A beneficiation method for improving the concentrate grade of hematite-hematitite ore and reducing the silicon content

Abstract

The application discloses a beneficiation method for improving the concentrate grade of hematite-limonite and reducing the silicon content, and belongs to the technical field of mineral processing engineering. On the basis of two-stage screening and crushing, two-stage groove type ore washing and spiral grading scrubbing, modified composite scrubbing reagents and adaptive reagent systems are introduced, through the synergistic effect of dispersion and gel breaking, chelation and stable effect, selective silicon inhibition and double-layer anti-mudding, the separation of mud and sand and the separation of iron and silicon are strengthened. The reagent is compounded by sodium hexametaphosphate, amine-modified water glass, sodium carboxymethyl cellulose-hydroxypropyl methyl cellulose and sodium citrate-sodium pyrophosphate, and is added in stages and activated at constant temperature, and is deeply coupled with the existing equipment parameters. The main equipment does not need to be transformed, the reagent consumption is small, the cost is low, and the application is green and environment-friendly. Good product improvement and silicon reduction indexes can be obtained, and the application is suitable for product improvement and silicon reduction of the Dahongshan type refractory hematite-limonite and high-mud and easy-mudding metallic ore, and has remarkable industrialization popularization value.

Description

Technical Field

[0001] This invention relates to the field of mineral processing engineering technology, specifically to a beneficiation method for improving the grade of hematite concentrate and reducing its silicon content. Background Technology

[0002] Hematite is a natural mixture of multiple minerals, mainly composed of hydrated iron oxide, with FeO(OH) as its primary component. nH2O is a weakly magnetic, finely disseminated, easily muddy, and difficult-to-process mineral. my country has nearly 10 billion tons of hematite reserves, with enormous development and utilization value. However, existing separation processes have significant drawbacks: While high-intensity magnetic separation can increase concentrate grade by reducing the magnetic field strength, it results in high tailings grade and significant iron loss; conversely, increasing the magnetic field strength leads to lower iron concentrate grade, making it impossible to balance grade and recovery rate. The combined roasting magnetic separation-high-intensity magnetic separation-flotation process involves large investments, high production costs, unstable indicators, and significant environmental pressures, making long-term stable industrial operation difficult.

[0003] For example, the Dahongshan-type hematite exhibits significant differences in crystal structure among different phases, making it a polycrystalline hematite. The same grade of hematite is composed of multiple hematite crystal forms, resulting in hematite with different structures. Three main crystal systems exist: hexagonal (simple trigonal space group, cell parameters 5.0356 x 5.0356 x 13.7489), cubic (cell parameters 8.3515 x 8.3515 x 8.3515), and tetragonal (body-centered orthorhombic space group, cell parameters 8.34 x 8.34 x 25.02). During mineralization and alteration, differentiated iron mineral crystal structures are formed. Hematite with the same chemical formula exhibits different crystal geometry and electromagnetic structures, leading to differences in magnetic separation of crystals formed at different alteration stages. Therefore, this portion of hematite is difficult to recover efficiently using a single magnetic separation method. Furthermore, open-pit mining during the rainy season results in a mud content as high as 18%, containing iron silicate minerals with high magnetic properties, leading to extremely poor performance of conventional magnetic separation. Conventional washing and scrubbing processes suffer from incomplete mud-sand separation, low removal rate of siliceous gangue, and easy loss of iron ore particles through mudification, limiting the effectiveness of grade improvement and silica reduction. These problems hinder the efficient utilization of hematite, resulting in low-grade iron concentrate, high silica content, and low recovery rates, thus restricting the large-scale development of this type of difficult-to-process iron ore resource.

[0004] Therefore, it is of great significance to develop a process for efficient extraction, deep desiliconization, and high recovery rate of polycrystalline coexisting hematite. Summary of the Invention

[0005] To address the problems of incomplete desliming, low concentrate grade, poor silica reduction, easy mudification and loss of iron ore, high cost, and unstable indicators in the beneficiation process of hematite, the purpose of this invention is to provide a beneficiation method that improves the grade of hematite concentrate and reduces its silica content, specifically including the following steps: S1: The raw ore is pre-screened, coarsely crushed, pre-screened and inspected, and finely crushed, and then combined with the undersize particles to obtain pulverized material.

[0006] S2: The crushed material is sequentially fed into two trough washing tanks. Modified composite hematite scrubbing agent is added to each trough washing tank in sequence, and constant temperature activation is carried out to obtain scrubbing slurry.

[0007] S3: The scrubbed slurry is classified by spiral classifier (the reagents continue to act during the spiral classification process) to obtain overflow and underflow. The underflow enters the grinding-classification operation (the ball mill and hydrocyclone form a closed circuit); the product of the grinding-classification operation (hydrocyclone overflow) is subjected to gravity separation by shaking table to obtain iron concentrate and tailings.

[0008] Preferably, the modified composite hematite scrubbing agent in step S2 of the present invention comprises: sodium hexametaphosphate, amination-modified water glass, anti-mudification compound, and chelating compound, wherein the mass ratio of sodium hexametaphosphate, amination-modified water glass, anti-mudification compound, and chelating compound is 40~50:15~25:5~10:10~15; more preferably, the mass ratio of sodium hexametaphosphate, amination-modified water glass, anti-mudification compound, and chelating compound is 50:25:10:15.

[0009] Preferably, the anti-mudification compound of the present invention comprises sodium carboxymethyl cellulose and hydroxypropyl methylcellulose, wherein the mass ratio of sodium carboxymethyl cellulose to hydroxypropyl methylcellulose is 5~7:1~3; more preferably, the mass ratio of sodium carboxymethyl cellulose to hydroxypropyl methylcellulose of the present invention is 7:3.

[0010] Preferably, the chelating compound of the present invention comprises sodium citrate and sodium pyrophosphate, wherein the mass ratio of sodium citrate to sodium pyrophosphate is 1:1.

[0011] Preferably, the total amount of modified composite hematite scrubbing agent used in step S2 of the present invention is 45~75g / t, and the mass ratio of the agent added in stage I and stage II is 3:2.

[0012] Preferably, the conditions for constant temperature activation in step S2 of the present invention are: the conditions for stage I ore washing are constant temperature activation at 35~45℃ for 8~10 minutes, and the conditions for stage II ore washing are constant temperature activation at 30~40℃ for 6~8 minutes.

[0013] Preferably, the maximum particle size of the hydrocyclone overflow in step S3 of the present invention is ≤0.038 mm.

[0014] Preferably, in step S3 of the present invention, the fineness of the underwash grinding is -0.074 mm, accounting for 80% to 90%.

[0015] Preferably, the conditions for the shaking table gravity separation in step S3 of the present invention are: slurry mass concentration of 25%~30%, transverse slope of the bed surface of 1.5°~2.5°, stroke of 12~16 mm, stroke rate of 280~320 times / min, and bed flushing water flow rate of 1.2~1.8 m³ / h.

[0016] This invention provides a mineral processing method for improving the grade of hematite and reducing its silicon content, which has the following beneficial effects: (1) This invention addresses the common industry problems of fine-grained dissemination, high mud content, easy mud formation, and difficulty in removing siliceous gangue in hematite. It achieves a synergistic effect of dispersion and degelatination, chelation and stabilization, selective silicon inhibition, and double-layer anti-mud formation through an integrated process of two-stage screening and crushing + two-stage washing agent enhanced scrubbing + spiral classification and continued scrubbing + ball milling classification + shaking table gravity separation, combined with modified composite scrubbing agent and precise agent system.

[0017] (2) Compared with traditional strong magnetic separation, roasting magnetic separation, and conventional washing and scrubbing processes, this invention can purify difficult-to-process hematite with TFe 35%~38% and SiO2 12%~16% in the raw ore to concentrate TFe≥55% and SiO2≤5.5%, with a stable iron recovery rate ≥87%. It completely solves the pain points of traditional processes, such as difficulty in balancing grade and recovery rate, incomplete desliming and silicon reduction, and easy mudification and loss of iron minerals. It provides an efficient, stable, and low-cost industrial-scale process for upgrading and reducing silicon content of high-mud and high-silicon hematite of the Dahongshan type and similar easily mud-forming metal ores.

[0018] (3) This invention protects iron minerals from being lost through grinding by using a double-layer anti-mudification component. The segmented addition of chemicals and constant temperature activation are suitable for low / medium / high mud and high silica raw ores and low temperature working conditions, making it more targeted for complex crystal system hematite of the Dahongshan type.

[0019] (4) The method of the present invention has no high energy consumption and high pollution links such as roasting and flotation. The process is short, easy to operate and stable. The reagents are non-toxic, free of heavy metals and secondary pollution. The return water can be circulated in a closed loop. It is suitable for long-term continuous industrial production. There is no need to replace the main mineral processing equipment. Only the reagent addition system needs to be added to implement it. It is compatible with existing mineral processing production lines and has a low threshold for industrial promotion. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the mineral processing flow of the present invention. Detailed Implementation

[0021] 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.

[0022] In the embodiments and comparative examples of this invention, the reagents are added in solution form, and the amount is based on solute.

[0023] The preparation method of the amination-modified water glass of the present invention is as follows: Select industrial water glass with a modulus of 2.4 to 2.8, dilute with water to prepare a water glass solution with a mass concentration of 30%, stir and heat to 60 °C; slowly add diethylenetriamine, the amount of diethylenetriamine added is 4% of the mass of water glass solid, keep at a constant temperature and stir for 2 h; after stirring is completed, cool naturally and let stand for aging for 12 h to obtain the amination-modified water glass mother liquor for later use.

[0024] The specific preparation method of the modified composite hematite scrubbing agent in this invention is as follows: (1) Sodium hexametaphosphate, amination-modified water glass, sodium carboxymethyl cellulose, hydroxypropyl methyl cellulose, sodium citrate and sodium pyrophosphate were dried at 45±5 ℃ for 2 h to completely remove free water and avoid clumping that would affect the dissolution and compounding effect.

[0025] (2) Dissolve sodium hexametaphosphate in water to prepare a sodium hexametaphosphate solution; dissolve aminated water glass in water to prepare an aminated water glass solution; dissolve sodium citrate and sodium pyrophosphate in water to prepare a chelated compound solution; dissolve sodium carboxymethyl cellulose and hydroxypropyl methyl cellulose in water to prepare an anti-mudification compound solution; dissolve each solution during preparation, and there is no concentration requirement (the solution used in the embodiments and comparative examples of this invention has a mass percentage concentration of 10%).

[0026] (3) Control the temperature at 40±5 ℃, mix sodium hexametaphosphate solution, chelated compound solution and amination modified water glass solution in sequence, and stir evenly; cool down to 30±5 ℃, add anti-mudification compound solution, and continue to stir evenly to obtain a mixture, namely modified composite hematite scrubbing agent; seal and store away from light, and it will remain stable and effective within 25 to 35 days.

[0027] The sodium carboxymethyl cellulose used in this invention is low-viscosity sodium carboxymethyl cellulose: when the mass percentage concentration is 2% aqueous solution, the viscosity is 200-800 mPa·s, and the industrial grade has a degree of polymerization of 100-2000.

[0028] In the embodiments of this invention, the mass ratio of sodium hexametaphosphate, amination-modified water glass, anti-mudification compound, and chelate compound in the modified composite hematite scrubbing agent is 50:25:10:15; the mass ratio of sodium carboxymethyl cellulose and hydroxypropyl methyl cellulose is 7:3; and the mass ratio of sodium citrate and sodium pyrophosphate is 1:1.

[0029] Example 1 A beneficiation method for improving the grade of hematite concentrate and reducing silicon content, for conventional argillaceous hematite (Dahongshan type hematite: TFe 36.47%, SiO2 13.42%, mud content 25%), the beneficiation process is as follows: Figure 1 As shown, the specific steps include: S1: The raw ore is unloaded into a 200×200 bar screen (pre-screening) by a mining truck. The material on the screen enters a PE400×600 jaw crusher for coarse crushing, and then passes through a 150×150 grid screen for further screening (pre-screening and inspection screening). The material on the screen then enters a PEX250×1000 jaw crusher for fine crushing. After fine crushing, the ore and the undersize particles are combined to obtain the crushed material.

[0030] S2: The crushed material is sequentially fed into a 1500×7500 trough washing machine (stage I washing) and a 1200×600 trough washing machine (stage II washing). Modified composite hematite scrubbing agent (hereinafter referred to as agent) is added in stages. The total amount of agent is 50g / t. In stage I washing, the amount of agent is 30g / t, which is activated at a constant temperature of 40℃ for 8 minutes. In stage II washing, the amount of agent is 20g / t, which is activated at a constant temperature of 35℃ for 6 minutes to obtain scrubbing slurry.

[0031] S3: The scrubbing slurry enters the FG-Ø1500 spiral classifier for classification (the reagents continue to act during the spiral classification process, and the duration of the reagent action is ≥5min), resulting in overflow and underflow. The underflow enters the grinding-classification operation (a closed circuit consisting of a ball mill and a hydrocyclone), where the grinding fineness is -0.074mm, accounting for 90%. The product of the grinding-classification operation (hydrocyclone overflow) is subjected to gravity separation by a shaking table to obtain iron concentrate and tailings. The return water is circulated in a closed circuit, and the fine mud is dry-piled.

[0032] Example 2 A beneficiation method for improving the grade of hematite concentrate and reducing its silicon content, specifically for high-mud, high-silicon hematite (Dahongshan type hematite: TFe 35.82%, SiO2 15.63%, mud content 40%), includes the following steps: S1: The raw ore is unloaded into a 200×200 bar screen (pre-screening) by a mining truck. The material on the screen enters a PE400×600 jaw crusher for coarse crushing, and then passes through a 150×150 grid screen for further screening (pre-screening and inspection screening). The material on the screen then enters a PEX250×1000 jaw crusher for fine crushing. After fine crushing, the ore and the undersize particles are combined to obtain the crushed material.

[0033] S2: The crushed material is sequentially fed into a 1500×7500 trough washing machine (stage I washing) and a 1200×600 trough washing machine (stage II washing). Modified composite hematite scrubbing agent is added in stages, with a total dosage of 75g / t. The dosage of agent in stage I washing is 45g / t, and it is activated at a constant temperature of 45℃ for 10 minutes. The dosage of agent in stage II washing is 30g / t, and it is activated at a constant temperature of 40℃ for 8 minutes to obtain scrubbing slurry.

[0034] S3: The scrubbing slurry enters the FG-Ø2000 spiral classifier for classification (the reagents continue to act during the spiral classification process, and the duration of the reagent action is ≥5min), resulting in overflow and underflow. The underflow enters the grinding-classification operation (a closed circuit consisting of a ball mill and a hydrocyclone), where the grinding fineness is -0.074mm, accounting for 80%. The product of the grinding-classification operation (hydrocyclone overflow) is subjected to gravity separation by a shaking table to obtain iron concentrate and tailings. The return water is circulated in a closed circuit, and the fine mud is dry-piled.

[0035] Example 3 A beneficiation method for improving the grade of hematite concentrate and reducing its silicon content, specifically for low-mud, low-silicon hematite (Dahongshan type hematite: TFe 37.25%, SiO2 12.86%, mud content 20%), includes the following steps: S1: The raw ore is unloaded into a 200×200 bar screen (pre-screening) by a mining truck. The material on the screen enters a PE400×600 jaw crusher for coarse crushing, and then passes through a 150×150 grid screen for further screening (pre-screening and inspection screening). The material on the screen then enters a PEX250×1000 jaw crusher for fine crushing. After fine crushing, the ore and the undersize particles are combined to obtain the crushed material.

[0036] S2: The crushed material is sequentially fed into a 1500×7500 trough washing machine (stage I washing) and a 1200×600 trough washing machine (stage II washing). Modified composite hematite scrubbing agent is added in stages, with a total dosage of 45g / t. The dosage of agent in stage I washing is 27g / t, and it is activated at a constant temperature of 35℃ for 8 minutes. The dosage of agent in stage II washing is 18g / t, and it is activated at a constant temperature of 30℃ for 6 minutes to obtain scrubbing slurry.

[0037] S3: The scrubbing slurry enters the FG-Ø1500 spiral classifier for classification (the reagents continue to act during the spiral classification process, and the reagents continue to act for ≥5 minutes), resulting in overflow and underflow. The underflow enters the grinding-classification operation (a closed circuit consisting of a ball mill and a hydrocyclone), and the grinding fineness is -0.074mm, accounting for 88%. The product of the grinding-classification operation (hydrocyclone overflow) is subjected to gravity separation by a shaking table to obtain iron concentrate and tailings. The return water is circulated in a closed circuit, and the fine mud is dry-piled.

[0038] Example 4 A beneficiation method for improving the grade of hematite concentrate and reducing its silicon content, specifically for medium-sludge, medium-silica hematite (Dahongshan type hematite: TFe 36.10%, SiO2 14.25%, mud content 35%), includes the following steps: S1: The raw ore is unloaded into a 200×200 bar screen (pre-screening) by a mining truck. The material on the screen enters a PE400×600 jaw crusher for coarse crushing, and then passes through a 150×150 grid screen for further screening (pre-screening and inspection screening). The material on the screen then enters a PEX250×1000 jaw crusher for fine crushing. After fine crushing, the ore and the undersize particles are combined to obtain the crushed material.

[0039] S2: The crushed material is sequentially fed into a 1500×7500 trough washing machine (stage I washing) and a 1200×600 trough washing machine (stage II washing). Modified composite hematite scrubbing agent is added in stages, with a total dosage of 65g / t. The dosage of agent in stage I washing is 39g / t, and it is activated at a constant temperature of 42℃ for 9 minutes. The dosage of agent in stage II washing is 26g / t, and it is activated at a constant temperature of 36℃ for 7 minutes to obtain scrubbing slurry.

[0040] S3: The scrubbing slurry enters the FG-Ø1500 spiral classifier for classification (the reagents continue to act during the spiral classification process, and the duration of the reagent action is ≥5min), resulting in overflow and underflow. The underflow enters the grinding-classification operation (a closed circuit consisting of a ball mill and a hydrocyclone), where the grinding fineness is -0.074mm, accounting for 82%. The product of the grinding-classification operation (hydrocyclone overflow) is subjected to gravity separation by a shaking table to obtain iron concentrate and tailings. The return water is circulated in a closed circuit, and the fine mud is dry-piled.

[0041] Example 5 A beneficiation method for improving the grade of hematite concentrate and reducing silicon content, specifically for medium-low mud hematite (Dahongshan type hematite: TFe 36.78%, SiO2 13.96%, mud content 30%), includes the following steps: S1: The raw ore is unloaded into a 200×200 bar screen (pre-screening) by a mining truck. The material on the screen enters a PE400×600 jaw crusher for coarse crushing, and then passes through a 150×150 grid screen for further screening (pre-screening and inspection screening). The material on the screen then enters a PEX250×1000 jaw crusher for fine crushing. After fine crushing, the ore and the undersize particles are combined to obtain the crushed material.

[0042] S2: The crushed material is sequentially fed into a 1500×7500 trough washing machine (stage I washing) and a 1200×600 trough washing machine (stage II washing). Modified composite hematite scrubbing agent is added in stages, with a total dosage of 45g / t. The dosage of agent in stage I washing is 27g / t, and it is activated at a constant temperature of 35℃ for 8 minutes. The dosage of agent in stage II washing is 18g / t, and it is activated at a constant temperature of 30℃ for 6 minutes to obtain scrubbing slurry.

[0043] S3: The scrubbing slurry enters the FG-Ø1500 spiral classifier for classification (the reagents continue to act during the spiral classification process, and the duration of the reagent action is ≥5min), resulting in overflow and underflow. The underflow enters the grinding-classification operation (a closed circuit consisting of a ball mill and a hydrocyclone), where the grinding fineness is -0.074mm, accounting for 86%. The product of the grinding-classification operation (hydrocyclone overflow) is subjected to gravity separation by a shaking table to obtain iron concentrate and tailings. The return water is circulated in a closed circuit, and the fine mud is dry-piled.

[0044] Comparative Example 1 The difference between this comparative example and Example 1 is that in step S2, only a 1500×7500 tank washing machine in section I is used for washing the ore, and the reagent is added at a time in the amount of 50g / t. All other steps are the same.

[0045] Comparative Example 2 The difference between this comparative example and Example 2 is that only sodium hexametaphosphate is added to the reagent, while the other steps are the same.

[0046] Comparative Example 3 The difference between this comparative example and Example 3 is that only aminated modified water glass is added to the reagent, while the other steps are the same.

[0047] Comparative Example 4 The difference between this comparative example and Example 4 is that only the chelating compound is added to the pharmaceutical preparation, while the other steps are the same.

[0048] Comparative Example 5 The difference between this comparative example and Example 5 is that only the anti-mudification compound is added to the reagent, while the other steps are the same.

[0049] The mineral processing indicators of Examples 1-5 and Comparative Examples 1-5 of the present invention are shown in Table 1 below.

[0050] Table 1 As can be seen from the table above, this invention, based on comprehensively enhancing process advantages, employs a four-component synergistic compound reagent system. Through the synergistic effects of dispersion and degumming, chelation and stabilization, selective silicon inhibition, and double-layer anti-sludge formation, it solves the problems of high mud content, easy mud formation, and difficult silicon removal in hematite. Single-component reagents cannot simultaneously achieve multiple functions such as degumming, silicon inhibition, anti-sludge formation, and stabilization. However, the compound reagent of this invention, through multi-component functional complementarity, segmented activation, and synergistic effects, strengthens the separation process from multiple dimensions such as interface modification, slurry regulation, and mineral protection, ultimately achieving the integrated beneficiation goal of complete separation of mud and sand, efficient iron-silicon separation, concentrate upgrading and silicon reduction, and high recovery rate.

[0051] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A mineral processing method for improving the grade of hematite concentrate and reducing its silicon content, characterized in that, Specifically, the following steps are included: S1: The raw ore is pre-screened, coarsely crushed, pre-screened and inspected, and finely crushed, then combined with the undersize particles to obtain pulverized material; S2: The crushed material is sequentially fed into two trough washing operations. Modified composite hematite scrubbing agent is added to each trough washing operation in sequence and activated at a constant temperature to obtain scrubbing slurry. S3: The scrubbed slurry is classified by spiral classifier to obtain overflow and underfill. The underfill enters the grinding-classification operation. The product of the grinding-classification operation is subjected to gravity separation by shaking table to obtain iron concentrate and tailings.

2. The beneficiation method for improving the grade of hematite concentrate and reducing silicon content according to claim 1, characterized in that, The modified composite hematite scrubbing agent mentioned in step S2 includes: sodium hexametaphosphate, amination-modified water glass, anti-mudification compound and chelate compound, wherein the mass ratio of sodium hexametaphosphate, amination-modified water glass, anti-mudification compound and chelate compound is 40~50:15~25:5~10:10~15.

3. The beneficiation method for improving the grade of hematite concentrate and reducing silicon content according to claim 2, characterized in that, The anti-mudification compound includes sodium carboxymethyl cellulose and hydroxypropyl methylcellulose, wherein the mass ratio of sodium carboxymethyl cellulose to hydroxypropyl methylcellulose is 5~7:1~3; the chelating compound includes sodium citrate and sodium pyrophosphate, wherein the mass ratio of sodium citrate to sodium pyrophosphate is 1:

1.

4. The beneficiation method for improving the grade of hematite concentrate and reducing silicon content according to claim 1, characterized in that, The total amount of the modified composite hematite scrubbing agent mentioned in step S2 is 45~75g / t, and the mass ratio of the agent added in stage I and stage II is 3:

2.

5. The beneficiation method for improving the grade of hematite concentrate and reducing silicon content according to claim 1, characterized in that, The conditions for constant temperature activation in step S2 are as follows: for stage I ore washing, the conditions are constant temperature activation at 35~45℃ for 8~10 minutes, and for stage II ore washing, the conditions are constant temperature activation at 30~40℃ for 6~8 minutes.

6. The beneficiation method for improving the grade of hematite concentrate and reducing silicon content according to claim 1, characterized in that, The maximum particle size of the hydrocyclone overflow in step S3 is ≤0.038 mm.

7. The beneficiation method for improving the grade of hematite concentrate and reducing silicon content according to claim 1, characterized in that, In step S3, the fineness of the underground sand grinding is -0.074 mm, accounting for 80% to 90%.

8. The beneficiation method for improving the grade of hematite concentrate and reducing silicon content according to claim 1, characterized in that, The conditions for the shaking table gravity separation described in step S3 are: slurry mass concentration of 25%~30%, transverse slope of the bed surface of 1.5°~2.5°, stroke of 12~16 mm, stroke rate of 280~320 times / min, and bed flushing water flow rate of 1.2~1.8 m³ / h.

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