A coking coal grading and heavy medium separation process and a high-throughput heavy medium cyclone device

Abstract

This application provides a coking coal grading and heavy media separation process and a high-throughput heavy media cyclone device, belonging to the field of coal washing and processing technology. The process includes: classifying raw coal into two particle size classes, including at least coarse-grained material and coarse coal slime material; using a first heavy media cyclone to separate the coarse-grained material to obtain coarse-grained clean coal, coarse-grained middlings, and coarse-grained gangue; and using a second heavy media cyclone to separate the coarse coal slime material to obtain coarse coal slime clean coal, coarse coal slime middlings, and coarse coal slime gangue. The first media system used in the first heavy media cyclone and the second media system used in the second heavy media cyclone are independent of each other, and the densities of the two media systems are independently controlled. The coking coal grading and heavy media separation process and high-throughput heavy media cyclone device provided in this application can reduce clean coal loss.

Description

Technical Field

[0001] This application belongs to the field of coal washing and processing technology, and more specifically, it relates to a coking coal grading and heavy medium separation process and a high-throughput heavy medium cyclone device. Background Technology

[0002] Efficient coal separation is a key step in clean coal utilization, and heavy medium cyclone technology has become the mainstream separation method due to its high separation accuracy. With the depletion of high-quality coal resources and the increasing complexity of raw coal quality and the rising content of coal slime, higher demands are being placed on the adaptability, efficiency, and cost of separation processes.

[0003] Current technology has the following problems: In order to take into account the separation of a wide range of particle sizes, traditional large-diameter three-product heavy medium hydrocyclones often suffer from high feed pressure, high energy consumption, and severe equipment wear. Moreover, the separation accuracy of fine coal drops sharply, resulting in a large amount of combustible material entering the coal slurry system or flotation stage, causing loss of clean coal or increased flotation costs. Summary of the Invention

[0004] The purpose of this application is to provide a coking coal grading and heavy medium separation process and a high-throughput heavy medium cyclone device that can reduce the loss of clean coal. To achieve the above objective, the technical solution provided by this application is as follows: Firstly, a coking coal grading and heavy media separation process is provided, including: S1. Desliming step: Obtain raw coal, and perform wet desliming on the raw coal through screening equipment to obtain coarse-grained coal stream and coal slurry water stream; S2. Coal slurry water classification steps: The coal slurry water is classified by a classifying hydrocyclone to obtain underflow and overflow. The underflow is processed by a three-mass electromagnetic screen to obtain coarse coal slurry flow. S3. Coarse-grained separation step: The coarse-grained coal stream is fed into a high-throughput heavy medium cyclone device for separation to obtain coarse-grained clean coal, coarse-grained middlings coal and coarse-grained gangue. S4. Coarse-grained media recovery step: Coarse-grained clean coal, coarse-grained middlings and coarse-grained gangue are demediumed to obtain qualified suspension and dilute media suspension. The qualified suspension is returned to the combined media tank for recycling. The magnetic concentrate obtained by the dilute media suspension after being recovered by the magnetic separator is returned to the combined media tank for recycling. S5. Coarse coal slime separation step: After mixing the coarse coal slime stream with the suspension from the qualified coarse coal slime medium tank, it is fed into the coal slime heavy medium hydrocyclone for separation to obtain coarse coal slime clean coal, coarse coal slime middlings and coarse coal slime gangue. S6. Coarse coal slime media recovery and product dewatering steps: The coarse coal slime clean coal, coarse coal slime middlings and coarse coal slime gangue are diluted and magnetically separated respectively. The magnetically separated concentrate is returned to the qualified coarse coal slime media tank. The magnetically separated tailings are concentrated and dewatered to obtain clean coal products, middlings products and gangue products respectively. S7. Flotation step: The overflow from the coal slurry water classification step, the underflow from the three-mass electromagnetic screen, and the fine coal slurry water generated from the coarse coal slurry media recovery step are sent to the flotation system for separation and dewatering to obtain flotation clean coal and tailings.

[0005] In one embodiment of this application, the coarse particle separation step and the coarse coal slime separation step employ independent media systems, and the media density is independently controlled.

[0006] In one embodiment of this application, the screen aperture size of the screening equipment used in the desliming step is 1-3 mm.

[0007] In one embodiment of this application, in the coal slurry water classification step, the median particle size D50 of the magnetite powder used to prepare the qualified medium suspension is ≤15μm, and the content of -45μm particle size is ≥85%.

[0008] In one embodiment of this application, the lower limit of the coarse coal slime particle size entering the coal slime heavy medium cyclone is 0.074 mm, and the diameter of the coal slime heavy medium cyclone does not exceed 500 mm.

[0009] In one embodiment of this application, in the coarse coal slime media recovery step, the coarse coal slime concentrate, coarse coal slime middlings and coarse coal slime gangue are diluted to a mass concentration of 20% before magnetic separation.

[0010] In one embodiment of this application, in the coarse-grained media recovery step, the fine coal magnetic separation tailings are used as wetting water for the desliming step, and the middlings magnetic separation tailings and gangue magnetic separation tailings are fed into the feed material for the coal slurry water classification step.

[0011] In one embodiment of this application, in the coarse coal slime media recovery step, the coarsening point of the product after concentration and dehydration is 0.125 mm, wherein the content of +0.074 mm material does not exceed 10%.

[0012] In one embodiment of this application, the clean coal obtained from the coarse-grained separation step, the clean coal obtained from the coarse coal slime separation step, and the flotation clean coal obtained from the flotation step are mixed and homogenized to obtain the final clean coal product; the middlings obtained from the coarse-grained separation step and the middlings obtained from the coarse coal slime separation step are mixed and homogenized to obtain the final middlings product; the gangue obtained from the coarse-grained separation step and the gangue obtained from the coarse coal slime separation step are mixed and homogenized to obtain the final gangue product, or the coarse coal slime gangue is mixed into the middlings product.

[0013] Secondly, a high-throughput heavy medium cyclone device for use in coking coal grading and heavy medium separation process is provided, comprising: a first-stage cyclone and a second-stage cyclone, wherein the first-stage cyclone is a cylindrical body and the second-stage cyclone is a cylindrical-conical body, and the outlet of the first-stage cyclone and the inlet of the second-stage cyclone are connected in series; the ratio of the diameter D1 of the cylindrical section of the first-stage cyclone to the diameter D2 of the cylindrical section of the second-stage cyclone is 1.1:1-1.7:1; the equivalent diameter of the inlet of the first-stage cyclone is 0.22-0.30 times that of D1; the equivalent diameter of the inlet of the second-stage cyclone is 0.25-0.35 times that of D2, and its conical angle is 20-45°.

[0014] In one embodiment of this application, the length L1 of the cylindrical section of the first-stage hydrocyclone is 3-6 times that of D1; the length L2 of the cylindrical section of the second-stage hydrocyclone is 1.0-2.0 times that of D2.

[0015] In one embodiment of this application, the diameter d1 of the light product outlet of the first-stage hydrocyclone is 0.32-0.45 times that of D1; the diameter d2 of the medium product outlet of the second-stage hydrocyclone is 0.35-0.55 times that of D2; and the diameter d3 of the heavy product outlet is 0.2-0.45 times that of D2.

[0016] In one embodiment of this application, the inlet end face of the first-stage hydrocyclone and / or the second-stage hydrocyclone is rectangular, with the ratio of the length of its long side to the length of its short side being 1.1:1-3.0:1.

[0017] In one embodiment of this application, the hydrocyclone device has a processing capacity of 300-400 t / m²·h per unit time per unit cylinder cross-sectional area.

[0018] The beneficial effects of the technical solution provided in this application are as follows: This embodiment uses S1 wet desliming and S2 coal slime water classification to cut raw coal into three categories according to particle size: coarse-grained, coarse coal slime, and fine coal slime, instead of the traditional wide-particle-size mixed screening. Secondly, this embodiment uses a high-throughput heavy medium cyclone separator for separate separation of the coarse-grained coal stream, eliminating the need to consider the fine-grained coal separation requirements. This reduces feed pressure, energy consumption, and equipment wear, solving the problems of high energy consumption and high wear associated with traditional large-diameter cyclones. Finally, this embodiment uses a separate heavy medium cyclone separator for the separated coarse coal slime stream, which can specifically improve the separation accuracy of the coarse coal slime, fully recover combustible materials, and reduce clean coal loss. Simultaneously, only the fine coal slime water enters the flotation system, reducing the flotation feed rate and decreasing flotation reagent consumption and operating costs. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments of this application will be briefly introduced below.

[0020] Figure 1 A schematic flow diagram of a coking coal grading and heavy media separation process provided for an embodiment of this application; Figure 2 A schematic flow diagram of another coking coal grading and heavy media separation process provided in this application embodiment; Figure 3 This is a schematic diagram of a high-throughput heavy medium cyclone device provided in an embodiment of this application. Detailed Implementation

[0021] The embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the embodiments described below with reference to the accompanying drawings are exemplary descriptions for explaining the technical solutions of the embodiments of this application, and do not constitute a limitation on the technical solutions of the embodiments of this application.

[0022] Those skilled in the art will understand that, unless otherwise stated, the singular forms “a,” “an,” “the,” and “the” used herein may also include the plural forms. It should be further understood that the terms “comprising” and “including” as used in embodiments of this application mean that the corresponding feature can be implemented as the presented feature, information, data, step, operation, element, and / or component, but do not exclude implementation as other features, information, data, step, operation, element, component, and / or combinations thereof supported by the art. It should be understood that when we say that an element is “connected” or “coupled” to another element, the one element can be directly connected or coupled to the other element, or it can mean that the one element and the other element establish a connection relationship through an intermediate element. Furthermore, “connected” or “coupled” as used herein can include wireless connection or wireless coupling. The term “and / or” as used herein indicates at least one of the items defined by the term; for example, “A and / or B” can be implemented as “A,” or as “B,” or as “A and B.” When describing multiple (two or more) items, if the relationship between the multiple items is not explicitly defined, the multiple items can refer to one, several or all of the multiple items. For example, the description of "parameter A includes A1, A2, A3" can be implemented as parameter A includes A1 or A2 or A3, or it can be implemented as parameter A includes at least two of the three items A1, A2 and A3.

[0023] To make the objectives, technical solutions, and advantages of this application clearer, the following description will be provided in conjunction with the accompanying drawings and specific embodiments.

[0024] This application provides a coking coal grading and heavy media separation process, such as... Figure 1 As shown, the method may include: S1-S7.

[0025] S1. Desliming step: Obtain raw coal, and perform wet desliming on the raw coal through screening equipment to obtain coarse-grained coal stream and coal slurry water stream; S2. Coal slurry water classification steps: The coal slurry water is classified by a classifying hydrocyclone to obtain underflow and overflow. The underflow is processed by a three-mass electromagnetic screen to obtain coarse coal slurry flow. S3. Coarse-grained separation step: The coarse-grained coal stream is fed into a high-throughput heavy medium cyclone device for separation to obtain coarse-grained clean coal, coarse-grained middlings coal and coarse-grained gangue. S4. Coarse-grained media recovery step: Coarse-grained clean coal, coarse-grained middlings and coarse-grained gangue are demediumed to obtain qualified suspension and dilute media suspension. The qualified suspension is returned to the combined media tank for recycling. The magnetic concentrate obtained by the dilute media suspension after being recovered by the magnetic separator is returned to the combined media tank for recycling. S5. Coarse coal slime separation step: After mixing the coarse coal slime stream with the suspension from the qualified coarse coal slime medium tank, it is fed into the coal slime heavy medium hydrocyclone for separation to obtain coarse coal slime clean coal, coarse coal slime middlings and coarse coal slime gangue. S6. Coarse coal slime media recovery and product dewatering steps: The coarse coal slime clean coal, coarse coal slime middlings and coarse coal slime gangue are diluted and magnetically separated respectively. The magnetically separated concentrate is returned to the qualified coarse coal slime media tank. The magnetically separated tailings are concentrated and dewatered to obtain clean coal products, middlings products and gangue products respectively. S7. Flotation step: The overflow from the coal slurry water classification step, the underflow from the three-mass electromagnetic screen, and the fine coal slurry water generated from the coarse coal slurry media recovery step are sent to the flotation system for separation and dewatering to obtain flotation clean coal and tailings.

[0026] In this embodiment, the S1 desliming step refers to the process where raw coal enters a wet screening device (desliming screen) and is deslimed by water washing and screening, resulting in a coarse coal flow above the screen and a coal slime water flow below the screen. This step is used to pre-cut the raw coal according to particle size, separate coarse coal from fine coal slime, and avoid the problems of high energy consumption and poor fine particle separation caused by wide particle size mixing.

[0027] The S2 coal slime water classification step refers to first classifying the S1 coal slime water flow through a classifying hydrocyclone, with the underflow entering a three-mass electromagnetic screen for further desliming and dewatering, ultimately yielding a coarse coal slime flow; the overflow from the hydrocyclone and the underflow from the electromagnetic screen are fine coal slime water, which is temporarily stored for flotation to purify the coarse coal slime, removing ultrafine high-ash mud of -0.074mm to avoid interference with the coarse coal slime classification; all qualified coarse coal slime (+0.074mm) is introduced into the classification system to achieve full-volume classification of coarse coal slime.

[0028] The S3 coarse-grained separation step refers to sending the coarse-grained coal stream from S1 into a high-throughput, three-product heavy medium cyclone device to separate coarse clean coal, coarse middlings, and coarse gangue in one pass. This method is based on the high throughput, low energy consumption, and high precision of a dedicated coarse-grained cyclone to solve the problems of high feed pressure, high wear, and fine-grained separation failure in traditional large-diameter cyclones.

[0029] The S4 coarse-grained media recovery step involves passing the three coarse-grained products through a two-stage desliming process using an arc screen and a desliming screen to separate a qualified suspension (which is directly recycled back to the coarse-grained media tank) and a dilute media suspension (which is recovered by a magnetic separator, with the magnetic concentrate returned to the coarse-grained media tank). This achieves a closed-loop circulation of the coarse-grained media, allowing for the reuse of magnetite powder and reducing media consumption. Simultaneously, it achieves a closed-loop water system with no external discharge.

[0030] The S5 coarse coal slime separation step involves mixing the coarse coal slime stream from S2 with the qualified coarse coal slime medium suspension and feeding it into a fine coal slime heavy medium hydrocyclone to separate coarse coal slime into fine coal, middlings, and gangue. The small-diameter hydrocyclone provides high centrifugal force, achieving deep fine separation of coarse coal slime with a separation accuracy far superior to traditional processes, thus avoiding the generation of secondary coal slime due to over-crushing of coarse coal slime.

[0031] The S6 coarse coal slime media recovery and product dewatering process involves first diluting the three coarse coal slime products to a mass concentration of 20%, then subjecting them to magnetic separation using a wide-particle-size magnetic separator. The magnetic concentrate is returned to the qualified coarse coal slime media tank, while the magnetic separation tailings are dewatered using a thickening hydrocyclone and a three-mass electromagnetic / high-frequency screen to obtain the final coarse coal slime product. The aim is to achieve independent recovery and recycling of the coarse coal slime media and to dewater the coarse coal slime product to commercial coal standards, thus completing the full recovery of coarse coal slime.

[0032] The S7 flotation step involves feeding the S2 stage overflow, the underflow from the three-mass electromagnetic screen, and the -0.074mm fine coal slime water generated from the S6 coarse coal slime recovery into the flotation system for separation and dewatering to obtain flotation clean coal and tailings. This completes the final recovery of fine-grained coal slime, achieving closed-loop separation of all particle sizes (0~coarse) of raw coal and maximizing the clean coal recovery rate.

[0033] As can be seen from the above, this embodiment of the application uses S1 wet desliming and S2 coal slime water classification to cut raw coal into three categories according to particle size: coarse-grained, coarse coal slime, and fine coal slime, instead of the traditional wide-particle-size mixed screening. Secondly, this embodiment uses a high-throughput heavy medium cyclone separator for separate separation of the coarse-grained coal stream, without needing to consider the separation requirements of fine-grained coal, which can reduce the feed pressure, reduce energy consumption and equipment wear, and solve the problems of high energy consumption and high wear of traditional large-diameter cyclones. Finally, this embodiment uses a separate coal slime heavy medium cyclone separator for separation of the separated coarse coal slime stream, which can specifically improve the separation accuracy of coarse coal slime, fully recover the combustibles, and reduce the loss of clean coal; at the same time, only fine coal slime water enters the flotation system, which reduces the flotation feed amount and reduces the consumption of flotation reagents and operating costs.

[0034] In one embodiment of this application, the coking coal grading and heavy media separation process can also be implemented in the following manner, please refer to... Figure 2 The system employs a three-stage classification and separation architecture: coarse-grained heavy medium separation, coarse coal slime heavy medium separation, and fine coal slime flotation. It is equipped with two independent heavy medium circulation systems and a fully closed-loop circulating water system to achieve efficient separation of raw coal across all particle sizes. The specific process steps are as follows: Step 1: Raw coal pretreatment and wet desliming The raw coal is first classified by a grading screen. Larger pieces are then manually sorted to remove impurities such as debris and large pieces of gangue. The sorted material is then fed into a grading crusher to break down the oversized coal to the required size for washing. After crushing, the material is fed into a wet desliming screen with a water spray pattern (1-3mm aperture) for wet desliming. After wet desliming, the raw coal is separated into two streams: the oversize (+1-3mm coarse coal) stream, which is sent to the subsequent coarse-grained heavy media separation system; and the undersize (-1-3mm coal slime) stream, which is sent to the subsequent coal slime water classification and coarse coal slime preparation system. This step, by pre-cutting the particle size, separates coarse coal from fine coal slime, avoiding the industry pain points of high hydrocyclone feed pressure, high energy consumption, and poor fine particle separation accuracy caused by wide-size mixing, thus laying the foundation for grading and separation.

[0035] Step 2: Coal slime water classification and coarse coal slime preparation The coal slime water flowing under the desliming screen is sent to a coal slime thickening hydrocyclone for classification. The classification particle size control point of the coal slime thickening hydrocyclone is ≤0.074mm, and the classification efficiency is ≥85%. The underflow of the hydrocyclone (coarse coal slime component) is sent to a three-mass composite electromagnetic screen for deep desliming and dewatering, ultimately obtaining two types of materials: the overflow from the three-mass composite electromagnetic screen: +0.074mm qualified coarse coal slime, which is used as feed for coarse coal slime heavy media separation; the overflow from the coal slime thickening hydrocyclone and the underflow from the three-mass composite electromagnetic screen: -0.074mm ultrafine high-ash fine mud, which is collected as fine coal slime water and sent to the subsequent flotation system. This step, through the combination of the classifying hydrocyclone and the electromagnetic screen, eliminates the interference of ultrafine high-ash fine mud on coarse coal slime separation, purifies qualified coarse coal slime, and provides qualified feed for the full-volume separation of coarse coal slime.

[0036] Step 3: Coarse-grained heavy medium separation The +1~3mm coarse-grained coal stream from the desliming screen is mixed with the heavy medium suspension from the qualified coarse-grained medium tank and then fed into a high-throughput, three-product heavy medium hydrocyclone for separation. This heavy medium hydrocyclone is the core separation device, employing a series structure of a cylindrical section and a cylindrical-conical section. The core structural parameters are: the ratio of the diameter D1 of the first cylindrical section to the diameter D2 of the second cylindrical section is 1.1:1~1.7:1, and the unit processing capacity can reach 300~400 t / m². h; The heavy medium suspension was prepared using magnetite powder, with a median particle size D of the magnetite powder.50 The content of particles ≤15μm and -45μm is ≥85%. Under the action of centrifugal force, the coarse-grained coal flows through a high-throughput three-product heavy medium cyclone separator and is separated into three products in one pass: coarse clean coal, coarse middlings, and coarse gangue, completing the efficient separation of coarse particles. This step uses an independent first heavy medium system, which can be individually adjusted in terms of separation density and is completely isolated from the subsequent coarse coal slime separation system to avoid mutual interference.

[0037] Step 4: Coarse-grained media recovery and product dehydration The coarse-grained clean coal, coarse-grained middlings, and coarse-grained gangue separated by the high-throughput three-product heavy medium cyclone are sent to corresponding desliming screens for two-stage desliming treatment: the qualified suspension under the desliming screen is directly returned to the coarse-grained stage combined medium tank for recycling; the dilute medium suspension on the desliming screen is sent to the clean coal magnetic separator, middlings magnetic separator, and gangue magnetic separator for medium recovery, and all magnetic concentrate is returned to the coarse-grained stage combined medium tank for recycling; the tailings from the clean coal magnetic separation are used as wetting water for the desliming screen, while the tailings from the middlings and gangue magnetic separation are returned to the coal slime water tank for recycling in the coal slime water classification process. The deslimed coarse-grained clean coal and coarse-grained middlings are dewatered by the clean coal centrifuge and middlings centrifuge, respectively, to obtain dewatered coarse-grained clean coal and coarse-grained middlings products; the coarse-grained gangue is directly discharged as coarse-grained gangue product after desliming. This step enables closed-loop circulation of coarse-grained heavy media, significantly reducing the consumption of magnetite powder, while simultaneously achieving internal circulation of the water system.

[0038] Step 5: Coarse coal slime heavy media separation The +0.074mm qualified coarse coal slime stream, purified by a three-particle composite electromagnetic screen, is mixed with a heavy medium suspension from a qualified coarse coal slime medium tank and then fed into a fine-grained coal slime heavy medium hydrocyclone for separation. This coal slime heavy medium hydrocyclone has a diameter ≤500mm, a feed particle size limit of 0.074mm, and a separation accuracy Ep value of 0.04~0.08g / cm³, enabling deep fine-grained separation of coarse coal slime. Under the action of a high centrifugal force field, the coarse coal slime stream is separated into three products—coarse coal slime concentrate, coarse coal slime middlings, and coarse coal slime gangue—by the fine-grained coal slime heavy medium hydrocyclone. This step uses an independent second heavy medium system, which allows for independent control of the separation density and is completely independent of the coarse particle separation system, meeting the requirements for high-precision separation of coarse coal slime.

[0039] Step 6: Coarse coal slime media recovery and product dewatering The coarse coal slime concentrate, middlings, and gangue separated by the high-quality coal slime heavy medium hydrocyclone are diluted with dilution water to a mass concentration of 20% and then fed into corresponding coarse coal slime magnetic separators (coarse coal slime concentrate magnetic separator, coarse coal slime middlings magnetic separator, and coarse coal slime gangue magnetic separator) for magnetic separation and recovery. All magnetic concentrate is returned to the qualified medium tank for recycling, achieving a closed-loop circulation of the heavy medium in the coarse coal slime. The tailings from the magnetic separation are fine coal slime water, which is incorporated into the flotation feed system. The coarse coal slime products after magnetic separation are sent to corresponding coarse coal slime dewatering screens for dewatering. The coarse coal slime concentrate is then sent to a coal slime centrifuge for secondary dewatering, ultimately yielding dewatered coarse coal slime concentrate, middlings, and gangue products. The coarsening point of the dewatered products is 0.125mm, and the content of +0.074mm material does not exceed 10%, meeting the quality requirements for commercial coal.

[0040] Step 7: Fine coal slime flotation and tailings treatment All the -0.074mm fine coal slime water obtained by combining the overflow from the coal slime thickening hydrocyclone, the underflow from the three-mass composite electromagnetic screen, and the tailings from the coarse coal slime magnetic separation is sent to a flotation machine for separation, separating flotation clean coal and tailings: (1) The flotation concentrate is fed into the flotation concentrate bucket and then dewatered by the coal filter press to obtain the dewatered flotation concentrate product; (2) The tailings are fed into a thickener for thickening. The underflow from the thickener is dewatered by a tailings filter press to obtain tailings slime, which can be discharged or utilized. The overflow from the thickener is reused as circulating water. In this step, since the coarse coal slime has been fully separated, the flotation feed amount is significantly reduced compared to the traditional process, which can significantly reduce the consumption of flotation reagents and operating costs.

[0041] This process employs a fully closed-loop circulating water system. All return water generated during the processes (including magnetic separation tailings, desliming screen return water, filter press filtrate, etc.) is collected into the circulating water system and reused for spraying and dilution in each process. Only a small amount of clean water is added to maintain the system's water balance, achieving zero discharge of production wastewater. The final product is integrated as follows: Final clean coal: coarse-grained clean coal, coarse coal slime clean coal, and flotation clean coal; final middlings: coarse-grained middlings and coarse coal slime middlings, which can be selectively mixed with coarse coal slime gangue according to production needs; final gangue: coarse-grained gangue and coarse coal slime gangue.

[0042] As can be seen from the above, the embodiments of this application adopt a three-stage classification and separation architecture: coarse-grained heavy medium separation, coarse coal slime heavy medium separation, and fine coal slime flotation. Through wet desliming of raw coal and classification of coal slime water, the raw coal is accurately separated according to particle size, avoiding the problems of high feed pressure, high energy consumption, and severe equipment wear caused by wide-particle-size mixing. Secondly, the coarse-grained coal stream is separated separately using a high-throughput heavy medium cyclone, ensuring processing capacity while reducing system energy consumption and equipment wear. Thirdly, the coarse coal slime, after purification, enters the coal slime heavy medium cyclone separately for separation, which can improve the separation accuracy of fine coal particles, reduce combustible material loss, and reduce clean coal loss. Fourthly, the classification medium recovery achieves closed-loop circulation of heavy media, reducing medium loss. Finally, in this embodiment, only fine coal slime water enters the flotation system, which can reduce the flotation feed amount and reagent consumption, and reduce flotation costs.

[0043] In one embodiment of this application, the equipment used in the process includes: a desliming screen, a dedicated high-throughput three-product heavy medium hydrocyclone (high-throughput heavy medium hydrocyclone device), a classifying hydrocyclone, a three-mass electromagnetic screen, a fine coarse coal slime heavy medium hydrocyclone, a magnetic separator, a wide-particle-size magnetic separator, a desliming screen, a centrifuge, a coal slime centrifuge, a thickening hydrocyclone, a high-frequency screen, a flotation machine, a thickener, and a filter press; the process includes desliming; coal slime water thickening and classification; coarse coal separation; coarse product desliming and dewatering; coarse coal medium circulation and recovery; coarse coal slime separation; coarse coal slime product desliming, dewatering, and recovery; and fine coal flotation and recovery.

[0044] More specifically, in this embodiment, the coking coal grading and heavy media separation process can also be implemented in the following ways: a. Desliming: Raw coal is wet deslimed through a 2mm desliming screen, separating it into +2mm coarse coal particles and -2mm coal slurry. The material under the desliming screen enters the coal slurry bucket, while the raw coal over the desliming screen enters the set coarse coal separation system.

[0045] b. Coal slime water concentration and classification: The material entering the coal slime bucket in step a is pumped under certain pressure into a classifying hydrocyclone for classification. The underflow from the hydrocyclone enters a three-mass electromagnetic screen 1 for desliming and dewatering, and then becomes coarse coal slime that enters the coal slime mixing bucket. The overflow from the classifying hydrocyclone and the underflow from the three-mass electromagnetic screen 1 enter the flotation system. The overflow from the classifying hydrocyclone and the three-mass electromagnetic screen control the classification particle size point to 0.074mm, and the classification efficiency is not less than 85%.

[0046] c. Coarse Coal Separation: Coarse coal particles exceeding 2mm from the desliming screen in step a are separated into three product streams: coarse clean coal stream, coarse middlings stream, and coarse gangue stream. The hydrocyclone's structural parameters are as follows: the diameter ratio of the first-stage hydrocyclone (D1 = Ф1000mm, including angle) to the second-stage hydrocyclone (D2 = Ф800mm) is 1.25:1. The first-stage hydrocyclone is cylindrical with a length L1 = 4200mm, and the equivalent diameter of the inlet is 0.255 times the diameter D1. The second-stage hydrocyclone is cylindrical-conical with a length L2 = 1000mm, which is 1.25 times the diameter D2. The equivalent diameter of the second-stage hydrocyclone is 0.285 times the diameter D2, and the conical angle is 25 degrees.

[0047] d. Dewatering and demediuming of coarse products: The coarse clean coal stream and coarse middlings stream obtained in step c are dewatered and demediumed by demediuming screen and centrifuge, respectively, to form clean coal 1 and middlings 1 products. The gangue stream is dewatered and demediumed by demediuming screen to form gangue 1 product.

[0048] e. Coarse Coal Medium Circulation and Recovery: The three products obtained in step c—coarse clean coal stream, coarse middlings stream, and coarse gangue stream—are fed into two stages of desliming equipment—an arc screen and a desliming screen—for processing, respectively, to obtain qualified suspensions and dilute medium suspensions. The qualified suspensions are directly recycled into a combined medium tank for reuse, with a portion of the qualified medium suspension from the arc screen of clean coal diverted. The obtained coarse clean coal diverted stream is mixed with the coarse clean coal dilute medium suspension and fed into a clean coal magnetic separator for recovery. The middlings dilute medium suspension and gangue dilute medium suspension are fed into magnetic separators for recovery, respectively. The magnetic concentrate recovered by the magnetic separator is recycled into the combined medium tank. The tailings from the clean coal magnetic separation are used as wetting water for the desliming screen. The tailings from the middlings magnetic separation and the gangue magnetic separation are fed into the coal slime water tank in step b.

[0049] f. Coarse coal slime separation: A suspension inlet pipe is installed on the coal slime mixing cylinder in step b. The qualified medium suspension of coarse coal slime is pumped in by a pump. The material in the mixing cylinder is pumped into the heavy medium hydrocyclone of the fine coal slime under a certain pressure for separation, resulting in clean coal stream, middlings coal stream and gangue stream.

[0050] g. Dewatering, desliming, and recovery of coarse coal slime products: The clean coal stream, middlings stream, and gangue stream obtained in step f are diluted to a concentration of 20% and then enter the wide-particle-size clean coal magnetic separator, wide-particle-size middlings magnetic separator, and wide-particle-size gangue magnetic separator, respectively. The magnetic concentrate is returned to the qualified medium suspension tank of coarse coal slime. The tailings from the wide-particle-size clean coal magnetic separator are dewatered by a thickening hydrocyclone 1. The underflow from the thickening hydrocyclone 1 enters the three-mass electromagnetic screen 2 for desliming and dewatering. The material on the electromagnetic screen 2 enters the coal slime centrifuge for dewatering and recovery, forming clean coal product 2. The tailings from the wide-particle-size middlings magnetic separator are dewatered by a thickening hydrocyclone 2. The underflow from the thickening hydrocyclone 2 enters the high-frequency screen 1 for dewatering, forming middlings product 2. The tailings from the wide-particle-size gangue magnetic separator are dewatered by a thickening hydrocyclone 3. The underflow from the thickening hydrocyclone 3 enters the high-frequency screen 2 for dewatering, forming gangue product 2. The overall coarse particle size of the overflow from each hydrocyclone and the underflow from the electromagnetic screen and high-frequency screen is 0.125mm, of which the +0.074mm material does not exceed 10%.

[0051] h. Fine coal flotation and recovery: The -0.074mm fine coal slurry generated in steps b and g enters the flotation system, and after separation and dewatering, clean coal 3 and tailings products are obtained.

[0052] i. Clean coal 1, clean coal 2, and clean coal 3 are mixed and homogenized to obtain the final clean coal product; middlings 1 and middlings 2 are mixed and homogenized to obtain the final middlings product. Gangue 2 and gangue 1 are mixed and homogenized to obtain the final gangue product.

[0053] The high-throughput three-product heavy medium hydrocyclone of this invention is a specialized device; the coal slime heavy medium hydrocyclone and wide-particle-size magnetic separator are improved devices; the classification equipment, demediuming equipment, thickening equipment, dewatering equipment, flotation equipment, etc. are general-purpose equipment. After industrial application of this invention's process, compared with the traditional heavy medium coal preparation process for similar coal quality, the processing capacity of the heavy medium hydrocyclone of the same diameter in the separation stage is increased by 50%-80%, the energy consumption per ton of coal in the separation stage is reduced by 35%, the lower limit of coarse coal slime separation is reduced to 0.074mm, the separation accuracy Ep value reaches 0.06g / cm3, the clean coal recovery rate is increased by 0.4-0.7%, the overall quantity efficiency is increased by 1-1.5%, and the medium consumption is reduced by 20%.

[0054] In one embodiment of this application, reference is made to Figure 3 The high-flux heavy medium cyclone device adopts a structure consisting of a cylindrical cyclone section and two cylindrical-conical cyclones connected in series.

[0055] One section of the hydrocyclone adopts a constant-diameter cylindrical structure with a length of L1 and a diameter of D1. Section 1 feed inlet: Located on the side wall of the cylinder, it is a rectangular feed inlet (size A×B, length-to-width ratio 1.1:1~3.0:1), used for tangentially feeding of coarse-grained coal flow and heavy medium suspension; A and B can be set according to actual needs.

[0056] Light product discharge port: Located at the axial overflow end of the cylinder, it is a circular overflow port (diameter d1) used to discharge the coarse fine coal (low density light product) separated in the first stage. First and second stage connecting pipe (second stage feed port): Located at the underflow end of the cylinder, it is a series connection structure of two hydrocyclones, which introduces the mixture of medium and heavy products from the underflow of the first stage into the second stage hydrocyclone.

[0057] The two-stage hydrocyclone adopts a combination structure of cylindrical and conical sections, with a total length of L1, a diameter of D1 for the cylindrical section, and a cone angle θ of 20°-45° for the conical section. The intermediate product outlet is located at the axial overflow end of the cylindrical section and is a circular overflow port (diameter d3) used to discharge the coarse middlings (medium-density intermediate product) separated in the second stage; the heavy product outlet is located at the bottom flow end of the conical section and is a circular bottom flow port (diameter d2) used to discharge the coarse gangue (high-density heavy product) separated in the second stage.

[0058] The ratio of the diameter D1 of the first cylindrical section to the diameter D2 of the second cylindrical section is 1.1:1 to 1.7:1, ensuring a reasonable match between the centrifugal force fields of the two sections and balancing processing capacity and sorting accuracy. The equivalent diameter of the feed inlet of the first section is 0.22 to 0.30 times that of D1, and the equivalent diameter of the feed inlet of the second section is 0.25 to 0.35 times that of D2, adapting to the needs of high-throughput feeding and avoiding blockage. The cone angle θ of the second conical section is 20° to 45°, ensuring efficient discharge of heavy products and avoiding gangue accumulation. The unit processing capacity can reach 300 to 400 t / m²·h, enabling large-scale sorting under low feed pressure, reducing energy consumption and equipment wear.

[0059] In this embodiment, the mixture of coarse-grained coal and heavy medium suspension enters the cylindrical section of a hydrocyclone tangentially through a feed inlet. Under the centrifugal force field generated by high-speed rotation: low-density clean coal gathers towards the center of the cylinder and is discharged through the light product outlet, completing the first separation of coarse-grained clean coal; the mixture of medium and heavy products moves towards the cylinder wall and enters the second-stage hydrocyclone through the first and second-stage connecting pipes; under the secondary centrifugal force field of the two-stage cylinder and conical structure, medium-density middlings gathers towards the center and is discharged through the middlings outlet; high-density gangue moves towards the cylinder wall and is discharged through the heavy product outlet; finally, coarse-grained clean coal, coarse middlings, and coarse gangue are separated in one step, achieving efficient separation of three products at the coarse-grained level.

[0060] Compared to traditional single-stage large-diameter hydrocyclones, it can achieve high-throughput separation at lower feed pressure, reducing energy consumption and equipment wear; at the same time, through two independent centrifugal force fields for classification, it improves the separation accuracy of coarse particles, avoids the loss of clean coal, and is suitable for the high-precision separation requirements of coking coal.

[0061] It should be understood that although arrows indicate various operation steps in the flowcharts of this application's embodiments, the order in which these steps are implemented is not limited to the order indicated by the arrows. Unless explicitly stated herein, in some implementation scenarios of this application's embodiments, the implementation steps in each flowchart can be executed in other orders as required. Furthermore, some or all steps in each flowchart, based on the actual implementation scenario, may include multiple sub-steps or multiple stages. Some or all of these sub-steps or stages can be executed at the same time, and each sub-step or stage can also be executed at different times. In scenarios where execution times differ, the execution order of these sub-steps or stages can be flexibly configured according to requirements, and this application's embodiments do not limit this.

[0062] The above are only optional implementation methods for some implementation scenarios of this application. It should be noted that for those skilled in the art, other similar implementation methods based on the technical concept of this application, without departing from the technical concept of this application, also fall within the protection scope of the embodiments of this application.

Claims

1. A coking coal grading and heavy media separation process, characterized in that, include: S1. Desliming step: Obtain raw coal, and perform wet desliming on the raw coal through screening equipment to obtain coarse-grained coal stream and coal slurry water stream; S2, Coal slime water classification step: The coal slime water is classified by a classifying hydrocyclone to obtain underflow and overflow. The underflow is processed by a three-mass electromagnetic screen to obtain coarse coal slime flow. S3. Coarse-grained separation step: The coarse-grained coal stream is fed into a high-throughput heavy medium cyclone device for separation to obtain coarse-grained clean coal, coarse-grained middlings coal and coarse-grained gangue. S4. Coarse-grained media recovery step: The coarse-grained clean coal, coarse-grained middlings and coarse-grained gangue are subjected to demediation treatment to obtain qualified suspension and dilute media suspension. The qualified suspension is returned to the combined media tank for recycling, and the magnetic concentrate obtained by the dilute media suspension after being recovered by the magnetic separator is returned to the combined media tank for recycling. S5. Coarse coal slime separation step: After mixing the coarse coal slime stream with the suspension from the qualified coarse coal slime medium tank, it is fed into the coal slime heavy medium hydrocyclone for separation to obtain coarse coal slime clean coal, coarse coal slime middlings and coarse coal slime gangue. S6. Coarse coal slime media recovery and product dewatering steps: The coarse coal slime clean coal, coarse coal slime middlings and coarse coal slime gangue are diluted and magnetically separated respectively. The magnetically separated concentrate is returned to the coarse coal slime qualified media tank. The magnetically separated tailings are concentrated and dewatered to obtain clean coal products, middlings products and gangue products respectively. S7. Flotation step: The overflow from the coal slurry water classification step, the underflow from the three-mass electromagnetic screen, and the fine coal slurry water generated from the coarse coal slurry media recovery step are sent to the flotation system for separation and dewatering to obtain flotation clean coal and tailings.

2. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, The coarse particle separation step and the coarse coal slime separation step use independent media systems, and the media density is independently controlled.

3. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, The screen size of the screening equipment used in the desliming step is 1-3 mm.

4. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, In the coal slurry water classification step, the median particle size D50 of the magnetite powder used to prepare the qualified medium suspension is ≤15μm, and the content of -45μm particle size is ≥85%.

5. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, The lower limit of the coarse coal slime particle size entering the coal slime heavy medium cyclone is 0.074 mm, and the diameter of the coal slime heavy medium cyclone does not exceed 500 mm.

6. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, In the coarse coal slime media recovery step, the coarse coal slime concentrate, coarse coal slime middlings, and coarse coal slime gangue are diluted to a mass concentration of 20% before magnetic separation.

7. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, In the coarse-grained media recovery step, the fine coal magnetic separation tailings are used as wetting water for the desliming step, and the middlings magnetic separation tailings and gangue magnetic separation tailings are fed into the feed material of the coal slurry water classification step.

8. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, In the coarse coal slime media recovery step, the coarsening point of the product after concentration and dehydration is 0.125mm, of which the content of +0.074mm material does not exceed 10%.

9. The coking coal grading and heavy media separation process as described in claim 1, characterized in that, The clean coal obtained from the coarse-grained separation step, the clean coal obtained from the coarse coal slime separation step, and the flotation clean coal obtained from the flotation step are mixed and homogenized to obtain the final clean coal product; the middlings obtained from the coarse-grained separation step and the middlings obtained from the coarse coal slime separation step are mixed and homogenized to obtain the final middlings product; the gangue obtained from the coarse-grained separation step and the gangue obtained from the coarse coal slime separation step are mixed and homogenized to obtain the final gangue product, or the coarse coal slime gangue is mixed into the middlings product.

10. A high-throughput heavy medium cyclone apparatus for implementing the process described in any one of claims 1-9, characterized in that, include: The device comprises a first-stage hydrocyclone and a second-stage hydrocyclone. The first-stage hydrocyclone is a cylindrical body, and the second-stage hydrocyclone is a cylindrical-conical body. The outlet of the first-stage hydrocyclone is connected in series with the inlet of the second-stage hydrocyclone. The ratio of the diameter D1 of the cylindrical section of the first-stage hydrocyclone to the diameter D2 of the cylindrical section of the second-stage hydrocyclone is 1.1:1-1.7:

1. The equivalent diameter of the inlet of the first-stage hydrocyclone is 0.22-0.30 times that of D1. The equivalent diameter of the inlet of the second-stage hydrocyclone is 0.25-0.35 times that of D2, and its conical angle is 20-45°.

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