A high-concentration flotation recovery method for fine-grained lepidolite

Abstract

This invention discloses a high-concentration flotation recovery method for fine-grained lepidolite. The method involves preparing a slurry from fine-grained lepidolite ore and garnet ore; adding inhibitors and collectors to the slurry followed by aerated flotation to obtain lepidolite concentrate and tailings; the slurry concentration is greater than 45%. This invention alters the rheological properties of the slurry by adding hydrophilic garnet, reducing its viscosity and enhancing the dispersion of mineral particles, thus achieving efficient recovery of fine-grained lepidolite. The process of this invention uses low reagent dosages, is simple, and highly operable, making it significant for the recovery and utilization of fine-grained lepidolite resources.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology and relates to a high-concentration flotation recovery method for fine-grained lepidolite. Technical Background

[0002] Lithium, as an essential new raw material for modern technological development, is widely used in numerous fields such as lithium-ion batteries, nuclear industry, and solid fuels. Lepidolite, as a lithium-bearing mineral with relatively large reserves in my country, is one of the most important resources for lithium extraction. During the mineralization, weathering, and grinding processes of lithium deposits, a large number of fine-grained minerals are produced. These layered aluminosilicate minerals have similar crystal structures and chemical properties, generally low valuable metal grades, and fine particle sizes. In particular, the difficulty in recovering the extremely fine minerals from over-ground fine mud products hinders the efficient recovery of lithium resources.

[0003] Research on the flotation of fine-grained lepidolite is limited. Regarding reagents, combined anion and cation collectors exhibit strong synergistic effects and high surface activity in the flotation of conventional-sized lepidolite, demonstrating better collection and selectivity compared to single collectors, and being more economical and practical than novel collectors. However, there is a lack of research on specific reagents for micro-fine lepidolite. Research on recovery technologies for fine-grained minerals mainly focuses on increasing the apparent particle size of the minerals and reducing bubble size, including flocculation flotation, carrier flotation, and microbubble flotation. However, research on these methods in the field of lepidolite flotation is relatively lacking. For example, Chinese patent CN116889932A uses water glass, caustic starch and carboxymethyl cellulose as a combination of inhibitors and a combination of collectors to achieve the recovery of fine-grained lepidolite from desliming products through depressurized flotation column flotation. However, this technology mainly relies on depressurizing the product to generate micro-nano bubbles to achieve fine-grained flotation. Therefore, it is necessary to strictly control the pressure of the pre-flotation slurry conditioning process. The process is complex and the requirements for equipment are relatively strict, which limits its industrial application.

[0004] Currently, there are no suitable methods for processing fine-grained lithium resources in industry, resulting in a significant loss of most of these resources. With the continuous rise in lithium metal prices, some concentrators have attempted to use flotation columns for recovery, but the effectiveness still needs improvement due to the excessively fine particle size.

[0005] Therefore, developing a process for the flotation of fine-grained lepidolite is of great significance for the efficient recovery of lithium resources. Summary of the Invention

[0006] To address the shortcomings of existing technologies in the flotation of fine-grained lepidolite, the present invention aims to provide a high-concentration flotation recovery method for fine-grained lepidolite that is simple to implement and requires low reagent dosage. This method regulates the rheological properties of the pulp by adding the hydrophilic mineral garnet, while increasing the pulp concentration to improve the collision probability between mineral particles and bubbles. In conjunction with inhibitors and collectors, the hydrophobicity difference between the target mineral and gangue minerals is enhanced, thereby synergistically improving the flotation effect of fine-grained lepidolite.

[0007] To achieve the above-mentioned technical objectives, the present invention provides a high-concentration flotation recovery method for fine-grained lepidolite. The method involves preparing a slurry by conditioning fine-grained lepidolite ore and garnet ore; adding inhibitors and collectors to the slurry and then performing aerated flotation to obtain lepidolite concentrate and tailings; the concentration of the slurry is greater than 45%.

[0008] The key to this invention lies in using garnet ore to regulate the rheological properties of the slurry, while simultaneously increasing the slurry concentration to enhance the collision probability between mineral particles and bubbles. Through the synergistic effect of inhibitors and collectors, the flotation effect of fine-grained lepidolite is improved. In this invention, because garnet is a naturally hydrophilic mineral with good dispersion in water, it can effectively disrupt flocs in the mixed mineral slurry as a stirring medium, possessing the potential to limit heterogeneous aggregation between lepidolite and its gangue minerals. The inventors have found that garnet particles can effectively reduce the apparent viscosity and yield stress of the mixed slurry, thereby improving flotation performance in the presence of fine-grained gangue minerals. Furthermore, there is a strong correlation between flotation rate, slurry rheology, and floc morphology. As the garnet content in the flotation slurry increases, the viscosity of the flotation slurry decreases, and the flotation recovery rate increases; the floc morphology changes from large branched to spherical, and the flotation foam becomes cleaner. In addition, the changes in the fluid properties of the flotation slurry caused by garnet addition are closely related to flotation selectivity. As the yield stress of the ore pulp decreases, the flotation recovery rate increases and the selectivity improves. On the other hand, the inventors discovered that high-concentration flotation increases the collision probability between bubbles and mineral particles, strengthens adhesion, and thus increases flotation speed while saving reagent costs and water consumption. Furthermore, the flotation speed increases with increasing flotation concentration; at the same reaction order, higher pulp concentration results in faster flotation speed. During the flotation process, the expansion rate of the three-phase wetting periphery is crucial to the flotation performance of minerals. The collision speed between bubbles and mineral particles affects the rupture of their surface hydration film and the formation of the three-phase wetting periphery. Generally, high-concentration flotation can reduce the relative velocity between mineral particles and bubbles, increase their contact time, effectively improve their adhesion probability, and enhance the flotation effect. Therefore, in the technical solution of this invention, by increasing the pulp concentration during the ore blending process, the collision probability between bubbles and mineral particles is increased, strengthening adhesion, thereby improving the flotation speed and saving reagent costs and water consumption. The added garnet, as a stirring medium, effectively breaks down flocculants in the mixed mineral pulp, reducing the amount of inhibitor required. Furthermore, by adding inhibitors to adjust the hydrophilicity of gangue minerals and improve their dispersibility, combined with the synergistic effect of collectors that selectively increase the hydrophobicity of fine-grained lepidolite, efficient recovery of fine-grained lepidolite was achieved.

[0009] As a preferred embodiment, the pulp concentration is 45-60%. The pulp concentration of this invention is relatively high compared to conventional flotation pulp concentrations. This is mainly because this invention primarily targets the small particle size of lepidolite ore, making effective capture and recovery difficult at lower pulp concentrations. Higher concentration flotation reduces the relative velocity between mineral particles and air bubbles, increases their contact time, effectively improves their adhesion probability, and enhances the flotation effect. However, excessively high pulp concentrations prevent fine lepidolite mineral particles and air bubbles from flowing freely, disrupting the aeration process and leading to a decrease in flotation recovery.

[0010] As a preferred embodiment, the concentration of the fine-grained lepidolite ore in the slurry is 35-45%.

[0011] As a preferred embodiment, the mass of the garnet ore is 23-30% of the mass of the lepidolite ore. In this invention, the amount of garnet ore used has a certain impact on the grade of the target mineral and the recovery rate of Li₂O. For example, excessive garnet usage will affect the content of the target mineral in the slurry, indirectly reducing the grade of the target mineral; moreover, it will increase the production load in industrial production. Conversely, insufficient garnet usage will fail to regulate the rheological properties of the slurry.

[0012] As a preferred embodiment, the fine-grained lithium mica ore has a particle size of -300 mesh accounting for more than 50%.

[0013] As a preferred embodiment, the garnet ore has a particle size of -200 mesh, comprising 50%. If the garnet ore particle size is too small, it will not reduce the viscosity of the slurry and may even increase it. Conversely, if the particle size is too large, its weight will increase the force of particle shedding. Excessively coarse garnet ore is difficult to adhere to air bubbles, leading to metal loss and affecting the improvement of concentrate grade.

[0014] As a preferred embodiment, the inhibitor is prepared by combining sodium hexametaphosphate and water glass in a mass ratio of (2-4):(1-1.5). The water glass added in this invention can pass through highly hydrating HSiO3. - The water glass interacts with the silicate particles on the surface of lepidolite, thereby adsorbing onto the lepidolite surface and improving its hydrophilicity. Sodium hexametaphosphate, on the other hand, is pre-adsorbed onto the lepidolite surface in the form of phosphate colloids, leading to a weakening of subsequent collector adsorption on the mineral surface and increasing the hydrophilicity of lepidolite. Therefore, by combining water glass and sodium hexametaphosphate in the preferred mass ratio of this invention to form a combined inhibitor, the hydrophilicity of gangue minerals can be jointly regulated, allowing the target mineral and gangue minerals to disperse in the slurry. This also helps to disperse gangue minerals and target mineral particles, reducing entrainment.

[0015] As a preferred embodiment, the collector is a compound of dodecylamine, sodium oleate, sodium dodecyl sulfonate, and oxidized paraffin soap in a mass ratio of (1-4):(1-2):1:2. Since lepidolite has a relatively constant negative charge on its surface, and dodecylamine exists primarily as a cation in solution, while sodium oleate, sodium dodecyl sulfonate, and oxidized paraffin soap exist as anions, the cations are first adsorbed onto the lepidolite surface. Subsequently, the anions undergo electrochemical neutralization to produce co-adsorption, thereby forming a complex that enhances the hydrophobicity of the mineral. This invention employs a collector combining anions and cations, resulting in a surface tension and critical micelle concentration far lower than that of a single component, leading to stronger activity and the generation of smaller, more stable bubbles, which is beneficial for the flotation process. Furthermore, the dodecylamine, sodium oleate, and oxidized paraffin soap used in this invention, in addition to their collecting ability, also possess bubble-forming properties, further improving the flotation efficiency of lepidolite.

[0016] As a preferred embodiment, the inhibitor is prepared into an aqueous solution and added directly; the collector is prepared into a solution with water at 40-50°C and added.

[0017] As a preferred embodiment, the aerated flotation includes one roughing stage, at least one scavenging stage, and at least one cleaning stage.

[0018] As a preferred embodiment, the flotation reagent system for roughing is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 5-20 g / t, and the amount of collector relative to the fine-grained lepidolite ore is 350-450 g / t.

[0019] As a preferred embodiment, the flotation reagent system for scavenging is as follows: the amount of collector relative to the fine-grained lepidolite ore is 50-100 g / t.

[0020] As a preferred embodiment, the selected flotation reagent system is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 0-5 g / t.

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

[0022] 1) This invention uses garnet ore to regulate the rheological properties of the slurry, while increasing the slurry concentration to improve the collision probability between mineral particles and bubbles. A combination of inhibitors and collectors is introduced to further synergistically enhance the flotation process by strengthening the hydrophobic difference between the target mineral and gangue minerals. This invention effectively achieves efficient recovery of fine-grained lepidolite through the combination of garnet flotation media, high-concentration flotation process, combined inhibitors, and anionic / cationic combined collectors.

[0023] 2) The process of this invention is simple, the amount of reagents used is low, and the economic benefits are high. It is of great significance for the efficient and comprehensive utilization of fine-grained lithium resources. Attached Figure Description

[0024] Figure 1 The above are flotation process flow diagrams for Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 4.

[0025] Figure 2 This is a flow chart of the flotation process in Example 2.

[0026] Figure 3 This is a flow chart of the flotation process for Comparative Example 3. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments. Obviously, the embodiments described below are only a part of the embodiments, and all other embodiments obtained by those skilled in the art without creative effort are still within the scope of protection of the present invention.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0029] Example 1

[0030] This embodiment uses a fine-grained lepidolite ore from Hunan Province with a Li2O grade of 0.58%. The fine mud has a -38μm (-400 mesh) particle size of 56.54%, and the main useful mineral is lepidolite, while the gangue minerals are mainly quartz and feldspar.

[0031] In this embodiment, the inhibitor is prepared by compounding sodium hexametaphosphate and water glass in a mass ratio of 2:1, and the collector XLC is prepared by compounding dodecylamine, sodium oleate, sodium dodecyl sulfonate, and oxidized paraffin soap in a mass ratio of 4:1:1:2. The collector XLC is prepared into a 5% solution with 50°C warm water before use.

[0032] The process flow of this embodiment is as follows: Figure 1 As shown, the specific steps and pharmaceutical preparation methods are as follows:

[0033] 1) Ore blending: Fine-grained lepidolite ore and garnet flotation medium are added to the flotation cell. The garnet flotation medium has a particle size of -200 mesh and accounts for 50% of the total ore content, while the garnet ore accounts for 30% of the mass of the lepidolite ore. The total pulp concentration is 50%.

[0034] 2) Adding reagents: No pH adjustment is required. Add 5 g / t of inhibitor to the slurry in sequence, stir for 3 min, add 350 g / t of collector XLC3, stir for 3 min to obtain a slurry containing lepidolite, garnet medium and reagents.

[0035] 3) Lithium flotation: Aerated flotation is carried out in a flotation machine. The flotation process consists of one roughing, two cleaning, and two scavenging stages, ultimately yielding lepidolite concentrate and tailings. The reagent regime for roughing is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 5 g / t, and the amount of collector relative to the fine-grained lepidolite ore is 350 g / t. The reagent regime for the first cleaning stage is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 5 g / t. The reagent regime for the second cleaning stage is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 0 g / t. The reagent regime for the first scavenging stage is as follows: the amount of collector relative to the fine-grained lepidolite ore is 100 g / t. The reagent regime for the second scavenging stage is as follows: the amount of collector relative to the fine-grained lepidolite ore is 50 g / t.

[0036] The results of the closed-loop test of the entire process are shown in Table 1. It can be seen that the final lepidolite concentrate with a Li2O grade of 1.85% and a Li2O recovery rate of 90.10% was obtained; and the lepidolite tailings with a Li2O grade of 0.08% and a Li2O recovery rate of 9.90% were obtained.

[0037] Table 1 Results of the full-process closed-circuit test

[0038] Product Name Yield / % <![CDATA[Li2O grade / %]]> <![CDATA[Li2O Recovery Rate / %]]> Concentrate 28.25 1.85 90.10 Tailings 71.75 0.08 9.90 raw ore 100.00 0.58 100.00

[0039] Example 2

[0040] This embodiment uses fine-grained lepidolite from Jiangxi Province, with a Li₂O grade of 0.43%. The fine mud contains 89.08% -50μm (-300 mesh) particles, and the main gangue minerals include quartz, feldspar, and calcite. The main valuable metallic mineral is lepidolite.

[0041] The process flow in this embodiment is the same as in Example 1, except for the dosage of the reagents. The inhibitor is composed of sodium hexametaphosphate and water glass in a mass ratio of 2:1, and the collector XLC is composed of dodecylamine, sodium oleate, sodium dodecyl sulfonate, and oxidized paraffin soap in a mass ratio of 3:1:1:2. The collector XLC is prepared into a 5% solution with 50°C warm water before use.

[0042] The process flow of this embodiment is as follows: Figure 2 As shown, the specific steps and pharmaceutical preparation methods are as follows:

[0043] 1) Ore blending: Fine-grained lepidolite ore and garnet flotation medium are added to the flotation cell. The garnet flotation medium has a particle size of -200 mesh and accounts for 50% of the total ore content, while the garnet ore accounts for 30% of the mass of the lepidolite ore. The total concentration of the pulp is 48%.

[0044] 2) Adding reagents: No pH adjustment is required. Add 10g / t of inhibitor to the slurry in sequence, stir for 3 min, and add 450g / t of collector XLC4, stir for 3 min to obtain a slurry containing lepidolite, garnet medium and reagents.

[0045] 3) Lithium flotation: Aerated flotation is carried out in a flotation machine. The flotation process consists of one roughing, two cleaning, and two scavenging stages, ultimately yielding lepidolite concentrate and tailings. The reagent regime for the roughing stage is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 10 g / t, and the amount of collector relative to the fine-grained lepidolite ore is 450 g / t. The reagent regime for the first cleaning stage is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 5 g / t; the reagent regime for the second cleaning stage is as follows: the amount of inhibitor relative to the fine-grained lepidolite ore is 0 g / t. The reagent regime for the first scavenging stage is as follows: the amount of collector relative to the fine-grained lepidolite ore is 100 g / t; the reagent regime for the second scavenging stage is as follows: the amount of collector relative to the fine-grained lepidolite ore is 50 g / t.

[0046] The results of the closed-loop test of the entire process are shown in Table 2. It can be seen that the final lepidolite concentrate with a Li2O grade of 1.67% and a Li2O recovery rate of 83.57% was obtained; and the lepidolite tailings with a Li2O grade of 0.09% and a Li2O recovery rate of 16.43% were obtained.

[0047] Table 2 Results of the full-process closed-circuit test

[0048] Product Name Yield / % <![CDATA[Li2O grade / %]]> <![CDATA[Li2O recovery rate / %]]> Concentrate 21.52 1.67 83.57 Tailings 78.48 0.09 16.43 Fine clay ore 100.00 0.43 100.00

[0049] Comparative Example 1

[0050] Using the fine-grained lepidolite from Example 1 as the raw ore, and employing the same reagent regimen and flotation process as in Example 1, the effect of garnet flotation medium on the flotation of fine-grained lithium ore was investigated. The process flow is as follows: Figure 1 As shown.

[0051] The experimental results are shown in Table 3. It is evident that without garnet flotation medium, the concentrate grade is low and there is no significant enrichment. Using garnet flotation medium increases the flotation recovery rate and has a significant strengthening effect.

[0052] Table 3 Results of tests with and without garnet flotation media

[0053]

[0054] Comparative Example 2

[0055] Using the fine-grained lepidolite from Example 1 as the raw ore, and employing the same reagent regimen and flotation process as in Example 1, the effect of pulp concentration on the flotation of fine-grained lithium ore was investigated. The process flow is as follows: Figure 1 As shown.

[0056] The experimental results are shown in Table 4. It can be seen that when the slurry concentration is low, the lithium concentrate grade is low and there is no obvious enrichment; within the experimental range, the lithium oxide recovery rate gradually increases with the increase of slurry concentration.

[0057] Table 4 Results of pulp concentration test

[0058]

[0059] Comparative Example 3

[0060] Using the fine-grained lepidolite from Example 1 as the raw ore, dodecylamine was used as the collector and sodium hexametaphosphate as the depressant. The remaining flotation process was the same as in Example 1. The effect of reagent type on the flotation of fine-grained lithium ore was investigated. The process flow is as follows: Figure 3 As shown.

[0061] The experimental results are shown in Table 5. It can be seen that when dodecylamine is used as the collector and sodium hexametaphosphate as the inhibitor, the lithium concentrate grade is low and there is no significant enrichment, which is significantly different from the combined collector and inhibitor effect in this invention.

[0062] Table 5. Results of the test on the types of pharmaceuticals

[0063]

[0064] Comparative Example 4

[0065] Using the fine-grained lepidolite from Example 1 as the raw ore, and employing the same reagent regimen and flotation process as in Example 1, the effects of garnet particle size and proportion on the flotation of fine-grained lithium ore were investigated. The process flow is as follows: Figure 1 As shown.

[0066] The experimental results are shown in Table 6. It can be seen that when the garnet particle size or concentration is outside the scope of this invention, the lithium concentrate grade and recovery rate are both low.

[0067] Table 6. Test results of garnet particle size and proportion

[0068]

Claims

1. A method for high-density flotation recovery of fine-grained lepidolite, characterized by: The fine-grained spodumene and garnet ore are treated by slurry conditioning to obtain a slurry; the slurry is added with an inhibitor and a collector and then subjected to air flotation to obtain a spodumene concentrate and a tailing; the concentration of the slurry is greater than 45%; The mass of the garnet ore is 23-30% of the mass of the fine-grained spodumene; The inhibitor is compounded by sodium hexametaphosphate and water glass at a mass ratio of (2-4):(1-1.5); The collector is compounded by dodecylamine, sodium oleate, sodium dodecyl sulfonate and oxidized paraffin soap at a mass ratio of (1-4):(1-2):1:

2.

2. The method of high-density flotation recovery of fine particle lepidolite according to claim 1, characterized in that: The concentration of the slurry is 45-60%.

3. A method for high-density flotation recovery of fine particle-lithium mica according to claim 1 or 2, characterized in that: The concentration of the fine-grained spodumene in the slurry is 35-45%.

4. The method of high-density flotation recovery of fine particle lepidolite according to claim 3, characterized in that: The particle size of the fine-grained spodumene is greater than 50% of -300 mesh.

5. A process for the high density flotation recovery of fine spodumene as claimed in claim 4, characterised in that: The particle size of the garnet ore is 50% of -200 mesh.

6. A process for the high density flotation recovery of fine spodumene as claimed in claim 4 or 5, characterised in that: The air flotation includes one roughing, at least one scavenging and at least one cleaning.

7. The high-concentration flotation recovery method of fine-grained spodumene according to claim 6, characterized in that: The dosage of the inhibitor relative to the fine-grained spodumene is 5-20 g / t, and the dosage of the collector relative to the fine-grained spodumene is 350-450 g / t; The dosage of the collector relative to the fine-grained spodumene is 50-100 g / t; The dosage of the inhibitor relative to the fine-grained spodumene is 0-5 g / t.

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