An efficient method for separating niobium from silicate-type low-grade niobium ore.

Abstract

This invention relates to an efficient separation method for niobium in silicate-type low-grade niobium ore, belonging to the field of mineral processing technology. It solves the problems of low niobium concentrate grade and yield, and / or complex operation methods obtained by existing methods. The method includes: sequentially performing primary grinding, primary weak magnetic separation, primary gravity column desliming, secondary gravity column separation, desulfurization flotation, secondary grinding until the material mass ratio of particles smaller than 0.074 mm is 90%-95%, primary roughing, primary scavenging, and primary cleaning rare earth flotation, and primary roughing and primary cleaning niobium flotation. The niobium flotation reagents are: an activator of a mixture of zinc nitrate and lead nitrate; a depressant of a mixture of carboxymethyl cellulose, aminoethyl starch, and sodium humate with a substitution degree ≥0.8; a collector of a mixture of salicylic acid, benzoic acid, and 8-hydroxyquinoline; and a frother of terpineol; followed by secondary weak magnetic separation to obtain niobium concentrate. This method achieves a high overall niobium recovery rate and niobium concentrate grade, and the method is simple.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, and in particular to a highly efficient method for separating niobium in silicate-type low-grade niobium ore. Background Technology

[0002] The Bayan Obo mine is a super-large deposit containing niobium, rare earth elements, and iron. The grade of niobium minerals in the main Bayan Obo mine is low, only 0.1%-0.15%, with fine grain size and an average particle size of less than 50 μm. It contains a variety of niobium minerals, including about 20 kinds such as calcite, columbite, pyrochlore, and columbite-rutile. Moreover, the mineral selectivity differences between niobium minerals and gangue minerals are small, and the coexistence is complex, making the recovery of niobium resources quite difficult.

[0003] Existing methods for niobium mineral recovery mainly focus on two types: combined beneficiation and metallurgical methods, and pure beneficiation separation. For example, the combined beneficiation and metallurgical method involves weak magnetic separation, strong magnetic separation pre-enrichment, fluidized bed roasting, weak magnetic separation, rare earth flotation, and acid leaching to obtain niobium-rich slag. This process requires roasting and acid leaching, making it complex to operate. Existing pure beneficiation methods for niobium separation primarily target the rare earth tailings from Bayan Obo. This involves first performing rare earth flotation on the raw ore, and then further processing the rare earth tailings from the rare earth flotation into mixed flotation, strong magnetic separation, a first-stage sulfur flotation, and a first-stage iron positive flotation. The process of separation-gravity separation-two-stage sulfur flotation-two-stage iron positive flotation-niobium flotation can yield niobium concentrate with a niobium grade of 5.7% and a niobium recovery rate of 40%. However, this recovery rate is for rare earth tailings. For raw ore, the niobium recovery rate (overall niobium recovery rate) is only below 10%, which is not good. In addition, the process is too long and not easy to operate stably on site. Another method is to use the anephrite-type ore from Bayan Obo East Mine as raw material and adopt a weak magnetic-rare earth flotation-niobium flotation process, which finally yields a niobium concentrate with a grade of about 1%, which is relatively low. Summary of the Invention

[0004] Based on the above analysis, the embodiments of the present invention aim to provide an efficient separation method for niobium in silicate-type low-grade niobium ores, in order to solve the problems of low grade and yield of niobium concentrate and / or complex operation methods obtained by existing niobium mineral recovery methods.

[0005] This invention provides a method for efficient separation of niobium in silicate-type low-grade niobium ore, the method comprising the following steps: Step (1): The raw ore is ground once, and the raw ore after grinding is subjected to weak magnetic separation once to obtain iron concentrate and tailings after magnetic separation; in the raw ore, the niobium grade is 0.10%-0.15%, and easily calcified niobium minerals account for more than 40% of the volume content of niobium-containing minerals in the raw ore. Step (2): The tailings from the first magnetic separation are deslimed by a first gravity column to obtain slime and deslimed concentrate from the first gravity separation. The deslimed concentrate from the first gravity separation is then separated by a second gravity column to obtain light minerals and secondary gravity sediment. Step (3) involves desulfurizing and flotating the secondary gravity separation sediment to obtain sulfur tailings and sulfur concentrate; Step (4) involves secondary grinding of the sulfur tailings until the mass percentage of material with a particle size less than 0.074 mm is 90%-95%. Step (5) involves rare earth flotation of the material after secondary grinding, which includes rare earth roughing, rare earth scavenging, rare earth primary cleaning, rare earth secondary cleaning, rare earth tertiary cleaning and rare earth quaternary cleaning in sequence. Step (6): The rare earth tailings, middlings from the first, second, third, and fourth rare earth cleaning processes obtained from the rare earth flotation are mixed and then subjected to niobium flotation. The niobium flotation includes niobium roughing, niobium primary cleaning, niobium secondary cleaning, niobium tertiary cleaning, and niobium quaternary cleaning performed sequentially. The reagents for the niobium flotation include: activator, inhibitor, collector, and frother. The activator is a mixture of zinc nitrate and lead nitrate. The inhibitor is a mixture of carboxymethyl cellulose, aminoethyl starch, and sodium humate with a degree of substitution ≥0.8. The collector is a mixture of salicylic acid, benzoic acid, and 8-hydroxyquinoline. The frother is terpineol. Step (7): The niobium concentrate obtained from the fourth niobium refining process is subjected to a second weak magnetic separation to obtain niobium concentrate.

[0006] Preferably, in step (1), the primary grinding process involves grinding the raw ore until the mass ratio of the material with a particle size of less than 0.074 mm is 85%-90%.

[0007] Preferably, in step (1), the magnetic field strength of the first weak magnetic separation is 159.1-199.0 kA / m.

[0008] Preferably, in step (2), the conditions for the primary gravity column desliming include: feed concentration of 15wt%-20wt%, feed pump speed of 280-330rpm, rising water flow rate of 40-45L / h, and underflow pump speed of 40-45rpm.

[0009] Preferably, in step (2), the conditions for secondary gravity separation include: feed concentration of 25wt%-30wt%, feed pump speed of 280-330rpm, rising water flow rate of 40-45L / h, replenishment water flow rate of 10-15L / h, and underflow pump speed of 35-40rpm.

[0010] Preferably, in step (3), the desulfurization flotation includes desulfurization roughing and desulfurization cleaning; sulfuric acid, butyl xanthate and terpineol are added to the secondary gravity separation sediment for desulfurization roughing to obtain sulfur rough concentrate and sulfur rough tailings; the sulfur rough concentrate is desulfurized and cleaned to obtain sulfur concentrate and sulfur middlings, the sulfur middlings are returned to the desulfurization roughing step, and the sulfur rough tailings are entered into step (4) as sulfur tailings; And / or, the conditions for the desulfurization roughing process include: feed concentration of 45wt%-50wt%, sulfuric acid dosage of 0.1-0.15kg / t, butyl xanthate dosage of 2-2.5kg / t, and terpineol dosage of 10-30g / t; And / or, the desulfurization and beneficiation conditions include: a feed concentration of 45wt%-50wt%, with no reagents added.

[0011] Preferably, in step (5), the conditions for the rare earth roughing include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 1-1.5kg / t, pH adjuster dosage of 0.3-0.6kg / t, collector dosage of 2.2-2.8kg / t, and frother dosage of 0.1-0.2kg / t; And / or, the conditions for rare earth scavenging include: flotation temperature of 60-65℃, inhibitor dosage of 0.4-0.8 kg / t, pH adjuster dosage of 0.1-0.2 kg / t, collector dosage of 1.2-2 kg / t, and frother dosage of 0.15-0.25 kg / t.

[0012] Preferably, in step (5), the conditions for the primary rare earth refining include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.35-0.45kg / t, pH adjuster dosage of 0.1-0.2kg / t, collector dosage of 1.2-2kg / t, and frother dosage of 0.15-0.25kg / t; And / or, the conditions for the secondary rare earth refining include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.25-0.38kg / t, collector dosage of 0.7-1.3kg / t, and frother dosage of 0.1-0.2kg / t; And / or, the conditions for the three-stage rare earth refining process include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.2-0.3kg / t, collector dosage of 0.8-1.2kg / t, and frother dosage of 0.08-0.16kg / t; And / or, the conditions for the four-stage rare earth refining process include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.1-0.2kg / t, collector dosage of 0.3-0.8kg / t, and frother dosage of 0.02-0.1kg / t.

[0013] Preferably, in step (6), the conditions for the roughing of niobium include: flotation concentration of 40wt%-45wt%, flotation temperature of 60-65℃, activator dosage of 1-1.5kg / t, inhibitor dosage of 0.3-0.8kg / t, collector dosage of 5-6kg / t, and frother dosage of 20-50g / t; And / or, the conditions for the primary niobium refining include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.5-1.0kg / t; And / or, the conditions for the secondary niobium refining include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.3-0.8kg / t; And / or, the conditions for the three-stage niobium refining process include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.1-0.5kg / t; And / or, the conditions for the fourth niobium refining process include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.02-0.08kg / t.

[0014] Preferably, in step (6), the mass ratio of zinc nitrate to lead nitrate in the activator is 1-1.5:4-3.5; And / or, the mass ratio of carboxymethyl cellulose, aminoethyl starch, and sodium humate in the inhibitor is 7-8:1-0.5:2-1.5; And / or, the mass ratio of salicylic acid, benzoic acid, and 8-hydroxyquinoline in the collector is 5-6:3-2:1-2.

[0015] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects: 1. In the method of this invention, the raw ore is directly used as the separation raw material. After grinding the raw ore, a primary weak magnetic separation is used to separate the magnetic iron minerals in the raw ore. The tailings obtained from the primary magnetic separation are then deslimed by a primary gravity column and separated by a secondary gravity column. The gravity concentrate is enriched with heavy minerals such as niobium minerals. The separation of light minerals such as carbonate minerals reduces the influence of carbonate minerals on subsequent flotation. The content of easily calcified niobium minerals in the gravity concentrate is further increased, thereby improving the homogeneity of niobium minerals and providing favorable conditions for subsequent niobium flotation. The gravity concentrate undergoes desulfurization flotation to reduce the impact of pyrite on subsequent niobium flotation. The sulfur tailings are ground until the material mass ratio of particles smaller than 0.074mm is 90%-95%, then subjected to a four-stage rare earth flotation process (roughing, scavenging, and cleaning) to remove the influence of rare earth on niobium flotation while recovering rare earths. The rare earth flotation tailings, combined with specific niobium flotation reagents, undergo a four-stage niobium flotation process, followed by secondary weak magnetic separation, ultimately yielding a niobium concentrate with an Nb₂O₅ grade of over 5%, achieving a niobium recovery rate of over 25% throughout the entire process. This invention pre-enriches the easily calcified niobium minerals in the raw ore to diversify the niobium mineral composition. Then, specific niobium flotation reagents are used in the niobium flotation process, resulting in an increase of over 40% in the easily calcified niobium content in the final niobium concentrate compared to the raw ore (the easily calcified niobium minerals account for over 84% of the total niobium-containing minerals in the final niobium concentrate). This effectively separates the easily calcified niobium minerals, thereby improving the overall niobium recovery rate and the grade of the niobium concentrate.

[0016] 2. The method of the present invention only involves magnetic separation, gravity separation, desulfurization and flotation processes, and does not involve complex processes such as roasting and acid leaching. The method is simple and easy to implement.

[0017] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages may become apparent from the description or be learned by practicing the invention. The objects and other advantages of this invention can be realized and obtained from what is particularly pointed out in the description and drawings. Attached Figure Description

[0018] The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Throughout the drawings, the same reference numerals denote the same parts.

[0019] Figure 1 This is a schematic diagram of the process for efficient separation of niobium in silicate-type low-grade niobium ore according to the present invention. Detailed Implementation

[0020] Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, which form part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, but are not intended to limit the scope of the present invention.

[0021] Studies have revealed that the niobium mineral grade in the Bayan Obo main ore deposit is low, ranging from only 0.1% to 0.15%; the embedded grain size is fine, with an average particle size of less than 50 μm; and there is a high variety of niobium minerals, including approximately 20 types such as calcite, columbite, pyrochlore, and columbite-rutile, which exhibit complex symbiotic relationships with gangue minerals such as iron and silicate minerals, making separation extremely difficult. In the Bayan Obo main ore deposit, calcite, a niobium-bearing mineral associated with silicates, has a larger particle size than other niobium-bearing minerals during ore formation, thus requiring separate storage of this type of ore. Further research found that calcite niobium minerals account for more than 40% of the niobium mineral volume content in this low-grade silicate-type niobium ore. If the niobium mineral types in the raw ore can be made as homogeneous as possible, and the over-grinding and mudding of calcite niobium minerals can be minimized—that is, if the homogeneity of niobium minerals after pre-enrichment is improved with minimal loss of niobium recovery—the flotation efficiency of niobium minerals can be enhanced. The main design principle of the sorting process in this invention is to utilize easily calcified niobium minerals, which are readily ground and become muddy, and have extremely weak magnetic properties (specific magnetic susceptibility 14.75 × 10⁻⁶). 6 m 3 / kg), relatively high density (5.5g / cm³) 3 Starting from the physical properties of niobium (left and right), we aim to maximize the enrichment effect of easily calcified niobium minerals, thereby improving the overall niobium recovery rate and niobium concentrate grade.

[0022] Based on this, the present invention provides a highly efficient method for separating niobium in silicate-type low-grade niobium ore, such as... Figure 1 As shown, the method includes the following steps: Step (1): The raw ore is ground once, and the raw ore after grinding is subjected to weak magnetic separation once to obtain iron concentrate and tailings from the first magnetic separation; in the raw ore, the niobium grade is 0.10%-0.15% (e.g., 0.10%, 0.11%, 0.12%, 0.13%, 0.14%, 0.15%), and easily calcified niobium minerals account for more than 40% of the volume content of niobium-containing minerals in the raw ore; it should be noted that this volume content refers to the mineral content data measured by the mineral liberation analyzer (MLA); Step (2): The tailings from the first magnetic separation are deslimed by a first gravity column to obtain slime and deslimed concentrate from the first gravity separation. The deslimed concentrate from the first gravity separation is then separated by a second gravity column to obtain light minerals and secondary gravity sediment. Step (3) involves desulfurizing and flotating the secondary gravity separation sediment to obtain sulfur tailings and sulfur concentrate; Step (4) involves secondary grinding of the sulfur tailings until the mass ratio of the material with a particle size of less than 0.074 mm is 90%-95% (e.g., 90%, 91%, 92%, 93%, 94%, 95%). Step (5) involves rare earth flotation of the material after secondary grinding, which includes rare earth roughing, rare earth scavenging, rare earth primary cleaning, rare earth secondary cleaning, rare earth tertiary cleaning and rare earth quaternary cleaning in sequence. Step (6): The rare earth tailings, middlings from the first, second, third, and fourth rare earth cleaning processes obtained from the rare earth flotation are mixed and then subjected to niobium flotation. The niobium flotation includes niobium roughing, niobium primary cleaning, niobium secondary cleaning, niobium tertiary cleaning, and niobium quaternary cleaning performed sequentially. The reagents for the niobium flotation include: activator, inhibitor, collector, and frother. The activator is a mixture of zinc nitrate and lead nitrate. The inhibitor is a mixture of carboxymethyl cellulose, aminoethyl starch, and sodium humate with a degree of substitution ≥0.8. The collector is a mixture of salicylic acid, benzoic acid, and 8-hydroxyquinoline. The frother is terpineol. Step (7): The niobium concentrate obtained from the fourth niobium refining process is subjected to a second weak magnetic separation to obtain niobium concentrate.

[0023] Compared with existing technologies, the efficient separation method for niobium in silicate-type low-grade niobium ore of the present invention improves the homogeneity of easily calcified niobium minerals in the ore through one grinding, one weak magnetic separation, one gravity column desliming, and two gravity column separations. Since coarse-grained heavy minerals such as rare earth elements and easily calcified niobium minerals are enriched after gravity separation, the particle size is relatively coarse and the mineral liberation is poor, which affects the flotation effect. Therefore, after desulfurization, a second grinding is performed to ensure that the mass ratio of material with a particle size of less than 0.074 mm is 90%-95%, which can guarantee the flotation effect of rare earth elements and niobium. At the same time, in the niobium flotation, specific reagents are used to enrich the easily calcified niobium mineral ore, resulting in a high niobium grade in the niobium concentrate and a high niobium recovery rate throughout the process. Moreover, the method is simple and easy to implement.

[0024] It should be noted that the processing sequence of the first weak magnetic separation, the first gravity column desliming, the second gravity column separation, and the desulfurization flotation of the present invention is designed for the specific silicate-type low-grade niobium ore of the present invention. Changing the order of any step will affect the enrichment effect of easily calcified niobium minerals.

[0025] For example, in step (1), the first grinding is to grind the raw ore until the mass ratio of the material with a particle size of less than 0.074 mm is 85%-90% (e.g., 85%, 86%, 87%, 88%, 89%, 90%). This first grinding condition can ensure that the removal effect of magnetic iron is good when the easily calcified niobium minerals are not ground as much as possible and the niobium loss is minimized.

[0026] In step (1) of the present invention, the calcite niobium mineral accounts for more than 40% of the niobium mineral content in the raw ore, and the calcite is not magnetic. In order to initially enrich the calcite niobium mineral, the magnetic iron mineral in the raw ore is separated by a weak magnetic separation. In the magnetic separation tailings, the niobium mineral (especially the calcite niobium mineral) is enriched.

[0027] For example, in step (1), the magnetic field strength of the primary weak magnetic separation is 159.1-199.0 kA / m, such as 159.1, 160.0 kA / m, 170.0 kA / m, 180.0 kA / m, and 199.0 kA / m. If the magnetic field strength is too high, it will lead to a large loss of niobium; if the magnetic field strength is too low, the separation effect of magnetic iron will be affected.

[0028] In step (2) of this invention, the tailings from the primary magnetic separation contain a large amount of calcium-containing light minerals, which have a significant density difference from niobium minerals, and also contain a large amount of fine particles smaller than 10 μm, which has a significant impact on the subsequent niobium beneficiation process. Therefore, a primary gravity column desliming and a secondary gravity column separation are performed to remove the calcium-containing light minerals first, so as to ensure the subsequent niobium flotation operation. After the efficient gravity separation of primary gravity column desliming and secondary gravity column separation, the niobium minerals are enriched in the heavy minerals, and the easily calcified minerals are even more enriched in the niobium minerals, making the composition of niobium minerals in the subsequent feed relatively simpler, providing favorable conditions for the subsequent niobium flotation.

[0029] For example, in step (2), the conditions for the primary gravity column desliming include: a feed concentration of 15wt%-20wt% (e.g., 15wt%, 16wt%, 17wt%, 18wt%, 19wt%, 20wt%), a feed pump speed of 280-330rpm (e.g., 280rpm, 300rpm, 320rpm, 330rpm), a riser flow rate of 40-45L / h (e.g., 40L / h, 42L / h, 44L / h, 45L / h), and an underflow pump speed of 40-45rpm (e.g., 40rpm, 42rpm, 44rpm, 45rpm). If the feed concentration, feed pump speed, and rising water flow rate are too high, the amount of fine sludge removed will increase, and the niobium loss will increase; if the feed concentration, feed pump speed, and rising water flow rate are too low, the equipment desliming efficiency will be low and the separation effect will be poor; when the underflow pump speed is not within the above-mentioned preferred range, it will have the opposite effect to the above-mentioned feed concentration, feed pump speed, and rising water flow rate.

[0030] For example, in step (2), the conditions for the secondary gravity separation column separation include: a feed concentration of 25wt%-30wt% (e.g., 25wt%, 26wt%, 27wt%, 28wt%, 29wt%, 30wt%), a feed pump speed of 280-330rpm (e.g., 280rpm, 300rpm, 320rpm, 330rpm), a riser flow rate of 40-45L / h (e.g., 40L / h, 42L / h, 44L / h, 45L / h), a makeup water flow rate of 10-15L / h (e.g., 10L / h, 12L / h, 14L / h, 15L / h), and an underflow pump speed of 35-40rpm (e.g., 35rpm, 37rpm, 39rpm, 40rpm). If the feed concentration, feed pump speed, and rising water flow rate are too high, more light minerals such as calcium-containing minerals will be discarded, and the niobium loss will increase; if the feed concentration, feed pump speed, and rising water flow rate are too low, the equipment's separation effect will deteriorate; when the underflow pump speed is not within the above-mentioned preferred range, it has the opposite effect to the above-mentioned feed concentration, feed pump speed, and rising water flow rate.

[0031] In step (3) of the present invention, since the secondary gravity separation sediment contains heavy mineral pyrite, in order to avoid the influence of pyrite on the subsequent niobium flotation, the secondary gravity separation sediment is subjected to desulfurization flotation.

[0032] For example, in step (3), the desulfurization flotation includes desulfurization roughing and desulfurization cleaning, specifically including: adding sulfuric acid, butyl xanthate and terpineol to the secondary gravity separation sediment for desulfurization roughing to obtain sulfur rough concentrate and sulfur rough tailings; performing desulfurization cleaning on the sulfur rough concentrate, without adding reagents in the desulfurization cleaning process, to obtain sulfur concentrate and sulfur middlings, returning the sulfur middlings to the desulfurization roughing step, and the sulfur rough tailings as sulfur tailings entering step (4).

[0033] The purpose of the desulfurization roughing process is to initially enrich sulfur-containing minerals such as pyrite in the secondary gravity separation sediment to obtain sulfur rough concentrate and sulfur rough tailings. The purpose of the desulfurization cleaning process is to obtain sulfur concentrate with a sulfur grade greater than 35%. The sulfur middlings are returned to the desulfurization roughing process to improve the sulfur concentrate recovery rate.

[0034] For example, in step (3), the conditions for desulfurization roughing include: feed concentration of 45wt%-50wt% (e.g., 45wt%, 46wt%, 47wt%, 48wt%, 49wt%, 50wt%), sulfuric acid dosage of 0.1-0.15kg / t (e.g., 0.1kg / t, 0.12kg / t, 0.14kg / t, 0.15kg / t), butyl xanthate dosage of 2-2.5kg / t (e.g., 2kg / t, 2.2kg / t, 2.4kg / t, 2.5kg / t), and terpineol dosage of 10-30g / t (e.g., 10g / t, 15g / t, 20g / t, 25g / t, 30g / t); when all conditions are below the limit, the sulfur removal effect is poor, and when they are above the limit, the loss of easily calcified niobium minerals is large.

[0035] For example, the terpineol is No. 2 oil, purchased from Shandong Qicheng Qingquan Ecological Technology Co., Ltd.

[0036] For example, the conditions for desulfurization and beneficiation include a feed concentration of 45wt%-50wt%, such as 45wt%, 47wt%, 49wt%, and 50wt%. No reagents are added during desulfurization and beneficiation, as the reagents used in the roughing process are sufficient to ensure beneficiation and separation.

[0037] In step (4) of the present invention, the mass ratio of material with a particle size of less than 0.074 mm after secondary grinding is 90%-95%. If the particle size is too small, it will lead to mud formation of easily calcified minerals, which is not conducive to the recovery of easily calcified niobium minerals and results in a large loss of niobium.

[0038] In step (5) of the present invention, the rare earth flotation specifically includes: Step (51): The material after the secondary grinding is subjected to rare earth roughing to obtain rare earth roughing tailings and rare earth roughing concentrate. Step (52): The rare earth roughing tailings are subjected to rare earth scavenging to obtain rare earth scavenged tailings and rare earth scavenged concentrate; Step (53): After merging the rare earth roughing concentrate and the rare earth scavenging concentrate, perform a first-stage rare earth refining process to obtain the first-stage rare earth middlings and the first-stage rare earth concentrate. Step (54): Perform a second rare earth refining process on the primary rare earth concentrate to obtain secondary rare earth middlings and secondary rare earth concentrate. Step (55): Perform rare earth tertiary refining on the rare earth secondary refining concentrate to obtain rare earth tertiary refining middlings and rare earth tertiary refining concentrate; Step (56): Perform a fourth rare earth refining process on the rare earth concentrate obtained from the third rare earth refining process to obtain the rare earth middlings and the rare earth concentrate obtained from the fourth rare earth refining process.

[0039] The rare earth flotation process of roughing, scavenging and refining can not only further enrich niobium minerals and reduce the impact of rare earths on niobium flotation, but also make the rare earth concentrate obtained after four rounds of refining reach a rare earth grade of more than 55%.

[0040] For example, in step (5), the conditions for rare earth roughing include: a flotation concentration of 55wt%-65wt% (e.g., 55wt%, 57wt%, 59wt%, 61wt%, 63wt%, 65wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), and an inhibitor dosage of 1-1.5kg / t (e.g., 1kg / t, 1.2kg / t, 1.4kg / t, 1.5kg / t). The dosage of pH adjuster is 0.3-0.6 kg / t (e.g., 0.3 kg / t, 0.4 kg / t, 0.5 kg / t, 0.6 kg / t), the dosage of collector is 2.2-2.8 kg / t (e.g., 2.2 kg / t, 2.4 kg / t, 2.6 kg / t, 2.8 kg / t), and the dosage of foaming agent is 0.1-0.2 kg / t (e.g., 0.1 kg / t, 0.15 kg / t, 0.2 kg / t).

[0041] For example, in step (5), the conditions for rare earth scavenging include: a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), an inhibitor dosage of 0.4-0.8 kg / t (e.g., 0.4 kg / t, 0.5 kg / t, 0.6 kg / t, 0.7 kg / t, 0.8 kg / t), and a pH adjuster dosage of 0.1-0.2 kg / t (e.g., 0.1 kg / t, 0.2 kg / t). The dosage of the collector is 1.2-2 kg / t (e.g., 1.2 kg / t, 1.4 kg / t, 1.6 kg / t, 1.8 kg / t, 2 kg / t), and the dosage of the foaming agent is 0.15-0.25 kg / t (e.g., 0.15 kg / t, 0.17 kg / t, 0.19 kg / t, 0.2 kg / t, 0.22 kg / t, 0.25 kg / t).

[0042] For example, in step (5), the conditions for the primary rare earth refining include: a flotation concentration of 55wt%-65wt% (e.g., 55wt%, 57wt%, 59wt%, 61wt%, 63wt%, 65wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), and an inhibitor dosage of 0.35-0.45kg / t (e.g., 0.35kg / t, 0.37kg / t, 0.39kg / t, 0.41kg / t, 0.43kg / t, 0.45kg). The dosage of pH adjuster is 0.1-0.2 kg / t (e.g., 0.1 kg / t, 0.15 kg / t, 0.2 kg / t), the dosage of collector is 1.2-2 kg / t (e.g., 1.2 kg / t, 1.4 kg / t, 1.6 kg / t, 1.8 kg / t, 2 kg / t), and the dosage of foaming agent is 0.15-0.25 kg / t (e.g., 0.15 kg / t, 0.17 kg / t, 0.19 kg / t, 0.2 kg / t, 0.22 kg / t, 0.25 kg / t).

[0043] For example, in step (5), the conditions for the secondary rare earth refining include: a flotation concentration of 55wt%-65wt% (e.g., 55wt%, 57wt%, 59wt%, 61wt%, 63wt%, 65wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), and an inhibitor dosage of 0.25-0.38kg / t (e.g., 0.25kg / t, 0.27kg / t). The dosages are 0.29 kg / t, 0.31 kg / t, 0.33 kg / t, 0.35 kg / t, and 0.38 kg / t, respectively. The dosage of the collector is 0.7-1.3 kg / t (e.g., 0.7 kg / t, 0.9 kg / t, 1.1 kg / t, and 1.3 kg / t), and the dosage of the foaming agent is 0.1-0.2 kg / t (e.g., 0.1 kg / t, 0.15 kg / t, and 0.2 kg / t).

[0044] For example, in step (5), the conditions for the three-stage rare earth refining include: a flotation concentration of 55wt%-65wt% (e.g., 55wt%, 57wt%, 59wt%, 61wt%, 63wt%, 65wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), an inhibitor dosage of 0.2-0.3kg / t (e.g., 0.2kg / t, 0.25kg / t, 0.3kg / t), a collector dosage of 0.8-1.2kg / t (e.g., 0.8kg / t, 0.9kg / t, 1.0kg / t, 1.2kg / t), and a frother dosage of 0.08-0.16kg / t (e.g., 0.08kg / t, 0.10kg / t, 0.12kg / t, 0.14kg / t, 0.16kg / t).

[0045] For example, in step (5), the conditions for the four-stage rare earth refining include: a flotation concentration of 55wt%-65wt% (e.g., 55wt%, 57wt%, 59wt%, 61wt%, 63wt%, 65wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), an inhibitor dosage of 0.1-0.2kg / t (e.g., 0.1kg / t, 0.15kg / t, 0.2kg / t), a collector dosage of 0.3-0.8kg / t (e.g., 0.3kg / t, 0.5kg / t, 0.7kg / t, 0.8kg / t), and a frother dosage of 0.02-0.1kg / t (e.g., 0.02kg / t, 0.04kg / t, 0.06kg / t, 0.08kg / t, 0.1kg / t).

[0046] In the above rare earth flotation conditions, if the values ​​of each condition are too low, the rare earth will be lost in the tailings, affecting the effect of the next niobium flotation and the enrichment effect of easily calcified niobium minerals. If the values ​​of each condition are too high, the loss of easily calcified niobium minerals will be greater.

[0047] For example, in step (5), the inhibitor is water glass, the pH adjuster is sulfuric acid, the collector is LF-P8 (purchased from Inner Mongolia Lingfeng Technology Co., Ltd.), and the foaming agent is terpineol (2# oil, purchased from Shandong Qicheng Qingquan Ecological Technology Co., Ltd.).

[0048] It should be noted that in this invention, the sulfuric acid is added in the form of a 5% sulfuric acid solution; the amount of sulfuric acid used is calculated based on the mass of the sulfuric acid solute in the sulfuric acid solution.

[0049] In step (6) of the present invention, niobium minerals are separated through a roughing and refining niobium flotation process. Specifically, the niobium flotation includes: Step (61): In order to improve the recovery rate of easily calcified niobium minerals in niobium flotation, the rare earth scavenging tailings, rare earth primary cleaning middlings, rare earth secondary cleaning middlings, rare earth tertiary cleaning middlings, and rare earth quaternary cleaning middlings obtained from the rare earth flotation are mixed and then subjected to niobium roughing to obtain niobium roughing tailings and niobium roughing concentrate. Step (62): The niobium roughing concentrate is subjected to niobium primary cleaning to obtain niobium primary cleaning middlings and niobium primary cleaning concentrate; Step (63): The niobium primary concentrate is subjected to niobium secondary concentrate to obtain niobium secondary concentrate middlings and niobium secondary concentrate. Step (64): The niobium secondary concentrate is subjected to niobium tertiary concentrate to obtain niobium tertiary concentrate middlings and niobium tertiary concentrate. Step (65): The niobium concentrate from the third-stage refining process is subjected to a fourth-stage refining process to obtain niobium middlings and niobium concentrate from the fourth-stage refining process.

[0050] For example, the niobium flotation further includes: combining the middlings from the third and fourth niobium cleaning processes and returning them to the niobium roughing process for a closed-circuit test.

[0051] For example, in step (6), the conditions for the niobium roughing include: a flotation concentration of 40wt%-45wt% (e.g., 40wt%, 42wt%, 44wt%, 45wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), an activator dosage of 1-1.5kg / t (e.g., 1kg / t, 1.2kg / t, 1.4kg / t, 1.5kg / t), an inhibitor dosage of 0.3-0.8kg / t (e.g., 0.3kg / t, 0.5kg / t, 0.7kg / t, 0.8kg / t), a collector dosage of 5-6kg / t (e.g., 5kg / t, 5.4kg / t, 5.8kg / t, 6kg / t), and a frother dosage of 20-50g / t (e.g., 20g / t, 30g / t, 40g / t, 50g / t).

[0052] For example, in step (6), the conditions for the primary niobium selection include: a flotation concentration of 40wt%-45wt% (e.g., 40wt%, 42wt%, 44wt%, 45wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), and an inhibitor dosage of 0.5-1.0kg / t (e.g., 0.5kg / t, 0.7kg / t, 0.9kg / t, 1.0kg / t).

[0053] For example, in step (6), the conditions for the secondary niobium refining include: a flotation concentration of 40wt%-45wt% (e.g., 40wt%, 42wt%, 44wt%, 45wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), and an inhibitor dosage of 0.3-0.8kg / t (e.g., 0.3kg / t, 0.5kg / t, 0.7kg / t, 0.8kg / t).

[0054] For example, in step (6), the conditions for the three-stage niobium refining include: a flotation concentration of 40wt%-45wt% (e.g., 40wt%, 42wt%, 44wt%, 45wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), and an inhibitor dosage of 0.1-0.5kg / t (e.g., 0.1kg / t, 0.2kg / t, 0.3kg / t, 0.4kg / t, 0.5kg / t).

[0055] For example, in step (6), the conditions for the four-stage niobium refining include: a flotation concentration of 40wt%-45wt% (e.g., 40wt%, 42wt%, 44wt%, 45wt%), a flotation temperature of 60-65℃ (e.g., 60℃, 62℃, 64℃, 65℃), and an inhibitor dosage of 0.02-0.08kg / t (e.g., 0.02kg / t, 0.04kg / t, 0.06kg / t, 0.08kg / t).

[0056] In the above niobium flotation conditions, if the values ​​of each condition are too low, the separation effect of easily calcified niobium minerals will be poor, and there will be a lot of loss in the tailings. If the values ​​of each condition are too high, the grade of niobium concentrate and the enrichment rate of easily calcified niobium minerals will be affected.

[0057] For example, in step (6), the mass ratio of zinc nitrate to lead nitrate in the activator is 1-1.5:4-3.5, such as 1:4, 1:3.5, 1.5:4, 1.5:3.5.

[0058] For example, in step (6), the mass ratio of carboxymethyl cellulose, aminoethyl starch and sodium humate in the inhibitor is 7-8:1-0.5:2-1.5, such as 7:1:2, 7:0.5:1.5, 8:1:2, 8:0.5:1.5.

[0059] For example, in step (6), the mass ratio of salicylic acid, benzoic acid and 8-hydroxyquinoline in the collector is 5-6:3-2:1-2, such as 5:3:1, 5:2:2, 5:3:2, 6:3:1, 6:2:2 and 6:3:2.

[0060] For example, in step (6), the foaming agent is terpineol (2# oil, purchased from Shandong Qicheng Qingquan Ecological Technology Co., Ltd.).

[0061] In step (7) of the present invention, since magnetite and niobium minerals are intergrowthed, and since iron is a transition metal, it is less sensitive to reagents, but there are differences in magnetic physical properties between it and easily calcified niobium minerals. Therefore, it can be removed by weak magnetic separation. The purpose of secondary weak magnetic separation is to further remove magnetic minerals, improve the grade of niobium concentrate and the content of easily calcified minerals.

[0062] For example, the magnetic field strength of the secondary weak magnetic separation is 119.4-159.2 kA / m, such as 119.4 kA / m, 120.0 kA / m, 130.0 kA / m, 140.0 kA / m, 150.0 kA / m, and 159.2 kA / m. The secondary weak magnetic separation has a slightly lower magnetic field strength than the primary weak magnetic separation, which improves the grade of niobium concentrate while reducing the loss of easily calcified niobium minerals.

[0063] For example, the magnetic field strength of the secondary magnetic weakening separation is 15-40 kA / m lower than that of the primary magnetic weakening separation. For instance, the difference in magnetic field strength between the two is 15 kA / m, 20 kA / m, 30 kA / m, or 40 kA / m.

[0064] The following specific embodiments illustrate the efficient niobium separation method for silicate-type low-grade niobium ore according to the present invention.

[0065] The raw ore used in the following examples and comparative examples is a silicate-type low-grade niobium ore from Inner Mongolia. Its chemical composition analysis is shown in Table 1, its iron mineral composition analysis is shown in Table 2, and its geological MLA analysis is shown in Table 3.

[0066] Table 1

[0067] Table 2

[0068] Table 3

[0069] As shown in Table 2, the iron-bearing minerals contain 74.02% magnetite. As shown in Table 3, the niobium-bearing minerals in the raw ore are mainly calcite, baotou ore, pyrochlore, niobite-rutile, and columbite. Among them, calcite has the highest content, accounting for about 42% of the total niobium-bearing minerals, followed by baotou ore, accounting for about 24% of the total niobium-bearing minerals, and then pyrochlore and niobite-rutile, accounting for about 14% and 13% of the total niobium-bearing minerals, respectively.

[0070] Example 1 This embodiment provides a highly efficient method for separating niobium in silicate-type low-grade niobium ore, including: Step (1): The raw ore is ground once until the material mass ratio of the particle size less than 0.074mm is 87%. The raw ore after the first grinding is subjected to a weak magnetic separation with a magnetic field strength of 159.16kA / m to obtain iron concentrate and tailings from the first magnetic separation. The results of the first weak magnetic separation are shown in Table 4.

[0071] Table 4

[0072] As shown in Table 4, niobium minerals were enriched in the tailings from the first magnetic separation. The tailings from the first magnetic separation contained a large amount of calcium-containing light minerals, accounting for about 30% of the total minerals. The content of minerals with a particle size of less than 10 μm accounted for more than 10%, which had a significant impact on the subsequent niobium separation. Therefore, gravity separation was carried out.

[0073] Step (2): The tailings from the primary magnetic separation are subjected to primary gravity column desliming with a feed concentration of 20 wt%, a feed pump speed of 300 rpm, a riser water flow rate of 40 L / h, and a bottom flow pump speed of 40 rpm to obtain slime and primary gravity desliming concentrate. The primary gravity desliming concentrate is then subjected to secondary gravity column separation with a feed concentration of 30 wt%, a feed pump speed of 300 rpm, a riser water flow rate of 40 L / h, a makeup water flow rate of 10 L / h, and a bottom flow pump speed of 40 rpm to obtain light minerals and secondary gravity sediment. The results of continuous gravity column separation are shown in Table 5.

[0074] Table 5

[0075] As shown in Table 5, after continuous separation by the gravity column, a slime with a yield of 15.29% was obtained, containing 8.59% rare earth elements and 0.13% niobium. The rare earth element content in the secondary gravity separation sediment was 21.81% (69.34% yield), and the niobium content was 0.28% (64.34% yield). The Nb₂O₅ content in the light mineral tailings was 0.088% (23.89% yield), and the rare earth element grade was 5.30% (19.91% yield). The low Nb₂O₅ content in the light mineral tailings indicates that the continuous gravity separation process effectively enriched the niobium minerals.

[0076] Step (3): Sulfuric acid, butyl xanthate, and No. 2 oil are added to the secondary gravity separation sediment for desulfurization roughing. The feed concentration is 50.00 wt%, the amount of sulfuric acid is 0.1 kg / t, the amount of butyl xanthate is 2 kg / t, and the amount of No. 2 oil is 10 g / t, to obtain sulfur rough concentrate and sulfur rough tailings. The sulfur rough concentrate is then desulfurized and refined. The feed concentration is 50 wt%. No reagents are added during the desulfurization and refinement process, to obtain sulfur concentrate and sulfur middlings. The desulfurization flotation results are shown in Table 6.

[0077] Table 6

[0078] As shown in Table 6, after one roughing and one cleaning desulfurization flotation, the sulfur concentrate yield was 4.08%, the sulfur concentrate grade was 37.34%, and the recovery rate was 37.89%. In the sulfur concentrate, the niobium grade was 0.083% with a recovery rate of 1.21%, and the rare earth grade was 8.36% with a recovery rate of 1.59%.

[0079] Step (4): The sulfur middlings are returned to the desulfurization roughing process for a closed-circuit test. The sulfur tailings are then subjected to secondary grinding using an ISA mill until the material mass ratio of particles smaller than 0.074 mm is 95%.

[0080] Step (5) involves rare earth flotation of the material after secondary grinding, specifically including: Step (51): Rare earth roughing is performed on the material after the secondary grinding to obtain rare earth roughing tailings and rare earth roughing concentrate; the conditions for rare earth roughing are: flotation concentration 60wt%, flotation temperature 65℃, water glass dosage 1.30kg / t, sulfuric acid 0.52kg / t, LF-P8 collector dosage 2.5kg / t, and No. 2 oil dosage 0.16kg / t. Step (52): Rare earth scavenging is performed on the rare earth roughing tailings to obtain rare earth scavenged tailings and rare earth scavenged concentrate. Rare earth scavenging conditions: flotation temperature 65℃, water glass dosage 0.59kg / t, sulfuric acid 0.16kg / t, LF-P8 collector dosage 1.7kg / t, and No. 2 oil dosage 0.22kg / t. Step (53): The rare earth roughing concentrate and the rare earth scavenging concentrate are combined and then subjected to primary rare earth refining to obtain primary rare earth middlings and primary rare earth concentrate. The conditions for primary rare earth refining are: flotation concentration 60wt%, flotation temperature 65℃, water glass dosage 0.37kg / t, sulfuric acid 0.13kg / t, LF-P8 collector dosage 1.5kg / t, and No. 2 oil dosage 0.18kg / t. Step (54): The rare earth primary concentrate is subjected to rare earth secondary refining to obtain rare earth secondary refining middlings and rare earth secondary refining concentrate; the conditions for rare earth secondary refining are: flotation concentration 60wt%, flotation temperature 65℃, water glass dosage 0.35kg / t, LF-P8 collector dosage 1.12kg / t, and No. 2 oil dosage 0.15kg / t. Step (55): The rare earth secondary concentrate is subjected to rare earth tertiary refining to obtain rare earth middlings and rare earth tertiary concentrate; the conditions for rare earth tertiary refining are: flotation concentration 60wt%, flotation temperature 65℃, water glass dosage 0.25kg / t, LF-P8 collector dosage 0.88kg / t, and No. 2 oil dosage 0.10kg / t. Step (56): The rare earth concentrate from the three-stage rare earth refining process is subjected to a fourth-stage rare earth refining process to obtain middlings and concentrate from the fourth-stage rare earth refining process. The conditions for the fourth-stage rare earth refining process are: flotation concentration 60 wt%, flotation temperature 65℃, water glass dosage 0.15 kg / t, LF-P8 collector dosage 0.5 kg / t, and No. 2 oil dosage 0.05 kg / t. The results of rare earth flotation are shown in Table 7.

[0081] Table 7

[0082] As shown in Table 7, after one roughing, one scavenging, and four cleaning processes in rare earth flotation, the final rare earth concentrate grade was 56.34%, with a yield of 81.22%. The Nb₂O₅ grade in the final rare earth concentrate was 0.099%, with a yield of 11.15%. The mixture of rare earth scavenging tailings and middlings from the first, second, third, and fourth cleaning processes was used as feed for niobium flotation. The Nb₂O₅ grade in this mixture was 0.364%, with a yield of 88.84%, and the rare earth grade was 6.02%, with a yield of 18.79%.

[0083] Step (6) involves mixing the rare earth scavenging tailings, rare earth primary cleaning middlings, rare earth secondary cleaning middlings, rare earth tertiary cleaning middlings, and rare earth quaternary cleaning middlings obtained from the rare earth flotation, and then performing niobium flotation, specifically as follows: Step (61): The rare earth roughing tailings, rare earth primary cleaning middlings, rare earth secondary cleaning middlings, rare earth tertiary cleaning middlings, and rare earth quaternary cleaning middlings obtained from the rare earth flotation are mixed and then subjected to niobium roughing to obtain niobium roughing tailings and niobium roughing concentrate. The conditions for niobium roughing are: flotation temperature 65℃, concentration 42wt%, activator (zinc nitrate and lead nitrate in a mass ratio of 1:4) dosage 1.22kg / t, inhibitor (carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate in a mass ratio of 7:1:2) dosage 0.55kg / t, collector (salicyloxyhydroxamic acid, benzoyloxyxamic acid, and 8-hydroxyquinoline in a mass ratio of 5:3:1) dosage 5.2kg / t, and frother 2# oil dosage 30g / t. Step (62): The niobium roughing concentrate is subjected to niobium primary cleaning to obtain niobium primary cleaning middlings and niobium primary cleaning concentrate; the conditions for niobium primary cleaning are: flotation temperature 65℃, concentration 42wt%, and inhibitor (mass ratio of carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate in a ratio of 7:1:2) dosage 0.82kg / t; Step (63): The niobium primary concentrate is subjected to niobium secondary concentrate to obtain niobium secondary concentrate middlings and niobium secondary concentrate; the conditions for niobium secondary concentrate are: flotation temperature 65℃, concentration 42wt%, and inhibitor (mass ratio of carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate of 7:1:2) dosage 0.55kg / t; Step (64): The niobium secondary concentrate is subjected to niobium tertiary refining to obtain niobium tertiary middlings and niobium tertiary concentrate; the conditions for niobium tertiary refining are: flotation temperature 65℃, concentration 42wt%, and inhibitor (mass ratio of carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate of 7:1:2) dosage 0.28kg / t; Step (65) involves subjecting the niobium concentrate from the third-stage niobium refining process to a fourth-stage niobium refining process, yielding middlings and concentrate. The conditions for the fourth-stage niobium refining process are: flotation temperature of 65℃, concentration of 42wt%, and inhibitor dosage (carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate in a mass ratio of 7:1:2) of 0.06 kg / t. The results of the niobium flotation are shown in Table 8.

[0084] Table 8

[0085] As shown in Table 8, after one roughing and four cleaning processes of niobium flotation, the yield of the niobium concentrate obtained after four cleaning processes was 5.06%, the Nb2O5 grade was 3.900%, and the recovery rate was 51.71%.

[0086] Step (7) involves a second weak magnetic separation of the niobium fourth-stage concentrate, with a magnetic field strength of 143.23 kA / m, yielding niobium concentrate and iron concentrate. The results of the second weak magnetic separation are shown in Table 9.

[0087] Table 9

[0088] As shown in Table 9, the niobium concentrate obtained after two weak magnetic separations can achieve a yield of 66.53%, an Nb2O5 grade of 5.37%, and a recovery rate of 91.59% after two weak magnetic separations.

[0089] The middlings from the third and fourth niobium cleaning processes were combined and returned to the niobium roughing process. After a closed-circuit test, the Nb₂O₅ grade of the niobium concentrate was 5.25%, and the recovery rate from niobium flotation to secondary weak magnetic separation was 55.25%. MLA analysis of the niobium concentrate was performed, and the results are shown in Table 10.

[0090] Table 10

[0091] As shown in Table 10, the niobium-bearing minerals in the niobium concentrate include: 0.41% columbite, 1.67% baotou ore, 26.32% calcite, 1.45% columbite-rutile, and 0.72% pyrochlore, totaling 30.57%. Calcite accounts for 86.11%, which is an increase of 44.11% compared to the 42% calcite content in the original ore.

[0092] In summary, the overall niobium recovery rate in Example 1 was 25.09%; the grade of the obtained niobium concentrate was 5.25%; and in the niobium concentrate, easily calcified niobium minerals accounted for 86.11% of the niobium-containing mineral content.

[0093] Example 2 This embodiment provides a highly efficient method for separating niobium in silicate-type low-grade niobium ore, including: Step (1): The raw ore (same as in Example 1) is ground once until the material mass ratio of the particle size less than 0.074mm is 85%. The raw ore after the first grinding is subjected to a weak magnetic separation with a magnetic field strength of 178.6kA / m to obtain iron concentrate and tailings from the first magnetic separation.

[0094] Step (2): The tailings from the primary magnetic separation are subjected to primary gravity column desliming with a feed concentration of 15wt%, a feed pump speed of 330rpm, a riser water speed of 45L / h, and a bottom flow pump speed of 45rpm to obtain slime and primary gravity desliming concentrate; the primary gravity desliming concentrate is then subjected to secondary gravity column separation with a feed concentration of 25wt%, a feed pump speed of 330rpm, a riser water speed of 45L / h, a makeup water speed of 15L / h, and a bottom flow pump speed of 35rpm to obtain light minerals and secondary gravity sediment.

[0095] Step (3): Sulfuric acid, butyl xanthate, and No. 2 oil are added to the secondary gravity separation sediment for desulfurization roughing. The feed concentration is 45.00 wt%, the amount of sulfuric acid is 0.15 kg / t, the amount of butyl xanthate is 2.5 kg / t, and the amount of No. 2 oil is 20 g / t, to obtain sulfur rough concentrate and sulfur rough tailings. The sulfur rough concentrate is then desulfurized and refined. The feed concentration is 45 wt%. No reagents are added during the desulfurization and refinement process, to obtain sulfur concentrate and sulfur middlings.

[0096] Step (4): The sulfur middlings are returned to the desulfurization roughing process for a closed-circuit test. The sulfur tailings are then subjected to secondary grinding using an ISA mill until the material mass ratio of particles smaller than 0.074 mm is 93%.

[0097] Step (5) involves rare earth flotation of the material after secondary grinding, specifically including: Step (51): Rare earth roughing is performed on the material after the secondary grinding to obtain rare earth roughing tailings and rare earth roughing concentrate; the conditions for rare earth roughing are: flotation concentration 65wt%, flotation temperature 60℃, water glass dosage 1.50kg / t, sulfuric acid 0.6kg / t, LF-P8 collector dosage 2.8kg / t, and No. 2 oil dosage 0.2kg / t. Step (52): Rare earth scavenging is performed on the rare earth roughing tailings to obtain rare earth scavenged tailings and rare earth scavenged concentrate. Rare earth scavenging conditions: flotation temperature 60℃, water glass dosage 0.4kg / t, sulfuric acid 0.1kg / t, LF-P8 collector dosage 1.2kg / t, and No. 2 oil dosage 0.15kg / t. Step (53): The rare earth roughing concentrate and the rare earth scavenging concentrate are combined and then subjected to primary rare earth refining to obtain primary rare earth middlings and primary rare earth concentrate. The conditions for primary rare earth refining are: flotation concentration 55wt%, flotation temperature 60℃, water glass dosage 0.45kg / t, sulfuric acid 0.2kg / t, LF-P8 collector dosage 2kg / t, and No. 2 oil dosage 0.25kg / t. Step (54): The rare earth primary concentrate is subjected to rare earth secondary refining to obtain rare earth secondary refining middlings and rare earth secondary refining concentrate; the conditions for rare earth secondary refining are: flotation concentration 55wt%, flotation temperature 60℃, water glass dosage 0.25kg / t, LF-P8 collector dosage 0.7kg / t, and No. 2 oil dosage 0.1kg / t. Step (55): The rare earth secondary concentrate is subjected to rare earth tertiary refining to obtain rare earth middlings and rare earth tertiary concentrate; the conditions for rare earth tertiary refining are: flotation concentration 55wt%, flotation temperature 60℃, water glass dosage 0.2kg / t, LF-P8 collector dosage 1.2kg / t, and No. 2 oil dosage 0.16kg / t. Step (56): The rare earth concentrate from the three-stage rare earth refining process is subjected to a fourth-stage rare earth refining process to obtain the rare earth middlings and the rare earth concentrate from the fourth-stage rare earth refining process. The conditions for the fourth-stage rare earth refining process are: flotation concentration 55wt%, flotation temperature 60℃, water glass dosage 0.10kg / t, LF-P8 collector dosage 0.3kg / t, and No. 2 oil dosage 0.02kg / t.

[0098] Step (6) involves mixing the rare earth scavenging tailings, rare earth primary cleaning middlings, rare earth secondary cleaning middlings, rare earth tertiary cleaning middlings, and rare earth quaternary cleaning middlings obtained from the rare earth flotation, and then performing niobium flotation, specifically as follows: Step (61): The rare earth roughing tailings, rare earth primary cleaning middlings, rare earth secondary cleaning middlings, rare earth tertiary cleaning middlings, and rare earth quaternary cleaning middlings obtained from the rare earth flotation are mixed and then subjected to niobium roughing to obtain niobium roughing tailings and niobium roughing concentrate. The conditions for niobium roughing are: flotation temperature 60℃, concentration 45wt%, activator (zinc nitrate and lead nitrate in a mass ratio of 1.5:4) dosage 1.5kg / t, inhibitor (carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate in a mass ratio of 8:1:2) dosage 0.8kg / t, collector (salicyloxyhydroxamic acid, benzoyloxyxamic acid, and 8-hydroxyquinoline in a mass ratio of 5:3:2) dosage 6kg / t, and frother 2# oil dosage 50g / t. Step (62): The niobium roughing concentrate is subjected to niobium primary cleaning to obtain niobium primary cleaning middlings and niobium primary cleaning concentrate; the conditions for niobium primary cleaning are: flotation temperature 60℃, concentration 45wt%, and inhibitor (mass ratio of carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate of 8:1:2) dosage 1kg / t; Step (63): The niobium primary concentrate is subjected to niobium secondary concentrate to obtain niobium secondary concentrate middlings and niobium secondary concentrate; the conditions for niobium secondary concentrate are: flotation temperature 60℃, concentration 45wt%, and inhibitor (mass ratio of carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate of 8:1:2) dosage 0.8kg / t; Step (64): The niobium secondary concentrate is subjected to niobium tertiary refining to obtain niobium tertiary middlings and niobium tertiary concentrate; the conditions for niobium tertiary refining are: flotation temperature 60℃, concentration 45wt%, and inhibitor (mass ratio of carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate in 8:1:2) dosage 0.5kg / t; Step (65): The niobium concentrate from the third-stage refining process is subjected to a fourth-stage refining process to obtain niobium middlings and niobium concentrate from the fourth-stage refining process. The conditions for the fourth-stage refining process are: flotation temperature of 60℃, concentration of 45wt%, and dosage of inhibitor (carboxymethyl cellulose with a degree of substitution of 0.8, aminoethyl starch, and sodium humate in a mass ratio of 8:1:2) of 0.02kg / t.

[0099] Step (7) involves a second weak magnetic separation of the niobium fourth-stage concentrate, with a magnetic field strength of 152.1 kA / m, yielding niobium concentrate and iron concentrate. The middlings from the niobium third-stage and fourth-stage concentrates are then combined and returned to the niobium roughing process for a closed-circuit test.

[0100] In Example 2, the overall niobium recovery rate was 25.17%; the grade of the obtained niobium concentrate was 5.18%; and in the niobium concentrate, easily calcified niobium minerals accounted for 84.82% of the niobium-containing mineral content.

[0101] Comparative Example 1 This comparative example provides a highly efficient separation method for niobium in silicate-type low-grade niobium ore similar to Example 1. The difference is that the order of the first weak magnetic separation and gravity column separation is reversed. That is, the raw ore after one grinding is first subjected to a gravity column desliming and a second gravity column separation, and then subjected to a weak magnetic separation. The other processes are the same as in Example 1.

[0102] The overall niobium recovery rate of Comparative Example 1 was 17.92%, which was nearly 7% lower than that of Example 1; the final niobium concentrate had a Nb2O5 grade of 5.22% and an calcite content of 82.59% in the niobium-bearing minerals.

[0103] Comparing Comparative Example 1 and Example 1, it can be seen that after changing the order of the weak magnetic separation and gravity separation columns, the niobium grade, niobium recovery rate, and the proportion of easily calcified minerals in the final niobium concentrate all decrease. The impact on the overall niobium recovery rate is particularly significant. This is because: after changing the order of the weak magnetic separation and gravity separation columns, the gravity separation column throughput becomes 1.4 times the original, resulting in a substantial increase in equipment investment. Simultaneously, the desliming volume also increases by 1.4 times, leading to a greater loss of easily calcified niobium minerals in the slime. Furthermore, after the gravity separation column, magnetite becomes enriched in the concentrate, resulting in a coarser particle size. Magnetic minerals, along with niobium minerals, are removed by magnetic separation, further increasing the loss of easily calcified minerals. Ultimately, this leads to a greater loss of easily calcified niobium minerals before entering the sulfur flotation stage, resulting in a significantly lower easily calcified niobium mineral recovery rate in the final niobium concentrate compared to Example 1.

[0104] Comparative Example 2 This comparative example provides an efficient separation method for niobium in silicate-type low-grade niobium ore similar to Example 1. The difference is that in step (4), the proportion of material with a particle size of less than 0.045 mm after secondary grinding is 95%, and the other processes are the same as in Example 1.

[0105] In Comparative Example 2, the overall niobium recovery rate was 14.88%. The final niobium concentrate had a Nb2O5 grade of 4.55%, a niobium flotation and secondary magnetic separation recovery rate of 27.86%, and a calcite content of 73.16% in the niobium-bearing minerals. Both the niobium grade and recovery rate decreased significantly, indicating that excessively fine secondary grinding particles would seriously affect the flotation efficiency of calcite, resulting in calcite loss.

[0106] Comparative Example 3 This comparative example provides a highly efficient separation method for niobium in silicate-type low-grade niobium ore similar to Example 1. The difference is that the first weak magnetic separation step is placed after the desulfurization flotation. That is, the raw ore after one grinding is first subjected to a gravity column desliming, a second gravity column separation, desulfurization roughing and desulfurization cleaning, and then subjected to a weak magnetic separation. The other processes are the same as in Example 1.

[0107] The overall niobium recovery rate of Comparative Example 3 was 13.77%; the Nb₂O₅ grade in the final niobium concentrate was 5.13%, and the proportion of easily calcite in the niobium-containing minerals was 81.81%. This comparative example has the same drawbacks as Comparative Example 1. In addition, placing magnetic separation after desulfurization flotation increases the throughput of sulfur flotation, leading to greater loss of easily calcite in the sulfur concentrate. At the same time, after sulfur flotation, magnetic iron minerals are enriched again, and during subsequent magnetic separation, niobium minerals such as easily calcite will be carried away, resulting in a significant decrease in the final niobium recovery rate.

[0108] Comparative Example 4 This comparative example provides an efficient separation method for niobium in silicate-type low-grade niobium ore similar to that in Example 1, except that the activator in the niobium flotation is lead nitrate.

[0109] The overall niobium recovery rate of Comparative Example 4 was 19.28%; the final niobium concentrate had a Nb₂O₅ grade of 5.14%, and the proportion of easily calcite in the niobium-bearing minerals was 83.22%. Although lead nitrate alone can produce qualified niobium concentrate, the recovery rate is low, indicating that the combined use of zinc nitrate and lead nitrate has a synergistic activation effect.

[0110] Comparative Example 5 This comparative example provides an efficient separation method for niobium in silicate-type low-grade niobium ore similar to that in Example 1. The difference is that, in the niobium flotation, the roughing inhibitor is ammonium fluorosilicate, and the cleaning inhibitor is oxalic acid.

[0111] The overall niobium recovery rate of Comparative Example 5 was 17.95%; the final niobium concentrate had an Nb₂O₅ grade of 3.85%, and the proportion of easily calcite in the niobium-bearing minerals was 59.23%. For the easily calcite separation of this invention, the inhibitor in this comparative example was less effective. This is because ammonium fluorosilicate and oxalic acid are effective inhibitors for separating chlorophyllite and niobite-iron rutile, and they also require the separation pH to be weakly acidic, which is unsuitable for the easily calcite separation scheme of this invention.

[0112] Comparative Example 6 This comparative example provides an efficient separation method for niobium in silicate-type low-grade niobium ore similar to that in Example 1, except that the collector used in the niobium flotation is C5-9-hydroxyoxime acid.

[0113] The overall niobium recovery rate of Comparative Example 6 was 18.77%; the final niobium concentrate had a Nb₂O₅ grade of 3.77%, and the proportion of easily calcite in the niobium-bearing minerals was 71.69%. This indicates that conventional collectors have poor selectivity for easily calcite.

[0114] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A highly efficient method for separating niobium from silicate-type low-grade niobium ore, characterized in that, The method includes the following steps: Step (1): The raw ore is ground once, and the raw ore after grinding is subjected to weak magnetic separation once to obtain iron concentrate and tailings after magnetic separation; in the raw ore, the niobium grade is 0.10%-0.15%, and easily calcified niobium minerals account for more than 40% of the volume content of niobium-containing minerals in the raw ore. Step (2): The tailings from the first magnetic separation are deslimed by a first gravity column to obtain slime and deslimed concentrate from the first gravity separation. The deslimed concentrate from the first gravity separation is then separated by a second gravity column to obtain light minerals and secondary gravity sediment. Step (3) involves desulfurizing and flotating the secondary gravity separation sediment to obtain sulfur tailings and sulfur concentrate; Step (4) involves secondary grinding of the sulfur tailings until the mass percentage of material with a particle size less than 0.074 mm is 90%-95%. Step (5) involves rare earth flotation of the material after secondary grinding, which includes rare earth roughing, rare earth scavenging, rare earth primary cleaning, rare earth secondary cleaning, rare earth tertiary cleaning and rare earth quaternary cleaning in sequence. Step (6): The rare earth tailings, middlings from the first, second, third, and fourth rare earth cleaning processes obtained from the rare earth flotation are mixed and then subjected to niobium flotation. The niobium flotation includes niobium roughing, niobium primary cleaning, niobium secondary cleaning, niobium tertiary cleaning, and niobium quaternary cleaning performed sequentially. The reagents for the niobium flotation include: activator, inhibitor, collector, and frother. The activator is a mixture of zinc nitrate and lead nitrate. The inhibitor is a mixture of carboxymethyl cellulose, aminoethyl starch, and sodium humate with a degree of substitution ≥0.

8. The collector is a mixture of salicylic acid, benzoic acid, and 8-hydroxyquinoline. The frother is terpineol. Step (7): The niobium concentrate obtained from the fourth niobium refining process is subjected to a second weak magnetic separation to obtain niobium concentrate.

2. The method according to claim 1, characterized in that, In step (1), the first grinding is to grind the raw ore until the mass ratio of the material with a particle size of less than 0.074 mm is 85%-90%.

3. The method according to claim 1, characterized in that, In step (1), the magnetic field strength of the first weak magnetic separation is 159.1-199.0 kA / m.

4. The method according to claim 1, characterized in that, In step (2), the conditions for the primary gravity column desliming include: feed concentration of 15wt%-20wt%, feed pump speed of 280-330rpm, rising water flow rate of 40-45L / h, and underflow pump speed of 40-45rpm.

5. The method according to claim 1, characterized in that, In step (2), the conditions for secondary gravity separation include: feed concentration of 25wt%-30wt%, feed pump speed of 280-330rpm, rising water flow rate of 40-45L / h, replenishment water flow rate of 10-15L / h, and underflow pump speed of 35-40rpm.

6. The method according to claim 1, characterized in that, In step (3), the desulfurization flotation includes desulfurization roughing and desulfurization cleaning; sulfuric acid, butyl xanthate and terpineol are added to the secondary gravity separation sediment for desulfurization roughing to obtain sulfur rough concentrate and sulfur rough tailings; the sulfur rough concentrate is desulfurized and cleaned to obtain sulfur concentrate and sulfur middlings, the sulfur middlings are returned to the desulfurization roughing step, and the sulfur rough tailings are entered into step (4) as sulfur tailings; And / or, the conditions for the desulfurization roughing process include: feed concentration of 45wt%-50wt%, sulfuric acid dosage of 0.1-0.15kg / t, butyl xanthate dosage of 2-2.5kg / t, and terpineol dosage of 10-30g / t; And / or, the desulfurization and beneficiation conditions include: a feed concentration of 45wt%-50wt%, with no reagents added.

7. The method according to claim 1, characterized in that, In step (5), the conditions for the rare earth roughing include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 1-1.5kg / t, pH adjuster dosage of 0.3-0.6kg / t, collector dosage of 2.2-2.8kg / t, and frother dosage of 0.1-0.2kg / t. And / or, the conditions for rare earth scavenging include: flotation temperature of 60-65℃, inhibitor dosage of 0.4-0.8 kg / t, pH adjuster dosage of 0.1-0.2 kg / t, collector dosage of 1.2-2 kg / t, and frother dosage of 0.15-0.25 kg / t.

8. The method according to claim 1, characterized in that, In step (5), the conditions for the primary rare earth refining include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.35-0.45kg / t, pH adjuster dosage of 0.1-0.2kg / t, collector dosage of 1.2-2kg / t, and frother dosage of 0.15-0.25kg / t. And / or, the conditions for the secondary rare earth refining include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.25-0.38kg / t, collector dosage of 0.7-1.3kg / t, and frother dosage of 0.1-0.2kg / t; And / or, the conditions for the three-stage rare earth refining process include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.2-0.3kg / t, collector dosage of 0.8-1.2kg / t, and frother dosage of 0.08-0.16kg / t; And / or, the conditions for the four-stage rare earth refining process include: flotation concentration of 55wt%-65wt%, flotation temperature of 60-65℃, inhibitor dosage of 0.1-0.2kg / t, collector dosage of 0.3-0.8kg / t, and frother dosage of 0.02-0.1kg / t.

9. The method according to claim 1, characterized in that, In step (6), the conditions for the roughing of niobium include: flotation concentration of 40wt%-45wt%, flotation temperature of 60-65℃, activator dosage of 1-1.5kg / t, inhibitor dosage of 0.3-0.8kg / t, collector dosage of 5-6kg / t, and frother dosage of 20-50g / t. And / or, the conditions for the primary niobium refining include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.5-1.0kg / t; And / or, the conditions for the secondary niobium refining include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.3-0.8kg / t; And / or, the conditions for the three-stage niobium refining process include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.1-0.5kg / t; And / or, the conditions for the fourth niobium refining process include: a flotation concentration of 40wt%-45wt%, a flotation temperature of 60-65℃, and an inhibitor dosage of 0.02-0.08kg / t.

10. The method according to any one of claims 1-9, characterized in that, In step (6), the mass ratio of zinc nitrate to lead nitrate in the activator is 1-1.5:4-3.5; And / or, the mass ratio of carboxymethyl cellulose, aminoethyl starch, and sodium humate in the inhibitor is 7-8:1-0.5:2-1.5; And / or, the mass ratio of salicylic acid, benzoic acid, and 8-hydroxyquinoline in the collector is 5-6:3-2:1-2.

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