Clean coal dehydration method and system of dense medium cyclone

Abstract

The invention provides a dense medium cyclone clean coal dehydration method and system, and belongs to the technical field of coal washing. In the dewatering process of an existing vibrating screen and a horizontal vibrating discharging centrifugal machine, a double-air-source combined type dry sorting machine is additionally arranged between the vibrating screen and the horizontal vibrating discharging centrifugal machine, and materials on the vibrating screen are sorted through the double-air-source combined type dry sorting machine to form fine particle belt products, coarse particle belt products and heavy particle belt products. A horizontal vibration discharging centrifugal machine is used for dewatering fine particle belt products, hot air is used for directly drying coarse particle belt products and heavy particle belt products, the dried coarse particle belt products, the dried heavy particle belt products and the dewatered fine particle belt products are final dewatered products, only the fine particle belt products are selected for centrifugal separation, the dewatering efficiency can be effectively improved, and the production cost is reduced. And the service life of the horizontal vibration discharging centrifugal machine is prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of coal washing, and in particular relates to a method and system for dehydrating clean coal in a heavy medium cyclone. Background Art

[0002] Thermal coal is generally low-rank coal with strong water holding capacity. Improving the dehydration efficiency of thermal coal has always been an important task of coal preparation plants. At present, thermal coal basically adopts the mode of fixed screen + vibrating screen + horizontal vibrating unloading centrifuge to remove moisture from fine clean coal. The process is that the fine clean coal slurry is fed into the fixed screen, and the material on the screen is fed into the linear vibrating screen with a screen hole of 1-3mm. All the materials on the linear vibrating screen are fed into the horizontal vibrating unloading centrifuge to become the final product. In the practice of thermal coal production, by examining the vertical distribution of moisture content of the product on the screen along the material layer, it is found that the moisture content of the upper part of the material on the screen and the high-density part of the clean coal has reached the product requirements. At the same time, thermal coal has a strong water holding capacity. When using a centrifuge to remove the fine clean coal of thermal coal, the humidity in the casing is relatively high. The on-site test basically reaches more than 80%, which leads to reabsorption of the dehydrated product and an increase in the moisture content of the product.

[0003] The existing dehydration method of thermal coal fines mainly based on vibrating screens and centrifuges has the problem that the moisture content of the upper layer of the screened material and the moisture content of the high-density part in the vibrating screen dehydration link are qualified, and all these materials enter the centrifuge for dehydration, which wastes the processing capacity of the centrifuge and increases the humidity in the centrifuge body, deteriorating the dehydration effect of the centrifuge. The present invention intends to use a dual-wind source composite dry separation method to extract the material with qualified moisture content and a centrifuge dehumidification method to timely and dynamically separate the qualified material on the vibrating screen, improve the dehydration environment of the centrifuge, and improve the dehydration efficiency of the thermal coal fines. Summary of the invention

[0004] In view of the shortcomings of the prior art, a method and system for dehydrating clean coal using a heavy medium cyclone is provided. The method and system have simple steps. A dual-air source composite dry separator is used to separate the coarse and heavy coal particles that do not need to be centrifugally dehydrated in advance. Hot air can be used for air drying, and the separated fine particles are centrifugally dehydrated, which effectively improves the efficiency of centrifugal dehydration and extends the service life of the horizontal vibrating unloading centrifuge.

[0005] To achieve the above technical objectives, the present invention discloses a method for dehydrating clean coal in a heavy medium cyclone. In the dehydration process of an existing vibrating screen and a horizontal vibrating unloading centrifuge, a dual-air source composite dry separator is added between the vibrating screen and the horizontal vibrating unloading centrifuge. The vibrating screen sends the material on the screen into the dual-air source composite dry separator. The dual-air source composite dry separator separates the material by vibration in a humid air environment to form a fine particle band and a coarse and heavy particle band. The horizontal vibrating unloading centrifuge is used to dehydrate the product of the fine particle band. Hot air is used to directly dry the coarse and heavy particle band products in the dual-air source composite dry separator. The dried coarse and heavy particle band products and the dehydrated fine particle band products are the final dehydrated products. The method only selects the fine particle band product for centrifugal separation, effectively prolongs the life of the horizontal vibrating unloading centrifuge and improves the dehydration efficiency.

[0006] The specific steps are as follows: Firstly, the heavy medium cyclone clean coal slurry is screened by a vibrating screen, and then all the materials on the vibrating screen are fed into a dual-air source composite dry separator; In the dual-air source composite dry separator, the material fed is divided into two parts, a fine particle belt and a coarse and heavy particle belt, by means of vibration in a humid air environment. During the sorting process, since the larger the mass of the particle is, the greater the vibration amplitude is at the same vibration frequency, the particle size range of the fine particle belt and the coarse and heavy particle belt can be adjusted by adjusting the vibration frequency or the height of the separation partition separating the fine particle belt and the coarse and heavy particle belt. Only the fine particles with the product are fed into the horizontal vibrating unloading centrifuge for centrifugal dehydration. During the dehydration process, the humid air in the horizontal vibrating unloading centrifuge is extracted by a vacuum pump as the wet air source of the dual-air source composite dry separator. Then, the humid air in the wet air source is pressurized by the air compressor 2 and blown into the composite dry separator, which can not only remove dust, but also increase the density of the air in the dual-air source composite dry separator to help fine particles better separate from coarse particles. Use high-speed hot air flow as the dry air source to directly dry the products in the coarse and heavy particle belts that are still vibrating in the dual-air source composite dry separator; The fine particle belt product after centrifugal dehydration and the coarse and heavy particle belt product after high-speed hot air flow drying are output to form the final dehydrated clean coal product.

[0007] Furthermore, the high-speed hot air flow is generated by the air compressor 1 and the hot air blower. The air compressor 1 collects the preheat of the surrounding equipment and further pressurizes it, and uses the hot air blower to heat and dry the coarse and heavy particle belt products.

[0008] Furthermore, the dry air source temperature is between 80°C and 120°C.

[0009] Furthermore, the horizontal vibrating unloading centrifuge is an air-suction horizontal vibrating unloading centrifuge, and the air inlet of the air-suction horizontal vibrating unloading centrifuge is arranged in a region tangentially downward in the moving direction of the screen basket, so as to facilitate the recovery of moist air.

[0010] Furthermore, the centrifugal liquid separated by the horizontal vibrating unloading centrifuge is recycled after being treated as coal slurry water.

[0011] A heavy medium cyclone clean coal dehydration system comprises a dual-air source composite dry separator, the feeding port of the dual-air source composite dry separator is connected with a vibrating screen, the dual-air source composite dry separator is a composite dry separator with a wet air source and a dry air source added thereto, wherein 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 while improving the separation effect, and the coarse and heavy particle belts on the composite dry separator are dehydrated by using the dry air flow provided by the dry air source; the fine particle belt is connected with a horizontal vibrating unloading centrifuge, the horizontal vibrating unloading centrifuge is provided with a vacuum pump capable of sucking internal humid air, the vacuum pump is connected with an air compressor 2 which uses the humid air sucked by the vacuum pump as a wet air source, and the dry air source is dry air heated and pressurized by the air compressor 1 and a hot air blower.

[0012] Furthermore, the coarse and heavy particle belt products are heated and dried using a high-speed hot air flow using a fluidized bed, a stirring device or a free-fall conveying device.

[0013] Beneficial effects: This method uses a dual-air source composite dry separator to pre-sort the coarse and heavy coal particles that do not require centrifugal dehydration, and uses hot air to achieve air drying, while the sorted fine particles are centrifugally dehydrated, effectively improving the efficiency of centrifugal dehydration, effectively reducing the feed amount of the horizontal vibrating unloading centrifuge, improving the dehydration environment of the centrifuge, improving the dehydration effect, and extending the service life of the horizontal vibrating unloading centrifuge.

[0014] This device can timely classify and separate the high-density materials after the power coal fine clean coal dehydration screen, and create a dry air environment in the centrifuge link. On the one hand, it can greatly reduce the processing volume entering the subsequent centrifuge and improve the centrifuge processing effect. On the other hand, it can provide a suitable centrifuge working environment and improve the dehydration efficiency of the fine clean coal. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Flow chart of a method for dehydrating clean coal using a heavy medium cyclone according to an embodiment of the present invention; Figure 2 Schematic diagram of a dual-air source composite dry separator in an embodiment of the present invention.

[0016] In the figure: A-vibrating screen, B-dual air source composite dry separator, C-hot air blower, D-air compressor 1, E-horizontal vibrating unloading centrifuge, F-vacuum pump, G-air compressor 2 DETAILED DESCRIPTION

[0017] The present invention will be further described below in conjunction with the accompanying drawings: like Figure 1 As shown, the present invention discloses a method for dehydrating clean coal with a heavy medium cyclone, wherein the clean coal slurry of the heavy medium cyclone is fed into a vibrating screen A; the material on the screen is fed into a dual-air source composite dry separator B to be divided into a fine particle belt and a coarse particle belt; the material in the fine particle belt is fed into an air-suction horizontal vibrating unloading centrifuge E; a vacuum pump F sucks out the humid air in the centrifuge E; the humid air is blown into the fine particle belt through an air compressor G, and the air is fed into the coarse particle belt after passing through air compressor 1D and hot air blower C; the material in the coarse particle belt is mixed with the centrifuge product to become the final product.

[0018] A heavy medium cyclone clean coal dehydration system comprises a dual-air source composite dry separator B, the inlet of which is connected to a vibrating screen A. Figure 2 As shown, the dual-air source composite dry-process separator B adds a wet air source and a dry air source on the basis of the composite dry-process separator, wherein the wet air source introduces humid air into the fine particle belt and the coarse and heavy particle belt sorting areas, effectively reducing dust while improving the sorting effect, and the coarse and heavy particle belts on the composite dry-process separator are dehydrated by the dry air flow provided by the dry air source; the fine particle belt is connected to a horizontal vibrating unloading centrifuge E, and the horizontal vibrating unloading centrifuge E is provided with a vacuum pump F that can suck the internal humid air, and the vacuum pump F is connected to a compressor 2G that uses the humid air sucked by the vacuum pump F as a wet air source, and the dry air source is dry air heated and pressurized by a compressor 1D and a hot air blower C.

[0019] like Figure 1 As shown, a method for dehydrating clean coal by a heavy medium cyclone comprises the following steps: First, the heavy medium cyclone clean coal slurry of the long flame coal is screened by the vibrating screen A, and then all the materials on the vibrating screen A are fed into the double-air source composite dry separator B. At this time, the water content in the clean coal is within 20%; The dual-air source composite dry separator B uses a vibrator to separate the input materials into two parts: fine particle products and coarse and heavy particle products through physical vibration; Only the fine particle belt products are fed into the horizontal vibrating unloading centrifuge for centrifugal dehydration. During the dehydration process, the humid air in the horizontal vibrating unloading centrifuge E is extracted by the vacuum pump F as the wet air source of the dual-air source composite dry separator B. After that, the humid air is pressurized by the air compressor 2G and blown into the sorting area of ​​the composite dry separator B to help reduce dust and improve the sorting effect of the fine particle belt. Use hot air from the dry air source to heat and dry the coarse and heavy particle belt products that are still vibrating on the double-air source composite dry separator B; The fine particle belt product after centrifugal dehydration and the coarse and heavy particle belt product after high-speed hot air flow drying are output to form the final dehydrated clean coal product.

[0020] Example: The raw coal selected by a thermal coal preparation plant is long flame coal, and the moisture of the fine clean coal is removed by combining a vibrating screen and a horizontal vibrating discharge centrifuge. All the materials on the vibrating screen A are fed into the horizontal vibrating discharge centrifuge B to become the final product, and the moisture content of the product is about 17%. In order to improve the dehydration effect, after the fine coal slurry is fed into the vibrating screen A, it is fed into the dual-air source composite dry separator B to be divided into a fine particle belt and a coarse and heavy particle part; the fine particle part is fed into the horizontal vibrating unloading centrifuge E originally installed on site through a chute; the moist air in the horizontal vibrating unloading centrifuge E is sucked by the vacuum pump F, and then pressurized by the air compressor 2G and blown into the fine particle belt of the composite dry separator B as moist air; the air passes through the air compressor 1D and the hot air blower C to form hot air and is fed into the coarse and heavy particle belt of the composite dry separator B; the coarse and heavy particle belt products are mixed with the products of the horizontal vibrating unloading centrifuge E to become the final product. The moisture content of the product is reduced by 2 percentage points compared with the previous process. At the same time, the life of the screen basket of the horizontal vibrating unloading centrifuge E is extended by more than 30%.

Claims

1. A method for dehydrating clean coal using a heavy medium cyclone, characterized in that: In the dehydration process of the existing vibrating screen (A) and the horizontal vibrating discharge centrifuge (E), a dual-air source composite dry separator (B) is added between the vibrating screen (A) and the horizontal vibrating discharge centrifuge (E), the vibrating screen (A) sends the material on the screen into the dual-air source composite dry separator (B), the dual-air source composite dry separator (B) separates the material by vibration in a humid air environment to form a fine particle band and a coarse and heavy particle band, the horizontal vibrating discharge centrifuge (E) is used to dehydrate the product of the fine particle band, the coarse and heavy particle band products in the dual-air source composite dry separator (B) are directly dried by hot air, and the dried coarse and heavy particle band products and the dehydrated fine particle band products are the final dehydrated products; the method only selects the fine particle band product for centrifugal separation, effectively prolongs the life of the horizontal vibrating discharge centrifuge (E), and improves the dehydration efficiency.

2. The method for dehydrating clean coal by using a heavy medium cyclone according to claim 1, characterized in that: The specific steps are as follows: First, the heavy medium cyclone clean coal slurry is screened using a vibrating screen (A), and then all the materials on the vibrating screen (A) are fed into a dual-air source composite dry separator (B); In the dual-air source composite dry separator (B), the material fed is separated into two parts, a fine particle band and a coarse and heavy particle band, by means of vibration in a humid air environment. During the separation process, since the larger the particle mass is, the greater the vibration amplitude is at the same vibration frequency, the particle size range of the fine particle band and the coarse and heavy particle band can be adjusted by adjusting the vibration frequency or the height of the separation partition separating the fine particle band from the coarse and heavy particle bands. Only the fine particles are fed into the horizontal vibrating unloading centrifuge for centrifugal dehydration. During the dehydration process, the humid air in the horizontal vibrating unloading centrifuge (E) is extracted by a vacuum pump (F) as the wet air source of the dual-air source composite dry separator (B). Then, the humid air in the wet air source is pressurized by the air compressor 2 (G) and blown into the composite dry separator (B). This can not only remove dust, but also increase the density of the air in the dual-air source composite dry separator (B) to help fine particles be better separated from coarse particles. Use high-speed hot air flow as the dry air source to directly dry the products in the coarse and heavy particle belts that are still vibrating in the dual-air source composite dry separator (B); The fine particle belt product after centrifugal dehydration and the coarse and heavy particle belt product after high-speed hot air flow drying are output to form the final dehydrated clean coal product.

3. The method for dehydrating clean coal by using a heavy medium cyclone according to claim 2, characterized in that: The high-speed hot air flow is generated by the air compressor 1 (D) and the hot air blower (C). The air compressor 1 (D) collects the preheat of the surrounding equipment and further pressurizes it, and uses the hot air blower (C) to heat and dry the coarse and heavy particle belt products.

4. The method for dehydrating clean coal by using a heavy medium cyclone according to claim 2, characterized in that: The dry air source temperature is between 80℃ and 120℃.

5. The method for dehydrating clean coal by using a heavy medium cyclone according to claim 2, characterized in that: The horizontal vibrating discharge centrifuge (E) is an air-suction horizontal vibrating discharge centrifuge. The air inlet of the air-suction horizontal vibrating discharge centrifuge is arranged in the area tangentially downward in the direction of the screen basket movement, so as to facilitate the recovery of moist air.

6. The method for dehydrating clean coal by using a heavy medium cyclone according to claim 2, characterized in that: The centrifugal liquid separated by the horizontal vibrating unloading centrifuge (E) is recycled after being treated as coal slurry.

7. A heavy medium cyclone clean coal dehydration system using the heavy medium cyclone clean coal dehydration method according to claim 2, characterized in that: The invention comprises a dual-air-source composite dry-process separator (B), wherein the feed port of the dual-air-source composite dry-process separator (B) is connected with a vibrating screen (A), and the dual-air-source composite dry-process separator (B) is a composite dry-process separator in which a wet air source and a dry air source are added, wherein the wet air source introduces moist air into the separation areas of the fine particle belt and the coarse and heavy particle belts, effectively reducing dust while improving the separation effect, and the coarse and heavy particle belts on the composite dry-process separator are dehydrated by using the dry air flow provided by the dry air source; the fine particle belt is connected with a horizontal vibrating unloading centrifuge (E), and the horizontal vibrating unloading centrifuge (E) is provided with a vacuum pump (F) capable of sucking the internal moist air, and the vacuum pump (F) is connected with an air compressor 2 (G) which uses the moist air sucked by the vacuum pump (F) as a wet air source, and the dry air source is dry air heated and pressurized by an air compressor 1 (D) and a hot air blower (C).

8. The heavy medium cyclone clean coal dehydration system according to claim 7, characterized in that: The coarse and heavy particle belt products are heated and dried using a high-speed hot air flow using a fluidized bed, a mixing device or a free-fall conveyor.

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