Method for synergistically extracting lithium from spodumene and mica

Abstract

This invention discloses a method for synergistic lithium extraction from spodumene and mica. The method includes the following steps: 1) flotation of spodumene ore to obtain spodumene concentrate with a potassium oxide content of 1-5 wt%; 2) mixing the spodumene concentrate with a transformation aid and a binder to form pellets, followed by roasting to obtain transformed spodumene; 3) acid leaching the transformed spodumene to obtain a lithium-potassium leaching solution; 4) sequentially adding potassium ferric sulfate seed crystals and ferric sulfate to the lithium-potassium leaching solution for potassium precipitation, and separating the reaction products by solid-liquid separation to obtain a potassium-removed solution and potassium ferric sulfate precipitate; 5) purifying the potassium-removed solution by adjusting the pH to obtain a lithium-purified solution. This method significantly improves the spodumene flotation recovery rate and lithium-potassium separation efficiency, resulting in a high-purity lithium solution with low impurity content. Furthermore, the method is simple, energy-efficient, and cost-effective, making it suitable for industrial applications.

Description

Technical Field

[0001] This invention relates to a method for extracting lithium from spodumene ore, and particularly to a method for synergistic lithium extraction from spodumene and mica, belonging to the field of deep extraction of lithium resources. Background Technology

[0002] Lithium extraction in my country can be mainly divided into two directions: brine extraction and lithium ore extraction. Lithium ore extraction has attracted much attention in the domestic lithium extraction industry due to its advantages of high production efficiency and high lithium recovery rate, especially the extraction of lithium from spodumene. Currently, methods for extracting lithium from spodumene can be summarized as the sulfuric acid process, limestone process, sulfate roasting process, chlorination roasting process, and alkaline pressure cooking process. The sulfuric acid process is widely used industrially due to its simple process and high lithium extraction rate, but this method still faces some problems that urgently need to be solved.

[0003] High energy consumption is a problem that must be faced in the lithium extraction process from spodumene. Natural α-spodumene must be calcined at 1000-1100℃ for 1-2 hours to be converted into easily leached β-spodumene, which is the main energy-consuming process in lithium extraction from spodumene. Secondly, the difficulty in efficiently separating elements with similar properties is an unavoidable problem in the lithium extraction process from spodumene. Potassium and lithium in the acidic leaching solution of spodumene belong to the same Group I group and have very similar properties, making efficient separation difficult. Potassium will affect the product quality of the lithium hydroxide production line, resulting in excessive potassium in the lithium hydroxide product. Multiple dissolution and recrystallization are required to remove potassium from the lithium hydroxide product, making the lithium hydroxide production line lengthy. At the same time, the presence of potassium will also lead to an increasing accumulation of potassium content in the lithium precipitation mother liquor of the sodium carbonate production line, affecting the recycling of the lithium precipitation mother liquor. Furthermore, the difficulty in separating lithium and potassium severely restricts the flotation process of spodumene. To reduce the negative impact of potassium on lithium extraction, associated minerals with high potassium content, such as mica, are usually suppressed from entering the tailings during the lithium ore flotation stage. This inevitably leads to some valuable spodumene entering the tailings, resulting in lithium loss. It is foreseeable that developing new technologies to solve these two problems will inevitably drive the spodumene lithium extraction industry towards a more environmentally friendly and economical direction.

[0004] Patent CN 114477241 A relates to a method for low-temperature conversion roasting of spodumene assisted by sulfate and alkali compounds to extract lithium. However, this method only achieves a high lithium extraction rate through pressure leaching, which is difficult to promote industrially. Furthermore, this method does not consider improving the spodumene recovery rate from the beneficiation stage. Patent CN 109517981 A relates to a method for extracting lithium from spodumene by grinding and leaching assisted by calcium-containing substances instead of conversion roasting. However, this method also requires high energy consumption during the grinding and leaching process, demands excessively fine particle size of the product after grinding and leaching, and results in high wear of the ball milling media. Simultaneously, this method also requires pressure leaching of the ground and leached product to achieve a high lithium extraction rate, which is difficult to promote industrially. Moreover, this method also does not consider improving the spodumene recovery rate from the beneficiation stage. Wang Chengyan et al. reported a method for alkaline leaching of lithium from a high-potassium mixed lithium concentrate of spodumene and lepidolite. However, this report does not reduce the energy consumption of spodumene conversion, nor does it explore how to remove potassium from the mixed lithium concentrate leachate. Patent CN 102010991 B relates to a method for freezing and precipitating potassium in the form of potassium aluminum sulfate. However, the solubility of potassium aluminum sulfate is significantly affected by temperature, making complete precipitation difficult. Patent CN 113387374 A proposes using iron salts to treat a mixed solution of potassium-containing mother liquor from a lithium carbonate production line and potassium-rich mother liquor from a lithium hydroxide production line. However, this method lacks process coordination, leading to numerous problems such as multiple additions of sulfuric acid, repeated neutralization with alkali, high heat consumption, and a complex process. Furthermore, the potassium removal rate in the mixed solution is only 50%-80%, with some lithium lost in the potassium precipitation. Patent CN 114231741 A relates to a method for removing potassium using phosphate metal complex ions. However, this method requires the additional preparation of a potassium removal precursor, which also has a certain adsorption capacity for lithium, easily causing lithium loss. It is worth noting that none of the above patents (CN 102010991B, CN 113387374 A, CN 114231741 A) address how to coordinate the low recovery rate of spodumene in mineral processing and the high energy consumption of spodumene transformation in metallurgy. Summary of the Invention

[0005] To address the shortcomings of existing lithium extraction processes from spodumene ore, such as low flotation recovery rates, poor lithium-potassium selective separation, and high energy consumption, this invention aims to provide a method for the synergistic lithium extraction of spodumene and mica. This method yields a lithium-containing purified solution with high purity, low impurity content, and high lithium recovery rate. Furthermore, the method is simple, low-cost, and energy-efficient.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a method for synergistic lithium extraction from spodumene and mica, comprising the following steps:

[0007] 1) Flotation of spodumene ore yields spodumene concentrate with a potassium oxide content of 1-5 wt%.

[0008] 2) Spodumene concentrate is mixed with transformation aids and binders to form pellets, which are then roasted to obtain transformed spodumene.

[0009] 3) The transformed spodumene is subjected to an acid leaching reaction to obtain a lithium-potassium leachate;

[0010] 4) The lithium-containing potassium leachate is sequentially added to potassium ferric sulfate seed crystals and ferric sulfate to carry out potassium precipitation reaction. The reaction product is separated by solid-liquid separation to obtain potassium-removed solution and potassium ferric sulfate precipitate.

[0011] 5) The potassium-removing solution is purified by adjusting the pH to obtain a lithium-containing purified solution.

[0012] The key to this invention lies in utilizing the highly selective nucleation of potassium ferric sulfate (KFS) for lithium and potassium ions during its formation process to capture potassium ions in solution, thereby targeting and precipitating potassium as KFS to achieve selective separation of lithium and potassium in solution. By addressing the issue of metallurgical potassium affecting lithium salt extraction, the limitation of mica (potassium) in spodumene flotation concentrate can be reduced. A suitable amount of mica (based on potassium oxide content) is intentionally retained in the concentrate to decrease the loss rate of spodumene during flotation. Furthermore, the fluorine in the mica retained in the lithium concentrate and the added conversion aids can facilitate the breaking of aluminum-oxygen and silicon-oxygen bonds in the spodumene structure during roasting, thus reducing the roasting temperature of spodumene conversion to a certain extent and saving energy. In addition, the KFS precipitate generated during the separation process can be recycled, improving resource utilization.

[0013] The principle of selective lithium-potassium separation in this invention is as follows: Ferrous sulfate compounds (MFe3(SO4)2(OH)6, where M represents NH4+) + H3O + Ag + and except Li + Alkali metal ions (such as those found in lithium sulfate) are stable and poorly soluble substances. In a lithium-potassium sulfuric acid solution system, when a certain amount of potassium ferric sulfate seed crystals are added and the temperature and pH are controlled within a suitable range, potassium reacts rapidly with iron to form potassium ferric sulfate precipitate. However, due to the difference in ionic radii between lithium and potassium, lithium does not precipitate. This achieves targeted precipitation of potassium from the lithium sulfate solution, eliminating the influence of potassium on the extraction of lithium salts from the acidic leaching solution of spodumene. The reaction of potassium precipitation induced by potassium ferric sulfate seed crystals is as follows:

[0014] 3Fe2(SO4)3+K2SO4+12H2O=2KFe3(SO4)2(OH)6(↓)+6H2SO4

[0015] The principle of improving the recovery rate of spodumene in the beneficiation process is as follows: based on the selective separation of lithium and potassium in the metallurgical process, the restriction on the mica (potassium) content of spodumene concentrate in the beneficiation process is appropriately relaxed, and some mica is "deliberately" retained in the spodumene concentrate to reduce the loss of spodumene in the flotation process, thereby solving the problem of insufficient spodumene flotation recovery rate.

[0016] The principle for reducing the energy consumption of spodumene conversion roasting is as follows: During roasting, the conversion aid and the fluorine retained in the mica of the lithium concentrate release monovalent fluorine (F) during the conversion process. - Replace the divalent oxygen in the aluminosilicate structure 2- This process disrupts the aluminum-oxygen and silicon-oxygen bonds in the mineral structure, enabling spodumene to be activated and transformed even under low-temperature calcination. Furthermore, to maintain the mineral's electroneutrality, excess monovalent Li₂ is used... + It will be "squeezed out" of the crystal structure, making lithium easier to leach out with sulfuric acid.

[0017] As a preferred embodiment, the transformation aid includes sodium fluoride and calcium oxide.

[0018] As a preferred embodiment, the amount of sodium fluoride is 5-10 wt% of the spodumene concentrate; the amount of calcium oxide is 10-30 wt% of the spodumene concentrate. When the amount of sodium fluoride or calcium oxide is too low, the structure of α-spodumene cannot be efficiently destroyed, making it difficult to achieve rapid transformation of spodumene; when the amount of sodium fluoride or calcium oxide is too high, it will result in an excessive amount of spodumene tailings and insufficient economic efficiency.

[0019] As a preferred embodiment, the binder is a clay-type mineral. More preferably, the main component of the clay-type mineral is bentonite.

[0020] As a preferred embodiment, the amount of the binder is 1-2 wt% of spodumene concentrate.

[0021] As a preferred embodiment, the pellet size is 5–10 mm. Controlling the pellet size within a suitable range can improve calcination efficiency and promote spodumene transformation. If the pellet size is too small, the material will melt and agglomerate during calcination, while if the pellet size is too large, a longer calcination time will be required to achieve spodumene transformation within each pellet.

[0022] As a preferred embodiment, the calcination reaction conditions are: temperature of 800–900℃ and time of 60–90 min. Controlling the calcination reaction temperature and time within a reasonable range is beneficial to improving calcination efficiency. If the calcination temperature is too low or the time is too short, it will hinder the full transformation of α-type spodumene; if the calcination temperature is too high or the time is too long, it will cause the spodumene concentrate to melt and agglomerate, increasing the energy consumption for spodumene transformation.

[0023] As a preferred embodiment, the particle size of the transformed spodumene is -100 mesh to +325 mesh. Controlling the particle size of the transformed spodumene within a reasonable range is beneficial for improving leaching efficiency, ensuring the purity of the leachate, and reducing energy consumption.

[0024] As a preferred embodiment, in the acid leaching reaction, sulfuric acid is used as the leaching agent, with a concentration of 2–5 mol / L, a liquid-to-solid ratio of 5–10 mL:1 g, a temperature of 70–90 °C, and a time of 60–120 min. Controlling the leaching agent concentration, liquid-to-solid ratio, leaching temperature, and leaching time within a reasonable range during the acid leaching process can improve leaching efficiency and facilitate obtaining a lithium extraction solution with high purity. Too low a leaching agent concentration, too low a liquid-to-solid ratio, too low a leaching temperature, or too short a leaching time will relatively reduce the lithium extraction rate; while too high a sulfuric acid concentration, too high a liquid-to-solid ratio, too high a temperature, or too long a time will lead to an increase in the content of impurity elements in the lithium extraction leachate and will also be uneconomical.

[0025] As a preferred embodiment, the liquid-to-solid ratio of the lithium-containing potassium leachate to the potassium ferrous sulfate seed crystals is 80–60 mL: 1 g. Controlling the amount of potassium ferrous sulfate seed crystals within a suitable range is beneficial to improving potassium precipitation efficiency. If the amount is too low, it will reduce the potassium precipitation rate, making it difficult to effectively lower the temperature required for the potassium precipitation reaction and narrow the pH range of the reaction system; if the amount is too high, it will lead to an increase in the amount of potassium precipitate residue.

[0026] As a preferred embodiment, during the potassium precipitation reaction, the molar ratio of iron in ferric sulfate to potassium in the lithium-containing potassium leachate is controlled to be 4.0–5.0:1.

[0027] As a preferred embodiment, during the potassium precipitation reaction, the pH of the reaction system is controlled at 1.0–2.0, the reaction temperature at 70–90°C, and the reaction time at 40–60 min.

[0028] Controlling the pH, ferric sulfate precipitant dosage, reaction temperature, and reaction time within a reasonable range is beneficial to improving potassium separation efficiency. Specifically, excessively low pH, insufficient ferric sulfate dosage, excessively low reaction temperature, or excessively short reaction time are all detrimental to potassium precipitation. Conversely, excessively high pH can cause added iron to convert into hydroxide precipitates, reducing the efficiency of the potassium precipitation reaction. Excessively high ferric sulfate dosage, excessively high reaction temperature, or excessively long reaction time will all increase the cost of potassium precipitation.

[0029] As a preferred approach, the pH of the reaction system is adjusted before adding ferric sulfate.

[0030] As a preferred embodiment, the potassium content in the potassium removal solution is less than 5 mg / L.

[0031] As a preferred embodiment, the purification and impurity removal process is as follows: first, lime is used to adjust the pH to 5.0-6.0, and solid-liquid separation is performed. Then, sodium carbonate is added to the obtained solution to adjust the pH to 11.0-12.0, and solid-liquid separation is performed to obtain a lithium-containing purified solution.

[0032] In this purification and impurity removal process, lime is first used to adjust the pH to 5.0-6.0 to remove iron and aluminum ions from the solution, and then sodium carbonate is added to adjust the pH to 11.0-12.0 to remove calcium and magnesium ions from the solution.

[0033] As a preferred embodiment, the iron, aluminum, calcium, and magnesium contents in the lithium-containing purified solution are all below 3 mg / L.

[0034] Compared with the prior art, the present invention has the following beneficial technical effects:

[0035] (1) Potassium is precipitated into jaundice iron alum with high stability, good crystallinity and poor solubility by iron salt, so as to achieve high selective separation of lithium and potassium in solution system and solve the problem of potassium in spodumene leachate affecting the purification of lithium salt.

[0036] (2) By improving the flotation recovery rate of spodumene through the synergistic effect of spodumene and mica, the energy consumption of spodumene transformation can be effectively reduced.

[0037] (3) The lithium-containing purified solution obtained by separation has high purity and very low impurity content. It can be directly used to prepare battery-grade lithium hydroxide and lithium carbonate, and has high application value.

[0038] (4) The method is simple, the conditions are mild, the cost is low, and the system is highly adaptable. Attached Figure Description

[0039] Figure 1 This is a process flow diagram of the method for synergistic lithium extraction from spodumene and mica in Example 1 of this application. Detailed Implementation

[0040] The specific embodiments of the present invention will be further illustrated below, but the specific embodiments of the present invention are not limited to the following embodiments.

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments and comparative examples. It should be understood that the specific embodiments and comparative examples described herein are for illustrative purposes only and are not intended to limit the invention.

[0042] Example 1

[0043] Low-precision spodumene concentrate with Li2O and K2O contents of 4.92% and 2.12% respectively was obtained from primary spodumene ore with Li2O and K2O contents of 1.50% and 2.16% respectively by low-precision flotation. The Li2O recovery rate of this concentrate relative to the original spodumene ore was 85.05%. 100g of low-precision spodumene concentrate was taken and mixed with 8% sodium fluoride (8g) and 20% calcium oxide (20g) to prepare spherical materials with a particle size of 5-10mm. The moisture-containing pellets were dried at 100℃ for 120min to remove moisture, and then placed in a muffle furnace for transformation roasting at 850℃ for 60min. After calcination, the calcined material was cooled to 100℃ and ball-milled to below 100 mesh. All the ball-milled fines were then placed in a 1L (4mol / L) sulfuric acid solution at 90℃ and stirred uniformly for 90 minutes. The solution was then filtered to obtain 1L of leachate. 15g of potassium vanadium seed crystals were added to the leachate, along with ferric sulfate at a molar ratio of iron to potassium in the leachate of 4.5. The selective potassium precipitation time was controlled to be 50 minutes. During this process, the leachate temperature was maintained at 75℃, and the pH was maintained between 1.0 and 2.0 using sodium hydroxide and concentrated sulfuric acid. Finally, lime was added sequentially to adjust the pH to 6.0, and sodium carbonate was added to adjust the pH to 12.0 to precipitate iron, aluminum, calcium, and magnesium in the leachate. The purified solution was then obtained after filtration.

[0044] Analysis showed that the lithium leaching rate (relative to the provided low-precision spodumene concentrate) in the purified solution obtained in Example 1 was 95.98%, and the overall lithium extraction rate relative to the original spodumene ore was 81.63%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were only 4.11 mg / L, 1.12 mg / L, 2.03 mg / L, 1.55 mg / L, and 2.31 mg / L, respectively. This indicates that the present technical solution can extract lithium from primary spodumene ore with lower flotation precision and lower energy consumption, effectively removing potassium from the leachate while ensuring the effective precipitation of other impurities.

[0045] Example 2

[0046] The method of Example 1 was used to extract lithium, except that the amount of sodium fluoride added was changed to 10g (10wt% relative to spodumene concentrate), and the transformation roasting temperature was set to 800℃.

[0047] Analysis showed that the lithium leaching rate (relative to the provided low-precision spodumene concentrate) in the purified solution obtained under the conditions of this example was 95.34%, and the overall lithium extraction rate relative to the original spodumene ore was 81.09%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were only 3.27 mg / L, 1.84 mg / L, 2.21 mg / L, 1.73 mg / L, and 1.68 mg / L, respectively. Example 2 achieved a similar lithium extraction rate to Example 1, indicating that increasing the amount of spodumene conversion aid under certain conditions can further reduce the conversion temperature of spodumene.

[0048] Example 3

[0049] Lithium extraction was performed using the method described in Example 1, with the difference that the selective potassium precipitation time was 40 minutes and the selective potassium precipitation temperature was maintained at 90°C.

[0050] Analysis showed that the lithium leaching rate (relative to the provided low-precision spodumene concentrate) in the purified solution obtained under the conditions of this example was 95.98%, and the overall lithium extraction rate relative to the original spodumene ore was 81.63%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were only 2.55 mg / L, 1.34 mg / L, 1.97 mg / L, 1.43 mg / L, and 2.19 mg / L, respectively. Compared with Example 1, Example 2 showed very similar impurity removal effects in the leaching solution, especially in terms of potassium content. This indicates that under certain conditions, increasing the potassium precipitation reaction temperature and shortening the potassium precipitation reaction time can also effectively remove potassium from the leaching solution.

[0051] Example 4

[0052] Lithium extraction was performed using the method described in Example 1, except that the amount of sodium fluoride added was changed to 2g (2wt% relative to spodumene concentrate).

[0053] Analysis revealed that the lithium leaching rate (relative to the provided low-precision spodumene concentrate) in the purified solution obtained under the conditions of this embodiment was 74.52%, and the overall lithium extraction rate relative to the original spodumene ore was 63.46%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were only 3.88 mg / L, 1.24 mg / L, 1.69 mg / L, 2.03 mg / L, and 1.95 mg / L, respectively.

[0054] Compared to Example 1, the lithium leaching rate in the purified solution of this example (relative to the provided low-precision spodumene concentrate) was 21.46 percentage points lower, indicating a decrease in lithium extraction rate. This is mainly attributed to the lower amount of spodumene transformation aid (sodium fluoride) added under these conditions, resulting in the incomplete transformation of α-spodumene into β-spodumene during low-temperature roasting, thus affecting lithium extraction. Furthermore, compared to Example 1, the concentrations of impurity elements (especially potassium) in the purified solution under these conditions were very similar and lower, further confirming that potassium introduced by low-precision flotation can be effectively removed during the potassium precipitation process of jasper ferrous sulfate proposed in this scheme.

[0055] Example 5

[0056] Lithium extraction was performed using the method described in Example 1, except that the conversion roasting temperature was set to 700°C.

[0057] Analysis revealed that the lithium leaching rate (relative to the provided low-precision spodumene concentrate) in the purified solution obtained through this process was 79.48%, and the overall lithium extraction rate relative to the original spodumene ore was 67.60%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were only 3.67 mg / L, 1.65 mg / L, 2.07 mg / L, 1.84 mg / L, and 1.57 mg / L, respectively.

[0058] Compared to Example 1, the lithium leaching rate in the purified solution of this example (relative to the provided low-precision spodumene concentrate) was 16.50 percentage points lower, indicating a decrease in lithium extraction rate. This is mainly attributed to the lower spodumene transformation roasting temperature in this example, which prevented α-spodumene from completely transforming into β-spodumene during the low-temperature roasting process, thus affecting lithium extraction. Furthermore, compared to Example 1, the concentrations of impurity elements (especially potassium) in the purified solution under these conditions were very similar and lower, further confirming that potassium introduced by low-precision flotation can be effectively removed during the potassium precipitation process of jasper ferrous sulfate proposed in this scheme.

[0059] Example 6

[0060] Lithium extraction was performed using the method described in Example 1, except that the amount of potassium ferric sulfate seed crystals added was changed to 5g.

[0061] Analysis showed that the lithium leaching rate (relative to the provided low-precision spodumene concentrate) in the purified solution obtained in this embodiment was 96.12%, and the overall lithium extraction rate relative to the original spodumene ore was 81.75%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were only 185.22 mg / L, 1.79 mg / L, 1.81 mg / L, 1.64 mg / L, and 1.92 mg / L, respectively.

[0062] Compared to Example 1, the lithium leaching rate in the purified solution of this example is similar (relative to the provided low-precision spodumene concentrate), and the overall lithium extraction rate is higher. However, the potassium concentration in the purified solution is 181.11 mg / L higher. This is mainly attributed to the lower amount of jasmine seed crystals used in the potassium precipitation process, which makes it difficult to induce rapid potassium precipitation. At this amount of seed crystals, a longer time and higher temperature are required for potassium to be fully precipitated.

[0063] Comparative Example 1

[0064] The method of Example 1 was used to extract lithium, except that the raw material for lithium extraction was a high-precision spodumene concentrate with Li2O and K2O contents of 5.81% and 0.59%, respectively. The Li2O recovery rate of this concentrate relative to the original spodumene ore was 79.52%.

[0065] Analysis showed that the lithium leaching rate (relative to the provided high-precision spodumene concentrate) in the purified solution obtained in this comparative example was 85.47%, and the overall lithium extraction rate relative to the original spodumene ore was 67.97%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were only 2.85 mg / L, 1.56 mg / L, 1.77 mg / L, 1.48 mg / L, and 1.75 mg / L, respectively.

[0066] Compared to Example 1, the lithium leaching rate in the purified solution of Comparative Example 1 (relative to the provided low-precision spodumene concentrate) was 10.51 percentage points lower. This is mainly attributed to the significantly lower mica content in the high-precision spodumene concentrate compared to the low-precision spodumene concentrate. With the same amount of spodumene conversion aid, the conversion effect of the high-precision spodumene concentrate (Comparative Example 1) is weaker than that of the low-precision spodumene concentrate (Example 1), resulting in a lower lithium leaching rate. Furthermore, the concentrations of impurity elements in the purified solution of Comparative Example 1 were all lower, further confirming that potassium in the spodumene concentrate leaching solution can be effectively removed during the potassium precipitation process of jasper ferrugin proposed in this scheme.

[0067] Comparative Example 2

[0068] High-precision spodumene concentrate with Li2O and K2O contents of 5.81% and 0.59% respectively was obtained from primary spodumene ore with Li2O and K2O contents of 1.50% and 2.16% respectively through high-precision flotation. The Li2O recovery rate of this concentrate relative to the original spodumene ore was 79.52%. 100g of the high-precision spodumene concentrate was prepared into spherical particles with a particle size of 5-10mm, dried at 100℃ for 120min to remove moisture, and then placed in a muffle furnace for transformation roasting at 1050℃ for 60min. After roasting, the roasted material was cooled to 100℃ and ball-milled to below 100 mesh. All the ball-milled fines were then placed in a 4mol / L, 1L sulfuric acid solution at 90℃ and stirred uniformly for 90min. The leachate was then filtered to obtain 1L of leachate. Lime was added to the cooled leachate to adjust the pH to 6.0 and sodium carbonate was added to adjust the pH to 12.0 to precipitate the iron, aluminum, calcium and magnesium in the leachate. The purified solution was then filtered to obtain the purified solution.

[0069] Analysis showed that the lithium leaching rate (relative to the provided high-precision spodumene concentrate) in the purified solution obtained in Comparative Example 2 was 93.33%, and the overall lithium extraction rate relative to the original spodumene ore was 74.22%. Furthermore, the contents of potassium, iron, aluminum, calcium, and magnesium in the purified solution were 476.25 mg / L, 1.56 mg / L, 1.98 mg / L, 2.46 mg / L, and 1.77 mg / L, respectively.

[0070] Compared with Example 1, Comparative Example 2 showed a similar lithium leaching rate in the purified solution (relative to the provided high-precision spodumene concentrate), indicating that high-temperature roasting is required to achieve efficient lithium extraction without the addition of conversion aids, which inevitably leads to higher energy consumption. In addition, in Comparative Example 2, high-precision flotation was used to avoid excessive potassium entering the concentrate, and the lithium recovery rate of the spodumene concentrate relative to the primary spodumene was only 79.52%, which is 5.53 percentage points lower than the flotation recovery rate of the low-precision spodumene concentrate in Example 1. Combining the flotation and metallurgical stages, the lithium extraction rate of Comparative Example 2 was 7.41 percentage points lower than that of Example 1. Regarding the impurity element content of the purified solution, the potassium concentration in the purified solution of Comparative Example 2 was 472.14 mg / L higher than that of Example 1, while the contents of other impurity elements were similar. This indicates that although Comparative Example 2 used high-precision flotation, resulting in a lower potassium content in the spodumene concentrate than in Example 1, the final potassium concentration in the purified solution was significantly higher. This demonstrates that even if low-precision flotation introduces a large amount of potassium into the spodumene concentrate, the potassium in the lithium leaching solution can still be effectively removed through the potassium removal process induced by jaundice crystal seeding.

[0071] Comparative Example 2 represents the traditional "high-precision flotation-sulfuric acid process" for lithium extraction from spodumene ore. Compared with this, the technical solution of the present invention (Example 1) has three major advantages: higher lithium extraction rate, lower energy consumption for transformation roasting, and lower potassium content in the purification liquid. This shows that the technical solution can lay a solid foundation for low-energy and high-efficiency extraction of lithium from primary spodumene ore and has certain prospects for industrial promotion.

Claims

1. A method for synergistic lithium extraction from spodumene and mica, characterized in that: Includes the following steps: 1) Flotation is performed on spodumene ore to obtain spodumene concentrate with a potassium oxide content of 1~5wt%; 2) Spodumene concentrate is mixed with transformation aids and binders to form pellets, which are then roasted to obtain transformed spodumene. 3) The transformed spodumene is subjected to an acid leaching reaction to obtain a lithium-potassium leachate; 4) The lithium-containing potassium leachate was sequentially added to potassium ferric sulfate seed crystals and ferric sulfate to carry out a potassium precipitation reaction. The reaction product was separated by solid-liquid separation to obtain a potassium-removed solution and potassium ferric sulfate precipitate. 5) The potassium-removing solution is purified by adjusting the pH to obtain a lithium-containing purified solution; The transformation aid comprises sodium fluoride and calcium oxide; the amount of sodium fluoride is 5-10 wt% of spodumene concentrate; the amount of calcium oxide is 10-30 wt% of spodumene concentrate. The conditions for the calcination reaction are: temperature of 800~900℃ and time of 60~90min; The liquid-solid ratio of the lithium-containing potassium leachate to the potassium ferrous sulfate seed crystals is 80-60 mL: 1 g.

2. The method for synergistic lithium extraction from spodumene and mica according to claim 1, characterized in that: The binder is a clay mineral; the amount of the binder is 1-2 wt% of spodumene concentrate.

3. The method for synergistic lithium extraction from spodumene and mica according to claim 1, characterized in that: The pellet size is 5~10mm.

4. The method for synergistic lithium extraction from spodumene and mica according to claim 1, characterized in that: In the acid leaching reaction, sulfuric acid is used as the leaching agent, with a sulfuric acid concentration of 2-5 mol / L, a liquid-to-solid ratio of 5-10 mL:1 g, a temperature of 70-90℃, and a time of 60-120 min.

5. The method for synergistic lithium extraction from spodumene and mica according to claim 1, characterized in that: During the potassium precipitation reaction, the molar ratio of iron in ferric sulfate to potassium in the lithium-containing potassium leachate is controlled at 4.0~5.0:1; the pH of the reaction system is controlled at 1.0~2.0, the reaction temperature at 70~90℃, and the reaction time at 40~60min.

6. The method for synergistic lithium extraction from spodumene and mica according to claim 1, characterized in that: The purification and impurity removal process is as follows: First, lime is used to adjust the pH to 5.0~6.0, and solid-liquid separation is performed. Then, sodium carbonate is added to the obtained solution to adjust the pH to 11.0~12.0, and solid-liquid separation is performed to obtain a lithium-containing purified solution.

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