High-pressure roller grinding closed-circuit screening preselection method and device

Abstract

The present invention provides a method and device for pre-selection by closed-circuit screening of a high-pressure roller mill, comprising the following steps: dividing the discharge of the high-pressure roller mill into central material and edge material according to a preset ratio; screening the central material by a wet screening process and screening the edge material by a dry screening process; returning the materials on the screen in the wet screening process and the materials on the screen in the dry screening process to the high-pressure roller mill; for the materials under the screen in the wet screening process, using a wet pre-magnetic separator for separation to obtain wet pre-selected concentrate; for the materials under the screen in the dry screening process, using a magnetic reversal dry separator for separation to obtain dry-selected concentrate. By using the present invention, problems existing in the prior art can be solved, such as high moisture content on the screen in the production site, serious adhesive phenomenon on the return belt, seriously affecting production operation, and easily causing serious wear of equipment, etc.

Description

Technical Field

[0001] The present invention relates to the technical field of ore dressing, and more specifically, to a method and device for pre-selection of closed-circuit screening of a high-pressure roller mill. Background Art

[0002] Most iron ores in China are "poor, miscellaneous, and fine", and pre-tailing operations are often required before grinding. The conventional treatment process is three-stage one-closed-circuit crushing and dry separation. In recent years, great progress has been made in ore dressing equipment, and many high-efficiency and energy-saving equipment have been maturely applied. The high-pressure roller mill is a typical representative. After being introduced from the cement industry to the iron ore industry and undergoing a large number of practical improvements, the high-pressure roller mill has gradually replaced the traditional three-stage one-closed-circuit process, reducing the feed particle size of the ball mill from 12 mm to 3 mm, with remarkable energy-saving effects. Moreover, a 3-mm particle size can already be used for large-particle-size wet magnetic separation operations to pre-throw tailings in advance, and the effect is better than that of dry magnetic separation.

[0003] However, a large amount of water needs to be added in the production of large-particle-size wet magnetic separation. In the production, the closed-circuit screening of the high-pressure roller mill is combined with 3-mm wet magnetic separation. At the same time, due to the relatively fine feed particle size of the screening, in order to ensure the screening efficiency, wet screening operations are mostly used. The moisture content on the screen in most production sites is as high as more than 10%, and the phenomenon of sticky material on the return belt is serious, which also affects the moisture content of the material fed into the high-pressure roller mill, seriously affecting the production operation. At the same time, in the production of large-particle-size wet magnetic separation, due to the large feed particle size, the wear is often relatively serious. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a method and device for pre-selection of closed-circuit screening of a high-pressure roller mill to solve the problems in the current process of combining the closed-circuit screening of a high-pressure roller mill with wet magnetic separation, such as the high moisture content on the screen in the production site, resulting in serious sticky material on the return belt; at the same time, it affects the moisture content of the material fed into the high-pressure roller mill, resulting in serious impact on the production operation; and in the production of large-particle-size wet magnetic separation, due to the large feed particle size, the equipment wear is serious, etc.

[0005] The present invention provides a method for pre-selection of closed-circuit screening of a high-pressure roller mill, including the following steps:

[0006] Dividing the discharge of the high-pressure roller mill into central material and edge material according to a preset ratio;

[0007] For the central material, a wet screening process is used for screening, and for the edge material, a dry screening process is used for screening;

[0008] Returning the materials on the screen in the wet screening process and the materials on the screen in the dry screening process to the high-pressure roller mill. For the materials under the screen in the wet screening process, a wet pre-magnetic separator is used for separation to obtain wet pre-concentrate; for the materials under the screen in the dry screening process, a magnetic reversal dry separator is used for separation to obtain dry-concentrate;

[0009] Both the ball-milled dry-concentrate obtained by ball-milling the dry-concentrate and the wet pre-concentrate are fed into a classification pre-separation process for separation.

[0010] In addition, a preferred solution is that the discharge of the high-pressure roller mill is divided into central material and edge material according to a preset ratio, which includes:

[0011] The raw ore is ground by the high-pressure roller mill to obtain the discharge of the high-pressure roller mill;

[0012] According to the preset ratio, the discharge of the high-pressure roller mill is adjusted and divided into raw materials through an adjustable material distribution funnel to obtain central material and edge material.

[0013] In addition, a preferred solution is that in the wet screening process, a straight vibrating screen is used to screen the central material; wherein, the screen hole size of the straight vibrating screen is 1 mm - 2 mm.

[0014] In addition, a preferred solution is that in the dry screening process, a dry fine powder screen is used to screen the edge material; wherein, the screen hole size of the dry fine powder screen is 3 mm - 5 mm.

[0015] In addition, a preferred solution is that in the process of returning the oversize materials in the wet screening process and the oversize materials in the dry screening process back to the high-pressure roller mill,

[0016] The oversize materials in the wet screening process and the oversize materials in the dry screening process are returned to the high-pressure roller mill through the same preset return material belt conveyor.

[0017] In addition, a preferred solution is that in the process of separating the undersize materials in the wet screening process by using a wet pre-magnetic separator to obtain wet pre-concentrate, and separating the undersize materials in the dry screening process by using a magnetic inversion dry separator to obtain dry-concentrate,

[0018] Both the wet tailings obtained by separation using the wet pre-magnetic separator and the dry tailings obtained by separation using the magnetic inversion dry separator are subjected to tailing rejection treatment according to a preset tailing rejection index.

[0019] In addition, a preferred solution is that the ball-milled dry-concentrate obtained by ball-milling the dry-concentrate and the wet pre-concentrate are fed into a classification pre-separation process for separation, which includes:

[0020] The dry-concentrate is ball-milled by a ball mill to obtain ball-milled dry-concentrate;

[0021] Feed the ball-milled dry-preselected concentrate and the wet-preselected concentrate into the classification preselection treatment process for separation treatment.

[0022] The high-pressure roll grinding closed-circuit screening device for the high-pressure roll grinding closed-circuit screening preselection method as described above provided by the present invention includes a high-pressure roll mill, a material distribution and adjustment device, a screening device, a separation device, a ball milling device, and a classification preselection device; wherein,

[0023] The material distribution and adjustment device includes a feed inlet, a central material outlet, and a side material outlet;

[0024] The screening device includes a wet screening device and a dry screening device;

[0025] The separation device includes a wet pre-magnetic separator and a magnetic reversal dry separator;

[0026] The discharge port of the high-pressure roll mill is connected to the feed inlet of the material distribution and adjustment device; the central material outlet of the material distribution and adjustment device is connected to the feed end of the wet screening device, and the side material outlet of the material distribution and adjustment device is connected to the feed end of the dry screening device; the under-screen discharge port of the wet screening device is connected to the wet pre-magnetic separator; the under-screen discharge port of the dry screening device is connected to the magnetic reversal dry separator; the over-screen discharge ports of the wet screening device and the dry screening device are both connected to the feed inlet of the high-pressure roll mill; the discharge port of the magnetic reversal dry separator is connected to the ball milling device, and the discharge ports of the ball milling device and the wet pre-magnetic separator are both connected to the classification preselection device.

[0027] In addition, preferably, the material distribution and adjustment device is an adjustable material distribution funnel; and / or, the wet screening device is a linear vibrating screen; and / or, the dry screening device is a dry fine powder screen; and / or, the ball milling device is a ball mill.

[0028] In addition, preferably, the over-screen discharge ports of the wet screening device and the dry screening device are connected to the feed inlet of the high-pressure roll mill through the same return conveyor belt.

[0029] As can be seen from the above technical solution, the high-pressure roll grinding closed-circuit screening pre-selection method and device provided by the present invention grind the raw ore through a high-pressure roll mill, and the discharged material is adjusted into central material and edge material according to a preset ratio according to raw materials of different properties. Due to the working principle of the high-pressure roll mill, the central material is much finer than the edge material. Therefore, aiming at this characteristic, the central material and the edge material are processed separately. Among them, since the central material has a large content of fine particles, a wet screening process can be adopted, and the screened product enters the wet pre-magnetic separation operation. Due to the fine particle size, the problem of wear in wet magnetic separation of large particle sizes is solved; the edge material has a coarser particle size and adopts a dry screening process, and the screened product particle size uses a magnetic reversal dry separator, which ensures the pre-selection effect and also meets the requirement of the magnetic reversal dry separator for uniform feeding particle size. The two screened products are returned to the high-pressure roll mill. At this time, the comprehensive moisture content is reduced to less than 5%, which ensures the conveying operation and solves the problem of high moisture content. The classification screening gives full play to the characteristics of wet screening and dry screening, reduces the influence of uneven material particle size, improves the screening efficiency, and reduces the cycle compliance. After the dry concentrate is ground, the wet pre-selected concentrate and the dry pre-selected concentrate both undergo a classification pre-selection process, which makes full use of the characteristics of the mineral particle size composition and reduces the energy consumption of the grinding system.

[0030] To achieve the above and related purposes, one or more aspects of the present invention include the features that will be described in detail later. The following description and the accompanying drawings illustrate certain exemplary aspects of the present invention in detail. However, these aspects only indicate some of the various ways in which the principles of the present invention can be used. In addition, the present invention aims to include all these aspects and their equivalents. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] By referring to the following description in conjunction with the accompanying drawings, and with a more comprehensive understanding of the present invention, other objects and results of the present invention will become more apparent and easier to understand. In the drawings:

[0032] Figure 1 is a flowchart of the high-pressure roll grinding closed-circuit screening pre-selection method according to an embodiment of the present invention;

[0033] Figure 2 is a process diagram of the high-pressure roll grinding closed-circuit screening pre-selection method according to an embodiment of the present invention;

[0034] Figure 3 is a structural schematic diagram of the high-pressure roll grinding closed-circuit screening pre-selection device according to an embodiment of the present invention;

[0035] In the drawings, 1 - high-pressure roll mill, 2 - material adjustment device, 3 - wet pre-magnetic separator, 4 - magnetic reversal dry separator, 5 - ball mill device, 6 - cyclone, 7 - classification pre-selection device, 8 - wet screening device, 9 - dry screening device.

[0036] In all the drawings, the same reference numerals indicate similar or corresponding features or functions. Detailed implementation manners

[0037] In the following description, for purposes of explanation, in order to provide a thorough understanding of one or more embodiments, numerous specific details are set forth. However, it is apparent that the embodiments can be practiced without these specific details.

[0038] Aiming at the problems in the current process of closed-circuit screening of a high-pressure roller mill in combination with wet magnetic separation as mentioned above, such as high moisture content on the screen in the production site, which leads to serious material sticking on the return belt; at the same time, it affects the moisture content of the material fed into the high-pressure roller mill, resulting in serious impact on production operation; and in the production, due to the large feed particle size of the large-particle wet magnetic separation, the equipment wear is serious, etc., a high-pressure roller mill closed-circuit screening preselection method and device are proposed.

[0039] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0040] In order to illustrate the high-pressure roller mill closed-circuit screening preselection method and device provided by the present invention, Figure 1 shows the flow of the high-pressure roller mill closed-circuit screening preselection method according to an embodiment of the present invention; Figure 2 shows the process of the high-pressure roller mill closed-circuit screening preselection method according to an embodiment of the present invention; Figure 3 shows the structure of the high-pressure roller mill closed-circuit screening preselection device according to an embodiment of the present invention.

[0041] As Figures 1 to 3 collectively shown, the high-pressure roller mill closed-circuit screening preselection method provided by the present invention includes the following steps:

[0042] S1. Divide the discharge of the high-pressure roller mill 1 into central material and edge material according to a preset ratio;

[0043] S2. For the central material, adopt a wet screening process for screening, and for the edge material, adopt a dry screening process for screening;

[0044] S3. Return the materials on the screen in the wet screening process and the materials on the screen in the dry screening process to the high-pressure roller mill 1. For the materials under the screen in the wet screening process, use a wet pre-magnetic separator 3 for separation to obtain wet pre-selected concentrate; for the materials under the screen in the dry screening process, use a magnetic inversion dry separator 4 for separation to obtain dry-selection concentrate;

[0045] S4. Feed the ball-milled dry-selection concentrate obtained after ball-milling the dry-selection concentrate and the wet pre-selected concentrate into a classification preselection treatment process for separation.

[0046] The raw ore is ground by a high-pressure roller mill 1, and its discharge is adjusted and divided into central material and edge material according to a preset ratio according to the raw materials of different properties. Due to the working principle of the high-pressure roller mill 1, the central material is much finer than the edge material. Therefore, aiming at this characteristic, the central material and the edge material are processed separately. Among them, since the central material has a large content of fine particles, a wet screening process can be adopted, and the undersize product enters the wet pre-magnetic separation operation. Due to the fine particle size, the problem of wear in wet magnetic separation of large particle sizes is solved; the edge material has a coarser particle size and adopts a dry screening process, and the magnetic reversal dry separator 4 is used for the undersize product, which ensures the pre-selection effect and also meets the requirement of the magnetic reversal dry separator 4 for uniform feed particle size. The two oversize products are returned to the high-pressure roller mill 1. At this time, the comprehensive moisture content is reduced to less than 5%, which ensures the conveying operation and solves the problem of high moisture content. The classification screening gives full play to the characteristics of wet screening and dry screening, reduces the influence of uneven material particle size, improves the screening efficiency, and reduces the cycle compliance. After the dry concentrate is ground, both the wet pre-selected concentrate and the dry pre-selected concentrate are subjected to a classification pre-selection process, which makes full use of the characteristics of the mineral particle size composition and reduces the energy consumption of the grinding system

[0047] As a preferred embodiment of the present invention, the discharge of the high-pressure roller mill 1 is adjusted and divided into central material and edge material according to a preset ratio, including:

[0048] The raw ore is ground by the high-pressure roller mill 1 to obtain the discharge of the high-pressure roller mill 1;

[0049] According to a preset ratio, the discharge of the high-pressure roller mill 1 is adjusted and divided by an adjustable material distribution funnel to obtain central material and edge material.

[0050] The adjustable material distribution funnel can set the ratio of the central material to the edge material according to the raw materials of different properties, and divide the discharge of the high-pressure roller mill 1 into the central material with finer particle size and the edge material with coarser particle size, which is convenient for subsequent separate treatment.

[0051] As a preferred embodiment of the present invention, in the wet screening process, a linear vibrating screen is used to screen the central material; wherein, the screen hole size of the linear vibrating screen is 1 mm - 2 mm. The wet screening process of the central material can be realized by the linear vibrating screen.

[0052] As a preferred embodiment of the present invention, in the dry screening process, a dry micropowder screen is used to screen the edge material; wherein, the screen hole size of the dry micropowder screen is 3 mm - 5 mm. The dry screening process of the edge material can be realized by the dry micropowder screen.

[0053] As a preferred embodiment of the present invention, in the process of returning both the oversize material in the wet screening process and the oversize material in the dry screening process to the high-pressure roller mill 1,

[0054] The materials on the screen in the wet screening process and the materials on the screen in the dry screening process are returned to the high-pressure roller mill 1 through the same preset return belt conveyor. It can comprehensively adjust the material moisture, reduce the comprehensive moisture to less than 6%, and ensure the conveying effect and the moisture of the feed material for the high-pressure roller mill.

[0055] As a preferred embodiment of the present invention, in the process of separating the materials under the screen in the wet screening process with a wet pre-magnetic separator 3 to obtain wet pre-selected concentrates, and separating the materials under the screen in the dry screening process with a magnetic inversion dry separator 4 to obtain dry-selection concentrates,

[0056] The wet tailings obtained by separating with the wet pre-magnetic separator 3 and the dry tailings obtained by separating with the magnetic inversion dry separator 4 are both subjected to tailing rejection treatment according to the preset tailing rejection index. Among them, the preset tailing rejection index is set according to the iron grade.

[0057] As a preferred embodiment of the present invention, the ball-milled dry-selection concentrates obtained after ball-milling the dry-selection concentrates and the wet pre-selected concentrates are both fed into the classification pre-selection treatment process for separation, including:

[0058] The dry-selection concentrates are ball-milled by a ball mill to obtain ball-milled dry-selection concentrates;

[0059] The ball-milled dry-selection concentrates and the wet pre-selected concentrates are both fed into the classification pre-selection treatment process for separation. Among them, the wet pre-selected concentrates and the ball-milled dry-selection concentrates can be fed into the classification pre-selection treatment process together through a hydrocyclone 6.

[0060] The high-pressure roller mill closed-circuit screening device for the high-pressure roller mill closed-circuit screening pre-selection method provided by the present invention includes a high-pressure roller mill 1, a material distribution and adjustment device 2, a screening device, a separation device, a ball mill device 5, and a classification pre-selection device 7; among them,

[0061] The material distribution and adjustment device 2 includes a feed inlet, a central material outlet, and a side material outlet;

[0062] The screening device includes a wet screening device 8 and a dry screening device 9;

[0063] The separation device includes a wet pre-magnetic separator 3 and a magnetic inversion dry separator 4;

[0064] The discharge port of the high-pressure roller mill 1 is connected to the feed port of the material distribution device 2; the central material outlet of the material distribution device 2 is connected to the feed end of the wet screening device 8, and the side material outlet of the material distribution device 2 is connected to the feed end of the dry screening device 9; the under-screen discharge port of the wet screening device 8 is connected to the wet pre-magnetic separator 3; the under-screen discharge port of the dry screening device 9 is connected to the magnetic inversion dry separator 4; the over-screen discharge ports of both the wet screening device 8 and the dry screening device 9 are connected to the feed port of the high-pressure roller mill 1; the discharge port of the magnetic inversion dry separator 4 is connected to the ball mill device 5, and the discharge ports of both the ball mill device 5 and the wet pre-magnetic separator 3 are connected to the classification preselection device 7.

[0065] As a preferred embodiment of the present invention, the material distribution device 2 is an adjustable material distribution funnel; and / or, the wet screening device 8 is a linear vibrating screen; and / or, the dry screening device 9 is a dry fine powder screen; and / or, the ball mill device 5 is a ball mill.

[0066] As a preferred embodiment of the present invention, the over-screen discharge ports of both the wet screening device 8 and the dry screening device 9 are connected to the feed port of the high-pressure roller mill 1 through the same return conveyor belt.

[0067] In order to better describe and illustrate the high-pressure roller grinding closed-circuit screening preselection method provided by the present invention, the following specific embodiments are provided.

[0068] Comparative Example 1

[0069] The production site in this embodiment is a magnetite ore dressing plant in Hebei, and the preselection process adopted.

[0070] After the high-pressure roller mill processes the incoming material, it undergoes a 3-mm wet closed-circuit screening process. The over-screen material is returned to the high-pressure roller mill, and the under-screen 3-mm material is fed into the large-particle wet pre-magnetic separation for tailing removal. The concentrate is fed into a first-stage ball mill closed-circuit system. During production, the moisture content of the over-screen material in the 3-mm wet screening is high, the circulating load is large, and the pipelines, pumps, and equipment in the 3-mm wet pre-magnetic separation operation are severely worn.

[0071] Example 1

[0072] The embodiment provided by the present invention is to use an adjustable material dividing funnel to divide the material discharged from the high-pressure roller mill 1 into the center material and the side material in view of the large difference in particle size between the center material and the side material of the high-pressure roller mill 1. At the same time, the adjustable material dividing funnel can adjust the center and side materials and the proportion through the built-in regulating valve to adapt to raw materials of different properties. Since the center material has a large content of fine particles, a 1mm linear vibrating screen is used for wet screening; the side material has a coarse particle size and a 4mm dry large micro powder screen is used for dry screening. The sieve hole is set to 4mm to solve the problem of low screening efficiency of 3mm dry screening. Through the above two targeted screenings, the particle size of the materials fed to the two screens is more uniform than that of the full-grade feeding, so the screening efficiency is improved, the circulation load is reduced by 20%, and the working pressure of the high-pressure roller mill 1 is reduced. The two screened products are combined and returned to the high pressure roller mill 1. Since 60% of the ore is dry screened, the comprehensive moisture content of the returned material is reduced from the original 10% to less than 5%, solving the problem of high moisture content, poor environmental protection and difficult transportation.

[0073] In view of the difference in moisture and particle size of the two types of under-screen materials, targeted pre-selection processes are adopted. The 1mm wet screening under-screen material adopts a large-size pre-magnetic separator. Since the particle size is uniform and less than 1mm, the selection effect is good, and the problem of wear on the pre-selection system is also solved at the same time. The particle size of the 4mm dry screening under-screen product is 4mm, and a magnetic reversal dry separator is used. The dry selection effect of the magnetic reversal magnetic separator for this uniform particle size is very good. At the same time, the material can be transported by a belt conveyor to solve the problem of wear when transporting 3mm slurry. At the same time, the 1mm wet pre-selected concentrate is fed into the first-stage grinding cyclone 8 for classification first, and the 4mm dry selection concentrate is fed into the first-stage grinding mill for grinding first, which makes full use of the characteristics of the mineral particle size composition. Combining the two pre-selection processes, the final tailings index is under the same condition (determined according to the iron grade). The first-stage grinding cycle load is reduced from 200% to below 150%, which reduces the energy consumption of the first-stage grinding system, and the energy-saving effect is obvious. At the same time, although the tailings volume is the same, the dry tailings in the present invention account for 40% of the total tailings. This part does not need to enter the tailings pond and can be sold as building materials, with significant benefits.

[0074] As can be seen from the above specific embodiments, for the high-pressure roll grinding closed-circuit screening pre-selection method and device provided by the present invention, the raw ore is ground by a high-pressure roll mill, and its discharge is divided into central material and edge material according to a preset ratio according to raw materials of different properties. Due to the working principle of the high-pressure roll mill, the central material is much finer than the edge material. Therefore, aiming at this characteristic, the central material and the edge material are processed separately. Among them, since the central material has a large content of fine particles, a wet screening process can be adopted, and the screened product enters the wet pre-magnetic separation operation. Since the particle size is fine, the problem of wear in large-particle-size wet magnetic separation is solved; the edge material has a coarser particle size and a dry screening process is adopted, and the screened product particle size uses a magnetic reversal dry separator, which ensures the pre-selection effect and also meets the requirement of the magnetic reversal dry separator for uniform feed particle size. The two screened products are returned to the high-pressure roll mill. At this time, the comprehensive moisture content is reduced to less than 5%, which ensures the conveying operation and solves the problem of high moisture content. The classified screening gives full play to the characteristics of wet screening and dry screening, reduces the influence of uneven material particle size, improves the screening efficiency, and reduces the cycle compliance. After the dry concentrate is ground, the wet pre-selected concentrate both undergoes a classification pre-selection process, which makes full use of the characteristics of the mineral particle size composition and reduces the energy consumption of the grinding system.

[0075] As described above by way of example with reference to the drawings, the high-pressure roll grinding closed-circuit screening pre-selection method and device proposed according to the present invention are described. However, those skilled in the art should understand that various improvements can be made to the above high-pressure roll grinding closed-circuit screening pre-selection method and device proposed by the present invention without departing from the content of the present invention. Therefore, the protection scope of the present invention should be determined by the content of the appended claims.

Claims

1. A closed-circuit screening pre-selection method for high-pressure roller grinding, characterized in that, The steps include: The discharge of the high pressure roller mill is divided into the center material and the side material according to the preset ratio; The center material is screened by a wet screening process, and the side material is screened by a dry screening process; The materials on the screen in the wet screening process and the materials on the screen in the dry screening process are returned to the high-pressure roller mill, and the materials under the screen in the wet screening process are sorted by a wet pre-magnetic separator to obtain a wet pre-selected concentrate; the materials under the screen in the dry screening process are sorted by a magnetic reversing dry separator to obtain a dry-selected concentrate; The ball-milled dry-selected concentrate obtained by ball-milling the dry-selected concentrate and the wet pre-selected concentrate are both sent to a classification pre-selection process for separation.

2. The high-pressure roll grinding closed-circuit screening preselection method according to claim 1, wherein The step of dividing the discharge of the high pressure roller mill into the center material and the side material according to a preset ratio comprises: Grinding the raw ore through the high pressure roller mill to obtain discharge material of the high pressure roller mill; According to a preset ratio, the raw materials discharged from the high pressure roller mill are adjusted and divided through an adjustable material dividing funnel to obtain a center material and a side material.

3. The high-pressure roll grinding closed-circuit screening preselection method according to claim 1, characterized in that In the wet screening process, The center material is screened by a linear vibrating screen, wherein the mesh size of the linear vibrating screen is 1 mm-2 mm.

4. The high-pressure roll grinding closed-circuit screening preselection method according to claim 1, wherein In the dry screening process, The side material is screened using a dry micro-powder sieve; wherein the sieve hole size of the dry micro-powder sieve is 3 mm-5 mm.

5. The high-pressure roll grinding closed-circuit screening preselection method according to claim 1, wherein In the process of returning the material on the screen in the wet screening process and the material on the screen in the dry screening process to the high pressure roller mill, The material on the screen in the wet screening process and the material on the screen in the dry screening process are returned to the high-pressure roller mill through the same preset return belt conveyor.

6. The high-pressure roll grinding closed-circuit screening preselection method according to claim 1, wherein In the process of using a wet pre-magnetic separator to select the under-screened material in the wet screening process to obtain a wet pre-selected concentrate; and using a magnetic reversing dry separator to select the under-screened material in the dry screening process to obtain a dry-selected concentrate, The wet tailings obtained by separation using the wet pre-magnetic separator and the dry tailings obtained by separation using the magnetic reversal dry separator are both disposed of according to preset tailings disposal indicators.

7. The high-pressure roll grinding closed-circuit screening preselection method according to claim 1, characterized in that The ball-milled dry-selected concentrate obtained by ball-milling the dry-selected concentrate and the wet pre-selected concentrate are both sent to a classification pre-selection process for selection, which includes: The dry-selected ore concentrate is subjected to ball milling treatment in a ball mill to obtain a ball-milled dry-selected ore concentrate; The ball-milled dry-selected concentrate and the wet pre-selected concentrate are both sent to the grading pre-selection process for separation treatment.

8. A high-pressure roller grinding closed-circuit screening device for the high-pressure roller grinding closed-circuit screening preselection method according to any one of claims 1-7, characterized in that, It includes a high-pressure roller mill, a material adjustment device, a screening device, a sorting device, a ball mill and a grading pre-selection device; wherein, The material distribution device comprises a feed inlet, a center material outlet and a side material outlet; The screening device includes a wet screening device and a dry screening device; wherein the wet screening device is a linear vibrating screen; The separation device includes a wet pre-magnetic separator and a magnetic reversal dry separator; The discharge port of the high-pressure roller mill is connected to the feed port of the material distribution device; the central material outlet of the material distribution device is connected to the feed end of the wet screening device, and the side material outlet of the material distribution device is connected to the feed end of the dry screening device; the under-screen discharge port of the wet screening device is connected to the wet pre-magnetic separator; the under-screen discharge port of the dry screening device is connected to the magnetic flipping dry separator; the over-screen discharge ports of both the wet screening device and the dry screening device are connected to the feed port of the high-pressure roller mill; the discharge port of the magnetic flipping dry separator is connected to the ball milling device, and the discharge ports of both the ball milling device and the wet pre-magnetic separator are connected to the classification preselection device; The over-screen discharge ports of both the wet screening device and the dry screening device are connected to the feed port of the high-pressure roller mill through the same return conveyor belt.

9. The high-pressure roller mill closed-circuit screening device according to claim 8, wherein, the material distribution device is an adjustable material distribution funnel; and / or, the dry screening device is a dry fine powder sieve; and / or, the ball milling device is a ball mill.

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