Magnetic-gravity combined grading separation method for comprehensively recovering iron, uranium and boron in low-grade uranium-boron-containing magnesiferous iron ore

Abstract

The invention discloses a magnetic-gravity combined grading separation method for comprehensive recovery of iron, uranium and boron in low-grade uranium-boron-containing magnesiferous iron ore, which comprises the following steps: firstly, carrying out multi-section closed-circuit crushing and wet screening on raw ore to obtain ore pulp of-5mm, and then carrying out wet tailings-discarding magnetic separation and scavenging separation to obtain bulk concentrate; the concentrate is sequentially subjected to two-section closed circuit grinding classification, gradient magnetic field magnetic separation and high-frequency screening purification are matched, iron fine powder is obtained, and uranium-boron-containing tailings are separated out; then grading is conducted through a multi-specification hydrocyclone, a KGS concentrating machine, a suspended vibration conical surface concentrating machine and shaking table reselection are combined, uranium ore in tailings of different sources is recycled, and meanwhile boron concentrate is obtained through enrichment; the method has the advantages that the process is closed-loop and efficient, the problem that the low-grade fine-grained uranium ore is difficult to enrich is solved in a targeted manner, and the comprehensive utilization rate of resources is high; complex chemicals are not needed, the pollution problem of a traditional process is avoided, environmental protection is achieved, operation is stable, and three components can be synchronously recycled.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology and comprehensive utilization of mineral resources, and specifically relates to a magnetic gravity combined beneficiation method for comprehensively recovering three valuable components, iron, uranium and boron, from low-grade, complex uranium-boron-magnesium iron ore. Background Technology

[0002] Uranium resources are a dual strategic pillar of national energy and defense security, surpassing most minerals such as rare earth elements. They are a core "strategic hard currency" in great power competition. As the core fuel for nuclear energy, it provides stable baseload electricity with an energy density millions of times greater than fossil fuels, making it a key zero-carbon energy source for achieving the "dual-carbon" goal. Uranium-235 is also a core raw material for strategic equipment such as nuclear weapons and nuclear submarines, directly determining a nation's nuclear deterrent capability. For China, building a three-pronged uranium resource security system integrating resources, technology, and security is not only an inevitable choice to address global supply and demand imbalances and supply chain risks, but also a core strategic support for achieving energy independence, safeguarding national security, and promoting energy transformation.

[0003] The boron-iron ore from Wengquangou in Liaoning Province has a complex mineral composition. Iron minerals are mainly found in magnetite, boron is mainly found in boromagnesite with a small amount in boron-iron ore, uranium minerals are crystalline uranium ore, magnesium minerals are mainly serpentine with phlogopite as a secondary component, and the harmful element sulfur mainly exists in the form of pyrrhotite and pyrite. The magnetite in the ore has a fine particle size and complex interlocking relationships with other target minerals, making it difficult to completely separate into individual particles even through fine grinding. Therefore, a staged grinding-stage magnetic separation process is recommended for its separation.

[0004] The uranium minerals in the ore are mainly crystalline uranium minerals, occurring as irregular granules or microparticles. They mostly fill the edges, intergranular spaces, or fissures of magnetite, borosilicate, boraxite, and serpentine. In some coarse-grained fissures, magnetite can be seen filling the fissures as fine veins. In general, the crystalline uranium minerals in the ore are low in content, highly dispersed, and fine-grained, and are closely related to magnetite, borosilicate, boraxite, and serpentine.

[0005] The original uranium beneficiation process involves two stages of grinding and iron tailings classification followed by shaking table separation of the sediment. Because uranium beneficiation is at the end of the overall mineral processing, it suffers from significant losses at the front end, resulting in low yields and recovery rates, which restricts the output of subsequent hydrometallurgical products. Therefore, developing a novel mineral processing technology that can intervene early, precisely capture the fine-grained uranium ore lost in the early stages of the process, and achieve efficient and synergistic recovery of iron, uranium, and boron has become an urgent technological need to address the bottlenecks in the utilization of this strategic associated mineral resource. Summary of the Invention

[0006] To address the aforementioned problems, this invention discloses a magnetic-gravity combined classification and separation method for the comprehensive recovery of iron, uranium, and boron from low-grade uranium-boron-magnesium iron ore.

[0007] The specific technical solution is as follows:

[0008] A combined magnetic and gravity separation method for the comprehensive recovery of iron, uranium, and boron in low-grade uranium-boron-magnesium iron ore is disclosed. This method is used to process uranium-boron-magnesium iron ore with a TFe content of 22.5%–30%, a B2O3 grade of 4.2%–7.3%, and a U grade of 0.0004%–0.0005%. The method comprises the following steps:

[0009] S1 Crushing Process

[0010] The raw ore with a particle size of 300mm~1000mm is processed sequentially through coarse crushing, medium crushing, dry screening, fine crushing and high-pressure roller milling. The output of high-pressure roller milling is mixed with water to form a slurry and then wet screening is performed. The +5mm ore is returned to the medium crusher to form a closed circuit, and the -5mm ore enters the next process.

[0011] S2 Wet Tail Throwing Magnetic Separation Process

[0012] The -5mm ore obtained in step S1 is fed into a magnetic separator for wet tailings magnetic separation to separate concentrate A and tailings A; tailings A enters scavenging I and magnetic separation to obtain tailings I, while concentrate A enters the subsequent grinding process.

[0013] S3 single-stage grinding-classification-weak magnetic separation process

[0014] Concentrate A enters ball mill I for grinding. The grinding product is sent to hydraulic classification I for further classification. The underflow from hydraulic classification I is returned to ball mill I to form a closed-circuit grinding system. The overflow from hydraulic classification I is sent to magnetic separation I for weak magnetic separation to separate concentrate B and tailings B. Tailings B enters scavenging magnetic separation to obtain concentrate C. Concentrate B and concentrate C are sent together to high-frequency screening to separate oversize material D and undersize material E.

[0015] S4 Two-Stage Grinding-Classification-Weak Magnetic Separation Process

[0016] The material D oversizes is fed into a magnetic separator for magnetic separation. The concentrate from the magnetic separator enters ball mill II for grinding. The output of ball mill II and the tailings from the magnetic separator are returned to the high-frequency screening to form a closed-circuit grinding system. The material E undersizes is fed into magnetic separator II for magnetic separation to obtain concentrate F and tailings F. Concentrate F is fed into magnetic separator III for magnetic separation to obtain concentrate G and tailings G. Tailings F and tailings G are fed into scavenging separator III for magnetic separation to obtain concentrate H. Concentrate H is returned to the high-frequency screening. Concentrate G is vacuum filtered to obtain iron concentrate. The tailings from scavenging separator III are tailings H.

[0017] S5 uranium ore and boron concentrate recovery process

[0018] S5a tailings I is fed into hydraulic classification II for classification. The sediment from hydraulic classification II enters the integrated tailings. The overflow is treated by a slag screen, and the undersize material is sent to a KGS concentrator for gravity separation. The concentrate from the KGS concentrator is sent to a suspended cone concentrator for further cleaning to obtain uranium concentrate I.

[0019] The tailings J from the S5b scavenging II process are sent to the third hydraulic classification stage. The sediment from the third hydraulic classification stage is sent to a 90° shaking table for separation to obtain uranium concentrate II. The overflow is sent to the fifth hydraulic classification stage.

[0020] S5c tailings H are sent to hydraulic classification stage IV. The sediment from hydraulic classification stage IV is sent to a 120 shaking table for separation to obtain uranium concentrate III. The overflow is sent to hydraulic classification stage V. The overflow from hydraulic classification stage V is used to obtain boron concentrate. The tailings are then sent to the comprehensive tailings.

[0021] The discharged tailings are the final tailings, and uranium concentrate I, uranium concentrate II, and uranium concentrate III are combined into the final uranium concentrate.

[0022] In step S1, the coarse crushing uses a jaw crusher with a discharge opening of 170mm; the medium crushing uses a cone crusher with a discharge opening of 45mm; the dry screening uses a double-layer circular vibrating screen with a screen hole of 12mm~14mm; the fine crushing uses a cone crusher with a discharge opening of 20mm; the high-pressure roller mill pressure is set to 90bar; and the wet screening screen hole is 5mm.

[0023] In step S3, magnetic separation I is a drum magnetic separator with a magnetic field strength of 120KA / m~165KA / m; scavenging II is a drum magnetic separator with a magnetic field strength of 350KA / m~500KA / m; high-frequency screening uses a five-layer high-frequency screen with a screen aperture of 0.1mm.

[0024] In step S5b, the third hydraulic stage uses a hydrocyclone with a diameter of 500 mm and an operating pressure of 0.08 MPa to 0.11 MPa; in step S5c, the fourth hydraulic stage uses a hydrocyclone with a diameter of 100 mm and an operating pressure of 0.08 MPa to 0.11 MPa; and the fifth hydraulic stage uses a hydrocyclone with a diameter of 350 mm and an operating pressure of 0.18 MPa to 0.25 MPa.

[0025] The advantages of this invention are: For low-grade uranium-boron-magnesium iron ore with a TFe content of 22.5%~30%, a B2O3 grade of 4.2%~7.3%, and a U grade of 0.0004%~0.0005%, this invention employs a combined magnetic and gravity classification and separation process to achieve comprehensive and efficient recovery of iron, uranium, and boron, effectively solving the problems of large losses at the front end of the original process, difficulty in enriching low-grade fine-grained uranium ore, and low resource utilization. Through a closed-circuit crushing process combining coarse, medium, and fine crushing with high-pressure roller mills, and a two-stage closed-circuit grinding-classification-magnetic separation process, the efficiency is significantly improved. The system improves the efficiency of iron concentrate production and the accuracy of uranium and boron separation. It employs a combination of KGS concentrators and vibrating cone concentrators, along with 90° and 120° shaking tables for grading and separation. This design not only meets the separation requirements of fine-grained uranium ore but also significantly improves the uranium concentrate recovery rate to meet the requirements of hydrometallurgical production. The entire process requires no complex chemical reagents, making it highly environmentally friendly. Furthermore, the equipment is compact, easy to operate and maintain, and operates stably. While achieving efficient utilization of waste resources and improving economic benefits, it provides a highly adaptable and reliable technical solution for the comprehensive recovery of low-grade associated crystalline uranium ore. Attached Figure Description

[0026] Figure 1 This is a flowchart illustrating the working process of the present invention. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Implementation Plan Overview

[0029] This implementation plan targets low-grade uranium-boron-magnesium iron ore with a TFe content of 22.5%~30%, a B2O3 grade of 4.2%~7.3%, and a U grade of 0.0004%~0.0005%. It adopts a magnetic-gravity combined classification and separation process of "crushing-wet tailings throwing magnetic separation-two-stage grinding and classification magnetic separation-uranium-boron combined recovery" to solve the technical problems of large uranium ore loss at the front end of the original process, difficulty in enriching fine-grained uranium ore, and low comprehensive utilization rate of resources, and achieves efficient separation and recovery of the three valuable components of iron, uranium, and boron.

[0030] Raw material preparation

[0031] (a) Properties of the raw ore

[0032] Mineral composition: Iron minerals are mainly found in magnetite, boron is mainly found in boromagnesite, uranium minerals are crystalline uranium minerals, magnesium minerals are mainly serpentine, and the harmful element sulfur exists in the form of pyrrhotite and pyrite.

[0033] Raw material specifications: The raw ore has a particle size of 300mm~1000mm, of which the -0.074mm particle size accounts for more than 80% in the subsequent fine-grained uranium ore samples, and the relationship between magnetite and other minerals is complex.

[0034] (II) Requirements for raw material pretreatment

[0035] The raw ore must be free of large impurities and be evenly piled up after entering the site to avoid rain and clumping, ensuring continuous and stable feeding in the crushing process.

[0036] III. List of Core Equipment and Technical Specifications

[0037] Process Stage Equipment Name Model / Specification Key technical parameters Crushing system Jaw crusher Adapt to coarse crushing requirements 170mm discharge port Cone crusher (medium crusher) PYB2200 45mm discharge port Double-layer circular vibrating screen (dry screening) 2YA2460 12mm~14mm sieve aperture Cone crusher (fine crushing) HP500 20mm discharge opening High-pressure roller mill GM160-140 Work pressure 90 bar Linear screen (wet screening) zkk3061 5mm sieve aperture Magnetic separation system Drum magnetic separator (wet tailings) 1230 Magnetic Separator Suitable for -5mm slurry tailings disposal requirements Drum magnetic separator (Magnetic Separator I) 1230 Magnetic Separator Magnetic field strength 120KA / m~165KA / m Drum magnetic separator (Magnetic Separation II / III) 1230 Magnetic Separator Magnetic field strength 120KA / m~165KA / m Drum magnetic separator (scavenging I / II / III) 1230 Magnetic Separator Magnetic field strength 350 kA / m ~ 500 kA / m Concentrated magnetic separator 1230 Magnetic Separator Adapted for high-frequency screen material sorting Grinding and Classification System Overflow ball mill (Ball Mill I) 3660 Grinding particle size: -74μm accounts for 45%~55% Overflow ball mill (Ball Mill II) 3264 Grinding particle size: 80%~85% - 74μm Hydrocyclone (Hydraulic Classification I) 500mm in diameter 95mm undercut nozzle Hydrocyclone (Hydraulic Classification II) 610mm in diameter The undersand nozzle is 120mm, and the working pressure is adapted to the grading requirements. The overflow thickness of -0.074mm is ≥80%. Hydrocyclone (Hydraulic Classification III) 500mm in diameter The undersink nozzle is 80mm, and the working pressure is 0.08MPa~0.11MPa. Hydrocyclone (Hydraulic Classification IV) 100mm in diameter The undersink nozzle is 20mm, and the working pressure is 0.08MPa~0.11MPa. Hydrocyclone (Hydraulic Classifier V) 350mm in diameter The undersink nozzle is 70mm, and the working pressure is 0.18MPa~0.25MPa. Five-layer high frequency screen D4MVSK2418 0.1mm sieve aperture Re-selection and recycling system KGS mineral processing machine Gravity sorting type Feed concentration 12%~22%, rotation frequency 20Hz, feed rate 120kg / h~330kg / h Vibrating cone surface mineral concentrator Selected Rotation frequency 7.5Hz, vibration frequency 20Hz 90-degree shaking bed 6S Shaker Suitable for hydraulic classification and three-stage sand separation 120 shaking bed 6S Shaker Suitable for hydraulic classification and four-stage sedimentation. Slag screen Industrial-grade screening equipment Used for filtering impurities from hydraulic classification overflow. Vacuum Filter Disc vacuum filter Used for iron concentrate dehydration products Auxiliary equipment Pump pool, slurry pump Adapted for slurry conveying Ensure stable slurry flow in each process belt conveyor Adaptable to material transfer Used for closed-loop circulation and material conveying in ore crushing processes.

[0038] Detailed implementation steps

[0039] S1 Crushing Process (Constructing a Closed-Circuit Crushing System)

[0040] Primary crushing: Raw ore with a particle size of 300mm~1000mm is fed into a jaw crusher, with a discharge opening of 170mm. The crushed material is then conveyed to the intermediate crushing stage via a belt conveyor.

[0041] Medium crushing operation: The material enters the cone crusher, the discharge opening is set to 45mm, and after crushing, it is conveyed to a double-layer circular vibrating screen for dry screening.

[0042] Dry grading: The double-layer circular vibrating screen has a screen aperture of 12mm~14mm. The ore with a thickness of +12mm on the screen is returned to the fine crushing process via a belt conveyor, while the ore with a thickness of -12mm on the screen is conveyed to the high-pressure roller mill.

[0043] Fine crushing operation: +12mm ore enters the cone crusher, the discharge opening is set to 20mm, and the crushed product is combined with -12mm ore and enters the high-pressure roller mill.

[0044] High-pressure roller mill and wet screening: The high-pressure roller mill is set to a working pressure of 90 bar to roll the ore. After discharge, it is mixed with water to form a slurry, which is then fed into a linear screen with a screen size of 5 mm for wet screening. The ore with a thickness of +5 mm on the screen is returned to the intermediate crushing process via a belt to form a closed circuit, while the slurry with a thickness of -5 mm on the screen enters the next process.

[0045] S2 Wet Tail-Throwing Magnetic Separation Process

[0046] The -5mm slurry obtained from S1 is fed into a drum magnetic separator for wet tailings separation. The gangue minerals containing the surrounding rock are separated by magnetic separation to obtain concentrate A (a mixed mineral rich in iron, boron, and uranium) and tailings A. Tailings A is sent to scavenging separator I for secondary magnetic separation to recover a small amount of valuable minerals entrained in tailings A, and finally tailings I is obtained. The concentrate from scavenging separator I is combined with concentrate A and enters the grinding process together.

[0047] S3 One-stage grinding-classification-weak magnetic separation process

[0048] First stage of grinding: Concentrate A is fed into an overflow ball mill (ball mill I) for grinding, and the grinding concentration is controlled at 80% to ensure the initial liberation of minerals.

[0049] Hydraulic classification: The discharge from ball mill I is fed into a 500mm diameter hydrocyclone (hydraulic classification one) for classification. The underflow sand is returned to ball mill I via a slurry pump to form a closed-circuit grinding system, ensuring that the grinding particle size is -74μm and accounts for 45%~55% of the total. The overflow enters magnetic separator I.

[0050] Weak magnetic separation: The overflow is fed into a drum magnetic separator (magnetic separation I) for weak magnetic separation to separate concentrate B (rich in magnetite) and tailings B (rich in boron and uranium minerals).

[0051] Scavenging and screening: Tailings B is fed into scavenging II (high-intensity magnetic drum separator) to recover the magnetite entrained therein, and obtain concentrate C; concentrate B and concentrate C are fed together into a five-layer high-frequency screen to separate the oversize material D and the undersize material E.

[0052] S4 Two-stage grinding-classification-weak magnetic separation process

[0053] Two-stage closed-circuit grinding: The material D oversize from the high-frequency screen is fed into a thickening magnetic separator for magnetic enrichment. The concentrate from the thickening magnetic separator is fed into an overflow ball mill (ball mill II) for deep grinding, controlling the grinding particle size -74μm to account for 80%~85%, ensuring complete liberation of magnetite. The output of ball mill II and the tailings from the thickening magnetic separator are returned to the high-frequency screen to form a closed-circuit grinding system.

[0054] Multi-stage magnetic separation purification: The undersize material E from the high-frequency screen is fed into a drum magnetic separator (magnetic separation II) to separate concentrate F (magnetite) and tailings F (boron and uranium minerals); concentrate F is fed into a drum magnetic separator (magnetic separation III) for fine selection to obtain concentrate G (high-purity magnetite) and tailings G; tailings F and tailings G are fed into scavenging separator III (high-intensity magnetic drum separator) to recover a small amount of magnetite to obtain concentrate H, which is returned to the high-frequency screen for recycling; the tailings H from scavenging separator III are sent to the boron and uranium recovery process.

[0055] Iron concentrate production: Concentrate G is sent to a vacuum filter for dehydration to produce boron-containing iron concentrate, which is the final iron product.

[0056] S5 uranium ore and boron concentrate recovery process

[0057] S5a fine-grained uranium ore recovery (from tailings I)

[0058] Desliming and grading: Tailings I is fed into a 610mm diameter hydrocyclone (hydraulic classification II) for desliming and grading. The sediment (coarse gangue) enters the integrated tailings, and the overflow enters the slag screen.

[0059] Impurity filtration and gravity separation: The overflow is filtered through a slag screen to remove large impurities. The undersize material is fed into a KGS concentrator for gravity separation. The feed concentration is set to 12%~22%, the rotation frequency to 20Hz, and the feed rate to 120kg / h~330kg / h. Fine-grained crude uranium ore is recovered. The tailings from the KGS concentrator are sent to the comprehensive tailings.

[0060] Uranium ore beneficiation: Crude uranium ore is fed into a suspended conical concentrator, with a rotation frequency of 7.5Hz and a vibration frequency of 20Hz, for beneficiation and purification to obtain uranium concentrate I; the tailings from the suspended conical concentrator are sent to the comprehensive tailings.

[0061] S5b uranium ore recovery (from tailings J of scavenging II)

[0062] The tailings J (rich in uranium minerals) from scavenging II are fed into a 500mm diameter hydrocyclone (hydraulic classifier IIII) for classification. The sediment is fed into a 90° shaking table for gravity separation to recover uranium concentrate II. The tailings from the shaking table enter the integrated tailings, and the overflow from hydraulic classifier III is sent to hydraulic classifier V.

[0063] S5c uranium ore and boron concentrate combined recovery (from tailings H)

[0064] Classification and separation: Tailings H is fed into a 100mm diameter hydrocyclone (hydraulic classification IV) for classification, and the sediment is fed into a 120 shaking table for gravity separation to recover uranium concentrate III; the tailings from the shaking table enter the comprehensive tailings, and the overflow from hydraulic classification IV is sent to hydraulic classification V.

[0065] Boron concentrate purification: The overflows from hydraulic classification III and hydraulic classification IV enter a 350mm diameter hydrocyclone (hydraulic classification V) together, and the overflow (boron concentrate) is obtained through classification and enrichment. The tailings enter the comprehensive tailings.

Claims

1. A magnetic-gravity combined classification and separation method for the comprehensive recovery of iron, uranium, and boron in low-grade uranium-boron-magnesium iron ore, used to process uranium-boron-magnesium iron ore with a TFe content of 22.5%~30%, a B2O3 grade of 4.2%~7.3%, and a U grade of 0.0004%~0.0005%, characterized in that... The following steps are used to achieve this: S1 Crushing Process The raw ore with a particle size of 300mm~1000mm is processed sequentially through coarse crushing, medium crushing, dry screening, fine crushing and high-pressure roller milling. The output of high-pressure roller milling is mixed with water to form a slurry and then wet screening is performed. The +5mm ore is returned to the medium crusher to form a closed circuit, and the -5mm ore enters the next process. S2 wet tail throwing magnetic separation process The -5mm ore obtained in step S1 is fed into a magnetic separator for wet tailings magnetic separation to separate concentrate A and tailings A; tailings A enters scavenging I and magnetic separation to obtain tailings I, while concentrate A enters the subsequent grinding process. S3 single-stage grinding-classification-weak magnetic separation process Concentrate A enters ball mill I for grinding. The grinding product is sent to hydraulic classification I for further classification. The underflow from hydraulic classification I is returned to ball mill I to form a closed-circuit grinding system. The overflow from hydraulic classification I is sent to magnetic separation I for weak magnetic separation to separate concentrate B and tailings B. Tailings B enters scavenging magnetic separation to obtain concentrate C. Concentrate B and concentrate C are sent together to high-frequency screening to separate oversize material D and undersize material E. S4 Two-Stage Grinding-Classification-Weak Magnetic Separation Process The material D oversizes is fed into a magnetic separator for magnetic separation. The concentrate from the magnetic separator enters ball mill II for grinding. The output of ball mill II and the tailings from the magnetic separator are returned to the high-frequency screening to form a closed-circuit grinding system. The material E undersizes is fed into magnetic separator II for magnetic separation to obtain concentrate F and tailings F. Concentrate F is fed into magnetic separator III for magnetic separation to obtain concentrate G and tailings G. Tailings F and tailings G are fed into scavenging separator III for magnetic separation to obtain concentrate H. Concentrate H is returned to the high-frequency screening. Concentrate G is vacuum filtered to obtain iron concentrate. The tailings from scavenging separator III are tailings H. S5 uranium ore and boron concentrate recovery process S5a tailings I is fed into hydraulic classification II for classification. The sediment from hydraulic classification II enters the integrated tailings. The overflow is treated by a slag screen, and the undersize material is sent to a KGS concentrator for gravity separation. The concentrate from the KGS concentrator is sent to a suspended cone concentrator for further cleaning to obtain uranium concentrate I. The tailings J from the S5b scavenging II process are sent to the third hydraulic classification stage. The sediment from the third hydraulic classification stage is sent to a 90° shaking table for separation to obtain uranium concentrate II. The overflow is sent to the fifth hydraulic classification stage. S5c tailings H are sent to hydraulic classification stage IV. The sediment from hydraulic classification stage IV is sent to a 120 shaking table for separation to obtain uranium concentrate III. The overflow is sent to hydraulic classification stage V. The overflow from hydraulic classification stage V is used to obtain boron concentrate. The tailings are then sent to the comprehensive tailings. The discharged tailings are the final tailings, and uranium concentrate I, uranium concentrate II, and uranium concentrate III are combined into the final uranium concentrate.

2. The method as described in claim 1, characterized in that: In step S1, the coarse crushing uses a jaw crusher with a discharge opening of 170mm; the medium crushing uses a cone crusher with a discharge opening of 45mm; the dry screening uses a double-layer circular vibrating screen with a screen hole of 12mm~14mm; the fine crushing uses a cone crusher with a discharge opening of 20mm; the high-pressure roller mill pressure is set to 90bar; and the wet screening screen hole is 5mm.

3. The method as described in claim 1, characterized in that: In step S3, magnetic separation I is a drum magnetic separator with a magnetic field strength of 120KA / m~165KA / m; scavenging II is a drum magnetic separator with a magnetic field strength of 350KA / m~500KA / m; high-frequency screening uses a five-layer high-frequency screen with a screen aperture of 0.1mm.

4. The method as described in claim 1, characterized in that: In step S5b, the third hydraulic stage uses a hydrocyclone with a diameter of 500 mm, a sand discharge nozzle diameter of 80 mm, and an operating pressure of 0.08 MPa to 0.11 MPa; in step S5c, the fourth hydraulic stage uses a hydrocyclone with a diameter of 100 mm, a sand discharge nozzle diameter of 20 mm, and an operating pressure of 0.08 MPa to 0.11 MPa; the fifth hydraulic stage uses a hydrocyclone with a diameter of 350 mm, a sand discharge nozzle diameter of 70 mm, and an operating pressure of 0.18 MPa to 0.25 MPa.

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