A method for ore phase reconstruction and efficient separation of tailings of Baiyunebo

Abstract

The present application relates to the technical field of mineral processing, and discloses a method for mineral phase reconstruction and efficient separation of Baiyunebo tailings, which comprises the following steps: heating raw ore and introducing hydrogen-based gas to perform hydrogen-based pre-reduction, so as to obtain a reduction product; adding a modification agent to the reduction product and performing high-temperature melting modification, so as to obtain molten slag and molten iron after heat preservation, separate the molten iron, and obtain modified slag; cooling the modified slag under a preset cooling rate, heat preservation, and water quenching treatment, so as to obtain a slag sample; crushing and grinding the slag sample, and performing flotation treatment, so as to obtain flotation tailings containing niobium and rare earth and perovskite containing niobium and rare earth. The present application uses clean and environmentally friendly hydrogen as a reducing agent for pre-reduction, which has great environmental benefits. The high-temperature melting state at the end of the melting modification provides favorable conditions for mineral phase reconstruction. The mineral phase reconstruction process does not need to roast or remelt the treatment object, avoids high energy consumption caused by secondary heating, shortens the process, and saves energy consumption.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and in particular to a method for facies reconstruction and efficient separation of Bayan Obo tailings. Background Technology

[0002] In the Bayan Obo tailings, niobium, rare earth elements, iron, and titanium coexist. Due to the low grade, fine particle size, and intergrowth of mineral phases, the selectivity of valuable components is small, making separation and extraction difficult. For example, Baogang Group (patent CN115090411A) achieved niobium ore beneficiation requirements through a four-stage flotation process with sequential reagent addition, increasing the niobium concentrate grade to over 4%. However, the iron content in the niobium concentrate remained high. Beijing University of Science and Technology and Northeastern University, addressing the high iron content in the tailings, employed a combination of selective reduction and magnetic separation, achieving iron reduction extraction and preliminary enrichment of rare earth elements and niobium in the tailings.

[0003] It should be noted that valuable elements in the magnetic separation tailings are still dispersed in mineral phases such as calcite ((Ce,Nd)(Ti.Nb), pyrochlore ((Ca,Na,Ce)2(Nb,Ti,Ta)2O6(F,OH)), and niobium-iron rutile ((Fe,Ti,Nb)O2). The rare earth and niobium grades in the slag obtained from the "selective pre-reduction-electric furnace smelting-electric furnace smelting of niobium-titanium ferroalloy" process are far below the levels of industrial-grade rare earth and niobium concentrates, thus greatly limiting the quality and application areas of subsequent products. The poor, fine, complex, and dispersed mineral phases have consistently hampered the extraction and utilization of rare earth elements and niobium. Furthermore, in selective pre-reduction processes, carbonaceous reducing agents are often used to reduce metallic elements. However, carbon readily reacts with oxides of elements such as niobium and titanium in the slag at high temperatures, forming niobium carbides. This process significantly increases the viscosity of the slag, accompanied by severe foaming, making slag-iron separation extremely difficult and potentially leading to furnace charge splashing accidents. Simultaneously, the carbothermic reduction process generates a large amount of carbon dioxide emissions. Summary of the Invention

[0004] (a) Technical problems to be solved

[0005] Given that the grades of rare earth and niobium in the slag obtained by the "selective pre-reduction-electric furnace melting-electric furnace smelting of niobium-titanium-iron alloy" process in the existing technology are far from reaching the level of industrial-grade rare earth concentrate and niobium concentrate, this greatly limits the technical problems of the quality of subsequent products and their application fields.

[0006] (II) Technical Solution

[0007] Therefore, this invention provides a method for mineral phase reconstruction and efficient separation of Bayan Obo tailings, including:

[0008] Step 1: After heating the raw ore to a first preset temperature, hydrogen is introduced for hydrogen pre-reduction. After a first preset reduction time, the reduction product is obtained.

[0009] Step 2: Add a modifier to the reduction product, heat it to a second preset temperature for melting and modification, hold it at the temperature for a second preset time to obtain slag and molten iron, separate the molten iron to obtain modified slag;

[0010] Step 3: Cool the modified slag in the high-temperature molten state obtained in Step 2 to the third preset temperature under a preset cooling rate, hold it at the temperature for the third preset time, and then perform water quenching treatment to obtain a slag sample.

[0011] Step 4: After crushing and grinding the slag sample obtained in Step 3, flotation treatment is carried out to obtain flotation perovskite containing niobium and rare earth elements and flotation tailings.

[0012] Further, in step 1, the raw material ore composition, based on a total mass percentage of 100%, includes: T.Fe: 0-50%, Nb2O5: 1-10%, TiO2: 1-20%, REO: 1-25%, SiO2: 5-40%, CaO: 2-20%, F: 2-20%, with the balance being unavoidable impurities.

[0013] Furthermore, in step 1, the raw ore is ground to a particle size of less than or equal to 200 mesh, accounting for 80-90 wt% of the total ore.

[0014] Further, in step 1, the raw ore is placed in a high-temperature furnace for heating. The high-temperature furnace includes at least one of a plasma melting furnace, a high-temperature tubular drip furnace, a hydrogen-based vertical shaft furnace, a blast furnace, a rotary kiln, and a fluidized bed.

[0015] Furthermore, in step 1, the first preset temperature is 750-1200℃, the first preset time for hydrogen pre-reduction is 30-150min, and the flow rate of hydrogen is 300-1500mL / min.

[0016] Further, in step 1, the hydrogen-based component includes one or more of hydrogen, coke oven gas, cracked natural gas, and reformed coal gas.

[0017] Furthermore, in step 2, the modifier includes at least one of lime, dolomite, limestone, quartz sand, and quartz.

[0018] Furthermore, in step 2, the second preset temperature is 1300-1600℃, and the second preset time is 5-60min.

[0019] Furthermore, in step 3, the preset cooling rate is 0.1-5℃ / min, the third preset temperature is 1300-1100℃, and the third preset time is greater than or equal to 30min.

[0020] Furthermore, in the flotation process, the grinding slag sample is reduced to a particle size of 200-300 mesh, the collector is one of oleic acid, hydroxamic acid, dodecylamine dimethylphosphonic acid, or octyl isohydroxamic acid, the inhibitor is one of sodium fluorosilicate or water glass, and the modifier is one of sulfuric acid or sodium hydroxide.

[0021] (III) Beneficial Effects

[0022] The beneficial effects of this invention are as follows: This invention provides a method for phase reconstruction and efficient separation of Bayan Obo tailings, comprising: heating the raw ore to a first preset temperature and then introducing hydrogen for hydrogen-based pre-reduction to obtain a reduction product; adding a modifier to the reduction product and heating it to a second preset temperature for melting modification, holding it at the temperature for a second preset time to obtain slag and molten iron, separating the molten iron to obtain modified slag; cooling the obtained high-temperature molten modified slag to a third preset temperature under a preset cooling rate, holding it at the temperature for a third preset time, and then water quenching it to obtain a slag sample; crushing and grinding the obtained slag sample and then performing flotation treatment to obtain flotation perovskite containing niobium and rare earth elements and flotation tailings.

[0023] This application utilizes hydrogen as a clean and environmentally friendly emerging strategic energy source, which can effectively avoid the formation of carbides and foaming phenomena. Therefore, this method uses hydrogen as a reducing agent for selective pre-reduction. In the melting and upgrading stage, a modifier is added to melt-up and upgrade the Bayan Obo tailings to improve the viscosity and fluidity of the slag and promote the separation of slag and iron. Due to the structure of ABO3-type perovskite, Ca... 2+ Occupying site A, Ti 4+ Occupying the B site, when niobium and rare earth elements enter the perovskite, Nb 5+ It will occupy part of Ti 4+ Site, rare earth elements occupy part of Ca 2+ Due to its location, perovskite can accommodate varying amounts of niobium and rare earth oxides. Therefore, by controlling the temperature using the high-temperature molten state of the slag at the end of the melting and refining process, directional crystallization of niobium and rare earth elements in the tailings can be achieved, resulting in a single, coarse-grained perovskite containing niobium and rare earth elements. Finally, through flotation, the grade of niobium and rare earth elements is increased to more than four times that of the original ore. This mineral phase reconstruction method eliminates the need for roasting or remelting the treated material, thus avoiding the high energy consumption caused by secondary heating. Attached Figure Description

[0024] Figure 1 This is a schematic flowchart of a method for mineral facies reconstruction and efficient separation of Bayan Obo tailings mentioned in this application;

[0025] Figure 2 This is a process flow diagram of a method for mineral phase reconstruction and efficient separation of Bayan Obo tailings mentioned in this application. Detailed Implementation

[0026] To better explain and facilitate understanding of the present invention, the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1-5” is disclosed, the described range should be interpreted as including ranges “1-4”, “1-3”, “1-2”, “1-2 and 4-5”, “1-3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0028] In these embodiments, unless otherwise specified, parts and percentages are all by mass. A “part by mass” refers to a basic unit of measurement representing the mass ratio of multiple components. One part can represent any unit mass, such as 1 g or 3.527 g. If we say that component A has a parts by mass and component B has b parts by mass, it means the mass ratio of component A to component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (K is any number representing a multiplier). It should not be misunderstood that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 100 parts. “And / or” is used to indicate that one or both of the described situations may occur; for example, A and / or B includes (A and B) and (A or B).

[0029] refer to Figure 1 and Figure 2 This application mentions a method for mineral facies reconstruction and efficient separation of Bayan Obo tailings, including:

[0030] Step 1: After heating the raw ore to a first preset temperature, hydrogen is introduced for hydrogen pre-reduction. After a first preset time, the reduction product is obtained.

[0031] This application selects Bayan Obo tailings as the raw material. Based on a total mass percentage of 100%, the raw material comprises: T.Fe: 0-50%, Nb₂O₅: 1-10%, TiO₂: 1-20%, REO: 1-25%, SiO₂: 5-40%, CaO: 2-20%, F: 2-20%, with the balance being unavoidable impurities. By clearly defining the content ranges of key components such as T.Fe (Total Iron), Nb₂O₅, TiO₂, and REO (Rare Earth Oxides) in the raw material, it is beneficial to select appropriate reduction conditions and subsequent processing steps. For example, for high-content niobium and rare earth elements, conditions such as reduction temperature, reduction time, and cooling rate can be optimized to improve their recovery rate.

[0032] It should be noted that heating the raw ore to a certain temperature can increase the reactivity of the minerals. The reduction reaction can be carried out using one or more of hydrogen, coke oven gas, pyrolyzed natural gas, and reformed coal gas. Multiple hydrogen-based sources, including hydrogen, coke oven gas, pyrolyzed natural gas, and reformed coal gas, allow for the selection of the most economical and environmentally friendly reducing agent based on actual conditions.

[0033] In this technical solution, in step 1, the raw ore is ground to a particle size of 200 mesh or less, accounting for 80-90 wt% of the total ore. Grinding the raw ore to this size increases the specific surface area of ​​the minerals, improving the contact area with the hydrogen-based reducing agent, thereby accelerating the reduction reaction, shortening the reduction time, and increasing production efficiency. Fine-grained raw ore is more likely to achieve uniform reaction during heating and reduction, reducing unreacted areas and improving the quality and consistency of the reduction product. Furthermore, fine-grained ore is easier to mix thoroughly with the modifier and flotation reagents in subsequent high-temperature melting and flotation steps, improving the processing effect.

[0034] In this technical solution, in step 1, the raw ore is placed in a high-temperature furnace for heating. The high-temperature furnace includes at least one of the following: plasma melting furnace, high-temperature tubular drip furnace, hydrogen-based vertical shaft furnace, blast furnace, rotary kiln, and fluidized bed. This application can select a suitable high-temperature furnace based on actual production conditions and needs. Plasma melting furnaces are characterized by high temperature and high energy density, making them suitable for processing refractory minerals; hydrogen-based vertical shaft furnaces are suitable for large-scale continuous production; rotary kilns and fluidized beds have good heat and mass transfer performance, making them suitable for specific reduction reactions. For raw ores with different compositions and properties, the most suitable high-temperature furnace can be selected for heating and reduction, improving the adaptability and reliability of the process.

[0035] In this technical solution, in step 1, the first preset temperature is 750-1200℃, the reduction time for hydrogen pre-reduction is the first preset time, which is 30-150 min, and the flow rate of hydrogen is 300-1500 mL / min.

[0036] In this application, the first preset temperature is the reduction temperature, ranging from 750 to 1200°C. Within this temperature range, the hydrogen-based reducing agent exhibits high activity and can effectively reduce metal oxides to metals or lower-valence oxides. A reduction time of 0-150 min ensures the reaction proceeds fully, improving the quality of the reduction product. A hydrogen flow rate of 300-1500 mL / min guarantees the smooth progress of the reduction reaction while avoiding hydrogen waste and safety risks. By controlling the hydrogen flow rate, the reduction reaction rate can be adjusted, coordinating with the reduction time and temperature to achieve efficient production.

[0037] Step 2: Add a modifier to the reduction product, heat it to a second preset temperature for melting and modification, hold it at the temperature for a second preset time to obtain slag and molten iron, separate the molten iron to obtain modified slag;

[0038] In this technical solution, in step 2, the modifier includes at least one of lime, dolomite, limestone, quartz sand, and quartz. Adding the modifier can adjust the physicochemical properties of the slag, making it more favorable for subsequent separation and processing.

[0039] In this technical solution, in step 2, the melting temperature of the high-temperature molten modification, i.e., the second preset temperature, is 1300-1600℃, and the second preset time is 5-60 minutes. During the 5-60 minute holding time, the reaction can proceed more fully, allowing for better separation of the slag and molten iron.

[0040] This application utilizes a modifier to reduce the viscosity of molten slag, making it easier to separate molten iron and improving iron recovery rate.

[0041] Step 3: Cool the modified slag in the high-temperature molten state obtained in Step 2 to a third preset temperature under a preset cooling rate, hold it at that temperature for a third preset time, and then perform water quenching treatment to obtain a slag sample.

[0042] In this technical solution, in step 3, the preset cooling rate is 0.1-5℃ / min, the third preset temperature is 1300-1100℃, and the third preset time is greater than or equal to 30min.

[0043] This application enables minerals in molten slag to crystallize and undergo phase transformation under specific temperature conditions by controlling the cooling rate, forming a specific mineral phase structure. Holding the temperature for 30 minutes or more allows these crystallization and phase transformation processes to be more complete. Specifically, this application induces crystallization in molten slag at a certain cooling rate, during which different phases precipitate. Rapid cooling with water quenching preserves the precipitated phases. For example, slag molten at 1600°C is cooled to 1100°C at a cooling rate of 1°C / min, resulting in perovskite precipitation. Rapid water quenching fixes the perovskite mineral phase at 1100°C.

[0044] Step 4: After crushing and grinding the slag sample obtained in Step 3, flotation treatment is carried out to obtain flotation perovskite containing niobium and rare earth elements and flotation tailings.

[0045] In this technical solution, during the flotation process, the grinding slag sample is reduced to a particle size of 200-300 mesh. The collector is one of oleic acid, hydroxamic acid, dodecylamine dimethylphosphonic acid, or octyl isohydroxamic acid. The inhibitor is one of sodium fluorosilicate or water glass. The modifier is one of sulfuric acid or sodium hydroxide. The foaming agent is No. 2 oil.

[0046] Crushing and grinding can refine the slag sample, increase the specific surface area of ​​the minerals, and improve flotation efficiency. This application obtains high-grade niobium- and rare-earth-containing perovskite through flotation, providing high-quality raw materials for further processing and utilization. It effectively separates niobium- and rare-earth-containing minerals, improving the recovery rate of niobium and rare-earth elements.

[0047] This invention proposes a method for phase reconstruction and efficient separation of Bayan Obo tailings. This method utilizes hydrogen as a clean and environmentally friendly emerging strategic energy source, effectively avoiding carbide formation and foaming phenomena. Therefore, this method uses hydrogen as a reducing agent for selective pre-reduction. In the melting and upgrading stage, a modifier is added to melt and upgrade the Bayan Obo tailings to improve the viscosity and fluidity of the slag, promoting the separation of slag and iron. Simultaneously, temperature control is achieved by utilizing the high-temperature melting state of the slag at the end of the melting and upgrading process, enabling the directional crystallization of niobium and rare earth elements in the tailings to obtain cerium-niobium perovskite. Finally, through flotation, the grade of niobium and rare earth elements is increased to more than four times that of the original ore. This phase reconstruction method eliminates the need for roasting or remelting the treated material, thus avoiding the high energy consumption caused by secondary heating.

[0048] This invention uses clean and environmentally friendly hydrogen-based materials as a reducing agent for pre-reduction, avoiding the generation of carbides and foaming, and achieving significant CO2 emission reduction during the reduction process, resulting in substantial environmental benefits. While successfully recovering rare metals, it also achieves efficient iron recovery. The high-temperature molten state at the end of the smelting and tempering process provides favorable conditions for mineral phase reconstruction. This mineral phase reconstruction process eliminates the need for roasting or remelting the treated material, avoiding the high energy consumption caused by secondary heating, shortening the process, and saving energy. Utilizing the easy flotation characteristic of perovskite-type mineral phases, a physical beneficiation (flotation) method is used to obtain high-niobium-grade perovskite-type mineral phases that can be used to prepare high-value-added materials such as niobium-titanium alloys and niobium-titanium composite ceramic materials, effectively recovering rare metal resources and resulting in significant economic benefits.

[0049] To better understand the technical solutions, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present invention can be understood more clearly and thoroughly, and that the scope of the present invention can be fully conveyed to those skilled in the art.

[0050] Example 1

[0051] Step 1: Place the Bayan Obo tailings in a hydrogen-based vertical furnace, heat it to 1000℃, and then introduce hydrogen gas and keep it at that temperature for 90 minutes for hydrogen pre-reduction. The composition of the Bayan Obo tailings is T.Fe 35%, Nb2O5 2%, TiO2 7%, REO 10%, SiO2 35%, CaO 6%, and F 5%.

[0052] Step 2: Add the modifier CaO to the reduction product from Step 1, adjust the basicity to 0.5, place it in a crucible and heat it to 1500℃ to fully melt the material, keep it at that temperature for 30 minutes to completely separate the slag from the metal, pour out the molten iron, and obtain the modified slag.

[0053] Step 3: Cool the modified slag in the high-temperature molten state in Step 2 to 1300℃ at a cooling rate of 1℃ / min, hold it at that temperature for 4 hours, and then perform water quenching treatment.

[0054] Step 4: After crushing and grinding the slag sample obtained in Step 3, perform flotation treatment, adjust the pH value to 6.0, and use 500g / t of hydroxamic acid, 100g / t of water glass, and 60g / t of No. 2 oil.

[0055] Analysis revealed that the Nb2O5 content was 14%, CeO2 content was 45%, TiO2 content was 29%, and the remainder was impurities.

[0056] Example 2

[0057] Step 1: Place the Bayan Obo tailings in a hydrogen-based vertical furnace, heat it to 1100℃, and then introduce hydrogen gas and keep it at that temperature for 150 minutes for hydrogen reduction. The composition of the Bayan Obo tailings is T.Fe 45%, Nb2O5 1%, TiO2 6%, REO 15%, SiO2 28%, CaO 2%, and F 3%.

[0058] Step 2: Add the modifier CaO to the reduction product from Step 1, adjust the basicity to 1.0, place it in a crucible and heat it to 1600℃ to fully melt the material, keep it at this temperature for 60 minutes to completely separate the slag from the metal, pour out the molten iron, and obtain the modified slag.

[0059] Step 3: Cool the modified slag in the high-temperature molten state in Step 2 to 1100℃ at a cooling rate of 5℃ / min, hold it at that temperature for 10 hours, and then quench it with water.

[0060] Step 4: After crushing and grinding the slag sample obtained in Step 3, perform flotation treatment, adjust the pH value to 10.5, and use 600g / t of oleic acid, 150g / t of water glass, and 50g / t of No. 2 oil.

[0061] Analysis revealed that the Nb2O5 content was 13%, CeO2 content was 46%, TiO2 content was 35%, and the remainder was impurities.

[0062] Example 3

[0063] Step 1: Place the Bayan Obo tailings in a fluidized bed, heat it to 1100℃, and then introduce hydrogen gas to maintain the temperature for 120 minutes for hydrogen reduction. The composition of the Bayan Obo tailings is T.Fe 25%, Nb2O5 5%, TiO2 12%, REO 22%, SiO2 31%, CaO 4%, and F 1%.

[0064] Step 2: Add the modifier CaO to the reduction product from Step 1, adjust the basicity to 1.5, place it in a crucible, and heat it to 1600℃ under the protection of inert gas to fully melt the material. Hold the temperature for 60 minutes to completely separate the slag from the metal.

[0065] Step 3: Cool the material in the high-temperature molten state in Step 2 to 1100℃ at a cooling rate of 3℃ / min, hold it at that temperature for 16 hours, and then quench it with water.

[0066] Step 4: After crushing and grinding the slag sample obtained in Step 3, perform flotation treatment, adjust the pH value to 10.5, and use 200g / t of octylhydroxamic acid, 100g / t of water glass, and 70g / t of No. 2 oil.

[0067] Analysis revealed that the Nb2O5 content was 17%, CeO2 content was 43%, TiO2 content was 37%, and the remainder was impurities.

[0068] The basic principles, main features, and advantages of the present invention have been described above. However, the above description is only a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other embodiments derived by those skilled in the art without departing from the technical solution of the present invention should be covered within the patent scope of the present invention.

[0069] In the description of this invention, each embodiment focuses on its differences from other embodiments, and similar or identical parts between embodiments can be referred to interchangeably. As the apparatus disclosed in the embodiments corresponds to the methods disclosed in the embodiments, the description is relatively simple, and relevant parts can be referred to the method section.

[0070] In the description of this invention, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In the description of this invention, "a plurality of" means two or more, unless otherwise expressly specified. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0071] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that they are in indirect contact through an intermediate medium. Furthermore, "above," "over," or "on top" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," or "beneath" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0072] In the description of this specification, the terms "one embodiment," "some embodiments," "embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for reconstructing the mineral phase of a Baiyunebo tailing and efficiently sorting it, characterized in that, The method comprises the following steps: Step 1: heating the raw ore to a first preset temperature and then introducing a hydrogen-based gas to perform hydrogen-based pre-reduction, and obtaining a reduction product after a first preset reduction time; Step 2: adding a modifying agent to the reduction product and heating to a second preset temperature to perform melting modification, and obtaining molten slag and molten iron after a second preset holding time, separating the molten iron to obtain modified slag; Step 3: cooling the modified slag in a high-temperature molten state obtained in step 2 to a third preset temperature at a preset cooling rate, holding for a third preset time, and performing water quenching treatment to obtain a slag sample; Step 4: crushing and grinding the slag sample obtained in step 3, and then performing flotation treatment to obtain flotation ilmenite containing niobium and rare earth and flotation tailings; In step 1, the components of the raw ore, with the sum of mass percentages being 100%, include: T.Fe: 0-50%, Nb2O5: 1-10%, TiO2: 1-20%, REO: 1-25%, SiO2: 5-40%, CaO: 2-20%, F: 2-20%, and the balance being inevitable impurities; In step 1, the first preset temperature is 750-1200℃, the first preset time of hydrogen-based pre-reduction is 30-150min, and the flow rate of hydrogen-based gas is 300-1500mL / min; In step 2, the modifying agent includes at least one of lime, dolomite, limestone, quartz sand, and quartz stone; In step 2, the second preset temperature is 1300-1600℃, and the second preset time is 5-60min.

2. The method according to claim 1, wherein in step 1, the raw ore is ground to a particle size of 80-90wt% of the total ore amount being less than or equal to 200 mesh.

3. The method according to claim 1, wherein in step 1, the raw ore is heated in a high-temperature furnace, and the high-temperature furnace includes at least one of a plasma smelting furnace, a high-temperature tube type dropping furnace, a hydrogen-based shaft furnace, a blast furnace, a rotary kiln, and a fluidized bed.

4. The method according to claim 1, wherein in step 1, the hydrogen-based gas includes one or more of hydrogen, coke oven gas, cracked natural gas, and coal gas reforming gas.

5. The method according to claim 1, wherein in step 3, the preset cooling rate is 0.1-5℃ / min, the third preset temperature is 1300-1100℃, and the third preset time is greater than or equal to 30min.

6. The method according to claim 1, wherein in the flotation treatment, the slag sample is ground to a particle size of 200-300 mesh, the collector is one of oleic acid, hydroxamic acid, dodecylamine dimethyl phosphonic acid, and octyl isoxazoline acid, the depressant is one of sodium fluorosilicate and water glass, and the regulator is one of sulfuric acid and sodium hydroxide. ​ ​ ​ ​ ​

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