A raw coal rough separation and fine separation two-stage separation process with high heavy product content

Abstract

The present application provides a raw coal coarse cleaning-precise cleaning two-stage separation process with high heavy product content, comprising the following steps: dry classification of raw coal to obtain screen oversize I and screen undersize I, the screen oversize I is fed into a moving sieve jig for separation to obtain coarse clean coal I and gangue I; the coarse clean coal I is crushed, and the crushed product is mixed with the screen undersize I of step a, and then deslimed to obtain screen oversize II and screen undersize II; the screen oversize II is fed into a cylindrical pressureless two-product dense medium cyclone I for coarse cleaning to obtain coarse clean coal II and gangue II; the screen undersize II is fed into a classification cyclone to obtain underflow and overflow, the underflow is fed into a spiral separator for coarse cleaning to obtain coarse clean coal III and gangue III; the coarse clean coal II and the coarse clean coal III are mixed and fed into a conical pressure two-product dense medium cyclone for precise cleaning to obtain clean coal I and medium coal. The present application has the advantages of simple process, high separation precision, good running stability and suitability for industrial production.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coal separation, in particular to a two-stage separation process of rough separation and fine separation of raw coal with high heavy product content. BACKGROUND

[0002] In the field of coal separation, the proportion of low-density materials in the feed is usually large, and the proportions of medium-density and high-density materials are small. Through washing and separation, a large amount of clean coal can be produced, providing a prerequisite for efficient and clean use of coal and improving the economic benefits of enterprises. However, the occurrence conditions and coal quality of coal resources in China vary greatly. Some coal resources have high heavy product content and low light product content, that is, the proportion of medium-density and high-density materials is large, and the proportion of low-density materials is small. It is difficult to handle using traditional pressurized two-product dense medium cyclone, unpressurized or pressurized three-product dense medium cyclone. For example, a jigging medium coal unpressurized three-product dense medium cyclone re-separation system is disclosed in Chinese patent CN 109821648 B. Because the cone ratio of these three cyclones is a fixed value, the ratio of the underflow and overflow of the cyclone is determined, and it is suitable for feed with more light products and less heavy products. If these three processes are used to handle raw coal with high heavy product content, the underflow port will be blocked. In order to avoid blockage, the size or number of equipment needs to be increased, resulting in a phenomenon of big horse pulling small cart. In addition, when using pressurized dense medium cyclone, the feed is subjected to soaking in heavy medium, stirring and impact by the impeller of the feed pump, and long-distance pipeline transportation, which will produce a large amount of secondary coal slime, and is not suitable for coal quality conditions prone to slurry. SUMMARY

[0003] The present application provides a two-stage separation process of rough separation and fine separation of raw coal with high heavy product content, which is simple, has high separation precision, and is stable in operation, and is suitable for industrial production.

[0004] The technical scheme of the present application is as follows: a two-stage separation process of rough separation and fine separation of raw coal with high heavy product content, comprising the following steps:

[0005] a. Dry classification of raw coal to obtain sieve oversize I and sieve undersize I, and the sieve oversize I is fed into a movable sieve jig to obtain coarse clean coal I and gangue I;

[0006] b. Crushing the coarse clean coal I of step a, and mixing the crushing product with the sieve undersize I of step a, and then desliming to obtain sieve oversize II and sieve undersize II;

[0007] c. Feeding the sieve oversize II of step b into a cylindrical unpressurized two-product dense medium cyclone I for rough separation to obtain coarse clean coal II and gangue II;

[0008] d. The underflow of the step b is fed into a classifying cyclone to obtain an underflow and an overflow, the underflow is fed into a spiral separator to obtain a coarse clean coal III and a gangue III;

[0009] e. The coarse clean coal II of the step c and the coarse clean coal III of the step d are mixed and fed into a conical pressure two-product dense medium cyclone to obtain a clean coal I and a medium coal.

[0010] Further, when the raw coal is coking coal, the following steps are further included:

[0011] f. The overflow of the step d is fed into a flotation machine to obtain a clean coal II and a tail coal, the clean coal II is mixed into the clean coal I of the step e to obtain a clean coal product;

[0012] g. The flotation tail coal of the step f is mixed into the medium coal of the step e to obtain a medium coal product.

[0013] Further, when the raw coal is power coal, the overflow of the step d is mixed into the medium coal of the step e to obtain a medium coal product.

[0014] Further, the gangue II of the step c and the gangue III of the step d are mixed into the gangue I of the step a to obtain a gangue product.

[0015] Further, the particle size of the raw coal of the step a is 300-0 mm.

[0016] Further, the dry classification of the step a adopts an inclined linear vibrating screen, and the screen size is 35 or 50 mm.

[0017] Further, the particle size of the crushing product of the step b is 80-0 or 50-0 mm.

[0018] Further, the desliming of the step b adopts an inclined linear vibrating screen, and the screen gap size is 1, 2 or 3 mm.

[0019] Further, the classification particle size of the classifying cyclone of the step d is 0.25 or 0.5 mm.

[0020] The beneficial effects of the present application are:

[0021] (1) The moving sieve jig is adopted to pre-discharge a large amount of large block heavy products (gangue) with high efficiency and low operation cost, so that the amount of gangue entering the cylindrical pressureless two-product dense medium cyclone is effectively reduced, and the number or type of equipment in the subsequent link is reduced. If a large amount of gangue prone to mudification enters the subsequent dense medium separation link, the following adverse consequences will be caused: the mudification of the gangue causes the instability of the working dense medium properties; the subsequent separation product is difficult to be deslimed, which reduces the desliming effect, increases the number or type of equipment in the desliming link, and increases the medium consumption; the load of the flotation system and the coal slurry system is increased, the flotation effect is deteriorated, and the coal slurry is difficult to be clarified, and the pressure filtration dewatering effect is also reduced.

[0022] (2)Adopting the two-stage separation process of the cylindrical pressureless two-product dense medium cyclone + the conical pressurized two-product dense medium cyclone, when the throughput of the underflow (heavy product) or overflow (light product) of the first stage is large (40%-80% of the feed), normal production can be realized, and two flexible production modes can be realized, i.e., the first stage is roughing and the second stage is cleaning, or the first stage is cleaning and the second stage is scavenging. The first production mode is to discharge gangue in the first stage and to output clean coal and medium coal in the second stage. The second production mode is to output clean coal in the first stage and to output medium coal and gangue in the second stage. The traditional separation process is to adopt the conical pressurized two-product dense medium cyclone in both stages, and only the second production mode can be realized. Moreover, the underflow port of the conical pressurized two-product dense medium cyclone has limited discharge capacity for heavy products, which is about 20% of the feed. In order to meet normal production, the number or type of the dense medium cyclone needs to be greatly increased, which results in the phenomenon of "big horse pulling small cart".

[0023] (3)The moving sieve jig + the cylindrical pressureless two-product dense medium cyclone re-separation process can greatly reduce the amount of secondary slime, which is reduced by one time compared with the traditional conical pressurized two-product dense medium cyclone separation process.

[0024] (4)The 1-0.25mm fine coal roughing link is set, and the spiral separator is used to pre-discharge the high-ash fine gangue in the fine coal, which has the following beneficial effects: The high-ash fine gangue is easy to be slimed, and this part of material is discharged in advance to avoid large fluctuations in the properties of the heavy medium; The amount of slime entering the medium removal link is reduced, which is beneficial to improve the medium removal effect and reduce the medium consumption; The amount of high-ash secondary slime is reduced, the amount of feed entering the flotation system is reduced, the load of the subsequent flotation system and coal slurry system is reduced, the flotation effect is improved, and the efficiency of the coal slurry concentration filter recovery is also improved.

[0025] (5)The spiral separator roughing + the pressurized two-product dense medium cyclone cleaning two-stage process is used to separate fine coal, and the 1-0.25mm coarse clean coal and the 80-1mm coarse clean coal are mixed in the dense medium cyclone and are effectively separated in the cleaning link, which simplifies the process flow.

[0026] (6)The present application is suitable for coking coal and power coal with high heavy product content and easy sliming gangue, and has wide applicability. BRIEF DESCRIPTION OF DRAWINGS

[0027] In order to make the technical solutions in the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some of the embodiments of the present application, and not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0028] Figure 1 A flow chart of the two-stage separation process of high heavy product content raw coal rough separation-clean separation. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, and not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0030] As shown in the figure, a two-stage separation process of high heavy product content raw coal rough separation-clean separation includes the following steps: Figure 1

[0031] a. Dry classification of raw coal to obtain sieve oversize I and sieve undersize I, and the sieve oversize I is fed into a moving sieve jig for separation to obtain rough clean coal I and gangue I; the particle size of the raw coal is 300-0 mm, and the dry classification adopts an inclined linear vibrating screen with a screen size of 35 or 50 mm;

[0032] b. Crushing the rough clean coal I in step a, and mixing the crushing product with the sieve undersize I in step a for desliming to obtain sieve oversize II and sieve undersize II; the particle size of the crushing product is 80-0 or 50-0 mm; the desliming adopts an inclined linear vibrating screen with a screen gap size of 1, 2 or 3 mm;

[0033] c. Feeding the sieve oversize II in step b into a cylindrical pressureless two-product dense medium cyclone I for rough separation to obtain rough clean coal II and gangue II;

[0034] d. Feeding the sieve undersize II in step b into a classification cyclone to obtain underflow and overflow, and feeding the underflow into a spiral separator for rough separation to obtain rough clean coal III and gangue III; the classification particle size of the classification cyclone is 0.25 or 0.5 mm;

[0035] e. Mixing the rough clean coal II in step c and the rough clean coal III in step d, and feeding the mixture into a conical pressure two-product dense medium cyclone for clean separation to obtain clean coal I and medium coal.

[0036] Mixing the gangue II in step c and the gangue III in step d into the gangue I in step a to obtain a gangue product. ​

[0037] When the raw coal is coking coal, the process further comprises the following steps:

[0038] f. feeding the overflow of step d into a flotation machine for flotation to obtain clean coal II and tailings, and mixing the clean coal II into the clean coal I of step e to obtain a clean coal product;

[0039] g. mixing the flotation tailings of step f into the middlings of step e to obtain a middlings product.

[0040] When the raw coal is power coal, the overflow of step d is mixed into the middlings of step e to obtain a middlings product.

[0041] The specific implementation is as follows:

[0042] Taking a coking coal preparation plant with a scale of 2 million tons / year as an example, a two-stage separation process with high content of heavy products includes the following steps:

[0043] a. using 1 banana screen (model ABS30x48, screen hole 35 mm) to dry classify 300-0 mm raw coal to obtain 300-35 mm screen oversize and 35-0 mm screen undersize, and feeding the 300-35 mm screen oversize into 1 moving sieve jig (model YWT1 / 2.2) for separation to obtain 300-35 mm clean coal and 300-35 mm gangue;

[0044] b. crushing the 300-35 mm clean coal of step a to less than 80 mm, mixing the 80-0 mm crushed product with the 35-0 mm screen undersize of step a, and using 2 banana screens (model ABS30x73, screen gap 1 mm) for desliming to obtain 80-1 mm screen oversize and 1-0 mm screen undersize;

[0045] c. feeding the 80-1 mm screen oversize of step b into 2 cylindrical pressureless two-product dense medium cyclones (model NWZX1000) for rough separation to obtain 80-1 mm clean coal and 80-1 mm gangue;

[0046] d. feeding the 1-0 mm screen undersize of step b into 1 set of classification cyclones (model NNX500x4) to obtain 1-0.25 mm underflow and 0.25-0 mm overflow, and feeding the 1-0.25 mm underflow into 1 set of spiral separators (6 columns, 3 heads per column, φ1000) for rough separation to obtain 1-0.25 mm clean coal and 1-0.25 mm gangue;

[0047] e. mixing the 80-1 mm clean coal of step c and the 1-0.25 mm clean coal of step d and feeding into 1 conical pressure two-product dense medium cyclone (model φ1200) for cleaning to obtain 80-0.25 mm clean coal and 80-0.25 mm middlings;

[0048] f. Feed the 0.25-0mm overflow from step d into a flotation machine (model XJM-S12, 4 cells) for flotation to obtain 0.25-0mm clean coal and 0.25-0mm tailings. Mix the 0.25-0mm clean coal with the 80-0.25mm clean coal from step e to obtain 80-0mm clean coal product.

[0049] g. The 0.25-0mm tailings from step f are mixed with the 80-0.25mm middlings from step e to obtain the 80-0mm middlings product.

[0050] In addition, the 80-1mm gangue from step c and the 1-0.25mm gangue from step d are mixed with the 300-35mm gangue from step a to obtain the gangue product.

[0051] The coal preparation product balance is shown in Table 1. The raw coal has a high ash content of 32.89%, and should be processed across all particle sizes to reduce ash and improve quality. After processing using this separation process, the ash content of the clean coal is controlled below 10%, effectively reducing ash content and meeting production requirements.

[0052] Table 1. Coal Preparation Product Balance Sheet

[0053]

[0054]

[0055] For a coal preparation plant with a capacity of 2 million tons / year, the separation process of this invention can save two φ1000 pressureless feed three-product heavy medium cyclones, as well as supporting product collection boxes, qualified medium tanks, pumps, pipelines, electrical equipment, etc. The equipment cost is approximately RMB 2.2 million, and the civil engineering and installation costs are saved by approximately RMB 1.48 million, for a total saving of approximately RMB 3.68 million in project investment.

[0056] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A two-stage separation process for raw coal with high heavy product content, characterized in that, Includes the following steps: a. The raw coal is dry-graded to obtain oversize material I and undersize material I. Oversize material I is then fed into a jigging machine for separation to obtain coarse clean coal I and gangue I. b. Crush the coarse coal I obtained in step a, mix the crushed product with the undersize I obtained in step a, and then deslim it to obtain the oversize II and undersize II. c. Feed the sieve material II from step b into a cylindrical pressureless two-product heavy medium hydrocyclone I for coarse separation to obtain coarse clean coal II and gangue II; d. Feed the undersize material II from step b into a classifying hydrocyclone to obtain underflow and overflow. The underflow enters a spiral separator for coarse separation to obtain coarse clean coal III and gangue III. e. The coarse coal II from step c and the coarse coal III from step d are mixed and fed into a conical pressurized two-product heavy medium cyclone for fine selection to obtain clean coal I and middlings; The raw coal particle size in step a is 300-0 mm; the dry grading in step a uses an inclined linear vibrating screen with a screen aperture size of 35 or 50 mm. The particle size of the crushed product in step b is 80-0 or 50-0 mm; the desliming in step b is performed using an inclined linear vibrating screen with a screen opening size of 1, 2 or 3 mm. The classifying particle size of the hydrocyclone in step d is 0.25 or 0.5 mm; The gangue II from step c and the gangue III from step d are mixed into the gangue I from step a to obtain the gangue product. When the raw coal is coking coal, the following steps are also included: f. Feed the overflow from step d into a flotation machine for flotation to obtain clean coal II and tailings. Mix clean coal II with clean coal I from step e to obtain clean coal product. The ash content of the clean coal is controlled below 10%. g. The flotation tailings from step f are mixed with the middlings from step e to obtain the middlings product.

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