Method for efficiently extracting lithium from sulfonate compounded low-temperature reinforced roasted lepidolite and application

Abstract

The invention relates to a method for efficiently extracting lithium from sulfonate compounded low-temperature reinforced roasted lepidolite and application of the method. The invention relates to a method for efficiently extracting lithium from sulfonate compounded low-temperature reinforced roasted lepidolite, which comprises the following steps of: pre-activating lepidolite concentrate to obtain activated lepidolite concentrate powder; mixing the lepidolite concentrate powder with a composite roasting agent, and then acidizing and roasting at the temperature of less than 300 DEG C to obtain a roasted product; adding water into the roasted product for leaching to obtain a lithium-containing leaching solution; the composite roasting agent is a mixture of acid and sulfonate. The invention also provides an application of the residual filtrate after lithium precipitation obtained by the method, and the residual filtrate after lithium precipitation is treated and then applied as a plant leaf fertilizer. The method solves the problem of high operation temperature in the existing method for extracting lithium from lepidolite, and also solves the problems of easy environmental pollution and high cost in the existing method for extracting lithium from lepidolite.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium extraction from ores, and in particular to a method and application of efficiently extracting lithium from lepidolite by compounding sulfonate with low-temperature enhanced roasting. Background Art

[0002] Lepidolite, a valuable lithium resource, is a key raw material for producing battery-grade lithium carbonate. With the rapid development of new energy technologies, the demand for battery-grade lithium carbonate is growing. Consequently, efficient lithium extraction technologies from lepidolite have become a hot topic of research. Currently, lepidolite lithium extraction processes primarily include autoclaving, chloride roasting, sulfate roasting, and lithium carbonate roasting (limestone method). Yichun, Jiangxi Province, leveraging its abundant lepidolite resources, has, through years of technological accumulation and development, established a lepidolite lithium extraction process primarily based on sulfate roasting.

[0003] Despite the diverse development of lithium extraction technologies from lepidolite, each method has limitations. For example, while the chloride salt roasting method can process lepidolite ore of varying grades, it consumes a large amount of auxiliary materials, operates at high temperatures, and generates significant environmental pollution during production. While the autoclave method achieves highly efficient lithium extraction, it requires extremely high equipment requirements, incurs high initial investment costs, and also generates environmental pollution during production. While the calcium carbonate roasting method (limestone method) offers a relatively simple process, it consumes a large amount of auxiliary materials, operates at high temperatures, and is prone to caking during the roasting process, resulting in increased costs. The sulfate roasting method, currently the mainstream process for lithium extraction from lepidolite, while offering high lithium extraction efficiency, also faces challenges such as high operating temperatures, high auxiliary material consumption, and difficulty in achieving profitability. Summary of the Invention

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

[0005] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting, comprising the following steps: S1, pre-activating the lepidolite concentrate to obtain activated lepidolite concentrate powder; S2, mixing the lepidolite concentrate powder with a composite roasting agent, and then acidifying and roasting at a temperature less than 300° C. to obtain a roasted product; S3, adding water to the roasted product for leaching to obtain a lithium-containing leachate; The composite roasting agent is a mixture of acid and sulfonate.

[0006] According to the above-mentioned technical means, by using aminosulfonates and sulfuric acid to extract lithium in a coordinated manner, the acid stability and selectivity for lithium are effectively enhanced. Compared with the sulfuric acid method alone, the conversion rate of lithium in lepidolite can be effectively increased, while the roasting temperature is effectively reduced, saving energy consumption. This solves the problem of high operating temperature in existing lepidolite lithium extraction methods. Moreover, the leached solution is rich in nitrogen and potassium and can be used as foliar fertilizer, achieving a closed loop of "recycling and value-added". Although the sulfuric acid method alone has strong adaptability to raw materials, it produces a large amount of waste residue. The addition of aminosulfonates can reduce the amount of waste residue and reduce environmental pollution. This solves the environmental pollution and high cost problems 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 promotional and application value in the field of ore lithium extraction technology.

[0007] Among them, the principle analysis of the synergistic effect of aminosulfonate and sulfuric acid: 1) Synergistically enhance the acidic environment: sulfuric acid provides SO4 2- Ions exchange with lithium ions to form soluble lithium sulfate. + and H provided by sulfuric acid + The combined effect promotes 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.

[0008] 2) Lower the calcination temperature: Sulfuric acid (H2SO4) is a strong acid that can destroy the lattice structure of metal compounds and provide a large amount of H + , replacing the metal ions in the lepidolite to form a stable complex. The hydrolysis products of aminosulfonates (such as NH4SO4 - ) will also combine with metal ions to form soluble salts or complexes. Sulfuric acid and sulfamates work synergistically to reduce the activity of metal ions, further increasing the reaction rate. Therefore, the temperature required for acid roasting can be lowered, reducing energy consumption and improving reaction efficiency.

[0009] 3) Optimizing the roasting environment and reducing side reactions: The addition of sulfamate can reduce the decomposition of sulfuric acid at high temperatures and reduce the release of SO₃ gas, thereby improving the safety and stability of the roasting process. Compared to sulfuric acid, sulfamate is inherently more stable and less toxic. The synergistic effect of sulfuric acid and sulfamate can reduce the formation of byproducts such as HF, thereby improving lithium purity and recovery rate.

[0010] In summary, the synergistic effect of sulfamate and sulfuric acid is primarily achieved by enhancing the acidic environment, lowering the calcination temperature, optimizing the calcination environment, and reducing side reactions. These mechanisms work together to significantly increase lithium conversion, enhance the stability of the acid system, and reduce environmental pollution.

[0011] Preferably, the preactivation treatment is to place the lepidolite concentrate in a jet mill, control the air flow velocity to 300~500m / s, the nozzle pressure to 0.8~1.2MPa, the classifying wheel speed to 3000~5000rpm, and the feeding rate to 50~200kg / h to achieve preactivation of the lepidolite concentrate.

[0012] By using a jet mill to pre-activate the lepidolite concentrate, the high-speed airflow (300-500 m / s) in the jet mill drives the particles to collide, shear and rub at high speed to achieve crushing, while causing the following changes in the lepidolite crystal structure: 1) Lattice distortion and defect increase: The strong mechanical force causes the layered structure of the lepidolite to break, and a large number of defects, dislocations and amorphous areas are generated in the lattice, thereby exposing more active sites and improving the chemical reaction activity; 2) Increased specific surface area: The particles are ultra-fine, the particle size is significantly reduced, and the specific surface area is increased, which improves the contact efficiency in subsequent reactions (such as acid leaching) and disorderes the surface atomic arrangement, thereby further increasing the 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 conducive to the dissolution of lithium. 4) Phase structure transformation: Under the impact and shear of airflow, some lepidolite crystal structures can transform from a stable state to a metastable state, and even become locally amorphous, effectively promoting phase transformation reactions during subsequent roasting or leaching. In summary, pre-activation in airflow mills not only achieves physical pulverization of lepidolite concentrates, but also provides more favorable reaction conditions for subsequent efficient lithium extraction (such as roasting transformation or leaching) through crystal structure destruction and surface activation induced by high-energy mechanical forces.

[0013] Jet mills utilize high-speed airflow to pulverize material particles through interparticle collisions and frictional shearing. This process is accompanied by the following activation effects: particle miniaturization significantly increases specific surface area and disorderes the atomic arrangement on the surface, thereby increasing active sites. Rapid impact disrupts the periodicity of the mineral crystal structure, creating lattice defects (such as dislocations and vacancies), thereby enhancing chemical reactivity. When compressed air is released through the Laval nozzle, the temperature within the pulverization chamber typically does not rise significantly due to the adiabatic expansion effect, generally remaining below 30°C.

[0014] Preferably, the chemical composition and mass percentage of the lepidolite concentrate are: 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%, Cs2O0.1%, and the rest are other impurities.

[0015] Preferably, the sulfonate is selected from one or both of ammonium sulfamate and sodium sulfamate; The acid is selected from concentrated sulfuric acid.

[0016] Preferably, when the sulfonate is selected from ammonium sulfamate, the mass ratio of the lepidolite concentrate powder, concentrated sulfuric acid and ammonium sulfamate is 1:0.6~0.8:0.2~0.5.

[0017] Preferably, when the sulfonate is selected from sodium sulfamate, the mass ratio of the lepidolite concentrate powder, concentrated sulfuric acid and sodium sulfamate is 1:0.6~0.8:0.3~0.6.

[0018] Preferably, the sulfonate is selected from ammonium sulfamate and sodium sulfamate; The concentration of sulfonate solution is 150~200 g / L; The mass ratio of the lepidolite concentrate powder, concentrated sulfuric acid, ammonium sulfamate and sodium sulfamate is 1:0.6-0.8:0.2-0.5:0.3-0.6.

[0019] Preferably, the temperature of the acidification calcination is 130-300°C.

[0020] Preferably, the temperature of the acidification roasting is 60-90 min.

[0021] Preferably, the temperature of the water leaching is 90-99°C.

[0022] Preferably, the water leaching time is 60 to 90 minutes.

[0023] Preferably, the mass ratio of the roasted product to water is 1:3-5.

[0024] Preferably, it also includes: S4, removing aluminum / fluorine impurities from the lithium-containing leachate through a precipitant to obtain a lithium-containing leachate after impurities removal; S5. The lithium-containing leachate after impurity removal is evaporated and concentrated, and then a lithium precipitation agent is added to carry out lithium precipitation reaction at room temperature and pressure, and filtered to obtain a lithium precipitate product and a residual filtrate after lithium precipitation.

[0025] Preferably, the volume of the solution after evaporation and concentration is 1 / 4 of the volume of the lithium-containing leachate after impurities removal.

[0026] Preferably, the precipitant is selected from at least one of calcium hydroxide, magnesium hydroxide, barium hydroxide and manganese hydroxide.

[0027] Preferably, the precipitating agent is selected from calcium hydroxide.

[0028] Preferably, the method of removing aluminum / fluorine impurities by a precipitant is: by adding a precipitant to the lithium-containing leachate to adjust the pH value of the lithium-containing leachate to above 12, thereby removing aluminum / fluorine impurities.

[0029] Preferably, the lithium precipitating agent is selected from sodium dihydrogen phosphate, and the amount of the sodium dihydrogen phosphate used is more than 4 times the mass of Li2O in the lithium-containing leachate after impurities are removed.

[0030] The present invention also provides an application of the residual filtrate after lithium precipitation obtained by the method of the present invention, wherein the residual filtrate after lithium precipitation is treated and applied as a foliar fertilizer for plants.

[0031] Preferably, the treatment method comprises: treating the remaining filtrate after lithium precipitation and applying it as plant foliar fertilizer.

[0032] Preferably, the treatment method specifically comprises: adding a chelating agent to the remaining filtrate after lithium precipitation, performing a chelating reaction at a temperature of 40-45° C. to obtain a chelating solution; The chelating solution, the auxiliary agent and the wetting agent are mixed and compounded, and filtered to obtain a compound filtrate; The compound filtrate is diluted and the pH value is adjusted to 5.5-6.5 to obtain a nutrient solution as a complete nutrient foliar fertilizer.

[0033] Preferably, the composition of the residual 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, and other heavy metals (such as mercury, arsenic, cadmium, lead, and chromium) are all lower than the implementation standard of GB / T 17419-2018 "Foliar Fertilizers Containing Organic Matter".

[0034] Preferably, the chelating agent is selected from one or both of EDTA (ethylenediaminetetraacetic acid) and citric acid.

[0035] Preferably, the mass percentage of the chelating agent in the chelating solution is 0.1-0.3%.

[0036] Preferably, the adjuvant is selected from one or both of agricultural organosilicon and SDS (sodium dodecyl sulfate).

[0037] Preferably, the mass percentage of agricultural organosilicon in the composite filtrate is 0.02-0.06%.

[0038] Preferably, the mass percentage of agricultural organosilicon in the composite filtrate is 0.04%.

[0039] Preferably, the mass percentage of SDS in the composite filtrate is 0.02-0.06%.

[0040] Preferably, the wetting agent is selected from at least one of triethanolamine, glycerol and urea.

[0041] Preferably, the mass percentage of triethanolamine in the composite filtrate is 0.02-0.06%.

[0042] Preferably, the mass percentage of glycerol in the composite filtrate is 0.02-0.06%.

[0043] Preferably, the mass percentage of urea in the composite filtrate is 0.02-0.06%.

[0044] Preferably, the filtration is performed by pre-filtration through a 1-5 μm filter membrane and then fine filtration through a 0.45 μm filter membrane.

[0045] Preferably, the dilution multiple of the composite filtrate is determined according to the ion concentration in the composite filtrate, and the concentration of all single ions is required to be less than 0.5 g / L.

[0046] Preferably, humic acid is used to adjust the liquid after dilution of the composite filtrate to maintain the stability of the pH of the nutrient solution, thereby promoting nutrient absorption.

[0047] Preferably, the nutrient solution as a complete nutrient foliar fertilizer can be safely used as a complete nutrient foliar fertilizer for lithium-enriched crops, silicon-requiring crops, salt-alkali-tolerant crops and micro-potassium-loving crops, so as to achieve the dual goals of industrial waste liquid resource utilization and agricultural quality and efficiency improvement.

[0048] Among them, the lithium-enriched crop is sunflower, the silicon-requiring crop is rice, the salt-alkali-tolerant crop is seawater rice, and the micro-potassium-loving crop is potato.

[0049] Beneficial effects of the present invention: The method of the present invention for efficiently extracting lithium from lepidolite by combining sulfonates with low-temperature enhanced roasting of lepidolite is first performed by pre-activating the lepidolite concentrate using a jet mill, so that the lepidolite concentrate is subjected to high-speed particle collision, shearing, and friction in the jet mill, while the lepidolite crystal structure is destroyed and the surface is activated, providing more favorable reaction conditions for subsequent efficient lithium extraction (such as roasting transformation or leaching). Then, aminosulfonates are used in conjunction with sulfuric acid to extract lithium, effectively enhancing the stability of the acid and the selectivity for lithium. Compared with the sulfuric acid method alone, the conversion rate of lithium in the lepidolite is effectively increased, while the roasting temperature is reduced, saving energy consumption. At the same time, although the sulfuric acid method alone has strong adaptability to raw materials, it produces a large amount of waste residue. The addition of aminosulfonates effectively reduces the amount of slag and reduces environmental pollution, which is of great significance to the sustainable development of the lithium industry and has promotion and application value in the field of lithium extraction technology from ore.

[0050] The method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting is characterized in that the remaining filtrate after lithium precipitation is rich in nitrogen and potassium elements. Therefore, the remaining filtrate after lithium precipitation can be used as a full-nutrient foliar fertilizer after being synergistically treated with a chelating agent, an adjuvant, a wetting agent, and a pH regulator, effectively realizing a closed loop of "recycling and value-added" and having promotion and application value in the field of resource recycling and utilization technology. DETAILED DESCRIPTION

[0051] The following will describe the embodiments of the present invention with reference to preferred embodiments. Those skilled in the art will readily appreciate the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are intended only to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0052] If no specific techniques or conditions are specified in the specific examples, the techniques or conditions described in the literature in this field or the product instructions were used. If no manufacturer is specified for the reagents or instruments used, they are all commercially available conventional products.

[0053] In the following examples, the chemical composition and mass percentage of the lepidolite concentrate used are: Li2O 2.3%, SiO245.7%, Al2O3 21.1%, K2O 8.1%, Na2O 4.9%, F 4.6%, CaO 3.1%, Fe2O3 1.3%, Rb2O 0.4%, Cs2O 0.1%, and the remainder is other impurities.

[0054] Example 1 A method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting, comprising the following steps: S1, 1000 g of lepidolite concentrate was added to a jet mill, and the air velocity, nozzle pressure, and classifier wheel speed were controlled to be 350 m / s, 0.8 MPa, 3000 rpm, and 50 kg / h, respectively, to obtain activated lepidolite concentrate powder; S2, the lepidolite concentrate powder obtained in S1 is mixed with a composite roasting agent, and then placed in a roasting furnace at a temperature of 150 ° C for acidification and roasting for 60 min to obtain a roasted product; wherein, the composite roasting agent comprises concentrated sulfuric acid and sodium sulfamate with a concentration of 98%; the mass ratio of the lepidolite concentrate powder, the concentrated sulfuric acid with a concentration of 98% and the sodium sulfamate is 1:0.6:0.5; the addition mode of sodium sulfamate is that sodium sulfamate is dissolved in water to form a sodium sulfamate solution with a concentration of 150 g / L, and then added as a solution; S3, mixing the roasted product obtained in S2 with pure water in a mass ratio of 1:5, and then stirring and leaching in a water bath at a temperature of 90° C. for 60 min, and filtering to obtain a lithium-containing leachate and a leach residue; S4, adding Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities by the precipitant, and obtain a lithium-containing leachate after impurity removal; S5. The lithium-containing leachate after impurity removal was evaporated and concentrated 4 times, and then 92 g of sodium dihydrogen phosphate lithium precipitation agent was added to carry out lithium precipitation reaction, and the lithium precipitate product and the remaining filtrate after lithium precipitation were obtained by filtration.

[0055] Example 2 A method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting, comprising the following steps: S1, 1000 g of lepidolite concentrate was added to a jet mill, and the air velocity was controlled to be 300 m / s, the nozzle pressure was 0.9 MPa, the classifying wheel speed was 3200 rpm, and the feeding rate was 60 kg / h to obtain activated lepidolite concentrate powder; S2, the lepidolite concentrate powder obtained in S1 is mixed with a composite roasting agent, and then placed in a roasting furnace at a temperature of 150 ° C for acidification and roasting for 60 min to obtain a roasted product; wherein the composite roasting agent comprises concentrated sulfuric acid and ammonium sulfamate with a concentration of 98%; the mass ratio of the lepidolite concentrate powder, the concentrated sulfuric acid with a concentration of 98% and the ammonium sulfamate is 1:0.6:0.5; the addition mode of ammonium sulfamate is that ammonium sulfamate is dissolved in water to form an ammonium sulfamate solution with a concentration of 200 g / L, and then added in the form of a solution; S3, mixing the roasted product obtained in S2 with pure water in a mass ratio of 1:5, and then stirring and leaching in a water bath at a temperature of 95° C. for 60 min, and filtering to obtain a lithium-containing leachate and a leach residue; S4, adding Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities by the precipitant, and obtain a lithium-containing leachate after impurity removal; S5. The lithium-containing leachate after impurity removal was evaporated and concentrated 4 times, and then 95 g of sodium dihydrogen phosphate lithium precipitation agent was added to carry out lithium precipitation reaction, and the lithium precipitate product and the remaining filtrate after lithium precipitation were obtained by filtration.

[0056] Example 3 A method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting, comprising the following steps: S1, 1000 g of lepidolite concentrate was added to a jet mill, and the air velocity was controlled to be 300 m / s, the nozzle pressure was 0.9 MPa, the classifying wheel speed was 3500 rpm, and the feeding rate was 50 kg / h to obtain activated lepidolite concentrate powder; S2, the lepidolite concentrate powder obtained in S1 is mixed with a composite roasting agent, and then placed in a roasting furnace at a temperature of 180 ° C for acidification and roasting for 90 min to obtain a roasted product; wherein, the composite roasting agent comprises concentrated sulfuric acid, ammonium sulfamate and sodium sulfamate at a concentration of 98%; the mass ratio of the lepidolite concentrate powder, the concentrated sulfuric acid, ammonium sulfamate and sodium sulfamate at a concentration of 98% is 1:0.6:0.2:0.3; the addition mode of ammonium sulfamate and sodium sulfamate is that ammonium sulfamate and sodium sulfamate are dissolved in water to form a sulfamate solution with a total concentration of 200 g / L of sulfamate, which is then added as a solution; S3, mixing the roasted product obtained in S2 with pure water in a mass ratio of 1:5, and then stirring and leaching for 90 min in a water bath at a temperature of 95° C., and filtering to obtain a lithium-containing leachate and a leach residue; S4, adding Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities by the precipitant, and obtain a lithium-containing leachate after impurity removal; S5. The lithium-containing leachate after impurity removal was evaporated and concentrated 4 times, and then 103 g of sodium dihydrogen phosphate lithium precipitation agent was added to carry out lithium precipitation reaction, and the lithium precipitate product and the remaining filtrate after lithium precipitation were obtained by filtration.

[0057] Example 4 A method for treating the residual filtrate obtained by filtering and precipitating lithium in step S5 of Example 1 and applying it as a plant foliar fertilizer comprises the following steps: S1. Adding chelating agent EDTA to the remaining filtrate after lithium precipitation, carrying out a chelation reaction at a temperature of 40-45°C to obtain a chelating solution; the mass percentage of EDTA in the chelating solution is 0.2%; S2. The chelating solution, the adjuvant agricultural organosilicon, and the wetting agent glycerin in S1 are mixed and compounded, and then pre-filtered through a 1-5 μm filter membrane, and then fine-filtered through a 0.45 μm filter membrane to obtain a compounded solution; the mass percentage of agricultural organosilicon and glycerin in the compounded solution is 0.04% each; S3. The compound solution obtained in S2 is determined according to the ion concentration in the compound filtrate, requiring that the concentration of all single ions is less than 0.5 g / L, and then the pH value is adjusted to 6.0 using humic acid to maintain pH stability and promote nutrient absorption, thereby obtaining a nutrient solution as a complete foliar fertilizer.

[0058] Comparative Example 1 A method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting, comprising the following steps: S1, 1000 g of lepidolite concentrate powder is mixed with a composite roasting agent, then placed in a roasting furnace at a temperature of 180 ° C for acidification and roasting for 90 min to obtain a roasted product; wherein, the composite roasting agent comprises 98% concentrated sulfuric acid, ammonium sulfamate and sodium sulfamate; the mass ratio of lepidolite concentrate powder, concentration being 98% concentrated sulfuric acid, sodium sulfamate and ammonium sulfamate is 1:0.6:0.2:0.3; the addition mode of sodium sulfamate and ammonium sulfamate is that sodium sulfamate and ammonium sulfamate are dissolved in water to form a sulfamate solution with a total concentration of 200 g / L, which is then added as a solution; S3, mixing the roasted product obtained in S2 with pure water in a mass ratio of 1:5, and then stirring and leaching for 90 min in a water bath at a temperature of 95° C., and filtering to obtain a lithium-containing leachate and a leach residue; S4, adding Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities by the precipitant, and obtain a lithium-containing leachate after impurity removal; S5. The lithium-containing leachate after impurity removal was evaporated and concentrated 4 times, and then 92 g of sodium dihydrogen phosphate lithium precipitation agent was added to carry out lithium precipitation reaction, and the lithium precipitate product and filtrate were obtained by filtration.

[0059] Comparative Example 2 A method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting, comprising the following steps: S1, 1000 g of lepidolite concentrate was added to a jet mill, and the air velocity was controlled to be 300 m / s, the nozzle pressure was 0.9 MPa, the classifying wheel speed was 3500 rpm, and the feeding rate was 50 kg / h to obtain activated lepidolite concentrate powder; S2, the lepidolite concentrate powder obtained in S1 is mixed with 98% concentrated sulfuric acid, and then placed in a roaster at a temperature of 180°C for acidification and roasting for 90 min to obtain a roasted product; wherein the mass ratio of the lepidolite concentrate powder to the 98% concentrated sulfuric acid is 1:0.8; S3, mixing the roasted product obtained in S2 with pure water in a mass ratio of 1:4, then stirring and leaching in a water bath at a temperature of 95° C. for 90 min, and filtering to obtain a lithium-containing leachate and a leach residue; S4, adding Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities by the precipitant, and obtain a lithium-containing leachate after impurity removal; S5. The lithium-containing leachate after impurity removal was evaporated and concentrated 4 times, and then 95 g of sodium dihydrogen phosphate lithium precipitation agent was added to carry out lithium precipitation reaction, and the lithium precipitate product and filtrate were obtained by filtration.

[0060] Comparative Example 3 The traditional lithium extraction process of lepidolite by high-temperature sulfuric acid roasting includes the following steps: S1, 1000 g of lepidolite concentrate powder was mixed with 98% concentrated sulfuric acid, and then placed in a roaster at a temperature of 900 ° C for acidification and roasting for 150 min to obtain a roasted product; wherein the mass ratio of the lepidolite concentrate powder to the concentrated sulfuric acid with a concentration of 98% was 1:0.8; S3, mixing the roasted product obtained in S2 with pure water in a mass ratio of 1:4, then stirring and leaching in a water bath at a temperature of 95° C. for 90 min, and filtering to obtain a lithium-containing leachate and a leach residue; S4, adding Ca(OH)2 to the lithium-containing leachate to adjust the pH value to above 12, so as to remove aluminum / fluorine impurities by the precipitant, and obtain a lithium-containing leachate after impurity removal; S5. The lithium-containing leachate after impurity removal was evaporated and concentrated 4 times, and then 103 g of sodium dihydrogen phosphate lithium precipitation agent was added to carry out lithium precipitation reaction, and the lithium precipitate product and filtrate were obtained by filtration.

[0061] Detection and Analysis 1) Determination of Li2O content in leached residue, pH value of lithium-containing leachate, leached residue yield, and Li2O leaching rate in lepidolite concentrate The calculation formula for the Li2O leaching rate in lepidolite concentrate is: lithium leaching rate = [leachate volume (L) * lithium oxide concentration in leachate (g / L)] / [lithium oxide content in lepidolite concentrate (%) * lepidolite concentrate mass (g)] * 100% Yield of leaching residue (%) = [100% × dry weight of leaching residue (g)] / dry weight of lepidolite concentrate powder (g) The results are shown in Table 1.

[0062] Table 1 shows the results of the determination of lithium-containing leachate and leach residue From the analysis in Table 1, it can be seen that by pre-activating the lepidolite concentrate by jet milling, then using 98% concentrated sulfuric acid and one or two mixtures of ammonium sulfamate and sodium sulfamate as a composite roasting agent, and then carrying out the leaching reaction, the Li2O leaching rate can be made above 90%. By comparing Example 3 and Comparative Example 1, it can be seen that when the lepidolite concentrate is pre-activated by a jet mill, the leaching rate of Li2O in the leachate is increased by 11.92% compared with that of the unactivated one; the yield of lithium slag is reduced by 7.13%; by comparing Example 3 and Comparative Example 2, it can be seen that when 98% concentrated sulfuric acid and sulfonate composite roasting agent are used, the leaching rate of Li2O in the leachate is increased by 13.97% compared with the leaching rate of 98% concentrated sulfuric acid alone as a roasting agent, and the yield of lithium slag is reduced by 20.54%; by comparing Example 3 and Comparative Example 3, it can be seen that when the lepidolite concentrate is pre-activated by a jet mill and 98% concentrated sulfuric acid and sulfonate composite roasting agent are used, the leaching rate of Li2O in the leachate is increased by 22.84% compared with the leaching rate of the traditional sulfuric acid 900°C high temperature roasting process, and the yield of lithium slag is reduced by 22.25%. This demonstrates that the novel process of the present invention, which adopts a sulfonate-compounded low-temperature roasting method, significantly improves the leaching rate of Li2O, reduces the amount of slag, and can achieve the conversion of lithium in lepidolite at a lower temperature, thereby saving energy consumption and reducing production costs.

[0063] 2) Determination of composition and content of the remaining filtrate after lithium precipitation The composition and content of the residual filtrate after lithium precipitation obtained in S5 of Example 1 were determined using an inductively coupled plasma spectrometer (ICP-OES), an atomic absorption spectrometer (AAS), an ion chromatograph (IC), and an elemental analyzer (CHNS mode). The results are shown in Table 2.

[0064] Table 2 Residual filtrate composition and content determination results after lithium precipitation According to the national standard GB / T 17419-2018, it stipulates the requirements, test methods, inspection rules, labeling, packaging, transportation and storage of foliar fertilizers containing organic matter. This standard applies to water-soluble fertilizers containing organic matter, including both liquid and solid forms. Compared with the national standard GB / T 17419-2018: 1. Analysis of a large number of elements Nitrogen (N): 5.0 g / L, which is a medium concentration and suitable for supplementing the nitrogen required for crop growth and promoting the growth of leaves and stems.

[0065] Phosphorus (P): 2.0 g / L. Phosphorus is an important element for plant growth, contributing to root development and flower and fruit formation.

[0066] Potassium (K): 2.8 g / L. Potassium can enhance the stress resistance of crops and the quality of fruits.

[0067] Sulfur (S): 2.1 g / L. Sulfur is an essential secondary element for plants and helps improve the taste and aroma of crops.

[0068] 2. Medium element analysis Calcium (Ca): 0.5 g / L. Calcium helps form cell walls and enhances the disease resistance of crops.

[0069] Magnesium (Mg): 0.3 g / L. Magnesium is a key element for chlorophyll synthesis and promotes photosynthesis.

[0070] Silicon (Si): 1.9 g / L. Silicon can enhance the lodging resistance and disease resistance of crops.

[0071] Aluminum (Al): 0.01 g / L. Aluminum has a regulatory effect on some crops, but excessive amounts may be harmful to the soil and plants. The concentration needs to be controlled and has been controlled within the standard range of ≤1%.

[0072] 3. Trace element analysis Lithium (Li): 0.1 g / L. Lithium has limited effects on plants, but it has a certain impact on the growth regulation of certain crops.

[0073] Rubidium (Rb): 0.8 g / L. Rubidium has a certain promoting effect on plant growth and metabolism.

[0074] Cesium (Cs): 0.1 g / L. Cesium has little effect on plants, but may have an auxiliary effect on the growth of certain crops.

[0075] Fluorine (F): 0.01 g / L. Fluorine is an essential trace element for plants and helps enhance disease resistance.

[0076] Iron (Fe): Not directly listed, but trace amounts of iron may be present in organic matter.

[0077] Zinc (Zn): Not directly listed, but trace amounts may be present in organic matter.

[0078] Manganese (Mn): Not directly listed, but trace amounts may be present in organic matter.

[0079] Copper (Cu): Not directly listed, but trace amounts of copper may be present in organic matter.

[0080] Boron (B): Not directly listed, but trace amounts of boron may be present in organic matter.

[0081] 4. Organic matter analysis Organic matter: 2.1 g / L. Organic matter helps improve the slow-release effect of fertilizers, enhances the efficiency of plant nutrient absorption, and improves soil structure.

[0082] A comparative analysis of the filtrate test results after lithium precipitation (Table 2) and the requirements of national standards demonstrates that the balance of major elements (N, P, K, S) and minor elements (Ca, Mg, Si) in the residual filtrate after lithium precipitation is reasonable, meeting plant growth requirements. The trace element content is low, meeting the principles for trace element use in foliar fertilizers. The moderate organic matter content helps improve fertilizer absorption and utilization. Furthermore, other heavy metals (such as mercury, arsenic, cadmium, lead, and chromium) are all below the implementation standards of GB / T 17419-2018, "Foliar Fertilizers Containing Organic Matter." This demonstrates that the nutrient solution treated with the process described in Example 4 can be used as a complete foliar fertilizer, achieving a closed-loop "recycling and value-added" strategy.

[0083] In summary, the method of the present invention for efficiently extracting lithium from lepidolite by combining sulfonates with low-temperature enhanced roasting of lepidolite is to pre-activate the lepidolite concentrate by first using a jet mill, so that the lepidolite concentrate is subjected to high-speed particle collision, shearing and friction in the jet mill, while the crystal structure of the lepidolite is destroyed and the surface is activated, providing more favorable reaction conditions for the subsequent efficient extraction of lithium (such as roasting transformation or leaching). Then, by using aminosulfonates and sulfuric acid to synergistically extract lithium, the stability of the acid and the selectivity for lithium are effectively enhanced. Compared with the sulfuric acid method alone, the conversion rate of lithium in the lepidolite is effectively increased, while the roasting temperature is reduced and energy consumption is saved. At the same time, although the sulfuric acid method alone has strong adaptability to raw materials, it will produce a large amount of waste residue. The addition of aminosulfonates effectively reduces the amount of slag and reduces environmental pollution, which is of great significance to the sustainable development of the lithium industry and has promotion and application value in the field of lithium extraction technology from ore.

[0084] The method for efficiently extracting lithium from lepidolite by combining sulfonate with low-temperature enhanced roasting is characterized in that the remaining filtrate after lithium precipitation is rich in nitrogen and potassium elements and can be used as a full-nutrient foliar fertilizer after being synergistically treated with a chelating agent, an adjuvant, a wetting agent, and a pH regulator. This effectively realizes a closed loop of "recycling and value-added" and has promotional and application value in the field of resource recycling and utilization technology.

[0085] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or modification made by those skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A method for efficiently extracting lithium from lepidolite by low-temperature intensive roasting of sulfonate-compounded lepidolite, characterized in that: The following steps are involved: S1, pre-activating the lepidolite concentrate to obtain activated lepidolite concentrate powder; S2, mixing the lepidolite concentrate powder with a composite roasting agent, and then acidifying and roasting at a temperature less than 300° C. to obtain a roasted product; S3, adding water to the roasted product for leaching to obtain a lithium-containing leachate; The composite roasting agent is a mixture of acid and sulfonate.

2. The method for efficiently extracting lithium from lepidolite by sulfonate-compounded low-temperature enhanced roasting according to claim 1, characterized in that: The pre-activation treatment is to place the lepidolite concentrate in an air flow mill, control the air flow velocity to be 300-500 m / s, the nozzle pressure to be 0.8-1.2 MPa, the classifying wheel speed to be 3000-5000 rpm, and the feeding rate to be 50-200 kg / h to achieve pre-activation of the lepidolite concentrate; And / or, the chemical composition and mass percentage of the lepidolite concentrate are: 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%, and the remainder is other impurities.

3. The method for efficiently extracting lithium from lepidolite by sulfonate-compounded low-temperature enhanced roasting according to claim 1, characterized in that: The sulfonate is selected from one or both of ammonium sulfamate and sodium sulfamate; The acid is selected from concentrated sulfuric acid.

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

6.

5. The method for efficiently extracting lithium from lepidolite by sulfonate-compounded low-temperature enhanced roasting according to claim 1, characterized in that: The temperature of the acidification roasting is 130-300°C; And / or, the temperature of the acidification and roasting is 60-90 min.

6. The method for efficiently extracting lithium from lepidolite by sulfonate-compounded low-temperature enhanced roasting according to claim 1, characterized in that: The temperature of the water leaching is 90-99°C; And / or, the time for leaching with water is 60 to 90 minutes; And / or, the mass ratio of the roasted product to water is 1:3-5.

7. The method for efficiently extracting lithium from lepidolite by sulfonate-compounded low-temperature enhanced roasting according to claim 1, characterized in that: Also includes: S4, removing aluminum / fluorine impurities from the lithium-containing leachate through a precipitant to obtain a lithium-containing leachate after impurities removal; S5. The lithium-containing leachate after impurity removal is evaporated and concentrated, and then a lithium precipitation agent is added to carry out lithium precipitation reaction at room temperature and pressure, and filtered to obtain a lithium precipitate product and a residual filtrate after lithium precipitation.

8. The method for efficiently extracting lithium from lepidolite by sulfonate-compounded low-temperature enhanced roasting according to claim 7, characterized in that: The volume of the solution after evaporation and concentration is 1 / 4 of the volume of the lithium-containing leachate after impurities removal; and / or, the precipitant is selected from at least one of calcium hydroxide, magnesium hydroxide, barium hydroxide and manganese hydroxide; and / or, removing aluminum / fluorine impurities by a precipitant by adding a precipitant to the lithium-containing leachate to adjust the pH value of the lithium-containing leachate to above 12 to remove aluminum / fluorine impurities; And / or, the lithium precipitating agent is selected from sodium dihydrogen phosphate, and the amount of the sodium dihydrogen phosphate is more than 4 times the mass of Li2O in the lithium-containing leachate after impurities are removed.

9. A use of the residual filtrate obtained after lithium precipitation by the method according to any one of claims 1 to 8, characterized in that: The remaining filtrate after lithium precipitation is treated and applied as plant foliar fertilizer; The treatment method comprises: adding a chelating agent to the remaining filtrate after lithium precipitation, performing a chelating reaction at a temperature of 40-45° C. to obtain a chelating solution; The chelating solution, the auxiliary agent and the wetting agent are mixed and compounded, and filtered to obtain a compound filtrate; The compound filtrate is diluted and the pH value is adjusted to 5.5-6.5 to obtain a nutrient solution as a complete nutrient foliar fertilizer.

10. The use according to claim 9, 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. The other heavy metals are all lower than the implementation standard of GB / T 17419-2018 "Foliar Fertilizer 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 both of agricultural organosilicon and sodium lauryl sulfate; And / or, the wetting agent is selected from at least one of triethanolamine, glycerol and urea.

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