Ore dressing method for obtaining niobium concentrate by extraordinary enrichment

Abstract

The invention discloses a beneficiation method for obtaining niobium concentrate through extraordinary enrichment. The raw ore is ground, the ground product is subjected to magnetic separation, the weakly magnetic minerals after magnetic separation are grouped in a gravity field, and the minerals in the group with a large specific gravity and large particle size are used as the raw materials for grouping after gravity separation for niobium ore flotation to obtain rough niobium concentrate; the rough niobium concentrate is subjected to magnetic separation to obtain high-grade niobium concentrate. The method of the invention adopts a physical and chemical property grouping and separation method. By grouping niobium minerals and complex gangue minerals, the types of gangue are gradually reduced, providing a suitable separation environment for niobium recovery, significantly improving the separation efficiency of niobium minerals, and significantly increasing the grade and recovery rate of niobium concentrate.

Description

Technical Field

[0001] The present invention belongs to the field of niobium ore beneficiation, and particularly relates to a beneficiation method for enriching and obtaining niobium concentrate. Background Art

[0002] Niobium is an important key metal indispensable in modern industry and cutting-edge technologies. Niobium has a high melting point, corrosion resistance, and low-temperature superconductivity. Niobium can greatly improve the mechanical strength and toughness of steel, and make steel lighter and lower in cost. It is widely used in manufacturing oil and gas pipelines, automotive components, pressure vessels, ships, heavy steel rails, high-strength steel bars used in large hydropower stations, etc. In addition, niobium superalloy materials can be used for a long time at temperatures above 650 degrees Celsius in oxidative and corrosive atmospheres. The superalloys can be used in combustion equipment, nuclear reactor cores, rocket parts, and jet engine components, etc.

[0003] China's niobium resources amount to 9.27 million tons calculated by Nb2O5. However, most of the niobium resources are characterized by a large variety of niobium-containing minerals, wide distribution, low grade, fine dissemination, complex and close dissemination relationship with other minerals and high dispersion. At the same time, the process properties of niobium minerals have little difference from those of other minerals, making it difficult to achieve effective recovery of niobium resources. Therefore, China is highly dependent on imports of niobium metal, with a foreign dependence of over 99%. It is of great significance and urgency to study the beneficiation and recovery of niobium from low-grade, fine-grained, and complex niobium-containing ores. Since the 1960s, Chinese scientific research personnel have carried out a large amount of work on the niobium ore recovery beneficiation process and separation reagents in Bayan Obo, the largest niobium resource base in China, but have not achieved good results. Either high-grade niobium concentrate cannot be obtained, or the recovery rate is extremely low and niobium resources cannot be effectively recovered, or the cost of pyrometallurgical and hydrometallurgical processes is too high, etc. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to overcome the above-mentioned deficiencies and defects in the background art, and provide a beneficiation method for supernormal enrichment to obtain niobium concentrate. This method uses a physical and chemical property grouping and separation method to group niobium minerals (such as those in Bayan Obo) and complex gangue minerals, gradually reducing the types of gangue, providing a suitable separation environment for niobium recovery, significantly improving the separation efficiency of niobium minerals, and significantly increasing the grade and recovery rate of niobium concentrate.

[0005] To solve the above technical problem, the technical solution proposed by the present invention is a beneficiation method for supernormal enrichment to obtain niobium concentrate, including the following steps:

[0006] S1: Grind the raw ore to obtain a grinding product; subject the grinding product to magnetic separation, and use the weakly magnetic minerals after magnetic separation as the raw material for grouping after magnetic separation;

[0007] S2: Group the raw materials after magnetic separation in a gravitational field, and use the mineral part of the group with a large specific gravity and large particle size as the raw materials after gravity separation. The equipment for gravity separation is preferably one or a combination of a shaking table, a spiral chute, and a centrifuge;

[0008] S3: Perform niobium ore flotation on the raw materials after gravity separation above to obtain rough niobium concentrate;

[0009] S4: Perform magnetic separation on the rough niobium concentrate above to obtain high-grade niobium concentrate.

[0010] In the above technical solution of the present invention, grouping is first performed by magnetic separation, and then grouping is performed by gravity separation. For the mineral part with a large specific gravity and large particle size, a flotation - re - magnetic separation process is further used to obtain high - grade niobium concentrate.

[0011] For the above beneficiation method, preferably, the magnetic separation in step S1 includes: first performing a primary magnetic grouping in a weak magnetic field, removing the strongly magnetic mineral part after the primary magnetic grouping as gangue, and using the weakly magnetic and non - magnetic mineral part after the primary magnetic grouping as the raw materials for the primary magnetic grouping;

[0012] Then perform a secondary magnetic grouping on the raw materials for the primary magnetic grouping in a strong magnetic field, removing the non - magnetic mineral part after the secondary magnetic grouping as gangue, and using the weakly magnetic mineral part after the secondary magnetic grouping as the raw materials after magnetic separation.

[0013] For the above beneficiation method, preferably, the magnetic field intensity for the primary magnetic grouping in the weak magnetic field is 1200 - 2000 Oe, and the feed mass concentration is 15% - 25%; the magnetic field intensity for the secondary magnetic grouping in the strong magnetic field is 12000 - 22000 Oe, and the feed mass concentration is 15% - 25%.

[0014] For the above beneficiation method, preferably, in step S2, the grouping in the gravitational field specifically refers to dividing the raw materials after magnetic separation into a group with a large specific gravity and large particle size, a group with a small specific gravity and small particle size, and the remaining intermediate group in the gravitational field: the mineral part of the group with a small specific gravity and small particle size is removed as gangue; the remaining intermediate group is the remaining minerals after removing the mineral part of the group with a large specific gravity and large particle size and the mineral part of the group with a small specific gravity and small particle size. The mineral part of the remaining intermediate group is sequentially recovered for secondary niobium concentrate through screening, desliming, secondary gravity separation, and niobium mineral flotation. The group with a large specific gravity and large particle size preferably refers to the mineral part with a mineral particle specific gravity ≥ 4 and a particle size ≥ 38 μm; the group with a small specific gravity and small particle size preferably refers to the mineral part with a mineral particle specific gravity < 4 and a particle size < 38 μm, and the remaining mineral part can be used as the remaining intermediate group.

[0015] In the above technical solution of the present invention, through magnetic separation, gravity separation, and coarse and fine classification, etc., the low-grade complex niobium ore is grouped multiple times, gradually reducing the types of gangue minerals, changing the niobium ore separation environment, and improving the niobium ore separation efficiency. Especially in the preferred solution, classification is also carried out through weak magnetic field and strong magnetic field, and it is further subdivided into three mineral groups during gravity separation. While reducing the types of gangue minerals, this also improves the niobium ore separation efficiency and recovery rate.

[0016] In the above beneficiation method, preferably, the screening specifically includes the screening process of a high-frequency fine screen. The coarse-grained minerals in the oversize part are used as gangue, and the fine-grained minerals in the undersize part are used as desliming raw materials; the aperture of the screen mesh used in the high-frequency fine screen screening process is 325 mesh to 400 mesh.

[0017] In the above beneficiation method, preferably, the desliming specifically includes the strong dispersion sedimentation desliming and classification process. Part of the slime after desliming is used as tailings, and part of the sand after desliming is used as the raw material for secondary gravity separation.

[0018] More preferably, in the strong dispersion sedimentation desliming and classification process, a stirrer is placed in an ultrasonic container to ultrasonically strongly disperse the pulp in a uniform state.

[0019] In the above preferred solution, stirring and ultrasonic waves are used for strong dispersion selective desliming of fine-grained niobium ore. The deslimed and sand minerals belong to fine and narrow particle size ores, which greatly improves the efficiency of centrifugal separation and enrichment of fine-grained niobium ore, providing a prerequisite for obtaining secondary niobium concentrate.

[0020] More preferably, in the strong dispersion sedimentation desliming and classification process, the rotation speed of the stirrer is 500 - 1000 rpm, the ultrasonic power of the ultrasonic container is 40 - 80 W, the ultrasonic frequency is 45 - 80 Hz; the mass concentration of the strongly dispersed deslimed pulp is 10% - 20%, the dispersant used is water glass, the dispersion time is 10 - 15 min, and the sedimentation time is 4 - 10 min.

[0021] In the above beneficiation method, preferably, the secondary gravity separation is centrifugal gravity separation. The flushing water volume of the centrifugal gravity separation is 4 L / min to 7 L / min, the rotation speed is 200 rpm to 500 rpm, and the concentrate obtained by centrifugal gravity separation is fine-grained niobium rough concentrate; the fine-grained niobium rough concentrate is subjected to fine-grained niobium ore flotation to obtain secondary niobium concentrate.

[0022] In the above beneficiation method, preferably, in step S1, the grinding fineness of the grinding product is controlled such that the content of the -75μm particle size fraction accounts for 60% - 100% of the total grinding amount. The total amount of monomeric and rich intergrown niobium minerals in the grinding product is greater than 75%.

[0023] For the above beneficiation method, preferably, in step S3, the flotation sequentially includes two steps: desulfurization flotation and niobium mineral flotation;

[0024] In the desulfurization flotation step, butyl xanthate is selected as the collector, No. 2 oil is selected as the foaming agent, and sodium hexametaphosphate and water glass are selected as the dispersants; the flotation time is controlled to be 3 - 6 min, the flotation concentration is controlled to be 30% - 40%, the flotation process is one roughing and one cleaning, and the middlings in the flotation cleaning are merged into the niobium mineral flotation step;

[0025] In the niobium mineral flotation step, hydroxamic acid is selected as the collector, and ammonium fluorosilicate or water glass is selected as the regulator; the flotation process is one roughing and three cleanings, and finally a rough niobium concentrate is obtained.

[0026] For the above beneficiation method, preferably, in the fine-grained niobium ore flotation step, a combination of sodium oleate and hydroxamic acid (the most preferred ratio of sodium oleate to hydroxamic acid is 1:1) is selected as the collector, and ammonium fluorosilicate or PDC (a composition of water glass and tannin with a ratio of 1:1) is selected as the regulator; the flotation process is one roughing and three cleanings, and finally a rough niobium concentrate is obtained.

[0027] For the above beneficiation method, preferably, in step S4, the magnetic separation magnetic field intensity is 3000 - 6000 Oe, the feed mass concentration is 15% - 25%, and the tailings from the magnetic separation are merged into the secondary niobium concentrate.

[0028] In the above preferred embodiment of the present invention, high-grade niobium concentrate is recovered from the heavy coarse-grained part of the minerals by specific gravity, and at the same time, the fine-grained niobium minerals that are easily lost are sorted and recovered by narrow particle size, obtaining secondary niobium concentrate. The comprehensive application of the two process routes greatly improves the comprehensive recovery rate of niobium ore.

[0029] In the above preferred embodiment of the present invention, preferably, there is no roasting process in the beneficiation method, and there is no acid leaching process in the beneficiation method.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] In the technical solution of the present invention, the minerals are grouped and sorted according to their physical and chemical properties. In the most preferred process route, it can be further divided into strongly magnetic minerals, weakly magnetic minerals, non-magnetic minerals, large specific gravity minerals in weakly magnetic minerals, small specific gravity minerals in weakly magnetic minerals, fine-grained large specific gravity minerals, coarse-grained small specific gravity minerals, etc. They are classified layer by layer and sorted separately. High-grade niobium concentrate is obtained for easily separable minerals. For the fine-grained niobium ore that is easily lost in the middlings of the gravity separation grouping, high-frequency fine screens are used to remove coarse-grained gangue, and strong dispersion and desliming are used to remove the extremely fine slime that affects the separation. Sub-niobium concentrate is obtained by the narrow-grade flotation separation method. Compared with other niobium ore beneficiation methods, the present invention does not require beneficiation operations that have a greater impact on the environment, such as roasting and acid leaching of minerals, and the energy consumption and acid consumption are significantly reduced. It has the advantages of good environmental protection, high recovery rate, and strong adaptability. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 It is a schematic diagram of the beneficiation process flow for the embodiment of the present invention.

[0034] Figure 2 It is a schematic diagram of the beneficiation process flow for Comparative Example 1 of the present invention.

[0035] Figure 3 It is a schematic diagram of the beneficiation process flow for Comparative Example 2 of the present invention.

[0036] Figure 4 It is a schematic diagram of the beneficiation process flow for Comparative Example 3 of the present invention.

[0037] Figure 5 It is a schematic diagram of the beneficiation process flow for Comparative Example 4 of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0038] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and meticulously in conjunction with the accompanying drawings of the specification and the preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0039] Unless otherwise defined, all the technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0040] Unless otherwise specified, various raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchases or prepared by existing methods.

[0041] Example 1:

[0042] The raw material mineral composition and MLA analysis results used in Example 1 of the present invention are shown in Table 1 and Table 2 below, respectively.

[0043] Table 1: Analysis Results of Feed Mineral Composition in Example / %

[0044] Mineral Name Mica Amphibole Talc Pyrite Quartz Dolomite Fluorite Others Total Mineral Content 10.82 7.28 0.88 4.81 2.94 42.16 3.41 27.7 100.00

[0045] Table 2: Analysis Results of Niobium Phase in Feed of Example / %

[0046]

[0047] A beneficiation method for obtaining high-grade niobium concentrate by extraordinary enrichment of the present invention to improve niobium recovery rate, the flow chart of which is as Figure 1 shown, specifically including the following steps:

[0048] (1) Weak magnetic field magnetic grouping: Under the condition that the feed mass concentration is 50%, grinding is carried out until the fineness of -0.075mm accounts for 78.00% (mass fraction) of the total grinding amount, and the total amount of niobium mineral monomers and rich intergrowths in the grinding product is greater than 75%; when the grinding product is adjusted to a mass concentration of 20%, it is grouped three times in magnetic fields with weak magnetic field intensities of 1200 Oe, 1400 Oe, and 1600 Oe. The weakly magnetic or non-magnetic mineral products enter the strong magnetic field, and the combined strongly magnetic mineral products enter the tailings;

[0049] (2) Strong magnetic field magnetic grouping: The weakly magnetic or non-magnetic mineral products in step (1) are adjusted to a mass concentration of 20% and enter the strong magnetic field, and are grouped three times in magnetic fields with strong magnetic field intensities of 12000 Oe, 16000 Oe, and 18000 Oe. The weakly magnetic mineral products enter the next gravitational field, and the non-magnetic mineral products enter the tailings;

[0050] (3) Gravity field gravity grouping: The weakly magnetic mineral products after high-intensity magnetic separation in step (2) enter a shaking table for gravity grouping to obtain three groups of products: minerals with a large specific gravity and large particle size, minerals with a small specific gravity and small particle size, and the remaining intermediate group minerals (mixed minerals of large specific gravity and small particle size and small specific gravity and large particle size). The mineral products in the group with a large specific gravity and large particle size enter the next niobium ore flotation step. The mixed mineral products of large specific gravity and small particle size and small specific gravity and large particle size enter screening and classification, and the mineral products in the group with a small specific gravity and small particle size enter the tailings. In this embodiment, the group with a large specific gravity and large particle size refers to the mineral part with a specific gravity of the mineral particles ≥4 and a particle size ≥38 μm; the group with a small specific gravity and small particle size refers to the mineral part with a specific gravity of the mineral particles <4 and a particle size <38 μm, and the remaining mineral part can be used as the remaining intermediate group;

[0051] (4) Niobium ore flotation: The mineral products in the group with a large specific gravity and large particle size obtained by gravity grouping in the shaking table in step (3) enter the flotation operation. The niobium ore flotation includes two steps: flotation desulfurization and niobium mineral flotation in sequence;

[0052] Among them, butyl xanthate is selected as the collector, No. 2 oil is selected as the foaming agent, and water glass is selected as the dispersant for flotation desulfurization; the flotation process is one roughing and one cleaning. The roughing dosages are 200 g / t, 25 g / t, and 1000 g / t respectively, and the cleaning dosages are 100 g / t, 12.5 g / t, and 0 g / t respectively;

[0053] In the niobium mineral flotation step, alkyl hydroxamic acid is selected as the collector, ammonium fluorosilicate and water glass are selected as regulators; the flotation process is one roughing and three cleanings. The roughing dosages of ammonium fluorosilicate, water glass, and alkyl hydroxamic acid are 1000 g / t, 2000 g / t, and 1500 g / t respectively; the cleaning dosages are 500 g / t, 1000 g / t, and 800 g / t respectively; the roughing time is 5 min, and the flotation concentration is 35%; the cleaning time is 3 min, and the flotation concentration is 30%;

[0054] The grade of niobium rough concentrate Nb2O5 reaches 6.64%, and the flotation tailings enter the final tailings;

[0055] (5) The niobium rough concentrate enters magnetic separation. The feed mass concentration is 20%, and the magnetic field intensity is 4000 Oe, obtaining high-grade niobium concentrate with a recovery rate of 25.03% to the original ore and a Nb2O5 grade of 10.08%. The magnetic separation tailings are merged into the secondary niobium concentrate;

[0056] (6) Separation of the remaining intermediate group mineral products: Part of the products of the mixed minerals of large specific gravity and small particle size and small specific gravity and large particle size obtained by gravity grouping in the shaking table in step (3) above enter high-frequency fine screening and classification. The aperture of the fine screen mesh is 325 mesh (45 μm). The +45 μm oversize products enter the tailings, and the -45 μm undersize products enter the next de-sludging step;

[0057] (7) Dewatering: Dewatering specifically includes the process of strong dispersion sedimentation dewatering and classification. Part of the dewatered ore sludge is used as tailings, and part of the dewatered sand is used as the raw material for secondary gravity separation. The process of strong dispersion sedimentation dewatering and classification is to place a stirrer in an ultrasonic container to ultrasonically strongly disperse the pulp in a uniform state. During the process of strong dispersion sedimentation dewatering and classification, the rotation speed of the dispersion stirrer is 1000 rpm, the ultrasonic power is 40 W, the ultrasonic frequency is 45 Hz, and the dispersion time is 10 min. The mass concentration of the strongly dispersed dewatered pulp is 20%, the dosage of the dispersant sodium silicate used is 2000 g / t, and the sedimentation time is 5 min; the ore sludge enters the final tailings, and the dewatered sand enters the next centrifugal gravity separation;

[0058] (8) Secondary gravity separation: The secondary gravity separation is centrifugal gravity separation. The flushing water volume for centrifugal gravity separation is 5 L / min, the rotation speed is 200 rpm. After centrifugal gravity separation, the part with a larger specific gravity is used as the fine niobium rough concentrate and enters the next step of fine niobium ore flotation;

[0059] (9) Fine niobium ore flotation: The fine niobium rough concentrate obtained in step (8) is concentrated to a pulp with a concentration of 35% for fine niobium ore flotation. The reagents are ammonium fluorosilicate, PDC, and alkylhydroxamic acid. The roughing dosages are 1000 g / t, 1000 g / t, and 1200 g / t respectively; the cleaning dosages are 500 g / t, 500 g / t, and 800 g / t respectively. The grade of the niobium concentrate Nb2O5 reaches 2.37%, and the flotation tailings enter the final tailings.

[0060] In this embodiment, the raw ore with a grade of Nb2O5 of 0.068% is processed by the beneficiation method, and the specific corresponding test indexes are shown in Table 3. Niobium concentrate with a grade of Nb2O5 of 10.08% and a recovery rate of 25.03% for the raw ore and secondary niobium concentrate with a grade of Nb2O5 of 2.37% and a recovery rate of 10.03% for the raw ore can be obtained. For low-grade niobium ore, through the extraordinary enrichment method, high-grade niobium concentrate is obtained, and the enrichment ratio reaches nearly 150 times; the narrow-grade recovery of fine secondary niobium concentrate makes the overall comprehensive recovery rate of niobium concentrate reach 35%.

[0061] Table 3: Test result table of Example 1

[0062] Product Name Yield / % <![CDATA[Nb2O5 grade / %]]> <![CDATA[Recovery rate of Nb2O5 / %]]> High - grade Niobium Concentrate 0.17 10.08 25.15 Sub - niobium Concentrate 0.29 2.37 10.09 Flotation Tailings 0.87 0.86 10.98 Screening - desliming Tailings 2.95 0.56 24.25 Gravity Separation Tailings 48.36 0.023 16.32 Magnetic Separation Tailings 47.36 0.019 13.21 Feed 100.00 0.068 100.00

[0063] Example 2:

[0064] The raw material mineral composition and MLA analysis results used in Example 2 of the present invention are shown in Table 4 and Table 5 below respectively.

[0065] Table 4: Analysis results of the feed mineral composition in Example 2 / %

[0066]

[0067]

[0068] Table 5: Results of niobium phase analysis in the feed of Example 2 / %

[0069] Niobium Minerals Columbite Pyrochlore Aeschynite Niobium Ferrotitanate and Other Niobium Total Distribution Ratio 83.95 8.15 4.94 2.96 100.00

[0070] A beneficiation method for obtaining high-grade niobium concentrate by super enrichment of the present invention to improve niobium recovery rate, the flow chart of which is as Figure 1 shown, specifically including the following steps:

[0071] (1) Weak magnetic field magnetic grouping: Under the condition that the feed mass concentration is 50%, grinding is carried out until the fineness of -0.075mm accounts for 80.00% (mass fraction) of the total grinding amount, and the total amount of niobium mineral monomers and rich intergrowths in the grinding product is 82.35%; when the grinding product is adjusted to a mass concentration of 25%, three groupings are carried out in magnetic fields with weak magnetic field intensities of 1200Oe, 1600Oe, and 2000Oe. The weakly magnetic or non-magnetic mineral products enter the strong magnetic field, and the combined strong magnetic mineral products enter the tailings;

[0072] (2) Strong magnetic field magnetic grouping: The weakly magnetic or non-magnetic mineral products in step (1) are adjusted to a mass concentration of 25% and enter the strong magnetic field. Three groupings are carried out in magnetic fields with strong magnetic field intensities of 12000Oe, 16000Oe, and 20000Oe. The weakly magnetic mineral products enter the next gravitational field, and the non-magnetic mineral products enter the tailings;

[0073] (3) Gravity grouping in the gravitational field: The weakly magnetic mineral products after strong magnetic separation in step (2) enter the shaking table for gravity grouping to obtain three groups of products: minerals with a large specific gravity and large particle size, minerals with a small specific gravity and small particle size, and the remaining intermediate group minerals (mixed minerals of minerals with a large specific gravity and small particle size and minerals with a small specific gravity and large particle size). The mineral products with a large specific gravity and large particle size enter the next niobium ore flotation, the mixed mineral products of minerals with a large specific gravity and small particle size and minerals with a small specific gravity and large particle size enter screening and classification, and the mineral products with a small specific gravity and small particle size enter the tailings. In this embodiment, the group with a large specific gravity and large particle size refers to the mineral part with a mineral particle specific gravity ≥ 4 and a particle size ≥ 38μm; the group with a small specific gravity and small particle size refers to the mineral part with a mineral particle specific gravity < 4 and a particle size < 38μm, and the remaining mineral part can be used as the remaining intermediate group;

[0074] (4) Niobium ore flotation: The mineral products with a large specific gravity and large particle size obtained by gravity grouping in the shaking table in step (3) enter the flotation operation, and the niobium ore flotation sequentially includes two steps: flotation desulfurization and niobium mineral flotation;

[0075] Among them, for flotation desulfurization, butyl xanthate is selected as the collector, No. 2 oil as the frother, and water glass as the dispersant; the flotation process is one roughing and one cleaning, and the roughing dosages are 200 g / t, 25 g / t, and 1000 g / t respectively, and the cleaning dosages are 100 g / t, 12.5 g / t, and 0 g / t respectively;

[0076] In the niobium mineral flotation step, alkyl hydroxamic acid is selected as the collector, and ammonium fluorosilicate and water glass are used as regulators; the flotation process is one roughing and three cleanings. The roughing dosages of ammonium fluorosilicate, water glass, and alkyl hydroxamic acid are 1000 g / t, 2000 g / t, and 1500 g / t respectively; the cleaning dosages are 500 g / t, 1000 g / t, and 800 g / t respectively; the roughing time is 5 min, and the flotation concentration is 35%; the cleaning time is 4 min, and the flotation concentration is 35%, obtaining a rough concentrate of floated niobium, and the flotation tailings enter the final tailings;

[0077] (5) The rough concentrate of niobium enters magnetic separation, the feed mass concentration is 20%, and the magnetic field intensity is 4000 Oe, obtaining a high-grade niobium concentrate with a recovery rate of 24.85% to the original ore and a Nb2O5 grade of 11.60%, and the magnetic separation tailings are merged into the secondary niobium concentrate;

[0078] (6) Separation of other intermediate group mineral products: The mixed mineral part products of the group with a large specific gravity and small particle size and the group with a small specific gravity and large particle size obtained by the gravity field grouping of the shaking table in the above step (3) enter high-frequency fine screening for classification. The aperture of the fine screen mesh is 325 mesh (45 μm), the +45 μm oversize products enter the tailings, and the -45 μm undersize products enter the next desliming;

[0079] (7) Desliming: Desliming specifically includes a strong dispersion sedimentation desliming and classification process. The slime part after desliming is used as tailings, and the sand part after desliming is used as the raw material for secondary gravity separation. The strong dispersion sedimentation desliming and classification process is to place a stirrer in an ultrasonic container to ultrasonically strongly disperse the pulp in a uniform state. During the strong dispersion sedimentation desliming and classification process, the rotation speed of the dispersion stirrer is 800 rpm, the ultrasonic power is 40 W, the ultrasonic frequency is 45 Hz, and the dispersion time is 10 min. The mass concentration of the strongly dispersed desliming pulp is 20%, the dosage of the dispersant water glass used is 2000 g / t, and the sedimentation time is 5 min; the slime enters the final tailings, and the deslimed sand enters the next centrifugal gravity separation;

[0080] (8) Secondary gravity separation: The secondary gravity separation is centrifugal gravity separation. The washing water volume of the centrifugal gravity separation is 5 L / min, and the rotation speed is 200 rpm. After centrifugal gravity separation, the part with a large specific gravity is used as the rough concentrate of fine-grained niobium and enters the next flotation of fine-grained niobium ore;

[0081] (9) Flotation of fine niobium ore: The coarse concentrate of fine niobium obtained in step (8) is concentrated to a pulp with a concentration of 35% for the flotation of fine niobium ore. The reagents are ammonium fluorosilicate, PDC, and alkylhydroxamic acid. The roughing dosages are 1000 g / t, 1000 g / t, and 1200 g / t respectively; the cleaning dosages are 500 g / t, 500 g / t, and 800 g / t respectively. The grade of niobium concentrate Nb2O5 reaches 2.20%, and the flotation tailings enter the final tailings.

[0082] In this example, the raw ore with a grade of Nb2O5 of 0.06% is treated by a beneficiation method. The specific corresponding test indexes are shown in Table 6. Niobium concentrate with a grade of Nb2O5 of 11.60% and a recovery rate of 24.85% for the raw ore and secondary niobium concentrate with a grade of Nb2O5 of 2.20% and a recovery rate of 10.68% for the raw ore can be obtained.

[0083] Table 6: Test result table of Example 2

[0084] Product Name Yield / % <![CDATA[Nb2O5 grade / %]]> <![CDATA[Recovery rate of Nb2O5 / %]]> High - grade Niobium Concentrate 0.13 11.60 25.15 Sub - niobium Concentrate 0.29 2.20 10.64 Flotation Tailings 0.87 0.77 11.17 Screening - desliming Tailings 2.18 0.56 20.36 Gravity Separation Tailings 44.40 0.023 17.03 Magnetic Separation Tailings 52.13 0.018 15.65 Feed 100.00 0.06 100.00

[0085] In Example 1 and Example 2, conventional methods such as magnetic separation, gravity separation, flotation, and sieving are used to recover niobium ore resources by extraordinary enrichment. No other organic acids or inorganic acid chemical substances are added, and no roasting conversion and acid leaching technologies are used. The energy consumption is small and there is no acid consumption.

[0086] Comparative Example 1:

[0087] The beneficiation process of low-grade niobium ore in Comparative Example 1 is: reduction roasting - magnetic separation - gravity separation - niobium mineral flotation (the process is shown in Figure 2 ). Using this process to treat the ore sample of Example 1, the process parameter conditions of weak magnetic separation - gravity separation and niobium flotation steps are basically the same as those of Example 1. The corresponding test indexes obtained are: the grade of niobium concentrate Nb2O5 is 2.39% and the recovery rate for the raw ore is 26.98%. In the experimental process, the raw ore is roasted at 800 °C for 30 min, and then the process of weak magnetic separation - gravity separation - niobium mineral flotation is used for separation. The energy consumption of its roasting is about 35 kgce / t (kilogram standard coal / ton).

[0088] It can be seen that compared with the traditional reduction roasting - magnetic separation - gravity separation - flotation process, the present invention greatly improves the grade and recovery rate of niobium concentrate. Because the roasting process is not used, there is no discharge of CO2 and sulfide gases formed by the decomposition of carbonates and sulfides in the ore, which has advantages in environmental protection. In addition, there are also significant advantages in terms of energy consumption.

[0089] Comparative Example 2:

[0090] The beneficiation process of low-grade niobium ore in Comparative Example 2 is: weak magnetic separation - strong magnetic separation - gravity separation - flotation - acid leaching (the process is shown in Figure 3), The process parameters of magnetic separation, gravity separation, and niobium flotation steps for processing the ore sample of Example 1 using this process are basically the same as those of Example 1. The corresponding test indexes obtained are as follows: the grade of Nb2O5 in niobium concentrate is 7.05%, and the recovery rate for the original ore is 24.80%. In this experimental process, the rough concentrate of flotation is leached with hydrochloric acid for 2 hours, and the acid consumption for the rough concentrate of flotation is 5 kg / t.

[0091] Therefore, compared with the traditional reduction roasting - magnetic separation - gravity separation - flotation process, the present invention greatly improves the grade and recovery rate of niobium concentrate. Since the acid leaching process is not used, there is no discharge of acidic waste liquid, and it has significant advantages in environmental protection.

[0092] Comparative Example 3:

[0093] The beneficiation process of low - grade niobium ore for Comparative Example 3 is: weak magnetic separation - strong magnetic separation - niobium mineral flotation (the process flow is shown in Figure 4 ). Using this process to process the ore sample of Example 1, the process parameter conditions of each step are basically the same as those of Example 1. The corresponding test indexes obtained are as follows: the grade of Nb2O5 in niobium concentrate is 2.39%, and the recovery rate for the original ore is 26.98%.

[0094] Comparative Example 4:

[0095] The beneficiation process of low - grade niobium ore for Comparative Example 4 is: weak magnetic separation - strong magnetic separation - gravity separation - niobium mineral flotation (the process flow is shown in Figure 5 ). Using this process to process the ore sample of Example 1, the process parameter conditions of each step are basically the same as those of Example 1. The corresponding test indexes obtained are as follows: the grade of Nb2O5 in niobium concentrate is 5.05%, and the recovery rate for the original ore is 24.80%.

Claims

1. A beneficiation method for obtaining niobium concentrate by extraordinary enrichment, characterized in that, It includes the following steps: S1: Grind the raw ore to obtain a ground product; perform magnetic separation on the ground product, and use the weakly magnetic minerals after magnetic separation as the grouped raw materials after magnetic separation; the distribution rate of columbite in the raw ore is 63.86% or 83.95%; S2: Group the grouped raw materials after magnetic separation in a gravitational field, and use the mineral part of the group with a large specific gravity and large particle size as the grouped raw materials after gravity separation; The grouping in the gravitational field specifically means dividing the grouped raw materials after magnetic separation into a group with a large specific gravity and large particle size, a group with a small specific gravity and small particle size, and the remaining intermediate group in the gravitational field: the mineral part of the group with a small specific gravity and small particle size is discarded as gangue; the remaining intermediate group is the remaining minerals after removing the mineral part of the group with a large specific gravity and large particle size and the mineral part of the group with a small specific gravity and small particle size. The mineral part of the remaining intermediate group is successively recovered as secondary niobium concentrate through screening, desliming, secondary gravity separation, and fine-grained niobium ore flotation; The group with a large specific gravity and large particle size refers to the mineral part with a mineral particle specific gravity ≥ 4 and a particle size ≥ 38 μm; the group with a small specific gravity and small particle size refers to the mineral part with a mineral particle specific gravity < 4 and a particle size < 38 μm; S3: Perform niobium ore flotation on the grouped raw materials after the above gravity separation to obtain rough niobium concentrate; S4: Perform magnetic separation on the above rough niobium concentrate to obtain high-grade niobium concentrate.

2. The ore dressing method according to claim 1, wherein The magnetic separation in step S1 includes: first perform primary magnetic grouping in a weak magnetic field, discard the strongly magnetic mineral part after primary magnetic grouping as gangue, and use the weakly magnetic and non-magnetic mineral part after primary magnetic grouping as the raw material for primary magnetic grouping; then perform secondary magnetic grouping on the raw material for primary magnetic grouping in a strong magnetic field, discard the non-magnetic mineral part after secondary magnetic grouping as gangue, and use the weakly magnetic mineral part after secondary magnetic grouping as the grouped raw materials after magnetic separation.

3. The ore dressing method according to claim 2, wherein The magnetic field intensity for performing primary magnetic grouping in the weak magnetic field is 1200 - 2000 Oe, and the feed mass concentration is 15% - 25%; the magnetic field intensity for performing secondary magnetic grouping in the strong magnetic field is 12000 - 22000 Oe, and the feed mass concentration is 15% - 25%.

4. The ore dressing method according to claim 1, characterized in that, The screening specifically includes the screening process of a high-frequency fine screen. The coarse-grained minerals on the screen are used as gangue, and the fine-grained minerals under the screen are used as the raw materials for desliming; the aperture of the screen used in the screening process of the high-frequency fine screen is 325 mesh - 400 mesh.

5. The ore dressing method according to claim 1, characterized in that The desliming specifically includes the strong dispersion sedimentation desliming and classification process. The slime part after desliming is used as tailings, and the sand part after desliming is used as the raw material for secondary gravity separation.

6. The ore dressing method according to claim 5, wherein The strong dispersion sedimentation desliming and classification process is to place a stirrer in an ultrasonic container to ultrasonically strongly disperse the pulp in a uniform state.

7. The ore dressing method according to claim 6, characterized in that, In the strong dispersion sedimentation desliming and classification process, the rotation speed of the stirrer is 500 - 1000 rpm, the ultrasonic power of the ultrasonic container is 40 - 80 W, and the ultrasonic frequency is 45 - 80 Hz; the mass concentration of the strongly dispersed desliming pulp is 10% - 20%, the dispersant used is water glass, the dispersion time is 10 - 15 min, and the sedimentation time is 4 - 10 min.

8. The ore dressing method according to any one of claims 1 to 7, characterized in that, The secondary re - selection is centrifugal re - selection. The flushing water volume of the centrifugal re - selection is 4 L / min to 7 L / min, the rotational speed is 200 rpm to 500 rpm, and the concentrate obtained by centrifugal re - selection is fine - grained niobium rough concentrate; the fine - grained niobium rough concentrate is subjected to fine - grained niobium ore flotation to obtain secondary niobium concentrate.

9. The ore dressing method according to any one of claims 1 to 7, characterized in that, In step S1, the grinding fineness of the grinding product is controlled such that the content of the - 75μm particle size fraction accounts for 60% to 100% of the total grinding amount; the total amount of niobium mineral monomers and rich intergrowths in the grinding product is greater than 75%.

10. The ore dressing method according to any one of claims 1 to 7, characterized in that In step S3, the flotation successively includes two steps of flotation desulfurization and niobium mineral flotation; in the flotation desulfurization step, butyl xanthate is selected as the collector, No. 2 oil is selected as the frother, sodium hexametaphosphate and water glass are selected as dispersants; the flotation time is controlled to be 3 to 6 min, the flotation concentration is controlled to be 30% to 40%, the flotation process is one roughing and one cleaning, and the middlings in the flotation cleaning are merged into the niobium mineral flotation step; In the niobium mineral flotation step, hydroxamic acid is selected as the collector, ammonium fluorosilicate and / or water glass are selected as regulators; the flotation process is one roughing and three cleanings, and finally niobium rough concentrate is obtained; In the fine - grained niobium ore flotation step, a combination of sodium oleate and hydroxamic acid is selected as the collector, and ammonium fluorosilicate or PDC is selected as the regulator; the flotation process is one roughing and three cleanings, and finally niobium rough concentrate is obtained.

11. The ore dressing method according to any one of claims 1 to 7, characterized in that, In step S4, the magnetic field intensity for magnetic separation is 3000 to 6000 Oe, the feed mass concentration is 15% to 25%, and the tailings from magnetic separation are merged into the secondary niobium concentrate .

12. The ore dressing method according to any one of claims 1 to 7, characterized in that, There is no roasting process in the ore dressing method, and there is no acid leaching process in the ore dressing method.

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