Method for extracting high-grade high-quality lead-zinc ore from lead-zinc tailings by adopting gravity concentration equipment

Abstract

The invention relates to the technical field of lead-zinc ore extraction metallurgy, and particularly discloses a method for extracting high-grade high-quality lead-zinc ore from lead-zinc tailings by adopting gravity concentration equipment. The composition comprises a bio-based zwitterionic polymer solution serving as a heavy medium carrier, and the bio-based zwitterionic polymer solution is formed by compounding a biodegradable anionic polysaccharide derivative and a quaternized vegetable gum cationic modifier; the product is dehydrated concentrate with the total grade of lead and zinc being greater than or equal to 65%. The preparation method comprises the following steps: pre-treating raw materials and screening target particle swarms; multi-stage reselection and enrichment are combined with gradient acid leaching for impurity removal; recycling the micro-fine particles in different paths; and carrying out heavy medium final selection upgrading and closed-loop water circulation. The composition disclosed by the invention forms a stable suspension system through the synergistic effect of zwitterions, and adapts to the rheological property of the magnetically-stabilized heavy fluid; according to the preparation method, precise regulation and control of the flow velocity gradient of the ore pulp are achieved through vibration shaking table gradient partition, pulsed magnetic field dissociation and rotational flow-centrifugal path division treatment, and the preparation method has the advantages of being good in environment compatibility, high in granularity adaptability and controllable in resource consumption.

Description

Technical Field

[0001] This application relates to the field of metallurgical technology for lead-zinc ore extraction, and more specifically, to a method for extracting high-grade, high-quality lead-zinc ore from lead-zinc tailings using gravity separation equipment. Background Technology

[0002] Lead-zinc tailings are solid waste residues remaining after physical beneficiation of lead-zinc ore. They contain 5-15% residual lead-zinc minerals and associated valuable metals such as silver and cadmium. As strategic mineral resources, lead is widely used in batteries, radiation protection, and special alloys, while zinc is a key raw material for galvanized steel, metal corrosion protection, and the pharmaceutical industry. With the continuous decline in global lead-zinc ore grades, the recoverable amount of lead and zinc in tailings is equivalent to the reserves of 200 medium-sized mines. Meanwhile, the demand for high-quality lead-zinc ore, as an essential raw material for high-energy battery electrode materials and special alloys for national defense and military industries, is growing at an annual rate of 12%.

[0003] In the field of lead-zinc tailings recovery, the conventional gravity-magnetic separation combined process has a core technical defect of inaccurate control of slurry flow rate gradient. The single slope design of the vibrating shaker leads to insufficient difference in slurry flow rate between coarse and fine particle zones, weakening the migration dynamics of heavy minerals. At the same time, the weak magnetic field cannot dissociate fine intergrowths, and the smooth inner wall structure of the spiral chute causes turbulence interference. Under weak magnetic field conditions, the dissociation efficiency of fine intergrowths is limited. The mixed treatment of tailings of different particle sizes causes material compatibility conflicts, which in turn affects the effectiveness of the separation process. Summary of the Invention

[0004] To address the problem of low separation efficiency of coarse and fine particles caused by inaccurate control of slurry flow rate gradient in existing technologies, this application provides a method for extracting high-grade fine lead-zinc ore from lead-zinc tailings using gravity separation equipment.

[0005] A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment includes the following steps: S1. Raw material pretreatment: The lead-zinc tailings are crushed to a particle size of ≤5mm, and the target particle group with a particle size of 0.075mm to 2mm is separated by screening. The material on the screen is returned to the crushing process. S2, Multi-stage reselection enrichment: S2.1. A composite spiral sluice is used to rough the target particle group. The sluice inclination angle is controlled between 14° and 18°, and the flushing water pressure is controlled between 0.8 and 1.2 MPa to obtain a rough concentrate. S2.2. Input the rough concentrate into a centrifuge with backwash water regulation function for primary cleaning, with a centrifugal force intensity of 200 to 350G and a backwash water flow rate of 30 to 50L / min; S2.3 The primary selected product enters a vibrating shaker for secondary selection, wherein the slope of the coarse selection zone is 2.5° to 3.5°, the slope of the selection zone is 0.5° to 1.5°, the amplitude is 8 to 12 mm, and the stroke rate is 250 to 350 times / minute. S3. Magnetoelectric Co-processing Impurity Removal: The product from the secondary selection is crushed to 0.1-0.3mm, then classified by a hydrocyclone, and the underflow enters a high-intensity magnetic separator for impurity removal under a background field strength of 0.8-1.2T superimposed pulsed magnetic field. S4. Fine particle recovery: The centrifugal tailings from step S2.2 are directly fed into a cyclone-centrifugal coupling device containing an acoustic wave transmitter. The magnetic separation tailings from step S3 are fed in after being regrinded to 0.043-0.074mm. The cone angle of the cyclone is 15° to 20° and the ultrasonic frequency is 28 to 40kHz. S5. Product quality improvement: The concentrates obtained from S2.3, S3 and S4 are combined and the final separation is carried out using a heavy medium separator. The heavy medium is a magnetically stable heavy liquid. S6. Concentrate dewatering: The concentrate obtained in step S5 is dewatered by two-stage vacuum filtration to obtain dewatered lead-zinc concentrate with a moisture content of ≤15%. S7. Filter water circulation: Input the filtered water produced by dehydration into the inclined plate sedimentation tank.

[0006] By adopting the above technical solutions, the crushing and screening particle size control achieves mineral liberation and particle size classification, thereby eliminating interference from excessively coarse particles and deterioration of the flow state by excessively fine sludge; the coordinated control of inclination angle and water pressure enhances the slurry shear rate, thereby improving the initial separation accuracy of light and heavy minerals; the dynamic adjustment of backwash water to match centrifugal force balances particle settling and bed loosening, thereby preventing mechanical inclusion of heavy minerals; the slope of the coarsening zone accelerates particle transport, and the slope of the cleaning zone extends the separation path, thereby constructing a gradient velocity field, thereby simultaneously optimizing coarse particle settling and fine particle recovery; and the background field strength captures weakly magnetic gangue, and the pulsed magnetic field periodically dissolves... The separation of agglomerates dynamically regulates magnetization, thereby suppressing grade loss caused by magnetic agglomeration. By directly processing coarse particles with centrifugal tailings and regrinding fine particles with magnetic tailings, the separate input paths isolate particle size-density interference effects, thus improving the separation accuracy of the cyclone-centrifugal coupling device. Magnetically stabilized heavy liquid constructs a stable density field, achieving ultimate separation of lead-zinc minerals from residual gangue. Two-stage vacuum gradient dewatering progressively reduces filter cake porosity, meeting the moisture content requirements for industrial transportation. Gravity settling in the inclined plate sedimentation tank facilitates natural solid-liquid interface separation, maintaining a closed-loop circulation of the process water system.

[0007] Preferably, in step S1, the screening and separation adopts a three-layer stepped vibrating screen with screen mesh numbers of 20 mesh, 80 mesh and 200 mesh, and a vibration frequency of 1800 to 2400 rpm.

[0008] By adopting the above technical solution, the gradient arrangement of 20-mesh, 80-mesh, and 200-mesh screens can intercept particles of different sizes step by step, thereby eliminating the wear of coarse particles on the sorting equipment, preventing the deterioration of the slurry flow state by sludge, and thus achieving the effect of accurately locking the target particle size; the variable frequency excitation force adjustment can dynamically optimize the particle screening behavior.

[0009] Preferably, in step S2.1, the trapezoidal groove of the composite spiral chute has a depth of 0.5 to 1.0 mm and a groove spacing of 3 to 5 mm.

[0010] By adopting the above technical solution, the trapezoidal groove structure with a depth of 0.5 to 1.0 mm plays a role in guiding the slurry to form a laminar flow state. The geometric constraint effect of the groove sidewall on the slurry flow is used to weaken the generation of turbulent vortices. By maintaining a groove spacing of 3 to 5 mm, the movement trajectory of mineral particles is controlled, ensuring that the particles are controlled by the combined shear force and gravity in the channel.

[0011] Preferably, in step S2.2, the backwash water flow rate is dynamically adjusted according to the slurry density inside the centrifuge.

[0012] By adopting the above technical solution, the backwash water flow rate is dynamically adjusted according to the slurry density, which can be used to adapt to the rheological characteristics of the slurry in real time. When the slurry density increases, the backwash water flow rate is increased to enhance the shear thinning effect of the fluid. When the density decreases, the flow rate is reduced to maintain the suspension stability of the mineral particles in the centrifugal field.

[0013] Preferably, in step S3, the strong magnetic separator adopts a vertical ring magnetic system with a pulse magnetic field peak intensity of 1.2-1.8T.

[0014] By adopting the above technical solution, the vertical ring-shaped magnetic system structure is used to construct an axisymmetric closed magnetic circuit, eliminating the magnetic field line attenuation region of the traditional horizontal magnetic system and ensuring the homogeneity and gradient continuity of the magnetic field spatial distribution. By applying a pulsed magnetic field peak intensity of 1.2-1.8T, a high-frequency eddy current is excited, and the transient Lorentz force generated by the pulse rising edge is used to directionally impact the mineral intergrowth interface, overcoming the hysteresis effect of the steady-state magnetic field.

[0015] Preferably, in step S5, the heavy liquid is a solid-liquid suspension system composed of ultrafine magnetite powder and an organic carrier, wherein the magnetite powder has a particle size ≤5μm, and the suspension stability is maintained by mechanical stirring.

[0016] By adopting the above technical solution, the use of ultrafine magnetite powder with a particle size ≤5μm increases the specific surface area of ​​the particles; and by maintaining the suspension system through mechanical stirring, continuous shear stress is applied.

[0017] Preferably, the organic carrier is a bio-based zwitterionic polymer solution, consisting of the following components: 1.5-3.0 wt% biodegradable anionic polysaccharide derivative; 0.2-0.8 wt% quaternized plant gum cationic modifier; and the balance being water.

[0018] By adopting the above technical solution, 1.5-3.0 wt% of biodegradable anionic polysaccharide derivatives are used to construct a steric hindrance layer. The negatively charged groups of its polymer chain repel magnetite powder particles, and the hard agglomeration driven by van der Waals attraction is suppressed by electrostatic repulsion. By introducing 0.2-0.8 wt% of quaternized plant gum cationic modifier, it plays a role in charge compensation and bridging stability. The cationic quaternary ammonium groups partially neutralize the negative charge on the particle surface, and its long-chain polysaccharide structure penetrates the adjacent double layer to form a flexible connecting bridge.

[0019] Preferably, in step S7, after the sedimentation tank has been in the sedimentation tank for 30 to 60 minutes, the supernatant is returned to step S2.1 as rinsing water for reuse.

[0020] By adopting the above technical solution, the retention time of the filtered water in the sedimentation tank is controlled to 30 to 60 minutes, which fully realizes the effect of gravity sedimentation. Stokes' law is used to enable the suspended solids to complete solid-liquid separation in the laminar flow zone. The lower limit of the time ensures that particles ≥10μm settle completely, while the upper limit avoids excessive retention that would lead to colloid resuspension. By returning the supernatant as rinsing water to step S2.1, a closed-loop water circulation is constructed. By utilizing the difference in interface characteristics between the flocculated phase and the aqueous phase, reclaimed water with a turbidity ≤10NTU is separated.

[0021] Preferably, in step S4, the centrifugal unit of the cyclone-centrifugal coupling device is a horizontal screw discharge centrifuge with a differential speed of 8-12 rpm.

[0022] By adopting the above technical solution, and controlling the differential speed of the horizontal screw discharge centrifuge within the range of 8-12 rpm, a dynamic balance between axial transport and radial settling in the swirling flow field is constructed: the differential speed of 8 rpm provides critical shear force to block the liquid bridge agglomeration of fine minerals; the differential speed of 12 rpm is adapted to the Stokes settling time and the screw torque cycle, forming a dual mechanism of continuous axial slag discharge and radial laminar flow stability. At the same time, the secondary circulation induced by the differential speed gradient enhances the Magnus effect, realizing the targeted capture of micro-particles.

[0023] Preferably, in step S6, the vacuum degree of the first-stage filtration dewatering is -0.06 to -0.08 MPa, and the vacuum degree of the second-stage filtration is -0.08 to -0.1 MPa.

[0024] By adopting the above technical solution, the first-stage filtration vacuum degree is set to -0.06 to -0.08 MPa, which breaks down the capillary resistance of the filter cake. The initial adhesion energy barrier at the liquid-solid interface is overcome by using a moderate negative pressure environment, thus achieving primary separation of free water and bound water. The second-stage filtration vacuum degree is increased to -0.08 to -0.1 MPa, which enhances the dehydration of the filter cake pores. The high-pressure gradient difference is used to destroy the colloidal hydration membrane and release the bound water in the mineral lattice gaps.

[0025] In summary, this application has the following beneficial effects: 1. Because this application adopts differentiated settings of the slope of the coarse selection zone and the fine selection zone of the vibrating shaking table, and combines the background field strength superimposed with the pulse magnetic field design of the vertical ring magnetic system, and at the same time with the trapezoidal groove structure of the composite spiral chute, the precise control effect of the slurry velocity gradient in the mineral separation process is achieved, thereby eliminating the disordered entrainment of mineral particles caused by turbulence interference from the root, and providing a fluid dynamic calibration guarantee for the separation accuracy.

[0026] 2. In this application, a separate processing strategy of centrifugal tailings and magnetic separation tailings is preferred, and differential speed control of a horizontal screw discharge centrifuge is configured. At the same time, a bio-based heavy medium system maintained by mechanical stirring is combined to achieve the effect of targeted separation of fine particles and enhanced medium stability.

[0027] 3. The method of this application achieves the effect of closed-loop water resource recycling and improved process compatibility by combining the sedimentation and retention of the filter inclined plate with the two-stage vacuum gradient negative pressure dewatering, and coordinating the stepped screening and crushing particle size control links. Attached Figure Description

[0028] Figure 1 This application provides a flowchart of a method for extracting high-grade fine lead-zinc ore from lead-zinc tailings using gravity separation equipment. Detailed Implementation

[0029] The present application will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] Technical concept: In the field of lead-zinc tailings recovery, conventional gravity-magnetic separation processes suffer from three major defects due to inaccurate control of slurry velocity gradient: the single slope of the vibrating shaking table leads to a mismatch in the flow patterns of coarse and fine particles; the smooth inner wall of the spiral chute causes turbulence interference; the dissociation of fine particles is limited under a weak magnetic field; and the mixing of materials of different particle sizes induces compatibility conflicts. These defects directly affect the separation effectiveness.

[0031] This application addresses the above problems through the following solution: Precise flow field control: the slope zoning of the vibrating shaker creates a slurry velocity gradient; the trapezoidal grooves of the composite spiral chute guide and suppress turbulence; and the vertical annular magnetic system superimposed with pulsed magnetic fields generates alternating magnetic lines of force. These three elements work synergistically to optimize the interlayer distribution of minerals. Stable separation of fine particles: centrifugal tailings and magnetic separation tailings are treated separately to match particle size characteristics; differential speed control of the horizontal spiral centrifuge maintains the stability of the swirling flow field; bio-based zwitterionic polymers suppress magnetite powder agglomeration through electrostatic force; and mechanical stirring constructs a low-potential-energy suspended phase. Physical water purification is achieved through gravity sedimentation in the inclined plate sedimentation tank; two-stage vacuum gradient negative pressure dewatering matches the water-holding capacity of the minerals; and stepped screening and pulverization particle size control ensure particle size compatibility throughout the process. All these elements work together to establish a self-balancing water system.

[0032] Preparation Example 1 The preparation method of the bio-based zwitterionic polymer solution is as follows: 100g of konjac glucomannan was added to 500mL of 1.0mol / L sodium hydroxide solution and hydrolyzed at 50°C for 2h with stirring. The hydrolysis product was centrifuged at 3000r / min for 15min. The precipitate was washed with deionized water until neutral and dried under vacuum at 60°C for 8h to obtain deacetylated konjac polysaccharide with a degree of deacetylation ≥85%. The deacetylated konjac polysaccharide was dissolved in 200mL of deionized water, and succinic anhydride was added at a mass ratio of 5:1. The reaction was carried out at pH 8.5 to 9.0 and 70°C for 4h. After cooling, the reaction solution was dialyzed through a dialysis membrane with a molecular weight cutoff of 8000Da for 48h and freeze-dried to obtain a biodegradable anionic polysaccharide derivative with a carboxyl substitution degree of 0.35 to 0.45. 50g of guar gum powder was added to a solution containing 3-chloro-2-hydroxypropyl A mixed solution of 25g of trimethylammonium chloride in ethanol and water (ethanol to water volume ratio 1:1) was prepared, and the pH was adjusted to 10.5 with sodium carbonate. The solution was then etherified at 75°C for 6 hours. The reaction product was precipitated with ethanol and vacuum dried to obtain a quaternized plant gum cationic modifier with a degree of substitution of 0.12 to 0.18. 15g of anionic polysaccharide derivative and 2g of the quaternized plant gum modifier were added to 983g of deionized water and reacted at 40°C with a shear rate of 150s. -1 Stir for 1 hour to obtain a bio-based zwitterionic polymer solution.

[0033] This application provides a method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment. The following details the methods for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment provided in the embodiments of this application.

[0034] Example 1 See attached document Figure 1 A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment includes the following steps: S1. Raw material pretreatment: The lead-zinc tailings are crushed to a particle size of ≤5mm and then passed through a three-stage vibrating screen with a vibration frequency of 2100rpm and screen mesh sizes of 20, 80 and 200 meshes, respectively, to separate the target particle group with a particle size of 0.075mm to 2mm. The material on the screen is returned to the crushing process. S2, Multi-stage reselection enrichment: S2.1. A composite spiral sluice is used to rough the target particle group. The trapezoidal groove of the composite spiral sluice has a depth of 0.7 mm, a groove spacing of 4 mm, a sluice inclination angle of 16°, and a washing water pressure of 1.0 MPa to finally obtain a rough concentrate. S2.2. Input the rough concentrate into a centrifuge with backwash water regulation function for primary cleaning. The centrifugal force intensity is 280G and the backwash water flow rate is 40L / min. The backwash water flow rate is dynamically adjusted according to the slurry density in the centrifuge. S2.3 The primary selected product enters a vibrating shaker for secondary selection, wherein the slope of the coarse selection zone is 3.0°, the slope of the selection zone is 1.0°, the amplitude is 10mm, and the stroke rate is 300 times / minute; S3. Magnetoelectric Co-processing for Impurity Removal: The product from the secondary selection is crushed to 0.2mm, then classified by a hydrocyclone, and the underflow enters a high-intensity magnetic separator for impurity removal under a background field strength of 1.0T superimposed with a pulsed magnetic field. The high-intensity magnetic separator adopts a vertical ring magnetic system with a peak pulsed magnetic field strength of 1.5T. S4. Fine particle recovery: The centrifugal tailings from step S2.2 are directly fed into the cyclone-centrifugal coupling device containing an acoustic transmitter. The magnetic separation tailings from step S3 are fed into the device after being regrinded to 0.058mm. The cyclone cone angle is 18° and the ultrasonic frequency is 35kHz. The centrifugal unit of the cyclone-centrifugal coupling device is a horizontal screw discharge centrifuge with a differential speed of 10rpm. S5. Product Upgrading: The concentrates obtained from S2.3, S3, and S4 are combined and finalized using a heavy media separator. The heavy media is a magnetically stable heavy liquid, which is a solid-liquid suspension system composed of ultrafine magnetite powder and an organic carrier. The magnetite powder has a particle size ≤5μm and the suspension stability is maintained by mechanical stirring. The organic carrier is a bio-based zwitterionic polymer solution, consisting of the following components: 2.25wt% biodegradable anionic polysaccharide derivative; 0.5wt% quaternized plant gum cationic modifier; and the balance being water. S6. Concentrate dewatering: The concentrate obtained in step S5 is dewatered through two-stage vacuum filtration to obtain dewatered lead-zinc concentrate with a moisture content of ≤15%. In the two-stage vacuum filtration, the vacuum degree of the first stage filtration is -0.07MPa and the vacuum degree of the second stage filtration is -0.09MPa. S7. Filter water circulation: The filter water produced by dehydration is fed into the inclined plate sedimentation tank. After the filter water stays in the sedimentation tank for 45 minutes, the supernatant is returned to step S2.1 as rinsing water for reuse.

[0035] Example 2 See attached document Figure 1 A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment includes the following steps: S1. Raw material pretreatment: The lead-zinc tailings are crushed to a particle size of ≤5mm and then passed through a three-stage vibrating screen with a vibration frequency of 1800rpm and screen mesh sizes of 20, 80 and 200 meshes, respectively, to separate the target particle group with a particle size of 0.075mm to 2mm. The material on the screen is returned to the crushing process. S2, Multi-stage reselection enrichment: S2.1. A composite spiral sluice is used to rough the target particle group. The trapezoidal groove of the composite spiral sluice has a depth of 0.5 mm, a groove spacing of 3 mm, a sluice inclination angle of 14°, and a washing water pressure of 0.8 MPa to finally obtain a rough concentrate. S2.2. Input the rough concentrate into a centrifuge with backwash water regulation function for primary cleaning. The centrifugal force intensity is 200G and the backwash water flow rate is 40L / min. The backwash water flow rate is dynamically adjusted according to the slurry density in the centrifuge. S2.3 The primary selected product enters a vibrating shaker for secondary selection, wherein the slope of the coarse selection zone is 2.5°, the slope of the selection zone is 0.5°, the amplitude is 8mm, and the stroke rate is 250 times / minute. S3. Magnetoelectric Co-processing for Impurity Removal: The product from the secondary selection is crushed to 0.1mm, then classified by a hydrocyclone, and the underflow enters a high-intensity magnetic separator for impurity removal under a background field strength of 1.2T superimposed with a pulsed magnetic field. The high-intensity magnetic separator adopts a vertical ring magnetic system with a peak pulsed magnetic field strength of 1.8T. S4. Fine particle recovery: The centrifugal tailings from step S2.2 are directly fed into the cyclone-centrifugal coupling device containing an acoustic wave transmitter. The magnetic separation tailings from step S3 are fed into the device after being regrinded to 0.043mm. The cyclone cone angle is 15° and the ultrasonic frequency is 28kHz. The centrifugal unit of the cyclone-centrifugal coupling device is a horizontal screw discharge centrifuge with a differential speed of 8rpm. S5. Product Upgrading: The concentrates obtained from S2.3, S3, and S4 are combined and finalized using a heavy media separator. The heavy media is a magnetically stable heavy liquid, which is a solid-liquid suspension system composed of ultrafine magnetite powder and an organic carrier. The magnetite powder has a particle size ≤5μm and the suspension stability is maintained by mechanical stirring. The organic carrier is a bio-based zwitterionic polymer solution, consisting of the following components: 1.5wt% biodegradable anionic polysaccharide derivative; 0.2wt% quaternized plant gum cationic modifier; and the balance being water. S6. Concentrate dewatering: The concentrate obtained in step S5 is dewatered by two-stage vacuum filtration to obtain dewatered lead-zinc concentrate with a moisture content of ≤15%. In the two-stage vacuum filtration, the vacuum degree of the first stage filtration is -0.06MPa and the vacuum degree of the second stage filtration is -0.08MPa. S7. Filter water circulation: The filter water produced by dehydration is fed into the inclined plate sedimentation tank. After the filter water stays in the sedimentation tank for 30 minutes, the supernatant is returned to step S2.1 as rinsing water for reuse.

[0036] Example 3 See attached document Figure 1 A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment includes the following steps: S1. Raw material pretreatment: The lead-zinc tailings are crushed to a particle size of ≤5mm and then passed through a three-stage vibrating screen with a vibration frequency of 2400rpm and screen mesh sizes of 20, 80 and 200 meshes, respectively, to separate the target particle group with a particle size of 0.075mm to 2mm. The material on the screen is returned to the crushing process. S2, Multi-stage reselection enrichment: S2.1. A composite spiral sluice is used to rough the target particle group. The trapezoidal groove of the composite spiral sluice has a depth of 1.0 mm, a groove spacing of 5 mm, a sluice inclination angle of 18°, and a washing water pressure of 1.2 MPa to finally obtain a rough concentrate. S2.2. Input the rough concentrate into a centrifuge with backwash water regulation function for primary cleaning. The centrifugal force intensity is 350G and the backwash water flow rate is 50L / min. The backwash water flow rate is dynamically adjusted according to the slurry density in the centrifuge. S2.3 The primary selected product enters a vibrating shaker for secondary selection, wherein the slope of the coarse selection zone is 3.5°, the slope of the selection zone is 1.5°, the amplitude is 120mm, and the stroke rate is 350 times / minute. S3. Magnetoelectric Co-processing for Impurity Removal: The product from the secondary selection is crushed to 0.3mm, then classified by a hydrocyclone, and the underflow enters a high-intensity magnetic separator for impurity removal under a background field strength of 1.2T superimposed with a pulsed magnetic field. The high-intensity magnetic separator adopts a vertical ring magnetic system with a peak pulsed magnetic field strength of 1.8T. S4. Fine particle recovery: The centrifugal tailings from step S2.2 are directly fed into the cyclone-centrifugal coupling device containing an acoustic transmitter. The magnetic separation tailings from step S3 are fed into the device after being regrinded to 0.074mm. The cyclone cone angle is 20° and the ultrasonic frequency is 40kHz. The centrifugal unit of the cyclone-centrifugal coupling device is a horizontal screw discharge centrifuge with a differential speed of 12rpm. S5. Product Upgrading: The concentrates obtained from S2.3, S3, and S4 are combined and finalized using a heavy media separator. The heavy media is a magnetically stable heavy liquid, which is a solid-liquid suspension system composed of ultrafine magnetite powder and an organic carrier. The magnetite powder has a particle size ≤5μm and the suspension stability is maintained by mechanical stirring. The organic carrier is a bio-based zwitterionic polymer solution, consisting of the following components: 3.0wt% biodegradable anionic polysaccharide derivative; 0.8wt% quaternized plant gum cationic modifier; and the balance being water. S6. Concentrate dewatering: The concentrate obtained in step S5 is dewatered by two-stage vacuum filtration to obtain dewatered lead-zinc concentrate with a moisture content of ≤15%. In the two-stage vacuum filtration, the vacuum degree of the first stage filtration is -0.08MPa and the vacuum degree of the second stage filtration is -0.10MPa. S7. Filter water circulation: The filter water produced by dehydration is input into the inclined plate sedimentation tank. After the filter water stays in the sedimentation tank for 60 minutes, the supernatant is returned to step S2.1 as rinsing water for reuse.

[0037] Comparative Example 1 A method for extracting high-grade fine lead-zinc ore from lead-zinc tailings using gravity separation equipment differs from Example 1 only in that the partitioning design of the roughing zone (3.0°) and the cleaning zone (1.0°) is eliminated. Specifically, the vibrating shaker in step S2.3 is set to a uniform slope of 2.0°, and the steps are exactly the same as in Example 1.

[0038] Comparative Example 2 A method for extracting high-grade lead-zinc ore from lead-zinc tailings using gravity separation equipment differs from Example 1 only in that the separate path design of direct treatment of centrifugal tailings and regrinding of magnetic tailings is eliminated. Specifically, in step S4, the centrifugal tailings and magnetic tailings are mixed and directly fed into the cyclone-centrifugal coupling device, and the steps are exactly the same as in Example 1.

[0039] Comparative Example 3 A method for extracting high-grade fine lead-zinc ore from lead-zinc tailings using gravity separation equipment differs from Example 1 only in that: the heavy liquid carrier in step S5 is replaced with a kerosene-magnetite powder suspension system, wherein the kerosene accounts for 40 wt% and the magnetite powder has a D50 of 2-5 μm. Stability is maintained by mechanical stirring, and the bio-based zwitterionic polymer is omitted. The steps are exactly the same as in Example 1.

[0040] Comparative Example 4 A method for extracting high-grade fine lead-zinc ore from lead-zinc tailings using gravity separation equipment differs from Example 1 only in that the pulsed magnetic field superposition is eliminated. Specifically, in step S3, the strong magnetic separator uses a steady-state background field strength of 1.0T, and the peak intensity parameter of the pulsed magnetic field is deleted. The steps are exactly the same as in Example 1.

[0041] Comparative Example 5 A method for extracting high-grade fine lead-zinc ore from lead-zinc tailings using gravity separation equipment differs from Example 1 only in that: in step S5, the method for maintaining the stability of the heavy liquid is changed to electromagnetic field stabilization with a magnetic field strength of 0.3T, and mechanical stirring is eliminated. The steps are exactly the same as in Example 1.

[0042] Comparative Example 6 A method for extracting high-grade fine lead-zinc ore from lead-zinc tailings using gravity separation equipment differs from Example 1 only in that: in step S7, 0.1 wt% polyacrylamide flocculant is added to the inclined plate sedimentation tank, and the residence time is shortened to 20 minutes, while the other parameters remain unchanged, and the steps are exactly the same as in Example 1.

[0043] The results of the key performance tests of Examples 1-3 and Comparative Examples 1-6 are shown in Table 1.

[0044] Table 1:

[0045] 1. The test standard for lead / zinc recovery rate is: GB / T25952-2010 "Calculation Method of Technical Indicators for Lead-Zinc Ore Beneficiation"; 2. The testing standard for Pb / Zn grade of zinc concentrate is GB / T8151.1-2012 "Chemical Analysis Methods for Zinc Concentrate"; 3. The test standard for the capture rate of 10-38μm particles is: YS / T438.1-2014 "Particle Size Analysis and Sieving Method of Non-ferrous Metal Ores"; 4. The test standard for biotoxicity (luminescent bacteria method) is: GB / T15441-1995 "Determination of acute toxicity of water by luminescent bacteria method"; 5. The test standard for total energy consumption is GB21252-2013 "Energy Consumption Limits for Non-ferrous Metal Mine Beneficiation".

[0046] As can be seen from Examples 1-3 and Comparative Example 1 and Table 1, by designing the slope difference between the coarse and fine selection zones of the vibrating shaker, the slurry flow rate gradient can be controlled, thereby promoting the zoning and enrichment of coarse and fine particles on the bed surface. However, the lack of slope zoning leads to insufficient interlayer shear force of mineral particles, which will reduce the migration efficiency of heavy minerals and cause disorder in the interlayer zoning of mineral particles.

[0047] Based on Examples 1-3 and Comparative Example 2, and in conjunction with Table 1, it can be seen that by directly processing centrifugal tailings and inputting them via separate paths after regrinding magnetic separation tailings, the separation characteristics of materials with different particle sizes can be specifically matched: centrifugal tailings contain primary fine particles, and direct processing avoids over-grinding; regrinding magnetic separation tailings to 0.043-0.074mm releases inclusions, while mixed processing will cause coarse and fine particles to interfere with each other, thereby weakening the accuracy of cyclone field separation.

[0048] Based on Examples 1-3 and Comparative Example 3, and in conjunction with Table 1, it can be seen that the bio-based zwitterionic polymer solution can stabilize the magnetite powder suspension system through intermolecular electrostatic forces and steric hindrance effects; while the kerosene carrier, due to its non-polar characteristics, leads to an imbalance in the wettability of the mineral surface, thereby increasing the risk of media agglomeration.

[0049] As can be seen from Examples 1-3 and Comparative Example 4, and Table 1, alternating magnetic field lines are generated by superimposing a pulsed magnetic field on the background field strength, which can then apply a high-frequency oscillating force to weakly magnetic impurities, thereby promoting the dissociation of the intergrowth interface. In contrast, the steady-state magnetic field only achieves static adsorption and thus cannot destroy the micro-particle encapsulation structure.

[0050] As can be seen from Examples 1-3 and Comparative Example 5 and Table 1, the stability of the heavy liquid suspension is maintained by mechanical stirring because the particles are dispersed by fluid shear force; while the electromagnetic field requires continuous electrical energy to maintain a magnetic field of 0.3T, and the electromagnetic eddy current may interfere with the mineral settling trajectory and cause the dissipation of eddy current inside the heavy medium, thereby increasing energy consumption.

[0051] As can be seen from Examples 1-3 and Comparative Example 6, and Table 1, solid-liquid separation is achieved by letting the filtered water stay in the inclined plate sedimentation tank for 30-60 minutes, relying on gravity sedimentation. Although adding flocculants shortens the residence time, residual organic molecules are adsorbed on the mineral surface, thereby changing the chemical environment of the subsequent gravity separation system solution.

[0052] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment, characterized in that: Includes the following steps: S1. Raw material pretreatment: The lead-zinc tailings are crushed to a particle size of ≤5mm, and the target particle group with a particle size of 0.075mm to 2mm is separated by screening. The material on the screen is returned to the crushing process. S2, Multi-stage reselection enrichment: S2.

1. A composite spiral sluice is used to rough the target particle group. The sluice inclination angle is controlled between 14° and 18°, and the flushing water pressure is controlled between 0.8 and 1.2 MPa to obtain a rough concentrate. S2.

2. Input the rough concentrate into a centrifuge with backwash water regulation function for primary cleaning, with a centrifugal force intensity of 200 to 350G and a backwash water flow rate of 30 to 50L / min; S2.3 The primary selected product enters a vibrating shaker for secondary selection, wherein the slope of the coarse selection zone is 2.5° to 3.5°, the slope of the selection zone is 0.5° to 1.5°, the amplitude is 8 to 12 mm, and the stroke rate is 250 to 350 times / minute. S3. Magnetoelectric Co-processing Impurity Removal: The product from the secondary selection is crushed to 0.1-0.3mm, then classified by a hydrocyclone, and the underflow enters a high-intensity magnetic separator for impurity removal under a background field strength of 0.8-1.2T superimposed pulsed magnetic field. S4. Fine particle recovery: The centrifugal tailings from step S2.2 are directly fed into a cyclone-centrifugal coupling device containing an acoustic wave transmitter. The magnetic separation tailings from step S3 are fed in after being regrinded to 0.043-0.074mm. The cone angle of the cyclone is 15° to 20° and the ultrasonic frequency is 28 to 40kHz. S5. Product quality improvement: The concentrates obtained from S2.3, S3 and S4 are combined and the final separation is carried out using a heavy medium separator. The heavy medium is a magnetically stable heavy liquid. S6. Concentrate dewatering: The concentrate obtained in step S5 is dewatered by two-stage vacuum filtration to obtain dewatered lead-zinc concentrate with a moisture content of ≤15%. S7. Filter water circulation: Input the filtered water produced by dehydration into the inclined plate sedimentation tank.

2. The method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S1, the screening and separation adopts a three-layer stepped vibrating screen with screen mesh numbers of 20 mesh, 80 mesh and 200 mesh, and vibration frequency of 1800 to 2400 rpm.

3. The method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S2.1, the trapezoidal groove of the composite spiral chute has a depth of 0.5 to 1.0 mm and a groove spacing of 3 to 5 mm.

4. The method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S2.2, the backwash water flow rate is dynamically adjusted according to the slurry density inside the centrifuge.

5. The method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S3, the strong magnetic separator adopts a vertical ring magnetic system with a pulse magnetic field peak intensity of 1.2-1.8T.

6. The method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S5, the heavy liquid is a solid-liquid suspension system composed of ultrafine magnetite powder and an organic carrier, wherein the magnetite powder has a particle size ≤5μm and the suspension stability is maintained by mechanical stirring.

7. A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 6, characterized in that: The organic carrier is a bio-based zwitterionic polymer solution, consisting of the following components: 1.5-3.0 wt% biodegradable anionic polysaccharide derivative; 0.2-0.8 wt% quaternized plant gum cationic modifier; and the balance being water.

8. The method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S7, after the filtered water stays in the sedimentation tank for 30 to 60 minutes, the supernatant is returned to step S2.1 as rinsing water for reuse.

9. A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S4, the centrifugal unit of the cyclone-centrifugal coupling device is a horizontal screw discharge centrifuge with a differential speed of 8-12 rpm.

10. A method for extracting high-grade refined lead-zinc ore from lead-zinc tailings using gravity separation equipment according to claim 1, characterized in that: In step S6, during the two-stage vacuum filtration dewatering, the vacuum degree of the first-stage filtration is -0.06 to -0.08 MPa, and the vacuum degree of the second-stage filtration is -0.08 to -0.1 MPa.

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