Beneficiation method for intensively recovering cassiterite from low-grade tin tailings

Abstract

The invention discloses a beneficiation method for intensively recovering cassiterite from low-grade tin tailings, and belongs to the technical field of beneficiation. The low-grade tin tailings are separated through a spiral chute, coarse-grained gangue is thrown out, then separation is conducted through a shaking table, and medium-grained cassiterite shaking table concentrate and fine-grained cassiterite shaking table tailings are obtained; after the fine-fraction cassiterite table tailings are subjected to magnetic separation iron removal and reverse flotation desulfurization in sequence, fine-fraction cassiterite flotation is conducted through a hydroximic acid flotation reagent system and a positive-pressure dissolved-air type flotation column, and fine-fraction cassiterite concentrate is obtained; and the fine-fraction cassiterite concentrate is subjected to centrifugal treatment, and fine-fraction cassiterite centrifugal concentrate is obtained. The method is low in cost and high in recovery efficiency, the high-grade fine-fraction cassiterite concentrate can be obtained, and the method has important significance on efficient development and utilization of tin resources.

Description

Technical Field

[0001] This invention relates to a beneficiation method for low-grade tin tailings, and more particularly to a beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings, belonging to the field of mineral processing technology. Background Technology

[0002] Tin is widely used in aerospace, electronics and other fields. Cassiterite is the main raw material for industrial tin extraction. However, due to its brittle nature, cassiterite is prone to mudification and over-grinding during crushing and grinding. Furthermore, traditional cassiterite gravity separation processes cannot effectively recover this portion of low- to medium-sized cassiterite, resulting in a large amount of cassiterite entering the tailings and causing a serious waste of tin resources.

[0003] Cassiterite tailings resources are characterized by low grade, fine particle size, and complex associated relationships. There are already reports on the recovery of fine-grained cassiterite. For example, Chinese patent CN117583116B discloses a method for recovering fine-grained cassiterite. This method uses a flotation column-magnetic separation-shaking table process to sequentially perform flotation, magnetic separation, and shaking table treatment of low-grade fine-grained cassiterite ore, achieving effective enrichment and recovery of fine-grained cassiterite. However, this method directly performs flotation treatment on the raw ore, resulting in a very large flotation throughput and limited enrichment effect; furthermore, it consumes a large amount of flotation reagents, leading to high recovery costs. Another example is Chinese patent CN1810381A, which discloses a beneficiation method for tin polymetallic sulfide ore tailings. This method uses spiral classification and spiral sluice treatment on the desulfurization flotation tailings. Based on this, multiple flotation stages are performed on products of different particle sizes to recover fine-grained cassiterite. The pre-classification and gravity separation treatment in this process can effectively reduce the throughput of subsequent flotation, effectively lowering the cost of flotation. However, due to limitations in flotation equipment, the effectiveness of this method in the flotation and recovery of fine-grained cassiterite needs further improvement. Summary of the Invention

[0004] In view of the technical problems of high cost and low efficiency in the recovery of low-grade cassiterite tailings with fine particle size in the existing technology, the purpose of this invention is to provide a beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings. This method is low in cost and high in recovery efficiency, and can obtain high-grade fine-grained cassiterite concentrate, which is of great significance for the efficient development and utilization of tin resources.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings, the method comprising the following steps:

[0006] 1) After the low-grade tin tailings are slurry-treated, the coarse gangue is first removed by spiral chute separation, and then the medium-grade cassiterite shaker concentrate and fine-grade cassiterite shaker tailings are obtained by shaking table separation.

[0007] 2) After the fine-grained cassiterite tailings from the shaking table are successively subjected to magnetic separation for iron removal and reverse flotation for desulfurization, fine-grained cassiterite flotation is carried out to obtain fine-grained cassiterite concentrate;

[0008] The fine-grained cassiterite flotation process employs a hydroxyoxime acid flotation reagent system and a positive pressure dissolved gas flotation column. The positive pressure dissolved gas flotation column uses a positive pressure dissolved gas-reduced pressure release method to generate micro-nano bubbles for continuous flotation. During the flotation process, the dissolved gas pressure of the positive pressure dissolved gas flotation column is controlled at 0.4~0.5MPa, the release pressure at 0.15~0.2MPa, the circulation flow rate at 10~15L / min, the aeration rate at 1~2L / min, and the foam layer thickness is maintained at 10~20cm.

[0009] 3) The fine-grained cassiterite concentrate is centrifuged to obtain fine-grained centrifuged cassiterite concentrate.

[0010] The beneficiation method for low-grade tin tailings provided by this invention employs a combination of gravity separation and flotation. First, gravity separation is used to recover medium-grained cassiterite concentrate while simultaneously pre-enriching fine-grained cassiterite. During gravity separation, a spiral sluice + shaking table method is used for separation. The spiral sluice pre-discards coarse-grained gangue minerals, and then the shaking table separation achieves the recovery of medium-grained cassiterite. The fine-grained cassiterite enriched in the shaking table tailings can be recovered through subsequent flotation. The recovery of medium-grained cassiterite effectively reduces the amount of minerals processed in subsequent flotation processes, thereby reducing the amount of flotation reagents used and lowering flotation costs. The tailings from the shaking table mainly contain fine-grained cassiterite of -0.015mm. The key to this invention is the use of a positive-pressure dissolved air flotation column to recover fine-grained cassiterite through micro-nano bubble flotation. The positive-pressure dissolved air flotation column generates a large number of micro-nano bubbles through positive-pressure dissolved air and depressurization release, which can enhance the mixing efficiency between bubbles, collectors, and fine-grained minerals. This is beneficial for the selective precipitation of micro-nano bubbles on the surface of fine-grained cassiterite and the adsorption of collectors on the surface of fine-grained cassiterite minerals, thereby reducing collector consumption and improving the flotation efficiency of fine-grained cassiterite.

[0011] In the fine-grained cassiterite flotation process of this invention, the circulation flow rate of the positive pressure dissolved air flotation column mainly affects the mineralization efficiency of bubbles and refractory ores. The dissolved air pressure, release pressure, and aeration rate mainly affect the effect of micro-nano bubbles generated by dissolution and release, and thus affect the bubble size distribution within the flotation column. Under optimized circulation flow rate, dissolved air pressure, release pressure, and aeration rate, it can be ensured that the proportion of bubbles smaller than 0.1 mm within the positive pressure dissolved air flotation column exceeds 70%. The thickness of the froth layer mainly affects the secondary enrichment of minerals. Based on the cassiterite flotation effect, a froth layer thickness of 10-20 cm can be selected for the effective enrichment of fine-grained cassiterite concentrate.

[0012] As a preferred embodiment, the low-grade tin tailings particle size meets the following requirements: the mass percentage of particles with a diameter of -0.075 mm is 40-50%, and the mass percentage of particles with a diameter of -0.015 mm is 20-30%. As another preferred embodiment, the tin grade in the low-grade tin tailings is ≤0.12%. The low-grade tin tailings of this invention not only have a low tin grade but also a high proportion of fine particles with a diameter of -0.015 mm. Generally, such fine-grained minerals have a low probability of colliding with air bubbles during flotation and are difficult to be captured by air bubbles; this is precisely one of the problems that this invention aims to solve.

[0013] As a preferred embodiment, the feed mass concentration of the spiral chute is in the range of 15~25%.

[0014] As a preferred embodiment, the grade of the medium-grained cassiterite shaker concentrate is greater than 5%.

[0015] As a preferred embodiment, the feed concentration of the shaker is 15-25%.

[0016] As a preferred embodiment, the hydroxamic acid flotation reagent system includes a hydroxamic acid collector, a pH adjuster, a depressant, and a frother. As a more preferred embodiment, the hydroxamic acid collector includes at least one of benzoyl hydroxamic acid, alkyl hydroxamic acid, salicylic acid, benzoyl hydroxamic acid-lead coordination collector, alkyl hydroxamic acid-lead coordination collector, and salicylic acid-lead coordination collector. As a more preferred embodiment, the pH adjuster includes sodium carbonate. As a more preferred embodiment, the depressant is salinized water glass. Salinized water glass, such as aluminum ion-modified water glass (aluminum sulfate-water glass), mainly inhibits silicate minerals such as quartz and mica. As a preferred embodiment, the frother includes terpineol and / or tributyl methyl phosphate. The present invention selects a hydroxamic acid flotation reagent system to improve the flotation selectivity and flotation efficiency for cassiterite minerals.

[0017] As a preferred embodiment, the fine-grained cassiterite flotation includes one roughing stage, two cleaning stages, and one scavenging stage.

[0018] As a preferred option, the reagent system for the roughing process is as follows: pH adjuster dosage is 500~1000g / t (relative to each ton of dry ore), hydroxamic acid collector dosage is 250~500g / t, frother dosage is 20~30g / t, and inhibitor dosage is 100~200g / t.

[0019] As a preferred option, the selected formulation is as follows: the inhibitor dosage is 50~100g / t.

[0020] In the cassiterite flotation process of this invention, the total amount of inhibitor used in the roughing and cleaning stages is 400~600g / t (relative to each ton of dry ore).

[0021] As a preferred embodiment, the reagent system for scavenging is as follows: the amount of collector is 125~250g / t; wherein, the scavenging concentrate is returned to the roughing process to form a closed circuit, and the scavenging tailings are the final tailings.

[0022] As a preferred embodiment, the centrifugation process separates fine-grained cassiterite concentrate with a grade greater than 15%. During the centrifugation process, the centrifuge speed is 300~600 r / min.

[0023] In this invention, coarse particle size mainly refers to the particle size of +0.075 mm, medium particle size mainly refers to the particle size of +0.038 mm to -0.075 mm, and fine particle size mainly refers to the particle size of -0.038 mm. "-" indicates the undersize material obtained by sieve grading, and "+" indicates the oversize material obtained by sieve grading.

[0024] Compared with the prior art, the beneficial technical effects of this invention are as follows:

[0025] (1) The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings provided by the present invention adopts the beneficiation method of "gravity separation + flotation". It makes full use of the advantages of gravity separation and flotation. First, spiral sluice and shaking table are used to realize the pre-disposal of tin tailings and the recovery of medium-grained cassiterite and the enrichment of fine-grained cassiterite. The recovery of medium-grained cassiterite can reduce the processing volume of subsequent flotation, reduce the amount of flotation reagents, reduce the cost of tin tailings development, and realize the efficient and comprehensive recovery of tin in tin tailings.

[0026] (2) The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings provided by the present invention generates a large number of micro-nano bubbles by using a positive pressure dissolved gas flotation column in the manner of positive pressure dissolved gas-depressurization release, and achieves selective precipitation of micro-nano bubbles on the surface of target minerals, which effectively improves the mineralization efficiency of flotation equipment for fine-grained cassiterite minerals.

[0027] (3) The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings provided by the present invention effectively improves the mixing efficiency of bubbles, collectors and fine-grained minerals by adopting a positive pressure dissolved air flotation column, promotes the adsorption of collectors on the surface of fine-grained target minerals, further reduces the consumption of collectors, and improves the flotation recovery efficiency of cassiterite.

[0028] (4) The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings provided by the present invention fundamentally overcomes the defect of low collision probability between fine minerals and bubbles by adopting a positive pressure dissolved air flotation column, and has significant advantages, especially in the flotation recovery of -0.015mm fine minerals. Attached Figure Description

[0029] Figure 1This is a flow chart of the mineral processing technology for enhanced recovery of cassiterite from low-grade tin tailings according to the present invention.

[0030] Figure 2 This is a schematic diagram of the foamer of the positive pressure dissolved air flotation column of the present invention; wherein, 1 is the air inlet, 2 is the jet tube, 3 is the static mixer, and 4 is the diffuser. Detailed Implementation

[0031] The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings of the embodiments of the present invention. The specific embodiments below are intended to further illustrate the content of the present invention, rather than to limit the scope of protection of the claims.

[0032] Furthermore, the technical solutions of the various embodiments of the invention can be combined with each other, but only if they are based on the ability of a person skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0033] The key difference between the positive pressure dissolved air flotation column of this invention and the existing conventional aerated flotation column lies in the use of a positive pressure dissolved air foamer. See the specific structure below. Figure 2 The column, from the gas inlet to the gas outlet, consists of a gas feed port 1, a jet pipe 2, a static mixer 3, and a diffuser 4. During operation, the slurry, pumped by a slurry pump, enters the feed port of the positive pressure dissolved air frother at a certain pressure. Simultaneously, air is injected from the gas feed port 1. Both are sprayed through the jet pipe 2 into the pipe equipped with the static mixer 3. An appropriate dissolved air pressure is maintained within the pipe between the jet pipe 2 and the diffuser 4. Under the action of the static mixed gas, the air is efficiently dissolved in the slurry, forming saturated dissolved air water. Subsequently, the saturated dissolved air water is discharged through the diffuser 4. The diffuser has a funnel-shaped structure, which enables depressurization, promoting the selective precipitation of micro- and nano-bubbles on the surface of hydrophobic fine-particle target minerals, thereby significantly improving the mineralization efficiency of fine-particle flotation.

[0034] Example 1

[0035] Using low-grade tin tailings from Jiangxi Province as raw material, a cassiterite recovery enhancement test was conducted using the gravity-flotation-gravity beneficiation process. As shown in Table 1, the tin grade of the tailings was 0.11%. Of this, 60.02% tin was distributed in the -0.038mm particle size product, and 49.56% Sn was distributed in the -0.015mm particle size product. Meanwhile, the yield of the +0.075mm product reached approximately 50%, but the tin distribution rate in the +0.075mm product was approximately 20%. Based on this, see [further details omitted]. Figure 1 The following is a detailed experimental procedure for the enhanced flotation recovery of cassiterite from tin tailings:

[0036] (1) The low-grade tin tailings were pre-mixed into a slurry with a concentration of 20%, and the low-grade tin tailings were pre-discarded for coarse particles (mainly +0.075mm particle size) and pre-enriched for cassiterite using a spiral chute with a pitch of 60cm. This yielded a tin pre-enriched concentrate with a grade of 0.192% and a recovery rate of 72.03% and a tailings product with a grade of 0.058% and a yield of 56.25%, thus realizing the pre-discarding of low-grade coarse particles and the acquisition of tin pre-enriched ore.

[0037] (2) The concentration of the obtained tin pre-enriched ore was adjusted to 25%, and the slurry was treated with a shaking table to obtain medium-sized cassiterite concentrate (mainly +0.038mm~-0.075mm particle size) with a grade of 5.070% and a comprehensive recovery rate of 11.14%, and fine-grained shaking table tailings (mainly -0.038mm particle size) with a tin grade of 0.167%.

[0038] (3) The tailings from the shaking table are subjected to magnetic separation to remove iron under a magnetic field strength of 0.8T;

[0039] (4) The magnetic separation tailings are concentrated to a pulp concentration of 35%, and desulfurization roughing treatment is carried out using 200g / t activator copper sulfate, 100g / t collector butyl xanthate and 28g / t frother terpineol respectively. The desulfurization roughing tailings are further desulfurized and scavenged using 100g / t activator copper sulfate, 50g / t collector butyl xanthate and 14g / t frother terpineol.

[0040] (5) Subsequently, 1000 g / t of sodium carbonate, 300 g / t of aluminum sulfate-water glass (the mass ratio of aluminum sulfate to water glass is 1:1), 500 g / t of benzohydroxyxamic acid-lead coordination collector and 20 g / t of pine oil were added to the cassiterite flotation raw ore in sequence and the slurry was prepared for 30 min.

[0041] (6) The prepared slurry is pumped into a positive pressure dissolved air flotation column to carry out one flotation roughing, two flotation cleaning and one flotation scavenging of cassiterite raw ore. The dissolved air pressure of the flotation column is controlled at 0.4 MPa, the release pressure is 0.2 MPa, the circulation flow rate is 13 L / min, the aeration rate is 1.5 L / min, and the foam layer thickness is 10~20 cm. Finally, a fine cassiterite flotation concentrate with a grade of 7.410% and a comprehensive recovery rate of 50.03% and a fine cassiterite flotation tailings with a grade of 0.021% are obtained.

[0042] (7) Finally, the cassiterite flotation concentrate with a grade of 7.410% was centrifuged to obtain a high-grade fine-grained cassiterite centrifuged concentrate with a tin grade of 16.290% and a comprehensive recovery rate of 46.09%.

[0043] The beneficiation process for enhanced recovery of cassiterite from low-grade tailings yields medium-grained cassiterite concentrate with a tin grade of 5.070% and a recovery rate of 11.14%, and high-grade fine-grained centrifugal concentrate with a tin grade of 16.290% and a recovery rate of 46.09%. The overall tin recovery rate can reach about 60%, achieving efficient recovery and utilization of tin resources from low-grade tin tailings.

[0044]

[0045] Example 2

[0046] See Figure 1 A beneficiation process for enhanced cassiterite recovery from low-grade tin tailings was used to conduct a cassiterite recovery test on a low-grade tin tailings ore in Guangxi Zhuang Autonomous Region. As shown in Table 1, the tin grade in the raw ore was approximately 0.14%, with tin mainly distributed in the -0.015mm particle size product, achieving a distribution rate of 64.72%. Simultaneously, the yield of the +0.075mm product in the raw ore reached 41.67%, with tin distribution in the +0.075mm product approximately 10.65%. The specific experimental procedure is as follows:

[0047] 1) The low-grade tin tailings were pre-mixed into a 20% slurry, and coarse particles (mainly +0.075mm size) were pre-discarded and cassiterite was pre-enriched using a spiral sluice with a pitch of 40cm. This yielded a tin pre-enriched concentrate with a grade of 0.220% and a comprehensive recovery rate of 86.18%, and a tailings product with a grade of 0.045% and a yield of 43.96%. This process achieved the pre-discarding of low-grade coarse particles and the acquisition of tin pre-enriched ore.

[0048] (2) The concentration of the obtained tin pre-enriched ore was adjusted to 18%, and the slurry was treated with a shaking table to obtain medium-sized cassiterite concentrate (mainly +0.038mm~-0.075mm particle size) with a grade of 5.270% and a comprehensive recovery rate of 10.07% and fine-grained shaking table tailings (mainly -0.038mm particle size) with a tin grade of 0.192%;

[0049] (3) The tailings from the shaking table are subjected to magnetic separation to remove iron under a magnetic field strength of 0.8T;

[0050] (4) The magnetic separation tailings are concentrated to a pulp concentration of 35%, and desulfurization roughing treatment is carried out using 200g / t activator copper sulfate, 100g / t collector butyl xanthate and 28g / t frother terpineol respectively. The desulfurization roughing tailings are further desulfurized and scavenged using 100g / t activator copper sulfate, 50g / t collector butyl xanthate and 14g / t frother terpineol to obtain cassiterite flotation raw ore.

[0051] (5) Subsequently, 1500 g / t of sodium carbonate, 300 g / t of aluminum sulfate-water glass (the mass ratio of aluminum sulfate to water glass is 1:1), 500 g / t of benzohydroxyxamic acid-lead coordination collector and 20 g / t of pine oil were added to the cassiterite flotation raw ore in sequence and the slurry was prepared for 30 min.

[0052] (6) The prepared slurry is pumped into a positive pressure dissolved air flotation column to carry out one roughing flotation, two cleaning flotation, and one scavenging flotation of the cassiterite raw ore. The dissolved air pressure of the flotation column is controlled at 0.5 MPa, the release pressure at 0.15 MPa, the circulation flow rate at 13 L / min, the aeration rate at 1.5 L / min, and the foam layer thickness at 10-20 cm. Finally, a fine-grained cassiterite flotation concentrate with a Sn grade of 10.070% and a comprehensive recovery rate of 59.24% is obtained, and the Sn grade of the tailings can be reduced to 0.032%.

[0053] (7) Finally, the cassiterite flotation concentrate with a grade of 10.070% was centrifuged to obtain a high-grade fine-grained cassiterite centrifuged concentrate with a tin grade of 26.280% and a recovery rate of 54.94%.

[0054] The beneficiation process for enhanced recovery of cassiterite from low-grade tailings yields medium-grade cassiterite concentrate with a grade of 5.270% and a recovery rate of 10.07%, and high-grade fine-grained centrifugal concentrate with a grade of 26.280% and a recovery rate of 54.94%. The overall tin recovery rate can reach about 65%, achieving efficient recovery and utilization of tin resources from low-grade tin tailings.

[0055]

[0056] Comparison Example 1

[0057] Using a low-grade tin tailings ore from Jiangxi Province (Example 1) as raw material, an enhanced cassiterite recovery experiment was conducted using a "heavy (single spiral chute)-float-heavy" process.

[0058] (1) The low-grade tin tailings were pre-mixed into a slurry with a concentration of 20%, and the low-grade tin tailings were pre-discarded for coarse particles (mainly +0.075mm particle size) and pre-enriched for cassiterite using a spiral chute with a pitch of 60cm. This yielded a tin pre-enriched concentrate with a grade of 0.198% and a recovery rate of 73.68% and a tailings product with a grade of 0.055% and a yield of 57.92%, thus realizing the pre-discarding of low-grade coarse particles and the acquisition of tin pre-enriched ore.

[0059] (2) Subsequently, a magnetic field strength of 0.8T was used to perform magnetic separation to remove iron from the tin pre-enriched ore, and magnetic tailings were obtained.

[0060] (3) The magnetic separation tailings are concentrated to a pulp concentration of 35%, and then desulfurized and roughed using 200 g / t activator copper sulfate, 100 g / t collector butyl xanthate and 28 g / t frother terpineol. The desulfurized roughed tailings are further desulfurized and scavenged using 100 g / t activator copper sulfate, 50 g / t collector butyl xanthate and 14 g / t frother terpineol to obtain cassiterite flotation ore.

[0061] (4) Subsequently, 1000 g / t of sodium carbonate, 400 g / t of aluminum sulfate-water glass (the mass ratio of aluminum sulfate to water glass is 1:1), 500 g / t of benzohydroxyxamic acid-lead coordination collector and 20 g / t of pine oil were added to the cassiterite flotation raw ore in sequence and the slurry was prepared for 3 min.

[0062] (5) The prepared slurry is pumped into the positive pressure dissolved air flotation column to carry out one flotation roughing, two flotation cleaning and one flotation scavenging of cassiterite raw ore. The dissolved air pressure of the flotation column is controlled at 0.4 MPa, the release pressure is 0.2 MPa, the circulation flow rate is 13 L / min, the aeration rate is 1.5 L / min, and the foam layer thickness is 10~20 cm. Finally, cassiterite flotation concentrate with a grade of 5.670% and a comprehensive recovery rate of 53.76% and cassiterite flotation tailings with a grade of 0.030% are obtained.

[0063] (6) Finally, the cassiterite flotation concentrate with a grade of 5.670% was centrifuged to obtain a cassiterite centrifuged concentrate with a tin grade of 9.390% and a comprehensive recovery rate of 46.82%.

[0064] Compared to Example 1, this comparative example did not include a shaking table operation in the gravity separation process before flotation, and medium-sized cassiterite particles were not recovered in advance. This resulted in an increase in the tin grade of the flotation column tailings from 0.021% in Example 1 to 0.030%, exacerbating tailings runoff and reducing the overall tin recovery rate. Furthermore, it resulted in the final centrifuged cassiterite concentrate containing medium-sized cassiterite particles with low degree of liberation, leading to a tin grade of only 9.390% in the centrifuged concentrate, significantly lower than the 16.290% in Example 1.

[0065] Comparison Example 2

[0066] Using low-grade tin tailings from Jiangxi Province (Example 1) as raw material, an enhanced cassiterite recovery test was conducted using a gravity-flotation-gravity process. The cassiterite flotation employed a conventional aerated flotation column.

[0067] Steps (1) to (5) are the same as steps (1) to (5) in Example 1;

[0068] (6) The prepared slurry is pumped into the aerated flotation column to carry out one flotation roughing, two flotation cleaning and one flotation scavenging of the cassiterite raw ore. The aeration rate of the aerated flotation column is controlled at 1.5L / min and the thickness of the froth layer is 10~20cm. Finally, a fine cassiterite flotation concentrate with a grade of 5.530% and a comprehensive recovery rate of 44.00% and a fine cassiterite flotation tailings with a grade of 0.039% are obtained.

[0069] (7) Finally, the cassiterite flotation concentrate with a grade of 5.53% was centrifuged to obtain a high-grade fine-grained cassiterite centrifuged concentrate with a tin grade of 14.90% and a comprehensive recovery rate of 38.58%.

[0070] Compared to Example 1, this comparative example uses a conventional aerated flotation column for cassiterite flotation. Compared to a positive pressure dissolved air flotation column, this device only achieves collision and adhesion between bubbles and mineral particles through countercurrent mineralization. However, most cassiterite particles are at the fine particle level, resulting in a low probability of collision with bubbles. This leads to low flotation efficiency for fine cassiterite particles in the aerated flotation column, with significant tailing of fine cassiterite particles, ultimately resulting in a comprehensive recovery rate of only 44.00% for cassiterite concentrate. In contrast, the positive pressure dissolved air flotation column generates a large number of micro-nano bubbles through positive pressure dissolved air-depressurization release, achieving selective precipitation of micro-nano bubbles on the surface of the target mineral. This device fundamentally solves the problem of low collision probability between fine mineral particles and bubbles, while further improving the selectivity of the flotation equipment. Therefore, compared to the traditional aerated flotation column, the positive pressure dissolved air flotation column has a superior selective enrichment effect, resulting in a higher grade and recovery rate of fine cassiterite concentrate.

Claims

1. A beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings, characterized in that: Includes the following steps: 1) After the low-grade tin tailings are slurry-treated, the coarse gangue is first removed by spiral chute separation, and then the medium-grade cassiterite shaker concentrate and fine-grade cassiterite shaker tailings are obtained by shaking table separation. 2) After the fine-grained cassiterite tailings from the shaking table are successively subjected to magnetic separation for iron removal and reverse flotation for desulfurization, fine-grained cassiterite flotation is carried out to obtain fine-grained cassiterite concentrate; The fine-grained cassiterite flotation process employs a hydroxyoxime acid flotation reagent system and a positive pressure dissolved gas flotation column. The positive pressure dissolved gas flotation column uses a positive pressure dissolved gas-reduced pressure release method to generate micro-nano bubbles for continuous flotation. During the flotation process, the dissolved gas pressure of the positive pressure dissolved gas flotation column is controlled at 0.4~0.5MPa, the release pressure at 0.15~0.2MPa, the circulation flow rate at 10~15L / min, the aeration rate at 1~2L / min, and the foam layer thickness is maintained at 10~20cm. 3) The fine-grained cassiterite concentrate is centrifuged to obtain fine-grained centrifuged cassiterite concentrate.

2. The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 1, characterized in that: The low-grade tin tailings have the following particle size requirements: 40-50% of the particles are -0.075mm and 20-30% are -0.015mm.

3. A beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 1 or 2, characterized in that: The tin grade in the low-grade tin tailings is ≤0.12%.

4. The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 1, characterized in that: The feed concentration of the spiral chute is in the range of 15-25%.

5. The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 1, characterized in that: The grade of the medium-grained cassiterite shaker concentrate is greater than 5%.

6. The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 1, characterized in that: The hydroxamic acid flotation reagent system includes hydroxamic acid collectors, pH adjusters, inhibitors, and foaming agents; The hydroxamic acid collectors include at least one of benzohydroxyxamic acid, alkylhydroxyxamic acid, salicylic acid, benzohydroxyxamic acid-lead coordination collector, alkylhydroxyxamic acid-lead coordination collector, and salicylic acid-lead coordination collector. The pH adjuster includes sodium carbonate; The inhibitor includes saline water glass; The foaming agent includes terpineol and / or tributyl methyl phosphate.

7. A beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 1 or 6, characterized in that: The fine-grained cassiterite flotation includes one roughing stage, two cleaning stages, and one scavenging stage.

8. The beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 7, characterized in that: The reagent system for the roughing process is as follows: pH adjuster dosage is 500~1000g / t, hydroxamic acid collector dosage is 250~500g / t, foaming agent dosage is 20~30g / t, and inhibitor dosage is 100~200g / t. The selected formulation is as follows: the inhibitor dosage is 50~100g / t; The chemical formulation for the scavenging process is as follows: the amount of collector used is 125~250g; In this process, the scavenging concentrate is returned to the roughing process to form a closed circuit, and the scavenging tailings are the final tailings.

9. A beneficiation method for enhanced recovery of cassiterite from low-grade tin tailings according to claim 1, characterized in that, The centrifugation process separates fine-grained cassiterite concentrate with a grade greater than 15%.

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