all the material on the screen of vibrating screen A is fed into dual-air source compound dry separator B. At this time, the moisture content in the clean coal is within 20%.

[0028] The dual-air-source composite dry separator B uses a vibrator to separate the fed material into two parts: fine particle belt products and coarse and heavy particle belt products through physical vibration.

[0029] Only fine particle belt products are fed into a horizontal vibrating discharge centrifuge for centrifugal dehydration. During the dehydration process, a vacuum pump F is used to extract humid air from the horizontal vibrating discharge centrifuge E as the humid air source for the dual-air source composite dry separator B. Then, the humid air is pressurized by a blower G and blown into the sorting area of ​​the composite dry separator B to help reduce dust and improve the sorting effect of fine particle belts.

[0030] Hot air from a dry air source is used to heat and dry the coarse and heavy particle belt products that are still vibrating on the dual-air-source composite dry separator B.

[0031] The fine particle belt product after centrifugal dewatering and the coarse and heavy particle belt products after high-speed hot air flow drying are output to form the final dewatered clean coal product.

[0032] Example: A coal preparation plant uses long-flame coal as its raw material. A combination of a vibrating screen and a horizontal vibrating discharge centrifuge is used to remove moisture from the fine coal. All material overboard from vibrating screen A is fed into the horizontal vibrating discharge centrifuge B to become the final product, with a moisture content of approximately 17%. To improve dewatering efficiency, the plant feeds the fine coal slurry into vibrating screen A, then into a dual-air-source composite dry separator B, separating it into a fine particle belt and coarse / heavy particle sections. The fine particle section is fed through a chute into the existing horizontal vibrating discharge centrifuge E. Moist air inside the centrifuge E is drawn in by vacuum pump F, then pressurized by blower G, and blown into the fine particle belt of the composite dry separator B. The air is then heated by blower D and hot air fan C and fed into the coarse / heavy particle belt of the centrifuge B. The coarse / heavy particle belt product is mixed with the product from the centrifuge E to become the final product. The product moisture content is reduced by 2 percentage points compared to the previous process, and the lifespan of the screen basket in the centrifuge E is extended by more than 30%.

Claims

1. A method for dewatering clean coal using a heavy medium cyclone separator, characterized in that: The heavy medium cyclone clean coal dewatering system uses a dual-source composite dry separator (B) added between the vibrating screen (A) and the horizontal vibrating discharge centrifuge (E). The inlet of the dual-source composite dry separator (B) is connected to the vibrating screen (A). The dual-source composite dry separator (B) is based on the composite dry separator with the addition of a wet air source and a dry air source. The wet air source is the humid air introduced into the separation area of ​​fine particles and coarse and heavy particles. The coarse and heavy particles on the composite dry separator are dewatered using the dry air flow provided by the dry air source. The fine particles enter the horizontal vibrating discharge centrifuge (E). The horizontal vibrating discharge centrifuge (E) is equipped with a vacuum pump (F) that can draw in the internal humid air. The vacuum pump (F) is connected to a second air compressor (G) that uses the humid air drawn in by the vacuum pump (F) as the wet air source. The dry air source is dry air heated and pressurized by a first air compressor (D) and a hot air blower (C). The specific steps are as follows: First, the heavy medium cyclone fine coal slurry is screened using a vibrating screen (A), and then all the material on the vibrating screen (A) is fed into a dual-air source compound dry separator (B). The dual-source composite dry separator (B) separates the fed material into two parts, a fine particle belt and a coarse and heavy particle belt, by vibration in a humid air environment. During the separation process, at the same vibration frequency, the larger the mass of the particles, the greater the vibration amplitude. By adjusting the vibration frequency or the height of the separation baffle between the fine particle belt and the coarse and heavy particle belt, the particle size range of the fine particle belt and the coarse and heavy particle belt can be adjusted. Only fine particles are fed into a horizontal vibrating discharge centrifuge for centrifugal dehydration. During the dehydration process, a vacuum pump (F) is used to extract humid air from the horizontal vibrating discharge centrifuge (E) as the humid air source for the dual-source composite dry separator (B). Then, a second air compressor (G) is used to pressurize the humid air in the humid air source and blow it into the composite dry separator (B). This not only removes dust but also increases the air density in the dual-source composite dry separator (B) to assist in the separation of fine particles from coarse particles. High-speed hot airflow is used as the dry air source to directly dry the product in the coarse and heavy particle belt that is still vibrating in the dual-air source composite dry separator (B); The fine particle belt product after centrifugal dewatering and the coarse and heavy particle belt products after high-speed hot air flow drying are output to form the final dewatered clean coal product.

2. The method for dewatering clean coal using a heavy medium cyclone according to claim 1, characterized in that, The high-speed hot airflow is generated by a compressor (D) and a hot air blower (C). The compressor (D) collects waste heat from the surrounding equipment to further pressurize the airflow, and the hot air blower (C) heats and dries the coarse and heavy particle belt products.

3. The method for dewatering clean coal using a heavy medium cyclone according to claim 2, characterized in that, The temperature of the dry air source is between 80℃ and 120℃.

4. The method for dewatering clean coal using a heavy medium cyclone according to claim 1, characterized in that, The horizontal vibrating discharge centrifuge (E) is a suction horizontal vibrating discharge centrifuge. The suction port of the suction horizontal vibrating discharge centrifuge is located in the area tangentially downward in the direction of screen basket movement, which facilitates the recovery of humid air.

5. The method for dewatering clean coal using a heavy medium cyclone according to claim 1, characterized in that, The centrifugal liquid separated by the horizontal vibrating discharge centrifuge (E) is recycled after coal slurry water treatment.

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