AU2019429000B2

AU2019429000B2 - Concentration and separation method for raw coal of coal-to-liquid fuels on the basis of water medium separation

Info

Publication number: AU2019429000B2
Application number: AU2019429000A
Authority: AU
Inventors: Yijun CAO; Xiahui GUI; Wei Jin; Jiongtian Liu; Yaowen XING
Original assignee: China University of Mining and Technology CUMT
Current assignee: China University of Mining and Technology CUMT
Priority date: 2019-02-12
Filing date: 2019-04-22
Publication date: 2021-11-25
Anticipated expiration: 2039-04-22
Also published as: WO2020164187A1; CN109746116B; AU2019429000A1; CN109746116A

Abstract

A concentration and separation method for raw coal of coal-to-liquid fuels on the basis of water medium separation, comprising the following steps: a 3 mm classification operation, jig separation, TBS separation, and dewatering of respective products. The method comprises: performing separation on coal pieces greater than 3 mm in size by means of a jig concentrator (B) so as to obtain a clean lump coal product (2) and a coal tailings product (3); performing separation on coal pieces less than 3 mm in size by means of a TBS separator (C) so as to obtain a clean coal dust product (4) and a coal tailings product (5); and separately dewatering each respective product so as to obtain a final product.

Description

COAL-TO-LIQUID RAW COAL ENRICHMENT SEPARATION METHOD BASED ON WATER MEDIUM SEPARATION TECHNICAL FIELD

The present invention relates to a separation method, and more particularly, to a

coal-to-liquid raw coal enrichment separation method based on water medium separation,

applied to the field of low-rank coal separation.

BACKGROUND

Coal, petroleum and natural gas are the three main fossil energy sources in China, and

their development and utilization play a decisive role in the economic development of China.

The proven petroleum reserves in China are extremely limited. More than half of the

petroleum consumption depends on import every year, and the import volume is still rising.

On the other hand, coal resources in China are relatively abundant, and coal is still the most

stable and reliable energy source for some time to come. Moreover, China has quite abundant

low-rank coal reserves suitable for direct coal liquefaction. In the coal utilization process, this

part of low-rank coal may be liquefied into liquid fuel to replace petroleum to reduce the

dependence foreign petroleum; therefore, it is particularly important to study the enrichment

technology of liquefaction active components of the low-rank coal, and it has important

strategic significance in improving the current situation of petroleum shortage in China.

From the perspective of coal petrology, coal for low-rank coal liquefaction includes three

coal rock macerals: a vitrinite, an inertinite and an exinite, wherein the vitrinite and the

inertinite are the main components, and the exinite content is very low and generally less than

1%. The vitrinite and the exinite are active components of low-rank coal liquefaction, the

inertinite is an inactive component of low-rank coal liquefaction, and the order of the

liquefaction activity is exinite>vitrinite>inertinite, the enrichment of the coal rock

components of the exinite and the vitrinite (mainly the vitrinite) in the low-rank coal may

enhance the liquefaction reaction activity and increase the recovery rate of liquefied oil.

Studies have shown that every 10% increase of the active coal rock component content may increase the recovery rate of the oil by 4%, so that the economic benefits of enterprises are greatly increased. Therefore, enrichment of the coal rock components has great significance in liquefaction of the low-rank coal.

There are a large number of low-ash, low-sulfur and low-phosphorous high-quality

low-rank liquefaction coal in Shaanxi, Shanxi, Inner Mongolia, Gansu, Qinghai, Ningxia and

the like in China. The low-rank coal has high reaction activity and may serve as a petroleum

substitute after being directly liquefied. At present, the research field of the coal-to-liquid

technology has become wider and wider among scholars and enterprises, and the research

problems have become deeper and deeper. The one-million-ton coal-to-liquid demonstration

project implemented by Shenhua Coal to Liquid and Chemical CO., LTD. is a strategic

exploration of the coal-to-liquid technology. The coal for Shenhua coal-to-liquid has a special

coal-to-liquid coal preparation plant, and the clean coal selected by the coal preparation plant

serves as coal-to-liquid raw coal; however, the clean coal produced by the coal preparation

plant has high inertinite content, which has always restricted the increase of the recovery rate

of oil and also limited the rise in profit margins. Therefore, it is necessary to further enrich the

active components in this part of clean coal. At present, in the existing process,

vitrinite-enriched and inertinite-enriched coal is obtained by a heavy medium cyclone of

-0.5 mm and a flotation process of -0.5 mm after the raw coal is selectively crushed;

however, the coal for Shenhua coal-to-liquid belongs to low-rank coal and has the following

characteristics: due to the molecular structure of the low-tank coal, the hydrophilicity

difference is small; and the content of the active components is larger in coarse fraction and is

small in fine fraction, especially -0.5 mm. Therefore, the flotation link is of little significance

in enrichment of coal rock components. Particles with fine fraction such as 3-0.5 mm are

difficult to effectively separate due to higher separation lower limit of the heavy medium

cyclone. Moreover, it is necessary to add the medium recovering process, the process is

tedious and the investment cost is increased. Therefore, developing a technological process

which can effectively separate the liquefaction raw coal of 50-0.5 mm and is simple in

process and small in investment has become an urgent problem to be solved in the coal rock

enrichment process.

SUMMARY OF THE INVENTION

Technical problem: for the defects in the above technology, the present invention

provides a coal-to-liquid raw coal enrichment separation method based on water medium

separation, with low cost, high separation efficiency, reasonable process and significant

economic benefit.

Technical solution: according to the present invention, the coal-to-liquid raw coal

enrichment separation method based on water medium separation includes the following

steps:

a. feeding raw coal into a classifying screen to perform 3 mm classification, so as to

obtain two coal materials with particle size greater than 3 mm and particle size less than 3

mm;

b. feeding the coal material with particle size greater than 3 mm into a jigging machine

(B) to perform separation, after layering heavy and light products in the jigging machine (B),

feeding the light product into a clean coal dewatering screen (D) through an overflow weir to

dewater and output an oversize block clean coal product and undersize water, discharging the

heavy product out of the jigging machine by oversize discharging and screen-penetrating

discharging to enter a tail coal dewatering screen, dewatering in the tail coal dewatering

screen and outputting an oversize tail coal product and undersize water, feeding the undersize

water output by the clean coal dewatering screen and the tail coal dewatering screen into a

dredging sump respectively, and separating the undersize water into circulating water and

underflow by the dredging sump and by precipitation overflowing, wherein the circulating

water is used in the separation link, and the underflow is pumped into a tail coal filter press by

a pump for filter pressing;

c. feeding the coal material with particle size less than 3 mm from an upper end of a tank

body of a TBS along a tangent line, enabling the coal material with particle size less than 3

mm to do interference settling movement in the teetered bed separator (TBS) and realize

separation according to density, discharging a low-density light product from the TBS along

with overflow to enter a sieve bend of 0.5 mm for screening, discharging a high-density product of the TBS from a discharging valve at the bottom of the TBS to enter a tail coal centrifugal machine, dewatering the high-density heavy product by the tail coal centrifugal machine (I) to obtain a tail coal product and centrifugal machine centrifugate a, feeding an oversize material screened by the sieve bend into a clean coal centrifugal machine to dewater to obtain a powder clean coal product and centrifugal machine centrifugate b, and returning the centrifugal machine centrifugate b to the TBS for recycling; and d. feeding the underflow of the dredging sump, the centrifugate of the tail coal centrifugal machine and a undersize product of the sieve bend into the tail coal filter press for filter pressing, and dewatering to obtain a tail coal slime product with particle size less than

0.5 mm, wherein filtrate serves as the circulating water for recycling.

A separation density of the TBS (C) is marked by a vitrinite that the content of less than

1.45g/cm3 density level accounts for 90%, the vitrinite coal content being 57%, and that the

content of greater than 1.45g/cm 3 density level accounts for 10%, the vitrinite content being

57%.

The coal material with particle size greater than 3 mm after separation by the TBS (C)

accounts for 93%, the vitrinite content being 55%; and the coal material with particle size less

than 3 mm accounts form 7%, the vitrinite content being 30%.

The whole separation process only uses a water medium, without adding a medium

recovering process. The tail coal slime product (6) with particle size less than 0.5 mm directly serves as a tail

coal product without being subjected to flotation.

The present invention has the following beneficial effects: in the technical solution of the

present invention, after the raw coal of 3 mm is classified, the coal of +3 mm is subjected to

jigging separation, the raw coal of -3 mm is subjected to TBS separation, the separation

density is 1.45g/cm 3, and the vitrinite coal and the inertinite coal are effectively separated, so

that the content of coal-to-liquid inactive component inertinite coal in the clean coal is

reduced, and the raw coal meets the secondary standard of direction liquefaction, that is, the

inertinite content is 15% to 45%, thereby increasing the oil recover rate in the subsequent

coal-to-liquid link and increasing economic benefits for enterprises. In the technological process, the raw coal of 3~0.5 mm is subjected to TBS separation with good separation effect on fine fraction, the jigging separation has sufficient separation precision on the coarse fraction of +3 mm, and the coal of -0.5 mm directly serves as tail coal due to high inertinite content, so that the problem that the existing process has low efficiency on fine fraction coal enrichment is solved, effective separation of the clean coal and tail coal can be realized without adding a medium, the flotation link of -0.5 mm is reduced, and simple process, convenient operation and small investment are achieved. When the coal-to-liquid low-rank coal is classified and separated, good separation effect can be achieved at 50~3 mm, 3~0.5 mm and -0.5 mm, thus increasing the vitrinite coal content of the clean coal and having obvious advantage in enrichment of the vitrinite in the coal-to-liquid low-rank coal.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flow block diagram of a separation process according to the present invention;

and

FIG. 2 is a schematic structural diagram of separation equipment according to the present

invention.

In the drawings: 1-raw coal, 2-block clean coal product, 3-tail coal product, 4-powder

clean coal product, 5-tail coal product, 6-tail coal slime product, 7-circulating water,

A-classifying screen, B-jigging machine, C-TBS, D-clean coal dewatering screen, E-tail coal

dewatering screen, F-dredging sump, G-sieve bend, H-clean coal centrifugal machine, I-tail

coal centrifugal machine, J-tail coal filter press, a-tail coal centrifugal machine centrifugate,

b-clean coal centrifugal machine centrifugate.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The implementation of the present invention is described in detail below with reference

to the accompanying drawings.

As shown in FIG. 1 and FIG. 2, the coal-to-liquid raw coal enrichment separation

method based on water medium separation according to the present invention includes the

following steps: a. raw coal 1 is fed into a classifying screen A to perform 3 mm classification, so that two coal materials with particle size greater than 3 mm and particle size less than 3 mm are obtained; b. the coal material with particle size greater than 3 mm is fed into a jigging machine B to perform separation, after heavy and light products in the jigging machine B are layered, the light product is fed into a clean coal dewatering screen D through an overflow weir to dewater and output an oversize block clean coal product 2 and undersize water, the heavy product is discharged out of the jigging machine B by oversize discharging and screen-penetrating discharging to enter a tail coal dewatering screen E, dewatering is conducted in the tail coal dewatering screen E and an oversize tail coal product 3 and undersize water are output, the undersize water output by the clean coal dewatering screen D and the tail coal dewatering screen E are fed into a dredging sump F respectively, and the undersize water is separated into circulating water 7 and underflow by the dredging sump F and by precipitation overflowing, wherein the circulating water 7 is used in the separation link, and the underflow is pumped into a tail coal filter press J by a pump for filter pressing; c. the coal material with particle size less than 3 mm is fed from an upper end of a tank body of a TBS C along a tangent line, the coal material with particle size less than 3 mm does interference settling movement in the TBS C and separation is realized according to density, a low-density light product is discharged from the TBS C along with overflow to enter a sieve bend G of 0.5 mm for screening, a high-density product of the TBS C is discharged from a discharging valve at the bottom of the TBS C to enter a tail coal centrifugal machine I, the high-density heavy product is dewatered by the tail coal centrifugal machine I to obtain a tail coal product 5 and centrifugal machine centrifugate a, an oversize material screened by the sieve bend G is fed into a clean coal centrifugal machine H to dewater to obtain a powder clean coal product 4 and centrifugal machine centrifugate b, and the centrifugal machine centrifugate b returns to the TBS C for recycling, wherein a separation density of the TBS C is marked by a vitrinite that the content of less than 1.45g/cm density level accounts for 90%, the vitrinite coal content being 57%, and that the content of greater than 1.45g/cm density level accounts for 10%, the vitrinite content being 57%; and the coal material with particle size greater than 3 mm after separation by the TBS C accounts for 93%, the vitrinite content being 55%, and the coal material with particle size less than 3 mm accounts form 7%, the vitrinite content being 30%; and d. the underflow of the dredging sump, the centrifugal machine centrifugate a and a undersize product of the sieve bend are fed into the tail coal filter press forfilter pressing, and dewatering is conducted to obtain a tail coal slime product with particle size less than 0.5 mm, wherein filtrate serves as the circulating water 7 for recycling, and the tail coal slime product

6 with particle size less than 0.5 mm directly serves as a tail coal product without being

subjected to flotation.

The whole separation process only uses a water medium, without adding a medium

recovering process.

Embodiment:

The coal sample of the used coal-to-liquid raw coal is taken from the clean coal product

of Shendong Group Coal Coal-to-liquid Raw Coal Preparation Plant,. The active components

of the raw coal are mainly concentrated in large fraction, the density of different coal rock

components is quite different. Therefore, effective separation may be realized by a gravity

separation method. Considering that the jigging machine has a wide separation particle size

range and sufficient separation precision and the TBS has good separation effect on coarse

coal slime, the coarse coal slime may be separated by TBS.

According to the separation lower limit of the jigging machine and the separation lower

limit of the TBS, 3 mm classification is adopted, the size fraction of +3 mm accounts for 93%

and the active component content is 56%, and the size fraction of -3 mm accounts for 7% and

the active component content is 30%.

According to a washability curve, the separation density is about 1.45, the density level

of -1.45 accounts for 8% and the active component content is 30%, and the density level of

+1.45 accounts for 92% and the active component content is 5 7 %.

A vibrating screen (sieve pore of 3 mm), a jigging machine, a TBS, a centrifugal

dewatering machine, a clean coal dewatering screen, a tail coal dewatering screen, a dredging

sump, a sieve bend (0.5mm) and a filter press are adopted. Firstly, raw coal 1 is fed into a classifying screen A by a scraper conveyor to perform 3 mm classification, an oversize material is fed into a feeding machine and then is fed into a jigging machine B through the feeding machine, after heavy and light products are layered, the light product enters a clean coal dewatering screen D through an overflow weir, oversize clean coal serves as a block clean coal product 2 after being dewatered, and undersize water enters a dredging sump F; the heavy product on the lower layer is discharged by oversize discharging and screen-penetrating discharging to enter a tail coal dewatering screen E, the tail coal serves as a tail coal product 3 after being dewatered, and undersize water enters the dredging sump F; the dredging sump F overflows to serve as circulating water 7 for the separation link, and the underflow is pumped by a pump into a tail coal filter press J; and after classification is conducted by the classifying screen A, the raw coal of -3 mm is fed from the upper end of a groove body of the TBS C along the tangent line, the materials do interference settling movement in the separator to realize separation according to density, the low-density material is discharged along with overflow and passes through a 0.5 mm sieve bend G, the oversize material directly serves as a powder clean coal product 4 after being dewatered by a clean coal centrifugal machine, centrifugal machine centrifugate returns to the

TBS C, the undersize product of the sieve bend enters the tail coal filter press J, a heavy

product of the TBS C is discharged from a discharging valve at the bottom and serves as a tail

coal product 5 after being dewatered by the tail coal centrifugal machine I, the centrifugal

machine centrifugate enters the tail coal filter press J for filter pressing, and dewatering is

conducted to obtain a tail coal slime product 6 of -0.5 mm, wherein filtrate serves as

circulating water 7.

CLAIMES:

1. A coal-to-liquid raw coal enrichment separation method based on water medium separation, comprising the following steps: a. feeding raw coal (1) into a classifying screen (A) to perform 3 mm classification, so as to obtain two coal materials with particle size greater than 3 mm and particle size less than 3 mm; b. feeding the coal material with particle size greater than 3 mm into a jigging machine (B) to perform separation, after layering heavy and light products in the jigging machine (B), feeding the light product into a clean coal dewatering screen (D) through an overflow weir to dewater and output an oversize block clean coal product (2) and undersize water, discharging the heavy product out of the jigging machine (B) by oversize discharging and screen-penetrating discharging to enter a tail coal dewatering screen (E), dewatering in the tail coal dewatering screen (E) and outputting an oversize tail coal product (3) and undersize water, feeding the undersize water output by the clean coal dewatering screen (D) and the tail coal dewatering screen (E) into a dredging sump (F) respectively, and separating the undersize water into circulating water (7) and underflow by the dredging sump (F) and by precipitation overflowing, wherein the circulating water (7) is used in the separation link, and the underflow is pumped into a tail coal filter press (J) by a pump for filter pressing; c. feeding the coal material with particle size less than 3 mm from an upper end of a tank body of a TBS (C) along a tangent line, enabling the coal material with particle size less than 3 mm to do interference settling movement in the TBS (C) and realize separation according to density, discharging a low-density light product from the TBS (C) along with overflow to enter a sieve bend (G) of 0.5 mm for screening, discharging a high-density product of the TBS (C) from a discharging valve at the bottom of the TBS (C) to enter a tail coal centrifugal machine (I), dewatering the high-density heavy product by the tail coal centrifugal machine (I) to obtain a tail coal product (5) and centrifugal machine centrifugate a, feeding an oversize material screened by the sieve bend (G) into a clean coal centrifugal machine (H) to dewater to obtain a powder clean coal product (4) and centrifugal machine centrifugate b, and

Claims

returning the centrifugal machine centrifugate b to the TBS (C) for recycling; and

d. feeding the underflow of the dredging sump (F), the centrifugate a of the tail coal

centrifugal machine (I) and a undersize product of the sieve bend (G) into the tail coal filter

press (J) for filter pressing, and dewatering to obtain a tail coal slime product (6) with particle

size less than 0.5 mm, wherein filtrate serves as the circulating water (7) for recycling.
2. The coal-to-liquid raw coal enrichment separation method based on water medium

separation according to claim 1, wherein a separation density of the TBS (C) is marked by a

vitrinite that the content of less than 1.45g/cm 3 density level accounts for 90%, the vitrinite

coal content being 57%, and that the content of greater than 1.45g/cm 3 density level accounts

for 10%, the vitrinite content being 5 7 %.
3. The coal-to-liquid raw coal enrichment separation method based on water medium

separation according to claim 1, wherein the coal material with particle size greater than 3

mm after separation by the TBS (C) accounts for 93%, the vitrinite content being 5 5 %; and

the coal material with particle size less than 3 mm accounts form 7%, the vitrinite content

being 30%.
4. The coal-to-liquid raw coal enrichment separation method based on water medium

separation according to claim 1, wherein the whole separation process only uses a water

medium, without adding a medium recovering process.
5. The coal-to-liquid raw coal enrichment separation method based on water medium

separation according to claim 1, wherein the tail coal slime product (6) with particle size less

than 0.5 mm directly serves as a tail coal product without being subjected to flotation.

Coal-to-liquid raw coal

Vibrating screen

Jigging machine TBS

Clean coal dewatering screen Tail coal dewatering screen Sieve bend Tail coal centrifugal machine

Clean coal Dredging sump centrifugal machine Tail coal filter press

Block clean Circulating Tail coal Powder Coal slime Circulating Tail coal coal water clean coal water

FIG. 1

1 / 2

FIG. 2

2 / 2