A full-size heavy medium separation process for power coal coarse slime and a slime heavy medium cyclone

Abstract

The present application relates to the technical field of coal separation, and provides a power coal coarse slime full particle size heavy medium separation process and slime heavy medium cyclone, wherein the separation process comprises the following steps: S1: performing online particle size analysis and ash content detection on coarse slime, setting a separation density target value and an initial value of feeding pressure according to the detection results, and preparing a feeding suspension; S2: feeding the feeding suspension into the slime heavy medium cyclone for separation, to obtain a clean coal product stream and a tail coal product stream; S3: respectively performing water supplement dilution, magnetic separation, concentration grading and dehydration treatment on the clean coal product stream and the tail coal product stream, to obtain coarse particle products and fine particle products; and S4: returning overflow, undersize water and filtrate generated in the separation process to a thickener for treatment, and when the operation load of a clean coal thickener is continuously higher than 85%, switching the clean coal filter press filtrate to a circulating water pool, to realize closed water circulation of the system. The present application realizes efficient full particle size separation of coarse slime.

Description

Technical Field

[0001] This invention relates to the field of coal sorting technology, specifically to a full-size heavy medium separation process for coarse coal slime in power coal and a heavy medium hydrocyclone for coal slime. Background Technology

[0002] For the separation and recovery of coarse coal slime in the thermal coal sector, current technologies revolve around slime reduction and deep dewatering. Slime reduction and desliming processes reduce slime generation through source reduction, mid-process recovery, and end-stage quality improvement, such as the use of intelligent dry separation for lump coal and deep dry screening for fine coal. In terms of deep dewatering, ultra-high pressure dewatering technology has become a key breakthrough, and some coal preparation plants have improved the recovery rate and quality of coarse coal slime by adding equipment such as spiral separators and centrifuges. Furthermore, intelligent technologies such as machine vision and robotic arm intelligent separation systems are being gradually applied.

[0003] However, existing technologies still face significant challenges: First, wet separation easily leads to gangue sludge formation, with high-ash fine mud contaminating coarse coal slime products, resulting in high ash content and reduced calorific value; second, the process system is not adaptable enough to fluctuations in raw coal quality, leading to increased media consumption and decreased separation efficiency; third, some coal preparation plants have problems such as poor performance of key equipment and high energy consumption of dewatering equipment, and the ability to refine management and predict coal quality needs to be improved. Summary of the Invention

[0004] To overcome the above-mentioned defects, embodiments of the present invention provide a full-size heavy medium separation process for coarse coal slime and a heavy medium hydrocyclone for coal slime, which solves the technical problems of easy mudification of gangue, high ash fine mud contamination of clean coal products leading to high ash content and reduced calorific value during wet separation of coarse coal slime in the prior art, as well as the small processing capacity, high separation lower limit, poor adaptability to fluctuations in feed coal quality, large medium consumption and high system energy consumption of traditional separation equipment.

[0005] According to one aspect, at least one embodiment of the present invention provides a whole-size heavy medium separation process for coarse coal slime of thermal coal, comprising the following steps: S1: Perform online particle size analysis and ash content testing on the coarse coal slime, and set the target value of the sorting density and the initial value of the feed pressure based on the test results; prepare the coarse coal slime into a coal slurry, mix it with qualified medium in a mixing tank, and obtain the feed suspension; S2: The feed suspension is fed into a coal slime heavy medium cyclone separator for separation to obtain clean coal product stream and tailings product stream; S3: The clean coal product stream and the tailings product stream are respectively subjected to water dilution, magnetic separation, concentration and classification and dewatering treatment to obtain coarse product and fine product respectively; S4: The overflow, underflow, and filtrate generated during the sorting process are returned to the thickener for treatment. When the operating load of the coal thickener is continuously higher than 85%, the filtrate from the coal filter press is switched to the circulating water tank to realize the closed-loop water circulation of the system.

[0006] According to one embodiment provided in this application, the concentration of the coal slurry in S1 is not less than 25%, and the density of the feed suspension is 1.40 to 1.80 g / cm3.

[0007] According to one embodiment of this application, in step S3, the coarse product is dewatered by a high-frequency screen and then by centrifugal dewatering, and the fine product is dewatered by pressure filtration; the coarse product and the fine product are independently recovered or mixed to form the final clean coal product.

[0008] According to one embodiment of this application, the method further includes an intelligent control step: based on the detection data of the densitometer and pressure sensor, and combined with the information on the content of magnetic materials and coal slime obtained by other sensors, the medium addition valve, the water supply valve and the medium diversion ratio are adjusted to stabilize the sorting density control accuracy within ±0.002 g / cm³. The density meter is installed in the outlet pipe of the mixing pump, and the pressure sensor is installed in the inlet of the hydrocyclone.

[0009] According to one embodiment of this application, the intelligent control step further includes: when the online ash analyzer detects that the deviation of the clean coal ash content from the target value reaches ±0.5%, adjusting the water replenishment amount in the mixing tank to change the sorting density; If the ash content of the clean coal still does not meet the standard after adjusting the separation density, then adjust the feed pressure of the coal slime heavy medium cyclone. When the fine mud content in the feed exceeds the preset range, adjust the sorting density and feed pressure.

[0010] According to one embodiment provided in this application, the preset range of the change in fine mud content is specifically that the absolute change in the content of -0.074mm particle size exceeds ±5 percentage points.

[0011] According to one embodiment provided in this application, the feed pressure of the coal slime heavy medium cyclone in S2 is not greater than 0.15 MPa.

[0012] This invention provides a full-size heavy medium separation process for coarse coal slime in power coal. Compared with existing technologies, this process pre-sets the separation density and feed pressure through online particle size analysis and ash content detection, enabling the process to adaptively adjust to coal quality fluctuations. This effectively suppresses the contamination of clean coal products by high-ash fine slime, reduces the ash content of clean coal, and increases its calorific value. The use of a coal slime heavy medium cyclone separator for full-size separation, combined with subsequent water replenishment, dilution, magnetic separation, concentration, classification, and dewatering, ensures both independent or mixed recovery of coarse and fine products and achieves efficient recycling of the medium.

[0013] Meanwhile, the overflow, underflow, and filtrate generated during the sorting process are returned to the thickener. When the load of the coking coal thickener exceeds 85%, the filtrate from the filter press is switched to the circulating water tank, forming a closed-loop water circulation system. This significantly reduces water and media consumption, reduces gangue sludge formation, and achieves clean, efficient, and low-energy coarse coal slime sorting.

[0014] According to another aspect, at least one embodiment of the present invention also provides a coal slime heavy medium hydrocyclone for use in a full-size heavy medium separation process for coarse coal slime of power coal, comprising: The sorting body has a cylindrical section and a conical section connected to the lower end of the cylindrical section; An arc-shaped feed pipe is provided on the side wall of the cylindrical section, and the inner wall of the arc-shaped feed pipe has an arc-shaped transition. The light product discharge pipe is coaxially disposed at the center of the bottom plate of the cylindrical section; The heavy product discharge pipe is connected to the small end of the conical section and is coaxially arranged with the light product discharge pipe; The sorting body is arranged at a negative angle where the light product discharge pipe is higher than the heavy product discharge pipe.

[0015] According to one embodiment of this application, the angle between the mounting axis of the sorting body and the horizontal plane is an acute angle.

[0016] According to one embodiment of this application, the outer wall of the light product discharge pipe located at one end of the sorting body is provided with a spiral guide groove.

[0017] This invention provides a coal slime heavy medium hydrocyclone. Compared with existing technologies, the coal slime heavy medium hydrocyclone adopts a negative angle arrangement where the light product discharge pipe is higher than the heavy product discharge pipe, combined with the arc-shaped transition structure on the inner wall of the arc-shaped feed pipe, which significantly optimizes the internal flow field distribution. The negative angle arrangement can extend the separation path of fine particles in the hydrocyclone. Specifically, when the light product discharge pipe is higher than the heavy product discharge pipe, the axial velocity component decreases, and the residence time of the material in the conical section is extended, which is beneficial to the separation of fine particles, effectively reduces the mixing of heavy products into light products, and improves the separation accuracy and lower separation limit (up to 0.074 mm).

[0018] Compared with tangential straight pipes, arc-shaped feed pipes can reduce local eddy current losses and reduce inlet pressure loss by about 15% to 20%, allowing the suspension to enter the cylindrical section at a more stable tangential velocity. This adapts to low-pressure feed conditions of no more than 0.15 MPa, thereby reducing pumping energy consumption and equipment wear.

[0019] The coaxially arranged light and heavy product discharge pipes ensure the symmetry of the axial flow field, avoiding interference from flow deviation on the separation effect. Overall, this hydrocyclone has a simple structure, large processing capacity, and high separation efficiency. It is especially suitable for the full-size heavy medium separation of coarse coal slime in power coal, and can effectively suppress gangue sliming and reduce media consumption. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 A process flow diagram of a full-size heavy medium separation process for coarse coal slime in power plants provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of a coal slime heavy medium cyclone according to another embodiment of the present invention; Figure 3 For the present invention Figure 2 A schematic diagram of the structure of a coal slime heavy medium cyclone from another perspective.

[0022] In the diagram: 1. Sorting body, 2. Cylindrical section, 3. Conical section, 4. Arc-shaped feed pipe, 5. Light product discharge pipe, 6. Heavy product discharge pipe. Detailed Implementation To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar components or components having the same or similar functions throughout. The described embodiments are some, but not all, embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0023] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, an indirect connection through an intermediate medium, or the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0024] In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] The terms "first," "second," "third," "fourth," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of this application described herein can be implemented, for example, in a sequence other than those illustrated or described herein.

[0026] To make the drawings concise and easy to understand, some drawings only show one of the components with the same structure or function, or only one of them is marked. In this article, "one" not only means "only one", but can also mean "more than one", and "several" includes "two" and "more than two".

[0027] Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. It is understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. The embodiments of this application are described in detail below with reference to the accompanying drawings.

[0028] This embodiment relates to the field of coal sorting technology. The full-size heavy medium separation process and heavy medium hydrocyclone for coarse coal slime provided in this embodiment are applied to the sorting and recovery stage of coarse coal slime in a power coal preparation plant. This embodiment solves the problems of gangue sludge formation, high-ash fine mud contamination of clean coal products, poor adaptability of the sorting system to coal quality fluctuations, and high media consumption and system energy consumption in existing wet sorting processes. All technical solutions in this embodiment strictly adhere to the scope of protection of the claims, and simultaneously match the equipment layout and material flow direction in the sorting process flow diagram.

[0029] See attached document Figure 1 (Sorting Process Flow Diagram) The sorting process provided in this embodiment relies on a complete sorting system. The sorting system includes a mixing tank, a pumping system, a coal slime heavy medium hydrocyclone, a clean coal magnetic separator, a tailings magnetic separator, a dewatering screen, a centrifuge, a clean coal thickener, a tailings thickener, a filter press, and a circulating water tank. The core equipment of the pumping system is the mixing pump. The complete process of this sorting process includes four core stages: coarse coal slime raw material pretreatment, heavy medium separation, product classification and dewatering, and water circulation and media recovery. This sorting process is equipped with intelligent detection and control throughout the entire process.

[0030] Before this sorting process is implemented, operators use an online particle size analyzer and an online ash analyzer to perform online particle size analysis and ash content testing on the feed coarse coal slime. Based on the test results, the control system automatically sets the target sorting density and initial feed pressure. Operators prepare the coarse coal slime into a uniformly mixed coal slurry with a concentration of not less than 25%. The coal slurry, production water, and qualified media are then fed into a mixing tank. A double-impeller agitator is installed inside the mixing tank. The double-impeller agitator continuously stirs the materials in the tank, ensuring thorough mixing of the coal slurry and qualified media to obtain a stable feed suspension. The density of the feed suspension is controlled within the range of 1.40–1.80 g / cm³. The density of the feed suspension can be adjusted according to the raw coal quality and product quality requirements.

[0031] The mixing pump delivers the feed suspension from the mixing tank into the coal slime heavy medium hydrocyclone. The feed suspension undergoes efficient separation of light and heavy products within the centrifugal force field of the coal slime heavy medium hydrocyclone. The coal slime heavy medium hydrocyclone outputs clean coal product streams and tailings product streams, respectively. The feed pressure of the coal slime heavy medium hydrocyclone is no greater than 0.15 MPa.

[0032] This separation process performs independent water replenishment, dilution, magnetic separation, concentration, classification, and dewatering treatments on the clean coal product stream and the tailings product stream. The processing flow for the clean coal product stream is as follows: Operators replenish and dilute the clean coal product stream with water to reduce the viscosity of the suspension. The diluted clean coal product stream is then fed into a clean coal magnetic separator. The clean coal magnetic separator separates the material into magnetic concentrate and magnetic tailings. The magnetic concentrate produced by the clean coal magnetic separator is returned to the mixing tank through pipelines, achieving media recycling. The magnetic tailings produced by the clean coal magnetic separator are fed into a dewatering screen. The dewatering screen classifies and dewaters the material, obtaining oversize and undersize water. The oversize from the dewatering screen is then sent to a centrifuge.

[0033] The centrifuge performs secondary centrifugation and dewatering on the material, ultimately outputting refined coal product one. The centrifugal liquid generated during the centrifuge dewatering process is sent to a refined coal thickener. The underflow from the dewatering screen is also sent to the refined coal thickener. The refined coal thickener concentrates and classifies the material, obtaining underflow and overflow respectively. The underflow from the refined coal thickener is sent to a filter press. The filter press dewaters the material, ultimately outputting refined coal product two. The overflow from the refined coal thickener is sent to a circulating water tank. Refined coal product one and refined coal product two after dewatering can be recovered independently or mixed and homogenized to form the final refined coal product.

[0034] The processing flow for the tailings product stream is as follows: Operators dilute the tailings product stream with water to reduce the viscosity of the suspension. The diluted tailings product stream is then fed into a tailings magnetic separator. The magnetic separator separates the magnetic components of the material, yielding magnetic concentrate and magnetic tailings. The magnetic concentrate produced by the tailings magnetic separator is returned to the mixing tank via pipeline, achieving media recycling. The magnetic tailings produced by the tailings magnetic separator are fed into a dewatering screen. The dewatering screen classifies and dewaters the material, yielding oversize and undersize water. The oversize from the dewatering screen is directly used as tailings product one. The undersize water from the dewatering screen is fed into a tailings thickener. The tailings thickener concentrates and classifies the material, yielding underflow and overflow. The underflow from the tailings thickener is fed into a filter press. The filter press dewaters the material, ultimately outputting tailings product two. The overflow from the tailings thickener is sent to a circulating water tank. The dehydrated tailings product 1 and tailings product 2 can be recycled independently, or they can be mixed and homogenized to become the final tailings product.

[0035] Under normal circumstances, the overflow from the coal thickener, tailings thickener, and filter press filtrate generated during the sorting process are all sent to the circulating water tank to achieve water resource recycling. The control system monitors the operating load of the coal thickener in real time. When the operating load of the coal thickener continuously exceeds 85%, the control system automatically switches the filter press filtrate on the coal side to the circulating water tank, while the remaining portion returns to the thickener, realizing a closed-loop water circulation system. This prevents the coal thickener from overloading and producing coarser filtrate, while also reducing production water consumption.

[0036] This sorting process is equipped with a fully intelligent closed-loop control system. The control system uses a PLC as its core. Operators install a densitometer at the outlet pipe of the mixing pump. Operators install a pressure sensor at the inlet of the coal slime heavy medium cyclone separator. Operators install online ash analyzers at the outlet positions of the clean coal product stream and the tailings product stream. The densitometer, pressure sensor, and online ash analyzer are connected to the control system. The densitometer, pressure sensor, and online ash analyzer collect real-time information on suspension density, feed pressure, and product ash content during the sorting process. Combined with information on magnetic material content and coal slime content obtained from other sensors, the detection data is transmitted to the control system in real time.

[0037] Based on the collected detection data, the control system automatically adjusts the opening degree of the medium addition valve and water supply valve, as well as the medium diversion ratio. The control system can stabilize the separation density control accuracy within ±0.002 g / cm³. When the online ash analyzer detects a deviation of ±0.5% in the clean coal ash content relative to the target value, the control system prioritizes adjusting the water supply in the mixing tank. The control system corrects the clean coal ash content by adjusting the water supply to change the separation density of the feed suspension. If the clean coal ash content still does not reach the target range after adjusting the separation density, the control system automatically adjusts the feed pressure of the coal slime heavy medium cyclone. The control system adjusts the lower separation limit and separation accuracy by changing the centrifugal force field within the cyclone. When the absolute change in the -0.074 mm fine mud content in the feed exceeds ±5 percentage points, the control system simultaneously adjusts the separation density and feed pressure. Through dual-parameter coordinated adjustment, the control system offsets the impact of fine mud content changes on the separation effect, ensuring stable clean coal product quality.

[0038] The coal slime heavy medium cyclone provided in this embodiment is the core separation equipment in the above-mentioned separation process. For example... Figure 2 The diagram shows a schematic of a coal slime heavy medium cyclone separator. The separator includes a main separator 1. The main separator 1 has a cylindrical section 2 and a conical section 3. The larger end of the conical section 3 is connected to the lower end of the cylindrical section 2. An arc-shaped feed pipe 4 is installed on the side wall of the cylindrical section 2. The inner wall of the arc-shaped feed pipe 4 has an arc-shaped transition. The outlet of the arc-shaped feed pipe 4 is tangentially connected to the inner wall of the cylindrical section 2. A light product discharge pipe 5 is coaxially installed at the center of the bottom plate of the cylindrical section 2. The smaller end of the conical section 3 is connected to a heavy product discharge pipe 6. The heavy product discharge pipe 6 and the light product discharge pipe 5 are coaxially arranged. The main separator 1 is arranged with the light product discharge pipe 5 at a negative angle higher than the heavy product discharge pipe 6. The angle between the installation axis of the main separator 1 and the horizontal plane is an acute angle.

[0039] A spiral guide groove is provided on the outer wall of the light product discharge pipe 5 at one end of the sorting body 1. The spiral guide groove has a continuous spiral structure. The spiral direction of the spiral guide groove is consistent with the main swirling direction formed by the feed suspension in the sorting body 1. Let the inner diameter of the cylindrical section 2 be D, then the pitch P of the spiral guide groove satisfies 0.3D≤P≤0.8D. The groove depth h of the spiral guide groove satisfies 0.02D≤h≤0.08D. The groove width w of the spiral guide groove satisfies 0.05D≤w≤0.15D. The spiral helix angle β of the spiral guide groove satisfies 15°≤β≤45°. Where D is the inner diameter of the cylindrical section 2.

[0040] When the coal slime heavy medium hydrocyclone is working, the feed suspension enters the cylindrical section 2 tangentially along the arc-shaped feed pipe 4. Within the sorting body 1, the feed suspension forms an outer swirling flow and an inner swirling flow. The outer swirling flow spirals downwards along the inner walls of the cylindrical section 2 and the conical section 3 towards the heavy product discharge pipe 6. Under centrifugal force, the outer swirling flow separates light and heavy particles, with the heavy particles entering the heavy product discharge pipe 6 along with the outer swirling flow.

[0041] The internal swirling flow spirals upwards along the axis of the sorting body 1 towards the light product discharge pipe 5. This internal swirling flow carries the sorted light particles towards the light product discharge pipe 5, ultimately discharging them through it. At the junction of the outer wall of the light product discharge pipe 5 and the bottom plate of the cylindrical section 2, some of the suspension does not enter the main sorting flow field but flows directly down the outer wall of the light product discharge pipe 5, directly entering its inlet and forming a short-circuit flow. This short-circuit flow carries unsorted heavy particles into the light product discharge pipe 5, leading to an increase in the ash content of the clean coal product and significantly reducing the equipment's sorting accuracy.

[0042] The spiral guide groove is used to eliminate short-circuit flow. Short-circuit flow flowing downwards along the outer wall of the light product discharge pipe 5 enters the spiral guide groove and is forced to change direction due to the constraint of the groove's spiral wall. The short-circuit flow, following the trajectory of the spiral guide groove, forms a rotating flow consistent with the rotation direction and axial movement direction of the main swirling flow field. The short-circuit flow, which originally moved directly towards the inlet of the light product discharge pipe 5, is guided by the spiral guide groove to the main swirling flow field of the sorting body 1, re-enters the outer swirling flow, and participates in the sorting process of light and heavy particles.

[0043] The spiral guide groove, through the above-mentioned structural constraints, directly reduces the proportion of short-circuit flow, reduces the probability of unsorted heavy particles entering the clean coal product, regulates the flow field distribution around the light product discharge pipe 5, reduces flow field turbulence, improves the stability of the main swirling flow field, reduces the flow resistance during the discharge process of light products, adapts to low-pressure feeding conditions of ≤0.15MPa, and reduces equipment operating energy consumption and wear.

[0044] In this embodiment, the length L1 of the cylindrical section 2 and the diameter D of the cylindrical section 2 satisfy 1.5D≤L1≤2.5D. This dimensional ratio ensures that the hydrocyclone maintains a stable axial flow field under the condition of feed pressure ≤0.15MPa, avoiding the decrease in sorting accuracy caused by flow field turbulence during low-pressure feed. The diameter d1 of the light product discharge pipe 5 satisfies 0.4D≤d1≤0.55D. The inlet radius of curvature R of the arc-shaped feed pipe 4 satisfies 0.1D≤R≤1.0D. The cross-section of the arc-shaped feed pipe 4 is rectangular. The long side a and the short side b of the rectangle satisfy 1b≤a≤3b, and 0.18L1≤a≤0.36L1. The cone angle α of the conical section 3 satisfies 20°≤α≤60°. The diameter d2 of the heavy product discharge pipe 6 satisfies 0.75d1≤d2≤0.95d1. The length L2 of the heavy product discharge pipe 6 satisfies 0.3d2≤L2≤0.6d2. The angle θ between the installation axis of the sorting body 1 and the horizontal plane satisfies 0°<θ≤90°.

[0045] In some embodiments, the angle between the mounting axis of the sorting body 1 and the horizontal plane is set to 5°. This angle is suitable for working conditions where the feed has a high fine mud content and the lower limit requirement for sorting is low. This angle can prolong the residence time of the material in the sorting body 1 and enhance the sorting effect of fine-grained materials.

[0046] In other embodiments, the angle between the mounting axis of the sorting body 1 and the horizontal plane is set to 15°. This angle is suitable for working conditions with coarse feed particle size and large processing capacity requirements. This angle can improve material discharge efficiency and ensure the single-machine processing capacity of the equipment. In a preferred embodiment, the angle between the mounting axis of the sorting body 1 and the horizontal plane is set to 10°. This angle can balance sorting accuracy and equipment processing capacity, and is suitable for the sorting needs of most coarse coal slime from thermal coal.

[0047] In some alternative implementations, a pre-desliming device is added to the pretreatment stage of the coarse coal slime raw material. The pre-desliming device pre-deslims the feed coarse coal slime. The pre-desliming device removes some of the high-ash fine mud in advance. The screen openings of the pre-desliming device can be adjusted according to the particle size distribution of the feed.

[0048] In some alternative implementations, the combination of the dewatering screen and centrifuge can be adjusted according to the product moisture requirements. For scenarios with lenient moisture requirements, only the dewatering screen is used to dewater the coarse coal product. For scenarios with strict moisture requirements, a secondary drying device is added after the centrifuge. The secondary drying device further reduces the product moisture content.

[0049] In some optional implementations, a raw coal quality prediction model is added to the intelligent control process. This model predicts coal quality fluctuation trends based on historical and real-time monitoring data of the raw coal being fed into the system. The raw coal quality prediction model pre-adjusts the sorting parameters. This model enables feedforward control of the sorting process.

[0050] In some alternative implementations, an arc screen is added before the clean coal magnetic separator and the tailings magnetic separator in the media recovery stage. The arc screen removes most of the qualified media in advance. The arc screen reduces the processing load on the magnetic separator. The arc screen improves media recovery efficiency. The arc screen reduces media consumption.

[0051] In some alternative implementations, the arc-shaped feed pipe 4 is configured as a multi-section detachable structure. The curvature of different sections is adjustable. Operators can replace the feed pipe section with the corresponding curvature according to the required feed concentration and throughput. This structure facilitates the individual replacement of vulnerable sections. This structure reduces equipment maintenance costs.

[0052] In some alternative implementations, the cylindrical section 2 and the conical section 3 of the sorting body 1 are connected by a flange-mounted, detachable structure. Operators can replace the conical section 3 with different cone ratios according to the feed particle size distribution and sorting requirements. This structure allows for adjustment of the equipment's sorting characteristics and improves the equipment's adaptability to various operating conditions.

[0053] In some alternative embodiments, the light product discharge pipe 5 is configured with an axially adjustable structure. The operator can adjust the depth to which the light product discharge pipe 5 extends into the sorting body 1. This structure allows for adjustment of the equipment's sorting density and sorting effect. Parameter adjustments can be made without stopping and disassembling the equipment.

[0054] Regarding material selection, the inner walls of the sorting body 1, the arc-shaped feed pipe 4, the light product discharge pipe 5, and the heavy product discharge pipe 6 can be lined with wear-resistant ceramic layers or polyurethane wear-resistant materials. Operators can select the appropriate wear-resistant material based on the abrasiveness of the feed material. This material selection can extend the service life of the equipment.

[0055] The cylindrical section 2 of the coal slime heavy medium cyclone used in this embodiment has a diameter D of Ф300mm. The length of the cylindrical section 2 is L1=2D. The diameter of the light product discharge pipe 5 is d1=0.5D. The inlet radius of curvature of the arc-shaped feed pipe 4 is R=0.6D. The long side of the rectangular cross-section of the feed inlet is a=2.7b, and a=0.19L1. The cone angle of the conical section 3 is α=30°. The diameter of the heavy product discharge pipe 6 is d2=0.9d1. The length of the heavy product discharge pipe 6 is L2=0.4d2. The angle between the mounting axis of the sorting body 1 and the horizontal plane is θ=30°. The spiral guide groove on the outer wall of the light product discharge pipe 5 has a pitch P=0.5D, a groove depth h=0.05D, a groove width w=0.1D, and a spiral helix angle β=30°.

[0056] This embodiment's separation process treats 3-0mm coarse coal slime from power coal. The operator prepares the coarse coal slime into a uniformly mixed slurry with a 40% concentration. The slurry is mixed with a qualified medium in a mixing tank to form a feed suspension with a density of 1.45 g / cm³. A mixing pump delivers the feed suspension to a coal slime heavy medium hydrocyclone at a feed pressure of 0.12 MPa for separation. The clean coal product stream and tailings product stream are diluted with water to a concentration of 20% before being sent to the corresponding clean coal magnetic separator and tailings magnetic separator. The intelligent control system sets the target value for clean coal ash content to 11%. When the clean coal ash content reaches 11.5%, the system first increases the water supply pipe opening by 8%; if the ash content is still higher than 11.3% after 30 seconds, the hydrocyclone feed pressure is increased by 5%; if the ash content is lower than 10.5%, the system performs reverse adjustment.

[0057] This embodiment ultimately achieves a sorting accuracy Ep of 0.09 g / cm³ (the industry standard range is 0.08–0.12 g / cm³), an overall quantity efficiency of 96%, a medium consumption of 1.2 kg per ton of coal, and a sorting lower limit of 0.074 mm, thus fully realizing efficient sorting of all particle sizes of coarse coal slime in thermal coal.

[0058] The pumping system mentioned in this embodiment uses a variable frequency centrifugal pump. The variable frequency centrifugal pump, in conjunction with the control system, achieves stepless adjustment of the feed pressure. Both the clean coal magnetic separator and the tailings magnetic separator are wet permanent magnet separators. The wet permanent magnet separator ensures efficient media recovery. Both the clean coal thickener and the tailings thickener are high-efficiency inclined tube thickeners. The high-efficiency inclined tube thickener improves the thickening and grading efficiency. The dewatering screen uses a high-frequency vibrating dewatering screen. The centrifuge uses a sedimentation filtration centrifuge. The filter press uses a chamber filter press.

[0059] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A whole-size heavy medium separation process for coarse coal slime in thermal coal, characterized in that, Includes the following steps: S1: Perform online particle size analysis and ash content testing on the coarse coal slime, and set the target value of the sorting density and the initial value of the feed pressure based on the test results; prepare the coarse coal slime into a coal slurry, mix it with qualified medium in a mixing tank, and obtain the feed suspension; S2: The feed suspension is fed into a coal slime heavy medium cyclone separator for separation to obtain clean coal product stream and tailings product stream; S3: The clean coal product stream and the tailings product stream are respectively subjected to water dilution, magnetic separation, concentration and classification and dewatering treatment to obtain coarse product and fine product respectively; S4: The overflow, underflow, and filtrate generated during the sorting process are returned to the thickener for treatment. When the operating load of the coal thickener is continuously higher than 85%, the filtrate from the coal filter press is switched to the circulating water tank to realize the closed-loop water circulation of the system.

2. The whole-size heavy medium separation process for coarse coal slime of thermal coal according to claim 1, characterized in that, The concentration of the coal slurry in S1 is not less than 25%, and the density of the feed suspension is 1.40 to 1.80 g / cm3.

3. The whole-size heavy medium separation process for coarse coal slime of thermal coal according to claim 1, characterized in that, The coarse product in S3 is dewatered by a high-frequency screen and then by centrifugation, while the fine product is dewatered by a pressure filter. The coarse product and the fine product are either independently recovered or mixed to form the final clean coal product.

4. The whole-size heavy medium separation process for coarse coal slime of thermal coal according to claim 1, characterized in that, It also includes intelligent control steps: based on the detection data of the density meter and pressure sensor, and combined with the information on the content of magnetic materials and coal slime obtained by other sensors, the medium addition valve, water supply valve and medium diversion ratio are adjusted to stabilize the sorting density control accuracy within ±0.002 g / cm³. The density meter is installed in the outlet pipe of the mixing pump, and the pressure sensor is installed in the inlet of the hydrocyclone.

5. The whole-size heavy medium separation process for coarse coal slime of thermal coal according to claim 4, characterized in that, The intelligent control steps also include: when the online ash analyzer detects that the deviation of the clean coal ash content from the target value reaches ±0.5%, adjusting the water replenishment amount in the mixing tank to change the separation density; If the ash content of the clean coal still does not meet the standard after adjusting the separation density, then adjust the feed pressure of the coal slime heavy medium cyclone. When the fine mud content in the feed exceeds the preset range, adjust the sorting density and feed pressure.

6. The whole-size heavy medium separation process for coarse coal slime of thermal coal according to claim 5, characterized in that, The preset range for the change in fine mud content is specifically defined as an absolute change in the content of -0.074mm particle size exceeding ±5 percentage points.

7. The whole-size heavy medium separation process for coarse coal slime of thermal coal according to claim 1, characterized in that, The feed pressure of the coal slime heavy medium cyclone described in S2 is no greater than 0.15 MPa.

8. A coal slime heavy medium cyclone, applied in the full-size heavy medium separation process of coarse coal slime for power plants as described in any one of claims 1 to 7, characterized in that, include: The sorting body (1) has a cylindrical section (2) and a conical section (3) connected to the lower end of the cylindrical section (2). An arc-shaped feed pipe (4) is provided on the side wall of the cylindrical section (2), and the inner wall of the arc-shaped feed pipe (4) has an arc transition. The light product discharge pipe (5) is coaxially arranged at the center of the bottom plate of the cylindrical section (2); The heavy product discharge pipe (6) is connected to the small end of the conical section (3) and is coaxially arranged with the light product discharge pipe (5); The sorting body (1) is arranged at a negative angle with the light product discharge pipe (5) higher than the heavy product discharge pipe (6).

9. A coal slime heavy medium cyclone according to claim 8, characterized in that, The angle between the installation axis of the sorting body (1) and the horizontal plane is an acute angle.

10. A coal slime heavy medium cyclone according to claim 8, characterized in that, The light product discharge pipe (5) is provided with a spiral guide groove on the outer wall of one end of the sorting body (1).

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