A method for separating copper-molybdenum concentrate by gravity separation and classification optimization and magnetic separation

Abstract

The invention discloses a method for separating copper-molybdenum concentrate by gravity separation and classification optimization and magnetic separation, which belongs to the technical field of nonferrous metal beneficiation, and comprises the following steps: slurry gravity separation, screening and classification, coarse-grain strong magnetic roughing, coarse-grain strong magnetic sweeping, fine-grain strong magnetic roughing, fine-grain strong magnetic concentration, fine-grain strong magnetic sweeping, and solid-liquid separation. The invention adopts a physical beneficiation method, selects reasonable slurry gravity separation, screening and classification, coarse-grain strong magnetic roughing, coarse-grain strong magnetic sweeping, fine-grain strong magnetic roughing, fine-grain strong magnetic concentration, fine-grain strong magnetic sweeping, and solid-liquid separation and other combined beneficiation process flows, effectively solves the technical problems existing in conventional copper-molybdenum concentrate separation processes such as poor separation effect, high metal loss, low concentrate quality, large reagent dosage, long process flow, high production cost, multiple pollution sources, and high environmental pressure, improves the beneficiation index and recovery rate of valuable minerals, and each operation section is green and environmentally friendly, and is suitable for large-scale production and application.

Description

Technical Field

[0001] The invention relates to the technical field of nonferrous metal beneficiation, and in particular to a method for separating copper-molybdenum concentrate by gravity separation, classification and optimization and magnetic separation. Background Art

[0002] my country's molybdenum ore reserves are among the highest in the world. The main molybdenum mineral with industrial value is molybdenite, which is often accompanied by pyrite, magnetite, chalcopyrite, galena, sphalerite, arsenopyrite, cassiterite, apatite, quartz, feldspar, calcite and other minerals. Metallic molybdenum has the characteristics of high melting point, high strength, corrosion resistance and abrasion resistance. It is widely used in the metallurgical industry to produce various high-performance alloy steels and has high strategic value.

[0003] Molybdenite has good natural floatability, and hydrocarbon oils such as diesel and kerosene are often used as collectors for flotation recovery. For minerals associated with molybdenite, such as chalcopyrite, pyrite, galena, and scheelite, flotation separation operations usually use a mixed flotation method to produce a mixed rough concentrate, and then add corresponding inhibitors and collectors for flotation separation, thereby obtaining qualified molybdenum concentrate, copper concentrate, tungsten concentrate and other industrial products. Since the valuable mineral associated with molybdenite is mainly chalcopyrite, when the copper-molybdenum mixed concentrate produced by the mixed flotation process is separated by the copper suppression and molybdenum flotation process, the mineral surface will contain a large amount of flotation agents such as hydrocarbon oil, frother and xanthate, and the fine-grained chalcopyrite with good floatability is difficult to be suppressed, resulting in excessive copper in the molybdenum concentrate (i.e., copper-molybdenum concentrate), affecting the quality of the molybdenum product and causing a loss of copper metal.

[0004] In response to the problem of excessive copper content in molybdenum concentrate, mineral processing technicians have done a lot of research work, such as using new reagents for flotation separation, using grinding, ultrasound, and activated carbon to remove the reagents and then flotation separation, using strong magnetic separation technology after removal of the reagent, using roasting and deoiling and then strong magnetic separation technology, using strong oxidants and various inhibitors, etc., all of which can achieve better copper-molybdenum separation effects; however, these separation processes often have technical difficulties and shortcomings such as complicated processes, excessive reagents, serious wastewater and exhaust gas pollution, excessively high production costs, low concentrate quality, high metal loss, and greater environmental pressure.

[0005] Therefore, it is an urgent problem to be solved at this stage to develop and design a physical beneficiation method that can effectively separate pyrite and chalcopyrite from copper-molybdenum concentrate, improve the beneficiation index and recovery rate of valuable minerals, do not require the use of reagents, have a small pollution source and is green and environmentally friendly. The method of gravity separation and classification optimization magnetic separation of copper-molybdenum concentrate is a problem that needs to be solved urgently. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention provides a method for separating copper-molybdenum concentrate by gravity separation and classification optimization and magnetic separation. The method adopts the physical beneficiation method and selects reasonable slurry gravity separation, screening and classification, coarse particle strong magnetic roughing, coarse particle strong magnetic scavenging, fine particle strong magnetic roughing, fine particle strong magnetic concentration, fine particle strong magnetic scavenging, solid-liquid separation and other combined beneficiation process flows. The method effectively solves the technical problems existing in the conventional copper-molybdenum concentrate sorting process, such as poor sorting effect, high metal loss, low concentrate quality, large amount of reagents, long process flow, high production cost, multiple pollution sources and great environmental pressure. The method improves the beneficiation index and recovery rate of valuable minerals. Moreover, each operation section is green and environmentally friendly and suitable for large-scale production and application.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] The present invention provides a method for gravity separation classification optimization magnetic separation separation of copper-molybdenum concentrate, comprising the following steps:

[0009] S1: Slurry preparation and gravity separation: The copper-molybdenum concentrate, water and dispersant are mixed into slurry and then subjected to gravity separation to obtain heavy minerals and light minerals, and the heavy minerals are discharged into the first tailings sedimentation tank;

[0010] S2: Screening and grading: Screening the light minerals to obtain coarse particles on the sieve and fine particles under the sieve;

[0011] S3: strong magnetic roughing of coarse particles: the coarse particles on the screen are subjected to magnetic separation under a first magnetic field strength to obtain a first magnetic substance and a first non-magnetic substance, and the first non-magnetic substance is discharged into a first concentrate sedimentation tank;

[0012] S4: Coarse-grained strong magnetic sweeping: The first magnetic material is subjected to magnetic separation under a second magnetic field strength to obtain a second magnetic material and a second non-magnetic material, the second magnetic material is discharged into a second tailings sedimentation tank, and the second non-magnetic material is discharged into a second concentrate sedimentation tank;

[0013] S5: fine particle strong magnetic roughing separation: the fine particles under the sieve are subjected to magnetic separation under a third magnetic field strength to obtain a third magnetic material and a third non-magnetic material;

[0014] S6: fine-grained strong magnetic separation: the third non-magnetic material is subjected to magnetic separation under a fourth magnetic field strength to obtain a fourth magnetic material and a fourth non-magnetic material, and the fourth non-magnetic material is discharged into the first concentrate sedimentation tank;

[0015] S7: fine-grained strong magnetic sweeping: the third magnetic material and the fourth magnetic material are mixed and then subjected to magnetic separation under a fifth magnetic field strength to obtain a fifth magnetic material and a fifth non-magnetic material, wherein the fifth magnetic material is discharged into the second tailings sedimentation tank, and the fifth non-magnetic material is discharged into the second concentrate sedimentation tank;

[0016] S8: Solid-liquid separation: The products in the first tailings sedimentation pond, the second tailings sedimentation pond, the first concentrate sedimentation pond and the second concentrate sedimentation pond are subjected to solid-liquid separation operations respectively, and the separated solids are sulfur concentrate, copper rough concentrate, special grade molybdenum concentrate and high-quality molybdenum concentrate respectively, and the separated filtrate is recycled.

[0017] As a preferred technical solution, in step S1, the dispersant is set to sodium hexametaphosphate; the concentration of the slurry is set to 20%; and the slurry is re-selected using a spiral chute.

[0018] As a preferred technical solution, in step S2, the light mineral is screened using a high-frequency vibrating screen, and the mesh size of the high-frequency vibrating screen is set to 300 meshes.

[0019] As a preferred technical solution, in step S3, the first magnetic field strength is set to 5.0-5.5 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to 10×20 mm diamond-shaped high-magnetic permeability stainless steel plate mesh.

[0020] As a preferred technical solution, in step S4, the second magnetic field strength is set to 4.5-5.0 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to a combined diamond high magnetic permeability stainless steel plate mesh with specifications of 10×20mm and 15×30mm and a ratio of 2:1.

[0021] As a preferred technical solution, in step S5, the third magnetic field strength is set to 5.0-5.5 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to 5×10 mm diamond-shaped high-magnetic permeability stainless steel plate mesh.

[0022] As a preferred technical solution, in step S6, the fourth magnetic field strength is set to 5.5-6.0 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to a combined diamond high magnetic permeability stainless steel plate mesh with specifications of 3×6mm and 5×10mm and a ratio of 2:1.

[0023] As a preferred technical solution, in step S7, the fifth magnetic field strength is set to 5.0-5.5 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to a combined diamond high magnetic permeability stainless steel plate mesh with specifications of 3×6mm and 5×10mm and a ratio of 1:1.

[0024] As a preferred technical solution, in step S8, the product in the first tailings sedimentation tank is subjected to solid-liquid separation using a disc filter, and the separated solid is the sulfur concentrate; the product in the second tailings sedimentation tank is subjected to solid-liquid separation using a disc filter, and the separated solid is the copper rough concentrate; the product in the first concentrate sedimentation tank is subjected to solid-liquid separation using a plate and frame filter press, and the separated solid is the special grade molybdenum concentrate; the product in the second concentrate sedimentation tank is subjected to solid-liquid separation using a plate and frame filter press, and the separated solid is the high-quality molybdenum concentrate; the separated filtrate contains flotation agent, which can be returned to the flotation separation operation for recycling.

[0025] As a preferred technical solution, in step S8, the sulfur grade in the sulfur concentrate is 43.86%; the copper grade in the copper rough concentrate is 9.13%; the molybdenum grade in the special grade molybdenum concentrate is 53.18%; and the molybdenum grade in the high-quality molybdenum concentrate is 46.64%.

[0026] The beneficial effects of the present invention are as follows:

[0027] 1. The present invention adopts a physical beneficiation method based on the differences in physical properties such as the flaky structure of molybdenite, the particle size distribution of chalcopyrite, and the large density of pyrite, and selects reasonable slurry preparation re-selection, screening and grading, coarse-grained strong magnetic roughing selection, coarse-grained strong magnetic scavenging selection, fine-grained strong magnetic roughing selection, fine-grained strong magnetic concentration, fine-grained strong magnetic scavenging selection, solid-liquid separation and other combined beneficiation process flows, and can separate four industrial products, namely, sulfide concentrate, special-grade molybdenum concentrate, high-quality molybdenum concentrate and copper rough concentrate, from copper-molybdenum concentrate, thereby greatly improving the industrial added value of each product, effectively solving the technical problems existing in the conventional copper-molybdenum concentrate separation process, such as poor separation effect, high metal loss, low concentrate quality, large reagent dosage, long process flow, high production cost, multiple pollution sources, and high environmental pressure, thereby improving the beneficiation index and recovery rate of valuable minerals, and each operation section is green and environmentally friendly, and is suitable for large-scale production and application.

[0028] 2. The present invention selects a spiral chute, a high-frequency vibrating screen, a low-temperature superconducting magnetic separator, a filter press and other equipment for organic combination according to the physical and chemical properties of different minerals contained in the copper-molybdenum concentrate, such as the content, particle size, density, floatability, specific magnetic susceptibility, etc., and selects appropriate mesh number, screening particle size, medium matching, magnetic field strength, roughing selection, scavenging selection, and concentrating selection conditions. The process is scientific, the configuration is reasonable, the process is optimized, and the sorting is obvious.

[0029] 3. The present invention adds a dispersant to the copper-molybdenum concentrate and prepares it into a suitable slurry concentration, and selects a spiral chute as a gravity separation device, so that heavy minerals such as pyrite and magnetic iron with high density can be pre-selected. Due to the characteristics of flaky structure and hydrophobicity, molybdenite is discharged with tailings under the action of water flow and centrifugal force, thereby improving the quality of molybdenum concentrate in subsequent operations; a 300-mesh high-frequency vibrating screen is selected for classification, which can separate coarse flaky molybdenite from fine flaky or powdery molybdenite, and produce two products: coarse particles on the screen (high molybdenum and low copper) and fine particles under the screen (medium molybdenum and high copper); a low-temperature superconducting magnetic separator is selected in a high field strength and wide medium strip. By roughing the coarse particles on the +300 mesh sieve under the condition of high field strength and narrow medium, a special-grade coarse flaky molybdenum concentrate product can be obtained; by selecting a low-temperature superconducting magnetic separator to rough and finely select the fine particles under the -300 mesh sieve under the condition of high field strength and narrow medium, a first-grade fine flaky molybdenum concentrate product can be obtained, which can be combined with the +300 mesh molybdenum concentrate to form a special-grade molybdenum concentrate product; the magnetic materials obtained by superconducting sweeping of the coarse particles on the sieve and the fine particles under the sieve both carry or adhere to part of the molybdenite, and the superconducting magnetic separator is used to sweep and select them under the conditions of reducing the magnetic field strength and widening the medium network, respectively, to produce two products: high-quality molybdenum concentrate and rough copper concentrate.

[0030] 4. The filtrate produced by the solid-liquid separation operation of the present invention contains a certain amount of flotation reagent, which can be returned to the flotation separation operation for repeated use, thereby reducing the cost of reagent use. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 The present invention is a process flow chart of an embodiment of a method for separating copper-molybdenum concentrate by gravity separation and classification optimization and magnetic separation. DETAILED DESCRIPTION

[0032] In order to facilitate understanding by those skilled in the art, the present invention is further described below with reference to the accompanying drawings.

[0033] A copper-molybdenum production enterprise in Henan Province adopts the conventional beneficiation process of "crushing, grinding, mixed flotation, copper suppression and molybdenum flotation" to produce molybdenum sulphate concentrate, in which the molybdenum content is 44-49% and the copper content is 0.7-6.0%. The specific production indicators will fluctuate with the change of the grade of the original ore. The average molybdenum content of this type of molybdenum sulphate concentrate (i.e. copper-molybdenum concentrate) is 46.52% and the average copper content is 2.63%. The molybdenum content has reached the requirement of 45% for secondary products, but the copper content is far higher than the quality standard of 0.3-1.0%. The beneficiation plant produces tens of thousands of tons of copper-molybdenum concentrate with excessive copper content every year, which seriously affects the production efficiency of the enterprise. In recent years, it has commissioned various well-known universities to do a lot of research on flotation, magnetic separation and even chemical beneficiation, but none of them has achieved good separation effects or is not suitable for industrial production.

[0034] Through analysis and research, it was found that the molybdenum in the copper-molybdenum concentrate is mainly molybdenite, and the copper is mainly chalcopyrite, with a small amount of pyrite, magnetic iron, etc.; the mineral composition is relatively simple, molybdenite has a flaky structure and good natural hydrophobicity, chalcopyrite has a relatively fine particle size and good floatability, pyrite is medium-fine particles, and there is a small amount of magnetic iron; in addition, the copper-molybdenum concentrate contains a large amount of flotation agents such as diesel, kerosene, xanthate, and frothers. The flaky molybdenite with good floatability is easy to float on the surface of the slurry, there are fewer gangue minerals, the monomer dissociation degree between the minerals is better, there are fewer intergrowths, and a small amount of flocculence is produced due to excessive agents.

[0035] Suspension sedimentation test on copper-molybdenum concentrate found that the copper-molybdenum content in overflow and sediment was similar; shaking table gravity separation test found that heavy minerals were mainly pyrite with high density and a small amount of magnetic iron, and the copper-molybdenum content in the middlings and tailings obtained by the shaking table was similar, indicating that the copper-molybdenum concentrate cannot be effectively separated by gravity method using hydrocyclones or gravity separation equipment; when the mixed concentrate was screened for particle size, it was found that the molybdenum content in the +300 mesh size increased to more than 52%, while the copper content decreased significantly, the molybdenum content in the -300 mesh and especially -600 mesh size was significantly reduced, while the copper content was significantly increased. This occurrence state shows that the flaky structure of molybdenite and the fine-grained structure of chalcopyrite are conducive to the smooth progress of the separation process; at the same time, molybdenite is non-magnetic, while chalcopyrite and pyrite are weakly magnetic, and can be separated by a strong magnetic separation process.

[0036] Please refer to Figure 1 Table 1 is a specific implementation case of the copper-molybdenum concentrator using a method for gravity separation, classification and optimization of magnetic separation of copper-molybdenum concentrate provided by the present invention, including the following steps.

[0037] S1: Slurry preparation for gravity separation: 3‰ sodium hexametaphosphate dispersant is added to the copper-molybdenum concentrate and water is added to make a slurry concentration of 20% and stirred for 5 minutes. A spiral chute is used for gravity separation to obtain heavy minerals and light minerals. Among them, the main component of heavy minerals is pyrite with a relatively high density. The heavy minerals contain 43.86% sulfur and are discharged into the first tailings sedimentation pond as sulfur concentrate.

[0038] S2: Screening and grading: The light minerals with lower density are graded using a high-frequency vibrating screen with a mesh size of 300 mesh, and the coarse particles on the +300 mesh screen and the fine particles under the -300 mesh screen are sorted out; among them, the coarse particles on the +300 mesh screen contain 53.17% molybdenum and 0.76% copper, with a higher molybdenum content and a lower copper content; the fine particles under the -300 mesh screen contain 43.56% molybdenum and 3.85% copper, with a medium molybdenum content and a higher copper content.

[0039] S3: Strong magnetic roughing of coarse particles: The coarse particles on the +300 mesh sieve are configured into a slurry concentration of 16%, and enter the superconducting magnetic separator for strong magnetic roughing operation under the first magnetic field strength. The first magnetic field strength is 5.0-5.5 Tesla, and the magnetic separation medium is 10×20mm diamond-shaped high-magnetic permeability stainless steel plate mesh, to obtain the first magnetic material and the first non-magnetic material; wherein, the main component of the first magnetic material is coarse-grained, weakly magnetic chalcopyrite, and the first magnetic material contains 1.96% copper; the first non-magnetic material is molybdenum concentrate with a molybdenum grade of 54.78%, which is discharged into the first concentrate sedimentation tank as a special grade molybdenum concentrate.

[0040] S4: Coarse-grained strong magnetic sweeping: The first magnetic material enters the superconducting magnetic separator for strong magnetic sweeping under the second magnetic field strength. The second magnetic field strength is 4.5-5.0 Tesla, and the magnetic separation medium is a 2:1 ratio of 10×20mm and 15×30mm combined diamond-shaped high-magnetic permeability stainless steel plate mesh to obtain the second magnetic material and the second non-magnetic material; wherein, the main component of the second magnetic material is coarse-grained chalcopyrite, and the second magnetic material contains 6.25% copper, which is discharged into the second tailings sedimentation tank as a copper coarse concentrate; the second non-magnetic material is a molybdenum concentrate with a molybdenum grade of 48.16%, which is discharged into the second concentrate sedimentation tank as a high-quality molybdenum concentrate.

[0041] S5: Strong magnetic roughing of fine particles: The fine particles under the -300 mesh sieve are configured into a slurry concentration of 13%, and enter the superconducting magnetic separator for strong magnetic roughing operation under the third magnetic field strength. The third magnetic field strength is 5.0-5.5 Tesla, and the magnetic separation medium is 5×10mm diamond-shaped high-magnetic permeability stainless steel plate mesh to obtain the third magnetic material and the third non-magnetic material; among which, the main component of the third magnetic material is fine-grained, weakly magnetic chalcopyrite, the third magnetic material contains 7.06% copper and 34.48% molybdenum; the third non-magnetic material contains 44.82% molybdenum.

[0042] S6: Fine-grained strong magnetic concentration: The third non-magnetic material is configured to a 10% slurry concentration, and enters the superconducting magnetic separator for strong magnetic concentration under the fourth magnetic field strength, which can further remove the fine-grained chalcopyrite in the third non-magnetic material. The fourth magnetic field strength is 5.5-6.0 Tesla, and the magnetic separation medium is a 2:1 ratio of 3×6mm and 5×10mm combined diamond high-magnetic permeability stainless steel plate mesh to obtain the fourth magnetic material and the fourth non-magnetic material; wherein, the fourth magnetic material contains 8.51% copper and 30.15% molybdenum; the fourth non-magnetic material is a molybdenum concentrate with a molybdenum grade of 50.46%, which is discharged into the first concentrate sedimentation tank as a special grade molybdenum concentrate.

[0043] S7: Fine-grained strong magnetic sweeping: The third magnetic material and the fourth magnetic material are configured to a 10% slurry concentration, and enter the superconducting magnetic separator to perform strong magnetic sweeping under the fifth magnetic field strength, which can enhance the separation of molybdenite and fine-grained chalcopyrite with weak magnetism carried by the third magnetic material and the fourth magnetic material. The fifth magnetic field strength is 5.0-5.5 Tesla, and the magnetic separation medium is a 1:1 ratio of 3×6mm and 5×10mm combined diamond high-magnetic permeability stainless steel plate mesh to obtain the fifth magnetic material and the fifth non-magnetic material; among them, the fifth magnetic material contains 9.65% copper and is discharged into the second tailings sedimentation tank as a copper rough concentrate; the fifth non-magnetic material is a molybdenum concentrate with a molybdenum grade of 44.16%, which is discharged into the second concentrate sedimentation tank as a high-quality molybdenum concentrate.

[0044] S8: Solid-liquid separation: The heavy minerals in the first tailings sedimentation tank are subjected to solid-liquid separation by a disc filter to obtain a sulfur concentrate product with an effective sulfur grade of 43.86%; the first non-magnetic material and the fourth non-magnetic material in the first concentrate sedimentation tank are subjected to solid-liquid separation by a plate and frame filter press to obtain a special-grade molybdenum concentrate product with a molybdenum grade of 53.18% and a copper content of 0.28%; the second non-magnetic material and the fifth non-magnetic material in the second concentrate sedimentation tank are subjected to solid-liquid separation by a plate and frame filter press to obtain a high-quality molybdenum concentrate product with a molybdenum grade of 46.64% and a copper content of 0.68%; the second magnetic material and the fifth magnetic material in the second tailings sedimentation tank are subjected to solid-liquid separation by a disc filter to obtain a copper rough concentrate product with a copper grade of 9.13% and a molybdenum content of 24.45%. The copper rough concentrate product can be further returned to the flotation separation operation for copper and molybdenum separation to produce copper concentrate and molybdenum concentrate respectively.

[0045] Table 1 Ore dressing indexes of copper-molybdenum concentrate separated by gravity separation and optimization of magnetic separation %

[0046]

[0047] It should be noted that in the mineral processing of this embodiment, each operation section adopts a green and environmentally friendly physical mineral processing process. The tail water produced after the solid-liquid separation operation of each product contains a certain amount of flotation reagent, which can be returned to the flotation separation operation for repeated use.

[0048] According to the differences in the physical and chemical properties of pyrite, molybdenite, chalcopyrite and the like contained in the copper-molybdenum concentrate, the present invention first adopts a gravity separation process to select the pyrite with a larger density in advance, and then adopts a high-frequency vibrating screen for classification to produce coarse particles on a +300 mesh sieve and fine particles under a -300 mesh sieve; wherein the coarse particles on the +300 mesh sieve have a higher molybdenum content and a lower copper content, and a superconducting magnetic separator with high field strength and wide medium conditions is used for one rough separation to obtain a special-grade molybdenum concentrate; the fine particles under the -300 mesh sieve have a lower molybdenum content and a higher copper content, and a superconducting magnetic separator with high field strength and narrow medium conditions is used for one rough separation. Superconducting magnetic separator under medium conditions can obtain special-grade molybdenum concentrate by one roughing and one fine separation; the magnetic material separated by magnetic separation will carry or adhere to some molybdenite with more oil on the surface, and then it will be swept and separated by superconducting magnetic separator to obtain high-quality molybdenum concentrate and rough copper concentrate with high copper content respectively; the method provided by the present invention can produce four industrial products, namely sulfur concentrate, special-grade molybdenum concentrate, high-quality molybdenum concentrate and rough copper concentrate, effectively improving the separation index and recovery rate of each product and greatly increasing the production efficiency of the enterprise.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation, characterized in that: The following steps are involved: S1: Slurry preparation and gravity separation: The copper-molybdenum concentrate, water and dispersant are mixed into slurry and then subjected to gravity separation to obtain heavy minerals and light minerals, and the heavy minerals are discharged into the first tailings sedimentation tank; S2: Screening and grading: Screening the light minerals to obtain coarse particles on the +300 mesh sieve and fine particles under the -300 mesh sieve; S3: strong magnetic roughing of coarse particles: the coarse particles on the screen are subjected to magnetic separation under a first magnetic field strength to obtain a first magnetic substance and a first non-magnetic substance, and the first non-magnetic substance is discharged into a first concentrate sedimentation tank; S4: Coarse-grained strong magnetic sweeping: The first magnetic material is subjected to magnetic separation under a second magnetic field strength to obtain a second magnetic material and a second non-magnetic material, the second magnetic material is discharged into a second tailings sedimentation tank, and the second non-magnetic material is discharged into a second concentrate sedimentation tank; S5: fine particle strong magnetic roughing separation: the fine particles under the sieve are subjected to magnetic separation under a third magnetic field strength to obtain a third magnetic material and a third non-magnetic material; S6: fine-grained strong magnetic separation: the third non-magnetic material is subjected to magnetic separation under a fourth magnetic field strength to obtain a fourth magnetic material and a fourth non-magnetic material, and the fourth non-magnetic material is discharged into the first concentrate sedimentation tank; S7: fine-grained strong magnetic sweeping: the third magnetic material and the fourth magnetic material are mixed and then subjected to magnetic separation under a fifth magnetic field strength to obtain a fifth magnetic material and a fifth non-magnetic material, wherein the fifth magnetic material is discharged into the second tailings sedimentation tank, and the fifth non-magnetic material is discharged into the second concentrate sedimentation tank; S8: Solid-liquid separation: The products in the first tailings sedimentation pond, the second tailings sedimentation pond, the first concentrate sedimentation pond and the second concentrate sedimentation pond are subjected to solid-liquid separation operations respectively, and the separated solids are sulfur concentrate, copper rough concentrate, special grade molybdenum concentrate and high-quality molybdenum concentrate respectively, and the separated filtrate is recycled.

2. The method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 1 is characterized in that: In step S1, the dispersant is sodium hexametaphosphate; the concentration of the slurry is set to 20%; and the slurry is re-selected using a spiral chute.

3. The method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 1, characterized in that: In step S2, the light minerals are screened using a high-frequency vibrating screen, and the mesh size of the high-frequency vibrating screen is set to 300 meshes.

4. The method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 1, characterized in that: In step S3, the first magnetic field strength is set to 5.0-5.5 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to 10×20 mm diamond-shaped high-magnetic permeability stainless steel plate mesh.

5. A method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 1 or 4, characterized in that: In step S4, the second magnetic field strength is set to 4.5-5.0 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to a combined diamond high magnetic permeability stainless steel plate mesh with specifications of 10×20mm and 15×30mm and a ratio of 2:

1.

6. The method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 1, characterized in that: In step S5, the third magnetic field strength is set to 5.0-5.5 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to 5×10 mm diamond-shaped high-magnetic permeability stainless steel plate mesh.

7. The method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 6 is characterized in that: In step S6, the fourth magnetic field strength is set to 5.5-6.0 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to a combined diamond high magnetic permeability stainless steel plate mesh with specifications of 3×6mm and 5×10mm and a ratio of 2:

1.

8. The method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 7 is characterized in that: In step S7, the fifth magnetic field strength is set to 5.0-5.5 Tesla, a superconducting magnetic separator is used for magnetic separation, and the magnetic separation medium used is set to a combined diamond high magnetic permeability stainless steel plate mesh with specifications of 3×6mm and 5×10mm and a ratio of 1:

1.

9. The method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 1, characterized in that: In step S8, the product in the first tailings sedimentation tank is subjected to solid-liquid separation using a disc filter, and the separated solid is the sulfur concentrate; the product in the second tailings sedimentation tank is subjected to solid-liquid separation using a disc filter, and the separated solid is the copper rough concentrate; the product in the first concentrate sedimentation tank is subjected to solid-liquid separation using a plate and frame filter press, and the separated solid is the special grade molybdenum concentrate; the product in the second concentrate sedimentation tank is subjected to solid-liquid separation using a plate and frame filter press, and the separated solid is the high-quality molybdenum concentrate; the separated filtrate contains flotation reagents, which can be returned to the flotation separation operation for recycling.

10. A method for separating copper-molybdenum concentrate by gravity classification optimization magnetic separation according to claim 1 or 9, characterized in that: In step S8, the sulfur grade in the sulfur concentrate is 43.86%; the copper grade in the copper rough concentrate is 9.13%; the molybdenum grade in the special grade molybdenum concentrate is 53.18%; and the molybdenum grade in the high-quality molybdenum concentrate is 46.64%.

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