A method for efficiently extracting lithium from lepidolite by sulfonate complex low-temperature strengthening roasting and application thereof

Abstract

The present application relates to a kind of sulfonate complex low temperature strengthening calcination method for efficiently extracting lithium from lepidolite and application.A kind of sulfonate complex low temperature strengthening calcination method for efficiently extracting lithium from lepidolite, comprising the following steps: pre-activation treatment to lepidolite concentrate, obtain the activated lepidolite concentrate powder;Lepidolite concentrate powder is mixed with composite calcining agent, then under the condition of temperature less than 300 DEG C acidification calcination, obtain calcination product;Water is added to calcination product and leaching, obtain lithium-containing leaching solution;The composite calcining agent is the mixture of acid and sulfonate.The present application also provides the application of the remaining filtrate after lithium precipitation obtained by the method described in the present application, and the remaining filtrate after lithium precipitation is applied as plant foliage fertilizer after treatment.The present application solves the problem of high operating temperature in the existing lepidolite lithium extraction method, and also solves the problems of environmental pollution and high cost in the existing lepidolite lithium extraction method.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction technology from ores, specifically to a method and application for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite. Background Technology

[0002] Lepidolite, as an important lithium resource, is one of the key raw materials for the preparation of battery-grade lithium carbonate. With the rapid development of new energy technologies, the demand for battery-grade lithium carbonate is increasing daily; therefore, efficient lithium extraction technology from lepidolite has become a research hotspot. Currently, lepidolite lithium extraction processes mainly include pressure cooking, chloride roasting, sulfate roasting, and lithium carbonate roasting (limestone method), among others. Yichun, Jiangxi Province, leveraging its abundant lepidolite resources, has, through years of technological accumulation and development, formed a lepidolite lithium extraction process system primarily based on sulfate roasting.

[0003] Although lithium extraction technologies from lepidolite are showing a diversified development trend, each method has certain limitations. For example, while chloride roasting can process lepidolite ore of different grades, it consumes a large amount of auxiliary materials, operates at high temperatures, and generates serious environmental pollution during production. Pressure leaching, while achieving high-efficiency lithium extraction, requires extremely sophisticated equipment, incurs high initial investment costs, and also causes environmental pollution during production. Calcium carbonate roasting (limestone method), although relatively simple in process, consumes a large amount of auxiliary materials, operates at high temperatures, and is prone to caking during roasting, leading to increased costs. Sulfate roasting, currently the mainstream process for lithium extraction from lepidolite, while offering high lithium extraction efficiency, also faces challenges such as high operating temperatures, large auxiliary material consumption, and difficulties in achieving profitability. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a method and application for high-efficiency lithium extraction from lepidolite by low-temperature enhanced roasting with sulfonate compound, so as to solve the problem of high operating temperature in existing lepidolite lithium extraction methods, as well as the problems of environmental pollution and high cost in existing lepidolite lithium extraction methods.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for efficient lithium extraction from sulfonate compound low-temperature enhanced calcination lepidolite includes the following steps:

[0007] S1. Pre-activation treatment of lepidolite concentrate to obtain activated lepidolite concentrate powder;

[0008] S2. Mix lepidolite concentrate powder with composite roasting agent, and then acid-roast at a temperature below 300 ℃ to obtain roasted product;

[0009] S3. Add water to the calcined product and leach to obtain a lithium-containing leachate;

[0010] The composite calcining agent is a mixture of acid and sulfonate.

[0011] Based on the aforementioned technical methods, the synergistic use of aminosulfonate and sulfuric acid for lithium extraction effectively enhances acid stability and lithium selectivity. Compared to the sulfuric acid method alone, it significantly improves the lithium conversion rate in lepidolite while simultaneously reducing roasting temperature and saving energy. This solves the problem of high operating temperatures in existing lepidolite lithium extraction methods. Furthermore, the leached solution is rich in nitrogen and potassium, making it suitable for use as a foliar fertilizer, achieving a closed loop of "recycling equals added value." While the sulfuric acid method alone is highly adaptable to raw materials, it generates a large amount of waste residue. The addition of aminosulfonate reduces the amount of residue and environmental pollution, thus addressing the environmental pollution and high cost issues of existing lepidolite lithium extraction methods. Through process optimization and impurity removal technology, the processing efficiency and product quality of lepidolite concentrate are further improved, promoting the efficient and environmentally friendly development and utilization of lithium resources. This is of great significance to the sustainable development of the lithium industry and has application value in the field of ore lithium extraction technology.

[0012] The principle of the synergistic effect between aminosulfonates and sulfuric acid is analyzed as follows:

[0013] 1) Synergistic enhancement of acidic environment: Sulfuric acid provides SO4 2- The ions undergo ion exchange with lithium ions to form soluble lithium sulfate. During the hydrolysis of aminosulfonates, H+ is generated. + and the H provided by sulfuric acid + Together, they promote the decomposition of the lepidolite structure, making it easier for lithium ions to be released and improving the conversion rate of metal ions in lepidolite.

[0014] 2) Lowering the calcination temperature: Sulfuric acid (H2SO4), as a strong acid, can destroy the crystal structure of metal compounds, providing a large amount of H+. + This process displaces metal ions from lepidolite, forming stable complexes. Meanwhile, the hydrolysis products of aminosulfonates (such as NH4SO4) - It can also combine with metal ions to form soluble salts or complexes. Sulfuric acid and aminosulfonates work synergistically to reduce the activity of metal ions, further increasing the reaction rate. Therefore, the temperature required for acid roasting can be lowered, thereby reducing energy consumption and improving reaction efficiency.

[0015] 3) Optimizing the roasting environment and reducing side reactions: The addition of aminosulfonates can reduce the decomposition of sulfuric acid at high temperatures and reduce the escape of SO3 gas, thereby improving the safety and stability of the roasting process. Compared with sulfuric acid, aminosulfonic acid itself has the characteristics of good stability and low toxicity. The synergistic effect of sulfuric acid and aminosulfonates can reduce the formation of by-products such as HF, thereby improving the purity and recovery rate of lithium.

[0016] In summary, the synergistic effect of aminosulfonates and sulfuric acid is mainly achieved by enhancing the acidic environment, lowering the roasting temperature, optimizing the roasting environment, and reducing side reactions. These mechanisms work together to significantly improve lithium conversion, enhance the stability of the acid system, and reduce environmental pollution.

[0017] Preferably, the pre-activation treatment involves placing the lepidolite concentrate in an air jet mill, controlling the airflow velocity to be 300-500 m / s, the nozzle pressure to be 0.8-1.2 MPa, the classifier wheel speed to be 3000-5000 rpm, and the feeding speed to be 50-200 kg / h, in order to achieve pre-activation of the lepidolite concentrate.

[0018] By pre-activating lepidolite concentrate using an air jet mill, the high-speed airflow (300~500 m / s) in the air jet mill causes the particles to collide, shear, and rub at high speeds to achieve pulverization. At the same time, the crystal structure of lepidolite undergoes the following changes: 1) Increased lattice distortion and defects: The strong mechanical force causes the layered structure of lepidolite to break, generating a large number of defects, dislocations, and amorphous regions in the lattice, thereby exposing more active sites and enhancing chemical reactivity; 2) Increased specific surface area: The particles are ultra-fine, the particle size is significantly reduced, and the specific surface area is increased, improving the contact efficiency during subsequent reactions (such as acid leaching). At the same time, the surface atomic arrangement becomes disordered, further increasing the number of active sites; 3) Increased internal energy: Mechanical energy is converted into lattice internal energy, the local temperature increases, and the activation energy required for subsequent reactions is reduced, which is beneficial for lithium dissolution. 4) Phase Transformation: Under the impact and shearing action of airflow, some lepidolite crystal structures can transform from a stable state to a metastable state, and even exhibit localized amorphization, effectively promoting phase transformation reactions in subsequent roasting or leaching processes. In summary, the pre-activation of the airflow mill not only achieves the physical pulverization of lepidolite concentrate, but also provides more favorable reaction conditions for efficient lithium extraction (such as roasting transformation or leaching) through high-energy mechanical force-induced crystal structure destruction and surface activation.

[0019] Among them, air jet mills utilize high-speed airflow to pulverize material particles through inter-particle collisions and frictional shearing. This process is accompanied by the following activation effects: particle miniaturization significantly increases the specific surface area and causes disordered surface atomic arrangement, thereby increasing active sites; rapid impact can disrupt the periodicity of mineral crystal structure, generating lattice defects (such as dislocations and vacancies), thereby enhancing chemical reactivity; when compressed air is released through Laval nozzles, due to the adiabatic expansion effect, the temperature inside the pulverizing chamber usually does not rise significantly, and is generally controlled below 30°C.

[0020] Preferably, the chemical composition and mass percentage of the lepidolite concentrate are as follows: Li₂O 2.3%, SiO₂ 45.7%, Al₂O₃ 21.1%, K₂O 8.1%, Na₂O 4.9%, F 4.6%, CaO 3.1%, Fe₂O₃ 1.3%, Rb₂O 0.4%, Cs₂O 0.1%, with the remainder being other impurities.

[0021] Preferably, the sulfonate is selected from one or both of ammonium aminosulfonate and sodium aminosulfonate;

[0022] The acid is selected from concentrated sulfuric acid.

[0023] Preferably, when the sulfonate is selected from ammonium aminosulfonate, the mass ratio of the lepidolite concentrate powder, concentrated sulfuric acid and ammonium aminosulfonate is 1:0.6~0.8:0.2~0.5.

[0024] Preferably, when the sulfonate is selected from sodium aminosulfonate, the mass ratio of the lepidolite concentrate powder, concentrated sulfuric acid and sodium aminosulfonate is 1:0.6~0.8:0.3~0.6.

[0025] Preferably, the sulfonate is selected from ammonium aminosulfonate and sodium aminosulfonate;

[0026] The concentration of sulfonate solution is 150~200 g / L;

[0027] The mass ratio of the lepidolite concentrate powder, concentrated sulfuric acid, ammonium aminosulfonate, and sodium aminosulfonate is 1:0.6~0.8:0.2~0.5:0.3~0.6.

[0028] Preferably, the acidification and roasting temperature is 130–300 °C.

[0029] Preferably, the acidification and roasting temperature is 60-90 min.

[0030] Preferably, the temperature for water immersion is 90~99 ℃.

[0031] Preferably, the soaking time is 60-90 minutes.

[0032] Preferably, the mass ratio of the roasted product to water is 1:3~5.

[0033] Preferably, it further includes:

[0034] S4. The lithium-containing leachate is passed through a precipitant to remove aluminum / fluorine impurities, resulting in a purified lithium-containing leachate.

[0035] S5. Evaporate and concentrate the lithium-containing leachate after impurity removal, then add a lithium precipitation agent to carry out a lithium precipitation reaction at room temperature and pressure, filter, and obtain lithium precipitate product and residual filtrate after lithium precipitation.

[0036] Preferably, the volume of the evaporated and concentrated solution is 1 / 4 of the volume of the lithium-containing leachate after impurity removal.

[0037] Preferably, the precipitant is selected from at least one of calcium hydroxide, magnesium hydroxide, barium hydroxide, and manganese hydroxide.

[0038] Preferably, the precipitant is selected from calcium hydroxide.

[0039] Preferably, the method of removing aluminum / fluorine impurities by using a precipitant is as follows: by adding a precipitant to the lithium-containing leachate to adjust the pH value of the lithium-containing leachate to above 12, the aluminum / fluorine impurities are removed.

[0040] Preferably, the lithium precipitation agent is selected from sodium dihydrogen phosphate, and the amount of sodium dihydrogen phosphate used is more than 4 times the mass of Li2O in the lithium-containing leachate after impurity removal.

[0041] The present invention also provides an application of the residual filtrate after lithium precipitation obtained by the method described in the present invention, wherein the residual filtrate after lithium precipitation is treated and applied as a foliar fertilizer for plants.

[0042] Preferably, the treatment method includes: treating the remaining filtrate after lithium precipitation and then applying it as a foliar fertilizer for plants.

[0043] Preferably, the treatment method specifically includes: adding a chelating agent to the remaining filtrate after lithium precipitation, and carrying out a chelation reaction at a temperature of 40~45 ℃ to obtain a chelated solution;

[0044] The chelating solution, auxiliary agent, and wetting agent are mixed and compounded, then filtered to obtain the compound filtrate.

[0045] The compound filtrate was diluted and the pH was adjusted to 5.5-6.5 to obtain a nutrient solution that can be used as a complete foliar fertilizer.

[0046] Preferably, the composition of the remaining filtrate after lithium precipitation includes: 0.1 g / L Li, 0.8 g / L Rb, 0.1 g / L Cs, 3.0 g / L Na, 2.8 g / L K, 0.01 g / L Al, 1.9 g / L Si, 0.5 g / L Ca, 0.3 g / L Mg, 0.01 g / L F, 5.0 g / L N, 2.0 g / L P, 2.1 g / L S, and 2.1 g / L organic matter. Other heavy metals (such as mercury, arsenic, cadmium, lead, and chromium) are all below the implementation standard of GB / T 17419-2018 "Follicular Fertilizers Containing Organic Matter".

[0047] Preferably, the chelating agent is selected from one or both of EDTA (ethylenediaminetetraacetic acid) and citric acid.

[0048] Preferably, the chelating agent in the chelating solution has a mass percentage content of 0.1% to 0.3%.

[0049] Preferably, the adjuvant is selected from one or both of agricultural organosilicon and SDS (sodium dodecyl sulfate).

[0050] Preferably, the mass percentage of agricultural organosilicon in the compound filtrate is 0.02~0.06%.

[0051] Preferably, the mass percentage of agricultural organosilicon in the compound filtrate is 0.04%.

[0052] Preferably, the mass percentage of SDS in the compound filtrate is 0.02~0.06%.

[0053] Preferably, the wetting agent is selected from at least one of triethanolamine, glycerin, and urea.

[0054] Preferably, the mass percentage of triethanolamine in the compound filtrate is 0.02~0.06%.

[0055] Preferably, the mass percentage of glycerol in the compound filtrate is 0.02~0.06%.

[0056] Preferably, the mass percentage of urea in the compound filtrate is 0.02~0.06%.

[0057] Preferably, the filtration process involves pre-filtration with a 1-5 μm filter membrane followed by fine filtration with a 0.45 μm filter membrane.

[0058] Preferably, the dilution factor of the compound filtrate is determined according to the ion concentration in the compound filtrate, and the concentration of all individual ions is required to be less than 0.5 g / L.

[0059] Preferably, humic acid is used to adjust the diluted liquid of the compound filtrate to maintain the stability of the nutrient solution pH, thereby promoting nutrient absorption.

[0060] Preferably, the nutrient solution, which is a complete foliar fertilizer, can be safely used as a complete foliar fertilizer for lithium-rich crops, silicon-requiring crops, salt-tolerant crops, and micro-potassium-loving crops, so as to achieve the dual goals of industrial waste liquid resource utilization and agricultural quality improvement and efficiency enhancement.

[0061] Among them, the lithium-rich crop is sunflower, the silicon-requiring crop is rice, the salt-tolerant crop is seawater rice, and the micropotassium-loving crop is potato.

[0062] The beneficial effects of this invention are:

[0063] This invention discloses a method for high-efficiency lithium extraction from lepidolite using a low-temperature enhanced roasting process with sulfonate compounding. First, the lepidolite concentrate is pre-activated using an air jet mill. This process involves high-speed particle collision, shearing, and friction within the mill, simultaneously disrupting the lepidolite crystal structure and activating its surface. This provides more favorable reaction conditions for subsequent efficient lithium extraction (such as roasting or leaching). Then, aminosulfonate and sulfuric acid are used synergistically for lithium extraction, effectively enhancing acid stability and lithium selectivity. Compared to the sulfuric acid method alone, this method significantly improves the lithium conversion rate from lepidolite while reducing the roasting temperature and saving energy. Furthermore, while the sulfuric acid method alone is highly adaptable to raw materials, it generates a large amount of waste residue. The addition of aminosulfonate effectively reduces the amount of residue and environmental pollution, which is of great significance for the sustainable development of the lithium industry and has significant application value in the field of ore-based lithium extraction technology.

[0064] The present invention discloses a method for high-efficiency lithium extraction from lithium mica by low-temperature enhanced roasting of sulfonate compound. The remaining filtrate after lithium precipitation is rich in nitrogen and potassium elements. Therefore, after synergistic treatment with chelating agents, adjuvants, wetting agents and pH adjusters, the remaining filtrate after lithium precipitation can be used as a complete nutrient foliar fertilizer, effectively realizing a closed loop of "recycling equals added value". It has promotion and application value in the field of resource recycling technology. Detailed Implementation

[0065] The following description, with reference to preferred embodiments, illustrates the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are merely illustrative of the present invention and not intended to limit the scope of protection of the present invention.

[0066] Where specific techniques or conditions are not specified in the detailed embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0067] In the following examples, the chemical composition and mass percentage of the lepidolite concentrate used are as follows: Li2O 2.3%, SiO2 45.7%, Al2O3 21.1%, K2O 8.1%, Na2O 4.9%, F 4.6%, CaO 3.1%, Fe2O3 1.3%, Rb2O 0.4%, Cs2O 0.1%, with the remainder being other impurities.

[0068] Example 1

[0069] A method for efficient lithium extraction from sulfonate compound low-temperature enhanced calcination lepidolite includes the following steps:

[0070] S1. Add 1000 g of lepidolite concentrate to an air jet mill, control the airflow speed to be 350 m / s, the nozzle pressure to be 0.8 MPa, the classifier wheel speed to be 3000 rpm, and the feeding speed to be 50 kg / h, to obtain activated lepidolite concentrate powder.

[0071] S2. The lithium mica concentrate powder obtained in S1 is mixed with the composite roasting agent, and then placed in a roasting furnace at a temperature of 150 ℃ for acid roasting for 60 min to obtain the roasting product; wherein, the composite roasting agent includes 98% concentrated sulfuric acid and sodium aminosulfonate; the mass ratio of lithium mica concentrate powder, 98% concentrated sulfuric acid and sodium aminosulfonate is 1:0.6:0.5; the sodium aminosulfonate is added by dissolving sodium aminosulfonate in water to form a sodium aminosulfonate solution with a concentration of 150 g / L, and then adding it in solution form;

[0072] S3. The roasted product obtained in S2 is mixed with pure water at a mass ratio of 1:5, and then stirred and leached for 60 min under a water bath at a temperature of 90 ℃. The mixture is then filtered to obtain a lithium-containing leachate and a leaching residue.

[0073] S4. Add Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities with the precipitant and obtain the lithium-containing leachate after impurity removal.

[0074] S5. Evaporate and concentrate the lithium-containing leachate after impurity removal by 4 times, then add 92 g of sodium dihydrogen phosphate lithium precipitation agent to carry out lithium precipitation reaction, and filter to obtain lithium precipitate product and the remaining filtrate after lithium precipitation.

[0075] Example 2

[0076] A method for efficient lithium extraction from sulfonate compound low-temperature enhanced calcination lepidolite includes the following steps:

[0077] S1. Add 1000 g of lepidolite concentrate to an air jet mill, control the airflow speed to be 300 m / s, the nozzle pressure to be 0.9 MPa, the classifier wheel speed to be 3200 rpm, and the feeding speed to be 60 kg / h, to obtain activated lepidolite concentrate powder.

[0078] S2. The lepidolite concentrate powder obtained in S1 is mixed with the composite roasting agent, and then placed in a roasting furnace at a temperature of 150 ℃ for acid roasting for 60 min to obtain the roasting product; wherein, the composite roasting agent includes 98% concentrated sulfuric acid and ammonium aminosulfonate; the mass ratio of lepidolite concentrate powder, 98% concentrated sulfuric acid and ammonium aminosulfonate is 1:0.6:0.5; the ammonium aminosulfonate is added by dissolving ammonium aminosulfonate in water to form an ammonium aminosulfonate solution with a concentration of 200 g / L, and then adding it in solution form;

[0079] S3. The roasted product obtained in S2 is mixed with pure water at a mass ratio of 1:5, and then stirred and leached for 60 min under a water bath at a temperature of 95 ℃. After filtration, lithium-containing leachate and leaching residue are obtained.

[0080] S4. Add Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities with the precipitant and obtain the lithium-containing leachate after impurity removal.

[0081] S5. Evaporate and concentrate the lithium-containing leachate after impurity removal by 4 times, then add 95 g of sodium dihydrogen phosphate lithium precipitation agent to carry out lithium precipitation reaction, and filter to obtain lithium precipitate product and the remaining filtrate after lithium precipitation.

[0082] Example 3

[0083] A method for efficient lithium extraction from sulfonate compound low-temperature enhanced calcination lepidolite includes the following steps:

[0084] S1. Add 1000 g of lepidolite concentrate to an air jet mill, control the airflow speed to be 300 m / s, the nozzle pressure to be 0.9 MPa, the classifier wheel speed to be 3500 rpm, and the feeding speed to be 50 kg / h, to obtain activated lepidolite concentrate powder.

[0085] S2. The lepidolite concentrate powder obtained in S1 is mixed with the composite roasting agent, and then placed in a roasting furnace at a temperature of 180 ℃ for acid roasting for 90 min to obtain the roasting product. The composite roasting agent includes 98% concentrated sulfuric acid, ammonium aminosulfonate, and sodium aminosulfonate. The mass ratio of lepidolite concentrate powder, 98% concentrated sulfuric acid, ammonium aminosulfonate, and sodium aminosulfonate is 1:0.6:0.2:0.3. The ammonium aminosulfonate and sodium aminosulfonate are added by dissolving them in water to form an aminosulfonate solution with a total concentration of 200 g / L, and then adding them in solution form.

[0086] S3. The roasted product obtained in S2 is mixed with pure water at a mass ratio of 1:5, and then stirred and leached for 90 min under a water bath at a temperature of 95 ℃. After filtration, lithium-containing leachate and leaching residue are obtained.

[0087] S4. Add Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities with the precipitant and obtain the lithium-containing leachate after impurity removal.

[0088] S5. The lithium-containing leachate after impurity removal is evaporated and concentrated 4 times, and then 103 g of sodium dihydrogen phosphate lithium precipitation agent is added to carry out the lithium precipitation reaction. The lithium precipitate product and the remaining filtrate after lithium precipitation are obtained by filtration.

[0089] Example 4

[0090] A method for treating the remaining filtrate obtained after lithium precipitation in step S5 of Example 1 and applying it as a foliar fertilizer for plants includes the following steps:

[0091] S1. Add chelating agent EDTA to the remaining filtrate after lithium precipitation, and carry out a chelation reaction at a temperature of 40~45 ℃ to obtain a chelated solution; the mass percentage of EDTA in the chelated solution is 0.2%;

[0092] S2. The chelating solution, agricultural organosilicon adjuvant, and glycerol wetting agent from S1 are mixed and compounded. The mixture is then pre-filtered through a 1-5 μm filter membrane, followed by fine filtration through a 0.45 μm filter membrane to obtain the compounded solution. The mass percentage of both agricultural organosilicon and glycerol in the compounded solution is 0.04%.

[0093] S3. The concentration of the compound solution obtained in S2 is determined based on the ion concentration in the compound filtrate. It is required that the concentration of all single ions is less than 0.5 g / L. Then, the pH value is adjusted to 6.0 with humic acid to maintain pH stability and promote nutrient absorption, thus obtaining a nutrient solution as a complete foliar fertilizer.

[0094] Comparative Example 1

[0095] A method for efficient lithium extraction from sulfonate compound low-temperature enhanced calcination lepidolite includes the following steps:

[0096] S1. Mix 1000 g of lithium mica concentrate powder with a composite roasting agent, and then place it in a roasting furnace at 180 ℃ for acid roasting for 90 min to obtain the roasting product; wherein, the composite roasting agent includes 98% concentrated sulfuric acid, ammonium aminosulfonate and sodium aminosulfonate; the mass ratio of lithium mica concentrate powder, 98% concentrated sulfuric acid, sodium aminosulfonate and ammonium aminosulfonate is 1:0.6:0.2:0.3; the sodium aminosulfonate and ammonium aminosulfonate are added by dissolving sodium aminosulfonate and ammonium aminosulfonate in water to form an aminosulfonate solution with a total concentration of 200 g / L, and then adding it in solution form;

[0097] S3. The roasted product obtained in S2 is mixed with pure water at a mass ratio of 1:5, and then stirred and leached for 90 min under a water bath at a temperature of 95 ℃. After filtration, lithium-containing leachate and leaching residue are obtained.

[0098] S4. Add Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities with the precipitant and obtain the lithium-containing leachate after impurity removal.

[0099] S5. The lithium-containing leachate after impurity removal is evaporated and concentrated 4 times, and then 92 g of sodium dihydrogen phosphate lithium precipitation agent is added to carry out the lithium precipitation reaction. The lithium precipitate product and filtrate are obtained by filtration.

[0100] Comparative Example 2

[0101] A method for efficient lithium extraction from sulfonate compound low-temperature enhanced calcination lepidolite includes the following steps:

[0102] S1. Add 1000 g of lepidolite concentrate to an air jet mill, control the airflow speed to be 300 m / s, the nozzle pressure to be 0.9 MPa, the classifier wheel speed to be 3500 rpm, and the feeding speed to be 50 kg / h, to obtain activated lepidolite concentrate powder.

[0103] S2. The lepidolite concentrate powder obtained in S1 is mixed with 98% concentrated sulfuric acid, and then placed in a roasting furnace at 180 ℃ for acid roasting for 90 min to obtain the roasting product; wherein, the mass ratio of lepidolite concentrate powder to 98% concentrated sulfuric acid is 1:0.8.

[0104] S3. The roasted product obtained in S2 is mixed with pure water at a mass ratio of 1:4, and then stirred and leached for 90 min under a water bath at a temperature of 95 ℃. After filtration, lithium-containing leachate and leaching residue are obtained.

[0105] S4. Add Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities with the precipitant and obtain the lithium-containing leachate after impurity removal.

[0106] S5. Evaporate and concentrate the lithium-containing leachate after impurity removal by 4 times, then add 95 g of sodium dihydrogen phosphate lithium precipitation agent to carry out lithium precipitation reaction, and filter to obtain lithium precipitate product and filtrate.

[0107] Comparative Example 3

[0108] The traditional lithium extraction process using lepidolite and sulfuric acid at high temperature includes the following steps:

[0109] S1. Mix 1000 g of lepidolite concentrate powder with 98% concentrated sulfuric acid, and then place it in a roasting furnace at 900 ℃ for acid roasting for 150 min to obtain the roasting product; wherein, the mass ratio of lepidolite concentrate powder to 98% concentrated sulfuric acid is 1:0.8.

[0110] S3. The roasted product obtained in S2 is mixed with pure water at a mass ratio of 1:4, and then stirred and leached for 90 min under a water bath at a temperature of 95 ℃. After filtration, lithium-containing leachate and leaching residue are obtained.

[0111] S4. Add Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities with the precipitant and obtain the lithium-containing leachate after impurity removal.

[0112] S5. The lithium-containing leachate after impurity removal is evaporated and concentrated 4 times, and then 103 g of sodium dihydrogen phosphate lithium precipitation agent is added to carry out the lithium precipitation reaction. The lithium precipitate product and filtrate are obtained by filtration.

[0113] Detection and Analysis

[0114] 1) Determination of Li2O content in leaching residue, pH value of lithium-containing leachate, yield of leaching residue, and leaching rate of Li2O in lithium mica concentrate.

[0115] The formula for calculating the Li₂O leaching rate in lepidolite concentrate is: Lithium leaching rate = [Leaching liquid volume (L) * Lithium oxide concentration in leaching liquid (g / L)] / [Lithium oxide content in lepidolite concentrate (%) * Mass of lepidolite concentrate (g)] * 100%

[0116] Leaching residue yield (%) = [100% × dry weight of leaching residue (g)] / dry weight of lepidolite concentrate (g)

[0117] The results are shown in Table 1.

[0118] Table 1 shows the determination results of lithium-containing leaching solution and leaching residue.

[0119]

[0120] As can be seen from the analysis in Table 1, by first activating the lithium mica concentrate with an air jet mill, and then using 98% concentrated sulfuric acid and one or a mixture of ammonium aminosulfonate and sodium aminosulfonate as a composite roasting agent, and then carrying out the leaching reaction, the leaching rate of Li2O can be above 90%. Comparing Example 3 and Comparative Example 1, it can be seen that when the lepidolite concentrate is pre-activated using an air jet mill, the leaching rate of Li2O in the leachate is increased by 11.92% compared to the unactivated version; the yield of lithium slag is reduced by 7.13%. Comparing Example 3 and Comparative Example 2, it can be seen that when a composite roasting agent of 98% concentrated sulfuric acid and sulfonate is used, the leaching rate of Li2O in the leachate is increased by 13.97% compared to using 98% concentrated sulfuric acid alone as the roasting agent; the yield of lithium slag is reduced by 20.54%. Comparing Example 3 and Comparative Example 3, it can be seen that when the lepidolite concentrate is pre-activated using an air jet mill and a composite roasting agent of 98% concentrated sulfuric acid and sulfonate is used, the leaching rate of Li2O in the leachate is increased by 22.84% compared to the traditional sulfuric acid 900℃ high-temperature roasting process; the yield of lithium slag is reduced by 22.25%. This demonstrates that the novel low-temperature roasting process using sulfonate compounding significantly improves the leaching rate of Li2O, reduces the amount of slag, and enables the conversion of lithium in lepidolite at lower temperatures, saving energy and reducing production costs.

[0121] 2) Determination of the composition and content of the remaining filtrate after lithium precipitation

[0122] The composition and content of the remaining filtrate after lithium precipitation obtained in S5 of Example 1 were determined by inductively coupled plasma optical emission spectrometry (ICP-OES), atomic absorption spectrometry (AAS), ion chromatography (IC), and elemental analysis (CHNS mode). The results are shown in Table 2.

[0123] Table 2. Results of composition and content determination of residual filtrate after lithium precipitation

[0124]

[0125] According to the national standard GB / T 17419-2018, the requirements, test methods, inspection rules, marking, packaging, transportation, and storage of foliar fertilizers containing organic matter are specified. This standard applies to water-soluble fertilizers containing organic matter, including both liquid and solid forms. Comparison with national standard GB / T 17419-2018:

[0126] 1. Macro-element analysis

[0127] Nitrogen (N): 5.0 g / L, which is a medium concentration and suitable for supplementing the nitrogen required for crop growth, promoting the growth of leaves and stems.

[0128] Phosphorus (P): 2.0 g / L. Phosphorus is an important element for plant growth, which helps root development and flower and fruit formation.

[0129] Potassium (K): 2.8 g / L. Potassium can enhance the stress resistance of crops and the quality of fruits.

[0130] Sulfur (S): 2.1 g / L. Sulfur is an essential medium element for plants and helps to improve the taste and aroma of crops.

[0131] 2. Medium element analysis

[0132] Calcium (Ca): 0.5 g / L. Calcium helps in the formation of cell walls and enhances the disease resistance of crops.

[0133] Magnesium (Mg): 0.3 g / L. Magnesium is a key element in chlorophyll synthesis and promotes photosynthesis.

[0134] Silicon (Si): 1.9 g / L. Silicon can enhance the lodging resistance and disease resistance of crops.

[0135] Aluminum (Al): 0.01 g / L. Aluminum plays a regulatory role in some crops, but excessive amounts may be harmful to soil and plants. The concentration needs to be controlled and has been controlled within the standard range of ≤1%.

[0136] 3. Trace element analysis

[0137] Lithium (Li): 0.1 g / L. Lithium has limited effects in plants, but it has some influence on the growth regulation of certain crops.

[0138] Rubidium (Rb): 0.8 g / L. Rubidium has a certain promoting effect on plant growth and metabolism.

[0139] Cesium (Cs): 0.1 g / L. Cesium has a relatively small effect in plants, but may have an auxiliary effect on the growth of some crops.

[0140] Fluorine (F): 0.01 g / L. Fluorine is an essential micronutrient for plants and helps to enhance disease resistance.

[0141] Iron (Fe): Not listed directly, but trace amounts of iron may be present in organic matter.

[0142] Zinc (Zn): Not listed directly, but trace amounts of zinc may be present in organic matter.

[0143] Manganese (Mn): Not listed directly, but trace amounts of manganese may be present in organic matter.

[0144] Copper (Cu): Not listed directly, but trace amounts of copper may be present in organic matter.

[0145] Boron (B): Not listed directly, but trace amounts of boron may be present in organic matter.

[0146] 4. Organic matter analysis

[0147] Organic matter: 2.1 g / L. Organic matter helps improve the slow-release effect of fertilizer, enhances the efficiency of plant nutrient absorption, and improves soil structure.

[0148] The analysis of the test results of the filtrate after lithium precipitation in Table 2 and the requirements of national standards shows that the ratio of macroelements (N, P, K, S) and mesoelements (Ca, Mg, Si) in the remaining filtrate after lithium precipitation in this invention is reasonable and meets the needs of plant growth. The content of microelements is low, which conforms to the principle of microelement use in foliar fertilizers. The organic matter content is moderate, which helps to improve the absorption and utilization rate of fertilizer. Moreover, the levels of other heavy metals (such as mercury, arsenic, cadmium, lead, and chromium) are all lower than the implementation standard of GB / T 17419-2018 "Follicular Fertilizers Containing Organic Matter". This proves that the nutrient solution treated by the process in Example 4 can be used as a complete nutrient foliar fertilizer, realizing a closed loop of "recycling equals added value".

[0149] In summary, the method for high-efficiency lithium extraction from lepidolite using sulfonate-based low-temperature enhanced roasting of the present invention first pre-activates the lepidolite concentrate using an air jet mill. This process involves high-speed particle collision, shearing, and friction within the air jet mill, simultaneously disrupting the lepidolite crystal structure and activating its surface. This provides more favorable reaction conditions for subsequent efficient lithium extraction (such as roasting or leaching). Then, by using aminosulfonate and sulfuric acid synergistically for lithium extraction, the stability of the acid and its selectivity for lithium are effectively enhanced. Compared to the sulfuric acid method alone, this method significantly improves the lithium conversion rate from lepidolite while reducing the roasting temperature and saving energy. Furthermore, while the sulfuric acid method alone is highly adaptable to raw materials, it generates a large amount of waste residue. The addition of aminosulfonate effectively reduces the amount of residue and environmental pollution, which is of great significance for the sustainable development of the lithium industry and has significant application value in the field of ore-based lithium extraction technology.

[0150] The present invention discloses a method for efficient lithium extraction from lithium mica by low-temperature enhanced roasting of sulfonate compound. The remaining filtrate after lithium precipitation is rich in nitrogen and potassium elements. After synergistic treatment with chelating agents, adjuvants, wetting agents and pH adjusters, it can be used as a complete nutrient foliar fertilizer, effectively realizing a closed loop of "recycling equals added value". It has promotion and application value in the field of resource recycling technology.

[0151] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite, characterized in that, Includes the following steps: S1. Pre-activation treatment of lepidolite concentrate to obtain activated lepidolite concentrate powder; S2. Mix lepidolite concentrate powder with composite roasting agent, and then acid-roast at a temperature below 300 ℃ to obtain roasted product; S3. Add water to the calcined product and leach to obtain a lithium-containing leachate; The composite calcining agent is a mixture of acid and sulfonate; The pre-activation treatment involves placing lepidolite concentrate in an air jet mill, controlling the airflow velocity at 300-500 m / s, the nozzle pressure at 0.8-1.2 MPa, the classifier wheel speed at 3000-5000 rpm, and the feeding speed at 50-200 kg / h, in order to achieve pre-activation of the lepidolite concentrate. The sulfonate is selected from one or both of ammonium aminosulfonate and sodium aminosulfonate; The acid is selected from concentrated sulfuric acid.

2. The method for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite according to claim 1, characterized in that, The chemical composition and mass percentage of the lepidolite concentrate are as follows: Li₂O 2.3%, SiO₂ 45.7%, Al₂O₃ 21.1%, K₂O 8.1%, Na₂O 4.9%, F 4.6%, CaO 3.1%, Fe₂O₃ 1.3%, Rb₂O 0.4%, Cs₂O 0.1%, with the remainder being other impurities.

3. The method for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite according to claim 1, characterized in that, The sulfonate is selected from ammonium aminosulfonate and sodium aminosulfonate; And / or, the sulfonate is added in the form of an aqueous sulfonate solution, wherein the concentration of the sulfonate in the aqueous sulfonate solution is 150~200 g / L; The mass ratio of the lithium mica concentrate powder, concentrated sulfuric acid, ammonium aminosulfonate, and sodium aminosulfonate is 1:0.6~0.8:0.2~0.5:0.3~0.

6.

4. The method for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite according to claim 1, characterized in that, The acidification and roasting temperature is 130~300 ℃; And / or, the acidification and roasting time is 60-90 min.

5. The method for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite according to claim 1, characterized in that, The water immersion temperature is 90~99℃; And / or, the soaking time in water is 60-90 min; And / or, the mass ratio of the calcined product to water is 1:3~5.

6. The method for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite according to claim 1, characterized in that, Also includes: S4. The lithium-containing leachate is passed through a precipitant to remove aluminum / fluorine impurities, resulting in a purified lithium-containing leachate. S5. Evaporate and concentrate the lithium-containing leachate after impurity removal, then add a lithium precipitation agent to carry out a lithium precipitation reaction at room temperature and pressure, filter, and obtain lithium precipitate product and residual filtrate after lithium precipitation.

7. The method for efficient lithium extraction from sulfonate compound low-temperature enhanced roasting of lepidolite according to claim 6, characterized in that, The volume of the solution after evaporation and concentration is 1 / 4 of the volume of the lithium-containing leachate after impurity removal; And / or, the precipitant is selected from at least one of calcium hydroxide, magnesium hydroxide, barium hydroxide, and manganese hydroxide; And / or, the method of removing aluminum / fluorine impurities by using a precipitant is as follows: add a precipitant to the lithium-containing leaching solution to adjust the pH value of the lithium-containing leaching solution to above 12, thereby removing aluminum / fluorine impurities; And / or, the lithium precipitation agent is selected from sodium dihydrogen phosphate, and the amount of sodium dihydrogen phosphate used is more than 4 times the mass of Li2O in the lithium-containing leachate after impurity removal.

8. An application of the residual filtrate obtained after lithium precipitation by the method according to any one of claims 1 to 7, characterized in that, The remaining filtrate after lithium precipitation is treated and then applied as a foliar fertilizer for plants. The treatment method includes: adding a chelating agent to the remaining filtrate after lithium precipitation, and carrying out a chelation reaction at a temperature of 40~45 ℃ to obtain a chelated solution; The chelating solution, auxiliary agent, and wetting agent are mixed and compounded, then filtered to obtain the compound filtrate. The compound filtrate was diluted and the pH was adjusted to 5.5-6.5 to obtain a nutrient solution that can be used as a complete foliar fertilizer.

9. The application according to claim 8, characterized in that, The composition and content of the remaining filtrate after lithium precipitation include: 0.1 g / L Li, 0.8 g / L Rb, 0.1 g / L Cs, 3.0 g / L Na, 2.8 g / L K, 0.01 g / L Al, 1.9 g / L Si, 0.5 g / L Ca, 0.3 g / L Mg, 0.01 g / L F, 5.0 g / L N, 2.0 g / L P, 2.1 g / L S, and 2.1 g / L organic matter. Other heavy metals are all below the implementation standard of GB / T 17419-2018 "Follicular Fertilizers Containing Organic Matter". And / or, the chelating agent is selected from one or both of ethylenediaminetetraacetic acid and citric acid; And / or, the adjuvant is selected from one or two of agricultural organosilicon and sodium dodecyl sulfate; and / or, the wetting agent is selected from at least one of triethanolamine, glycerin and urea.

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