CN113289774B

CN113289774B - Coarse slime coal recovery and clean coal system and method

Info

Publication number: CN113289774B
Application number: CN202110533019.2A
Authority: CN
Inventors: 刘水利; 路根奎; 岳东; 霍小泉; 李满平; 李伟辉; 王卫云; 袁增云; 范智海
Original assignee: Shaanxi Shaanxi Coal Tongchuan Mining Co ltd
Current assignee: Shaanxi Shaanxi Coal Tongchuan Mining Co ltd
Priority date: 2021-05-17
Filing date: 2021-05-17
Publication date: 2023-04-11
Anticipated expiration: 2041-05-17
Also published as: CN113289774A

Abstract

The utility model provides a system and a method for recovering clean coal from coarse coal slime, which relates to the technical field of coal production and can recover clean coal from coarse coal slime so as to improve the yield of clean coal. The system comprises a coarse coal slime channel, a dehydration unit, a conveying channel, a screening unit and a clean coal channel, wherein the dehydration unit is communicated with the coarse coal slime channel and the conveying channel; the screening unit is communicated with the conveying channel and the clean coal channel. The method comprises the following steps: the coarse coal slime is dehydrated into dehydrated coal slime through high-speed rotation of a dehydration unit; the dehydrated coal slime enters a screening unit to be mixed with the dispersion liquid, so that particles with different particle sizes in the dehydrated coal slime are uniformly dispersed; the dehydrated coal slime with uniformly dispersed particles is subjected to high-speed rotary screening by a screening unit to obtain clean coal; the clean coal is output by the coarse coal slime recovery clean coal system through the clean coal channel. The coarse coal slime is subjected to dehydration treatment by the dehydration unit and then screening treatment by the screening unit, so that the coarse coal slime generated in the desliming link is used as a raw material to recover clean coal.

Description

Coarse slime coal recovery and clean coal system and method

Technical Field

The disclosure relates to the field of coal production, in particular to a system and a method for recovering clean coal from coarse coal slime.

Background

Along with the improvement of the mechanization degree of coal mining, the content of coal slime in selected raw coal is also gradually increased. Currently, the coal separation methods commonly used in the coal separation process include dense media, jigging, and flotation. In actual production, the processes of gravity separation, flotation, dehydration, desliming and the like are carried out, and clean coal and coarse coal are lost.

Because the coal slime is very vulnerable to lose coarse coal and clean coal in the flotation process, generally adopt coarse coal slime sorter to carry out coarse coal slime to select separately, coarse coal slime sorter produces two kinds of products: one is clean coal, has low ash content and high value, and is a main product of a coal preparation plant; one is a tailing product, has high ash content and low value, and is a byproduct of a coal preparation plant.

The conventional coarse coal slime separation equipment can only separate clean coal and tailings products, and cannot separate coarse coal, so that a process for recycling coarse coal and clean coal from coal slime is required to be researched, and the yield of the coarse clean coal is expected to be improved.

Disclosure of Invention

The embodiment of the invention provides a system and a method for recovering clean coal from coarse coal slime.

In order to achieve the above purpose, the embodiment of the invention adopts the following technical scheme:

on the one hand, provide a clean coal system is retrieved to coarse coal mud, including coarse coal mud passageway, dehydration unit, transfer passage, screening unit and clean coal passageway, wherein:

the mud inlet end of the dewatering unit is communicated with the coarse coal slime channel, and the mud outlet end of the dewatering unit is communicated with the conveying channel;

the mud inlet end of the screening unit is communicated with the conveying channel, and the mud outlet end of the screening unit is communicated with the clean coal channel;

coarse coal slime passes through the coarse coal slime passageway gets into the dehydration unit, the high-speed rotation of dehydration unit becomes the dehydration coal slime with coarse coal slime dehydration, and the dehydration coal slime passes through transfer passage gets into the screening unit, the high-speed rotation of screening unit sieves out the cleaned coal from the dehydration coal slime, and the cleaned coal passes through cleaned coal passageway output coarse coal slime retrieves the cleaned coal system.

In combination with one aspect, in some embodiments, the dewatering unit includes N drums, and an annular communication channel is provided between adjacent drums, and the annular communication channel conveys coarse coal slime in a previous drum to a next drum for further dewatering treatment; the peripheral wall of the cylinder is provided with a plurality of water filtering holes, and the aperture of each water filtering hole is smaller than 0.3mm;

the screening unit comprises M screening barrels, a spiral communication channel is arranged between every two adjacent screening barrels, and the spiral communication channel conveys the dehydrated coal slime in the previous stage of screening barrels to the next stage of screening barrels for continuous screening treatment; m is more than or equal to N and more than or equal to 2; the screening cylinder is provided with a plurality of screening holes, and the aperture of each screening hole is 2.5mm to 3mm;

the cylinder and the screening cylinder are communicated through the conveying channel.

In combination with one aspect, in some embodiments, the cylinder and the sizing drum are nested with one another, the conveying path being at least N;

the conveying channel is located in the cylinder and the nesting area between the screening cylinders, and coarse slime in the cylinder is dehydrated and then enters the screening cylinders to screen clean coal.

In a combination aspect, in some embodiments, the N cylinders are divided into first to nth stages, the M sizing cylinders are divided into first to mth stages, M > N;

the first N grades the drum and the first N grades the screening barrels are nested with each other in sequence, and the (N + 1) th grade to the M grade the screening barrels screen clean coal in dehydrated coal slime in sequence.

In combination with one aspect, in some embodiments, the transport channels are M;

the first-stage cylinder is communicated with the coarse coal slime channel, the cylinder and the screening cylinder at the same stage are respectively communicated with one conveying channel, the (N + 1) th-Mth-stage screening cylinders are also respectively communicated with one conveying channel, and each stage of screening cylinder is communicated with the clean coal channel;

the coarse coal slime enters a first-stage cylinder through the coarse coal slime channel, and the first-stage cylinder rotates at a high speed to throw out partial moisture in the coarse coal slime through a water filtering hole so as to realize primary dehydration treatment of the coarse coal slime into primary dehydrated coal slime; the first-stage dehydrated coal slime enters a first-stage screening barrel through a first conveying channel, the first-stage screening barrel rotates at a high speed to throw out coal slime of first-stage screened clean coal in the first-stage dehydrated coal slime through screening holes, first-stage screened clean coal is left in the first-stage screening barrel, and the first-stage screened clean coal enters a second-stage screening barrel through a spiral communicating channel; the coal slime of the primary screened clean coal enters a nesting area between the primary screening cylinder and the primary cylinder, and the coal slime of the primary screened clean coal enters the secondary cylinder through an annular communicating channel;

2.5mm to 3mm of clean coal is left after the first-stage screened clean coal is continuously thrown out of the coal slurry through a screening hole in a second-stage screening cylinder rotating at a high speed, and the 2.5mm to 3mm of clean coal is conveyed to an N + 1-stage screening cylinder through the clean coal channel;

the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second-stage dehydrated coal slime enters a second-stage screening barrel through a second conveying channel, the second-stage screening barrel rotates at a high speed to throw out coal slime of second-stage screened clean coal in the second-stage dehydrated coal slime through screening holes, second-stage screened clean coal is left in the second-stage screening barrel, and the second-stage screened clean coal enters a third-stage screening barrel through a spiral communication channel; the coal slime of the second-stage screened clean coal enters a nesting area between a second-stage screening barrel and a second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communication channel;

and so on;

the method comprises the following steps that (1) grade N-1 screened clean coal is continuously thrown out of coal slime through a screening hole in an grade N screening cylinder rotating at a high speed, and then 2.5mm to 3mm clean coal is left, and the 2.5mm to 3mm clean coal is conveyed to the grade N +1 screening cylinder through a clean coal channel;

the Nth-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the N-1-stage screened clean coal through the water filtering holes so as to realize N-stage dehydration treatment of the coal slime of the N-1-stage screened clean coal into N-stage dehydrated coal slime; the N-grade dehydrated coal slime enters an Nth-grade screening barrel through an Nth conveying channel, the Nth-grade screening barrel rotates at a high speed to throw out coal slime of N-grade screened clean coal in the N-grade dehydrated coal slime through screening holes, N-grade screened clean coal is left in the Nth-grade screening barrel, and the N-grade screened clean coal enters an N + 1-grade screening barrel through a spiral communicating channel and an N +1 th conveying channel; coal slime of the N-level screened clean coal enters a nesting area between an Nth-level screening cylinder and an Nth-level cylinder, and a coarse coal slime recovery clean coal system is discharged from the nesting area between the Nth-level screening cylinder and the Nth-level cylinder;

the N + 1-stage screening cylinder rotates at a high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through a screening hole, N + 1-stage screening clean coal is left in the N + 1-stage screening cylinder, and the N + 1-stage screening clean coal enters the N + 2-stage screening cylinder through a spiral communication channel and an N +2 conveying channel;

and so on;

and the M-level screening cylinder rotates at a high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through the screening holes, M-level screening clean coal is left in the M-level screening cylinder, and the M-level screening clean coal passes through the clean coal channel to output coarse coal slime to recover the clean coal system.

In combination with one aspect, in some embodiments, the transport channels are N;

the first-stage cylinder is communicated with the coarse coal slime channel, the cylinders and the screening cylinders of the same stage are respectively communicated with one conveying channel, the Nth-Mth screening cylinders are communicated through the clean coal channel, and each stage of screening cylinder is communicated with the clean coal channel;

the coarse coal slime enters a first-stage cylinder through the coarse coal slime channel, and the first-stage cylinder rotates at a high speed to throw out partial moisture in the coarse coal slime through a water filtering hole so as to realize primary dehydration treatment of the coarse coal slime into primary dehydrated coal slime; the first-stage dehydrated coal slime enters a first-stage screening barrel through a first conveying channel, the first-stage screening barrel rotates at a high speed to throw out coal slime of first-stage screened clean coal in the first-stage dehydrated coal slime through screening holes, first-stage screened clean coal is left in the first-stage screening barrel, and the first-stage screened clean coal enters a second-stage screening barrel through a spiral communicating channel; the coal slime of the primary screened clean coal enters a nesting area between a primary screening barrel and a primary cylinder, and the coal slime of the primary screened clean coal enters a secondary cylinder through an annular communicating channel;

the first-stage screening clean coal is continuously thrown out of coal slime through a screening hole in a second-stage screening cylinder rotating at a high speed, and then 2.5mm to 3mm clean coal is left, and the 2.5mm to 3mm clean coal is conveyed to an N + 1-stage screening cylinder through the clean coal channel;

the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second-stage dehydrated coal slime enters a second-stage screening barrel through a second conveying channel, the second-stage screening barrel rotates at a high speed to throw out coal slime of second-stage screened clean coal in the second-stage dehydrated coal slime through screening holes, second-stage screened clean coal is left in the second-stage screening barrel, and the second-stage screened clean coal enters a third-stage screening barrel through a spiral communication channel; the coal slime of the second-stage screened clean coal enters a nesting area between the second-stage screening cylinder and the second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communicating channel;

and so on;

2.5mm to 3mm of clean coal is left after the N-1 grade screened clean coal is continuously thrown out of the coal slurry through a screening hole in an N-grade screening cylinder rotating at a high speed, and the 2.5mm to 3mm of clean coal is conveyed to an N +1 grade screening cylinder through the clean coal channel;

the N-level cylinder rotates at a high speed to throw out partial moisture of the coal slime of the N-1-level screened clean coal through the water filtering holes so as to realize N-level dehydration treatment of the coal slime of the N-1-level screened clean coal into N-level dehydrated coal slime; the N-grade dehydrated coal slime enters an Nth-grade screening barrel through an Nth conveying channel, the Nth-grade screening barrel rotates at a high speed to throw out coal slime of N-grade screened clean coal in the N-grade dehydrated coal slime through screening holes, N-grade screened clean coal is left in the Nth-grade screening barrel, and the N-grade screened clean coal enters an N + 1-grade screening barrel through the clean coal channel; coal slime of the N-level screened clean coal enters a nesting area between an Nth-level screening cylinder and an Nth-level cylinder, and a coarse coal slime recovery clean coal system is discharged from the nesting area between the Nth-level screening cylinder and the Nth-level cylinder;

the N + 1-stage screening cylinder rotates at a high speed to throw out coal slime mixed in clean coal of 2.5mm to 3mm through a screening hole, N + 1-stage screening clean coal remains in the N + 1-stage screening cylinder, and the N + 1-stage screening clean coal enters the N + 2-stage screening cylinder through the clean coal channel;

and so on;

In combination with one aspect, in some embodiments, each sizing cylinder has a dispersion therein, the dispersion being formulated from water and a dispersant;

the dispersion liquid is mixed with the coal slime to promote the uniform dispersion of particles with different grain diameters in the coal slime.

In another aspect, a clean coal recovery method from coarse coal slime is provided, which includes:

the coarse coal slime is dehydrated into dehydrated coal slime through high-speed rotation of a dehydration unit;

the dehydrated coal slime enters a screening unit to be mixed with the dispersion liquid, so that particles with different particle sizes in the dehydrated coal slime are uniformly dispersed;

the dehydrated coal slime with uniformly dispersed particles is subjected to high-speed rotary screening by a screening unit to obtain clean coal;

clean coal passes through clean coal passageway output coarse coal mud retrieves clean coal system.

In combination with another aspect, in some embodiments, the coarse coal slurry is sequentially dewatered by cylinders of the dewatering unit;

the dehydrated coal slime enters each stage of screening barrel of the screening unit and is respectively mixed with the dispersion liquid of each corresponding stage of screening barrel;

the dehydrated coal slime with uniformly dispersed particles is sequentially screened out clean coal through each stage of screening barrels of the screening unit;

and the dehydrated coal slime dehydrated by the upper-stage cylinder enters the screening cylinder corresponding to the cylinder of the current stage to screen clean coal, the screening cylinder corresponding to the cylinder of the current stage throws the coal slime except the clean coal to a nesting area between the cylinder and the screening cylinder, and the annular communication channel corresponding to the upper-stage cylinder conveys the coal slime in the nesting area to the lower-stage cylinder for continuous dehydration treatment.

In combination with another aspect, in some embodiments, the coarse coal slurry recovery cleaned coal includes state one to state M;

the first state: coarse coal slime enters a first-stage cylinder through a coarse coal slime channel, the first-stage cylinder rotates at a high speed and throws out partial water in the coarse coal slime through a water filtering hole so as to realize primary dehydration treatment of the coarse coal slime into primary dehydrated coal slime; the first-stage dehydrated coal slime enters a first-stage sieving barrel through a first conveying channel, the dehydrated coal slime is mixed with dispersion liquid in the first-stage sieving barrel to form first-stage dehydrated coal slime with uniformly dispersed particles, the first-stage sieving barrel rotates at a high speed to throw out the coal slime of first-stage sieved clean coal in the first-stage dehydrated coal slime with uniformly dispersed particles through a sieving hole, the first-stage sieved clean coal is left in the first-stage sieving barrel, and other cylinders and other sieving barrels pause to work when the first-stage cylinder and the first-stage sieving barrel work;

and a second state: the first-stage cylinder and the first-stage screening cylinder continuously maintain the first state to work, coal slime of first-stage screened clean coal enters a nesting area between the first-stage screening cylinder and the first-stage cylinder, the coal slime of the first-stage screened clean coal enters the second-stage cylinder through an annular communication channel, the first-stage screened clean coal is left behind 2.5mm to 3mm after the coal slime is continuously thrown out of the second-stage screening cylinder rotating at a high speed through a screening hole, and the 2.5mm to 3mm clean coal is conveyed to the (N + 1) th-stage screening cylinder through the clean coal channel; the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second-stage dehydrated coal slime enters a second-stage screening barrel through a second conveying channel, the dehydrated coal slime is mixed with dispersion liquid in the second-stage screening barrel to form second-stage dehydrated coal slime with uniformly dispersed particles, the second-stage screening barrel rotates at a high speed to throw out the coal slime with the uniformly dispersed particles of the second-stage dehydrated coal slime through screening holes, second-stage screened clean coal is left in the second-stage screening barrel, and other cylinders and other screening barrels pause to work when the first-stage cylinder, the first-stage screening barrel, the second-stage cylinder and the second-stage screening barrel work;

and a third state: the first-stage cylinder, the first-stage screening cylinder, the second-stage cylinder and the second-stage screening cylinder continuously maintain the first state and the second state to work, and the second-stage screened clean coal enters the third-stage screening cylinder through the spiral communication channel; the coal slime of the second-stage screened clean coal enters a nesting area between the second-stage screening cylinder and the second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communicating channel; 2.5mm to 3mm of clean coal is left after the first-stage screened clean coal is continuously thrown out of the coal slurry through a screening hole in a second-stage screening cylinder rotating at a high speed, and the 2.5mm to 3mm of clean coal is conveyed to a third-stage screening cylinder through the clean coal channel; the third-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the second-stage screened clean coal through the water filtering holes so as to realize three-stage dehydration treatment of the coal slime of the second-stage screened clean coal into three-stage dehydrated coal slime; the third-stage dehydrated coal slime enters a third-stage screening barrel through a third conveying channel, the third-stage dehydrated coal slime and dispersion liquid in the third-stage screening barrel are mixed into the third-stage dehydrated coal slime with uniformly dispersed particles, the third-stage screening barrel rotates at a high speed to throw out the coal slime with the uniformly dispersed particles of the third-stage dehydrated coal slime through screening holes, the third-stage screening barrel is left with the third-stage screened clean coal, and other cylinders and other screening barrels suspend working when the first-stage cylinder, the first-stage screening barrel, the second-stage cylinder, the second-stage screening barrel, the third-stage cylinder and the third-stage screening barrel work;

the state four, the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage cylinder and the third-stage screening cylinder continuously maintain the state one to the state three for working, the working condition of the fourth-stage cylinder is the same as that of the second-stage cylinder and the third-stage cylinder, and the working condition of the fourth-stage screening cylinder is the same as that of the second-stage screening cylinder and the third-stage screening cylinder; when the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder and the fourth-stage screening cylinder work, other cylinders and other screening cylinders stop working;

the state N, the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder and the fourth-stage screening cylinder continuously maintain the state from one to four, the working condition of the … … N-stage cylinder is the same as that of the second-stage cylinder to the fourth-stage cylinder, and the working condition of the N-stage screening cylinder is the same as that of the second-stage cylinder to the fourth-stage screening cylinder; when the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage screening cylinder, the Nth-stage cylinder and the Nth-stage screening cylinder work, the (N + 1) th-Mth-stage screening cylinders pause to work;

state N +1: the coal slime mixed with 2.5mm to 3mm clean coal is thrown out through a screening hole by the high-speed rotation of the (N + 1) th-stage screening cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder, the … … Nth-stage cylinder and the Nth-stage screening cylinder suspend working from the (N + 2) th-stage to the Mth-stage screening cylinders when the (N + 1) th-stage screening cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder, the … … Nth-stage cylinder, the Nth-stage screening cylinder and the (N + 1) th-stage screening cylinder work;

and a state M: the M-1 grade screened clean coal enters an M grade screening cylinder through a spiral communication channel and a clean coal channel, the M grade screening cylinder rotates at a high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through screening holes, and M grade screened clean coal left in the M grade screening cylinder outputs coarse coal slime through the clean coal channel to a clean coal recovery system; the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage screening cylinder, … … Nth-stage cylinder, nth-stage screening cylinder, N + 1-stage screening cylinder … … Mth-stage screening cylinder continuously maintains the state from one to M until all the screening cylinders and all the cylinders stop working after all the coarse coal slime is recovered and the clean coal is finished.

In the present disclosure, at least the following technical effects or advantages are provided:

in the embodiment of the invention, the coarse coal slime is dehydrated by the dehydration unit and then screened by the screening unit, so that the coarse coal slime generated in the desliming link is used as a raw material to recover clean coal, and the yield of the clean coal is improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments of the present invention or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic block diagram of a coarse coal slurry clean coal recovery system provided in accordance with some embodiments of the present disclosure;

FIG. 2 is a schematic illustration of recovered clean coal of a first coarse coal slurry recovery clean coal system provided in accordance with some embodiments of the present disclosure;

FIG. 3 is a schematic illustration of a second coarse coal slurry recovery clean coal system for recovering clean coal provided in accordance with some embodiments of the present disclosure;

fig. 4 is a flow chart of a coarse coal slurry clean coal recovery method provided in accordance with some embodiments of the present disclosure.

Detailed Description

The present disclosure is described in detail with reference to the embodiments shown in the drawings, but it should be understood that these embodiments are not intended to limit the present disclosure, and those skilled in the art should understand that the functional, methodological, or structural equivalents of these embodiments or substitutions may be included in the scope of the present disclosure.

The coarse coal slime of the embodiment of the disclosure refers to coal slime with granularity close to that of coal slime, generally 0.5-3 mm, and the conventional coarse coal slime recovered clean coal slime is selected for separation or flotation. For sorting, (1) because the ascending material naturally flows out of the overflow weir, the material particles are slightly heavier than water and are difficult to discharge, so that the overflowed water content is high, the solid content is low, and the sorting effect is not ideal; (2) increasing coarse slime to directly influence the recovery rate of the medium; the coarse slime separation efficiency is lower. In addition, the main means for sorting coarse coal slime at present are an aqueous medium swirler, a jigger and the like, the number efficiency of the aqueous medium swirler is generally 87% -95%, and the Ep value is 0.08% -0.12; the separation efficiency of the coarse slime is low, about 50%, and the ash content is reduced, generally only 1% -2%. For flotation, a large amount of coarse slime enters flotation, so that the problem of insufficient flotation capacity is more prominent. The size fraction of the selected materials is widened, so that the dosing system is complicated. In some coal preparation plants, chemicals are added in an ore pulp preparer at one time, so that the ash content of clean coal is inevitably improved; if the sectional dosing is adopted, the medicament is not fully contacted with the coal slurry, so that the medicament consumption is increased, and the effect is not ideal.

In addition, before the slime water enters the flotation, coarse slime is separated out by a grading cyclone in most coal preparation plants, and then the coarse slime is mostly treated after being dehydrated by a coarse slime sieve, but the effect is not good. If the coarse slime sieve is not separately arranged, the classification cyclone underflow before flotation is directly driven into the dense medium cyclone. Apparently, coarse coal slime separation equipment and dewatering equipment are omitted, so that coarse coal slime can enter a dense medium cyclone for fine separation and recovery. In fact, the separation effect of the large-diameter cyclone on coarse coal slime is poor, the coarse coal slime after being refined is incompletely recycled, the coarse coal slime is repeatedly separated and dehydrated in the whole system, and the medium removal effect is seriously influenced.

In addition, the coarse slime is recovered and cleaned coal is concentrated by a cyclone. Although the high-frequency sieve and the coal slime centrifuge only desliming the materials and do not play a role in sorting in principle, the high-frequency sieve and the coal slime centrifuge can reduce the ash content of coarse coal slime to different degrees through the feeding and discharging sieving tests of the high-frequency sieve and the coal slime centrifuge. The concentrated cyclone is conventionally a three-stage cyclone separator, a distributor and a jigging laminated sieve, coal slime containing clean coal is firstly pumped into the three-stage cyclone separator by a pump, and after jigging ash reduction and drying of the jigging laminated sieve, the ash content of the clean coal is reduced to below 10 percent, so that clean coal recovery is realized.

In order to improve the yield of clean coal in the coarse coal, the embodiment of the disclosure develops a system and a method for recycling clean coal again from coal slime, so as to improve the yield of the coarse clean coal.

Referring to fig. 1, an embodiment of the present disclosure provides a coarse coal slurry recovery clean coal system, including a coarse coal slurry channel, a dewatering unit, a conveying channel, a screening unit, and a clean coal channel, wherein: the mud inlet end of the dehydration unit is communicated with the coarse coal slime channel, and the mud outlet end of the dehydration unit is communicated with the conveying channel; the mud inlet end of the screening unit is communicated with the conveying channel, and the mud outlet end of the screening unit is communicated with the clean coal channel; coarse coal slime enters a dehydration unit through a coarse coal slime channel, the dehydration unit rotates at a high speed to dehydrate the coarse coal slime into dehydrated coal slime, the dehydrated coal slime enters a screening unit through a conveying channel, the screening unit rotates at a high speed to screen clean coal from the dehydrated coal slime, and the clean coal is output from the coarse coal slime through a clean coal channel to recover a clean coal system.

The dewatering unit is communicated with the coarse slime channel and comprises N cylinders, an annular communicating channel is arranged between every two adjacent cylinders, the screening unit is communicated with the conveying channel and comprises M screening cylinders, and a screening channel is arranged between every two adjacent screening cylinders; a connecting channel is arranged at the joint of the dewatering unit and the screening unit, the coarse coal slime channel is communicated with the conveying channel through the connecting channel, the cylinder and the screening cylinder are mutually nested, and the cylinder and the screening cylinder are mutually nested; the dehydration unit and the screening unit are both hollow structures.

The dehydration unit and the screening unit are made of water permeable materials. The permeable material is distributed with permeable holes. When the screening unit rotates at a high speed, the cylinder and the screening cylinder are mutually pushed, meanwhile, water between the cylinder and the screening cylinder is thrown out under the action of centrifugal force, and the thrown water is pushed to the outer side of the cylinder by the cylinder and the screening cylinder; under the action of centrifugal force, coal slime except clean coal in the hollow structure screening unit is thrown to a position between the cylinder and the screening cylinder, moisture contained in the clean coal in the screening cylinder is thrown to the hollow structures of the dewatering unit and the screening unit through water permeable holes of water permeable materials, and the moisture thrown to a position between the dewatering unit and the screening unit is pushed to the outer side of the cylinder.

When the screening unit operates at a high speed, negative pressure is generated in the center of the screening unit, and water and coal slime are thrown out to leave only clean coal; meanwhile, as the disc body of the screening cylinder is made of a water-permeable material, water mixed in clean coal is directly thrown out through the water-permeable holes in the disc body, the coal particles in the screening cylinder are further dispersed by the screening unit and the dewatering unit through the pushing action of at least one pair of teeth and the water and the disc body due to the pushing action, and high pressure is generated around the pushing teeth far away from the center of the screening cylinder or the cylinder due to high-speed operation and the disc body, so that the coal particles in the screening cylinder are dispersed.

Referring to fig. 2 and 3, preferably, the dewatering unit comprises N drums, and an annular communication channel is arranged between adjacent drums, and the annular communication channel conveys coarse coal slime in a drum at an upper stage to a drum at a lower stage for further dewatering treatment; the peripheral wall of the cylinder is provided with a plurality of water filtering holes, and the aperture of each water filtering hole is smaller than 0.3mm; referring to fig. 2 and 3, preferably, the screening unit includes M screening drums, and a spiral communication channel is provided between adjacent screening drums, and the spiral communication channel conveys the dewatered coal slime in the previous screening drum to the next screening drum for further screening treatment; m is more than or equal to N and more than or equal to 2; the screening cylinder is provided with a plurality of screening holes, and the aperture of each screening hole is 2.5mm to 3mm; the cylinder and the screening cylinder are communicated through a conveying passage.

In order to improve the recovery rate of clean coal, the cylinder and the screening cylinder of the embodiment of the disclosure are nested with each other, please refer to fig. 2 and fig. 3, and the number of the conveying channels is at least N; the conveying channel is positioned in a nesting area between the cylinder and the screening cylinder, and coarse slime in the cylinder enters the screening cylinder through the conveying channel after dehydration treatment to screen clean coal.

Referring to fig. 2 and 3, N cylinders of the embodiment of the disclosure are divided into first to nth stages, M sieving cylinders are divided into first to mth stages, and M > N; the front N-stage cylinder and the front N-stage screening cylinder are sequentially nested with each other, and the (N + 1) th-Mth-stage screening cylinder sequentially screens clean coal in the dehydrated coal slime.

Referring to fig. 3, the number of the conveying channels in the embodiment of the present disclosure is M; the first-stage cylinder is communicated with the coarse coal slime channel, the cylinder and the screening cylinder at the same stage are respectively communicated with a conveying channel, the (N + 1) th to M-th screening cylinders are respectively communicated with a conveying channel, and each stage of screening cylinder is communicated with the clean coal channel; the coarse coal slime enters a first-stage cylinder through a coarse coal slime channel, and the first-stage cylinder rotates at a high speed to throw out partial moisture in the coarse coal slime through a water filtering hole so as to realize primary dehydration treatment of the coarse coal slime into primary dehydrated coal slime; the first-stage dehydrated coal slime enters a first-stage screening barrel through a first conveying channel, the first-stage screening barrel rotates at a high speed to throw out coal slime of first-stage screened clean coal in the first-stage dehydrated coal slime through screening holes, first-stage screened clean coal is left in the first-stage screening barrel, and the first-stage screened clean coal enters a second-stage screening barrel through a spiral communicating channel; the coal slime of the primary screened clean coal enters a nesting area between a primary screening barrel and a primary cylinder, and the coal slime of the primary screened clean coal enters a secondary cylinder through an annular communicating channel; 2.5mm to 3mm of clean coal is left after the first-stage screened clean coal is continuously thrown out of the coal slurry through a screening hole in a second-stage screening cylinder rotating at a high speed, and the 2.5mm to 3mm of clean coal is conveyed to an N + 1-stage screening cylinder through a clean coal channel; the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second-stage dehydrated coal slime enters a second-stage screening barrel through a second conveying channel, the second-stage screening barrel rotates at a high speed to throw out coal slime of second-stage screened clean coal in the second-stage dehydrated coal slime through screening holes, second-stage screened clean coal is left in the second-stage screening barrel, and the second-stage screened clean coal enters a third-stage screening barrel through a spiral communication channel; the coal slime of the second-stage screened clean coal enters a nesting area between the second-stage screening cylinder and the second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communicating channel; and so on; 2.5mm to 3mm of clean coal is left after the N-1 grade screened clean coal is continuously thrown out of the coal slurry through a screening hole in an N-grade screening cylinder rotating at a high speed, and the 2.5mm to 3mm of clean coal is conveyed to an N +1 grade screening cylinder through a clean coal channel; the N-level cylinder rotates at a high speed to throw out partial moisture of the coal slime of the N-1-level screened clean coal through the water filtering holes so as to realize N-level dehydration treatment of the coal slime of the N-1-level screened clean coal into N-level dehydrated coal slime; the N-level dehydrated coal slime enters an N-level screening barrel through an N-level conveying channel, the N-level screening barrel rotates at a high speed to throw out coal slime of N-level screened clean coal in the N-level dehydrated coal slime through screening holes, N-level screened clean coal is left in the N-level screening barrel, and the N-level screened clean coal enters an N + 1-level screening barrel through a spiral communicating channel and an N + 1-level conveying channel; coal slime of the N-level screened clean coal enters a nesting area between an Nth-level screening cylinder and an Nth-level cylinder, and a coarse coal slime recovery clean coal system is discharged from the nesting area between the Nth-level screening cylinder and the Nth-level cylinder; the N + 1-stage screening cylinder rotates at a high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through a screening hole, N + 1-stage screening clean coal remains in the N + 1-stage screening cylinder, and the N + 1-stage screening clean coal enters the N + 2-stage screening cylinder through a spiral communication channel and an N +2 conveying channel; and so on; and (3) throwing out coal slime mixed in 2.5mm to 3mm clean coal through the screening holes by the high-speed rotation of the M-level screening cylinder, leaving M-level screening clean coal in the M-level screening cylinder, and outputting coarse coal slime to a clean coal recovery system by the M-level screening clean coal through a clean coal channel.

Referring to fig. 2, N conveying channels are provided according to the embodiment of the disclosure; the first-stage cylinder is communicated with the coarse coal slime channel, the cylinders and the screening cylinders of the same stage are respectively communicated with a conveying channel, the Nth-Mth screening cylinders are communicated through the clean coal channel, and each stage of screening cylinder is communicated with the clean coal channel; the coarse coal slime enters a first-stage cylinder through a coarse coal slime channel, and the first-stage cylinder rotates at a high speed to throw out partial moisture in the coarse coal slime through a water filtering hole so as to realize primary dehydration treatment of the coarse coal slime into primary dehydrated coal slime; the first-stage dehydrated coal slime enters a first-stage screening barrel through a first conveying channel, the first-stage screening barrel rotates at a high speed to throw out coal slime of first-stage screened clean coal in the first-stage dehydrated coal slime through screening holes, first-stage screened clean coal is left in the first-stage screening barrel, and the first-stage screened clean coal enters a second-stage screening barrel through a spiral communicating channel; the coal slime of the primary screened clean coal enters a nesting area between the primary screening cylinder and the primary cylinder, and the coal slime of the primary screened clean coal enters the secondary cylinder through an annular communicating channel; 2.5mm to 3mm of clean coal is left after the first-stage screened clean coal is continuously thrown out of the coal slurry through a screening hole in a second-stage screening cylinder rotating at a high speed, and the 2.5mm to 3mm of clean coal is conveyed to an N + 1-stage screening cylinder through a clean coal channel; the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second-stage dehydrated coal slime enters a second-stage screening barrel through a second conveying channel, the second-stage screening barrel rotates at a high speed to throw out coal slime of second-stage screened clean coal in the second-stage dehydrated coal slime through screening holes, second-stage screened clean coal is left in the second-stage screening barrel, and the second-stage screened clean coal enters a third-stage screening barrel through a spiral communication channel; the coal slime of the second-stage screened clean coal enters a nesting area between a second-stage screening barrel and a second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communication channel; and so on; 2.5mm to 3mm of clean coal is left after the N-1 grade screened clean coal is continuously thrown out of the coal slurry through a screening hole in an N-grade screening cylinder rotating at a high speed, and the 2.5mm to 3mm of clean coal is conveyed to an N +1 grade screening cylinder through a clean coal channel; the N-level cylinder rotates at a high speed to throw out partial moisture of the coal slime of the N-1-level screened clean coal through the water filtering holes so as to realize N-level dehydration treatment of the coal slime of the N-1-level screened clean coal into N-level dehydrated coal slime; the N-grade dehydrated coal slime enters an Nth-grade screening barrel through an Nth conveying channel, the Nth-grade screening barrel rotates at a high speed to throw out coal slime of N-grade screened clean coal in the N-grade dehydrated coal slime through screening holes, N-grade screened clean coal is left in the Nth-grade screening barrel, and the N-grade screened clean coal enters an N + 1-grade screening barrel through a clean coal channel; coal slime of the N-level screened clean coal enters a nesting area between an Nth-level screening cylinder and an Nth-level cylinder, and a coarse coal slime recovery clean coal system is discharged from the nesting area between the Nth-level screening cylinder and the Nth-level cylinder; the N + 1-stage screening cylinder rotates at a high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through a screening hole, N + 1-stage screening clean coal is left in the N + 1-stage screening cylinder, and the N + 1-stage screening clean coal enters the N + 2-stage screening cylinder through a clean coal channel; and so on; and (3) throwing out coal slime mixed in 2.5mm to 3mm clean coal through the screening holes by the high-speed rotation of the M-level screening cylinder, leaving M-level screening clean coal in the M-level screening cylinder, and outputting coarse coal slime to a clean coal recovery system by the M-level screening clean coal through a clean coal channel.

In order to further improve the recovery rate of clean coal, dispersion liquid is arranged in each stage of screening cylinder in the embodiment of the disclosure, and the dispersion liquid is prepared by mixing water and a dispersing agent; the dispersion liquid is mixed with the coal slime to promote the uniform dispersion of particles with different grain diameters in the coal slime. The dispersion liquid disclosed by the embodiment of the disclosure can promote coal particles to be uniformly dispersed in water and promote particles with different particle sizes in coal slime to be uniformly dispersed.

Referring to fig. 4, an embodiment of the present disclosure further provides a method for recovering clean coal from coarse coal slime, including: the coarse coal slime is dehydrated into dehydrated coal slime through high-speed rotation of a dehydration unit; the dehydrated coal slime enters a screening unit to be mixed with the dispersion liquid, so that particles with different particle sizes in the dehydrated coal slime are uniformly dispersed; the dehydrated coal slime with uniformly dispersed particles is subjected to high-speed rotary screening by a screening unit to obtain clean coal; the clean coal is output to the coarse coal slime through the clean coal channel to recover the clean coal system.

On the basis of the method shown in fig. 4, the coarse coal slime of the embodiment of the disclosure is sequentially dehydrated through cylinders of various levels of the dehydration unit; the dehydrated coal slime enters each stage of screening barrel of the screening unit and is respectively mixed with the dispersion liquid of each corresponding stage of screening barrel; the dehydrated coal slime with uniformly dispersed particles is sequentially screened out clean coal through each stage of screening barrels of the screening unit; and the dehydrated coal slime dehydrated by the upper-stage cylinder enters the screening cylinder corresponding to the cylinder of the current stage to screen clean coal, the screening cylinder corresponding to the cylinder of the current stage throws the coal slime except the clean coal to a nesting area between the cylinder and the screening cylinder, and the annular communication channel corresponding to the upper-stage cylinder conveys the coal slime in the nesting area to the lower-stage cylinder for continuous dehydration treatment.

Note that the coarse coal slime recovery clean coal of the embodiment of the present disclosure includes state one to state M; specifically, the method comprises the following steps:

the first state: the coarse coal slime enters a first-stage cylinder through a coarse coal slime channel, and the first-stage cylinder rotates at a high speed to throw out partial moisture in the coarse coal slime through a water filtering hole so as to realize primary dehydration treatment of the coarse coal slime into primary dehydrated coal slime; the one-level dehydrated coal slime gets into first order screening section of thick bamboo through a transfer passage, dehydrated coal slime mixes the one-level dehydrated coal slime of granule homodisperse with the dispersion in the first order screening section of thick bamboo, the high-speed rotation of first order screening section of thick bamboo throws away the coal slime of one-level screening cleaned coal among the one-level dehydrated coal slime of granule homodisperse through the screening hole, leave over one-level screening cleaned coal in the first order screening section of thick bamboo, other drums of first order drum and first order screening section of thick bamboo during operation and other screening section of thick bamboos pause work.

And a second state: the first-stage cylinder and the first-stage screening cylinder continuously maintain the state I to work, coal slime of first-stage screened clean coal enters a nesting area between the first-stage screening cylinder and the first-stage cylinder, the coal slime of the first-stage screened clean coal enters the second-stage cylinder through an annular communication channel, the first-stage screened clean coal is left behind after the coal slime is continuously thrown out of the second-stage screening cylinder rotating at a high speed through a screening hole, and the 2.5mm to 3mm clean coal is conveyed to the (N + 1) th-stage screening cylinder through a clean coal channel; the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second grade dehydrated coal slime enters a second grade screening barrel through a second conveying channel, the dehydrated coal slime is mixed with dispersion liquid in the second grade screening barrel to form the second grade dehydrated coal slime with uniformly dispersed particles, the second grade screening barrel rotates at a high speed to throw away the coal slime with the second grade screened clean coal in the second grade dehydrated coal slime with uniformly dispersed particles through screening holes, the second grade screened clean coal is left in the second grade screening barrel, and the first grade cylinder, the first grade screening barrel, other cylinders and other screening barrels pause during the work of the second grade cylinder and the second grade screening barrel.

And a third state: the first-stage cylinder, the first-stage screening cylinder, the second-stage cylinder and the second-stage screening cylinder continuously maintain the first state and the second state to work, and the second-stage screened clean coal enters the third-stage screening cylinder through the spiral communication channel; the coal slime of the second-stage screened clean coal enters a nesting area between a second-stage screening barrel and a second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communication channel; the first-stage screening clean coal is continuously thrown out of coal slime through a screening hole in a second-stage screening cylinder rotating at a high speed, and then 2.5mm to 3mm clean coal is left, and the 2.5mm to 3mm clean coal is conveyed to a third-stage screening cylinder through a clean coal channel; the third-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the second-stage screened clean coal through the water filtering holes so as to realize three-stage dehydration treatment of the coal slime of the second-stage screened clean coal into three-stage dehydrated coal slime; the tertiary dehydrated coal slime gets into third level screening section of thick bamboo through third transfer passage, tertiary dehydrated coal slime mixes the tertiary dehydrated coal slime of granule homodisperse with the dispersion in the third level screening section of thick bamboo, the tertiary screen section of thick bamboo is high-speed rotatory throws away the coal slime of tertiary screen sizing cleaned coal among the tertiary dehydrated coal slime of granule homodisperse through the screening hole, leave over tertiary screen sizing cleaned coal in the third level screening section of thick bamboo, the first level drum, the first level screening section of thick bamboo, the second level drum, the second level screening section of thick bamboo, other drums of third level drum and the work of third level screening section of thick bamboo during operation and other screens section of thick bamboo pause work.

The state four, the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage cylinder and the third-stage screening cylinder continuously maintain the state one to the state three for working, the working condition of the fourth-stage cylinder is the same as that of the second-stage cylinder and the third-stage cylinder, and the working condition of the fourth-stage screening cylinder is the same as that of the second-stage screening cylinder and the third-stage screening cylinder; when the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder and the fourth-stage screening cylinder work, other cylinders and other screening cylinders pause to work.

The state N, the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder and the fourth-stage screening cylinder continuously maintain the state from one to four for working, the working condition of the … … Nth-stage cylinder is the same as the working condition of the second-stage to fourth-stage cylinders, and the working condition of the Nth-stage screening cylinder is the same as the working condition of the second-stage to fourth-stage screening cylinders; when the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage screening cylinder, the Nth-stage cylinder and the Nth-stage screening cylinder work, the (N + 1) th-M th-stage screening cylinder suspends work.

State N +1: the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage screening cylinder, the … … Nth-stage cylinder and the Nth-stage screening cylinder continuously maintain the state from one to N to work, the (N + 1) th-stage screening cylinder rotates at high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through screening holes, the N +1 grade screening barrel is left with N +1 grade screening clean coal, and the first grade cylinder, the first grade screening barrel, the second grade cylinder, the second grade screening barrel, the third grade cylinder, the third grade screening barrel, the fourth grade cylinder, the fourth grade screening barrel … … N grade cylinder, the N grade screening barrel and the N +1 grade screening barrel are operated, and the N +2 grade to M grade screening barrels pause.

And a state M: the M-1 grade screened clean coal enters an M grade screening cylinder through a spiral communication channel and a clean coal channel, the M grade screening cylinder rotates at a high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through screening holes, and M grade screened clean coal left in the M grade screening cylinder outputs coarse coal slime through a clean coal channel to a clean coal recovery system; the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage screening cylinder, … … Nth-stage cylinder, nth-stage screening cylinder, N + 1-stage screening cylinder … … Mth-stage screening cylinder continuously maintains the state from one to M until all the screening cylinders and all the cylinders stop working after all the coarse coal slime is recovered and the clean coal is finished.

The above-listed detailed description is merely a specific description of possible embodiments of the present disclosure, and is not intended to limit the scope of the disclosure, which is intended to include within its scope equivalent embodiments or modifications that do not depart from the technical spirit of the present disclosure.

It will be evident to those skilled in the art that the disclosure is not limited to the details of the foregoing illustrative embodiments, and that the present disclosure may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the disclosure being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art.

Claims

1. Clean coal system is retrieved to coarse coal mud, its characterized in that, including coarse coal mud passageway, dehydration unit, transfer passage, screening unit and clean coal passageway, wherein:

the mud inlet end of the dehydration unit is communicated with the coarse coal slime channel, and the mud outlet end of the dehydration unit is communicated with the conveying channel;

coarse coal slime enters the dehydration unit through the coarse coal slime channel, the dehydration unit rotates at a high speed to dehydrate the coarse coal slime into dehydrated coal slime, the dehydrated coal slime enters the screening unit through the conveying channel, the screening unit rotates at a high speed to screen clean coal from the dehydrated coal slime, and the clean coal is output to the coarse coal slime recovery clean coal system through the clean coal channel; the number of the conveying channels is N;

the dehydration unit comprises N cylinders, an annular communication channel is arranged between every two adjacent cylinders, a plurality of water filtering holes are formed in the peripheral wall of each cylinder, and the aperture of each water filtering hole is smaller than 0.3mm;

the screening unit comprises M screening cylinders, spiral communication channels are arranged among 1~N grade screening cylinders, a plurality of screening holes are formed in the screening cylinders, the aperture of each screening hole is 2.5mm to 3mm, and M is larger than N and larger than or equal to 2;

the first N-stage cylinder and the first N-stage screening cylinder are mutually nested in sequence, and the (N + 1) th stage to the M-th stage screening cylinder screen clean coal in the dehydrated coal slime in sequence;

the conveying channel is positioned in a nesting area between the cylinder and the screening cylinder, and coarse slime in the cylinder enters the screening cylinder through the conveying channel after dehydration treatment to screen clean coal;

the first-stage cylinder is communicated with the coarse coal slime channel, the cylinders and the screening cylinders of the same stage are respectively communicated with a conveying channel, the Nth-Mth screening cylinders are communicated through the clean coal channel, and each stage of screening cylinder is communicated with the clean coal channel;

the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second-stage dehydrated coal slime enters a second-stage screening barrel through a second conveying channel, the second-stage screening barrel rotates at a high speed to throw out coal slime of second-stage screened clean coal in the second-stage dehydrated coal slime through screening holes, second-stage screened clean coal is left in the second-stage screening barrel, and the second-stage screened clean coal enters a third-stage screening barrel through a spiral communicating channel; the coal slime of the second-stage screened clean coal enters a nesting area between a second-stage screening barrel and a second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communication channel;

and so on;

the N-level cylinder rotates at a high speed to throw out partial moisture of the coal slime of the N-1-level screened clean coal through the water filtering holes so as to realize N-level dehydration treatment of the coal slime of the N-1-level screened clean coal into N-level dehydrated coal slime; the N-level dehydrated coal slime enters an Nth-level screening barrel through an Nth conveying channel, the Nth-level screening barrel rotates at a high speed to throw out coal slime of N-level screened clean coal in the N-level dehydrated coal slime through screening holes, N-level screened clean coal is left in the Nth-level screening barrel, and the N-level screened clean coal enters an N + 1-level screening barrel through the clean coal channel; coal slime of the N-level screened clean coal enters a nesting area between an Nth-level screening cylinder and an Nth-level cylinder, and a coarse coal slime recovery clean coal system is discharged from the nesting area between the Nth-level screening cylinder and the Nth-level cylinder;

and so on;

2. The coarse coal slime recovery and clean coal system of claim 1 wherein each stage of the screen cylinder has a dispersion liquid therein, the dispersion liquid being prepared from water and a dispersant;

3. The coarse coal slime clean coal recovery method is characterized in that the coarse coal slime clean coal recovery method is based on the coarse coal slime clean coal recovery system of claim 1, and the coarse coal slime clean coal recovery method comprises the following steps:

4. The method for recovering clean coal from coarse coal slime according to claim 3, characterized in that the coarse coal slime is sequentially dehydrated through cylinders of each stage of the dehydration unit;

and the dehydrated coal slime dehydrated by the upper-stage cylinder enters the screening cylinder corresponding to the cylinder at the current stage to screen clean coal, the screening cylinder corresponding to the cylinder at the current stage throws the coal slime except the clean coal to a nesting area between the cylinder and the screening cylinder, and the annular communication channel corresponding to the upper-stage cylinder conveys the coal slime in the nesting area to the lower-stage cylinder for continuous dehydration treatment.

5. The coarse coal slime clean coal recovery method of claim 3 or 4, wherein the coarse coal slime clean coal recovery method comprises the steps of state one to state M;

the first state: the coarse coal slime enters a first-stage cylinder through a coarse coal slime channel, and the first-stage cylinder rotates at a high speed to throw out partial moisture in the coarse coal slime through a water filtering hole so as to realize primary dehydration treatment of the coarse coal slime into primary dehydrated coal slime; the first-stage dehydrated coal slime enters a first-stage screening barrel through a first conveying channel, the dehydrated coal slime is mixed with dispersion liquid in the first-stage screening barrel to form first-stage dehydrated coal slime with uniformly dispersed particles, the first-stage screening barrel rotates at a high speed to throw out the coal slime with the uniformly dispersed particles from the first-stage dehydrated coal slime through screening holes, first-stage screened clean coal is left in the first-stage screening barrel, and other cylinders and other screening barrels pause to work when the first-stage cylinder and the first-stage screening barrel work;

and a second state: the first-stage cylinder and the first-stage screening cylinder continuously maintain the state I to work, coal slime of first-stage screened clean coal enters a nesting area between the first-stage screening cylinder and the first-stage cylinder, the coal slime of the first-stage screened clean coal enters the second-stage cylinder through an annular communication channel, the first-stage screened clean coal is left behind after the coal slime is continuously thrown out of the second-stage screening cylinder rotating at a high speed through a screening hole, and the 2.5mm to 3mm clean coal is conveyed to the (N + 1) th-stage screening cylinder through the clean coal channel; the second-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the first-stage screened clean coal through the water filtering holes so as to realize secondary dehydration treatment of the coal slime of the first-stage screened clean coal into secondary dehydrated coal slime; the second-stage dehydrated coal slime enters a second-stage screening barrel through a second conveying channel, the dehydrated coal slime is mixed with dispersion liquid in the second-stage screening barrel to form second-stage dehydrated coal slime with uniformly dispersed particles, the second-stage screening barrel rotates at a high speed to throw out the coal slime with the uniformly dispersed particles of the second-stage dehydrated coal slime through screening holes, second-stage screened clean coal is left in the second-stage screening barrel, and other cylinders and other screening barrels pause to work when the first-stage cylinder, the first-stage screening barrel, the second-stage cylinder and the second-stage screening barrel work;

and a third state: the first-stage cylinder, the first-stage screening cylinder, the second-stage cylinder and the second-stage screening cylinder continuously maintain the first state and the second state to work, and the second-stage screened clean coal enters the third-stage screening cylinder through the spiral communication channel; the coal slime of the second-stage screened clean coal enters a nesting area between the second-stage screening cylinder and the second-stage cylinder, and the coal slime of the second-stage screened clean coal enters a third-stage cylinder through an annular communicating channel; the first-stage screening clean coal is continuously thrown out of coal slime through a screening hole in a second-stage screening cylinder rotating at a high speed, and then 2.5mm to 3mm clean coal is left, and the 2.5mm to 3mm clean coal is conveyed to a third-stage screening cylinder through the clean coal channel; the third-stage cylinder rotates at a high speed to throw out partial moisture of the coal slime of the second-stage screened clean coal through the water filtering holes so as to realize three-stage dehydration treatment of the coal slime of the second-stage screened clean coal into three-stage dehydrated coal slime; the third-stage dehydrated coal slime enters a third-stage screening barrel through a third conveying channel, the third-stage dehydrated coal slime and dispersion liquid in the third-stage screening barrel are mixed into the third-stage dehydrated coal slime with uniformly dispersed particles, the third-stage screening barrel rotates at a high speed to throw out the coal slime with the uniformly dispersed particles of the third-stage dehydrated coal slime through screening holes, the third-stage screening barrel is left with the third-stage screened clean coal, and other cylinders and other screening barrels suspend working when the first-stage cylinder, the first-stage screening barrel, the second-stage cylinder, the second-stage screening barrel, the third-stage cylinder and the third-stage screening barrel work;

the state IV, the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage cylinder and the third-stage screening cylinder continuously maintain the state I to the state III for work, the working condition of the fourth-stage cylinder is the same as that of the second-stage cylinder and the third-stage cylinder, and the working condition of the fourth-stage screening cylinder is the same as that of the second-stage screening cylinder and the third-stage screening cylinder; when the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder and the fourth-stage screening cylinder work, other cylinders and other screening cylinders stop working;

the state N, the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage cylinder and the fourth-stage screening cylinder continuously maintain the state from one to four, the working condition of the … … N-stage cylinder is the same as that of the second-stage cylinder to the fourth-stage cylinder, and the working condition of the N-stage screening cylinder is the same as that of the second-stage cylinder to the fourth-stage screening cylinder; when the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage screening cylinder, the Nth-stage cylinder and the Nth-stage screening cylinder work, the operation of the (N + 1) th-Mth-stage screening cylinder is suspended;

and a state M: the M-1 grade screened clean coal enters an M grade screening cylinder through a spiral communication channel and a clean coal channel, the M grade screening cylinder rotates at a high speed to throw out coal slime mixed in 2.5mm to 3mm clean coal through screening holes, and M grade screened clean coal left in the M grade screening cylinder outputs coarse coal slime through the clean coal channel to a clean coal recovery system; the first-stage cylinder, the first-stage screening cylinder, the second-stage screening cylinder, the third-stage screening cylinder, the fourth-stage screening cylinder, … … Nth-stage cylinder, nth-stage screening cylinder, N + 1-stage screening cylinder … … Mth-stage screening cylinder continuously maintain the state from one to M until all the screening cylinders and all the cylinders stop working after all the coarse coal slime finishes recovering the clean coal.