AU2021100676A4

AU2021100676A4 - Efficient desliming and separating method

Info

Publication number: AU2021100676A4
Application number: AU2021100676A
Authority: AU
Inventors: Guangwen CUI
Original assignee: Shandong University of Science and Technology
Current assignee: Shandong University of Science and Technology
Priority date: 2021-02-03
Filing date: 2021-02-03
Publication date: 2021-05-13
Anticipated expiration: 2029-02-03

Abstract

The present disclosure provides an efficient desliming and separating method. Equipment used for the efficient desliming and separating method includes a raw coal classifying and desliming screen, a water-only cyclone, classifying equipment, dense medium equipment, floating equipment, a mixing barrel, a coal slime barrel, a centrifuge, a magnetic separator, a bow screen, a high frequency screen, a medium draining screen, a thickening cyclone and a pressure filter. The efficient desliming and separating method includes the steps that raw coal enters the classifying and desliming screen to be subjected to classified desliming by a wet method, screened fine-fraction coal slime of 1 mm-5 mm enters a water-only system through the coal slime barrel for separation, and overflow and underflow are obtained; the overflow enters the classifying equipment, and oversize products for the classifying equipment enter the centrifuge for dehydration to produce clean coal; the underflow enters the high frequency screen for dehydration, and undersize products and undersize products for the classifying equipment converge to enter floating machine equipment for fine coal slime separating; oversize products for the high frequency screen and the oversize products for the desliming screen enter the dense medium system together; floating clean coal after dehydration treatment by the pressure filter is mixed with the clean coal after centrifugal dehydration to be used as final clean coal, and centrifugate returns to the coal slime barrel to form a closed loop for separating once again; and floating tailings enter a tailings thickener for thickening and dehydrating, and are subjected to dehydration by the pressure filter to become coal slime, and pressure filter filtrate and thickening liquor are used as circulating water. The method increases treatment capacity and separating accuracy of the dense medium cyclone, reduces medium depletion quantity, conveniently adjusts density of suspension, reduces occurrence of an additional ash content of clean coal as possible, increases economic benefits of enterprises and reasonably uses coal resources. 11 DRAWINGS Raw coal Classic ing and deslim g screen Coal slime barrel Water-onli cyclone Class fying High f quency equi ment sc een Cen ifuge -+ 7Flo ing Press re filter ThiDkener Press re filter Clean coal Circulating Coal slime Densysmedium water FIG. 1 Flowchart of an efficient desliming and separating method Page 1 of3

Description

DRAWINGS

Raw coal Classic ing and deslim g screen

Coal slime barrel

Water-onli cyclone

Class fying High f quency equi ment sc een

Cen ifuge -+ 7Flo ing

Press re filter

ThiDkener Press re filter

Clean coal Circulating Coal slime Densysmedium water

FIG. 1 Flowchart of an efficient desliming and separating method

Page 1 of3

EFFICIENT DESLIMING AND SEPARATING METHOD TECHNICAL FIELD

The present disclosure relates to the technical field of a coal separating method, in particular to a coal desliming and separating technique.

BACKGROUND

Energy is an important basic resource for development of human society. China is high in energy consumption, and coal is irreplaceable and achieves supporting effect for China's economic and social development, so that rational and efficient use of the coal has become an energy development direction of China. In recent years, with increment of a degree of mechanized coal mining, a content of fine-fraction coal in raw coal is continuously increased, in addition, after the raw coal is crushed, massive secondary coal slime is generated, a dense medium cyclone is poor in separating effects on fine-fraction fed materials in the raw coal, and especially under a condition of high content of fine fraction materials being smaller than 1 mm, the fine-fraction materials can generate mismatching to a certain extent in a separating method. On one hand, high content of fine-fraction coal slime in a coal preparation system affects treatment capacity of the dense medium cyclone, thereby causing reduction of separating accuracy of the fine-fraction coal slime and causing a problem of an additional ash content of primary washed clean coal. On the other hand, a content of middlings slime is too high, and after fine-fraction coal and medium powder and circulating water are sufficiently mixed, viscosity is greatly increased to cause difficulty in medium drainage, increase of concentration and viscosity of materials fed in a magnetic separator, reduction of magnetic separation efficiency, rise of medium depletion and increase of coal washing cost.

At present, coal preparation in China mainly adopts technological processes: a process of performing treatment through a non-desliming non-pressure three-product dense medium cyclone for raw coal and coal slime recovery, and a process of performing jigging primary separation and performing selection through a dense medium cyclone. But the two technologies both have disadvantages of being complex in flow, low in separating accuracy, high in medium depletion, high in investment and inconvenient in management. To solve problems caused by too much fine-fraction coal slime and conform to indexes required by environmental protection, aiming at defects in prior art and equipment, the present disclosure provides a united separating process of performing desliming before separating, performing treatment with a water-only cyclone and performing treatment with a dense medium cyclone, to increase treatment capacity and separating accuracy of the dense medium cyclone, reduce medium depletion quantity, conveniently adjust density of suspension, reduce occurrence of an additional ash content of clean coal as possible, increase economic benefits of enterprises and reasonably use coal resources.

The process is diversified in realization flow, products are diversified in structure, and coal preparation plants are large in scale and high in mechanization and intelligence.

SUMMARY

An objective of the present disclosure is to provide an efficient desliming and separating method, namely a united method of performing desliming before separation, performing treatment with a water-only cyclone and performing treatment with a dense medium cyclone aiming at defects in existing equipment and prior art. The method increases treatment capacity and separating accuracy of the dense medium cyclone, reduces medium depletion quantity, conveniently adjusts density of suspension, reduces occurrence of an additional ash content of clean coal as possible, increases economic benefits of enterprises and reasonably uses coal resources.

The present disclosure has a technical solution:

1. the present disclosure provides an efficient desliming and separating method. Equipment used for the efficient desliming and separating method includes a raw coal classifying and desliming screen, a water-only cyclone, classifying equipment, dense medium equipment, floating equipment, a mixing barrel, a coal slime barrel, a centrifuge, a magnetic separator, a bow screen, a high frequency screen, a medium draining screen, a thickening cyclone and a pressure filter. The efficient desliming and separating method includes specific technological steps as follows:

a: classified desliming: raw coal on a colliery enters the classifying and desliming screen in a main workshop to be subjected to classified desliming by a wet method, screened fine-fraction coal slime of 1 mm-5 mm enters a water-only system through the coal slime barrel, and oversize products enter a dense medium system;

b: water-only separating: materials in a coal slime barrel enter the water-only cyclone for separating to obtain overflow and underflow; the overflow enters the classifying equipment, and oversize products for the classifying equipment enter the centrifuge for dehydration to produce clean coal; the underflow is subjected to dehydration treatment by the high frequency screen, undersize products and undersize products for the classifying equipment converge to enter floating machine equipment for fine coal slime separating; oversize products for the high frequency screen enter the dense medium system; floating clean coal after dehydration treatment by the pressure filter is mixed with the clean coal after centrifugal dehydration to be used as final clean coal, and centrifugate returns to the coal slime barrel to form a closed loop for separating once again; and floating tailings enter a tailings thickener for thickening and dehydrating, and are subjected to dehydration by the pressure filter to become coal slime, and pressure filter filtrate and thickening liquor are used as circulating water.

c: the dense medium system: the dense medium system can select a non-pressure three-product dense medium cyclone, a pressurized three-product dense medium cyclone and a pressurized two product dense medium cyclone, and the pressurized two-product dense medium cyclone and the non-pressure three-product dense medium cyclone are taken as examples.

d: the pressurized two-product dense medium cyclone: when passing through the mixing barrel, materials are pumped into a primary washing two-product dense medium cyclone by a pump, for separating to obtain gangue and intermediate products; underflow enters the bow screen for dehydration treatment to obtain oversize products and qualified media, the oversize products enter the medium draining screen for medium draining treatment to obtain final gangue and gangue diluted media; overflow enters the bow screen for dehydration treatment to obtain oversize products and qualified media, and the oversize products enter the medium draining screen for medium draining treatment to obtain intermediate product diluted media and intermediate products; undersize products are subjected to flow diversion to obtain two portions of the qualified media, one portion of media, the gangue qualified media and the gangue diluted media enter a gangue magnetic separator for magnetic separation to obtain gangue magnetic tails and qualified media; the gangue magnetic tails are subjected to thickening and dehydrating treatment by a thickening cyclone and the centrifuge, and are mixed with the gangue to obtain final gangue, and underflow for the thickening cyclone returns to a floating tailings thickener; the intermediate product diluted media are subjected to magnetic separation by the magnetic separator to obtain intermediate product magnetic tails and qualified media, the qualified media, the other portion of media and the gangue qualified media enter a qualified medium barrel and return to a primary washing mixing barrel to form a closed loop;

when passing through a rewashing mixing barrel, intermediate products are pumped into a rewashing two-product dense medium cyclone by a pump for separating once again; underflow is subjected to dehydration treatment by the bow screen to obtain oversize products and qualified media, and the oversize products are subjected to medium draining treatment by the medium draining screen to obtain middlings and middlings diluted media; overflow is subjected to dehydration treatment by the bow screen to obtain oversize products and qualified media, the oversize products are subjected to medium draining treatment by the medium draining screen to obtain clean coal diluted media and clean coal, and the clean coal diluted media are subjected to magnetic separation by a clean coal magnetic separator to obtain clean coal magnetic tails and qualified media; clean coal is subjected to dehydration by the centrifuge to obtain final clean coal; undersize products are subjected to flow diversion to obtain two portions of qualified media, one portion of media, middlings qualified media and middlings diluted media enter a middlings magnetic separator for magnetic separation to obtain middlings magnetic tails and qualified media; the qualified media, the other portion of the media and the clean coal qualified media enter the qualified medium barrel and return to the rewashing mixing barrel to form a closed loop; the middlings magnetic tails are subjected to thickening and dehydrating treatment by a thickening cyclone and the centrifuge and are mixed into middlings, and the middlings are subjected to dehydrating treatment by the centrifuge to obtain final middlings; and intermediate product magnetic tails, middlings thickening cyclone underflow, middlings centrifugate, clean coal magnetic tails and clean coal centrifugate converge and return to a classifying and desliming system for separating once again; and e: the non-pressure three-product dense medium cyclone: materials directly enter the non pressure three-product dense medium cyclone for separating to obtain clean coal, middlings and gangue; the clean coal is subjected to dehydration treatment by the bow screen to obtain oversize products and qualified media, and the oversize products are subjected to medium draining treatment by the medium draining screen to obtain clean coal diluted media and clean coal; the qualified media are subjected to flow diversion, one portion of the qualified media and the clean coal diluted media enter the clean coal magnetic separator for magnetic separation to obtain clean coal magnetic tails and qualified media, and the other portion of the qualified media and the qualified media enter the cyclone to be used as circulating media; and the clean coal is subjected to dehydration treatment by the centrifuge to be used as final clean coal.

The middlings are subjected to dehydration treatment by the bow screen to obtain oversize products and qualified media, and the oversize products are subjected to medium draining treatment by the medium draining screen to obtain middlings diluted media and middlings; the middlings diluted media enter the middlings magnetic separator for magnetic separation to obtain middlings magnetic tails and qualified media, the middlings magnetic tails enter the thickening cyclone for thickening, and overflow is mixed with the middlings for dehydration treatment by the centrifuge to obtain final middlings; and thickening liquor, middlings liquor, clean coal centrifugate and clean coal magnetic tails return to the primary washing desliming system for separating once again.

Gangue is subjected to dehydration treatment by the bow screen to obtain oversize products and qualified media, and the oversize products are subjected to medium draining treatment by the medium draining screen to obtain gangue diluted media and gangue; the gangue diluted media enter a gangue magnetic separator for magnetic separation to obtain gangue magnetic tails and qualified media, the gangue magnetic tails enter the thickening cyclone for thickening, and overflow is mixed with the centrifuge for dehydration treatment to obtain final gangue; and the centrifugate and the thickening liquor enter a tailings thickener for thickening.

Preferably, the water-only cyclone uses three-taper-angle water-only cyclone, effective separating particle size is 6-0.2 mm, and pressure during separating is 0.04-0.1 MPa.

Preferably, the classifying and desliming screen is 1-5mm in hole diameter, and a ratio of addition amount of water to weight of materials is 1:1.5.

Preferably, the classifying equipment is a high frequency vibration fine screen, screen holes are 0.2mm in diameter, and sieving efficiency is 24%-41%.

Preferably, the bow screen is preferably 0.35-0.75 mm in screen hole diameter, dehydration treatment time is preferably 20-40 s, the medium draining screen is 0.5-2 mm in hole diameter, and treatment capacity is 1-4 t/(h.m 2).

Preferably, magnetic field intensity of the magnetic separator is 80-400 kA/m.

Preferably, a solid-to-liquid ratio of the thickening liquor is preferably 300-700 g/L.

Preferably, the dense medium cyclone has no special requirements for types, because of different advantages of characteristics and separating mechanisms of two dense medium technologies namely pressurized feeding and non-pressure feeding, the technologies need be analyzed specifically according to coal quality conditions, product structure requirements and customer requirements during selection and are preferentially selected.

Preferably, the clean coal after water-only separating can be mixed with clean coal after dense medium separating and can also be sold alone.

Preferably, dehydrating equipment, medium draining equipment, thickening equipment and floating pressure filtration equipment are general equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flowchart of a method disclosed by the present disclosure;

FIG. 2 shows a technological flowchart of a pressurized two-product dense medium cyclone; and

FIG. 3 shows a technological flowchart of a non-pressure three-product dense medium cyclone.

DETAILED DESCRIPTION

Raw coal on a colliery enters a classifying and desliming screen in a main workshop to be subjected to classified desliming by a wet method, and screened fine-fraction coal slime of1mm mm enters a water-only cyclone through a coal slime barrel for separating to obtain overflow and underflow; the overflow enters classifying equipment, oversize products for the classifying

I; equipment enter a centrifuge for dehydration to produce clean coal; the underflow enters a high frequency screen for dehydration treatment, undersize products and undersize products for the classifying equipment converge to enter floating machine equipment for coal slime floating; oversize products for the high frequency screen and oversize products for the desliming screen enter a dense medium system together; floating clean coal is subjected to dehydration treatment by a pressure filter and is mixed with the clean coal after centrifugal dehydration to be used as final clean coal, and centrifugate returns to the coal slime barrel to form a closed loop for separating once again; and floating tailings enter a tailings thickener for thickening and dehydrating, and are subjected to dehydration by the pressure filter to become coal slime, and pressure filter filtrate and thickening liquor are used as circulating water.

Because of different characteristics of technological flows and separating mechanisms of two systems namely pressurized feeding and non-pressure feeding of dense media, the dense media need be analyzed specifically according to coal quality conditions, product structure requirements and customer requirements during selecting and are preferentially selected.

With reference to FIG. 2, an implementation manner of the pressurized two-product dense medium cyclone is described: when passing through the mixing barrel, materials are pumped into a primary washing two-product dense medium cyclone by a pump, for separating to obtain gangue and intermediate products; underflow enters the bow screen for dehydration treatment to obtain oversize products and qualified media, the oversize products enter the medium draining screen for medium draining treatment to obtain final gangue and gangue diluted media; overflow enters the bow screen for dehydration treatment to obtain oversize products and qualified media, and the oversize products enter the medium draining screen for medium draining treatment to obtain intermediate product diluted media and intermediate products; undersize products are subjected to flow diversion to obtain two portions of the qualified media, one portion of media, the gangue qualified media and the gangue diluted media enter a gangue magnetic separator for magnetic separation to obtain gangue magnetic tails and qualified media; the gangue magnetic tails are subjected to thickening and dehydrating treatment by a thickening cyclone and the centrifuge, and are mixed with the gangue to obtain final gangue, and underflow for the thickening cyclone returns to a floating tailings thickener; the intermediate product diluted media are subjected to magnetic separation by the magnetic separator to obtain intermediate product magnetic tails and qualified media, the qualified media, the other portion of media and the gangue qualified media enter a qualified medium barrel and return to the primary washing mixing barrel to form a closed loop for separating again;

when passing through a rewashing mixing barrel, intermediate products are pumped into a rewashing two-product dense medium cyclone by a pump for separating once again; underflow enters the bow screen for dehydration treatment to obtain oversize products and qualified media, and the oversize products enter the medium draining screen for medium draining treatment to obtain middlings and middlings diluted media; overflow enters the bow screen for dehydration treatment to obtain oversize products and qualified media, the oversize products enter the medium draining screen for medium draining treatment to obtain clean coal diluted media and clean coal, and the clean coal diluted media are subjected to magnetic separation by a clean coal magnetic separator to obtain clean coal magnetic tails and qualified media; clean coal is subjected to dehydration by the centrifuge to obtain final clean coal; undersize products are subjected to flow diversion to obtain two portions of qualified media, one portion of media, middlings qualified media and middlings diluted media enter a middlings magnetic separator for magnetic separation to obtain middlings magnetic tails and qualified media; the qualified media, the other portion of the media and the clean coal qualified media enter the qualified medium barrel and return to the rewashing mixing barrel to form a closed loop; the middlings magnetic tails are subjected to thickening and dehydrating treatment by a thickening cyclone and the centrifuge and are mixed into middlings, and the middlings are subjected to dehydrating treatment by the centrifuge to obtain final middlings; and intermediate product magnetic tails, middlings thickening cyclone underflow, middlings centrifugate, clean coal magnetic tails and clean coal centrifugate converge and return to a classifying and desliming system.

With reference to FIG.3, an implementation manner of the non-pressure three-product dense medium cyclone is described: materials directly enter the non-pressure three-product dense medium cyclone for separating to obtain clean coal, middlings and gangue;

the clean coal is subjected to dehydration treatment by the bow screen to obtain oversize products and qualified media, and the oversize products are subjected to medium draining treatment by the medium draining screen to obtain clean coal diluted media and clean coal; the qualified media are subjected to flow diversion, one portion of the qualified media and the clean coal diluted media enter the clean coal magnetic separator for magnetic separation to obtain clean coal magnetic tails and qualified media, and the other portion of the qualified media and the qualified media enter the cyclone to be used as circulating media; and the clean coal is subjected to dehydration treatment by the centrifuge to be used as final clean coal.

The above descriptions are merely preferred implementations of the present disclosure. It should be noted that a person of ordinary skilled in the art may further make several improvements and modifications without departing from a principle of the present disclosure, but such improvements and modifications should be deemed as falling within the protection scope of the present disclosure.

R

Claims

What is claimed is:

1. A coal desliming and separating method, comprising:

performing separating treatment on coal slime through a three-taper-angle water-only cyclone to obtain overflow and underflow, wherein the three-taper-angle water-only cyclone has separating pressure of 0.04-0.1 MPa;

performing classifying treatment on the overflow to obtain first large particle size objects and first small particle size objects, wherein the first large particle size objects are first refined coal and have a particle size of 0.5-3 mm, and the first small particle size objects have a particle size smaller than 0.5 mm;

performing sieving treatment on the underflow to obtain second large particle size objects and second small particle size objects, wherein the second large particle size objects are coal particles, are guided into a dense medium system, and have particle size of 0.5-3 mm, and the second small particle size objects have particle size smaller than 0.5 mm; and

performing floating on the first small particle size objects and the second small particle size objects to obtain second refined coal and waste coal, wherein the waste coal is coal slime slags;

wherein the coal slime has a particle size smaller than or equal to 5 mm.

2. The method according to claim 1, wherein the classifying treatment is implemented by a cyclone, a deep taper classifying machine, a bow screen or a high frequency vibration screen;

wherein the sieving treatment is implemented by a high frequency vibration screen;

wherein the floating is implemented by a floating column or a mechanical stirring type floating machine.

3. The method according to claim 1 or claim 5, wherein floating comprises:

mixing the first small particle size objects with the second small particle size objects and water to obtain slime materials to be floated, having a mass concentration of 50-120 g/L; and

performing floating on the slime materials to be floated.

4. The method according to claim 1 or claim 2, wherein in the slime materials to be floated, a floating drug for floating has mass of 0.6-1.5 kg/t.

5. The method according to claim 1, wherein after floating, the method further comprises: performing solid-liquid separation on the second refined coal to obtain second refined coal in solid state; and sequentially performing thickening and solid-liquid separation on the waste coal to obtain the coal slime slags.

in