Method for recovering lepidolite by composite magnetization magnetic separation

Abstract

The application discloses a method for recovering lepidolite by composite magnetization magnetic separation. The method comprises the following steps: mixing and ball-milling raw ore containing lepidolite and an activator containing iron powder, a sulfate and ferroferric oxide, dispersing the obtained ball-milling product in a solvent to form a slurry, performing superconducting low-intensity magnetic separation on the slurry to obtain an iron-removed slurry, and performing superconducting high-intensity magnetic separation on the iron-removed slurry to obtain magnetized lepidolite. The method greatly improves the surface activity of lepidolite through the synergistic effect of high-energy ball-milling mechanical energization and activator chemical energization. Furthermore, the method uses a multi-stage composite magnetization magnetic separation process of surface magnetization-low-intensity magnetic separation-high-intensity magnetic separation, thereby greatly improving the concentrate grade while improving the recovery rate of lepidolite. The method is simple in process, low in equipment investment, and suitable for industrial production and application.

Description

Technical Field

[0001] This invention relates to a method for recovering mica ore, specifically a method for recovering lithium mica by composite magnetization and magnetic separation, belonging to the field of lithium ore beneficiation technology. Background Technology

[0002] Lithium possesses excellent physical and chemical properties and is widely used in new energy, pharmaceutical, nuclear, and emerging functional metal materials industries, making it an important strategic mineral resource. With the rapid development of new materials and new energy industries both domestically and internationally, the demand for lithium is increasing dramatically. Therefore, how to efficiently and cost-effectively develop lithium resources has become an urgent problem to be solved.

[0003] In nature, lithium exists primarily as lithium from salt lakes and lithium from ores. Lithium extraction from salt lakes suffers from drawbacks such as difficulty in separating magnesium and lithium, low lithium content, and long extraction cycles. Currently, my country's industrial lithium supply still mainly relies on ores (spodumene, lepidolite). Domestic lepidolite resources are mainly distributed in Yichun, Jiangxi; Zhengchong and Jianfengling, Hunan; and Limu, Guangxi. Currently, flotation is the primary method for utilizing lepidolite mineral resources. Lepidolite is brittle and produces a large amount of fine mud during liberation. This fine mud coats the mineral surface during flotation, consuming significant amounts of flotation reagents, deteriorating the flotation pulp environment, and affecting the separation efficiency of lepidolite. Therefore, desliming is usually prioritized during lepidolite flotation. This fine mud is difficult to recover through flotation and is typically discharged directly into tailings ponds, resulting in a significant waste of lepidolite resources. Lithium mica slime readily aggregates non-selectively with gangue minerals, covering valuable minerals and reducing their interaction with flotation reagents. Simultaneously, its small particle size and increased specific surface area reduce the differences in particle movement, making mechanical entrainment more likely. This significantly increases the difficulty of separating fine slime, making the efficient recovery and utilization of micro-fine lepidolite slime resources a pressing problem. Solving the recovery problem of lepidolite slime under traditional flotation systems is extremely challenging. Overcoming the limitations of traditional flotation concepts and developing novel separation technologies is key to achieving the comprehensive utilization of lepidolite slime resources. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention provides a method for separating and recovering lepidolite using composite magnetization and magnetic separation. This method significantly improves the surface activity of lepidolite through the synergistic effect of high-energy ball milling mechanical empowerment and activator chemical empowerment. Furthermore, by utilizing a multi-stage composite magnetization and magnetic separation process involving surface magnetization, weak magnetic separation, and strong magnetic separation, the recovery rate of lepidolite is improved while the grade of the concentrate is also significantly increased. This method is simple in process, requires low equipment investment, and is suitable for industrial production and application.

[0005] To achieve the above-mentioned technical objectives, the present invention provides a method for separating and recovering lepidolite by composite magnetization and magnetic separation. The ore containing lepidolite is mixed with an activator containing iron powder, sulfate and iron(III) oxide and ball-milled. The ball-milled product is dispersed in a solvent to form a slurry. The slurry is then subjected to superconducting weak magnetic separation to obtain an iron-removed slurry. The iron-removed slurry is then subjected to superconducting strong magnetic separation to obtain magnetized lepidolite.

[0006] The method provided by this invention uses high-energy ball milling to input mechanical force, activates the lepidolite lattice with sulfate, and activates the lepidolite surface into an amorphous state. Through mechanochemical means, the lepidolite surface is induced to react with an external iron source, magnetizing the lepidolite surface and transforming the non-magnetic lepidolite into weakly magnetic lithium iron magnesia, which can then be separated and recovered by superconducting magnetic separation. Based on the method provided by this invention, the welfare recovery of lepidolite can effectively solve problems such as low lepidolite recovery rate and difficulty in recovering fine sludge.

[0007] As a preferred embodiment, the particle size of the lithium-containing mica ore does not exceed 1 mm.

[0008] As a preferred embodiment, the mass ratio of iron powder, sulfate and iron(III) oxide is 1-2.5:1-5:0.5-3.5.

[0009] As a preferred embodiment, the amount of the activator is 2.5 to 11 wt% of the raw ore containing lepidolite.

[0010] As a preferred embodiment, the sulfate includes at least one of sodium sulfate, potassium sulfate, and calcium sulfate.

[0011] As a preferred embodiment, the ball milling conditions are as follows: the grinding balls are zirconia balls, the ball milling speed is 400-600 r / min, and the ball milling time is 20-50 min.

[0012] As a preferred embodiment, the zirconia spheres comprise 60-80 zirconia spheres with a particle size of 4 mm, 20-40 zirconia spheres with a particle size of 6 mm, and 10-25 zirconia spheres with a particle size of 10 mm.

[0013] As a preferred embodiment, the solvent is water.

[0014] As a preferred embodiment, the slurry has a mass concentration of 5-30%.

[0015] As a preferred embodiment, the conditions for the superconducting weak magnetic separation are: magnetic field strength of 0.1 to 0.3 T and slurry flow rate of 5 to 20 cm / s.

[0016] As a preferred embodiment, the mass concentration of the iron ore slurry is 5-20%.

[0017] As a preferred embodiment, the conditions for the superconducting high magnetic separation are: a magnetic field strength of 4 to 7 T and a flow rate of 3 to 15 cm / s for the iron ore slurry.

[0018] As a preferred embodiment, sodium hexametaphosphate is added as a dispersant during the superconducting weak magnetic separation and superconducting strong magnetic separation processes, and the amount of dispersant is 0.2 to 0.3 wt‰ of the slurry or iron removal slurry.

[0019] As a preferred embodiment, the magnetic medium in the superconducting weak magnetic separation and superconducting strong magnetic separation processes comprises bristles with a length of 0.05–0.5 mm and / or square steel mesh with an aperture of (1–3)*(4–8) mm. The magnetic medium can also be a combination of various different types of media.

[0020] As a preferred embodiment, the superconducting magnetic separator used in the superconducting weak magnetic separation and superconducting strong magnetic separation processes is a high-gradient superconducting magnetic separator.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) In the method provided by the present invention, the surface of non-magnetic lepidolite minerals is magnetized by means of high-energy ball milling, external mechanical force and activator activation, so that they can be separated and recovered by superconducting magnetic separation, thereby improving the recovery efficiency of lepidolite.

[0023] (2) In the technical solution provided by the present invention, lepidolite is separated from muscovite, sericite and other similar materials by magnetizing the surface of the raw ore containing lepidolite, thereby achieving selective separation of lepidolite and improving the grade of lepidolite concentrate.

[0024] (3) The method provided by the present invention has the advantages of simple process, strong adaptability and no influence of ore slime, which can effectively recover fine lepidolite and greatly improve the comprehensive recovery rate of lepidolite. Compared with conventional lepidolite flotation recovery, this method can also greatly reduce the use of flotation reagents, reduce costs and increase efficiency and is environmentally friendly. Attached Figure Description

[0025] Figure 1 The present invention provides a process flow diagram for a method of separating and recovering lithium mica using composite magnetization and magnetic separation. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in further detail and completely below with reference to the accompanying drawings and embodiments. Of course, the following embodiments are for further illustration of the invention and are not intended to limit the scope of protection of the claims of this invention.

[0027] Example 1

[0028] The test ore sample was taken from a fluorite tailings mine in Chenzhou. The original ore had a particle size of -0.038mm, accounting for 92%, and contained 0.7-0.8% Li2O. The main minerals were lepidolite, muscovite, and quartz. Conventional flotation could not effectively recover lepidolite.

[0029] The specific separation and recycling steps are as follows:

[0030] (1) Weigh 100g of raw ore, 2.5g of iron powder, 2.0g of iron(III) oxide and 3.2g of potassium sulfate, put them into the grinding jar of a high-energy ball mill, and add 60 4mm zirconia balls, 10 6mm zirconia balls and 4 10mm zirconia balls;

[0031] (2) Set the high-energy ball mill speed to 500 r / min and the grinding time to 20 min;

[0032] (3) Take out the ground ore sample, add water to prepare a slurry with a mass concentration of 20%, and add 250g / t sodium hexametaphosphate according to the original ore mass, and carry out superconducting weak magnetic separation to obtain weak magnetic separation tailings slurry. The weak magnetic separation medium is 0.02mm bristles, and the slurry flow rate is 15cm / s.

[0033] (4) The concentration of the tailings slurry in the weak magnetic separation is controlled at 15%. Superconducting strong magnetic separation is carried out under the condition of magnetic field strength of 5T. The magnetic medium is a 4*6mm square steel mesh and the slurry flow rate is 5cm / s to obtain strong magnetic separation concentrate and tailings.

[0034] The superconducting magnetic separation product was analyzed to detect the Li2O content. Specific test results are shown in Table 1. Table 1: Test Results of Example 1

[0035] Product Name Yield / % <![CDATA[Li2O grade / %]]> <![CDATA[Li2O recovery rate / %]]> Lithium mica concentrate 26.35 2.19 75.93 Weak magnetic concentrate 5.74 0.36 2.72 Strong magnetic separation of tailings 67.91 0.24 21.35 Mineral feed 100 0.76 100

[0036] As can be seen from Table 1, for a certain fluorite tailings in Chenzhou, the superconducting method of recovering lepidolite after mica magnetization can obtain lepidolite concentrate with a Li2O grade of 2.19% and a recovery rate of 75.93%, which effectively realizes the recovery and utilization of lithium in the tailings.

[0037] Example 2

[0038] The test ore sample was taken from a granite porphyry lithium ore beneficiation plant in Chenzhou. The raw ore had a Li₂O content of 0.4-0.5%, and the main minerals were lepidolite, nacreous mica, muscovite, corundum, and quartz. The raw ore had a high mica content, and various types of mica easily entered the concentrate during flotation, making it difficult to obtain high-grade lithium concentrate.

[0039] The specific separation and recycling steps are as follows:

[0040] (1) The raw ore is crushed, and the particle size of the crushed raw ore is less than 1 mm.

[0041] (2) Weigh 100g of raw ore, 2.2g of iron powder, 2.5g of iron oxide, 2.0g of potassium sulfate, 1g of sodium sulfate and 1.5g of calcium sulfate, mix them well and put them into the grinding jar of a high-energy ball mill, and add 50 4mm zirconia balls, 15 6mm zirconia balls and 8 10mm zirconia balls.

[0042] (3) Set the high-energy ball mill speed to 550 r / min and the grinding time to 35 min;

[0043] (4) Take out the ground ore sample, add water to prepare a slurry with a mass concentration of 20%, and add 200g / t sodium hexametaphosphate according to the original ore mass, and carry out superconducting weak magnetic separation to obtain weak magnetic separation tailings slurry. The weak magnetic separation medium is 0.02mm bristles, and the slurry flow rate is set to 15cm / s.

[0044] (5) The concentration of the tailings slurry in the weak magnetic separation is controlled at 12%. Superconducting strong magnetic separation is carried out under the condition of magnetic field strength of 6T. The magnetic medium is a 2*4mm square steel mesh and the slurry flow rate is 15cm / s to obtain strong magnetic separation concentrate and tailings.

[0045] The superconducting magnetic separation product was analyzed to detect the Li2O content. Specific test results are shown in Table 2. Table 2: Test Results of Example 2

[0046] Product Name Yield / % <![CDATA[Li2O grade / %]]> <![CDATA[Li2O recovery rate / %]]> Lithium mica concentrate 16.10 1.86 74.39 Weak magnetic concentrate 6.04 0.18 2.40 Strong magnetic separation of tailings 77.86 0.12 23.21 Mineral feed 100 0.40 100

[0047] As can be seen from Table 2, the method of recovering lepidolite by superconducting magnetic separation after mica surface magnetization increases the lithium oxide grade in the concentrate to 1.86%, which achieves better recovery and utilization of lepidolite.

[0048] Example 3

[0049] The test ore sample was taken from the tailings of a lepidolite beneficiation plant in Jiangxi Province. The original ore had a particle size of -0.038 mm, accounting for 80%, and contained 0.25% Li2O. The main minerals were lepidolite, lepidolite, potassium feldspar, and quartz. Due to the fine particle size and low lithium content of the original ore, it was difficult to effectively recover the lithium through flotation.

[0050] The specific separation and recycling steps are as follows:

[0051] (1) Weigh 100g of raw ore, 1.5g of iron powder, 3g of iron oxide, 2.5g of calcium sulfate, and 2.0g of potassium sulfate, put them into the grinding jar of a high-energy ball mill, and add 60 4mm zirconia balls, 10 6mm zirconia balls, and 5 10mm zirconia balls.

[0052] (2) Set the high-energy ball mill speed to 4800 r / min and the grinding time to 25 min;

[0053] (3) Take out the ground ore sample, add water to prepare a slurry with a mass concentration of 20%, and add 200g / t sodium hexametaphosphate according to the original ore mass, and carry out superconducting weak magnetic separation to obtain weak magnetic separation tailings slurry. The weak magnetic separation medium is 0.02mm bristles, and the slurry flow rate is set to 15cm / s.

[0054] (4) The concentration of the tailings slurry in the weak magnetic separation is controlled at 15%. Superconducting strong magnetic separation is carried out under the condition of magnetic field strength of 7T. The magnetic medium is a 4*6mm square steel mesh and the slurry flow rate is 10cm / s to obtain strong magnetic separation concentrate and tailings.

[0055] The superconducting magnetic separation product was tested and analyzed to detect the Li2O content. The specific test results are shown in Table 3.

[0056] Table 3. Experimental Results of Example 3

[0057] Product Name Yield / % <![CDATA[Li2O grade / %]]> <![CDATA[Li2O recovery rate / %]]> Lithium mica concentrate 10.65 1.56 66.46 Weak magnetic concentrate 5.79 0.13 3.01 Strong magnetic separation of tailings 83.56 0.09 30.53 Mineral feed 100.00 0.25 100.00

[0058] As can be seen from Table 3, the method of recovering lepidolite by superconducting magnetic separation after mica surface magnetization also has a good recovery effect on low-grade lepidolite. When the raw ore has a Li2O grade of 0.25%, lepidolite concentrate with Li2O grade and recovery rate of 1.56% and 66.46% can still be obtained.

[0059] The above embodiments demonstrate that the new method for recovering lithium mica by superconducting magnetic separation after mica surface magnetization has the advantages of wide adaptability and high separation efficiency.

[0060] To further illustrate the technical advantages of the present invention, comparative examples 1 to 4 were conducted based on example 3.

[0061] Comparative Example 1

[0062] The process of this comparative example is exactly the same as that of Example 3, except that: the lepidolite ore is not subjected to surface magnetization treatment, and the ore is directly prepared into a slurry with a mass concentration of 15%, and then superconducting magnetic separation is performed. The magnetic separation process and parameters are consistent with those of Example 3.

[0063] Comparative Example 2

[0064] The process of this comparative example is exactly the same as that of Example 3. The difference is that when the lepidolite ore is surface magnetized, only 1.5g of iron powder and 3g of iron oxide are added, and no sulfate activator is added for grinding. Other experimental procedures and parameters are consistent with those of Example 3.

[0065] Comparative Example 3

[0066] The comparative example is exactly the same as the process in Example 3, except that when the lithium mica ore is surface magnetized, only 2.5g of calcium sulfate and 2.0g of potassium sulfate are added, and iron powder and iron oxide are not added for grinding. Other experimental procedures and parameters are consistent with those in Example 3.

[0067] Comparative Example 4

[0068] The process of this comparative example is exactly the same as that of Example 3, except that the high-energy ball milling time is reduced to 10 minutes when the lepidolite raw ore is surface magnetized. Other experimental procedures and parameters are consistent with those of Example 3.

[0069] The experimental results of each comparative example are shown in Table 4. It can be seen from the experimental structures of each comparative example that the experimental indicators of each embodiment are significantly lower than those of Comparative Example 3. This indicates that the new method for recovering lithium mica by superconducting magnetic separation after mica surface magnetization provided by this invention has a reasonable process flow, and each step is indispensable.

[0070] Table 4

[0071] product Yield / % <![CDATA[Li2O grade / %]]> <![CDATA[Li2O recovery rate / %]]> Example 3 Lithium mica concentrate 10.65 1.56 66.46 Comparative Example 1 Lithium mica concentrate 0.85 1.01 3.74 Comparative Example 2 Lithium mica concentrate 2.28 0.89 8.12 Comparative Example 3 Lithium mica concentrate 0.91 1.21 4.4 Comparative Example 4 Lithium mica concentrate 5.73 1.51 34.6

Claims

1. A method for separating and recovering lepidolite using composite magnetization and magnetic separation, characterized in that: The raw ore containing lithium mica is mixed with an activator containing iron powder, sulfate and iron oxide and ball-milled. The ball-milled product is dispersed in a solvent to form a slurry. The slurry is then subjected to superconducting weak magnetic separation to obtain an iron-removed slurry. The iron-removed slurry is then subjected to superconducting strong magnetic separation to obtain magnetized lithium mica.

2. The method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1, characterized in that: The mass ratio of iron powder, sulfate, and iron(III) oxide is 1–2.5:1–5:0.5–3.5; The amount of the activator used is 2.5 to 11 wt% of the raw ore containing lepidolite.

3. A method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1 or 2, characterized in that: The sulfate includes at least one of sodium sulfate, potassium sulfate, and calcium sulfate.

4. A method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1 or 2, characterized in that: The ball milling conditions are as follows: the grinding balls are zirconia balls, the ball milling speed is 400-600 r / min, and the ball milling time is 20-50 min.

5. The method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 4, characterized in that: The zirconia spheres comprise 60-80 zirconia spheres with a particle size of 4 mm, 20-40 zirconia spheres with a particle size of 6 mm, and 10-25 zirconia spheres with a particle size of 10 mm.

6. The method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1, characterized in that: The slurry has a mass concentration of 5-30%.

7. A method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1 or 6, characterized in that: The conditions for superconducting weak magnetic separation are: magnetic field strength of 0.1 to 0.3 T and slurry flow rate of 5 to 20 cm / s.

8. The method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1, characterized in that: The mass concentration of the iron removal slurry is 5-20%.

9. A method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1 or 8, characterized in that: The conditions for superconducting high magnetic separation are: magnetic field strength of 4-7T and iron ore slurry flow rate of 3-15cm / s.

10. The method for separating and recovering lepidolite using composite magnetization and magnetic separation according to claim 1, characterized in that... The characteristic is that sodium hexametaphosphate is added as a dispersant during the superconducting weak magnetic separation and superconducting strong magnetic separation processes. The amount of dispersant used is 0.2 to 0.3 wt‰ of the slurry or iron-removed slurry.

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