Technology for reducing fluorine, potassium and sodium through combination of iron ore concentrate enhanced fine grinding and magnetic levitation

Abstract

The invention discloses a process for reducing fluorine, potassium and sodium in iron ore concentrate through combination of enhanced fine grinding and magnetic levitation. The process comprises the following steps: (a) carrying out ball milling and enhanced dissociation by using ceramic balls; (b) primary elutriation, magnetic separation and impurity removal; (c) secondary elutriation, magnetic separation and impurity removal; and (d) concentrate reverse flotation upgrading. Aiming at low-grade iron ore containing more gangue minerals such as fluorine, potassium and sodium, an existing one-roughing and four-refining stage magnetic grinding process is adopted, the beneficiation effect is poor, fluorine, potassium and sodium in concentrate exceed the standard, and subsequent smelting is affected. On the basis of existing magnetic separation, the technology for reducing fluorine, potassium and sodium through combination of iron ore concentrate reinforced fine grinding and magnetic levitation is developed, iron upgrading and fluorine, potassium and sodium removal are conducted on the iron ore concentrate, and efficient utilization of the iron ore concentrate is achieved.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology, and in particular relates to a process for strengthening fine grinding of iron concentrate and magnetic levitation combined with potassium sodium fluoride reduction. Background Technology

[0002] The Bayan Obo West Mine has iron ore reserves of over 900 million tons and is the largest iron raw material source base for Baogang. Its iron grade is low, with over 200 million tons of dolomite-type iron-bearing rocks alone. It has high contents of sulfur, fluorine, potassium, sodium, etc. Iron minerals are closely associated with fluorine-containing minerals such as fluorite / biotite / apatite / phlogopite and potassium- and sodium-containing minerals such as albite / magnesium sodium amphibole / nepheline / biotite / phlogopite. The embedded grain size is fine, making it difficult to efficiently beneficiate iron and deeply desulfurize fluorine, potassium, and sodium impurities in the Bayan Obo West Mine [1].

[0003] At present, the fluorine content in the raw ore of Baogang Barun Beneficiation Plant is between 1% and 5%, and the fluorine content in the magnetic separation iron concentrate is about 0.4% to 0.5%, while the potassium and sodium content is between 0.2% and 0.25%. The fluorine content in the magnetic separation iron concentrate not only seriously affects the quality of the iron concentrate, but also leads to low viscosity of the sintering liquid phase, resulting in a loose, porous, thin-walled structure of the sinter. Furthermore, fluorine will volatilize, causing air pollution, which directly affects the company's economic benefits and the group's environmental protection work [2]. At present, the "one roughing and four refining" stage of the magnetic grinding process of Barun Mining Company results in excessive levels of fluorine, potassium, and sodium in the iron concentrate. The existing iron concentrate upgrading process simply adopts reverse flotation, which can only increase the TFe grade of the iron concentrate to 64.76% and the F content to as high as 0.178% [3]. It is necessary to break through the existing technical bottlenecks and develop a new environmentally friendly and efficient technology for reducing fluorine, potassium, and sodium in iron concentrate to achieve efficient upgrading and impurity reduction of iron concentrate.

[0004] [1] Zhang Jian. Current status and prospect of mineral processing technology for Bayan Obo symbiotic ore [J]. Baogang Technology, 2005, (04): 1-5;

[0005] [2] Zhang Yuqi, Xu Huifeng, Wen Bolong, et al. Fluorine in the environment and its environmental effects and pollution control [J]. Journal of Agricultural Resources and Environment, 2024, 41(01):164-174. DOI:10.13254 / j.jare.2023.0073;

[0007] [3] Lei Menglin, Liu Jie, Li Jie, et al. Study on defluorination process of reverse flotation of weak magnetic separation iron concentrate in Bayan Obo [J]. Metal Mines, 2025, (10): 97-104. DOI: 10.19614 / j.cnki.jsks.202510012. Summary of the Invention

[0008] The purpose of this invention is to address the issue of poor beneficiation efficiency and excessive levels of fluorine, potassium, and sodium in the concentrate of low-grade iron ore containing abundant gangue minerals, such as fluorine, potassium, and sodium, which hinders subsequent smelting processes, when using the existing "one roughing and four cleaning" stage grinding and magnetic separation process. This invention develops a combined process of enhanced fine grinding and magnetic levitation for iron concentrate to remove fluorine, potassium, and sodium, thereby achieving efficient utilization of the iron concentrate.

[0009] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0010] This invention discloses a process for enhanced fine grinding of iron concentrate combined with magnetic levitation to reduce potassium and sodium fluoride, comprising the following steps:

[0011] (a) Enhanced dissociation by ball milling with ceramic balls: Iron concentrate with a particle size of -200 mesh of 68% to 70% is dissociated by ball milling to obtain a dissociated product with a particle size of -200 mesh of 78% to 80%.

[0012] (b) One-time washing and magnetic separation for impurity removal: The undersize material from the high-frequency screen is subjected to washing and magnetic separation process to obtain washing and magnetic separation concentrate and washing and magnetic separation tailings;

[0013] (c) Secondary washing and magnetic separation for impurity removal: The primary washing concentrate enters the secondary washing process to obtain secondary washing concentrate and tailings;

[0014] (d) Concentrate Upgrading by Reverse Flotation: The washed magnetic separation concentrate from step (c) undergoes two reverse flotation upgrades. The first flotation removes fluorine-containing gangue, yielding flotation iron concentrate and high-fluorine tailings. The iron concentrate then enters the second flotation to remove potassium and sodium, yielding iron concentrate and high-potassium and sodium tailings. The second flotation concentrate serves as the final iron concentrate. The fluorine-rich tailings, potassium-rich and sodium-rich tailings, and the washed magnetic separation tailings from step (b) and the second washed magnetic separation tailings from step (c) are combined and discarded.

[0015] Furthermore, in step (a), the diameter of the ceramic ball is 10-20 mm, and the grinding time is 3-5 min.

[0016] Furthermore, in step (b), the washing and magnetic separation water flow rate is 1000-1600 L / h, the bottom valve opening is 40%-50%, the fixed magnetic field current is 0.5 A-1.1 A, the circulating magnetic field current is 0.5 A-1.1 A, and the compensation magnetic field current is 0.5 A-1.1 A.

[0017] Furthermore, in step (c), the washing and magnetic separation water flow rate is 1000-1600 L / h, the bottom valve opening is 40%-50%, the fixed magnetic field current is 0.5 A-1.1 A, the circulating magnetic field current is 0.5 A-1.1 A, and the compensation magnetic field current is 0.5 A-1.1 A.

[0018] Furthermore, in step (d), the amount of sodium carbonate as the primary flotation modifier is 2 kg / t, the amount of soluble starch as the inhibitor is 0.5 kg / t, the amount of sodium oleate anionic collector is 0.5–1.0 kg / t, the amount of sodium carbonate as the secondary flotation modifier is 2 kg / t, the amount of soluble starch as the inhibitor is 0.5 kg / t, and the amount of dodecylamine cationic collector is 0.05–0.15 kg / t.

[0019] Furthermore, the specific parameters in step (b) are as follows: fixed magnetic field current is 0.5 A, circulating magnetic field current is 0.5 A, compensation magnetic field current is 0.5 A, rising water volume is 1600 L / h, and bottom valve opening is 45%.

[0020] Furthermore, the specific parameters in step (C) are as follows: fixed magnetic field current is 0.6 A, circulating magnetic field current is 0.6 A, compensation magnetic field current is 0.6 A, rising water volume is 1600 L / h, and bottom valve opening is 45%.

[0021] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0022] (1) Pre-ceramic ball milling of iron concentrate effectively reduces the impact of the co-occurrence of fluorine, potassium, sodium and iron minerals on the washing, magnetic separation and reverse flotation upgrading. The inventors of this application have found that, compared with ordinary iron ball milling, ceramic ball milling does not cause iron elements to contaminate the mineral surface during the grinding process, thus improving the efficiency of washing, magnetic separation and reverse flotation.

[0023] (2) Studies have shown that fluorine-, potassium-, and sodium-containing gangue minerals have a certain degree of weak magnetism. Therefore, weak magnetic separation can be used to separate strongly magnetic iron ore from weakly magnetic gangue minerals. Panning magnetic separation has high-speed turbulence and a fine magnetic field gradient. The high-speed turbulence can fully separate iron minerals from gangue minerals, and the fine magnetic field gradient can selectively adsorb iron concentrate, thereby achieving effective separation of iron concentrate from fluorine-, potassium-, and sodium-containing gangue minerals.

[0024] (3) The high-efficiency collector for reverse flotation effectively reduces the levels of fluorine, potassium, and sodium minerals in iron concentrate. Through long-term research, the inventors of this application discovered that only by first adjusting the pH with a pH adjuster, then adding a starch-based inhibitor to suppress magnetite, and finally adding the collector, can magnetite be suppressed while fluorite and biotite are simultaneously floated out, thus achieving effective separation of fluorine, potassium, and sodium minerals. Starch-based reagents preferentially adsorb onto the iron-active sites on the surface of magnetite, inhibiting its hydrophilicity, while essentially not adsorbing onto the surfaces of fluorite and biotite. This reagent addition sequence eliminates the need for additional complex equipment and operating procedures, reducing production costs and operational difficulty.

[0025] (4) The process of this invention is simple, the purification effect is significant, and the fluorine, potassium and sodium minerals in the concentrate are fully removed. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings.

[0027] Figure 1 This is a flowchart of the present invention;

[0028] Figure 2 This is a flowchart of Example 1;

[0029] Figure 3 The flowchart is for Comparative Example 1;

[0030] Figure 4 The flowchart is for Comparative Example 2. Detailed Implementation

[0031] like Figure 1 As shown, a process for strengthening fine grinding of iron concentrate and magnetic levitation combined with potassium and sodium fluoride reduction specifically includes the following steps:

[0032] (a) Enhanced dissociation by ceramic ball milling: Iron concentrate 1 with a particle size of -200 mesh of 68% to 70% is dissociated by ball milling A to obtain dissociated product 2 with a particle size of -200 mesh of 78% to 80%.

[0033] The ceramic balls have a diameter of 10–20 mm, and the grinding time is 3–5 min.

[0034] (b) One-time washing and magnetic separation to remove impurities; the undersize material from high frequency screen B is processed by washing and magnetic separation C to obtain washing and magnetic separation concentrate 5 (target mineral) and washing and magnetic separation tailings 6 (fluorine-rich, potassium- and sodium-rich products).

[0035] The washing and magnetic separation water flow rate is 1000-1600 L / h, the bottom valve opening is 40%-50%, the fixed magnetic field current is 0.5 A-1.1 A, the circulating magnetic field current is 0.5 A-1.1 A, and the compensation magnetic field current is 0.5 A-1.1 A.

[0036] (c) Secondary washing and magnetic separation to remove impurities; the first-stage washed concentrate 5 enters the secondary washing process D to obtain the secondary washed magnetic separation concentrate 7 (target mineral) and tailings 8 (fluorine-rich, potassium- and sodium-rich products).

[0037] The washing and magnetic separation water flow rate is 1000-1600 L / h, the bottom valve opening is 40%-50%, the fixed magnetic field current is 0.5 A-1.1 A, the circulating magnetic field current is 0.5 A-1.1 A, and the compensation magnetic field current is 0.5 A-1.1 A.

[0038] (d) Concentrate Reverse Flotation Upgrading: The washed magnetic separation concentrate 7 in step c undergoes two reverse flotation upgrades. The first flotation E removes fluorine-containing gangue, yielding flotation iron concentrate 9 and high-fluorine tailings 10. Iron concentrate 9 enters the second flotation F to remove potassium and sodium, yielding iron concentrate 11 and high-potassium and sodium tailings 12. The second flotation concentrate 11 serves as the final iron concentrate. The fluorine-rich tailings 10, potassium-rich and sodium-rich tailings 12, and the washed magnetic separation tailings 6 from step b and the second washed magnetic separation tailings 8 from step c are combined and discarded.

[0039] The dosage of sodium carbonate as a modifier in the primary flotation is 2 kg / t, the dosage of soluble starch as a depressant is 0.5 kg / t, and the dosage of sodium oleate anionic collector is 0.5–1.0 kg / t. The dosage of sodium carbonate as a modifier in the secondary flotation is 2 kg / t, the dosage of soluble starch as a depressant is 0.5 kg / t, and the dosage of dodecylamine cationic collector is 0.05–0.15 kg / t.

[0040] Example 1

[0041] This embodiment provides a process for enhanced fine grinding of iron concentrate combined with magnetic levitation to reduce potassium and sodium fluoride levels. The process flow diagram is as follows: Figure 2 As shown, the specific operation is as follows:

[0042] (1) Grind the minerals using a ceramic ball mill with a ceramic ball ratio of Φ20mm:Φ15mm:Φ10mm and a mass ratio of 1:1:1 to obtain a material product with a mineral particle size of -74 μm accounting for 79.36%; add water to the material product to adjust the slurry concentration to 35%.

[0043] (2) The slurry obtained in step (1) is fed into a first-stage washing magnetic separator. The equipment parameters are: fixed magnetic field current is 0.5A, circulating magnetic field current is 0.5A, compensation magnetic field current is 0.5A, rising water volume is 1600 L / h, bottom valve opening is 45%, and the washing magnetic separator produces washing magnetic concentrate 1.

[0044] (3) The washed magnetic concentrate 1 obtained in step (2) is fed into the second-stage washing magnetic separator. The equipment parameters are: fixed magnetic field current is 0.6 A, circulating magnetic field current is 0.6 A, compensation magnetic field current is 0.6 A, rising water volume is 1600 L / h, bottom valve opening is 45%, and the washed magnetic concentrate 2 is obtained.

[0045] (4) Add sodium carbonate (dosage shown in Table 1) as a pH adjuster to the washed magnetic separation concentrate 2 obtained in step (3) and stir for 2 minutes to adjust the pH of the slurry to 8.2; add soluble starch (dosage shown in Table 1) as an inhibitor and stir for 2 minutes; add sodium oleate (dosage shown in Table 1) as a collector and stir for 2 minutes; then start aeration and skim bubbles for 2 minutes to finally obtain iron concentrate 3.

[0046] (5) Add sodium carbonate (dosage shown in Table 1) as a pH adjuster to the iron concentrate 3 obtained in step (4) and stir for 2 minutes to adjust the pH of the slurry to 8.2; add soluble starch (dosage shown in Table 1) as an inhibitor and stir for 2 minutes; add dodecylamine (dosage shown in Table 1) as a collector and stir for 2 minutes; then start aeration and skim the bubbles for 2 minutes to finally obtain iron concentrate 4.

[0047] Through the enhanced fine grinding-magnetic levitation combined process of iron concentrate and potassium sodium defluorination in this embodiment, the iron concentrate is upgraded to an iron concentrate with elemental content of 70.01% TFe, 0.09% F, and 0.142% K+ Na; the Fe recovery rate can reach 95.79%, the F content is reduced by 72.72%, and the K2O and Na2O contents are reduced by a total of 55.52%.

[0048] Comparative Example 1

[0049] A comparative example provides a process for strengthening the fine grinding of iron concentrate and flotation to reduce fluoride using potassium sodium, as shown in the process flow diagram below. Figure 3 As shown, the specific operation is as follows:

[0050] (1) Grinding was performed using a ceramic ball mill with a ceramic ball ratio of Φ20mm:Φ15mm:Φ10mm and a mass ratio of 1:1:1 to obtain a material product with a mineral particle size of -74 μm accounting for 79.36%; water was added to the material product to adjust the slurry concentration to 35%;

[0051] (2) Add sodium carbonate (dosage shown in Table 1) as a pH adjuster to the slurry obtained in step (1) and stir for 2 minutes to adjust the pH of the slurry to 8.2; add soluble starch (dosage shown in Table 1) as an inhibitor and stir for 2 minutes; add sodium oleate (dosage shown in Table 1) as a collector and stir for 2 minutes; then start aeration and skim the bubbles for 2 minutes to finally obtain iron concentrate 1.

[0052] (3) Add sodium carbonate (dosage shown in Table 1) as a pH adjuster to the iron concentrate 1 obtained in step (2) and stir for 2 minutes to adjust the pH of the slurry to 8.2; add soluble starch (dosage shown in Table 1) as an inhibitor and stir for 2 minutes; add dodecylamine (dosage shown in Table 1) as a collector and stir for 2 minutes; then start aeration and skim the bubbles for 2 minutes to finally obtain iron concentrate 2.

[0053] Through the comparative iron concentrate enhanced fine grinding-flotation process to reduce fluoride content with potassium sodium, the iron concentrate was upgraded to an iron concentrate with elemental content of 67.05% TFe, 0.16% F, and 0.173% K+ Na; the Fe recovery rate reached 92.55%, the F content was reduced by 70.34%, and the K2O and Na2O contents were reduced by a total of 46.37%.

[0054] Comparative Example 2

[0055] A comparative example provides a process for strengthening the fine grinding, washing, magnetic separation, and reducing fluoride and potassium sodium in iron concentrate. The process flow diagram is shown below. Figure 4 As shown, the specific operation is as follows:

[0056] (1) Grinding was performed using a ceramic ball mill with a ceramic ball ratio of Φ20mm:Φ15mm:Φ10mm and a mass ratio of 1:1:1 to obtain a material product with a mineral particle size of -74 μm accounting for 79.36%; water was added to the material product to adjust the slurry concentration to 35%;

[0057] (2) The slurry obtained in step (1) is fed into a first-stage washing magnetic separator. The equipment parameters are: fixed magnetic field current is 0.5A, circulating magnetic field current is 0.5A, compensation magnetic field current is 0.5A, rising water volume is 1600 L / h, bottom valve opening is 45%, and the washing magnetic separator produces washing magnetic concentrate 1.

[0058] (3) The washed magnetic concentrate 1 obtained in step (2) is fed into the second-stage washing magnetic separator. The equipment parameters are: fixed magnetic field current is 0.6 A, circulating magnetic field current is 0.6 A, compensation magnetic field current is 0.6 A, rising water volume is 1600 L / h, bottom valve opening is 45%, and the washed magnetic concentrate 2 is obtained.

[0059] Through the comparative iron concentrate enhanced fine grinding-flotation process to reduce fluoride content with potassium sodium, the iron concentrate was upgraded to an iron concentrate with elemental content of 70.93% TFe, 0.16% F, and 0.143% K+ Na; the Fe recovery rate reached 92.65%, the F content was reduced by 67.22%, and the K2O and Na2O contents were reduced by a total of 57.01%.

[0060] Table 1 - Specific reagent dosages in the reverse flotation process of the examples and comparative examples.

[0061]

[0062] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A process for enhanced fine grinding of iron concentrate combined with magnetic levitation to reduce potassium and sodium fluoride, characterized in that: Includes the following steps: (a) Enhanced dissociation by ball milling with ceramic balls: Iron concentrate with a particle size of -200 mesh of 68% to 70% is dissociated by ball milling to obtain a dissociated product with a particle size of -200 mesh of 78% to 80%. (b) One-time washing and magnetic separation for impurity removal: The undersize material from the high-frequency screen is subjected to washing and magnetic separation process to obtain washing and magnetic separation concentrate and washing and magnetic separation tailings; (c) Secondary washing and magnetic separation for impurity removal: The primary washing concentrate enters the secondary washing process to obtain secondary washing concentrate and tailings; (d) Concentrate Reverse Flotation Upgrading: The washed magnetic separation concentrate in step (c) undergoes two reverse flotation upgrades. The first flotation removes fluorine-containing gangue, yielding flotation iron concentrate and high-fluorine tailings. The iron concentrate enters the second flotation to remove potassium and sodium, yielding iron concentrate and high-potassium and sodium tailings. The second flotation concentrate serves as the final iron concentrate. The fluorine-rich tailings, potassium-rich and sodium-rich tailings, and the washed magnetic separation tailings from step (b) and the second washed magnetic separation tailings from step (c) are combined and discarded.

2. The process for enhanced fine grinding of iron concentrate combined with magnetic levitation to reduce potassium and sodium fluoride, as described in claim 1, is characterized in that: In step (a), the diameter of the ceramic ball is 10-20 mm, and the grinding time is 3-5 min.

3. The process for enhanced fine grinding and magnetic levitation combined with potassium and sodium fluoride reduction of iron concentrate according to claim 1, characterized in that: In step (b), the washing and magnetic separation water flow rate is 1000-1600 L / h, the bottom valve opening is 40%-50%, the fixed magnetic field current is 0.5 A-1.1 A, the circulating magnetic field current is 0.5 A-1.1 A, and the compensation magnetic field current is 0.5 A-1.1 A.

4. The process for enhanced fine grinding and magnetic levitation combined with potassium and sodium fluoride reduction of iron concentrate according to claim 1, characterized in that: In step (c), the washing and magnetic separation water flow rate is 1000-1600 L / h, the bottom valve opening is 40%-50%, the fixed magnetic field current is 0.5 A-1.1 A, the circulating magnetic field current is 0.5 A-1.1 A, and the compensation magnetic field current is 0.5 A-1.1 A.

5. The process for enhanced fine grinding and magnetic levitation combined with potassium and sodium fluoride reduction of iron concentrate according to claim 1, characterized in that: In step (d), the dosage of sodium carbonate as the primary flotation modifier is 2 kg / t, the dosage of soluble starch as the inhibitor is 0.5 kg / t, the dosage of sodium oleate anionic collector is 0.5–1.0 kg / t, the dosage of sodium carbonate as the secondary flotation modifier is 2 kg / t, the dosage of soluble starch as the inhibitor is 0.5 kg / t, and the dosage of dodecylamine cationic collector is 0.05–0.15 kg / t.

6. The process for enhanced fine grinding and magnetic levitation combined with potassium and sodium fluoride reduction of iron concentrate according to claim 4, characterized in that: The specific parameters in step (b) are: fixed magnetic field current is 0.5 A, circulating magnetic field current is 0.5 A, compensation magnetic field current is 0.5 A, rising water volume is 1600 L / h, and bottom valve opening is 45%.

7. The process for enhanced fine grinding and magnetic levitation combined with potassium and sodium fluoride reduction of iron concentrate according to claim 1, characterized in that: The specific parameters in step (C) are as follows: fixed magnetic field current is 0.6 A, circulating magnetic field current is 0.6 A, compensation magnetic field current is 0.6 A, rising water volume is 1600 L / h, and bottom valve opening is 45%.

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