Method for extracting lithium from lepidolite

Abstract

The present invention belongs to the field of lithium extraction, and specifically relates to a method for extracting lithium from lepidolite, wherein lepidolite and a leaching agent are mixed and leached under the assistance of ultraviolet light, followed by solid-liquid separation to obtain a lithium leaching solution; the leaching agent is a homogeneous solution containing formula 1#imgabs0# and formula 2#imgabs1#; the R1 is H, methyl or ethyl, and the n is 1 or 2; the R2 is H or hydroxyl; the R3 is a carboxyl or #imgabs2# wherein X is a carbon chain of C1 to C3 or a hydroxyl-substituted carbon chain. The present invention innovatively uses a homogeneous solution containing formula 1 and formula 2 as a leaching agent to perform ultraviolet-assisted leaching on lepidolite, and based on the physical and chemical synergy of the leaching agent and ultraviolet light, it can unexpectedly and effectively adapt to the physical and chemical characteristics of lepidolite, and can achieve efficient extraction of lithium from lepidolite under mild conditions. In addition, the process of the present invention can achieve good cyclic extraction and has excellent cyclic extraction stability.

Description

Technical Field

[0001] The present invention relates to the field of lithium extraction, and specifically to the field of lithium extraction from lithium ore. Background Art

[0002] Lithium is an important raw material for battery materials. Currently, the main sources of raw materials for lithium extraction are salt lake lithium, lithium ore and lithium-containing waste (such as waste battery materials). Although the methods of lithium extraction are mainly acid extraction, water extraction or alkaline extraction, different extraction objects and different physical and chemical properties will face different extraction problems, and it is difficult to simply transfer the lithium extraction process.

[0003] For example, in the case of lithium mica, the chemical composition is K{Li2-xAl1+x[Al2xSi4-2xO10](OH,F)2}(x=0-0.5), in which the lithium content is lower than that of the elements in the alkali metal family, and it is more difficult to extract than waste lithium-containing battery materials.

[0004] In view of the characteristics of lepidolite, most of the existing extraction processes need to be activated and transformed by means of relatively intense means. For example, the Chinese patent document with publication number CN118639032A discloses a method for efficiently extracting lithium by low-temperature calcination of spodumene lepidolite sulfuric acid, specifically recording that the lepidolite concentrate is evenly mixed with the spodumene concentrate and then subjected to high-temperature roasting, and then acid leaching. For another example, the Chinese patent document with publication number CN116240400A discloses a method for efficiently extracting lithium from lepidolite waste residues at low temperatures, specifically recording the scheme of leaching after the lepidolite waste residues are roasted with additives. In addition, the Chinese patent document with publication number CN115948655A discloses a method for comprehensively recovering lithium, rubidium and cesium from lepidolite slag, specifically recording the scheme of leaching with water and then removing impurities after the lithium slag is roasted at high temperature. The Chinese patent document with publication number CN115821060A discloses a method for extracting lithium from lepidolite by staged roasting using a composite salt method, which specifically records a scheme of leaching after mixing lepidolite powder with sodium sulfate, potassium sulfate, calcium sulfate, calcium carbonate, calcitriol powder, and a sulfur-increasing agent and sintering. In addition, the Chinese patent document with publication number CN114752784A discloses a process for improving the lithium leaching rate in lepidolite, which strengthens its leaching effect by adding lepidolite ore powder to an activator and a pore-forming agent and performing high-energy ball milling, pre-sintering, roasting, and other processes.

[0005] In summary, for the problems faced in the extraction of lithium mica, most of the methods in the industry need to rely on high-temperature roasting and other means to activate and transform it. In addition, the leaching stage still needs to rely on more intense leaching conditions. The industry still lacks simple and gentle methods for extracting lithium mica. Summary of the invention

[0006] In view of the problems faced by the existing lithium extraction from lepidolite ore, the present invention aims to provide a mild and efficient method for extracting lithium from lepidolite, aiming to provide a mild extraction process adapted to the characteristics of lepidolite.

[0007] Different from extracting lithium from waste lithium-ion battery positive electrode materials, lithium mica contains lithium, sodium, rubidium, cesium and other elements of the same family, and the relative content of lithium is significantly lower. Not only that, lithium is intercalated and coexists with other components in a complex natural crystal structure. The low lithium content and special physical and chemical structure characteristics of lithium mica will significantly increase the difficulty of lithium extraction. In response to the problems faced by lithium mica in extracting lithium, the main existing means are to roast or strongly activate the lithium mica, which will increase the process cost. In view of the current status of the industry, the present invention has been studied in depth and provides the following improvement scheme:

[0008] A method for extracting lithium from lepidolite, comprising mixing lepidolite and a leaching agent and leaching under the assistance of ultraviolet light, followed by solid-liquid separation to obtain a lithium leaching solution;

[0009] The leaching agent is a homogeneous solution containing formula 1 and formula 2;

[0010]

[0011] The R 1 is H, methyl or ethyl, wherein n is 1 or 2; wherein R 2 is H or hydroxyl;

[0012] The R 3 Carboxyl or Where X is C 1 ~C 3 The carbon chain or hydroxyl substituted carbon chain.

[0013] The present invention innovatively uses a homogeneous solution containing Formula 1 and Formula 2 as a leaching agent to perform UV-assisted leaching on lepidolite. Based on the physicochemical synergy of the leaching agent and UV, it can unexpectedly and effectively adapt to the physicochemical characteristics of lepidolite, and can achieve efficient extraction of lithium from lepidolite under mild conditions. In addition, the process of the present invention can achieve good cyclic extraction and has excellent cyclic extraction stability.

[0014] In the present invention, there is no particular requirement for the content of Li in the lepidolite ore. Considering the economic and value of the process, the lithium content of the lepidolite ore can be above 5wt.% (in terms of Li 2 (O calculation).

[0015] The particle size of lithium mica is controlled at -100 mesh.

[0016] In the present invention, in the leaching agent, the formula 1 is a compound of formula 1A and / or formula 1B;

[0017]

[0018] In the present invention, the formula 2 is at least one of formula 2A, formula 2B, formula 2C and formula 2D;

[0019]

[0020] In the present invention, the formula 1 and the formula 2 are mixed at a temperature of 50 to 90° C. to obtain the leaching agent.

[0021] In the present invention, the molar ratio of Formula 1 to Formula 2 is 1:0.5-3; further, it can be 1:1-1.5.

[0022] In the present invention, in the leaching stage, the weight ratio of the leaching agent to the lepidolite can be adjusted as needed, but considering the economic and process value, it is further 5 to 10:1 (further 5 to 8:1). The present invention can unexpectedly obtain excellent lithium extraction effect and effect of lepidolite at a low leaching agent dosage.

[0023] In the present invention, the wavelength of ultraviolet light in the leaching stage is 250 to 380 nm;

[0024] Preferably, the temperature in the leaching stage is 45-100°C, and further can be 50-80°C.

[0025] Preferably, the leaching time is 10 to 60 minutes; further, it can be 15 to 50 minutes.

[0026] Preferably, the leaching stage is carried out at a pressure of 0.2-1 MPa (or further 0.2-0.5 MPa). The present invention shows that under this preferred condition, it is helpful to combine with the leaching agent and the ultraviolet process, which helps to further solve the problems faced by lepidolite leaching and can obtain a better synergistic leaching effect.

[0027] After the extraction of the present invention is completed, solid-liquid separation can be performed based on conventional methods, such as centrifugation or filtration.

[0028] In the present invention, the lithium leaching solution is subjected to carbonation or phosphorylation treatment, and then solid-liquid separation is performed to obtain lithium precipitate and precipitate mother liquor.

[0029] In the present invention, the precipitation mother liquor is used as a leaching agent and is circulated for leaching of lepidolite.

[0030] The process of the present invention can realize the recycling of the leaching agent, and the recycling leaching performance is excellent.

[0031] Beneficial Effects

[0032] The present invention innovatively uses a leaching agent comprising Formula 1 and Formula 2 to leach lithium mica, and in view of the problems faced by lithium mica leaching, innovatively performs leaching by ultraviolet assistance, thereby achieving synergy, adapting to the characteristics of lithium mica, and realizing efficient extraction of lithium from lithium mica. In addition, the process of the present invention can achieve good cyclic extraction and has excellent cyclic extraction stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the cyclic leaching rate diagram of Example 1. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below in conjunction with specific embodiments, but the present invention is not limited to the following embodiments.

[0035] The lithium mica of the present invention can be conventional lithium mica, for example, as an optional solution, its hardness is between 2-3, the density is 2.8-2.9, the particle size is 0.1-0.3 mm, Li 2 The content of O is 5.4-5.6 wt.%.

[0036] In the present invention, the leaching agent is a homogeneous solution prepared by mixing Formula 1 and Formula 2 at a temperature of 75 to 85°C.

[0037] Embodiment 1:

[0038] Step 1:

[0039] The lepidolite is washed, filtered, dried, and then crushed by a vibration mill to pass through a 200-mesh sieve to obtain the lepidolite to be treated;

[0040] Step 2:

[0041] The leaching agent (in this case, Formula 1 (in this case, Formula 1A) and Formula 2 (in this case, Formula 2A) with a molar ratio of 1:1) and the lithium mica to be treated are mixed in a weight ratio of 6:1, and leached under the assistance of 254nm ultraviolet light. The temperature of the leaching stage is controlled at 60°C and the reaction time is 30min.

[0042] Sodium carbonate is added to separate lithium. Sodium carbonate is added in a ratio of 1:2 to the theoretical amount of lithium in a water bath at 90°C, and the mixture is kept warm for 2 hours. The mixture is then filtered while hot to obtain a lithium carbonate precipitate and a solution. After filtration, the solid is washed with water and dried to obtain lithium carbonate. The solution is adjusted to pH and component ratio consistent with the original leaching agent solution by adding dilute hydrochloric acid, and then a new leaching cycle is carried out.

[0043] The leaching rate of Li in the first leaching was 99.3%, and the purity of the collected lithium carbonate was 97%. Reusing the leaching agent was able to maintain a Li leaching rate of 98.2% after 5 cycles.

[0044] Example 2

[0045] Compared with Example 1, the only difference is that the formula 2 is changed, and the other operations and parameters are the same as those of Example 1. The experimental groups are:

[0046] Group A: Formula 2 is Formula 2B; the initial lithium leaching rate is 99.1%, and the lithium leaching rate after 5 cycles can reach 98.1%;

[0047] Group B: Formula 2 is Formula 2C; the initial lithium leaching rate is 99.4%, and the lithium leaching rate after 5 cycles can reach 98.5%;

[0048] Group C: Formula 2 is Formula 2D; the initial lithium leaching rate is 99.5%, and the lithium leaching rate after 5 cycles can reach 98.6%.

[0049] Example 3

[0050] Compared with Example 1, the only difference is that the formula 1 in the leaching agent is changed to the formula The initial lithium leaching rate was 99.1%, and the lithium leaching rate after five cycles could reach 98.1%.

[0051] Example 4

[0052] Compared with Example 1, the only difference is that the liquid-to-solid ratio of the leaching agent, temperature, ultraviolet band, temperature and time in the leaching stage are changed. Specifically, the ratio of Formula 1 to Formula 2 is 1:1.5; the weight ratio of liquid to solid in the leaching stage is 8:1, the leaching temperature is 80°C, and the wavelength of ultraviolet is 300nm; the leaching time is set to 50min.

[0053] The initial lithium leaching rate was 99.4%, and the lithium extraction efficiency after 5 cycles was still 98.3%.

[0054] Embodiment 5:

[0055] Compared with Example 1, the only difference is that air is used for pressurization in the leaching stage, and the pressure in the leaching stage is controlled to be 0.2-0.4 MPa. In addition, the temperature in the leaching stage is controlled to be 50° C., the liquid-to-solid ratio in the leaching stage is 5:1, and the leaching time is 20 min. Other operations and parameters are the same as in Example 1.

[0056] The initial lithium leaching rate was 99.6%, and the lithium extraction efficiency after 5 cycles was 98.7%.

[0057] It can be seen that the use of positive pressure-assisted leaching can achieve better leaching effect and efficiency, and can achieve equivalent or even better leaching effect in a shorter time and at a milder temperature.

[0058] Comparative Example 1

[0059] Compared with Example 1, the only difference is that no ultraviolet irradiation is performed during the leaching stage, and other operations and parameters are the same as in Example 1.

[0060] The initial Li leaching rate was 80.3%, and the Li leaching rate decayed to 73.1% after two cycles.

[0061] Comparative Example 2

[0062] Compared with Example 1, the only difference is that urea or acetylamine is used in the leaching agent to replace Formula 1 in the leaching agent in equal moles, and other operations and parameters are the same as those in Example 1.

[0063] The results of urea or acetylamide were: the first Li leaching rate was 83.7% or 86.1% respectively; the lithium leaching rate decayed to 75.2% or 73.5% after two cycles.

[0064] Comparative Example 3

[0065] Compared with Example 1, the only difference is that acetic acid or benzoic acid is used to replace the formula 2 in the leaching agent in equal moles, and other operations and parameters are the same as those in Example 1.

[0066] The leaching of acetic acid or benzoic acid is respectively: the leaching rate of Li in the first leaching solution is 88.9% or 89.4%; the leaching rate of lithium decays to 79.3% or 76.1% after two cycles.

[0067] It can be seen from Example 1 and Comparative Examples 1 to 3 that the use of the combined leaching agent of Formula 1-Formula 2 described in the present invention in conjunction with the ultraviolet leaching process can achieve synergy, can solve the problems faced by lithium mica leaching, and can effectively extract lithium under mild conditions.

Claims

1. A method for extracting lithium from lepidolite, characterized in that: The lithium mica and the leaching agent are mixed and leached under the assistance of ultraviolet light, followed by solid-liquid separation to obtain a lithium leaching solution; The leaching agent is a homogeneous solution containing formula 1 and formula 2; The R1 is H, methyl or ethyl, the n is 1 or 2; the R2 is H or hydroxyl; The R3 is a carboxyl group or Wherein, X is a C1-C3 carbon chain or a hydroxyl-substituted carbon chain.

2. The method for extracting lithium from lepidolite as claimed in claim 1, characterized in that: The particle size of lithium mica is controlled at -100 mesh.

3. The method for extracting lithium from lepidolite as claimed in claim 1, characterized in that: In the leaching agent, the formula 1 is a compound of formula 1A and / or formula 1B; 4. The method for extracting lithium from lepidolite as claimed in claim 1, characterized in that: The formula 2 is at least one of formula 2A, formula 2B, formula 2C and formula 2D; 5. The method for extracting lithium from lepidolite as claimed in claim 1, characterized in that: The leaching agent is obtained by mixing the formula 1 and the formula 2 at a temperature of 50 to 90°C.

6. The method for extracting lithium from lepidolite according to claim 1, characterized in that: The molar ratio of Formula 1 to Formula 2 is 1:0.5-3.

7. The method for extracting lithium from lepidolite according to claim 1, characterized in that: In the leaching stage, the weight ratio of the leaching agent to the lithium mica is 5 to 10:

1.

8. The method for extracting lithium from lepidolite as claimed in claim 1, characterized in that: The wavelength of ultraviolet light in the leaching stage is 250-380nm; Preferably, the temperature in the leaching stage is 45-100°C; Preferably, the leaching time is 10 to 60 minutes; further, it can be 15 to 50 minutes; Preferably, the leaching stage is carried out at a pressure of 0.2-1 MPa.

9. The method for extracting lithium from lepidolite according to any one of claims 1 to 8, characterized in that: The lithium leaching solution is subjected to carbonation or phosphorylation treatment, followed by solid-liquid separation to obtain lithium precipitate and precipitate mother liquor.

10. The method for extracting lithium from lepidolite according to claim 9, characterized in that: The precipitation mother liquor is used as a leaching agent and recycled for leaching of lepidolite.

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