Application of phosphonated starch in selective flocculation desliming of fine-grained columbite

Abstract

The application discloses application of phosphonated starch in selective flocculation desliming of fine-grained niobium ore, and a structural formula of the phosphonated starch is composed of a phosphonate group and a polysaccharide group of starch, the polysaccharide group is a high molecular chain formed by connecting multiple six-carbon sugar units through a glycosidic bond, and the phosphonate group is used for chelating with Nb 5+ A chelation reaction occurs, the polysaccharide group high molecular chain produces flocculation, and fine-grained gangue minerals are removed by selective flocculation. The phosphonate group of the phosphonated starch in the application chelates with exposed niobium ions on the surface of niobium minerals, so that the phosphonated starch is selectively adsorbed on the surface of the niobium minerals, the polysaccharide high molecular chain plays a bridging and sweeping role, fine-grained gangue slimes can be significantly removed by the method of selective flocculation desliming, the grade of Nb2O5 is improved, and the method has important significance for efficient recycling of fine-grained niobium ore.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, and in particular relates to the application of phosphorylated starch in selective flocculation and desliming of fine-grained niobium ore. Background Technology

[0002] Niobium, as a strategic rare metal, is widely used in key materials fields such as metallurgy, aerospace, superconductivity, atomic energy, electronics, and optics, playing a vital role in national economic development. Niobium often occurs alongside rare earth elements and tantalum, exhibiting fine and dispersed mineral distribution, poor occurrence conditions, low grade, large beneficiation volume, and poor selectivity, all of which pose challenges to the recovery and utilization of niobium resources. Solving the problem of difficult recovery and utilization of fine-grained niobium resources has become a top priority in current niobium beneficiation.

[0003] Due to the complex properties of niobium ore, a single beneficiation process cannot yield qualified concentrate products. It is often necessary to employ one or more methods, such as magnetic separation, gravity separation, flotation, and electrostatic separation, to separate various minerals. A Chinese journal article, "The Araxsa Niobium Mine in Brazil," discloses that in the weathered residual laterite ore mined from the Araxsa mine in Brazil, pyrochlore accounted for 4.6% and magnetic iron minerals for 51%. The ore was first subjected to weak magnetic separation to obtain an iron concentrate with an Fe grade of 67%. The tailings from the magnetic separation were then deslimed using a three-stage hydrocyclone system, removing approximately 12% of the slime. The sediment produced during the desliming process was then subjected to flotation. Hydrochloric acid was used as an adjuster to adjust the pulp pH to 2.5–3.5, sodium silicate was used as an activator, and amine cationic reagents were used as collectors. Through a roughing and cleaning process, a niobium concentrate with an Nb₂O₅ grade of 55%–60% was obtained. The Chinese journal article "Practice of Comprehensive Utilization of Mineral Resources in Yichun Tantalum-Niobium Mine" discloses that the tantalum-niobium production process in Yichun, Jiangxi Province, involves ore washing, three-stage crushing, one-stage grinding, and separate beneficiation of primary niobium. A wet magnetic separation-gravity separation combined process is used to directly obtain a portion of qualified tantalum-niobium concentrate. The gravity separation tailings are transferred to a second-stage ball mill and then subjected to a combined gravity separation using spiral sluice and shaking table to obtain another portion of tantalum-niobium concentrate. The final tantalum-niobium concentrate (TaNb)₂O₅ grade is 46%–50%, and the recovery rate is 46%–48%. The Chinese journal article "Current Status and New Ideas for Comprehensive Utilization of Rare Earth and Niobium Resources in Bayan Obo" discloses that the lean oxide ore in the main eastern mine of the Baotou polymetallic mine is the tailings after rare earth separation by the Baogang concentrator using a magnetic separation-flotation combined process. The main components are hematite and limonite, followed by bastnaesite, monazite, etc. The niobium minerals are mainly rutile, calcite, and columbite, while the gangue minerals include amphibole, pyroxene, mica, apatite, and quartz. Currently, there are two main research processes for rare earth flotation tailings. One is a reverse flotation (removal of silicate / carbonate minerals) – niobium flotation – iron flotation process. This process uses a combination of sulfuric acid, carboxymethyl cellulose, LH, LJ, oxalic acid, SN, and pine oil reagents for niobium flotation, which can obtain niobium concentrate containing 4.9% niobium and with a recovery rate of 28.25% from rare earth tailings with a Nb2O5 content of 0.2%. The other process is a reverse flotation (removal of silicate / carbonate minerals) – iron flotation – niobium flotation – magnetic separation process. This process uses sulfuric acid, carboxymethyl cellulose, oxalic acid, salicylic acid hydroxamic acid + C for niobium flotation. 5～9 The niobium concentrate obtained using a hydroxamic acid reagent combination was further separated from niobium and iron using strong magnetic separation. Ultimately, a niobium concentrate containing 2.84% niobium and with a recovery rate of 26.42% could be obtained from a feed with an Nb₂O₅ content of 0.126%. A review of niobium ore beneficiation practices both domestically and internationally reveals that foreign niobium ores have simpler compositions and coarser particle sizes, allowing for higher Nb₂O₅ grades and recovery rates after desliming and flotation. In contrast, domestic niobium ores have complex compositions, finer particle sizes, and significant amounts of slime interfere with the beneficiation of fine-grained niobium ore, resulting in lower Nb₂O₅ grades and recovery rates in the niobium concentrate.

[0004] There are many types of flocculants available, mainly divided into inorganic flocculants and polymeric organic flocculants. Common inorganic flocculants include alum, polyaluminum chloride, and polyferric sulfate, while common polymeric organic flocculants include polyacrylamide, sodium polyacrylate, and starch. However, most flocculants lack selectivity in their flocculation of minerals and cannot be used for selective flocculation and desliming of fine-grained niobium ore. Summary of the Invention

[0005] To overcome the problems in the prior art, this invention provides the application of phosphated starch in selective flocculation and desliming of fine-grained niobium ore, which produces a specific selective flocculation effect on niobium ore, removes fine-grained gangue minerals, and achieves artificial growth of fine-grained niobium ore particle size, thus solving the problem of difficult recovery of fine-grained niobium ore.

[0006] To solve the above-mentioned technical problems, the present invention proposes the following technical solution:

[0007] This invention provides the application of phosphorylated starch in selective flocculation and desliming of fine-grained niobium ore, wherein the phosphorylated starch has one or more of the following structural formulas (1) to (3):

[0008]

[0009] In formulas (1) to (3), St is a polysaccharide group of starch, which is a polymer chain composed of multiple six-carbon sugar units linked by glycosidic bonds, and connected to Nb by phosphate ester groups. 5+ A chelation reaction occurs, and the polysaccharide polymer chains produce flocculation, selectively flocculating niobium ore and removing fine-grained gangue minerals.

[0010] In this invention, phosphated starch is used for selective flocculation and desliming of niobium ore. In the phosphated starch, St is a polysaccharide group of starch, with the structure shown in formula (4), possessing a starch glycosyl polymer chain and phosphate ester functional groups. The phosphate ester is used to target the niobium ore. 5+ The chelation reaction and the flocculation effect of polysaccharide polymer chains produce a specific selective flocculation effect on niobium ore, removing fine gangue minerals.

[0011]

[0012] As an optional implementation, in the application provided by the present invention, the niobium ore is at least one of pyrochlore, uranium-thorium pyrochlore, columbite, niobium-manganese ore, yttrium niobite, β-yttrium niobite, yttrium niobite, β-yttrium niobite, yttrium niobite, β-yttrium niobite, neodymium niobite, β-yttrium niobite, neodymium yttrium niobite, calcite, niobium-calcium ore, niobium-iron rutile, and baotou ore.

[0013] As an optional implementation, in the application provided by this invention, the process of selectively flocculating fine-grained niobium ore using phosphorylated starch includes the following steps:

[0014] S1. Adjust the pH of the fine-particle niobium ore slurry to alkaline, then add the dispersant and stir to fully disperse the slurry;

[0015] S2. The phosphoric acid esterified starch is added to the slurry after dispersion treatment, and after being mixed evenly, flocculation and sedimentation are carried out. The overflow is fine gangue minerals, and the sediment is flocculated niobium ore.

[0016] As an optional implementation, in the application provided by the present invention, the concentration of the fine-grained niobium ore slurry is 1% to 20%, and the feed particle size is -10μm, accounting for 100%.

[0017] Preferably, the concentration of fine-grained niobium ore slurry is 1% to 10%.

[0018] In this invention, the concentration of niobium ore slurry is controlled at 1% to 20%, which conforms to the actual industrial production. If the slurry concentration is too low, more desliming cycles are required for the same amount of dry ore, reducing efficiency. If the concentration is too high, gangue will be carried into the sediment, affecting the selective flocculation effect. At the same time, if the feed particle size is too coarse, the minerals will not be fully liberated, and the mass of the mineral particles will be large. Under the action of gravity, they are also prone to settling and cannot be stably dispersed and suspended in the slurry, affecting the selective flocculation effect.

[0019] As an optional implementation, in the application provided by this invention, the amount of phosphoric acid esterified starch added is 10 mg to 100 mg per liter of fine-particle niobium ore slurry. If the amount of flocculant added in this invention is too small, the niobium ore flocculation and sedimentation will be incomplete, resulting in a low niobium ore recovery rate in the sediment; if the amount added is too large, excessive flocculant may cause the already formed niobium mineral flocs to redisperse, resulting in reverse flocculation, which also reduces the effect of selective flocculation and sedimentation.

[0020] Preferably, the amount of phosphorylated starch added is 10-50 mg.

[0021] As an optional implementation, in the application provided by the present invention, the dispersant is at least one of sodium hydroxide, sodium carbonate, sodium hexametaphosphate, water glass, sodium humate, sodium tripolyphosphate, and polyvinylpyrrolidone (PVP).

[0022] The purpose of using dispersants in this invention is to fully disperse the various mineral particles in the slurry and prevent heterogeneous coagulation and agglomeration between different mineral particles, because such coagulation and agglomeration are non-selective and will affect the subsequent selective flocculation effect.

[0023] In this invention, sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate are common pH adjusters. At the same time, the ions they dissociate can be adsorbed on the surface of mineral particles, forming a double electric layer on the surface of solid particles, generating electrostatic repulsion, making it difficult for particles to aggregate, thereby maintaining a dispersed state.

[0024] Preferably, the dispersant is sodium tripolyphosphate.

[0025] In this invention, sodium tripolyphosphate is used as a dispersant, whose molecules contain multiple phosphate groups (PO4). 3- These groups can form hydrogen bonds with water molecules, and their long-chain structure can coat the surface of particles, forming a hydration film that effectively prevents particle aggregation, thus maintaining good dispersion in water. Simultaneously, sodium tripolyphosphate can dissociate into negatively charged ions, which can adsorb onto the surfaces of positively charged or easily polarized particles, preventing particle approach and aggregation through electrostatic repulsion, further enhancing dispersion stability. Furthermore, sodium tripolyphosphate also possesses pH-regulating, complexing, and solubilizing properties; these combined characteristics make it a highly efficient dispersant.

[0026] As an optional implementation, in the application provided by the present invention, the amount of dispersant added is 10 mg to 200 mg per liter of fine-grained niobium ore slurry.

[0027] In this invention, the amount of dispersant added is controlled to be 10mg to 200mg per liter of fine niobium ore slurry. If the amount added is too small, unnecessary particle agglomeration will occur, reducing the selective flocculation effect and separation efficiency. If too much dispersant is added, the already flocculated particles will be redispersed, resulting in a "secondary mudification" phenomenon, which also reduces the flocculation effect.

[0028] Preferably, the amount of dispersant added is 10mg to 50mg.

[0029] As an optional implementation, in the application provided by the present invention, in step S1, the stirring time is 1 min to 20 min, and the stirring speed is 100 rpm to 2000 rpm.

[0030] Preferably, the stirring time is 1 min to 5 min; the stirring speed is 600 rpm to 1000 rpm.

[0031] As an optional implementation, in the application provided by the present invention, in step S1, the pH is adjusted to 8-12.

[0032] In this invention, the pH of the fine-grained niobium ore slurry is controlled at 8-12, resulting in good mineral dispersion performance. This is because under alkaline conditions, the absolute value of the zeta potential on the mineral surface increases, which enhances the electrostatic repulsion between mineral particles and helps stabilize the dispersion of mineral particles. Conversely, under acidic conditions, the electrostatic repulsion between mineral particles decreases, making it easier for mineral particles to precipitate and difficult to achieve selective flocculation and sedimentation.

[0033] Preferably, the pH is adjusted to 8–10.

[0034] As an optional implementation, in the application provided by the present invention, in step S1, the reagent for adjusting pH is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, and potassium carbonate solution.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] This invention addresses the technical bottlenecks of difficult recovery and utilization of fine-grained niobium ore and the lack of selectivity of existing flocculants for niobium mineral flocculation. It innovatively applies phosphate-esterified starch to the selective flocculation and desliming of niobium ore. Phosphate-esterified starch possesses the glycosyl polymer chain of starch and phosphate ester functional groups. The O atoms on the phosphate ester functional groups have abundant lone pairs of electrons, Nb 5+ With an empty 4d orbital, niobium readily forms a four-membered ring chelate with the niobium, exhibiting high chelation selectivity and thus enabling selective adsorption. The phosphate ester is used for Nb... 5+ The chelation reaction and flocculation effect of polysaccharide polymer chains produce a specific selective flocculation effect on niobium ore, removing fine-grained gangue minerals and artificially increasing the particle size of fine-grained niobium ore, which is expected to solve the problem of difficult recovery of fine-grained niobium ore. In this invention, after selective flocculation, some fine mud is removed. In order to increase the niobium content in the sediment, subsequent flotation is required. If the niobium ore particle size is too small, the flotation reagents are difficult to apply, which not only increases the amount of flotation reagents used, but also worsens the flotation index. Therefore, the particle size of fine-grained niobium ore is increased after selective flocculation, which is beneficial to the subsequent flotation to improve the niobium grade. In addition, phosphated starch raw materials are widely available, have good biodegradability, and are simple to prepare, which has great industrial application value. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are derived from some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0038] Figure 1 This is the infrared spectrum of the phosphorylated starch in this invention;

[0039] Figure 2 This is a flowchart illustrating the selective flocculation and desliming process for fine-grained niobium ore according to the present invention. Detailed Implementation

[0040] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0042] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0043] Example 1

[0044] Selective flocculation and desliming test of phosphorylated starch on gravity separation of raw ore from Bayan Obo West Mine, the steps are as follows: Figure 2 As shown:

[0045] Weigh 10g of gravity concentrate with a particle size of -10μm (100% concentration; niobium ore mainly consists of columbite, followed by pyrochlore and calcite; gangue minerals mainly include feldspar, biotite-phlogopite, calcite, dolomite-ferrodolithite, quartz, apatite, pyroxene-amphibole, etc.; Nb₂O₅ content 0.37%) and mix it with water. Stir the slurry at 400rpm for 3 minutes using an electric stirrer to obtain a slurry concentration of 10%. Adjust the pH of the slurry to 10 with sodium hydroxide solution and stir at 800rpm for 3 minutes. After being transferred to a 100 ml settling tube, sodium tripolyphosphate at a concentration of 50 mg / L was added. After inverting the tube 20 times, phosphated rice starch (2.1% degree of substitution) at a concentration of 30 mg / L was added. The volume was then adjusted to the mark with distilled water. The tube was inverted 20 times again and allowed to stand for 8 minutes. The upper slurry was then siphoned off, which removed fine mud with a yield of 35%, an Nb2O5 grade of 0.13%, and an Nb2O5 loss rate of 12.30% in one go. The lower sediment had an Nb2O5 grade of 0.50%.

[0046] Comparative Example 1

[0047] Niobium ore flocculation and desliming tests were conducted using commonly used anionic polyacrylamide and rice starch, following the same process. The polyacrylamide dosage was 10 mg / L, and the starch dosage was 30 mg / L, with other conditions identical to those in Case Study 1. Using polyacrylamide as a flocculant, the slurry settled rapidly, the supernatant became clear, and there was no selective flocculation effect. Using starch as a flocculant, it could remove fine mud with a yield of 15%, Nb₂O₅ grade of 0.23%, and Nb₂O₅ loss rate of 9.32% in a single pass, with the settled sand having an Nb₂O₅ grade of 0.39%. The desliming effect was not as good as that of phosphoric acid esterified starch.

[0048] In summary, the fine mud yield in Example 1 was 35%, and the Nb2O5 grade was 0.13%, while the fine mud yield in Comparative Example 1 was only 15%, and the Nb2O5 grade was 0.23%. Although Example 1 had a slightly higher loss rate, it had a higher fine mud removal yield, a lower Nb2O5 grade in the fine mud, and a higher Nb2O5 grade in the sediment. Considering all factors, Example 1 had higher selectivity and better desliming effect.

[0049] Example 2

[0050] Selective flocculation and desliming test of phosphated starch on niobium ore in the main eastern mine of Bayan Obo, the steps are as follows: Figure 2 As shown:

[0051] Weigh 5g of rare earth tailings with a particle size of -10μm (100% rare earth content; niobium ore mainly consists of calcite, followed by pyrochlore, columbite, and columbite-rutile; gangue minerals mainly include fluorite, dolomite-ferrodolithite, pyroxene-amphibolite, magnetite-hematite, quartz, apatite, bastnaesite, biotite-phlogopite, calcite, feldspar, etc.; Nb₂O₅ content 0.18%) and mix with water. Stir the slurry for 3 minutes at 400 rpm using an electric stirrer to prepare a 5% concentration slurry. Adjust the pH of the slurry to 10 using potassium hydroxide solution. After stirring at rpm for 3 minutes, the mixture was transferred to a 100 ml settling tube. Sodium tripolyphosphate at a concentration of 30 mg / L was added, and the mixture was inverted 20 times. Phosphate-esterified corn starch (1.7% degree of substitution) at a concentration of 20 mg / L was then added. The mixture was brought to the mark with distilled water, and the mixture was inverted 20 times again. After standing for 9 minutes, the upper slurry was siphoned off. This process can remove fine mud with a yield of 30%, an Nb2O5 grade of 0.068%, and an Nb2O5 loss rate of 11.30% in one step, resulting in a settled sand with an Nb2O5 grade of 0.23%.

[0052] Comparative Example 2

[0053] Niobium ore flocculation and desliming tests were conducted using commonly used amphoteric polyacrylamide and corn starch, following the same process. The dosage of polyacrylamide was 10 mg / L, and the dosage of starch was 20 mg / L, with other conditions identical to those in Case 2. Using polyacrylamide as a flocculant, the slurry settled rapidly, the solution became clear, and there was no selective flocculation effect. Using starch as a flocculant, it could remove fine mud with a yield of 20%, an Nb₂O₅ grade of 0.25%, and an Nb₂O₅ loss rate of 13.51% in a single pass, with the settled sand having an Nb₂O₅ grade of 0.19%. The desliming effect was not as good as that of phosphoric acid esterified starch.

[0054] Example 3

[0055] Selective flocculation and desliming test of phosphorylated starch on Yichun tantalum-niobium ore, the steps are as follows: Figure 2 As shown:

[0056] Weigh 7.5g of gravity separation tailings (niobium ore mainly composed of manganese-rich niobite, followed by fine-grained ore, with quartz and feldspar as the main gangue minerals; Nb₂O₅ content 0.25%) with 100% particle size of -10μm and mix with water. Stir the slurry at 400rpm for 3min using an electric stirrer to achieve a slurry concentration of 7.5%. Adjust the pH of the slurry to 10 with sodium hydroxide solution and stir at 600rpm for 3min. Then transfer the mixture to a 100mL volumetric flask and add sodium tripolyphosphate at a concentration of 50mg / L. Invert the flask 20 times. After the slurry is fully dispersed, phosphated potato starch (2.5% degree of substitution) is added at a concentration of 20 mg / L. The volume is then adjusted to the mark with distilled water. The mixture is then inverted 20 times and allowed to stand for 9 minutes. The upper slurry is then siphoned off, which removes fine mud with a yield of 35%, an Nb2O5 grade of 0.05%, and an Nb2O5 loss rate of 7.00% in one step. The resulting sediment has an Nb2O5 grade of 0.36%.

[0057] Comparative Example 3

[0058] Flocculation and desliming tests were conducted using commonly used sodium polyacrylate and phosphorylated arabinoxylan (pentose sugar) according to the same process. The dosage of sodium polyacrylate was 10 mg / L, and the dosage of phosphorylated arabinoxylan was 20 mg / L. Other conditions were the same as in Case 3. When sodium polyacrylate was used as a flocculant, the slurry settled rapidly, the solution became clear, and there was no selective flocculation effect. When phosphorylated arabinoxylan was used as a flocculant, it could remove fine mud with a yield of 39%, an Nb2O5 grade of 0.15%, and an Nb2O5 loss rate of 23.40% in one pass. The Nb2O5 grade of the settled sand was 0.31%, and the selective desliming effect was not as good as that of phosphorylated starch.

[0059] In summary, although phosphorylated pentose has a certain selectivity for niobium ore (the Nb2O5 grade in the overflow is lower than that in the sediment), due to the small molecular weight of phosphorylated arabinoxylan, the flocculation and sedimentation effect is poor, and the overflow yield is too large (far greater than the overflow yield in Comparative Example 1 and Comparative Example 2), resulting in a large loss of Nb2O5 in the overflow.

[0060] The phosphoric acid esterified starches used in Examples 1-3 of this invention are phosphoric acid esterified rice starch, phosphoric acid esterified corn starch, and phosphoric acid esterified potato starch, respectively. Since the reaction between phosphoric acid and starch is a very complex process, it often yields a mixture of three structures: substances with one hydroxyl group, two hydroxyl groups, and three hydroxyl groups bonded to starch. Therefore, the phosphoric acid esterified rice starch used in this application is a mixture of phosphoric acid esterified corn starch containing one, two, and three hydroxyl groups. Similarly, the phosphoric acid esterified corn starch and phosphoric acid esterified potato starch are also...

[0061] Figure 1 The infrared spectra of phosphorylated starch in embodiments 1 to 3 of this invention show that phosphate groups were successfully grafted onto the carbon chain of the starch polymer. The selective flocculant used in the patent is true phosphorylated starch. Because the functional groups are the same, the infrared spectra of different phosphorylated starches are the same.

[0062] This invention uses phosphoric acid esterified starch as a selective flocculant for niobium minerals. Through comparative implementation cases, it was found that compared with traditional flocculants, phosphoric acid esterified starch can selectively flocculate fine-grained niobium ore, remove ore slime and enrich niobium, which helps to solve the problem of the difficulty in recycling fine-grained niobium ore and has extremely high market application prospects.

[0063] This invention discloses the application of phosphated starch in selective flocculation and desliming of fine-grained niobium ore. The phosphated starch molecule contains both polysaccharide polymer chains and phosphate groups. The phosphate groups chelate with niobium ions exposed on the surface of niobium minerals, allowing the phosphated starch to selectively adsorb onto the surface of niobium minerals. The polysaccharide polymer chains play a bridging and sweeping role, giving it a strong selective flocculation effect on niobium-containing minerals such as pyrochlore, columbite, and calcite in fine-grained niobium ore. This selective flocculation and desliming method can significantly remove fine-grained gangue slime and improve the Nb2O5 grade, which is of great significance for the efficient recovery and utilization of fine-grained niobium ore.

[0064] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. However, it should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. The application of phosphated starch in selective flocculation and desliming of fine-grained niobium ore, characterized in that, The phosphorylated starch has one or more of the following structural formulas (1) to (3): In formulas (1) to (3), St is a polysaccharide group of starch, which is a polymer chain composed of multiple six-carbon sugar units linked by glycosidic bonds, and connected to Nb by phosphate ester groups. 5+ A chelation reaction occurs, and the polysaccharide polymer chains produce flocculation, which selectively flocculates niobium ore and removes fine gangue minerals. The process for selectively flocculating fine-grained niobium ore using the above-mentioned phosphorylated starch includes the following steps: S1. Adjust the pH of the fine-particle niobium ore slurry to alkaline, then add a dispersant and stir to fully disperse the slurry; the concentration of the fine-particle niobium ore slurry is 1%–20%, and the feed particle size is -10 μm, accounting for 100%; S2. The phosphoric acid esterified starch is added to the slurry after dispersion treatment, and after being mixed evenly, flocculation and sedimentation are carried out. The overflow is fine gangue minerals, and the sediment is flocculated niobium ore. The amount of phosphoric acid esterified starch added is 10 mg to 100 mg per liter of fine niobium ore slurry.

2. The application of phosphated starch according to claim 1 in the selective flocculation and desliming of fine-grained niobium ore, characterized in that, The niobium ore is at least one of the following: pyrochlore, uranium-thorium pyrochlore, columbite, niobium-manganese ore, yttrium niobium ore, β-yttrium niobium ore, yttrium niobium ore, β-yttrium niobium ore, yttrium niobium ore, β-yttrium niobium ore, neodymium niobium ore, calcite, niobium-calcium ore, niobium-iron rutile, and baotou ore.

3. The application of phosphorylated starch according to claim 1 in the selective flocculation and desliming of fine-grained niobium ore, characterized in that, The dispersant is at least one of sodium hydroxide, sodium carbonate, sodium hexametaphosphate, water glass, sodium humate, sodium tripolyphosphate, and polyvinylpyrrolidone.

4. The application of phosphorylated starch according to claim 1 in the selective flocculation and desliming of fine-grained niobium ore, characterized in that, The amount of dispersant added is 10 mg to 200 mg per liter of fine-grained niobium ore slurry.

5. The application of phosphated starch according to claim 1 in the selective flocculation and desliming of fine-grained niobium ore, characterized in that, In step S1, the stirring time is 1 min to 20 min, and the stirring speed is 100 rpm to 2000 rpm.

6. The application of phosphoric acid esterified starch according to claim 1 in the selective flocculation and desliming of fine-grained niobium ore, characterized in that, In step S1, the pH is adjusted to 8-12.

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