CN113145292A - Grading and selecting method for multistage screening and powder removal of power coal - Google Patents
Grading and selecting method for multistage screening and powder removal of power coal Download PDFInfo
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- CN113145292A CN113145292A CN202110420363.0A CN202110420363A CN113145292A CN 113145292 A CN113145292 A CN 113145292A CN 202110420363 A CN202110420363 A CN 202110420363A CN 113145292 A CN113145292 A CN 113145292A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B7/00—Combinations of wet processes or apparatus with other processes or apparatus, e.g. for dressing ores or garbage
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03B—SEPARATING SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS
- B03B5/00—Washing granular, powdered or lumpy materials; Wet separating
- B03B5/28—Washing granular, powdered or lumpy materials; Wet separating by sink-float separation
- B03B5/30—Washing granular, powdered or lumpy materials; Wet separating by sink-float separation using heavy liquids or suspensions
- B03B5/36—Devices therefor, other than using centrifugal force
- B03B5/40—Devices therefor, other than using centrifugal force of trough type
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B03—SEPARATION OF SOLID MATERIALS USING LIQUIDS OR USING PNEUMATIC TABLES OR JIGS; MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C—MAGNETIC OR ELECTROSTATIC SEPARATION OF SOLID MATERIALS FROM SOLID MATERIALS OR FLUIDS; SEPARATION BY HIGH-VOLTAGE ELECTRIC FIELDS
- B03C1/00—Magnetic separation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/28—Moving screens not otherwise provided for, e.g. swinging, reciprocating, rocking, tilting or wobbling screens
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B07—SEPARATING SOLIDS FROM SOLIDS; SORTING
- B07B—SEPARATING SOLIDS FROM SOLIDS BY SIEVING, SCREENING, SIFTING OR BY USING GAS CURRENTS; SEPARATING BY OTHER DRY METHODS APPLICABLE TO BULK MATERIAL, e.g. LOOSE ARTICLES FIT TO BE HANDLED LIKE BULK MATERIAL
- B07B1/00—Sieving, screening, sifting, or sorting solid materials using networks, gratings, grids, or the like
- B07B1/46—Constructional details of screens in general; Cleaning or heating of screens
- B07B1/4609—Constructional details of screens in general; Cleaning or heating of screens constructional details of screening surfaces or meshes
Abstract
The invention discloses a grading and selecting method for multistage screening and powder removal of power coal, which comprises the following steps: raw coal is subjected to dry classification of 50mm, 25mm or 13mm through a first rigid-flexible coupling screen surface elastic vibrating screen, materials above a sieve with the size of 50(25/13) mm enter a heavy-medium shallow groove separator for separation, the separated light products and heavy products are subjected to medium removal and dehydration to obtain clean coal and gangue products, and materials below the sieve enter a relaxation screen with the size of 3mm or 2mm for dry classification; feeding the material on the relaxation sieve into a second rigid-flexible coupling elastic sieve surface vibrating sieve with the diameter of 3mm or 2mm for dry powder removal, taking the material under the second rigid-flexible coupling elastic sieve surface vibrating sieve with the diameter of 3mm or 2mm and the material under the relaxation sieve with the diameter of 3mm or 2mm as coal blending products, and dehydrating light and heavy products after the material on the sieve with the diameter of 50(25/13) -3(2) mm is separated by a heavy medium shallow groove separator after medium removal to obtain clean coal and gangue products; the process has the advantages of high raw coal dressing rate, high separation precision and small load of a slime water system, and has obvious effect on treating sticky and wet easily-argillized power coal.
Description
Technical Field
The invention relates to the technical field of coal sorting, in particular to a grading and selecting method for multistage screening and powder removal of power coal.
Background
Coal is the main primary energy in China, is the most economic, reliable and basic guarantee of energy safety and energy strategies in China, and makes great contribution to the national economic development of China. The efficient clean processing and utilization of coal resources is an economic and effective method for reducing the discharge amount of sulfur dioxide, nitrogen oxides and smoke dust, is a premise of deep processing of coal, and is one of key technologies for energy conservation and emission reduction.
At present, the power coal preparation plant mostly adopts raw coal for 13(6) grading, gangue is separated and discharged by a movable sieve jigging or heavy medium shallow slot separator with the diameter of more than 13mm, the gangue is not selected, the process is not selected, the raw coal is low in selection proportion, the clean coal yield is low, and the economic benefit of the coal preparation plant is poor; in order to meet the requirements of users on the quality of coal products, the raw coal entering proportion needs to be improved, and the entering quantity needs to be increased. However, the coal slime brought in the separation process needs to be dehydrated and recovered, the coal slime dehydration effect is poor, the coal slime has high water content and low heat productivity, and some coal preparation plants even have the phenomenon that the heat productivity of the separated product coal is lower than that of the raw coal. In addition, when the coal slime is easy to argillize, excessive coal slime enters the separation system, the coal slime is difficult to settle, and water is difficult to remove, so that the content of the coal slime in circulating water is too high, the separation operation is influenced, and the normal operation of a production process system of a coal preparation plant is influenced.
The patent application CN112371325A discloses a grading and washing process for power coal, raw coal is sieved and separated into raw coal with grain size fractions of more than 25mm, 25-13mm and less than 13mm, all the raw coal with grain size of more than 25mm enters a lump coal dense medium separation system, the separated lump clean coal and lump gangue enter a lump coal dehydration and medium removal system for treatment and are respectively output, and the sieved water enters a slime water treatment system; all raw coal of 25-13mm is directly transferred to a block clean coal belt, raw coal of <13mm is subjected to deep screening and powder removal, wherein raw coal of >6mm is transferred to the block clean coal belt for output, and slack coal of <6mm enters a slack coal bin for output. According to the process, 25/13mm classification is adopted, the slack coal part below 13mm does not enter the separation, the washing rate is not high, and secondly, the process has no slack coal separation system, and the slack coal is only subjected to screening treatment, so that the quality of the separated product is not high.
Disclosure of Invention
The invention provides a grading and selecting method for multistage screening and powder removal of power coal for making up the defects of the prior art, the grading and selecting method adopts 50(25/13)/3(2) mm grading, the washing rate is higher, the lower limit of screening can be 2mm or 3mm, the sorting precision is high, and the grading and selecting method has obvious effect on treating viscous wet easily-argillized power coal.
In order to achieve the purpose, the invention adopts the following technical scheme: a grading and selecting method for multi-stage screening and powder removal of power coal comprises the following steps:
1) raw coal is screened by a first rigid-flexible coupling screen surface elastic vibrating screen and classified by a dry method, so as to obtain a first oversize material with the particle size larger than the size of a screen hole and a first undersize material with the particle size smaller than the size of the screen hole, the first oversize material enters a heavy-medium shallow groove separator for separation, and a light product and a heavy product obtained after separation are subjected to medium removal to respectively obtain clean coal, gangue and a coal slime water medium system; the screen hole size of the first rigid-flexible coupling screen surface elastic vibrating screen is selected from one of 50mm, 25mm and 13 mm;
2) step 1) screening the first undersize material in a relaxation sieve to obtain a second oversize material with the particle size larger than the size of a sieve pore and a second undersize material with the particle size smaller than the size of the sieve pore by dry classification, wherein the sieve pore size of the relaxation sieve is 2mm or 3 mm;
3) step 2) screening the second oversize material by a second rigid-flexible coupling elastic screen surface vibrating screen to remove powder by a dry method, and obtaining a third oversize material with the particle size larger than the size of a screen hole and a third undersize material with the particle size smaller than the size of the screen hole; the materials on the third screen after the powder removal enter a heavy-medium shallow groove separator for separation, and the light products and the heavy products obtained by separation are subjected to medium removal and dehydration to respectively obtain clean coal, gangue and a coal slime water medium system; the size of the sieve pore of the second rigid-flexible coupling elastic sieve surface vibrating sieve is 2mm or 3 mm;
4) taking the third undersize material obtained in the step 3) and the second undersize material obtained in the step 2) as a coal blending product, wherein the particle sizes of the second undersize material and the third undersize material are less than 2mm or 3 mm;
5) step 1) the coal slime aqueous medium system that obtains through taking off the medium to and step 3) the coal slime aqueous medium system that obtains through taking off the medium and dehydration gets into the magnet separator and purifies the recovery, obtain the coal slime water after the magnetic separation, the coal slime water obtains coarse coal mud and fine coal mud through grading, coarse coal mud dehydration is retrieved, fine coal mud is retrieved through concentrated back filter-pressing.
According to the method, in the step 1), a first rigid-flexible coupling elastic screen surface vibrating screen surface adopts a modular casting rigid-flexible coupling elastic screen surface or a rigid-flexible coupling elastic rod screen surface; the screen hole size of the elastic vibrating screen with the first rigid-flexible coupling screen surface is preferably 50mm or 25 mm; correspondingly, if raw coal is subjected to 50mm dry classification (namely the sieve pore size is 50mm) by a rigid-flexible coupling sieve surface elastic vibrating screen, a first oversize material with a size of more than 50mm and a first undersize material with a size of less than 50mm are obtained; if raw coal is subjected to 25mm dry classification by a rigid-flexible coupling screen surface elastic vibrating screen, 25mm first oversize materials and 25mm first undersize materials are obtained.
According to the method of the invention, in the step 2), if the first undersize material enters a relaxation sieve for 3mm dry classification (namely, the sieve pore size is 3mm), a second oversize material with the size of >3mm and a second undersize material with the size of <3mm are obtained; correspondingly, if the first undersize material enters a relaxation sieve for 2mm dry classification, a second oversize material with the size larger than 2mm and a second undersize material with the size smaller than 2mm are obtained.
According to the method of the invention, in the step 3), the second rigid-flexible coupling elastic screen surface vibrating screen surface adopts a modular cast rigid-flexible coupling elastic screen surface or a rigid-flexible coupling elastic rod screen surface, and similar to the previous description, if the second oversize material enters a 3mm second rigid-flexible coupling elastic screen surface vibrating screen for screening to dry-process powder removal, a third oversize material with a size larger than 3mm and a third undersize material with a size smaller than 3mm are obtained.
In a specific embodiment, the heavy product obtained by the heavy medium shallow slot separator in the step 1) is subjected to gangue removal and medium removal through a gangue removal sieve to obtain a gangue product and a coal slime water medium system; and (3) carrying out the dense-medium shallow-slot separator on the light product to obtain a clean coal product and a coal slime water medium system after the clean coal is subjected to medium removal by a clean coal medium removal sieve.
In a specific embodiment, the heavy product obtained by the heavy medium shallow slot separator in the step 3) is subjected to gangue removal and medium removal through a gangue removal sieve to obtain a gangue product and a coal slime water medium system; and (3) carrying out medium removal by a clean coal medium removal sieve and dehydration by a centrifugal dehydrator on the light product of the heavy-medium shallow-slot separator to obtain a clean coal product and a coal slime water medium system.
In a specific embodiment, in the steps 1) and 3), undersize dilute media of the gangue and clean coal medium removing sieves enter the dilute medium barrel, and undersize qualified media of the gangue and clean coal medium removing sieves enter the qualified medium barrel.
In a specific embodiment, in the step 5), the undersize shunt of the gangue and clean coal medium removal sieves, the centrifugate of the centrifugal dehydrator, the undersize dilute medium of the gangue and clean coal medium removal sieves in the steps 1) and 3) enter the dilute medium barrel, the material in the dilute medium barrel enters the magnetic separator for magnetic separation, the magnetic separation concentrate after magnetic separation enters the qualified medium barrel, the magnetic separation tailings enter the coal slime bucket, and then enter the grading cyclone for grading to obtain overflow and underflow.
Preferably, in the step 5), the classifying cyclone is a hydrocyclone.
In a specific embodiment, the underflow classified by the classification cyclone is dehydrated by a coal slime sieve and a coal slime centrifugal machine in sequence to obtain a coarse coal slime product; undersize materials of the coal slime sieve, centrifugal liquid of the coal slime centrifugal machine and overflow of the grading cyclone enter a thickener for concentration and filter pressing.
In specific embodiments, further, the concentration and pressure filtration comprises: the overflow of the thickener is used as clear water and enters a circulating water system for recycling; the underflow of the thickener enters a coal slime mixing barrel, the materials in the barrel enter a filter press, a coal slime product is obtained after filter pressing, and the filtrate of the plate filter press enters a filtrate barrel and then enters the thickener.
Those skilled in the art understand that the devices involved in the method of the present invention are conventional devices in the art, and the specific structure thereof can be known according to the names and functions thereof, and will not be described in detail.
Compared with the prior art, the invention has the following advantages:
1) the method adopts 3mm or 2mm relaxation sieve for classification, then enters a separation system after the powder is removed from the rigid-flexible coupling sieve surface, and adopts a heavy-medium shallow slot separator for separation in the subsequent separation, so that the separation precision is prevented from being influenced by the great increase of the content of secondary coal slime in the separation process; the process of the invention can obviously reduce the content of the coal slime in the system, increase the sorting precision and reduce the load of a coal slime water system, and the grading granularity can be further reduced to 3mm or 2mm, for example.
2) The invention adopts the classification of 50(25/13)/3(2) mm, and the washing rate is higher. And the invention is provided with corresponding devices for desliming and slack coal separation, so that the content of the coal slime in the system is lower, and the separation precision and the product quality are improved.
In conclusion, the grading and selecting process for multistage screening and powder removal of power coal provided by the invention has the advantages that the lower screening limit can be expanded to 3mm or 2mm by adopting the means of relaxation screening dry-method grading and rigid-flexible coupling screen surface dry-method powder removal, so that the raw coal selecting rate is high, the load of a slime water system is small, and the operation cost is low compared with other processes, and the grading and selecting mode is adopted, so that the feeding grain grade of a dense medium system is narrow, and the quantity of system slime is reduced after desliming and screening, so that the sorting precision is high. The invention has the characteristics of stable and efficient production, low energy consumption, low medicine consumption, large treatment capacity and the like, has obvious effect on treating the sticky and wet easily-argillized power coal and has obvious economic benefit.
Drawings
FIG. 1 is a schematic flow chart of a grading and selecting method for multi-stage screening and dust removal of power coal.
FIG. 2 is a process flow diagram of a classification and classification method for multi-stage screening and dust removal of power coal according to an example of the present invention.
Detailed Description
The present invention will be further described with reference to the following examples and the accompanying drawings, but the present invention is not limited to the examples listed, and shall include equivalent modifications and variations of the technical solutions defined in the claims appended to the present application.
As shown in figure 1, the invention provides a grading and selecting method for multi-stage screening and dust removal of power coal, which comprises the following steps: raw coal is subjected to 50(25/13) mm dry classification by a rigid-flexible coupling screen surface elastic vibrating screen, materials above a sieve with the size of 50(25/13) mm enter a heavy-medium shallow groove separator for separation, the separated light and heavy products are subjected to medium removal and dehydration to obtain clean coal and gangue products, and materials below the sieve enter a relaxation screen with the size of 3mm or 2mm for dry classification; feeding materials on a relaxation sieve into a 3mm or 2mm rigid-flexible coupling elastic sieve surface vibrating sieve for dry powder removal, taking materials under the 3mm or 2mm rigid-flexible coupling elastic sieve surface vibrating sieve and materials under the 3mm or 2mm relaxation sieve surface vibrating sieve as coal blending products, and feeding light and heavy products obtained by separating the materials on the 50(25/13) -3(2) mm sieve through a heavy medium shallow groove separator into a centrifugal dehydrator for dehydration after medium removal to obtain clean coal and gangue products; and (3) purifying and recycling the medium subjected to medium removal and dehydration in a magnetic separator, classifying the coal slime water subjected to magnetic separation by a hydrocyclone, dehydrating and recycling coarse coal slime by an arc screen and a centrifugal machine, concentrating the fine coal slime, and performing pressure filtration and recycling by a pressure filter.
Each device shown in fig. 1 is a conventional device in the art, and the structural configuration of each device can be known according to the name or the function of the device, which is not described again, and of course, similar devices with the same function may be adopted in other embodiments.
Example 1
The application of the method of the invention is described below by way of a specific production example, as shown in fig. 2, which is only for the sake of understanding the solution of the invention and should not be understood as limiting the invention thereto:
a grading and selecting method for multi-stage screening and powder removal of power coal comprises the following steps:
step A1: raw coal enters a first rigid-flexible coupling screen surface elastic vibrating screen for dry classification, the size of a screen hole is 50mm, and materials with the size larger than 50mm on the screen enter a heavy-medium shallow groove separator for separation;
step B1: materials which are smaller than 50mm below the elastic vibrating screen with the first rigid-flexible coupling screen surface enter a flip-flop screen for dry classification, the size of the screen hole of the material is 3mm, materials which are 50-3mm above the flip-flop screen enter a second rigid-flexible coupling elastic screen surface vibrating screen for dry powder removal, the size of the screen hole of the material is 3mm, the materials which are 50-3mm above the screen after the powder removal enter a heavy medium shallow groove separator for separation, and the materials below the screen of the flip-flop screen and the materials below the screen of the 3mm rigid-flexible coupling elastic screen surface vibrating screen are used as coal blending products;
step C1: the heavy product of the separator with the heavy medium shallow slot of more than 50mm is used as a gangue product after being subjected to gangue removal, medium removal and dehydration by a gangue removal sieve; the light product of the heavy-medium shallow-groove separator is used as a clean coal product after being subjected to medium removal and dehydration by a clean coal medium removing sieve, the undersize dilute medium of the medium removing sieve enters a dilute medium barrel, and the undersize qualified medium of the medium removing sieve enters a medium combining barrel;
step D1: the heavy product after being sorted by the 50-3mm heavy-medium shallow slot sorting machine is dehydrated by a gangue medium removing sieve to be used as a gangue product, and the light product after being sorted is dehydrated by a centrifugal dehydrator to be used as a clean coal product after being subjected to medium removing by a clean coal medium removing sieve;
step E1: under-sieve shunt of the medium removing fixed sieve, centrifugal liquid of the coal slime centrifugal machine and under-sieve dilute medium of the medium removing sieve enter a dilute medium barrel, materials in the barrel are pumped into a magnetic separator by a pump, magnetically-separated concentrate enters a medium combining barrel, magnetically-separated tailings enter a coal slime bucket and then enter a hydrocyclone for classification;
step F1: the underflow classified by the hydrocyclone is dehydrated by a coarse coal slime sieve bend and a coarse coal slime centrifugal machine to obtain a coarse coal slime product; undersize materials of the coarse coal slime sieve bend, centrifugal liquid of the coarse coal slime centrifugal machine and overflow of the hydrocyclone enter a thickener together;
step G1: the overflow of the thickener is used as clear water and enters a circulating water system for recycling; the underflow of the thickener enters a coal slurry mixing barrel, materials in the barrel are pumped into a plate filter press by a pump, a coal slurry product is obtained after filter pressing, and filtrate of the plate filter press enters a filtrate barrel and is pumped back to the thickener by the pump.
Example 2
Steps E2 to G2 of this example were the same as steps E1 to G1 of example 1, except that in steps a2 to D2, the screen mesh size of the relaxation screen and the second rigid-flexible coupled screen surface elastic vibrating screen was 2 mm;
the method specifically comprises the following steps:
step A2: raw coal enters a first rigid-flexible coupling screen surface elastic vibrating screen for dry classification, the size of a screen hole is 50mm, and materials with the size larger than 50mm on the screen enter a heavy-medium shallow groove separator for separation;
step B2: materials with the size of less than 50mm below the elastic vibrating screen with the rigid-flexible coupling screen surface enter a flip-flop screen for dry classification, the size of the screen hole of the material is 2mm, materials with the size of 50-2mm above the screen of the flip-flop screen enter a second elastic vibrating screen with the rigid-flexible coupling screen surface for dry powder removal, the size of the screen hole of the material is 2mm, the materials with the size of 50-2mm above the screen after powder removal enter a heavy medium shallow groove separator for separation, and the materials below the screen of the flip-flop screen and the materials below the screen of the elastic vibrating screen with the rigid-flexible coupling screen surface of 2mm serve as coal blending products;
step C2: the heavy product of the separator with the heavy medium shallow slot of more than 50mm is used as a gangue product after being subjected to gangue removal, medium removal and dehydration by a gangue removal sieve; the light product of the heavy-medium shallow-groove separator is used as a clean coal product after being subjected to medium removal and dehydration by a clean coal medium removing sieve, the undersize dilute medium of the medium removing sieve enters a dilute medium barrel, and the undersize qualified medium of the medium removing sieve enters a medium combining barrel;
step D2: and (3) dehydrating the heavy product separated by the 50-2mm heavy-medium shallow slot separator by using a gangue medium removing sieve to obtain a gangue product, and dehydrating the separated light product by using a clean coal medium removing sieve to obtain a clean coal product after entering a centrifugal dehydrator to dehydrate.
Example 3
Steps E3 to G3 in this example are the same as steps E1 to G1 in example 1, except that in steps A3 to D3, the mesh size of the first rigid-flexible coupled screen surface elastic vibrating screen is 25 mm;
the method specifically comprises the following steps:
step A3: raw coal enters a rigid-flexible coupling screen surface elastic vibrating screen for dry classification, the size of a screen hole is 25mm, and materials larger than 25mm on the screen enter a heavy medium shallow groove separator for separation;
step B3: materials with the size of less than 25mm below the elastic vibrating screen with the rigid-flexible coupling screen surface enter a flip-flop screen for dry classification, the size of a screen hole of the material is 3mm, materials with the size of 25-3mm above the elastic vibrating screen with the rigid-flexible coupling screen surface enter the elastic vibrating screen with the rigid-flexible coupling screen surface for dry powder removal, the size of the screen hole of the material is 3mm, the materials with the size of 25-3mm above the screen after powder removal enter a heavy medium shallow groove sorting machine for sorting, and the materials below the screen of the flip-flop screen and the materials below the screen of the elastic vibrating screen with the rigid-flexible coupling screen surface with the size of 3mm serve as coal blending products;
step C3: the heavy product of the separator with the heavy medium shallow slot of more than 25mm is used as a gangue product after being subjected to gangue removal, medium removal and dehydration by a gangue removal sieve; the light product of the heavy-medium shallow-groove separator is used as a clean coal product after being subjected to medium removal and dehydration by a clean coal medium removing sieve, the undersize dilute medium of the medium removing sieve enters a dilute medium barrel, and the undersize qualified medium of the medium removing sieve enters a medium combining barrel;
step D3: and (3) dehydrating the heavy product separated by the 25-3mm heavy-medium shallow slot separator by using a gangue medium removing sieve to obtain a gangue product, and dehydrating the separated light product by using a clean coal medium removing sieve to obtain a clean coal product after entering a centrifugal dehydrator to dehydrate.
The rigid-flexible coupled screen surface elastic vibrating screens of the above examples 1-3 and the following comparative examples all adopt the modular casting rigid-flexible coupled elastic screen surface, and the expression "first" or "second" is only needed for the sake of distinction.
Comparative example
The comparative power coal separation method is a 6mm grading production process, and the steps E4-G4 of the method are the same as the steps E1-G1 of the example 1, except that in the steps A4-D4, the size of the screen holes of the relaxation screen is 6mm, and the materials on the relaxation screen are not subjected to the dry powder removal by the elastic vibrating screen with the rigid-flexible coupling screen surface in the next step;
the method specifically comprises the following steps:
step A4: raw coal enters a rigid-flexible coupling screen surface elastic vibrating screen for dry classification, the size of a screen hole is 50mm, and materials with the size larger than 50mm on the screen enter a heavy medium shallow groove separator for separation;
step B4: materials which are less than 50mm below the elastic vibrating screen on the rigid-flexible coupling screen surface enter a flip-flow screen for dry classification, the size of a screen hole of the flip-flow screen is 6mm, the materials which are 50-6mm above the flip-flow screen enter a heavy medium shallow groove separator for separation, and the materials below the flip-flow screen are used as a coal blending product;
step C4: the heavy product of the separator with the heavy medium shallow slot of more than 50mm is used as a gangue product after being subjected to gangue removal, medium removal and dehydration by a gangue removal sieve; the light product of the heavy-medium shallow-groove separator is used as a clean coal product after being subjected to medium removal and dehydration by a clean coal medium removing sieve, the undersize dilute medium of the medium removing sieve enters a dilute medium barrel, and the undersize qualified medium of the medium removing sieve enters a medium combining barrel;
step D4: and (3) dehydrating the heavy product separated by the 50-6mm heavy-medium shallow slot separator by using a gangue medium removing sieve to obtain a gangue product, and dehydrating the separated light product by using a clean coal medium removing sieve to obtain a clean coal product after entering a centrifugal dehydrator to dehydrate.
The effect data of example 1 and comparative example are shown in the following table 1:
TABLE 1
Through verification of the obtained product data, compared with the grading production process of 6mm in comparison, the raw coal washing rate is improved by about 10%, the coal slime content in the system is reduced by about 50% compared with the whole-size grading washing process, the sorting precision of the heavy medium system is improved, and the possible deviation value E value of the 50mm heavy medium system is improved to 0.022g/cm3The process has the characteristics of stable and efficient production, low energy consumption, low chemical consumption, large treatment capacity and the like, and the crude coal slime of the sticky and wet easily-argillized power coal has large amount and is easily argillized when meeting water, and the wet-method desliming can greatly increase the coal slime content in the system。
Those skilled in the art understand that the raw coal washing rate, the screening efficiency, the desliming efficiency, the coal slime content, the separation precision and the deviation value E can be obtained by detection by adopting a corresponding conventional method in the field, and are not described again.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. Not all embodiments are exhaustive. All obvious changes or modifications of the technical solution of the present invention are within the spirit of the present invention.
Claims (10)
1. A grading and selecting method for multi-stage screening and powder removal of power coal is characterized by comprising the following steps: the method comprises the following steps:
1) raw coal is screened by a first rigid-flexible coupling screen surface elastic vibrating screen and classified by a dry method, so as to obtain a first oversize material with the particle size larger than the size of a screen hole and a first undersize material with the particle size smaller than the size of the screen hole, the first oversize material enters a heavy-medium shallow groove separator for separation, and a light product and a heavy product obtained after separation are subjected to medium removal to respectively obtain clean coal, gangue and a coal slime water medium system; the screen hole size of the first rigid-flexible coupling screen surface elastic vibrating screen is selected from one of 50mm, 25mm and 13 mm;
2) step 1) screening the first undersize material in a relaxation sieve to obtain a second oversize material with the particle size larger than the size of a sieve pore and a second undersize material with the particle size smaller than the size of the sieve pore by dry classification, wherein the sieve pore size of the relaxation sieve is 2mm or 3 mm;
3) step 2) screening the second oversize material by a second rigid-flexible coupling elastic screen surface vibrating screen to remove powder by a dry method, and obtaining a third oversize material with the particle size larger than the size of a screen hole and a third undersize material with the particle size smaller than the size of the screen hole; the materials on the third screen after the powder removal enter a heavy-medium shallow groove separator for separation, and the light products and the heavy products obtained by separation are subjected to medium removal and dehydration to respectively obtain clean coal, gangue and a coal slime water medium system; the size of the sieve pore of the second rigid-flexible coupling elastic sieve surface vibrating sieve is 2mm or 3 mm;
4) taking the third undersize material obtained in the step 3) and the second undersize material obtained in the step 2) as a coal blending product, wherein the particle sizes of the second undersize material and the third undersize material are less than 2mm or 3 mm;
5) step 1) the coal slime aqueous medium system that obtains through taking off the medium to and step 3) the coal slime aqueous medium system that obtains through taking off the medium and dehydration gets into the magnet separator and purifies the recovery, obtain the coal slime water after the magnetic separation, the coal slime water obtains coarse coal mud and fine coal mud through grading, coarse coal mud dehydration is retrieved, fine coal mud is retrieved through concentrated back filter-pressing.
2. The classification enrollment method as claimed in claim 1, characterized in that: in the step 1), the first rigid-flexible coupling elastic screen surface vibrating screen surface adopts a modular casting rigid-flexible coupling elastic screen surface or a rigid-flexible coupling elastic rod screen surface; the screen hole size of the first rigid-flexible coupling screen surface elastic vibrating screen is preferably 50mm or 25 mm.
3. The classification enrollment method as claimed in claim 1 or 2, characterized in that: in the step 3), the screen surface of the second rigid-flexible coupling elastic screen surface vibrating screen adopts a modular pouring rigid-flexible coupling elastic screen surface or a rigid-flexible coupling elastic rod screen surface, and the screen hole size of the second rigid-flexible coupling screen surface elastic vibrating screen is preferably 3 mm.
4. A method of rating entries according to any one of claims 1 to 3, wherein: the heavy product obtained by the heavy-medium shallow-groove separator in the step 1) is subjected to gangue removal and medium removal through a gangue removal sieve to obtain a gangue product and a coal slime water medium system; and (3) carrying out the dense-medium shallow-slot separator on the light product to obtain a clean coal product and a coal slime water medium system after the clean coal is subjected to medium removal by a clean coal medium removal sieve.
5. The classification enrollment method as claimed in any one of claims 1 to 4, characterized in that: performing gangue removal screening and medium removal on the heavy products subjected to the heavy medium shallow groove sorting machine in the step 3) to obtain gangue products and a coal slime water medium system; and (3) carrying out medium removal by a clean coal medium removal sieve and dehydration by a centrifugal dehydrator on the light product of the heavy-medium shallow-slot separator to obtain a clean coal product and a coal slime water medium system.
6. The classification enrollment method as claimed in claim 4 or 5, characterized in that: in the steps 1) and 3), undersize dilute media of the gangue and clean coal medium removing sieves enter the dilute medium barrel, and undersize qualified media of the gangue and clean coal medium removing sieves enter the qualified medium barrel.
7. The classification enrollment method as claimed in claim 5, characterized in that: in the step 5), the undersize shunt of the gangue and clean coal medium removal sieves, the centrifugate of the centrifugal dehydrator, the undersize dilute medium of the gangue and clean coal medium removal sieves in the steps 1) and 3) enter a dilute medium barrel, the material in the dilute medium barrel enters a magnetic separator for magnetic separation, the magnetic concentrate after magnetic separation enters a qualified medium barrel, the magnetic tailings enter a coal slime bucket and then enter a grading swirler for grading to obtain overflow and underflow.
8. The classification enrollment method as claimed in claim 7, wherein: in the step 5), the classifying cyclone is a hydrocyclone.
9. The dynamic stage election method according to claim 7, characterized in that: the underflow classified by the classification cyclone is dehydrated by a coal slime sieve and a coal slime centrifugal machine in sequence to obtain a coarse coal slime product; undersize materials of the coal slime sieve, centrifugal liquid of the coal slime centrifugal machine and overflow of the grading cyclone enter a thickener for concentration and filter pressing.
10. The classification enrollment method as claimed in claim 9, wherein: the concentration and pressure filtration comprises: the overflow of the thickener is used as clear water and enters a circulating water system for recycling; the underflow of the thickener enters a coal slime mixing barrel, the materials in the barrel enter a filter press, a coal slime product is obtained after filter pressing, and the filtrate of the plate filter press enters a filtrate barrel and then enters the thickener.
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