A method for extracting lithium from amblygonite

Abstract

The application provides a method for extracting lithium from amblygonite. The specific steps are as follows: the amblygonite is crushed, ground and beneficiated to obtain powder materials with a particle size of less than or equal to 300 microns; then the obtained amblygonite powder is uniformly mixed with sodium hydroxide, calcium oxide and water in a certain proportion, and then pressure cooking is carried out under certain temperature and pressure, and then the lithium-containing leaching solution is obtained after cooling and filtration; the leaching solution is prepared into lithium carbonate after two times of carbonization and pyrolysis after impurity removal and concentration; the carbonization mother liquor and the pyrolysis mother liquor are added with a small amount of sodium hydroxide and then recycled as the circulating mother liquor. The leaching residue is washed and impurity-removed to obtain crude calcium phosphate, and aluminum hydroxide is obtained through secondary carbonization. The application realizes efficient extraction of amblygonite through a wet process, the lithium leaching rate can be as high as 99.5%, and high-temperature calcination or acid leaching process is not needed, so that the energy consumption is low, the process is short, the cost is low, and the method is green and environmentally friendly.

Description

Technical Field

[0001] This invention belongs to the field of lithium extraction technology from ores, and specifically relates to a method for extracting lithium from lithium phosphate rock. Background Technology

[0002] Lithium, as a light metal, plays a crucial role in battery technology, making it an increasingly important raw material for manufacturing lithium-ion batteries and widely used in various electronic devices and electric vehicles. Against the backdrop of global energy structure transformation and the rapid development of new energy vehicles, the demand for lithium resources continues to rise. Lithium sources include brine extraction and ore extraction. Brine reserves are abundant, but the complex elemental composition makes extraction difficult. In contrast, ore extraction has a long history, relatively mature technology, more stable raw material chemical composition, and easier process control, making it easier to produce high-purity lithium products. Currently, industrially produced lithium raw materials include spodumene, lithium feldspar, and lepidolite. With the gradual depletion of lithium ore resources, the demand for lithium ore resources is increasing. Lithium phosphate, as a mineral with a high lithium content, has significant development potential.

[0003] Lithium aluminum phosphate (LiAl(PO4)(OH)(F)) has a Li2O content of 4.0%–10.1%. It often occurs alongside other lithium ores, such as spodumene and potassium spodumene. Although LiAl(PO4)(OH)(F) constitutes a small proportion of lithium resources, its mining and utilization are receiving increasing attention due to rising lithium demand. Current lithium extraction methods from LiAl(PO4)(PO4)(OH)(F) primarily involve sulfuric acid roasting and sulfate roasting; however, these methods present several problems: 1. The presence of hydroxyl groups in LiAl(PO4)(PO4)(OH)(F) results in water formation upon acidification, leading to a thin, paste-like consistency and potential agglomeration and adhesion to the walls during calcination. 2. The presence of fluorine in LiAl(PO4)(PO4)(OH)(F) generates hydrofluoric acid during acid mixing, causing significant equipment corrosion and environmental impact. 3. The extraction methods are complex, generate SO3, require high heating temperatures (800℃–900℃), consume large amounts of energy, and result in low lithium extraction rates and low-purity lithium carbonate.

[0004] Chinese patent [CN202310961598.X] discloses a method for preparing lithium carbonate using lithium phosphate aluminum ore, which includes adding concentrated sulfuric acid to lithium phosphate aluminum ore powder to obtain a mixture, heating it to 500℃~600℃ for pyrolysis treatment, and then leaching the clinker to obtain aluminum phosphate residue. The leaching solution is used to remove impurities and precipitate lithium to obtain lithium carbonate. The method has a high lithium extraction rate and high purity of lithium carbonate, but it uses a large amount of sulfuric acid and the reaction temperature is high. The sulfuric acid mist formed causes serious corrosion to equipment, has high requirements for machinery and equipment, and has a high risk factor. It is also highly polluting, and the fact that most of the sulfuric acid forms acid mist also leads to incomplete reaction. Chinese patent [CN202111255770.7] discloses a method for extracting lithium from lithium phosphate aluminum ore raw materials by high-temperature calcination with sulfate, including processes such as crushing, calcination, grinding, leaching, and purification. By optimizing the ingredient composition, process chain, and controlling the calcination process nodes, it can reduce the production cost of lithium extraction and improve the recovery rate of lithium phosphate aluminum ore. However, it uses multiple metal salts, introduces other ions, and these are difficult to break down during calcination. It also uses a large amount of water, wasting resources. Chinese patent [CN117208942A] discloses a method for preparing lithium carbonate from lithium phosphate aluminum ore. After mixing, the material is first kept at 250-300℃ for 0.5-1 hour, and then calcined at 700-800℃ to obtain the calcined material. During the acid mixing process, the material becomes a thin paste, and equipment walls are severely sludged and corroded. The method of directly calcining after holding at the temperature results in an unstable reaction. Chinese patent [CN202411926160.9] discloses a method for the comprehensive utilization of lithium and phosphorus in lithium-bauxite ore, including grinding lithium-bauxite powder, mixing with concentrated sulfuric acid, solidification and roasting, leaching, impurity removal, concentration and lithium precipitation; the invention solves the problems of thin paste and equipment wall adhesion during the acid mixing process, reduces equipment corrosion and makes the reaction more stable, but produces water vapor and hydrogen fluoride gas during the solidification process, and requires two solidifications and one roasting, resulting in high energy consumption.

[0005] The sulfuric acid + sulfate acidification roasting method used in the aforementioned patent for processing lithium phosphate aluminum ore materials suffers from several drawbacks. The use of concentrated sulfuric acid during the reaction easily generates acid mist, and the mixed acid process produces a thin paste-like consistency and causes significant corrosion to equipment walls. Furthermore, the process is costly, generates hydrofluoric acid which is environmentally unfriendly, has a low lithium yield, and requires high-temperature roasting, resulting in high energy consumption. Therefore, there is a need to develop a lithium extraction method from lithium phosphate aluminum ore that offers high lithium yield, low cost, and a simple process flow. Summary of the Invention

[0006] To address the shortcomings of the prior art, this invention provides a method for extracting lithium from lithium phosphate aluminum ore, comprising the following steps: S1 processes lithium phosphate aluminum ore through crushing, grinding, and beneficiation to obtain powder material with a particle size ≤300 µm; S2 Mixed Pressure Cooking: Mix lithium aluminum phosphate with sodium hydroxide, lime water and water to make a slurry. Put the slurry into a reaction pressure vessel, start stirring and heating, and adjust the pressure in the reaction pressure vessel. Then, react at a constant temperature and pressure. After the reaction is completed, cool down. S3 Filtration and Washing: The cooled mixture obtained in S2 is subjected to solid-liquid separation to obtain leaching liquid and primary leaching residue. The leaching residue is washed with water and then subjected to solid-liquid separation again to obtain washing water and secondary leaching residue. The washing water is returned to S2 for batching to obtain leaching liquid. S4 Primary Carbonization: After removing impurities and concentrating the leachate obtained in S3, carbon dioxide is introduced into the solution for primary carbonization. After carbonization, the solution is filtered to obtain filtrate and filter residue. The carbonized filtrate is used as circulating mother liquor for recycling. S5 Secondary Carbonization: The filter residue obtained from S4 is slurried to obtain a slurry, and carbon dioxide is introduced for secondary carbonization. After carbonization, the filtrate and filter residue are obtained by filtration. S6 pyrolysis: Pyrolyze the filtrate obtained from S5 to obtain lithium carbonate.

[0007] The chemical reaction equations involved in each step of this invention are as follows: S2:

[0008] S4:

[0009] S5:

[0010] S6:

[0011] In some embodiments, the Li2O content in the lithium aluminum phosphate in S1 is 6.0 to 10.0%.

[0012] In some embodiments, the NaOH mass concentration of the mixture in S2 is 5% to 25%.

[0013] In some embodiments, the mass ratio of lime to water in S2 is (0-5):50.

[0014] In some embodiments, the liquid-to-solid ratio of the prepared slurry is (5-20):1.

[0015] In some embodiments, the pressure cooking temperature in S2 is 100–230°C, the pressure cooking time is 0.5–6 h, the stirring speed is 100–600 rpm / min, and the pressure is 0.1–4 MPa.

[0016] In some embodiments, during the primary carbonization described in S4, the pH of the leaching solution is 9 to 11.

[0017] In some embodiments, during the secondary carbonization described in S5, the pH of the slurry is 7-9, and the filter residue is aluminum hydroxide.

[0018] In some embodiments, the pyrolysis temperature described in S6 China is 60–90°C.

[0019] (1) This process uses lithium phosphate aluminum ore as raw material and calcium oxide and sodium hydroxide as auxiliary materials to carry out leaching reaction. Then, it successively carries out impurity removal, concentration, two carbonization and pyrolysis operations to prepare lithium carbonate, thereby achieving efficient extraction of metallic lithium from lithium phosphate aluminum powder and producing calcium phosphate and aluminum hydroxide as by-products.

[0020] (2) This invention does not require high-temperature calcination and has lower energy consumption; it uses calcium oxide or calcium hydroxide as an additive, which has low raw material cost and avoids the use of strong acids and high-value strong bases. (3) No concentrated sulfuric acid is used in the process, so no acid mist, wall formation or equipment corrosion will be generated, and no hydrofluoric acid will be produced, which is environmentally friendly.

[0021] (4) This method achieves efficient extraction of lithium phosphate aluminum stone through wet process technology, with a lithium extraction rate of over 99.5%. It does not require high-temperature calcination or acid leaching processes, and has the advantages of low energy consumption, short process, low cost, and green environmental protection. Attached Figure Description

[0022] Figure 1 This is a process flow diagram of a method for extracting lithium from lithium phosphate aluminum ore according to the present invention. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0024] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, are also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar to or equivalent to those described herein may be used in the implementation or testing of this invention.

[0026] Example 1

[0027] (1) The lithium aluminum phosphate (Li2O content is 8.91%) was crushed, ground and beneficiated to obtain powder material with a particle size ≤300μm; (2) Mixing and pressing: The phosphorus lithium aluminum stone powder obtained in step (1) is mixed with sodium hydroxide, lime and water in a ratio of 5:15:4:30 and stirred evenly at 200 r / min to form a slurry. The slurry is placed in a reaction pressure vessel and subjected to hydrothermal reaction at a reaction temperature of 200℃, a reaction time of 4 h and a reaction rate of 400 r / min. After the reaction is completed, the mixture is cooled down. (3) Filtration and washing: The cooled mixture obtained in step (2) is subjected to solid-liquid separation to obtain leaching liquid and leaching residue, wherein the lithium leaching rate is 99.21%. The leaching residue is washed with water and then subjected to solid-liquid separation to obtain washing water and qualified leaching residue. The washing water is returned to step (2) for batching. (4) First carbonization: After removing impurities and concentrating the lithium-containing leaching solution obtained in step (3) to a certain concentration, carbon dioxide is introduced into the solution until the pH is 10. After carbonization, the solution is filtered to obtain filtrate and filter residue. The carbonized filtrate is used as the circulating mother liquor for recycling. (5) Secondary carbonization: The filter residue obtained in step (4) is slurried and carbon dioxide is introduced to adjust the pH to 8.2. After carbonization, the filtrate and filter residue are obtained by filtration. (6) Pyrolysis: The filtrate obtained in step (5) is pyrolyzed at 80°C to obtain lithium carbonate, and the pyrolysis mother liquor is recycled.

[0028] Example 2

[0029] (1) The lithium aluminum phosphate (Li2O content is 8.91%) was crushed, ground and beneficiated to obtain powder material with a particle size ≤300μm; (2) Mixing and pressing: The phosphorus lithium aluminum stone powder obtained in step (1) is mixed with sodium hydroxide, lime and water in a ratio of 5:15:4:30 and stirred evenly at 200 r / min to form a slurry. The slurry is placed in a reaction pressure vessel and subjected to hydrothermal reaction at a reaction temperature of 230℃, a reaction time of 4 h and a reaction rate of 400 r / min. After the reaction is completed, the mixture is cooled down. (3) Filtration and washing: The cooled mixture obtained in step (2) is subjected to solid-liquid separation to obtain leaching liquid and leaching residue, wherein the lithium leaching rate is 99.53%. The leaching residue is washed with water and then subjected to solid-liquid separation to obtain washing water and qualified leaching residue. The washing water is returned to step (2) for batching. (4) First carbonization: After removing impurities and concentrating the lithium-containing leaching solution obtained in step (3) to a certain concentration, carbon dioxide is introduced into the solution until the pH is 9.5. After carbonization, the solution is filtered to obtain filtrate and filter residue. The carbonized filtrate is used as the circulating mother liquor for recycling. (5) Secondary carbonization: The filter residue obtained in step (4) is slurryed and carbon dioxide is introduced to adjust the pH to 8.1. After carbonization, the filtrate and filter residue are obtained by filtration. (6) Pyrolysis: The filtrate obtained in step (5) is pyrolyzed at 85°C to obtain lithium carbonate, and the pyrolysis mother liquor is recycled.

[0030] Example 3

[0031] (1) The lithium aluminum phosphate (Li2O content is 8.91%) was crushed, ground and beneficiated to obtain powder material with a particle size ≤300μm; (2) Mixing and pressing: The phosphorus lithium aluminum stone powder obtained in step (1) is mixed with sodium hydroxide, lime and water in a ratio of 5:15:4:30 and stirred at 200 r / min to form a slurry. The slurry is placed in a reaction pressure vessel and subjected to hydrothermal reaction at a reaction temperature of 180℃, a reaction time of 4 h and a reaction rate of 400 r / min. After the reaction is completed, the mixture is cooled down. (3) Filtration and washing: The cooled mixture obtained in step (2) is subjected to solid-liquid separation to obtain leaching liquid and leaching residue, wherein the lithium leaching rate is 99.11%. The leaching residue is washed with water and then subjected to solid-liquid separation to obtain washing water and qualified leaching residue. The washing water is returned to step (2) for batching. (4) First carbonization: After removing impurities and concentrating the lithium-containing leaching solution obtained in step (3) to a certain concentration, carbon dioxide is introduced into the solution until the pH is 10.3. After carbonization, the solution is filtered to obtain filtrate and filter residue. The carbonized filtrate is used as the circulating mother liquor for recycling. (5) Secondary carbonization: The filter residue obtained in step (4) is slurryed and carbon dioxide is introduced to adjust the pH to 7.8. After carbonization, the filtrate and filter residue are obtained by filtration. (6) Pyrolysis: The filtrate obtained in step (5) is pyrolyzed at 90°C to obtain lithium carbonate, and the pyrolysis mother liquor is recycled.

Claims

1. A method for extracting lithium from lithium phosphate rock, characterized in that, The method for extracting lithium from phosphate rock includes the following steps: S1 processes lithium aluminum phosphate rock through crushing, grinding, and beneficiation to obtain powder material with a particle size ≤300 µm; S2 Mixed Pressure Cooking: Mix lithium aluminum phosphate with sodium hydroxide, lime water and water to make a slurry. Put the slurry into a reaction pressure vessel, start stirring and heating, and adjust the pressure in the reaction pressure vessel. Then, react at a constant temperature and pressure. After the reaction is completed, cool down. S3 Filtration and Washing: The cooled mixture obtained in S2 is subjected to solid-liquid separation to obtain leaching liquid and primary leaching residue. The leaching residue is washed with water and then subjected to solid-liquid separation again to obtain washing water and secondary leaching residue. The washing water is returned to S2 for batching to obtain leaching liquid. S4 Primary Carbonization: After removing impurities and concentrating the leachate obtained in S3, carbon dioxide is introduced into the solution for primary carbonization. After carbonization, the solution is filtered to obtain filtrate and filter residue. The carbonized filtrate is used as circulating mother liquor for recycling. S5 Secondary Carbonization: The filter residue obtained from S4 is slurried to obtain a slurry, and carbon dioxide is introduced for secondary carbonization. After carbonization, the filtrate and filter residue are obtained by filtration. S6 pyrolysis: Pyrolyze the filtrate obtained from S5 to obtain lithium carbonate.

2. The method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, The Li2O content in the lithium aluminum phosphate rock described in S1 is 6.0–10.0%.

3. The method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, The NaOH mass concentration of the mixture described in S2 is 5% to 25%.

4. The method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, The mass ratio of lime to water in S2 is (0-5):

50.

5. The method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, The liquid-to-solid ratio of the prepared slurry is (5-20):

1.

6. The method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, The pressure cooking temperature described in S2 is 100–230℃, the pressure cooking time is 0.5–6h, the stirring speed is 100–600rpm / min, and the pressure is 0.1–4MPa.

7. The method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, During the first carbonization process described in S4, the pH of the leaching solution is 9–11.

8. A method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, During the secondary carbonization described in S5, the pH of the slurry is 7-9, and the filter residue is aluminum hydroxide.

9. A method for extracting lithium from lithium phosphate rock according to claim 1, characterized in that, The pyrolysis temperature specified in S6 China is 60–90℃.

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