Tin recovery method for secondary tailings

Abstract

The invention provides a tin recovery method for secondary tailings. The tin recovery method comprises the following steps: (1) feeding; (2) physical reselection; (3) thickening; (4) the flotation process comprises the following steps: S1, feeding; s2, pulp mixing is conducted, butyl xanthate and second oil are added into the ore pulp, sulphide ore is removed through flotation, and the sulphide ore and desulfurized tailings are obtained; the method comprises the following steps: concentrating and mixing iron-removed tailings to 22-25%, adding sodium carbonate, and stirring for 5-8 minutes; adding sodium hexametaphosphate, and stirring for 3-5 minutes; adding tributyl phosphate, and stirring for 12-16 minutes; adding a hydroximic acid collecting agent, and stirring for 3-5 minutes; then 30-50 g / t of second oil is added, stirring is conducted for 1-2 minutes, and roughing concentrate and roughing tailings are obtained; s3, air inflation is carried out; s4, separating; and (5) upgrading the secondary concentrate to obtain the tin concentrate. According to the beneficiation method, the tin concentrate product is high in tin-containing grade and high in recovery rate.

Description

Technical Field

[0001] The invention belongs to the technical field of ore dressing, and in particular relates to a method for recovering tin from secondary tailings. Background Art

[0002] Secondary tailings refer to the mineral resources that have not been effectively recovered in the primary beneficiation process, and the waste residues remaining after further processing. Due to the limited recovery rate in the primary beneficiation process, secondary tailings may still contain a certain amount of valuable metals, such as tin. With the increasing scarcity of resources and the improvement of environmental protection requirements, the recovery of valuable metals in secondary tailings has become increasingly important.

[0003] The tin content in secondary tailings is usually low, generally between 0.1% and 1%, depending on the process and efficiency of the primary beneficiation. Although the content is not high, the overall tin resource still has considerable economic value due to the large amount of tailings. In addition, with the gradual reduction of tin resources, the recovery of low-grade tin ores has become increasingly important. Flotation is a method of separation using the difference in the surface properties of minerals. By adding collectors, frothers and other reagents, cassiterite particles are attached to bubbles and rise to the surface of the slurry with the bubbles to form a foam layer, thereby separating them from the gangue minerals. Flotation is suitable for processing fine-grained and micro-fine-grained cassiterite, which can effectively improve the recovery rate of tin. Especially for tailings with a high mud content, flotation can remove muddy minerals and improve the grade of the concentrate. Magnetic separation is a separation method based on the difference in the magnetic properties of minerals. Although cassiterite itself is not magnetic, it can be pre-oxidized or reduced to generate weakly magnetic compounds on the surface of cassiterite, so that it can be separated by magnetic separation equipment. Magnetic separation is suitable for processing tailings containing magnetic minerals such as iron and titanium, and can recover multiple valuable metals at the same time. For certain types of tailings, magnetic separation can be used as an effective pre-enrichment method.

[0004] The tin content in secondary tailings is usually low, and how to achieve efficient tin recovery in low-grade ores is an important challenge. Traditional beneficiation methods have a low recovery rate for low-grade ores and are difficult to meet economic requirements. By introducing green beneficiation technology and environmentally friendly reagents, the impact on the environment can be reduced. For example, bioleaching is a green and environmentally friendly technology that can be carried out at normal temperature and pressure, with low energy consumption and little environmental pollution. In addition, the use of a closed-loop circulation system can effectively reduce the discharge of wastewater and exhaust gas.

[0005] Therefore, a tin recovery method for secondary tailings is urgently needed. Summary of the invention

[0006] The purpose of the present invention is to provide a method for recovering tin from secondary tailings.

[0007] In order to achieve the above object, the present invention provides the following technical solutions: A method for recovering tin from secondary tailings comprises the following steps: (1) Feeding: For the secondary tin tailings of fine-grained tin ore, they are first concentrated through a high-efficiency inclined plate thickener, with the concentration controlled at 14%~18%. After the concentration is increased, they are fully stirred and then enter the physical concentrator through a pressure stabilizing box; (2) Physical gravity separation: The centrifugal drum of the physical concentrator rotates horizontally, generating a centrifugal force field with uniform radial distribution on the inner surface of the drum. The slurry is fed to the inner surface of the drum by the feeding device and rotates along with the drum under the drive of the centrifugal drum. There is a slope along the axial direction of the inner surface of the centrifugal drum. The slurry flow rotates and flows along the axial direction at a certain flow rate. (3) Thickening: The physical concentrator will discharge the high-density products into the separation device and discharge them into the concentrate receiving tank, and then enter the high-efficiency inclined plate thickener for concentration. The discharge port of the thickener is designed with a timed air pump mechanism to perform air intake and stirring. The concentration is controlled at 35%~45% and enters the flotation for quality improvement.

[0008] (4) Flotation process: The basic steps of flotation process include: S1. Feeding: The products with high specific gravity from the physical concentrator are discharged into the ore separation device and then into the concentrate receiving tank. They are then concentrated in the high-efficiency inclined plate thickener. The discharge port of the thickener is designed with a timed air pump mechanism for air intake and stirring. The concentration is controlled at 35%~45% before entering the flotation for quality improvement. S2, slurry adjustment: add 150-170g / t of butyl xanthate and 24-28g / t of No. 2 oil to the slurry, flotation remove sulfide ore to obtain sulfide ore and desulfurized tailings; magnetic separation of desulfurized tailings removes iron at a magnetic field strength of 0.2-0.3T to obtain iron concentrate and deironized tailings; concentrate and slurry the deironized tailings to 22-25%, add 250-280g / t of sodium carbonate, and stir for 5-8 minutes; add 120-150g / t of sodium hexametaphosphate, stir for 3-5 minutes; add 90-100g / t of tributyl phosphate, stir for 12-16 minutes; then add 700-800g / t of hydroxamic acid collector, stir for 3-5 minutes; then add 30-50g / t of No. 2 oil, stir for 1-2 minutes, and obtain rougher concentrate and rougher tailings; S3. Aeration: Introduce air into the rougher concentrate to form a large number of bubbles.

[0009] S4. Separation: Hydrophobic mineral particles adhere to the bubbles and float up to form a mineralized foam layer, while hydrophilic mineral particles remain in the slurry and discharge the mineralized foam to achieve the purpose of separation; (5) Secondary concentrate upgrading: The flotation concentrate enters the physical concentrator for secondary upgrading to obtain tin concentrate. The tailings are fully recovered and circulated into the high-efficiency inclined plate thickener for concentration. The concentration is adjusted to 35%~45% and then returned to the flotation machine for repeated screening.

[0010] In the secondary tin recovery process, a series of fine flotation, magnetic separation and reagent addition operations can significantly improve the tin grade in the concentrate and the operating tin recovery rate. In the method of the present invention, when flotation removes sulfide ores, butyl xanthate is a commonly used sulfide ore collector, which can selectively adsorb on the surface of sulfide ores (such as pyrite, molybdenite, etc.), making them hydrophobic, so that they float up with bubbles during flotation and separate from gangue minerals. Dosage: The dosage of butyl xanthate of 150-170g / t is moderate, which can effectively capture sulfide ores without affecting tin minerals, avoiding the interference of sulfide ores with subsequent tin recovery. By removing sulfide ores by flotation, the content of sulfide ores in tailings is reduced, and the encapsulation and interference of sulfide ores on tin minerals are reduced, which helps to improve the subsequent separation efficiency of tin minerals, thereby improving the tin grade in the concentrate. No. 2 oil is a foaming agent that can produce a stable foam layer, helping the sulfide ore particles adsorbed by the collector to adhere to the bubbles, rise to the surface of the slurry with the bubbles, and form a foam layer for discharge; Dosage: 24-28g / t of No. 2 oil is moderate, which can provide sufficient foam stability to ensure the effective flotation of sulfide ore, while not excessively foaming, which affects the stability and efficiency of the flotation process. By using an appropriate amount of No. 2 oil, the efficient flotation of sulfide ore is ensured, the removal rate of sulfide ore is further improved, and favorable conditions are created for the subsequent separation of tin minerals.

[0011] When removing iron by magnetic separation, magnetic separation is carried out at a magnetic field strength of 0.2-0.3T, which can effectively separate iron minerals (such as magnetite, hematite, etc.) from tailings. Iron minerals have strong magnetism and will be adsorbed on the drum of the magnetic separator under the action of the magnetic field, while tin minerals and other non-magnetic minerals remain in the tailings. By removing iron by magnetic separation, the content of iron minerals in the tailings is reduced, and the wrapping and interference of iron minerals on tin minerals is avoided, which helps to improve the subsequent separation efficiency of tin minerals and thus improve the tin grade in the concentrate. Concentrating the iron-removed tailings to a solid-liquid ratio of 22-25% can reduce the moisture content in the pulp, increase the concentration of the pulp, and facilitate the subsequent flotation process. A higher pulp concentration can improve the processing capacity of the flotation machine, reduce the loss of pulp, and thus improve the recovery rate of tin. Concentrated pulping can improve the processing efficiency of the flotation machine, reduce the loss of pulp, ensure that more tin minerals enter the flotation process, and thus improve the recovery rate of tin.

[0012] Sodium carbonate is an alkaline adjuster that can adjust the pH value of the pulp. It is usually used to adjust the pH value of the pulp to a weak alkaline (pH 8-9). Under weak alkaline conditions, the hydrophilicity of the surface of the tin mineral is reduced, which is conducive to the adsorption of the collector, thereby improving the flotation performance of the tin mineral. The moderate dosage of 250-280g / t of sodium carbonate can effectively adjust the pH value of the pulp and ensure that the surface properties of the tin mineral are suitable for flotation. By adjusting the pH value of the pulp, the hydrophobicity of the tin mineral is enhanced, the combination of the tin mineral and the collector is promoted, the flotation efficiency of the tin mineral is improved, and the tin grade in the concentrate is increased.

[0013] Sodium hexametaphosphate is a dispersant that can inhibit the flotation of gangue minerals (such as quartz, feldspar, etc.) and prevent them from entering the concentrate together with tin minerals. In addition, sodium hexametaphosphate can dissolve impurities on the surface of minerals and improve the flotation environment of tin minerals. Dosage: 120-150g / t of sodium hexametaphosphate is moderately used, which can effectively inhibit the flotation of gangue minerals and reduce the encapsulation and interference of gangue minerals on tin minerals. By inhibiting the flotation of gangue minerals, the gangue content in the concentrate is reduced, the purity of the concentrate is improved, and then the tin grade in the concentrate is improved.

[0014] Tributyl phosphate is an activator that can activate the surface of tin minerals and enhance the binding ability of tin minerals with collectors. TBP can react with oxides or hydroxides on the surface of tin minerals to form hydrophobic complexes, which promote the flotation of tin minerals. Dosage: 90-100g / t of tributyl phosphate is moderate, which can effectively activate tin minerals and enhance their flotation performance. By activating the surface of tin minerals, the binding ability of tin minerals with collectors is enhanced, the flotation efficiency of tin minerals is improved, and the tin quality in the concentrate is increased.

[0015] Hydroxamic acid collectors (such as ethyl hydroxamic acid) are highly efficient tin mineral collectors that can selectively adsorb on the surface of tin minerals, making them hydrophobic, so that they float up with bubbles during flotation and are separated from gangue minerals. Dosage: 700-800g / t of hydroxamic acid collectors are used in large quantities, but this is to ensure the full capture of tin minerals, especially in the case of fine-grained and micro-fine-grained tin minerals, where a larger amount can improve the capture effect. By using hydroxamic acid collectors, efficient flotation of tin minerals is ensured, especially for fine-grained and micro-fine-grained tin minerals, the capture effect is significant, and the recovery rate of tin is improved.

[0016] The purpose of adding No. 2 oil again is to provide sufficient foam stability to ensure that the tin minerals can float with the bubbles to form a stable foam layer, which is convenient for the subsequent collection of concentrate. Dosage: 30-50g / t of No. 2 oil is moderate, which can provide sufficient foam stability to ensure the effective flotation of tin minerals, while not causing excessive foaming, which affects the stability and efficiency of the flotation process. By using an appropriate amount of No. 2 oil, the efficient flotation of tin minerals is ensured, and the recovery rate of tin is further improved.

[0017] Furthermore, the feed characteristics of the physical concentrator are a processing capacity of 1.3~1.8T dry ore / hour, a feed concentration of 14%~18%, and an initial feed velocity of 0.8~1m / s.

[0018] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: in the method of the present invention, sulfide ore and ferromagnetic minerals can be removed respectively by flotation removal of sulfide ore and magnetic separation to remove iron, thereby effectively reducing the interference of sulfide ore and ferromagnetic minerals on subsequent flotation cassiterite, and at the same time, the selected grade of the flotation operation can be further improved.

[0019] The method of the present invention can significantly improve the tin grade in the concentrate and the operating tin recovery rate through a series of operations, especially flotation removal of sulfide ore, magnetic separation of iron, adjustment of pulp pH value, inhibition of gangue minerals, activation of tin minerals and use of efficient collectors. By flotation removal of sulfide ore and magnetic separation of iron, the interference of gangue minerals and iron minerals is reduced, and the efficient separation of tin minerals is ensured; by adjusting the pulp pH value, inhibiting gangue minerals, and activating tin minerals, the flotation performance of tin minerals is further improved, the mixing of gangue minerals is reduced, and thus the tin grade in the concentrate is improved. By using efficient collectors and appropriate frothers, the full capture of tin minerals is ensured, especially the capture effect of fine-grained and micro-fine-grained tin minerals is significant, and the recovery rate of tin is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The process flow chart of the tin recovery method of secondary tailings of the present invention is as follows; Figure 2 It is a top view schematic diagram of a physical ore dressing machine; Figure 3 It is a schematic side view of a physical concentrator; Figure 4 This is a front view schematic diagram of a physical ore dressing machine. DETAILED DESCRIPTION

[0021] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Example 1 This embodiment provides a method for recovering tin from secondary tailings, comprising the following steps: (1) Feeding: For the secondary tin tailings of fine-grained tin ore, they are first concentrated by a high-efficiency inclined plate thickener, with the concentration controlled at 15%. After the concentration is increased, they are fully stirred and then enter the physical concentrator through a pressure stabilizing box; (2) Physical gravity separation: The centrifugal drum of the physical ore concentrator rotates horizontally, generating a radially uniformly distributed centrifugal force field on the inner surface of the drum. The slurry is fed to the inner surface of the drum by the feeding device and rotates along with the drum under the drive of the centrifugal drum. There is a slope along the axial direction of the inner surface of the centrifugal drum. While the slurry flow rotates, it also flows along the axial direction at a certain flow rate. The slurry moves in a spiral shape along the axial direction on the inner surface of the drum. Under the combined action of the weak turbulent flow film and the centrifugal force field, the spiral slurry flow selectively separates the ore particles of different densities. The high-density ore particles are centrifugally settled onto the inner surface of the centrifugal drum in a very short time, and rotate with the drum in the form of a compacted thin layer of particles; the low-density ore particles are unable to reach the bottom layer of the flow film due to the pulsation diffusion of the flow film, and are discharged along the slope of the drum along with the liquid phase to become low-density products (tailings, fine mud, impurities), which are discharged into the tailings receiving trough through the ore separation device; when the ore feeding is suspended, the ore flushing device will flush the high-density products (concentrates, high-density metals) into the ore separation device and discharge them into the concentrate receiving trough.

[0023] Physical concentrators (centrifuges) are based on the principle of flow film separation in a centrifugal field. In order to ensure a good centrifugal separation effect, the stability of the feed (processing capacity 1.5T (dry ore) / hour, feed concentration 15%, and feed initial velocity 0.9m / s) is crucial. Therefore, the feed must first enter the pressure stabilizing (separation) box and then be fed to the centrifugal concentrator. In addition, the rinsing water and flushing water of the centrifugal concentrator are filtered to remove +0.5mm impurities in the water. The rinsing water pressure is required to reach 0.1Mpa, and the flushing water pressure is required to reach 0.6Mpa.

[0024] (3) Thickening: The physical concentrator discharges the high-density products (concentrates, high-density metals) into the separation device and discharges them into the concentrate receiving tank. The products then enter the high-efficiency inclined plate thickener for thickening. The thickener discharge port is designed with a timed air pump mechanism to perform air intake and stirring (20S / time / 3S) to ensure the stability of the discharge concentration at the discharge port. The concentration is controlled at 40% before entering the flotation for quality improvement.

[0025] (4) Principle of flotation process: It is a method of mineral separation based on the difference in physical and chemical properties of the mineral surface. The core of the flotation process is to utilize the difference in hydrophobicity and hydrophilicity of the mineral surface. By introducing bubbles into the slurry, the hydrophobic mineral particles are attached to the bubbles and then float up, thereby achieving the purpose of separation. The flotation process is widely used in the separation of non-ferrous metals (such as copper, zinc, lead, nickel, gold, tin, tungsten, etc.) and non-metallic minerals, and is particularly suitable for processing fine and micro-fine materials. Its advantages include a wide range of applications, strong adaptability, and the ability to process a variety of ores.

[0026] The basic steps of flotation process include: S1. Feeding: The products with high specific gravity (concentrates, high specific gravity metals) from the physical concentrator (centrifuge) are discharged to the separation device and discharged into the concentrate receiving tank, and then enter the high-efficiency inclined plate thickener for concentration. The discharge port of the thickener is designed with a timed air pump mechanism to perform air intake and stirring (20S / time / 3S) to ensure the stability of the discharge concentration at the discharge port. The concentration is controlled at 40% to enter flotation for quality improvement. The ore is made to meet the particle size required by flotation, so that the useful minerals are basically dissociated into monomers for sorting. The less mud, iron and sulfur content, the easier it is to sort.

[0027] S2, slurry preparation: add 150g / t of butyl xanthate and 24g / t of No. 2 oil to the slurry, flotation remove sulfide ore to obtain sulfide ore and desulfurized tailings; magnetic separation of desulfurized tailings removes iron at a magnetic field strength of 0.2T to obtain iron concentrate and deironized tailings; concentrate the deironized tailings to 22%, add 250g / t of sodium carbonate, and stir for 5 minutes; add 120g / t of sodium hexametaphosphate, stir for 3 minutes; add 90g / t of tributyl phosphate, stir for 12 minutes; then add 700g / t of hydroxamic acid collector, stir for 3 minutes; then add 30g / t of No. 2 oil, stir for 1 minute, and obtain rougher concentrate and rougher tailings; S3. Aeration: Introduce air into the rougher concentrate to form a large number of bubbles.

[0028] S4. Separation: Hydrophobic mineral particles attach to the bubbles and float up to form a mineralized foam layer, while hydrophilic mineral particles remain in the slurry and discharge the mineralized foam to achieve the purpose of sorting.

[0029] (5) Secondary concentrate quality improvement: The flotation concentrate enters the physical concentrator (centrifuge) for secondary quality improvement, which can greatly improve the concentrate grade. The higher the feed grade, the higher the enrichment ratio. The tailings are fully recovered and circulated into the high-efficiency inclined plate thickener for concentration. The concentration is adjusted to 40% and then returned to the flotation machine for repeated screening to maximize the comprehensive recovery rate and realize the recovery and recycling of resources. Finally, the tin concentrate is dehydrated by concentrated filter press.

[0030] Example 2 This embodiment provides a method for recovering tin from secondary tailings, comprising the following steps: (1) Feeding: For the secondary tin tailings of fine-grained tin ore, they are first concentrated by a high-efficiency inclined plate thickener, with the concentration controlled at 18%. After the concentration is increased, they are fully stirred and then enter the physical concentrator through a pressure stabilizing box; (2) Physical gravity separation: The centrifugal drum of the physical ore concentrator rotates horizontally, generating a radially uniformly distributed centrifugal force field on the inner surface of the drum. The slurry is fed to the inner surface of the drum by the feeding device and rotates along with the drum under the drive of the centrifugal drum. There is a slope along the axial direction of the inner surface of the centrifugal drum. While the slurry flow rotates, it also flows along the axial direction at a certain flow rate. The slurry moves in a spiral shape along the axial direction on the inner surface of the drum. Under the combined action of the weak turbulent flow film and the centrifugal force field, the spiral slurry flow selectively separates the ore particles of different densities. The high-density ore particles are centrifugally settled onto the inner surface of the centrifugal drum in a very short time, and rotate with the drum in the form of a compacted thin layer of particles; the low-density ore particles are unable to reach the bottom layer of the flow film due to the pulsation diffusion of the flow film, and are discharged along the slope of the drum along with the liquid phase to become low-density products (tailings, fine mud, impurities), which are discharged into the tailings receiving trough through the ore separation device; when the ore feeding is suspended, the ore flushing device will flush the high-density products (concentrates, high-density metals) into the ore separation device and discharge them into the concentrate receiving trough.

[0031] Physical concentrators (centrifuges) are based on the principle of flow film separation in a centrifugal field. In order to ensure a good centrifugal separation effect, the stability of the feed (processing capacity 1.8T (dry ore) / hour, feed concentration 14%, and feed initial velocity 1m / s) is crucial. Therefore, the feed must first enter the pressure stabilizing (separation) box and then be fed to the centrifugal concentrator. In addition, the rinsing water and flushing water of the centrifugal concentrator are filtered to remove +0.5mm impurities in the water. The rinsing water pressure is required to reach 0.1Mpa, and the flushing water pressure is required to reach 0.6Mpa.

[0032] (3) Thickening: The physical concentrator discharges the high-density products (concentrates, high-density metals) into the separation device and discharges them into the concentrate receiving tank. The products then enter the high-efficiency inclined plate thickener for thickening. The thickener discharge port is designed with a timed air pump mechanism to perform air intake and stirring (20S / time / 3S) to ensure the stability of the discharge concentration at the discharge port. The concentration is controlled at 45% before entering the flotation for quality improvement.

[0033] (4) Principle of flotation process: It is a method of mineral separation based on the difference in physical and chemical properties of the mineral surface. The core of the flotation process is to utilize the difference in hydrophobicity and hydrophilicity of the mineral surface. By introducing bubbles into the slurry, the hydrophobic mineral particles are attached to the bubbles and then float up, thereby achieving the purpose of separation. The flotation process is widely used in the separation of non-ferrous metals (such as copper, zinc, lead, nickel, gold, tin, tungsten, etc.) and non-metallic minerals, and is particularly suitable for processing fine and micro-fine materials. Its advantages include a wide range of applications, strong adaptability, and the ability to process a variety of ores.

[0034] The basic steps of flotation process include: S1. Feeding: The products with high specific gravity (concentrates, high specific gravity metals) from the physical concentrator (centrifuge) are discharged to the separation device and discharged into the concentrate receiving tank, and then enter the high-efficiency inclined plate thickener for concentration. The discharge port of the thickener is designed with a timed air pump mechanism to perform air intake and stirring (20S / time / 3S) to ensure the stability of the discharge concentration at the discharge port. The concentration is controlled at 45% to enter flotation for quality improvement. The ore is made to meet the particle size required by flotation, so that the useful minerals are basically dissociated into monomers for sorting. The less mud, iron and sulfur content, the easier it is to sort.

[0035] S2, slurry preparation: add 170g / t of butyl xanthate and 28g / t of No. 2 oil to the slurry, flotate and remove sulfide ore to obtain sulfide ore and desulfurized tailings; magnetically separate the desulfurized tailings to remove iron at a magnetic field strength of 0.3T to obtain iron concentrate and deironized tailings; concentrate and slurry the deironized tailings to 25%, add 280g / t of sodium carbonate, and stir for 8 minutes; add 150g / t of sodium hexametaphosphate, and stir for 5 minutes; add 100g / t of tributyl phosphate, and stir for 16 minutes; then add 800g / t of hydroxamic acid collector, and stir for 5 minutes; then add 50g / t of No. 2 oil, and stir for 2 minutes to obtain rougher concentrate and rougher tailings; S3. Aeration: Introduce air into the rougher concentrate to form a large number of bubbles.

[0036] S4. Separation: Hydrophobic mineral particles attach to the bubbles and float up to form a mineralized foam layer, while hydrophilic mineral particles remain in the slurry and discharge the mineralized foam to achieve the purpose of sorting.

[0037] (5) Secondary concentrate quality improvement: The flotation concentrate enters the physical concentrator (centrifuge) for secondary quality improvement, which can greatly improve the concentrate grade. The higher the feed grade, the higher the enrichment ratio. The tailings are fully recovered and circulated into the high-efficiency inclined plate thickener for concentration. The concentration is adjusted to 45% and then returned to the flotation machine for repeated screening to maximize the comprehensive recovery rate and realize the recovery and recycling of resources. Finally, the tin concentrate is dehydrated by concentrated filter press.

[0038] Comparative Example 1 The difference between this comparative example and Example 1 is that 28 g / t of No. 2 butter is not added.

[0039] Comparative Example 2 The difference between this comparative example and Example 1 is that 100 g / t of butyl xanthate and 70 g / t of No. 2 oil are added to the ore pulp.

[0040] Comparative Example 3 The difference between this comparative example and Example 1 is that no sodium carbonate is added.

[0041] Comparative Example 4 The difference between this comparative example and Example 1 is that sodium hexametaphosphate is not added.

[0042] Comparative Example 5 The difference between this comparative example and Example 1 is that 30 g / t of No. 2 oil is not added.

[0043] Performance Testing The tin concentrates prepared in Example 1 and Comparative Examples 1-5 were analyzed, and the results are shown in Table 1-2: Table 1 Comparative analysis of tin indicators (%)

[0044] Table 2 Comparison of tin concentrate particle size analysis (%)

[0045] As can be seen from Table 1, the method of the present invention has an excellent recovery rate.

[0046] By comparing Example 1 with Comparative Examples 1 to 6, it can be seen that the conditions and reagent ratios for flotation removal of sulfide ore and magnetic separation of iron removal in the present invention can significantly improve the recovery effect and also affect the distribution of the particle size of the tin concentrate.

[0047] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for recovering tin from secondary tailings, characterized in that: The following steps are involved: (1) Feeding: For the secondary tin tailings of fine-grained tin ore, they are first concentrated by a high-efficiency inclined plate thickener, and then fully stirred after the concentration is increased, and then enter the physical concentrator through a pressure stabilizing box; (2) Physical gravity separation: The centrifugal drum of the physical concentrator rotates horizontally, generating a centrifugal force field with uniform radial distribution on the inner surface of the drum. The slurry is fed to the inner surface of the drum by the feeding device and rotates along with the drum under the drive of the centrifugal drum. There is a slope along the axial direction of the inner surface of the centrifugal drum. The slurry flow rotates and flows along the axial direction at a certain flow rate. (3) Thickening: The physical concentrator discharges the high-density product to the separation device and discharges it into the concentrate receiving tank, and then enters the high-efficiency inclined plate thickener for thickening. The thickener discharge port is designed with a timed air pump mechanism to intake air and stir the product, and then enter the flotation for quality improvement; (4) Flotation process: The basic steps of flotation process include: S1. Feeding: The products with high specific gravity from the physical concentrator are discharged into the ore separation device and then into the concentrate receiving tank. They are then concentrated in the high-efficiency inclined plate thickener. The thickener discharge port is designed with a timed air pump mechanism to perform air intake and stirring to improve quality. S2, slurry adjustment: add 150-170g / t of butyl xanthate and 24-28g / t of No. 2 oil to the slurry, flotation remove sulfide ore to obtain sulfide ore and desulfurized tailings; magnetic separation of desulfurized tailings removes iron at a magnetic field strength of 0.2-0.3T to obtain iron concentrate and deironized tailings; concentrate and slurry the deironized tailings to 22-25%, add 250-280g / t of sodium carbonate, and stir for 5-8 minutes; add 120-150g / t of sodium hexametaphosphate, stir for 3-5 minutes; add 90-100g / t of tributyl phosphate, stir for 12-16 minutes; then add 700-800g / t of hydroxamic acid collector, stir for 3-5 minutes; then add 30-50g / t of No. 2 oil, stir for 1-2 minutes, and obtain rougher concentrate and rougher tailings; S3, Aeration: Introduce air into the rougher concentrate to form a large number of bubbles; S4. Separation: Hydrophobic mineral particles adhere to the bubbles and float up to form a mineralized foam layer, while hydrophilic mineral particles remain in the slurry and discharge the mineralized foam to achieve the purpose of separation; (5) Secondary concentrate upgrading: The flotation concentrate enters the physical concentrator for secondary upgrading to obtain tin concentrate. The tailings are fully recovered and circulated into the high-efficiency inclined plate thickener for concentration. The concentration is adjusted to 35%~45% and then returned to the flotation machine for repeated screening.

2. The tin recovery method of secondary tailings according to claim 1, characterized in that: The feed characteristics of the physical concentrator are a processing capacity of 1.3~1.8T dry ore / hour, a feed concentration of 14%~18%, and an initial feed velocity of 0.8~1m / s.

3. The tin recovery method of secondary tailings according to claim 1, characterized in that: The dosage of butyrrolidone is 150-170g / t slurry.

4. The tin recovery method of secondary tailings according to claim 3, characterized in that: The amount of No. 2 oil added for the first time is 24-28g / t slurry.

5. The tin recovery method of secondary tailings according to claim 1, characterized in that: The dosage of sodium carbonate is 250-280g / slurry.

6. The tin recovery method of secondary tailings according to claim 5, characterized in that: The dosage of sodium hexametaphosphate is 120-150g / t slurry.

7. The tin recovery method of secondary tailings according to claim 5, characterized in that: The dosage of tributyl phosphate is 90-100g / t slurry.

8. The tin recovery method of secondary tailings according to claim 5, characterized in that: The dosage of hydroxamic acid collector is 700-800g / t slurry.

9. The tin recovery method of secondary tailings according to claim 5, characterized in that: The amount of No. 2 oil added for the second time is 30-50g / t of slurry.

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