Coal whole-size-fraction three-product fine separation process

Abstract

The invention discloses a coal full-size-fraction three-product fine separation process which comprises the following steps: passing selected raw coal through a classifying screen to obtain first-size-fraction raw coal and second-size-fraction raw coal; the second-size-fraction raw coal enters an intelligent dry separation system, and lump clean coal, lump middling coal and lump gangue are obtained; the first-size-fraction raw coal and the block clean coal pass through a desliming screen, and third-size-fraction raw coal and fourth-size-fraction raw coal are obtained; the third-size-fraction raw coal passes through a classification cyclone, and fine coal slime and coarse coal slime are obtained; fine coal slime passes through the flotation system, coarse coal slime is separated by the three-product spiral separation system, and fourth-fraction raw coal is separated by the three-product dense medium cyclone system. The multi-particle-size raw coal is separated, full-fraction three-product fine separation of the raw coal with the particle size smaller than 300 mm is achieved, clean coal, middling coal and gangue are separated out at the same time, the separation precision and quality indexes are met, meanwhile, the clean coal recovery rate can be increased, coal resources can be fully recovered, and the economic benefits of enterprises are increased.

Description

Technical Field

[0001] The invention relates to the technical field of coal sorting, and in particular to a three-product fine sorting process for all-grade coal. Background Art

[0002] Coal is the main energy source in my country, accounting for more than 70% of primary energy. Since my country's coal resources are more abundant than oil and natural gas resources, my country cannot easily change the primary energy production and consumption structure dominated by coal for a long time in the future. Washing and reprocessing of mined raw coal plays a vital role in the process of coal production and efficient utilization, and is the basis and prerequisite for achieving clean utilization of coal, energy conservation and emission reduction, and sustainable and healthy development.

[0003] In recent years, with the increasing degree of mechanization in coal mining in my country, the content of gangue and fine particles mixed in raw coal has gradually increased, and the quality of raw coal has shown a downward trend. Under the current background of dual carbon development, users have put forward higher requirements for the quality of coal products, and need to achieve high-quality coal energy supply through efficient and fine coal sorting. Therefore, the coal full-particle sorting process technology has received more and more attention from domestic and foreign coal preparation workers. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the above-mentioned prior art and to provide a process for fine sorting of three products of coal of all particle sizes. The present invention achieves fine sorting of three products of coal of all particle sizes of 0-300 mm by separately sorting coal slimes with multiple particle sizes, and simultaneously sorts out three products of clean coal, medium coal and gangue. While meeting the sorting accuracy and quality indicators, it can improve the recovery rate of clean coal, fully recover coal resources and increase the economic benefits of the enterprise.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a three-product fine separation process of all-grade coal, comprising the following steps:

[0006] (a) First raw coal screening: The selected raw coal is screened by a grading screen to obtain first-grade raw coal and second-grade raw coal;

[0007] (b) Second-grade raw coal sorting: The second-grade raw coal in step a enters the intelligent dry sorting system to obtain clean coal, medium coal and gangue. The medium coal enters the medium coal bin, and the gangue enters the gangue bin;

[0008] (c) Secondary raw coal screening: the first-grade raw coal in step a and the lump clean coal in step b are mixed and screened through a desludging screen to obtain third-grade raw coal and fourth-grade raw coal;

[0009] (d) Third raw coal screening: the third particle size raw coal in step c is sorted by a grading cyclone to obtain fine coal slime and coarse coal slime;

[0010] (e1) fine coal slime sorting: the fine coal slime described in step d is sorted by a flotation system to obtain floating fine coal slime, floating medium coal slime and floating tail coal slime. The floating fine coal slime enters the clean coal bin, the floating medium coal slime enters the medium coal bin, and the floating tail coal slime enters the gangue bin;

[0011] (e2) Coarse coal slime sorting: the coarse coal slime described in step d is sorted by a three-product spiral sorting system to obtain coarse clean coal, coarse medium coal and coarse gangue. The coarse clean coal enters the clean coal bin, the coarse medium coal enters the medium coal bin, and the coarse gangue enters the gangue bin;

[0012] (f) Sorting of the fourth-grade raw coal: The fourth-grade raw coal described in step c is passed through a three-product heavy medium cyclone system to obtain fine clean coal, fine medium coal, fine gangue and qualified medium. The fine clean coal enters the clean coal bin, the fine medium coal enters the medium coal bin, the fine gangue enters the gangue bin, and the qualified medium enters the combined medium barrel.

[0013] Preferably, the step of the second-grade raw coal entering the intelligent dry separation system comprises:

[0014] (b1) Coal crushing: the second-grade raw coal enters a through-type crusher, and the through-type crusher crushes the second-grade raw coal to a size of less than 300 mm, thereby obtaining the second-grade raw coal with a particle size of less than 300 mm;

[0015] (b2) roller sieve screening: the second-grade raw coal with a particle size of less than 300 mm in step b1 is screened by a roller sieve to obtain raw coal with a particle size of less than 50 mm and raw coal with a particle size of more than 50 mm, and the raw coal with a particle size of less than 50 mm is mixed with the first-grade raw coal;

[0016] (b3) Sorting by intelligent dry sorting machine: The raw coal with a particle size greater than 50 mm in step b2 is subjected to an intelligent dry sorting machine to obtain clean coal lumps, medium coal lumps and gangue lumps. The clean coal lumps are crushed by a crusher into clean coal lumps with a particle size less than 50 mm.

[0017] Preferably, the step of the fine coal slime entering the flotation system comprises:

[0018] (e 101 ) Coal slime flotation: the fine coal slime enters the flotation machine for sorting to obtain flotation clean coal, flotation coal and flotation tailings;

[0019] (e 102 ) Flotation clean coal filtration: step e 101 The flotation clean coal is filtered through a first filter press to obtain flotation clean coal slime;

[0020] (e 103 ) Filter pressing of coal in flotation: step e 101 The flotation coal is filtered through a second filter press to obtain floating coal slime;

[0021] (e 104 ) Flotation tailings filtration: step e 101 The flotation tail coal is passed through a concentrator and a third filter press to obtain floating tail coal slime.

[0022] Preferably, the step of the coarse coal slime entering the three-product spiral separation system comprises:

[0023] (e 201 ) Sorting coal slime: The coarse coal slime is separated by a three-product spiral separator to obtain coarse clean coal slime, coarse medium coal slime and coarse gangue slime;

[0024] (e 202 ) Dehydration of coarse coal slime: Step e 201 The coarse clean coal slime is dehydrated by the first curved screen and the first centrifuge to obtain coarse clean coal;

[0025] (e 203 ) Dehydration of coarse and medium coal slime: Step e 201 The coarse and medium coal slime is dehydrated by the second curved screen and the first high-frequency screen to obtain the coarse and medium coal slime;

[0026] (e 204 ) Dehydration of coarse gangue mud: Step e 201 The coarse gangue mud is dehydrated by the third curved screen and the second high-frequency screen to obtain coarse gangue.

[0027] Preferably, the step of the fourth-grade raw coal entering the three-product heavy medium cyclone system comprises:

[0028] (f1) Coal slime separation: the fourth-grade raw coal is passed through a three-product heavy medium cyclone to obtain fine clean coal, fine medium coal and fine gangue;

[0029] (f2) Fine clean coal demediation: The fine clean coal in step f1 is passed through a clean coal demediation screen to obtain an oversize, a dilute medium and a qualified medium. The oversize is dehydrated by a second centrifuge to obtain fine clean coal and enter the clean coal bin. The dilute medium is magnetically separated by a first magnetic separator to obtain magnetic concentrate and a magnetic tail. The magnetic concentrate and the qualified medium enter a combined medium barrel, and the magnetic tail enters a grading cyclone.

[0030] (f3) Removal of fine and medium coal: The fine and medium coal in step f1 is passed through a medium coal removal screen to obtain an oversize, a dilute medium and a qualified medium. The oversize is dehydrated by a third centrifuge to obtain fine and medium coal, which enters a medium coal bin. The dilute medium is magnetically separated by a second magnetic separator to obtain a magnetic concentrate and a magnetic tail. The magnetic concentrate and the qualified medium enter a combined medium barrel, and the magnetic tail enters a grading cyclone.

[0031] (f4) Removal of fine gangue: The fine gangue described in step f1 is passed through a gangue removal screen to obtain fine gangue, dilute medium and qualified medium. The dilute medium is magnetically separated by a third magnetic separator to obtain magnetic concentrate and magnetic tail. The magnetic concentrate and qualified medium enter the combining barrel, the magnetic tail enters the classifying cyclone, and the fine gangue enters the gangue bin.

[0032] Preferably, the sieve hole of the grading screen is 50 mm, the first particle size raw coal is the undersize of the grading screen, the particle size of the first particle size raw coal is less than 50 mm, and the second particle size raw coal is the oversize of the grading screen, the particle size of the second particle size raw coal is greater than 50 mm.

[0033] Preferably, the sieve hole of the desliming screen is 1 mm, the third grade raw coal is the undersize of the desliming screen, the particle size of the third grade raw coal is less than 1 mm, the fourth grade raw coal is the oversize of the desliming screen, and the particle size of the fourth grade raw coal is 1-50 mm.

[0034] Preferably, the particle size of the fine coal slime is less than 0.25 mm, and the particle size of the coarse coal slime is 0.25-1 mm.

[0035] Preferably, the three-product heavy medium cyclone produces secondary coal slime with a particle size less than 1 mm due to the high feed pressure, and the secondary coal slime with a particle size less than 1 mm is fed into a classifying cyclone.

[0036] Compared with the prior art, the present invention has the following advantages:

[0037] 1. The present invention separates the coal slimes with different particle sizes and realizes fine sorting of three products of all particle sizes for the coal slimes with particle sizes less than 300 mm, and simultaneously sorts out three products of clean coal, medium coal and gangue. While meeting the sorting accuracy and quality indicators, it can improve the clean coal recovery rate, fully recover coal resources, and increase the economic benefits of the enterprise.

[0038] 2. The present invention performs multi-stage screening on raw coal, firstly screens the raw coal into raw coal with a particle size less than 50 mm and raw coal with a particle size greater than 50 mm, then crushes and screens the raw coal with a particle size greater than 50 mm, and divides it into raw coal with a particle size less than 50 mm and raw coal with a particle size greater than 50 mm, sorts the raw coal with a particle size greater than 50 mm, and crushes the sorted clean coal into raw coal with a particle size less than 50 mm by a crusher, screens all the raw coal with a particle size less than 50 mm, obtains raw coal with a particle size less than 1 mm and raw coal with a particle size of 1-50 mm, and further screens the raw coal with a particle size less than 1 mm into fine coal slime with a particle size less than 0.25 mm and coarse coal slime with a particle size of 0.25-1 mm, and reduces the doping rate of coal slime through multi-stage screening.

[0039] The present invention is further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 is a process flow chart of the present invention;

[0041] Figure 2 It is a device relationship connection diagram of the present invention.

[0042] Description of reference numerals:

[0043] A—grading screen; B—crusher; C—roller screen;

[0044] D—de-sludging screen; E—intelligent dry separator; F—middle coal bunker;

[0045] G—gangue bin; H—three-product heavy medium cyclone;

[0046] I1—clean coal de-mediation screen; I2—medium coal de-mediation screen; I3—gangue de-mediation screen;

[0047] J1—second centrifuge; J2—third centrifuge; J3—first centrifuge;

[0048] K—clean coal bin; L1—first magnetic separator; L2—second magnetic separator;

[0049] L3—the third magnetic separator; M—combination chamber; N—classification cyclone;

[0050] O1—first filter press; O2—second filter press; O3—third filter press;

[0051] P—thickener; Q1—first curved screen; Q2—second curved screen;

[0052] Q3—the third curved screen; R1—the first high-frequency screen; R2—the second high-frequency screen;

[0053] S—crusher; T—flotation machine;

[0054] U—Three-product spiral separator. DETAILED DESCRIPTION

[0055] like Figure 1 As shown, the present invention discloses a three-product fine separation process of coal of all particle sizes, comprising the following steps:

[0056] (a) First raw coal screening: The selected raw coal is screened by a grading screen to obtain first-grade raw coal and second-grade raw coal;

[0057] The sieve hole of the grading screen is 50mm, the first grade raw coal is the undersize of the grading screen, and the particle size of the first grade raw coal is less than 50mm, and the second grade raw coal is the oversize of the grading screen, and the particle size of the second grade raw coal is greater than 50mm.

[0058] (b) Second-grade raw coal sorting: The second-grade raw coal in step a enters the intelligent dry sorting system to obtain clean coal, medium coal and gangue. The medium coal enters the medium coal bin, and the gangue enters the gangue bin;

[0059] The steps for the second-grade raw coal to enter the intelligent dry separation system include:

[0060] (b1) Coal crushing: The second-grade raw coal enters the through-type crusher, which crushes the second-grade raw coal to less than 300 mm, thereby obtaining the second-grade raw coal with a particle size of less than 300 mm;

[0061] (b2) Roller sieve screening: The second-grade raw coal with a particle size of less than 300 mm in step b1 is screened by a roller sieve to obtain raw coal with a particle size of less than 50 mm and raw coal with a particle size of more than 50 mm. The raw coal with a particle size of less than 50 mm is mixed with the first-grade raw coal.

[0062] The sieve hole of the roller screen plate is 50 mm. Furthermore, the roller screen can also be a relaxation screen.

[0063] (b3) Sorting by intelligent dry sorting machine: The raw coal with a particle size greater than 50 mm in step b2 is processed by an intelligent dry sorting machine to obtain clean coal, medium coal and gangue. The clean coal is crushed by a crusher into clean coal with a particle size less than 50 mm.

[0064] The clean coal with particle size less than 50mm is mixed with the first-grade raw coal and enters the desludging screen, the medium coal enters the medium coal bin, and the gangue enters the gangue bin.

[0065] (c) Second raw coal screening: the first-grade raw coal in step a and the lump clean coal in step b are mixed and screened through a desludging screen to obtain third-grade raw coal and fourth-grade raw coal;

[0066] The mesh of the desliming screen is 1mm, the third grade raw coal is the undersize of the desliming screen, the particle size of the third grade raw coal is less than 1mm, the fourth grade raw coal is the oversize of the desliming screen, the particle size of the fourth grade raw coal is 1-50mm. The desliming screen with a mesh of 1mm is selected to facilitate the desliming of the coal slime by the desliming screen, and improve the sorting efficiency and sorting accuracy of the oversize of the desliming screen after entering the three-product heavy medium cyclone.

[0067] (d) Third raw coal screening: The third-grade raw coal in step c is sorted by a grading cyclone to obtain fine coal slime and coarse coal slime;

[0068] The particle size of fine coal slime is less than 0.25mm, and the particle size of coarse coal slime is 0.25-1mm.

[0069] (e1) fine coal slime separation: the fine coal slime in step d is separated by a flotation system to obtain floating fine coal slime, floating medium coal slime and floating tail coal slime. The floating fine coal slime enters the clean coal bin, the floating medium coal slime enters the medium coal bin, and the floating tail coal slime enters the gangue bin;

[0070] The steps of fine coal slime entering the flotation system include:

[0071] (e 101 ) Coal slime flotation: fine coal slime enters the flotation machine for sorting, and obtains flotation clean coal, flotation coal and flotation tailings;

[0072] (e 102 ) Flotation clean coal filtration: step e 101 The medium flotation clean coal is filtered through the first filter press to obtain flotation clean coal slime;

[0073] (e 103 ) Filter pressing of coal in flotation: step e 101 The coal in the flotation is filtered by the second filter press to obtain the floating coal slime;

[0074] (e 104 ) Flotation tailings filtration: step e 101 The tail coal from the flotation is passed through a thickener and the third filter press to obtain floating tail coal slime.

[0075] (e2) Coarse coal slime sorting: The coarse coal slime in step d is sorted by a three-product spiral sorting system to obtain coarse clean coal, coarse medium coal and coarse gangue. The coarse clean coal enters the clean coal bin, the coarse medium coal enters the medium coal bin, and the coarse gangue enters the gangue bin.

[0076] The steps of coarse coal slime entering the three-product spiral separation system include:

[0077] (e 201 ) Sorting coal slime: The coarse coal slime is separated by a three-product spiral separator to obtain coarse clean coal slime, coarse medium coal slime and coarse gangue slime;

[0078] (e 202 ) Dehydration of coarse coal slime: Step e 201 The medium-coarse clean coal slime is dehydrated by the first curved screen and the first centrifuge to obtain coarse clean coal;

[0079] The curved screen can also be a laminated screen, an electromagnetic screen or a high-frequency screen.

[0080] (e 203 ) Dehydration of coarse and medium coal slime: Step e 201 The medium-coarse medium coal slime is dehydrated by the second curved screen and the first high-frequency screen to obtain the coarse medium coal slime;

[0081] (e 204 ) Dehydration of coarse gangue mud: Step e 201 The medium-coarse gangue mud is dehydrated by the third curved screen and the second high-frequency screen to obtain coarse gangue.

[0082] (f) Sorting of the fourth-grade raw coal: The fourth-grade raw coal in step c passes through the three-product heavy medium cyclone system to obtain fine clean coal, fine medium coal, fine gangue and qualified medium. The fine clean coal enters the clean coal bin, the fine medium coal enters the medium coal bin, the fine gangue enters the gangue bin, and the qualified medium enters the combined medium barrel.

[0083] The third-product heavy medium cyclone produces secondary coal slime with a particle size less than 1 mm due to the high feed pressure, and the secondary coal slime with a particle size less than 1 mm is sent to the classifying cyclone.

[0084] The steps for the fourth-grade raw coal to enter the three-product heavy medium cyclone system include:

[0085] (f1) Coal slime separation: The fourth-grade raw coal is passed through a three-product heavy medium cyclone to obtain fine clean coal, fine medium coal and fine gangue;

[0086] (f2) Removal of fine clean coal: In step f1, the fine clean coal is passed through a clean coal removal screen to obtain an oversize, a dilute medium and a qualified medium. The oversize is dehydrated by a second centrifuge to obtain fine clean coal, which enters a clean coal bin. The dilute medium is magnetically separated by a first magnetic separator to obtain a magnetic concentrate and a magnetic tail. The magnetic concentrate and the qualified medium enter a combined medium barrel, and the magnetic tail enters a grading cyclone.

[0087] (f3) Removal of fine and medium coal: In step f1, the fine and medium coal is passed through a medium coal removal screen to obtain an oversize, a dilute medium and a qualified medium. The oversize is dehydrated by a third centrifuge to obtain fine and medium coal, which enters a medium coal bin. The dilute medium is magnetically separated by a second magnetic separator to obtain a magnetic concentrate and a magnetic tail. The magnetic concentrate and the qualified medium enter a medium combining barrel, and the magnetic tail enters a classifying cyclone.

[0088] (f4) Removal of fine gangue: In step f1, the fine gangue is screened by the gangue removal screen to obtain fine gangue, dilute medium and qualified medium. The dilute medium is magnetically separated by the third magnetic separator to obtain magnetic concentrate and magnetic tail. The magnetic concentrate and qualified medium enter the combining barrel, the magnetic tail enters the classifying cyclone, and the fine gangue enters the gangue bin.

[0089] The magnetic concentrate and qualified medium in the combined medium barrel enter the third-product heavy medium cyclone for sorting again; the magnetic tail enters the classification cyclone and is sorted into fine coal slime and coarse coal slime together with the third-grade raw coal through the classification cyclone.

[0090] like Figure 2 As shown, the present invention is described in detail through a device connection diagram.

[0091] The selected raw coal 1 (coal slime with a particle size of less than 300mm) is screened by a grading screen A with a mesh size of 50mm to obtain first-grade raw coal 2 and second-grade raw coal 3. The second-grade raw coal 3 enters a through-type crusher B, which crushes the second-grade raw coal 3 to a particle size of less than 300mm. The crushed second-grade raw coal 3 is screened by a roller screen C with a mesh size of 50mm to obtain raw coal 4 with a particle size of less than 50mm and raw coal 5 with a particle size of 50-300mm. The raw coal 4 with a particle size of less than 50mm and the first-grade raw coal 2 both enter a desliming screen D with a mesh size of 1mm, and the raw coal 5 with a particle size of 50-300mm enters the intelligent dry separation. The machine E selects clean coal 6, medium coal 7 and gangue 8. The medium coal 7 goes to the medium coal bin F, and the gangue 8 goes to the gangue bin G. The clean coal 6 is crushed into raw coal with a particle size less than 50 mm by the crusher S, and the crushed clean coal 6 is sent to the desliming screen D. The desliming screen D screens the first-grade raw coal 2, the raw coal 4 with a particle size less than 50 mm and the crushed clean coal 6 to obtain the third-grade raw coal 9 and the fourth-grade raw coal 10. The fourth-grade raw coal 10 enters the three-product heavy medium cyclone H for sorting to obtain fine clean coal slime 11, fine medium coal slime 12 and fine gangue slime 13. At the same time, due to the high feeding pressure of the three-product heavy medium cyclone H, the particle size is less than 1 m. m secondary coal slime 14, the secondary coal slime 14 is sent to the grading cyclone N for sorting, the fine clean coal slime 11 is de-mediumed by the clean coal de-medium screen I1 to obtain the screen material 151, the dilute medium 161 and the qualified medium 171, the screen material 151 is dehydrated by the second centrifuge J1 to obtain the fine clean coal 20, the fine clean coal 20 enters the clean coal bin K, the dilute medium 161 enters the first magnetic separator L1 for magnetic separation to obtain the magnetic fine 181 and the magnetic tail 191, the magnetic fine 181 and the qualified medium 171 enter the combined medium barrel M, the fine medium coal slime 12 is de-mediumed by the medium coal de-medium screen I2 to obtain the screen material 152, the dilute medium 162 and the qualified medium 172, the screen material 152 is dehydrated by the third centrifuge After dehydration by machine J2, fine medium coal 21 is obtained, which enters the medium coal bin F, and the dilute medium 162 enters the second magnetic separator L2 for magnetic separation to obtain magnetic concentrate 182 and magnetic tail 192. The magnetic concentrate 182 and qualified medium 172 enter the combining barrel M, and the fine gangue mud 13 is de-mediumed by the gangue de-medium screen I3 to obtain oversize 153, dilute medium 163 and qualified medium 173. The oversize 153 enters the gangue bin G, and the dilute medium 163 enters the third magnetic separator L3 for magnetic separation to obtain magnetic concentrate 183 and magnetic tail 193. The magnetic concentrate 183 and qualified medium 173 enter the combining barrel M, and the magnetic tails 191, 192, and 193 all enter the three-product heavy medium cyclone for sorting.

[0092] At the same time, the grading cyclone N sorts the third-grade raw coal 9 and the secondary coal slime 14 to obtain fine coal slime 22 and coarse coal slime 23. The fine coal slime 22 enters the flotation machine T for flotation to obtain flotation clean coal 24, flotation medium coal 25 and flotation tail coal 26. The flotation clean coal 24 is filtered by the first filter press O1 to obtain floating clean coal slime 241, which enters the clean coal bin K. The flotation medium coal 25 is filtered by the second filter press O2 to obtain floating medium coal slime 251, which enters the medium coal bin F. The flotation tail coal 26 enters the concentrator P and the third filter press O3 to obtain floating tail coal slime 261, which enters the gangue bin G. The coarse coal slime 23 enters the three-product spiral separator U for sorting to obtain coarse clean coal slime 27, coarse medium coal slime 28 and coarse gangue slime 29. The coarse clean coal slime 27 enters the first curved screen Q1 and the first centrifuge J3 for dehydration to obtain coarse clean coal 271. The coarse clean coal 271 enters the clean coal bin K. The coarse medium coal slime 28 enters the second curved screen Q2 and the first high-frequency screen R1 for dehydration to obtain coarse medium coal 281. The coarse medium coal 281 enters the medium coal bin F. The coarse gangue slime 29 enters the third curved screen Q3 and the second high-frequency screen R2 for dehydration to obtain coarse gangue 291. The coarse gangue 291 enters the gangue bin G.

[0093] The present invention comprises the following steps: selecting raw coal with a particle size greater than 50 mm by an intelligent dry sorting system, selecting raw coal with a particle size of 1-50 mm by a three-product heavy medium cyclone system, selecting coarse coal slime with a particle size of 0.25-1 mm by a three-product spiral sorting system, and selecting fine coal slime with a particle size less than 0.25 mm by a flotation system; the sorted fine clean coal, coarse clean coal and floating clean coal slime all enter a clean coal bin as final clean coal, and lump medium coal, fine medium coal, coarse medium coal and floating medium coal slime all enter a medium coal bin as final medium coal; lump gangue, fine gangue, coarse gangue and floating tail coal slime all enter a gangue bin as final gangue; and the mixing and blending mode of products of each particle size can also be flexibly adjusted according to product market demand to produce products of different quality specifications. The present invention can realize the fine sorting of three products of all particle sizes of coal with a particle size less than 300 mm, and simultaneously sort out three products of clean coal, medium coal and gangue. While meeting the sorting accuracy and quality indicators, it can improve the clean coal recovery rate, fully recover coal resources, and increase the economic benefits of the enterprise.

[0094] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A three-product fine separation process for all-grade coal, characterized in that: The following steps are involved: (a) First raw coal screening: The selected raw coal is screened by a grading screen to obtain first-grade raw coal and second-grade raw coal; (b) Second-grade raw coal sorting: The second-grade raw coal in step a enters the intelligent dry sorting system to obtain clean coal, medium coal and gangue. The medium coal enters the medium coal bin, and the gangue enters the gangue bin; (c) Secondary raw coal screening: the first-grade raw coal in step a and the lump clean coal in step b are mixed and screened through a desludging screen to obtain third-grade raw coal and fourth-grade raw coal; (d) Third raw coal screening: the third particle size raw coal in step c is sorted by a grading cyclone to obtain fine coal slime and coarse coal slime; (e1) fine coal slime sorting: the fine coal slime described in step d is sorted by a flotation system to obtain floating fine coal slime, floating medium coal slime and floating tail coal slime. The floating fine coal slime enters the clean coal bin, the floating medium coal slime enters the medium coal bin, and the floating tail coal slime enters the gangue bin; (e2) Coarse coal slime sorting: the coarse coal slime described in step d is sorted by a three-product spiral sorting system to obtain coarse clean coal, coarse medium coal and coarse gangue. The coarse clean coal enters the clean coal bin, the coarse medium coal enters the medium coal bin, and the coarse gangue enters the gangue bin; (f) Sorting of the fourth-grade raw coal: The fourth-grade raw coal described in step c is passed through a three-product heavy medium cyclone system to obtain fine clean coal, fine medium coal, fine gangue and qualified medium. The fine clean coal enters the clean coal bin, the fine medium coal enters the medium coal bin, the fine gangue enters the gangue bin, and the qualified medium enters the combined medium barrel.

2. A three-product fine separation process for all-grade coal according to claim 1, characterized in that: The steps of the second-grade raw coal entering the intelligent dry separation system include: (b1) Coal crushing: the second-grade raw coal enters a through-type crusher, and the through-type crusher crushes the second-grade raw coal to a size of less than 300 mm, thereby obtaining the second-grade raw coal with a particle size of less than 300 mm; (b2) roller sieve screening: the second-grade raw coal with a particle size of less than 300 mm in step b1 is screened by a roller sieve to obtain raw coal with a particle size of less than 50 mm and raw coal with a particle size of more than 50 mm, and the raw coal with a particle size of less than 50 mm is mixed with the first-grade raw coal; (b3) Sorting by intelligent dry sorting machine: The raw coal with a particle size greater than 50 mm in step b2 is subjected to an intelligent dry sorting machine to obtain clean coal lumps, medium coal lumps and gangue lumps. The clean coal lumps are crushed by a crusher into clean coal lumps with a particle size less than 50 mm.

3. A three-product fine separation process of coal of all particle sizes according to claim 1, characterized in that: The steps of the fine coal slime entering the flotation system include: (e 101 ) Coal slime flotation: the fine coal slime enters the flotation machine for sorting to obtain flotation clean coal, flotation coal and flotation tailings; (e 102 ) Flotation clean coal filtration: step e 101 The flotation clean coal is filtered through a first filter press to obtain flotation clean coal slime; (e 103 ) flotation coal filtration; step e 101 The flotation coal is filtered through a second filter press to obtain floating coal slime; (e 104 ) Flotation tailings filtration: step e 101 The flotation tail coal is passed through a concentrator and a third filter press to obtain floating tail coal slime.

4. A three-product fine separation process of coal of all particle sizes according to claim 1, characterized in that: The steps of the coarse coal slime entering the three-product spiral separation system include: (e 201 ) Sorting coal slime: The coarse coal slime is separated by a three-product spiral separator to obtain coarse clean coal slime, coarse medium coal slime and coarse gangue slime; (e 202 ) Dehydration of coarse coal slime: Step e 201 The coarse clean coal slime is dehydrated by the first curved screen and the first centrifuge to obtain coarse clean coal; (e 203 ) Dehydration of coarse and medium coal slime: Step e 201 The coarse and medium coal slime is dehydrated by the second curved screen and the first high-frequency screen to obtain the coarse and medium coal slime; (e 204 ) Dehydration of coarse gangue mud: Step e 201 The coarse gangue mud is dehydrated by the third curved screen and the second high-frequency screen to obtain coarse gangue.

5. A three-product fine separation process of coal of all particle sizes according to claim 1, characterized in that: The step of the fourth-grade raw coal entering the three-product heavy medium cyclone system includes: (f1) Raw coal sorting: the fourth-grade raw coal is passed through a three-product heavy medium cyclone to obtain fine clean coal, fine medium coal and fine gangue; (f2) Fine clean coal demediation: The fine clean coal in step f1 is passed through a clean coal demediation screen to obtain an oversize, a dilute medium and a qualified medium. The oversize is dehydrated by a second centrifuge to obtain fine clean coal and enter the clean coal bin. The dilute medium is magnetically separated by a first magnetic separator to obtain magnetic concentrate and a magnetic tail. The magnetic concentrate and the qualified medium enter a combined medium barrel, and the magnetic tail enters a grading cyclone. (f3) Removal of fine and medium coal: The fine and medium coal in step f1 is passed through a medium coal removal screen to obtain an oversize, a dilute medium and a qualified medium. The oversize is dehydrated by a third centrifuge to obtain fine and medium coal, which enters a medium coal bin. The dilute medium is magnetically separated by a second magnetic separator to obtain a magnetic concentrate and a magnetic tail. The magnetic concentrate and the qualified medium enter a combined medium barrel, and the magnetic tail enters a grading cyclone. (f4) Removal of fine gangue: The fine gangue described in step f1 is passed through a gangue removal screen to obtain fine gangue, dilute medium and qualified medium. The dilute medium is magnetically separated by a third magnetic separator to obtain magnetic concentrate and magnetic tail. The magnetic concentrate and qualified medium enter the combining barrel, the magnetic tail enters the classifying cyclone, and the fine gangue enters the gangue bin.

6. A three-product fine separation process for all-grade coal according to claim 1, characterized in that: The sieve hole of the grading screen is 50 mm, the first particle size raw coal is the undersize of the grading screen, and the particle size of the first particle size raw coal is less than 50 mm, and the second particle size raw coal is the oversize of the grading screen, and the particle size of the second particle size raw coal is greater than 50 mm.

7. A three-product fine separation process for all-grade coal according to claim 1, characterized in that: The sieve hole of the desliming screen is 1mm, the third grade raw coal is the undersize of the desliming screen, and the particle size of the third grade raw coal is less than 1mm, the fourth grade raw coal is the oversize of the desliming screen, and the particle size of the fourth grade raw coal is 1-50mm.

8. A three-product fine separation process for all-grade coal according to claim 1, characterized in that: The particle size of the fine coal slime is less than 0.25 mm, and the particle size of the coarse coal slime is 0.25-1 mm.

9. A three-product fine separation process for all-grade coal according to claim 3, characterized in that: The three-product heavy medium cyclone produces secondary coal slime with a particle size less than 1 mm due to the high feed pressure, and the secondary coal slime with a particle size less than 1 mm is sent to the classifying cyclone.

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