Beneficiation method for micro-fine particle low-grade tin ore

Abstract

The invention provides a beneficiation method of micro-fine particle low-grade tin ore. The beneficiation method comprises the following steps: (1) feeding; (2) physical reselection: a centrifugal drum of the physical concentrator rotates horizontally, and ore pulp is fed to the inner surface of the drum by an ore feeding device and is driven by the centrifugal drum to rotate along with the drum; (3) thickening; (4) the flotation process comprises the following steps: S1, feeding; s2, pulp mixing, wherein a flotation reagent is added into the ore pulp; the flotation reagents comprise a desulfurization flotation reagent and a floating tin flotation reagent, the desulfurization flotation reagent is added into the ore pulp for desulfurization flotation, and then the floating tin flotation reagent is added for floating tin flotation; s3, air inflation is carried out; s4, separating; and (5) secondary concentrate upgrading is conducted, specifically, flotation concentrate enters the physical concentrating machine again, secondary upgrading is conducted, and tin concentrate is obtained. According to the beneficiation method, the tin-containing grade of a tin concentrate product reaches 50% or above, and the comprehensive recovery rate reaches 55% or above.

Description

Technical Field

[0001] The invention belongs to the technical field of ore dressing, and in particular relates to a method for dressing micro-grained low-grade tin ore. Background Art

[0002] The beneficiation of fine-grained low-grade tin ores has important economic, environmental and social significance. Globally, high-quality, easily exploitable tin ore resources are gradually decreasing, while low-grade and fine-grained tin ore reserves are relatively abundant. Through effective beneficiation technology, more tin can be recovered from these resources and the overall resource utilization rate can be improved. By effectively treating low-grade ores and tailings, resources can be recycled and waste can be reduced, which is in line with the concept of circular economy. Efficient beneficiation technology can maximize the recovery of useful minerals and reduce the amount of tailings, thereby reducing pressure on the environment. Reasonable treatment of tailings can also prevent soil pollution and water pollution.

[0003] However, the particles of useful minerals (such as cassiterite) in fine-grained tin ore are very small, even reaching the micron level. This fine-grained distribution makes it extremely difficult to separate useful minerals from gangue minerals, increasing the complexity of separation. Fine-grained tin ore is often accompanied by a variety of other minerals, such as sulfides, iron minerals, silicates, etc. The presence of these associated minerals not only affects the selectivity of the beneficiation process, but may also lead to increased reagent consumption and decreased separation effect. The useful minerals and gangue minerals in fine-grained tin ore have little difference in density, magnetism, electrical properties, etc., resulting in poor results of traditional physical beneficiation methods such as gravity separation, magnetic separation, and electrostatic separation. In the flotation process, due to the large specific surface area and high surface energy of fine-grained minerals, mechanical inclusions and non-selective adsorption are prone to occur, making it difficult for collectors to effectively distinguish useful minerals from gangue minerals, reducing the selectivity and recovery rate of flotation.

[0004] Therefore, there is an urgent need for a beneficiation method for fine-grained low-grade tin ore. Summary of the invention

[0005] The purpose of the present invention is to provide a method for beneficiating fine-grained low-grade tin ore.

[0006] In order to achieve the above object, the present invention provides the following technical solutions: A method for beneficiating fine-grained low-grade tin ore 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.

[0007] (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: adding flotation reagents to the slurry; the flotation reagents include desulfurization flotation reagents and tin flotation reagents. First, the desulfurization flotation reagent is added to the slurry to perform desulfurization flotation, and then the tin flotation reagent is added to perform tin flotation; S3. Aeration: Introduce air into the slurry to form a large number of bubbles.

[0008] 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.

[0009] 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.

[0010] Furthermore, the desulfurization flotation reagent includes copper sulfate, butyl xanthate, ethyl thiocyanate and methyl isobutyl carbinol in a weight ratio of 1: (1.2-1.4): (0.5-0.7): (0.2-0.4).

[0011] Furthermore, the dosage of the desulfurization flotation agent is 1000-1200g / t slurry.

[0012] Further, the tin flotation reagent includes a suppressant, a collector and a frother in a weight ratio of (1.2-1.4): (0.2-0.5): 1; Furthermore, the dosage of the desulfurization flotation agent is 500-1000g / t slurry.

[0013] Furthermore, the inhibitor is styrene phosphonic acid.

[0014] Furthermore, the collector is 2-hydroxy-3-benzohydroxamic acid.

[0015] Furthermore, the foaming agent is methyl isobutyl carbinol.

[0016] Furthermore, in the physical concentrator, the ore slurry moves axially in a spiral shape on the inner surface of the drum; the large specific gravity 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 small specific gravity ore particles are unable to reach the bottom layer of the flow film due to the pulsating diffusion of the flow film, and are discharged along the slope of the drum together with the liquid phase to become small specific gravity products, and 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 specific gravity products into the ore separation device and discharge them into the concentrate receiving trough.

[0017] Compared with the prior art, the advantages and beneficial effects of the present invention are: 1. The present invention discloses a beneficiation method for fine-grained low-grade tin ore, including the steps of pre-ball mill heavy tailings, cyclone fine mud separation, shaking table (three times), secondary ball milling, sulfur flotation, tin flotation and the like. The present invention reclassifies and recovers the fine-grained tin tailings after separation, firstly concentrates the fine-grained tin ore (or tin tailings) through a thickener, fully stirs after increasing the concentration, and then enters the physical beneficiation machine through a pressure stabilizing (ore separation) box.

[0018] 2. Physical concentrator (centrifuge) used in the present invention: SL type centrifugal physical concentrator is a gravity separation equipment that utilizes the density difference between different ore particles to achieve the separation of ore particle groups. Centrifugal force is used to strengthen the flow film separation, which greatly improves the processing capacity of the equipment and reduces the recovery limit of the particle size. It has the characteristics of good sorting index, low recovery limit of fine metal low-grade tin ore, low energy consumption, and no pollution to the environment. The physical concentrator is used to preliminarily enrich the cassiterite, desludging is carried out during the enrichment process, and the tin metal in the fine particles is recovered, and the recovery rate can reach more than 80%.

[0019] 3. The flotation concentrate of the present invention enters the physical concentrator (centrifuge) for secondary quality improvement, and the concentrate grade is increased by 2 to 3 times on the original basis. The tailings produced after the quality improvement are recycled and enter the high-efficiency inclined plate thickener for concentration, and are repeatedly screened to maximize the comprehensive recovery rate, thereby realizing the recovery and recycling of resources. Finally, the tin concentrate is dehydrated by concentration and filter pressing.

[0020] 4. The reason why the present invention can significantly improve the tin recovery rate by using desulfurization flotation reagents (including copper sulfate, butyl xanthate, ethyl thiocyanate and methyl isobutyl carbinol, prepared in a weight ratio of 1: (1.2-1.4): (0.5-0.7): (0.2-0.4)) is mainly due to the synergistic effect between the reagents and their optimization of the mineral surface properties and the flotation process.

[0021] 5. The present invention uses a tin flotation agent, and the weight ratio of the tin flotation agent is (1.2-1.4): (0.2-0.5): 1 inhibitor, collector and frother. The optimization of this ratio and the selection of types can ensure that the agents cooperate with each other and play the best effect. The appropriate amount of inhibitor can effectively inhibit gangue minerals, and the reasonable ratio of collector and frother can improve the flotation performance of tin minerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The process flow chart of the beneficiation method of fine-grained low-grade tin ore of the present invention; 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 schematic diagram of the physical ore dressing machine from the front. DETAILED DESCRIPTION

[0023] 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.

[0024] Example 1 This embodiment provides a method for beneficiating fine-grained low-grade tin ore, 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.

[0025] 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.

[0026] (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 discharge port of the thickener is designed with a timed air pump mechanism to perform air intake and stirring (60S / time / 1S) 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.

[0027] (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.

[0028] 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 (60S / time / 1S) 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.

[0029] S2, slurry adjustment: adding flotation reagents to the slurry; the flotation reagents include desulfurization flotation reagents and tin flotation reagents. First, the desulfurization flotation reagent is added to the slurry to perform desulfurization flotation, and then the tin flotation reagent is added to perform tin flotation; The desulfurization flotation reagent includes copper sulfate, butyl xanthate, ethyl thiocyanate and methyl isobutyl carbinol in a weight ratio of 1:1.3:0.6:0.3. The dosage of the desulfurization flotation reagent is 1100g / t pulp. The floating tin flotation reagent includes an inhibitor, a collector and a frother in a weight ratio of 1.3:0.4:1; the dosage of the desulfurization flotation reagent is 800g / t pulp. The inhibitor is styrene phosphoric acid. The collector is 2-hydroxy-3-benzohydroxamic acid. The frother is methyl isobutyl carbinol.

[0030] S3. Aeration: Introduce air into the slurry to form a large number of bubbles.

[0031] 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.

[0032] (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.

[0033] Example 2 This embodiment provides a method for beneficiating fine-grained low-grade tin ore, 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.

[0034] 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.

[0035] (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 discharge port of the thickener is designed with a timed air pump mechanism to perform air intake and stirring (60S / time / 1S) 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.

[0036] 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, introduce bubbles into the slurry, and make the hydrophobic mineral particles adhere to the bubbles and float up, so as to achieve 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.

[0037] The basic steps of flotation process include: S1. Feeding: The products with high specific gravity (concentrate, high specific gravity metal) 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 (60S / time / 1S) 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.

[0038] S2, slurry adjustment: adding flotation reagents to the slurry; the flotation reagents include desulfurization flotation reagents and tin flotation reagents. First, the desulfurization flotation reagent is added to the slurry to perform desulfurization flotation, and then the tin flotation reagent is added to perform tin flotation; The desulfurization flotation reagent includes copper sulfate, butyl xanthate, ethyl thiocyanate and methyl isobutyl carbinol in a weight ratio of 1:1.2:0.5:0.4. The dosage of the desulfurization flotation reagent is 1200g / t pulp. The floating tin flotation reagent includes an inhibitor, a collector and a frother in a weight ratio of 1.4:0.5:1; the dosage of the desulfurization flotation reagent is 1000g / t pulp. The inhibitor is styrene phosphoric acid. The collector is 2-hydroxy-3-benzohydroxamic acid. The frother is methyl isobutyl carbinol.

[0039] S3. Aeration: Introduce air into the slurry to form a large number of bubbles.

[0040] 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.

[0041] (5) Secondary concentrate upgrading: The flotation concentrate enters the physical concentrator (centrifuge) for secondary upgrading. The tailings produced after upgrading are recycled and concentrated in the high-efficiency inclined plate thickener for repeated screening to maximize the comprehensive recovery rate and realize the recovery and recycling of resources. Finally, the tin concentrate is dehydrated by concentration and filter pressing.

[0042] Comparative Example 1 The difference between this comparative example and Example 1 is that the desulfurization flotation reagent includes copper sulfate, butyl xanthate, ethyl thiocyanate and methyl isobutyl carbinol in a weight ratio of 1:1:1:1.

[0043] Comparative Example 2 The difference between this comparative example and Example 1 is that the desulfurization flotation reagent includes copper sulfate, butyl xanthate and pine oil in a weight ratio of 1:1.2:0.4.

[0044] Comparative Example 3 The difference between this comparative example and Example 1 is that the tin flotation reagent includes a depressant, a collector and a frother in a weight ratio of 1:1:1. The dosage of the desulfurization flotation reagent is 800g / t pulp. The depressant is styrene phosphoric acid. The collector is 2-hydroxy-3-benzohydroxamic acid. The frother is methyl isobutyl carbinol.

[0045] Comparative Example 4 The difference between this comparative example and Example 1 is that the inhibitor is octylphenyl polyoxyethylene ether.

[0046] Comparative Example 5 The difference between this comparative example and Example 1 is that the collector is salicylic hydroxamic acid.

[0047] Comparative Example 6 The difference between this comparative example and Example 1 is that the foaming agent is pine oil.

[0048] Performance Testing The tin concentrates prepared in Example 1 and Comparative Examples 1-6 were analyzed, and the results are shown in Table 1-2.

[0049] Table 1 Comparative analysis of tin indicators (%)

[0050] Table 2 Comparison of tin concentrate particle size analysis (%)

[0051] As can be seen from Table 1, the method of the present invention has an excellent recovery rate.

[0052] By comparing Example 1 with Comparative Examples 1-2, it can be seen that the desulfurization flotation agent of the present invention can significantly improve the recovery effect.

[0053] By comparing Example 1 with Comparative Examples 3 to 6, it can be seen that the tin flotation agent can not only improve the recovery rate, but also affect the distribution of the particle size of the tin concentrate.

[0054] 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 beneficiating fine-grained low-grade tin ore, characterized in that: The following steps are involved: (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 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 perform air intake and stirring. The concentration is controlled at 35%~45% and enters 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 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: adding flotation reagents to the slurry; the flotation reagents include desulfurization flotation reagents and tin flotation reagents. First, the desulfurization flotation reagent is added to the slurry to perform desulfurization flotation, and then the tin flotation reagent is added to perform tin flotation; S3, Aeration: Introduce air into the slurry 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 beneficiation method of fine-grained low-grade tin ore 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 beneficiation method of fine-grained low-grade tin ore according to claim 1, characterized in that: The desulfurization flotation reagent includes copper sulfate, butyl xanthate, ethyl thiocyanate and methyl isobutyl carbinol in a weight ratio of 1: (1.2-1.4): (0.5-0.7): (0.2-0.4).

4. The beneficiation method of fine-grained low-grade tin ore according to claim 3, characterized in that: The dosage of desulfurization flotation agent is 1000-1200g / t pulp.

5. The beneficiation method of fine-grained low-grade tin ore according to claim 1, characterized in that: The tin flotation reagents include inhibitors, collectors and frothers in a weight ratio of (1.2-1.4): (0.2-0.5):

1.

6. The beneficiation method of fine-grained low-grade tin ore according to claim 5, characterized in that: The dosage of desulfurization flotation agent is 500-1000g / t pulp.

7. The beneficiation method of fine-grained low-grade tin ore according to claim 5, characterized in that: The inhibitor is styrene phosphonic acid.

8. The beneficiation method of fine-grained low-grade tin ore according to claim 5, characterized in that: The collector is 2-hydroxy-3-benzohydroxamic acid.

9. The beneficiation method of fine-grained low-grade tin ore according to claim 5, characterized in that: The foaming agent is methyl isobutyl carbinol.

10. The beneficiation method of fine-grained low-grade tin ore according to claim 1, characterized in that: In the physical ore concentrator, the ore slurry moves axially in a spiral shape on the inner surface of the drum; the large specific gravity ore particles are centrifugally settled to 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 small specific gravity ore particles cannot 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 together with the liquid phase to become small specific gravity products, and are discharged into the tailings receiving trough through the ore separation device; when the ore feeding is suspended, the flushing device will flush the high specific gravity products to the ore separation device and discharge them into the concentrate receiving trough.

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