A heavy medium separation process for fine coal without desliming based on dilute medium classification

Abstract

The present invention discloses a non-slime raw coal heavy medium separation process based on dilute medium classification separation, which mainly includes the following steps: Step a, raw coal separation; Step b1, clean coal desliming; Step b2, middlings desliming; Step b3, gangue desliming; Step c, dilute medium classification separation; Step d1, coarse clean coal desliming; Step d2, coarse middlings desliming; Step e1, overflow magnetic separation; Step e2, clean coal magnetic separation; Step e3, middlings magnetic separation; Step e4, gangue magnetic separation; Step f, combined medium blending; Step g, dilute medium blending. This process completes classification separation of the fixed combined medium diversion of clean coal and the dilute medium under the screen in a three-product coal slime heavy medium cyclone group, integrating medium classification recovery, efficient separation of coarse coal slime, stabilizing and reducing the magnetic separation load, with a simple process, less investment, low medium consumption, low operating cost, and remarkable economic benefits.

Description

Technical Field

[0001] The invention belongs to the technical field of coal preparation, and in particular relates to a heavy medium separation process for non-de-slimed fine coal based on dilute medium classification separation. Background Art

[0002] The heavy medium separation process of fine coal without desliming is not only simple in process, high in precision and automation, but also has a wide separation particle size, and can simultaneously achieve efficient separation of raw coal with an upper limit of 50 (80) mm and a lower limit of 0.25 mm. Therefore, it is widely used in the washing and separation of coking coal in my country's coal preparation plants. This process uses the original coal slime in the raw coal and the circulating medium as the low-density medium composition, and the fine coal (50-1 mm) and coarse coal slime (1-0.25 mm) are separated synchronously in a set of medium systems. After the fine coal is de-mediumed and dehydrated, fine clean coal, fine medium coal and fine gangue are obtained. The coarse coal slime is discharged from the tailings after magnetic separation in the dilute medium system, and after dehydration, coarse clean coal slime, coarse medium coal slime and tailing coal slime products are obtained.

[0003] Due to the inherent characteristics of the existing non-de-sliming fine coal heavy medium process, fine coal, coarse coal slime, and fine coal slime (<0.25mm) all enter a set of medium sorting system, which results in the following disadvantages: ① The finer the material particle size, the higher the sorting density and the lower the precision of the fine coal heavy medium cyclone, and it is difficult to achieve the best sorting effect for each particle size in a set of medium system. The ash content of coarse clean coal slime is often 1% to 2% higher than that of fine clean coal, which has an adverse effect on the total clean coal yield and ash content; ② All coal slime Entering the medium system, the medium system can only increase the combined medium diversion to maintain the system's coal slime balance, resulting in a large load on the clean coal magnetic separation operation with combined medium diversion and dilute medium as feed, and high medium loss with tailings; ③ As a key variable for controlling density, barrel position, and medium stability, the combined medium diversion is in a dynamic adjustment state for a long time, resulting in unstable fluctuations in the feed of clean coal magnetic separation, and it is difficult to ensure the magnetic separation efficiency; ④ The magnetic separation process often ignores the particle size factor of magnetite powder, the medium wears out over a long period of time, and the problem of magnetite powder <20μm being easily lost in the tailings due to its weak magnetism has not been taken seriously. Summary of the invention

[0004] The purpose of the present invention is to provide a heavy medium separation process for non-demudified fine coal based on dilute medium classification separation, so as to solve the problems of poor coarse coal slime separation, magnetic separation feed fluctuation, large medium system load and high medium consumption in the existing heavy medium separation process for non-demudified fine coal.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: a heavy medium separation process of unslimed fine coal based on dilute medium classification separation, which is specifically implemented according to the following steps:

[0006] Step a, fine raw coal sorting: the fine raw coal with a particle size of no more than 50 mm is sorted in a three-product fine coal heavy medium cyclone under the action of a qualified medium to obtain fine clean coal, fine medium coal and fine gangue;

[0007] Step b 1 , fine clean coal de-mediation: in step a, the fine clean coal is de-mediated by a curved screen and a de-mediation screen to obtain curved screen combined media, de-mediation screen combined media, de-mediation screened thin media and screened oversize; wherein the curved screened combined media is divided into two parts by a diverter, a part of the curved screened combined media and the de-mediation screened combined media are sent to the combined media barrel together, and the remaining curved screened combined media are diverted and sent to the thin media barrel together with the de-mediation screened thin media, and the screened oversize is used as a clean coal product after dehydration;

[0008] Step b 2 , de-mediumizing the fine and medium coal: in step a, the fine and medium coal is de-mediumized by a curved screen and a de-mediumizing screen to obtain a curved screen combined medium, a de-mediumizing screen combined medium, a de-mediumizing screen thin medium and a screen oversize; wherein the curved screen combined medium and the de-mediumizing screen combined medium are de-mediumized; the de-mediumizing screen thin medium is de-mediumized by magnetic separation, and the screen oversize is dehydrated as a medium coal product;

[0009] Step b 3 , the final gangue is removed: in step a, the final gangue is removed by an arc screen and a removal screen to obtain an arc screen combined medium, a removal screen combined medium, a removal screen dilute medium and a screen oversize; wherein the arc screen combined medium and the removal screen combined medium are removed from the combined medium barrel; the removal screen dilute medium is removed from the gangue by magnetic separation, and the screen oversize is used as the gangue product;

[0010] Step c, rare earth classification and sorting: b 1 The arc-shaped screen combined medium splitting and the de-screened thin medium in the step are pumped to the two-stage three-product coal slime heavy medium cyclone group for graded sorting after being buffered by the thin medium barrel to obtain overflow products, coarse clean coal (mid-stream) and coarse medium coal (bottom stream);

[0011] Step d 1 , coarse clean coal de-mediation: in step c, the coarse clean coal is fed into a curved screen for de-mediation to obtain an oversize and undersize mixed medium; the oversize is subjected to a clean coal magnetic separation operation, and the undersize mixed medium is diverted, and the ratio of the de-mixing barrel or the clean coal magnetic separator is adjusted according to the coal quality, separation density, and suspension characteristics;

[0012] Step d 2 , Coarse and medium coal de-mediation: In step c, the coarse and medium coal is fed into a curved screen for de-mediation to obtain oversize and undersize mixed media, the oversize is sent to the medium coal magnetic separation operation, and the undersize mixed media is sent to the mixed media barrel;

[0013] Step e 1 , Magnetic separation of overflow products: The overflow products in step c are fed into the overflow magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tail; the magnetic concentrate is split, and the ratio of the decomposition medium barrel and the dilution medium barrel is adjusted according to the density of the dilution medium barrel, and the magnetic tail is used as coal slime water for subsequent concentration operations;

[0014] Step e2 , Clean coal magnetic separation: step d 1 The material on the middle screen and part of the mixed medium under the screen are fed into the clean coal magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tail; the magnetic concentrate is the same as step e. 1 After the medium magnetic fines are combined, a split flow is set up, and the ratio of the decomposition medium barrel and the dilute medium barrel is adjusted according to the density of the dilute medium barrel; the magnetic tail is used as a coarse clean coal slime product after classification and dehydration; when the feed concentration of the clean coal magnetic separator is too high, water spraying can be increased;

[0015] Step e 3 , Coal Magnetic Separation: Step b 2 Medium removal screening and thinning, step d 2 The material on the middle arc screen is fed into the medium coal magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tailings; the magnetic concentrate goes to the mixing barrel, and the magnetic tailings are graded and dehydrated as coarse medium coal slime products;

[0016] Step e 4 , Gangue magnetic separation: step b 3 The medium-removed medium is fed into the gangue magnetic separator, and magnetic separation is performed to obtain magnetic concentrate and magnetic tailings; the magnetic concentrate goes to the combined medium barrel, and the magnetic tailings are used as tail coal products after dehydration;

[0017] Step f, mixing barrel: Step b 1 Middle arc screen (de-screening) and de-screening, step b 2 、b 3 Middle arc screen and stripping screen, step d 1 Medium sieve under the medium (removal of medium), step d 2 Middle sieve and medium, step e 1 、e 2 Medium magnetic concentrate (removal of medium), step e 3 、e 4 The supplementary magnetite powder and water are fed into the combined medium barrel, and the circulating medium is returned to step a by pumping after buffering;

[0018] Step g, dilution barrel preparation: b 1 In step e, the arc screen combines the media flow and the media removal screen to dilute the media. 1 、e 2 The medium magnetic concentrate (removing the diluent) is fed into the diluent barrel and returned to step c after buffering.

[0019] As a preferred technical solution of the present invention, the b 1 In the step, the combined flow rate of the thinning medium barrel is a fixed value, which is determined according to the final coal sorting density and the coal slime content, and is set between 25% and 35%.

[0020] As a preferred technical solution of the present invention, in the step c, the feed pressure of the three-product coal slime heavy medium cyclone group is between 0.1 and 0.15 MPa.

[0021] As a preferred technical solution of the present invention, in the step c, the three-product coal slime heavy medium cyclone unit is composed of two sections of two-product small-diameter cyclones arranged in series and in parallel, one section is cylindrical and the second section is conical, the cone angle of the two sections is between 15° and 20°, and the installation angle is between 10° and 15°.

[0022] As a preferred technical solution of the present invention, the e 2 In the step, the water spraying amount is determined according to the feed concentration of the clean coal magnetic separator, and the mass concentration is between 15% and 25%.

[0023] As a preferred technical solution of the present invention, the e 1 In the step, the magnetic field strength of the overflow magnetic separator is 2200-2500 GS, e 2 、e 3 、e 4 The magnetic field strength of the magnetic separator in the step is 1500-1800 GS.

[0024] As a preferred technical solution of the present invention, in the step f, the density of the combined medium barrel is controlled to be the target of the first stage sorting of the three-product fine coal heavy medium cyclone, and is determined according to the ash content and coal quality of the fine clean coal, generally between 1.35 and 1.45 kg / L;

[0025] As a preferred technical solution of the present invention, in the step g, the density of the dilute medium barrel is adjusted to target the second-stage separation of the three-product coal slime heavy medium cyclone, and is determined according to the ash content and coal quality of the coarse and fine coal slime, generally between 1.10 and 1.20 kg / L.

[0026] The beneficial effects of the present invention are as follows: (1) The present invention is a non-de-slimed fine coal heavy medium separation process based on dilute medium classification and separation, and the fixed clean coal combined medium, clean coal dilute medium, and magnetic fine medium are precisely controlled and fed into the three-product coal slime heavy medium cyclone group. The coal slime and heavy medium are classified and separated according to the particle size and density differences in the centrifugal field, ensuring the controllability, adjustability and high precision of the coarse coal slime separation. (2) The present invention is a non-de-slimed fine coal heavy medium separation process based on dilute medium classification and separation, and the dilute medium is recycled and disposed of separately after classification and concentration, and the classification overflow with low magnetic content is directly magnetically separated; the coarse clean coal combined medium with medium magnetic content is set to split, and the magnetic separation or combined medium barrel is removed; the coarse medium coal combined medium with high magnetic content is removed to the combined medium barrel. The coal slime in the medium system is discharged in a classification + split mode, and the split flow of the clean coal magnetic separation is small and the fluctuation is small, which stabilizes and reduces the magnetic separation load, and helps to improve the clean coal magnetic separation efficiency. (3) The present invention is a heavy medium separation process for fine coal without desliming based on dilute medium classification and sorting. The overflow of the dilute medium classification is recovered separately by an overflow magnetic separator, and the high magnetic field is used to strengthen the recovery of ultra-fine magnetite, thereby reducing the loss of ultra-fine magnetite with low magnetic properties. (4) The present invention is a heavy medium separation process for fine coal without desliming based on dilute medium classification and sorting. The process flow is simple, easy to operate, requires little investment, has low operating costs, and has significant economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 It is a principle diagram of a heavy medium separation process of non-de-slimed fine coal based on dilute medium classification separation of the present invention;

[0029] Figure 2 This is an equipment connection diagram of a heavy medium separation process for non-de-slimed fine coal based on dilute medium classification separation of the present invention;

[0030] In the figure: A. Three-product fine coal heavy medium cyclone; B 1 . Fine coal curved screen; B 2 .B-shaped screen for fine and medium coal; 3 .Curved screen for final gangue; 1 . Fine coal de-mediation screen; C 2 . Fine and medium coal removal screen; C 3 .Finally gangue removal screen; D.Finally coal and medium splitter; E. 1 .Thin medium barrel; E 2 .Combination barrel; E 3 . Coarse and fine coal slime barrel; E 4 . Coarse and medium coal slime bucket; E 5 . Tail coal slime bucket; F 1 .Dilute intervention material pump; F2 .Combined feed pump; G.Three-product coal slime heavy medium cyclone group; H 1 . Coarse and clean coal curved screen; H 2 . Coarse and medium coal arc screen; I. Coal slime and medium flow divider; J. Magnetic fine flow divider; K 1 .Coal slime magnetic separator; K 2 . Clean coal magnetic separator; K 3 .China Coal Magnetic Separator; K 4 .Gangera magnetic separator. DETAILED DESCRIPTION

[0031] like Figure 1 As shown, a heavy medium separation process for non-de-slimed fine coal based on dilute medium classification separation of the present invention is specifically implemented according to the following steps:

[0032] Step a, fine raw coal sorting: the fine raw coal with a particle size of no more than 50 mm is sorted in a three-product fine coal heavy medium cyclone under the action of a qualified medium to obtain fine clean coal, fine medium coal and fine gangue;

[0033] Step b 1 , fine clean coal de-mediation: in step a, the fine clean coal is de-mediated by a curved screen and a de-mediation screen to obtain curved screen combined media, de-mediation screen combined media, de-mediation screened thin media and screened oversize; wherein the curved screened combined media is divided into two parts by a diverter, a part of the curved screened combined media and the de-mediation screened combined media are sent to the combined media barrel together, and the remaining curved screened combined media are diverted and sent to the thin media barrel together with the de-mediation screened thin media, and the screened oversize is used as a clean coal product after dehydration;

[0034] Step b 2 , de-mediumizing the fine and medium coal: in step a, the fine and medium coal is de-mediumized by a curved screen and a de-mediumizing screen to obtain a curved screen combined medium, a de-mediumizing screen combined medium, a de-mediumizing screen thin medium and a screen oversize; wherein the curved screen combined medium and the de-mediumizing screen combined medium are de-mediumized; the de-mediumizing screen thin medium is de-mediumized by magnetic separation, and the screen oversize is dehydrated as a medium coal product;

[0035] Step b 3 , the final gangue is removed: in step a, the final gangue is removed by an arc screen and a removal screen to obtain an arc screen combined medium, a removal screen combined medium, a removal screen dilute medium and a screen oversize; wherein the arc screen combined medium and the removal screen combined medium are removed from the combined medium barrel; the removal screen dilute medium is removed from the gangue by magnetic separation, and the screen oversize is used as the gangue product;

[0036] Step c, rare earth classification and sorting: b 1 The arc-shaped screen combined medium splitting and the de-screened thin medium in the step are pumped to the two-stage three-product coal slime heavy medium cyclone group for graded sorting after being buffered by the thin medium barrel to obtain overflow products, coarse clean coal (mid-stream) and coarse medium coal (bottom stream);

[0037] Step d 1, coarse clean coal de-mediation: in step c, the coarse clean coal is fed into a curved screen for de-mediation to obtain an oversize and undersize mixed medium; the oversize is subjected to a clean coal magnetic separation operation, and the undersize mixed medium is diverted, and the ratio of the de-mixing barrel or the clean coal magnetic separator is adjusted according to the coal quality, separation density, and suspension characteristics;

[0038] Step d 2 , Coarse and medium coal de-mediation: In step c, the coarse and medium coal is fed into a curved screen for de-mediation to obtain oversize and undersize mixed media, the oversize is sent to the medium coal magnetic separation operation, and the undersize mixed media is sent to the mixed media barrel;

[0039] Step e 1 , Magnetic separation of overflow products: The overflow products in step c are fed into the overflow magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tail; the magnetic concentrate is split, and the ratio of the decomposition medium barrel and the dilution medium barrel is adjusted according to the density of the dilution medium barrel, and the magnetic tail is used as coal slime water for subsequent concentration operations;

[0040] Step e 2 , Clean coal magnetic separation: step d 1 The material on the middle screen and part of the mixed medium under the screen are fed into the clean coal magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tail; the magnetic concentrate is the same as step e. 1 After the medium magnetic fines are combined, a split flow is set up, and the ratio of the decomposition medium barrel and the dilute medium barrel is adjusted according to the density of the dilute medium barrel; the magnetic tail is used as a coarse clean coal slime product after classification and dehydration; when the feed concentration of the clean coal magnetic separator is too high, water spraying can be increased;

[0041] Step e 3 , Coal Magnetic Separation: Step b 2 Medium removal screening and thinning, step d 2 The material on the middle arc screen is fed into the medium coal magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tailings; the magnetic concentrate goes to the mixing barrel, and the magnetic tailings are graded and dehydrated as coarse medium coal slime products;

[0042] Step e 4 , Gangue magnetic separation: step b 3 The medium-removed medium is fed into the gangue magnetic separator, and magnetic separation is performed to obtain magnetic concentrate and magnetic tailings; the magnetic concentrate goes to the combined medium barrel, and the magnetic tailings are used as tail coal products after dehydration;

[0043] Step f, mixing barrel: Step b 1 Middle arc screen (de-screening) and de-screening, step b 2 、b 3 Middle arc screen and stripping screen, step d 1 Medium sieve under the medium (removal of medium), step d 2 Middle sieve and medium, step e 1 、e 2 Medium magnetic concentrate (removal of medium), step e 3 、e 4The supplementary magnetite powder and water are fed into the combined medium barrel, and the circulating medium is returned to step a by pumping after buffering;

[0044] Step g, dilution barrel preparation: b 1 In step e, the arc screen combines the media flow and the media removal screen to dilute the media. 1 、e 2 The medium magnetic concentrate (removing the diluent) is fed into the diluent barrel and returned to step c after buffering.

[0045] like Figure 2 As shown in the figure, taking a coal preparation plant with a production scale of 3 million tons / year as an example, this process is further described in detail in combination with the equipment connection diagram. Clean coal, medium coal, and gangue are de-intermediated by 2, 1, and 1 linear vibrating screens respectively; overflow, clean coal, medium coal, and gangue are all recovered by 1 magnetic separator, and the second-stage clean coal and second-stage medium coal are de-intermediated by 2 and 1 arc screens respectively.

[0046] Selected raw coal 1 (~80mm) in qualified medium 33 1 , 33 2 Under the action of the cyclone, the three products are separated in the non-demuding heavy medium cyclone A to obtain fine clean coal 2, fine medium coal 3 and fine gangue 4.

[0047] Fine coal 2 passes through curved screen B 1 and descrete C 1 The media is stripped to obtain an arc-shaped screened medium 6, stripped screened medium 8, stripped screened medium 9 and screened material 10. The arc-shaped screened medium 6 is divided into two fixed parts by a diverter D, and the part of the screened medium 7 1 Remove the medium bucket E 2 , part of the combined media diversion 7 2 De-thinning bucket E 1 . De-screening media 8 and partial media 7 1 Go to the combined bucket E 2 ; Remove the media, screen the media, dilute the media 9 and separate the media 7 2 Go to the dilution bucket E 1 The screen material 10 is dehydrated and used as a clean coal product.

[0048] The fine coal 3 passes through the curved screen B 2 and descrete C 2 Remove the medium and obtain the arc-shaped screen medium 12 1 、Removal of media screening and combination 12 2 , de-screening medium 13 and screen material 14. Curved screen medium 12 1 、Removal of media screening and combination 12 2 Remove the medium bucket E 2 ; The medium-coal magnetic separation operation is carried out by removing the medium-coal from the medium-coal screen 13, and the screen material 14 is dehydrated as the medium-coal product. The final gangue 4 passes through the curved screen B 3 and descrete C 3Remove the medium and obtain the arc-shaped screen medium 16 1 、Removal of media screening and combination 16 2 , de-screening medium 17 and screen material 18. Curved screen medium 16 1 、Removal of media screening and combination 16 2 Remove the medium bucket E 2 ; The medium is removed and the medium is screened 17 to remove the gangue and magnetic separation is performed, and the material on the screen 18 is used as the gangue product.

[0049] Clean coal de-mediating screen thin media 9, arc screen combined media diversion 7 2 Diluted barrel E 1 After buffering, the material 19 is pumped through pump F 1 It is sent to the two-stage three-product coal slime heavy medium cyclone group G for sorting, and the overflow 20, coarse clean coal 21 and coarse medium coal 22 are obtained. The coarse clean coal 21 is fed into the curved screen J for de-mediuming, and the oversize 25 and the undersize combined medium 26 are obtained. The oversize 25 is subjected to the coal magnetic separation operation of the clean coal, and the undersize combined medium 26 is diverted by K. The proportion of 28 (removing the first-stage combined medium barrel) or 27 (removing the clean coal magnetic separation) is adjusted according to the coal quality, sorting density, suspension characteristics, etc. The coarse medium coal 22 is fed into the curved screen H for de-mediuming, and the oversize 34 and the undersize combined medium 35 are obtained. The oversize 34 is subjected to the medium coal magnetic separation operation, and the undersize combined medium 35 is subjected to the first-stage combined medium barrel J. 1 .

[0050] Overflow 20 is fed into overflow magnetic separator I 2 Magnetic separation is performed to obtain magnetic concentrate 23 and magnetic tail 24, and the magnetic tail 24 is used as coal slurry water for subsequent concentration operations; the clean coal arc screen oversize 25 and the second stage combined medium split 27 are fed into the clean coal magnetic separator I 3 Magnetic separation is performed to obtain magnetic concentrate 29 and magnetic tail 30. The magnetic tail 30 is used as a coarse coal slime product after buffering, classification and dehydration. The magnetic concentrate 23 and magnetic concentrate 29 are sent to the diverter L to be divided into two parts. The proportions of 31 (removing the combined medium barrel E2) and 32 (removing the diluted medium barrel E1) are adjusted according to the density of the diluted medium. The medium coal de-mediation screen 13 and the medium coal arc screen sieve 34 are sent to the medium coal magnetic separator I1 for magnetic separation to obtain magnetic concentrate 36 and magnetic tail 37. Magnetic concentrate 33 is removed from the first mixed medium barrel E 2 The magnetic tail 37 is graded and dehydrated as a coarse and medium coal slime product. The gangue de-mediating screen 17 is fed into the gangue magnetic separator I4, and magnetic separation is performed to obtain magnetic concentrate 38 and magnetic tail 39. The magnetic concentrate 38 is sent to the first stage of the combined media barrel E 1 , the magnetic tail 39 is used as the tail coal product after buffering and dehydration.

[0051] The above arc screen combination 7 1 , 12 1 , 16 1 , a stage of de-intermediate screening 8, 12 2 , 16 2, the second stage clean coal medium 28, the second stage medium coal medium 35, the magnetic concentrate 31, 36, 38, the supplementary magnetite powder and water are fed into the first stage medium barrel E1 as the circulating medium 33. The circulating medium 33 (including 33 1 , 33 2 Two parts) through pump F 2 Return to the non-pressure three-product heavy medium cyclone A.

[0052] In view of the outstanding problems of the existing non-de-sliming fine coal heavy medium separation process, such as poor coarse coal slime separation, fluctuation of magnetic separation feed, large medium system load, and high medium consumption, a non-de-sliming fine coal heavy medium separation process with low medium consumption, stable operation, and low cost is provided from the perspective of improving coarse coal slime separation and medium recovery. This process separates the fine clean coal fixed mixed medium and the under-screen dilute medium in the three-product coal slime heavy medium cyclone group for graded separation, integrating medium graded recovery, efficient coarse coal slime separation, and stable and reduced clean coal magnetic separation operation load. It not only improves the separation accuracy and flexibility of coarse coal slime, but also improves the efficiency of clean coal magnetic separation, strengthens the recovery of ultra-fine medium, and greatly reduces medium loss.

[0053] The above description shows and describes several preferred embodiments of the invention, but as mentioned above, it should be understood that the invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the invention concept described herein through the above teachings or the technology or knowledge of the relevant field. Changes and modifications made by those skilled in the art should be within the scope of protection of the claims attached to the invention without departing from the spirit and scope of the invention.

Claims

1. A heavy medium separation process for non-de-slimed fine coal based on dilute medium classification separation, characterized in that: Follow the steps below to implement it: Step a, fine raw coal sorting: the fine raw coal with a particle size of no more than 50 mm is sorted in a three-product fine coal heavy medium cyclone under the action of a qualified medium to obtain fine clean coal, fine medium coal and fine gangue; Step b1, fine clean coal de-mediation: in step a, the fine clean coal is de-mediated by a curved screen and a de-mediation screen to obtain curved screen combined media, de-mediation screen combined media, de-mediation screened thin media and screened oversize; wherein the curved screened combined media is divided into two parts by a diverter, one part of the curved screened combined media and the de-mediation screened combined media are sent to the combined media barrel together, and the remaining curved screened combined media are diverted and sent to the thin media barrel together with the de-mediation screened thin media, and the screened oversize is used as a clean coal product after dehydration; Step b2, de-mediumizing the fine and medium coal: the fine and medium coal in step a is de-mediumized by a curved screen and a de-mediumizing screen to obtain a curved screen combined medium, a de-mediumizing screen combined medium, a de-mediumizing screen thin medium and a screen oversize; wherein the curved screen combined medium and the de-mediumizing screen combined medium are de-mediumized; the de-mediumizing screen thin medium is de-mediumized by magnetic separation, and the screen oversize is dehydrated as a medium coal product; Step b3, removing the medium from the final gangue: in step a, the final gangue is removed by passing through an arc screen and a stripping screen to obtain arc screen combined medium, stripping screen combined medium, stripping screen rare medium and screen oversize; wherein the arc screen combined medium and stripping screen combined medium are removed from the combined medium barrel; the stripping screen rare medium is subjected to a gangue magnetic separation operation, and the screen oversize is used as the gangue product; Step c, dilute medium classification and sorting: the arc screen combined medium diversion and the de-medium screen dilute medium in step b1 are pumped to the two-stage three-product coal slime heavy medium cyclone group for classification and sorting after being buffered in the dilute medium barrel to obtain overflow product, coarse clean coal and coarse medium coal; Step d1, de-mediation of coarse clean coal: the coarse clean coal in step c is fed into a curved screen for de-mediation to obtain an oversize and undersize mixed medium; the oversize is subjected to a clean coal magnetic separation operation, and the undersize mixed medium is diverted, and the ratio of the de-mixing barrel or the clean coal magnetic separator is adjusted according to the coal quality, separation density, and suspension characteristics; Step d2, de-mediation of coarse and medium coal: the coarse and medium coal in step c is fed into a curved screen for de-mediation to obtain oversize and undersize mixed media, the oversize is sent to the medium coal magnetic separation operation, and the undersize mixed media is sent to the mixed media barrel; Step e1, magnetic separation of overflow products: the overflow products in step c are fed into the overflow magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tail; the magnetic concentrate is split, and the ratio of the decomposition medium barrel and the dilution medium barrel is adjusted according to the density of the dilution medium barrel, and the magnetic tail is used as coal slime water for subsequent concentration operation; Step e2, clean coal magnetic separation: the oversize and part of the undersize mixed medium in step d1 are fed into the clean coal magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tailings; the magnetic concentrate is combined with the magnetic concentrate in step e1 and a split flow is set, and the ratio of the mixed medium bucket to the dilute medium bucket is adjusted according to the density of the dilute medium bucket; the magnetic tailings are graded and dehydrated as a coarse clean coal slime product; when the feed concentration of the clean coal magnetic separator is too high, water spraying can be increased; Step e3, medium coal magnetic separation: the medium removed from step b2 and the material on the curved screen from step d2 are fed into a medium coal magnetic separator for magnetic separation to obtain magnetic concentrate and magnetic tail; the magnetic concentrate is sent to the combined medium barrel, and the magnetic tail is graded and dehydrated to be a coarse medium coal slime product; Step e4, gangue magnetic separation: the de-screened and thinned media in step b3 is fed into the gangue magnetic separator, and magnetic separation is performed to obtain magnetic concentrate and magnetic tailings; the magnetic concentrate is sent to the combined media barrel, and the magnetic tailings are used as tail coal products after dehydration; Step f, mixing the combined medium barrel: a part of the arc-shaped screened combined medium and the de-screened combined medium in step b1, the arc-shaped screened combined medium and the de-screened combined medium in steps b2 and b3, a part of the under-screened combined medium in step d1, the under-screened combined medium in step d2, a part of the magnetic concentrate in step e1, a part of the magnetic concentrate in step e2, the magnetic concentrate in steps e3 and e4, the supplemented magnetite powder and water are fed into the combined medium barrel, and the circulating medium is returned to step a by pumping after buffering; Step g, preparation of the dilution barrel: another part of the arc-shaped screened medium and the de-screened dilution medium in step b1, another part of the magnetic concentrate in step e1, and another part of the magnetic concentrate in step e2 are fed into the dilution barrel, and returned to step c after buffering.

2. The heavy medium separation process of non-de-slimed fine coal based on dilute medium classification separation according to claim 1 is characterized by: In the step b1, the combined flow rate of the thinning medium bucket is a fixed value, which is determined according to the fine coal sorting density and the coal slime content, and is set between 25% and 35%.

3. The heavy medium separation process of non-de-slimed fine coal based on dilute medium classification separation according to claim 1 is characterized by: In the step c, the feed pressure of the three-product coal slime heavy medium cyclone group is between 0.1 and 0.15 MPa.

4. The heavy medium separation process of non-de-slimed fine coal based on dilute medium classification separation according to claim 1 is characterized by: In step c, the three-product coal slime heavy medium cyclone unit is composed of two sections of two-product small diameter cyclones arranged in series and in parallel, one section is cylindrical and the second section is conical, the cone angle of the two sections is 15° to 20°, and the installation angle is 10° to 15°.

5. The heavy medium separation process of non-de-slimed fine coal based on dilute medium classification separation according to claim 1, characterized in that: In the step e2, the amount of water sprayed is determined according to the feed concentration of the clean coal magnetic separator, and the mass concentration is between 15% and 25%.

6. The heavy medium separation process of non-de-slimed fine coal based on dilute medium classification separation according to claim 1, characterized in that: In the step e1, the magnetic field strength of the overflow magnetic separator is 2200-2500 GS, and the magnetic field strength of the magnetic separator in steps e2, e3, and e4 is 1500-1800 GS.

7. The heavy medium separation process of non-de-slimed fine coal based on dilute medium classification separation according to claim 1 is characterized by: In the step f, the density of the combined medium barrel is controlled to target the first stage separation of the three-product fine coal heavy medium cyclone, and is determined according to the ash content and coal quality of the fine coal, and is generally between 1.35 and 1.45 kg / L.

8. The heavy medium separation process for non-de-slimed fine coal based on dilute medium classification separation according to claim 1, characterized in that: In the step g, the density of the dilute medium barrel is controlled to target the second-stage separation of the three-product coal slime heavy medium cyclone, and is determined according to the ash content and coal quality of the coarse and fine coal slime, and is generally between 1.10 and 1.20 kg / L.

Images