A method for efficiently separating lithium and aluminum from lithium ore

Abstract

The present application relates to the technical field of lithium ore recycling, and particularly relates to a method for efficiently separating lithium and aluminum from lithium ore. The method for efficiently separating lithium and aluminum from lithium ore comprises the following steps: mixing organic plant waste residues with lithium mica concentrate powder, performing ball milling, and performing microwave heat treatment to obtain activated lithium mica concentrate; adding the activated lithium mica concentrate into an acid and ethylenediamine composite coordination system, and performing heating acid leaching to obtain a lithium-containing leaching solution and a leaching residue; placing the lithium-containing leaching solution in a polar extraction system to perform extraction, and obtaining a lithium-rich aqueous phase and an aluminum-rich organic phase, wherein the lithium-rich aqueous phase is a lithium-rich solution. The present application solves the problem of low lithium and aluminum separation efficiency in the existing lithium mica processing technology, and also solves the problems of high energy consumption, large acid consumption and large amount of acidic waste liquid in the existing lithium mica processing technology.

Description

Technical Field

[0001] This invention relates to the field of lithium ore recycling technology, specifically to a method for efficiently separating lithium and aluminum from lithium ore. Background Technology

[0002] With the rapid development of new energy batteries and energy storage systems, lithium has become a key strategic metal. Lepidolite is one of my country's important lithium resources, with abundant reserves and wide distribution, representing a potential source for large-scale lithium supply. Currently, the industrial process commonly uses a "high-temperature sulfuric acid roasting-water leaching" method to treat lepidolite: concentrated sulfuric acid is used to roast the ore at 900–950℃, converting lithium into soluble lithium sulfate, followed by water leaching to obtain a lithium-containing leachate. This process can achieve a lithium recovery rate of over 90%, but the roasting process also activates and dissolves associated elements such as aluminum and fluorine from the ore, leading to a decrease in the concentration of Al in the leachate after acid leaching. 3+ With Li + They coexist, but the separation coefficient is low.

[0003] To reduce aluminum content, additional alum precipitants or sulfonating complexing agents are required for aluminum removal, which is not only lengthy and costly but also prone to generating secondary acidic wastewater. If residual aluminum is not thoroughly removed, it will be directly carried into the subsequent concentration-lithium precipitation process, causing the Al content in battery-grade lithium salt products (Li₂CO₃ or LiOH·H₂O) to exceed the standard (high-end battery materials require Al < 0.01%), making it difficult to meet the stringent requirements for high-nickel cathodes and precursors. Furthermore, high-temperature roasting consumes a lot of energy (>3.5 GJ / t-ore), consumes a large amount of acid (sulfuric acid ≥ 0.8 t / t-ore), causes severe equipment corrosion, and generates a large amount of acidic wastewater, resulting in high environmental remediation costs.

[0004] In summary, the existing high-temperature sulfuric acid roasting-multi-stage leaching process suffers from bottlenecks such as low lithium-aluminum separation efficiency, high energy consumption, large acid / alkali consumption, and a large amount of acidic waste liquid. These bottlenecks severely restrict the technological upgrade of green and efficient production of high-end battery-grade lithium salts from lepidolite resources. There is an urgent need to develop new lithium-aluminum separation technologies with high separation efficiency, low energy consumption, low acid consumption, and less acidic waste liquid. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide a method for efficiently separating lithium and aluminum from lithium ore, so as to solve the problem of low lithium and aluminum separation efficiency in the existing lithium mica processing technology, and also to solve the problems of high energy consumption, large acid consumption and large amount of acidic waste liquid in the existing lithium mica processing technology.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for efficiently separating lithium and aluminum from lithium ore includes the following steps:

[0008] S1. Mix organic plant waste residue with lepidolite concentrate powder, ball mill, and microwave heat treat to obtain activated lepidolite concentrate.

[0009] S2. The activated lithium mica concentrate is added to the acid and ethylenediamine complex coordination system, heated and acid-leached to obtain lithium-containing leachate and leaching residue;

[0010] S3. The lithium-containing leachate is extracted in a polar extraction system to obtain a lithium-rich aqueous phase and an aluminum-rich organic phase, wherein the lithium-rich aqueous phase is a lithium-rich solution.

[0011] Based on the above technical means, firstly, organic plant waste (sugarcane bagasse / straw) is mixed with lepidolite and ball-milled, and then subjected to microwave-assisted heat treatment. Using an organic activator-mechanical-thermal coupling activation technology, the carbon in the organic plant waste reduces the silicon in the lepidolite, effectively disrupting the lepidolite crystal structure and thus improving lithium release efficiency. Secondly, a citric acid / tartaric acid-ethylenediamine composite coordination system is used in leaching, where the ligands form stable water-soluble complexes with lithium. Thirdly, a polar extraction system composed of di(2-ethylhexyl)phosphoric acid (D2EHPA) and sulfonated kerosene is designed. By controlling the saponification rate and ratio, aluminum ions are preferentially extracted, and their synergistic effect effectively achieves efficient separation of lithium and aluminum, suitable for treating lepidolite acid leaching solutions with high impurity content. This invention provides a method for efficiently separating lithium and aluminum from lithium ore. It employs a four-stage combined process: activation by organic activator-mechanical-microwave assisted thermal treatment, low-temperature coordination leaching, polar extraction, and high-efficiency adsorption materials. This achieves the goals of "high recovery rate, low energy consumption, and high-purity separation of aluminum and lithium," meeting the requirements of a green circular economy. It effectively solves the problems of low lithium-aluminum separation efficiency in existing lepidolite processing technologies, as well as high energy consumption, large acid consumption, and excessive acidic wastewater.

[0012] Preferably, the organic plant waste is selected from one or two of sugarcane bagasse and straw.

[0013] By using sugarcane bagasse and / or straw as organic activators, the carbon in the organic plant waste reduces the silicon in lepidolite, thereby effectively disrupting the lepidolite crystal structure and improving lithium release efficiency.

[0014] Preferably, the mass ratio of the organic plant waste residue to the lithium mica concentrate powder is 1.0 to 1.5:4.

[0015] Preferably, the temperature of the microwave heat treatment is 200~300℃.

[0016] Preferably, the power of the microwave heat treatment is 800~900W.

[0017] Preferably, the microwave heat treatment is performed by programmed heating, and the rate of programmed heating is 15~20℃ / min;

[0018] Preferably, the holding time for microwave heat treatment is 30-45 minutes.

[0019] The principle behind calcining lepidolite at lower temperatures by adding organic plant waste as a combustion aid and employing ball milling and microwave-assisted heating is as follows: By ball milling, lepidolite is mixed with organic waste such as sugarcane bagasse / straw, refining the particle size to submicron levels and generating numerous lattice dislocations, microcracks, and surface active sites. These defects significantly reduce the lattice integrity of lepidolite, making it more susceptible to phase transitions or decomposition during subsequent heating.

[0020] Simultaneously, during microwave-assisted heat treatment at 200-300℃, the plant waste residue undergoes pyrolysis to produce reducing gases such as CO, H2, and CH4, while releasing a large amount of heat (exothermic decomposition). These gases create a localized reducing environment, which can reduce silicon in the aluminum silicate framework, weaken the Si–O strength, thereby promoting lattice destruction and facilitating the full release of valuable metal elements such as lithium.

[0021] The alkali metals such as potassium and calcium in the waste residue form alkaline oxides or salts after pyrolysis. These salts act as "fluxes" at low temperatures, lowering the melting point of the aluminosilicate phase and further accelerating lattice collapse. Plant waste residue itself contains a large number of polar functional groups (hydroxyl and carboxyl groups) and carbonaceous structures, resulting in high dielectric constants ε′ and dielectric losses ε″, which can generate strong dielectric losses in a microwave field. This high dielectric loss characteristic means that even at an overall temperature of only 200-300℃, the temperature of the waste residue particle surface and the contact area with lepidolite can instantly rise to even higher levels, leading to partial melting or phase transformation of the crystal structure, without needing to raise the overall temperature to the traditional 800-1000℃ calcination temperature. Therefore, adding organic waste residue calcination aids and assisting microwave heating can achieve lepidolite lattice destruction at temperatures far below traditional calcination temperatures, thereby significantly reducing overall calcination energy consumption.

[0022] Preferably, the acid is selected from one or both of citric acid and tartaric acid.

[0023] Preferably, the acid is an aqueous solution containing acid, and the initial concentration of the acid in the aqueous solution is 1.2 mol / L.

[0024] Preferably, when the acid is selected from citric acid and tartaric acid, the molar ratio of citric acid to tartaric acid is 1~2:1.

[0025] Preferably, the mass ratio of the lithium mica concentrate powder to the acid is 1:1.0~1.5.

[0026] Preferably, the temperature of the heating and acid leaching is 70~85℃.

[0027] Preferably, the pH value is adjusted by controlling the amount of ethylenediamine added, so that the pH value of the heated acid leaching is 4.5 to 5.5.

[0028] Preferably, the liquid-to-solid ratio of the heated acid leaching is 4-5 mL: 1 g.

[0029] Preferably, the heating and acid leaching time is 180~240 min.

[0030] Preferably, the stirring rate during the heating and acid leaching is 300-400 rpm.

[0031] The selective leaching using a citric acid / tartaric acid-ethylenediamine complex coordination system, and the mechanism by which the ligands form stable water-soluble complexes with lithium, is as follows:

[0032] 1) Citric acid / tartaric acid mainly exists as C6H5O7 at pH 4.5~5.5. 3- / C4H4O6 2- It exists in a (single deproton) form. Lithium ions form coordinate bonds with their carboxyl groups to generate neutral lithium citrate Li(H₂C₆H₅O₇) / lithium tartrate Li(HC₄H₄O₆). This type of complex is highly soluble and stable in water. The specific reaction equation is as follows:

[0033]

[0034] 2) Ethylenediamine is a typical bidentate ligand, capable of coordinating lithium ions with two nitrogen atoms to form [Li(C2H8N2)]. + The specific reaction equation is as follows:

[0035]

[0036] 3) The mixed ligand system utilizes the carboxyl groups of citric acid / tartaric acid and the bidentate coordination of ethylenediamine, allowing lithium ions to simultaneously accept carboxyl and nitrogen coordination within the same ligand sphere, forming a more stable mixed complex [Li(H2C6H5O7)(C2H8N2)] or [Li(HC4H4O6)(C2H8N2)]. This type of complex maintains good water solubility within a defined pH and temperature range. The specific reaction equations are as follows:

[0037]

[0038] However, under pH conditions of 4.5–5.5, Al 3+ Significant hydrolysis has occurred, producing Al(OH)3 (or aluminum hydroxide colloid), which has low solubility, leading to the free Al... 3+The concentration drops sharply. Therefore, aluminum ions exist almost entirely in precipitated form within this pH range. Furthermore, the stability constant K of the aluminum citrate complex is much lower than the formation constant of the hydroxide produced by its hydrolysis; Al 3+ With a larger radius, it tends to form complexes or hydroxides with high coordination numbers (4~6), while ethylenediamine reacts with Al under weakly acidic conditions. 3+ Its coordination affinity is much lower than that of Li + Due to the coordination properties of ethylenediamine (which is more suitable for coordinating with metals of smaller valence and radius), ethylenediamine primarily forms [Li(C2H8N2)] with lithium in this system. + However, aluminum is not significantly coordinated.

[0039] Preferably, the polar extraction system includes an extractant, a diluent, and a saponifying agent, wherein the extractant is selected from di(2-ethylhexyl) phosphate (D2EHPA), the diluent is selected from sulfonated kerosene, and the saponifying agent is selected from sodium hydroxide (NaOH) solution.

[0040] The NaOH solution is selected from NaOH aqueous solution, and the mass percentage of NaOH in the NaOH aqueous solution is 10%.

[0041] Preferably, the volume ratio of di(2-ethylhexyl) phosphate (D2EHPA) to sulfonated kerosene is 3:7.

[0042] Preferably, the saponification rate of the polar extraction system is 40-65%.

[0043] Preferably, the pH value of the polar extraction system is 7-8.

[0044] Preferably, the overall O / A ratio of the polar extraction system is 2.5~4.5:1.

[0045] In this context, the total ratio O / A represents the volume ratio of the organic phase to the aqueous phase.

[0046] Preferably, the mixing time for the extraction is 15-20 minutes.

[0047] Preferably, the clarification and separation time of the extraction is 20-30 min.

[0048] Preferably, the stirring speed in the extraction tank during the extraction process is 350-450 rpm.

[0049] Preferably, the method further includes: placing the aluminum-rich organic phase in a temperature-pH dual-response back-extraction system for back-extraction to obtain a high-purity aluminum-rich solution.

[0050] Extraction Stage: A polar extraction system composed of D2EHPA and sulfonated kerosene as a diluent was designed to achieve preferential extraction of aluminum ions by controlling the saponification rate and phase ratio. The technical mechanism by which D2EHPA exhibits high selectivity for aluminum ions is as follows:

[0051] Sulfonated kerosene is produced by mixing industrial-grade kerosene with 98% concentrated sulfuric acid at a volume ratio of 1:1 and stirring vigorously for 4 minutes at room temperature. The mixture is then mixed with a 2 mol / L sodium carbonate solution at a volume ratio of 1:1 and stirred vigorously for 5 minutes. Finally, the mixture is allowed to stand and separate into two phases; the upper oil phase is then collected as sulfonated kerosene. This process improves the polarity of the organic phase and its solubility for metal complexes, achieving efficient and selective separation of aluminum and lithium. It also offers advantages such as process flexibility, low energy consumption, and high recovery rate, making it particularly suitable for the deep treatment of lithium mica acid leaching solutions containing high impurities. D2EHPA (HA) exists in the organic phase in an acidic form, and aluminum ions pass through under acidic conditions... It forms a neutral complex Al(HA2)3, which is readily soluble in organic phases due to its neutral charge and low polarity. The high charge density of aluminum's trivalent form results in a coordination constant with D2EHPA that is much higher than that of monovalent lithium, and the naturally occurring separation factor is >30.

[0052] Single-level separation factor ( ) refers to the partition coefficient (D) of the target metal Al in the organic phase. Al ) and the partition coefficient of lithium (Li) in the organic phase (D Li The ratio of ) to:

[0053]

[0054] in, D represents the single-level separation factor. Al D represents the partition coefficient of Al in the organic phase. Li The partition coefficients of Li in the organic phase are represented by the formula. Calculations show that Di represents the extraction rate, and Di represents the partition coefficient of i in the organic phase, where i represents aluminum (Al) or lithium (Li).

[0055] First, preferential extraction of aluminum ions is achieved, Al 3+ Extraction rate ≥99% with Li + The extraction rate is ≤1%. With polarity adjustment of saponification rate (40-65%) and O / A ratio (2.5-4.5:1), the partition coefficient of Al further increases, while the partition coefficient of Li remains low, ultimately yielding α... Al / Li The value is in the range of 30 to 70.

[0056] Under moderate saponification (40-65%), some D2EHPA is converted to Na+.+ Neutralization generates NaD2EHPA, which increases the polarity of the organic phase and raises the system's equilibrium pH, bringing the aluminum extraction rate close to 100%.

[0057] In the mixture of extractant (D2EHPA) and sulfonated kerosene, the saponification rate is mainly achieved by adding liquid alkali (NaOH) and adjusting its dosage, pH, and mixing time. The specific procedures are as follows:

[0058] Calculate and add a certain amount of NaOH aqueous solution to allow it to undergo a saponification reaction with the acidic functional groups in the extractant:

[0059]

[0060] Control the amount of NaOH added to maintain the saponification rate within the target range (e.g., 40-65%), avoiding exceeding 80% (which will cause the organic phase to turn black or become sticky); adjust the system pH (usually around 7.0-8.0), and ensure the molar ratio of NaOH to (HA)₂ matches the set saponification rate through pH monitoring; maintain appropriate temperature and stirring time to ensure a complete and uniform reaction, preventing localized over-saponification. The formula for calculating the saponification rate is as follows:

[0061]

[0062] in, The concentration of NaOH in the NaOH aqueous solution (mol / L) is given. The volume (L) of the NaOH aqueous solution. This represents the concentration (mol / L) of acidic functional groups in the extractant. The volume of the extractant is in liters (L).

[0063] D2EHPA and sulfonated kerosene (high polarity) are mixed at a volume ratio of 3:7 to form a polar system. The high polarity of D2EHPA provides a strong coordination environment for aluminum, while the low polarity of kerosene inhibits lithium transfer, allowing Al(HA)3 to remain well dissolved in the organic phase, while water-soluble lithium complexes have difficulty entering the organic phase.

[0064] An organic / aqueous phase volume ratio of O / A = 2.5~4.5:1 can provide sufficient D2EHPA for aluminum exchange while avoiding excessive organic phase that could lead to decreased compatibility or the formation of a third phase, resulting in the highest single-stage separation factor.

[0065] High saponification degree, polar diluent, and appropriate O / A ratio work together to regulate the polarity, acidity, and coordination ability of the organic phase, enabling aluminum ions to form stable neutral complexes and efficiently transfer to the organic phase, while lithium ions are hardly extracted due to their weak coordination ability and low polarity requirements.

[0066] Preferably, the stripping agent used in the temperature-pH dual-response stripping system is a sulfuric acid solution.

[0067] Preferably, the concentration of sulfuric acid in the sulfuric acid solution is 2 mol / L.

[0068] Preferably, the temperature during the back-extraction process of the temperature-pH dual-response back-extraction system is 60~70℃.

[0069] Preferably, the aqueous phase obtained after back-extraction of the aluminum-rich organic phase in a temperature-pH dual-response back-extraction system has a pH value of 1, and the aqueous phase is the high-purity aluminum-rich solution.

[0070] Preferably, the high-purity aluminum-rich solution can be sold as a chemical product.

[0071] Preferably, the ratio of O / A in the temperature-pH dual-response back-extraction system is 2:1.

[0072] Preferably, the mixing time for the back-extraction is 20-30 minutes.

[0073] Preferably, the separation time for back-extraction is 20-30 minutes.

[0074] By employing a temperature-pH dual-response back-extraction system, directional back-extraction of aluminum (purity >98%) was achieved at 60℃ and pH=1.0.

[0075] Selective back-extraction stage: A temperature-pH dual-response back-extraction system is used to achieve directional back-extraction of aluminum at a temperature of 60–70℃ and pH=1.0. The technical mechanism by which the synergistic effect of temperature and pH can improve back-extraction efficiency is as follows:

[0076] The temperature-pH dual-response back-extraction system achieves efficient and directional back-extraction of aluminum (purity >98%) by: (1) protonating D2EHPA under moderate acidity (pH=1.0) to destroy aluminum D2EHPA complexes; (2) reducing the viscosity of the organic phase, increasing the protonation rate and providing endothermic drive at a high temperature of 60~70°C.

[0077] Preferably, it further includes:

[0078] S4. Adsorbent is used to adsorb the lithium-rich aqueous phase to obtain a high-purity lithium-rich solution.

[0079] Preferably, the Al / Li mass ratio in the high-purity lithium-rich solution is <0.008%.

[0080] Preferably, the high-purity lithium-rich solution can be directly used to produce battery-grade lithium carbonate or lithium hydroxide.

[0081] Preferably, the adsorbent is selected from a composite adsorbent of mesoporous alumina and graphene, and the specific surface area of ​​the composite adsorbent is >800 m². 2 / g, the adsorption capacity of the composite adsorbent is >120mg / g.

[0082] Preferably, the pH value of the lithium-rich aqueous phase is 6 to 6.5.

[0083] Preferably, the lithium-rich aqueous phase is adsorbed using a fixed-bed adsorption column filled with the adsorbent, and the flow rate of the lithium-rich aqueous phase during the adsorption process is 2-3 BV / h (bed volume / hour).

[0084] By utilizing mesoporous alumina / graphene composite adsorbents (specific surface area > 800 m²), 2 Selective adsorption of trace amounts of aluminum (adsorption capacity >120 mg / g) in lithium-rich aqueous phase further improves the purity of lithium in lithium-rich aqueous phase, ultimately achieving advantages such as aluminum / lithium mass ratio <0.008%, total lithium recovery rate >95%, and energy consumption reduced by 35% compared to traditional processes.

[0085] Preferably, after the adsorbent is saturated, it is eluted and regenerated using a dilute hydrochloric acid solution to achieve the recycling of the adsorbent.

[0086] Preferably, the concentration of dilute hydrochloric acid in the dilute hydrochloric acid solution is 0.1 mol / L.

[0087] Preferably, the material-to-ball ratio in the mixed ball mill is 15:1.

[0088] Preferably, the mixing ball milling is carried out in a planetary ball mill to achieve pretreatment of lepidolite concentrate powder, and the planetary ball mill spindle speed of the planetary high-energy ball mill is 350~450 r / min.

[0089] Preferably, the mixing and ball milling time is 60-90 min.

[0090] The technical mechanism of selective adsorption of trace aluminum using mesoporous alumina / graphene composite adsorbents is as follows:

[0091] When the pore walls of alumina intertwine with graphene sheets to form a mesoporous / layered composite network, aluminum ions first coordinate at the hydroxyl sites of alumina, and are subsequently "captured" by the π-electron layer of graphene, forming multi-point bonds (coordination + electrostatic adsorption). This dual adsorption enhances selectivity because Al... 3+ The high charge density of Li makes it easier for both types of active sites to be captured, while other metals (such as Li) are more likely to be captured by both types of active sites. + Na + K +It was excluded due to its low charge or weak coordination tendency. At the same time, its ultra-large specific surface area and pore structure significantly improved adsorption capacity, rate and regeneration efficiency.

[0092] Preferably, the chemical composition and mass percentage of the lepidolite concentrate powder are as follows: Li₂O 3.2 w / %, Al₂O₃ 32.65 w / %, SiO₂ 42.23 w / %, Fe₂O₃ 1.52 w / %, CaO 0.43 w / %, MgO 0.52 w / %, K₂O 6.22 w / %, Na₂O 2.68 w / %, TiO₂ 0.02 w / %, ZrO₂ <0.01 w / %, P₂O₅ 0.26 w / %, SO₃ <0.05 w / %, F 5.72 w / %, ZnO 0.02 w / %, SrO <0.01 w / %, MnO 0.25 w / %, NiO 0.03 w / %, CoO <0.01 w / %, CuO <0.01 w / %, Rb₂O 1.88 w / %, BaO <0.01 w / %. w / %, Cs2O 0.18 w / %, the remainder being other impurities;

[0093] Preferably, the method is used to process the lepidolite concentrate powder so that the lithium leaching rate in the lepidolite concentrate powder is greater than 95%.

[0094] The present invention provides a method for efficiently separating lithium and aluminum from lithium ore, which employs multi-field synergistic extraction and separation technology and achieves efficient separation of lithium and aluminum through a four-stage combined process, comprising the following four stages:

[0095] 1) Pretreatment activation module: By mixing organic plant waste (sugarcane bagasse / straw) with lepidolite and ball milling, the organic activator-mechanical-thermal coupling activation technology is used to carry out microwave-assisted heat treatment at 200-300℃. Under this condition, the carbon in the organic plant waste can reduce the silicon in the lepidolite, thereby destroying the lepidolite crystal structure and improving the lithium release efficiency.

[0096] 2) Selective leaching stage: Leaching is carried out using a citric acid / tartaric acid-ethylenediamine complex coordination system (molar ratio 3:1) at a pH of 4.5~5.5 and a temperature of 70~85℃. The ligands form stable water-soluble complexes with lithium.

[0097] 3) Extraction stage: A polar extraction system consisting of di(2-ethylhexyl) phosphate (D2EHPA) and sulfonated kerosene (volume ratio 3:7) was designed. The aluminum ion preferential extraction (single-stage separation factor >30) was achieved by controlling the saponification rate (40~65%) and the ratio (O / A=2.5~4.5:1).

[0098] 4) Selective back-extraction stage: A temperature-pH dual-response back-extraction system is used to achieve directional back-extraction of aluminum (purity >98%) at a temperature of 60℃ and pH=1.0.

[0099] 5) Deep purification stage: Utilizing mesoporous alumina / graphene composite adsorbents (specific surface area > 800 m²) 2 Selective adsorption of trace amounts of aluminum (adsorption capacity > 120 mg / g) was performed.

[0100] The process for efficiently separating lithium and aluminum from lithium ore according to the present invention effectively achieves the advantages of aluminum / lithium mass ratio <0.008%, total lithium recovery rate >92%, and energy consumption reduced by 35% compared with traditional processes. It is suitable for the treatment of lepidolite acid leaching solution with high impurity content.

[0101] The beneficial effects of this invention are:

[0102] The present invention discloses a method for efficiently separating lithium and aluminum from lithium ore. First, organic plant waste (sugarcane bagasse / straw) is mixed with lepidolite and ball-milled, followed by microwave-assisted heat treatment using an organic activator-mechanical-thermal coupling activation technology. This allows the carbon in the organic plant waste to reduce the silicon in the lepidolite, effectively disrupting the lepidolite crystal structure and thus improving lithium release efficiency. Second, a citric acid / tartaric acid-ethylenediamine composite coordination system is used for leaching, where the ligands form stable water-soluble complexes with lithium. Third, a polar extraction system composed of di(2-ethylhexyl)phosphoric acid (D2EHPA) and sulfonated kerosene is designed, and aluminum ion extraction is preferentially achieved by controlling the saponification rate and specific gravity. Fourth, a temperature-pH dual-response back-extraction system is used to achieve directional back-extraction of aluminum (purity >98%) at 60℃ and pH=1.0. Finally, a mesoporous alumina / graphene composite adsorbent (specific surface area >800 m²) is used. 2 Selective adsorption of trace amounts of aluminum (adsorption capacity >120 mg / g) is achieved using a synergistic effect, effectively realizing the efficient separation of lithium and aluminum. This method is suitable for treating lepidolite acid leaching solutions with high impurity content. It has significant application value in the field of lithium ore recycling technology. Detailed Implementation

[0103] 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.

[0104] The chemical composition and mass percentage of the lepidolite concentrate powder used in the following examples are as follows: Li₂O 3.2 w / %, Al₂O₃ 32.65 w / %, SiO₂ 42.23 w / %, Fe₂O₃ 1.52 w / %, CaO 0.43 w / %, MgO 0.52 w / %, K₂O 6.22 w / %, Na₂O 2.68 w / %, TiO₂ 0.02 w / %, ZrO₂ <0.01 w / %, P₂O₅ 0.26 w / %, SO₃ <0.05 w / %, F 5.72 w / %, ZnO 0.02 w / %, SrO <0.01 w / %, MnO 0.25 w / %, NiO 0.03 w / %, CoO <0.01 w / %, CuO <0.01 w / %, Rb₂O 1.88 w / %, BaO <0.01 w / %. w / %, Cs2O 0.18 w / %, the remainder being other impurities.

[0105] Example 1

[0106] A method for efficiently separating lithium and aluminum from lithium ore includes the following steps:

[0107] S1. Add 1000g of lithium mica concentrate powder to the planetary ball mill, then add 250g of straw. The material-to-ball ratio is 15:1. Control the rotation speed of the planetary ball mill to 350rpm and the grinding time to 60min.

[0108] The ball-milled lepidolite concentrate powder was subjected to microwave heat treatment with a microwave power of 800W, a microwave heating temperature of 200℃, a microwave heating rate of 15℃ / min, and a holding time of 30min to obtain activated lepidolite concentrate powder.

[0109] S2. Add the activated lithium mica concentrate powder obtained in S1 to the citric acid aqueous solution-ethylenediamine complex coordination system, heat and leach to obtain a mixed leachate;

[0110] The initial concentration of citric acid in the citric acid aqueous solution was 1.2 mol / L, and the amount of citric acid aqueous solution used was 1000 g. The pH value of the acid leaching was adjusted to 5.5 by adding ethylenediamine, the acid leaching temperature was 70℃, the liquid-to-solid ratio of the acid leaching was 4 mL: 1 g, the acid leaching time was 180 min, and the stirring rate was 300 rpm.

[0111] The obtained mixed leachate is separated into solid and liquid components by pressure filtration to obtain lithium-containing leachate and leachate residue (mainly aluminosilicate residue). The leachate residue can be used as a building material raw material.

[0112] S3. The lithium-containing leachate obtained in S2 is placed in a polar extraction system for extraction to obtain a lithium-rich aqueous phase and an aluminum-rich organic phase. The lithium-rich aqueous phase is the lithium-rich solution.

[0113] The polar extraction system includes the extractant di(2-ethylhexyl) phosphate (D2EHPA), the diluent sulfonated kerosene, and a NaOH aqueous solution with a mass percentage of 10% as the saponifying agent. The volume ratio of D2EHPA to sulfonated kerosene is 3:7. The saponification rate of the polar extraction system is 50%, the pH value is 7.0, and the overall O / A ratio is 3.2:1.

[0114] The polar extraction system preferentially transfers aluminum ions from the aqueous phase to the organic phase, while lithium ions remain in the aqueous phase. The stirring speed of the extraction tank is 350 rpm, the solution mixing time is 15 min, and the solution clarification time is 20 min.

[0115] S4. Using a temperature-pH dual-response back-extraction system, the aluminum-rich organic phase obtained in S3 is used to achieve directional back-extraction of aluminum, resulting in a high-purity aluminum-rich solution.

[0116] The stripping agent in the temperature-pH dual-response stripping system is a 2 mol / L H2SO4 aqueous solution. By controlling the amount of acid used, the final pH of the aqueous phase after stripping is 1.0. The stripping temperature is 60℃, the ratio (O / A) of the temperature-pH dual-response stripping system is 2:1, the mixing time of the solution during the stripping process is 20 min, and the separation time of the solution during the stripping process is 20 min. The aqueous phase is a high-purity aluminum sulfate solution, which can be sold as a chemical product. The organic phase is regenerated and returned to the extraction section for recycling.

[0117] S5. The lithium-rich aqueous phase obtained in S3 is subjected to a composite adsorbent filled with mesoporous alumina and graphene (specific surface area > 800 m²). 2 A fixed-bed adsorption column with an adsorption capacity >120 mg / g was used to selectively adsorb trace amounts of aluminum to obtain a high-purity lithium-rich solution.

[0118] The lithium-rich aqueous phase has a pH of 6.0 and a flow rate of 2 BV / h (bed volume / hour) through the fixed bed adsorption column.

[0119] After the composite adsorbent of mesoporous alumina and graphene becomes saturated, it is eluted and regenerated with a 0.1 mol / L dilute hydrochloric acid aqueous solution, thus achieving recycling.

[0120] Example 2

[0121] A method for efficiently separating lithium and aluminum from lithium ore includes the following steps:

[0122] S1. Add 1000g of lithium mica concentrate powder into a planetary ball mill, then add 375g of bagasse, with a material-to-ball ratio of 15:1. Control the rotation speed of the planetary ball mill at 400 rpm and the grinding time at 80 min.

[0123] The ball-milled lepidolite concentrate powder was subjected to microwave heat treatment with a microwave power of 850W, a microwave heating temperature of 250℃, a microwave heating rate of 15℃ / min, and a holding time of 30min to obtain activated lepidolite concentrate powder.

[0124] S2. Add the activated lithium mica concentrate powder obtained in S1 to the tartaric acid aqueous solution-ethylenediamine complex coordination system, heat and leach to obtain a mixed leachate;

[0125] The initial concentration of tartaric acid in the tartaric acid aqueous solution was 1.2 mol / L, and the amount of tartaric acid aqueous solution used was 1200 g. The pH value of the acid leaching was adjusted to 5.0 by adding ethylenediamine, the acid leaching temperature was 80℃, the liquid-solid ratio of the acid leaching was 4 mL: 1 g, the acid leaching time was 200 min, and the stirring rate was 350 rpm.

[0126] The obtained mixed leachate is separated into solid and liquid components by pressure filtration to obtain lithium-containing leachate and leachate residue (mainly aluminosilicate residue). The leachate residue can be used as a building material raw material.

[0127] S3. The lithium-containing leachate obtained in S2 is placed in a polar extraction system for extraction to obtain a lithium-rich aqueous phase and an aluminum-rich organic phase. The lithium-rich aqueous phase is the lithium-rich solution.

[0128] The polar extraction system includes the extractant di(2-ethylhexyl) phosphate (D2EHPA), the diluent sulfonated kerosene, and the saponifying agent NaOH. The volume ratio of D2EHPA to sulfonated kerosene is 3:7. The saponification rate of the polar extraction system is 65%, the pH value is 7.5, and the overall O / A ratio is 2.5:1.

[0129] The polar extraction system preferentially transfers aluminum ions from the aqueous phase to the organic phase, while lithium ions remain in the aqueous phase. The stirring speed of the extraction tank is 400 rpm, the solution mixing time is 20 min, and the solution clarification time is 25 min.

[0130] S4. Using a temperature-pH dual-response back-extraction system, the aluminum-rich organic phase obtained in S3 is used to achieve directional back-extraction of aluminum, resulting in a high-purity aluminum-rich solution.

[0131] The stripping agent in the temperature-pH dual-response stripping system is a 2 mol / L H2SO4 aqueous solution. By controlling the amount of acid used, the final pH of the aqueous phase after stripping is 1.0. The stripping temperature is 65℃, the ratio (O / A) of the temperature-pH dual-response stripping system is 2:1, the mixing time of the solution during the stripping process is 25 min, and the separation time of the solution during the stripping process is 25 min. The aqueous phase is a high-purity aluminum sulfate solution, which can be sold as a chemical product. The organic phase is regenerated and returned to the extraction section for recycling.

[0132] S5. The lithium-rich aqueous phase obtained in S3 is subjected to a composite adsorbent filled with mesoporous alumina and graphene (specific surface area > 800 m²). 2 A fixed-bed adsorption column with an adsorption capacity >120 mg / g was used to selectively adsorb trace amounts of aluminum to obtain a high-purity lithium-rich solution.

[0133] The lithium-rich aqueous phase has a pH of 6.5 and a flow rate of 2 BV / h (bed volume / hour) through the fixed bed adsorption column.

[0134] After the composite adsorbent of mesoporous alumina and graphene becomes saturated, it is eluted and regenerated with a 0.1 mol / L dilute hydrochloric acid aqueous solution, thus achieving recycling.

[0135] Example 3

[0136] A method for efficiently separating lithium and aluminum from lithium ore includes the following steps:

[0137] S1. Add 1000g of lithium mica concentrate powder to the planetary ball mill, then add 375g of straw. The material-to-ball ratio is 15:1. Control the rotation speed of the planetary ball mill to 450rpm and the grinding time to 90min.

[0138] The ball-milled lepidolite concentrate powder was subjected to microwave heat treatment with a microwave power of 900W, a microwave heating temperature of 300℃, a microwave heating rate of 20℃ / min, and a holding time of 45min to obtain activated lepidolite concentrate powder.

[0139] S2. The activated lithium mica concentrate powder obtained in S1 is added to a mixed aqueous solution of citric acid and tartaric acid-ethylenediamine complex coordination system, and then heated for acid leaching to obtain a mixed leachate.

[0140] The initial concentrations of citric acid and tartaric acid in the mixed aqueous solution were both 1.2 mol / L, the molar ratio of citric acid to tartaric acid was 1:1, and the total volume of the mixed aqueous solution of citric acid and tartaric acid was 1300 g. The pH value of the acid leaching was adjusted to 4.5 by adding ethylenediamine, the acid leaching temperature was 85℃, the liquid-to-solid ratio of the acid leaching was 4 mL:1 g, the acid leaching time was 240 min, and the stirring rate was 400 rpm.

[0141] The obtained mixed leachate is separated into solid and liquid components by pressure filtration to obtain lithium-containing leachate and leachate residue (mainly aluminosilicate residue). The leachate residue can be used as a building material raw material.

[0142] S3. The lithium-containing leachate obtained in S2 is placed in a polar extraction system for extraction to obtain a lithium-rich aqueous phase and an aluminum-rich organic phase. The lithium-rich aqueous phase is the lithium-rich solution.

[0143] The polar extraction system includes the extractant di(2-ethylhexyl) phosphate (D2EHPA), the diluent sulfonated kerosene, and the saponifying agent NaOH solution. The volume ratio of D2EHPA to sulfonated kerosene is 3:7. The saponification rate of the polar extraction system is 40%, the pH value is 8.0, and the overall O / A ratio is 4.5:1.

[0144] The polar extraction system preferentially transfers aluminum ions from the aqueous phase to the organic phase, while lithium ions remain in the aqueous phase. The stirring speed of the extraction tank is 450 rpm, the solution mixing time is 20 min, and the solution clarification time is 30 min.

[0145] S4. Using a temperature-pH dual-response back-extraction system, the aluminum-rich organic phase obtained in S3 is used to achieve directional back-extraction of aluminum, resulting in a high-purity aluminum-rich solution.

[0146] The stripping agent in the temperature-pH dual-response stripping system is a 2 mol / L H2SO4 aqueous solution. By controlling the amount of acid used, the final pH of the aqueous phase after stripping is 1.0. The stripping temperature is 70℃, the ratio (O / A) of the temperature-pH dual-response stripping system is 2:1, the mixing time of the solution during the stripping process is 30 min, and the separation time of the solution during the stripping process is 30 min. The aqueous phase is a high-purity aluminum sulfate solution, which can be sold as a chemical product. The organic phase is regenerated and returned to the extraction section for recycling.

[0147] S5. The lithium-rich aqueous phase obtained in S3 is subjected to a composite adsorbent filled with mesoporous alumina and graphene (specific surface area > 800 m²). 2 A fixed-bed adsorption column with an adsorption capacity >120 mg / g was used to selectively adsorb trace amounts of aluminum to obtain a high-purity lithium-rich solution.

[0148] The lithium-rich aqueous phase has a pH of 6.5 and a flow rate of 3 BV / h (bed volume / hour) through the fixed bed adsorption column.

[0149] After the composite adsorbent of mesoporous alumina and graphene becomes saturated, it is eluted and regenerated with a 0.1 mol / L dilute hydrochloric acid aqueous solution, thus achieving recycling.

[0150] Comparative Example 1

[0151] A method for separating lithium aluminum from lithium ore includes the following steps:

[0152] S1. Add 1000g of lithium mica concentrate powder into a planetary ball mill with a material-to-ball ratio of 15:1. Control the rotation speed of the planetary ball mill at 450rpm and the grinding time at 90min.

[0153] The ball-milled lepidolite concentrate powder was placed in a muffle furnace and calcined at 900℃ for 120 minutes to obtain the calcined product, which is the activated lepidolite concentrate.

[0154] S2. The lepidolite concentrate obtained in S1 is added to a mixed aqueous solution of citric acid and tartaric acid-ethylenediamine complex coordination system, and then heated for acid leaching to obtain a mixed leachate.

[0155] The initial concentrations of citric acid and tartaric acid in the mixed aqueous solution were both 1.2 mol / L, the molar ratio of citric acid to tartaric acid was 1:1, and the total volume of the mixed aqueous solution of citric acid and tartaric acid was 1300 g. The pH value of the acid leaching was adjusted to 4.5 by adding ethylenediamine, the acid leaching temperature was 85℃, the liquid-to-solid ratio of the acid leaching was 4 mL:1 g, the acid leaching time was 240 min, and the stirring rate was 400 rpm.

[0156] The obtained mixed leachate is separated into solid and liquid components by pressure filtration to obtain lithium-containing leachate and leachate residue (mainly aluminosilicate residue). The leachate residue can be used as a building material raw material.

[0157] S3. The lithium-containing leachate obtained in S2 is placed in a polar extraction system for extraction to obtain a lithium-rich aqueous phase and an aluminum-rich organic phase. The lithium-rich aqueous phase is the lithium-rich solution.

[0158] The polar extraction system includes the extractant di(2-ethylhexyl) phosphate (D2EHPA), the diluent sulfonated kerosene, and the saponifying agent NaOH solution. The volume ratio of D2EHPA to sulfonated kerosene is 3:7. The saponification rate of the polar extraction system is 40%, the pH value is 8.0, and the overall O / A ratio is 3.6:1.

[0159] The stirring speed in the extraction tank was 450 rpm, the solution mixing time was 20 min, and the solution clarification time was 30 min.

[0160] S4. Using a temperature-pH dual-response back-extraction system, the aluminum-rich organic phase obtained in S3 is used to achieve directional back-extraction of aluminum, resulting in a high-purity aluminum-rich solution.

[0161] The stripping agent in the temperature-pH dual-response stripping system is a 2 mol / L H2SO4 aqueous solution. By controlling the amount of acid used, the final pH of the aqueous phase after stripping is 1.0. The stripping temperature is 70℃, the ratio (O / A) of the temperature-pH dual-response stripping system is 2:1, the mixing time of the solution during the stripping process is 30 min, and the separation time of the solution during the stripping process is 30 min. The aqueous phase is a high-purity aluminum sulfate solution, which can be sold as a chemical product. The organic phase is regenerated and returned to the extraction section for recycling.

[0162] S5. The lithium-rich aqueous phase obtained in S3 is subjected to a composite adsorbent filled with mesoporous alumina and graphene (specific surface area > 800 m²). 2 A fixed-bed adsorption column with an adsorption capacity >120 mg / g was used to selectively adsorb trace amounts of aluminum to obtain a high-purity lithium-rich solution.

[0163] The lithium-rich aqueous phase has a pH of 6.5 and a flow rate of 3 BV / h (bed volume / hour) through the fixed bed adsorption column.

[0164] After the composite adsorbent of mesoporous alumina and graphene becomes saturated, it is eluted and regenerated with a 0.1 mol / L dilute hydrochloric acid aqueous solution, thus achieving recycling.

[0165] Comparative Example 2

[0166] A method for separating lithium aluminum from lithium ore includes the following steps:

[0167] S1. Add 1000g of lithium mica concentrate powder to the planetary ball mill, then add 375g of straw. The material-to-ball ratio is 15:1. Control the rotation speed of the planetary ball mill to 450rpm and the grinding time to 90min.

[0168] The ball-milled lepidolite concentrate powder was subjected to microwave heat treatment with a microwave power of 900W, a microwave heating temperature of 300℃, a microwave heating rate of 20℃ / min, and a holding time of 45min to obtain activated lepidolite concentrate.

[0169] S2. Add the lithium mica concentrate obtained in S1 to an aqueous sulfuric acid solution, heat and leach to obtain a mixed leachate;

[0170] The initial concentration of sulfuric acid in the sulfuric acid aqueous solution was 1.2 mol / L, the amount of sulfuric acid used was 1300 g, the acid leaching temperature was 85℃, the liquid-to-solid ratio of acid leaching was 4 mL: 1 g, the acid leaching time was 240 min, and the stirring rate was 400 rpm.

[0171] The obtained mixed leachate is separated into solid and liquid components by pressure filtration to obtain lithium-containing leachate and leachate residue (mainly aluminosilicate residue). The leachate residue can be used as a building material raw material.

[0172] S3. The lithium-containing leachate obtained in S2 is placed in a polar extraction system for extraction to obtain a lithium-rich aqueous phase and an aluminum-rich organic phase. The lithium-rich aqueous phase is the lithium-rich solution.

[0173] The polar extraction system includes the extractant di(2-ethylhexyl) phosphate (D2EHPA), the diluent sulfonated kerosene, and the saponifying agent NaOH solution. The volume ratio of D2EHPA to sulfonated kerosene is 3:7. The saponification rate of the polar extraction system is 50%, the pH value is 8.0, and the overall O / A ratio is 8.6:1.

[0174] The polar extraction system preferentially transfers aluminum ions from the aqueous phase to the organic phase, while lithium ions remain in the aqueous phase. The stirring speed of the extraction tank is 450 rpm, the solution mixing time is 20 min, and the solution clarification time is 30 min.

[0175] S4. Using a temperature-pH dual-response back-extraction system, the aluminum-rich organic phase obtained in S3 is used to achieve directional back-extraction of aluminum, resulting in a high-purity aluminum-rich solution.

[0176] The stripping agent in the temperature-pH dual-response stripping system is a 2 mol / L H2SO4 aqueous solution. By controlling the amount of acid used, the final pH of the aqueous phase after stripping is 1.0. The stripping temperature is 70℃, the ratio (O / A) of the temperature-pH dual-response stripping system is 2:1, the mixing time of the solution during the stripping process is 30 min, and the separation time of the solution during the stripping process is 30 min. The aqueous phase is a high-purity aluminum sulfate solution, which can be sold as a chemical product. The organic phase is regenerated and returned to the extraction section for recycling.

[0177] S5. The lithium-rich aqueous phase obtained in S3 is subjected to a composite adsorbent filled with mesoporous alumina and graphene (specific surface area > 800 m²). 2 A fixed-bed adsorption column with an adsorption capacity >120 mg / g was used to selectively adsorb trace amounts of aluminum to obtain a high-purity lithium-rich solution.

[0178] The lithium-rich aqueous phase has a pH of 6.5 and a flow rate of 3 BV / h (bed volume / hour) through the fixed bed adsorption column.

[0179] After the composite adsorbent of mesoporous alumina and graphene becomes saturated, it is eluted and regenerated with a 0.1 mol / L dilute hydrochloric acid aqueous solution, thus achieving recycling.

[0180] Comparative Example 3

[0181] A traditional lithium extraction technology using lithium mica acid roasting includes the following steps:

[0182] S1. Mix 1000 g of lepidolite concentrate powder with 98% concentrated sulfuric acid, then place the mixture in a muffle furnace and acidify and roast at 900℃ for 120 min to obtain the roasted product; wherein the mass ratio of lepidolite concentrate powder to 98% concentrated sulfuric acid is 1:2.

[0183] S2. The lithium mica concentrate obtained in S1 is added to a water bath and leached using a traditional three-stage countercurrent water leaching method. The leaching liquid-to-solid ratio is 4 mL:1 g, the leaching temperature is 90 °C, the leaching time is 240 min, the stirring speed is 400 rpm, and the mixture is filtered to obtain lithium-containing leaching solution and leaching residue.

[0184] S3. Add Ca(OH)2 to the lithium-containing leachate from S2 to adjust the pH value to above 12, thereby removing aluminum / fluorine impurities with the precipitant and obtaining the lithium-containing leachate after impurity removal.

[0185] S4. Evaporate and concentrate the lithium-containing leachate after impurity removal by 4 times, then add 130g of sodium carbonate lithium precipitation agent to carry out the lithium precipitation reaction, and filter to obtain lithium carbonate product and remaining filtrate.

[0186] Detection and Analysis

[0187] 1. Determination of the content of Li2O and Al2O3 in the leaching residue, the pH value of the lithium-containing leachate, the yield of the leaching residue, and the leaching rate of Li2O / Al2O3 in the lithium mica concentrate powder.

[0188] The leaching rates of Li2O and Al2O3 in lepidolite concentrate powder are calculated using formulas (I) and (II):

[0189] The leaching rate of Li2O = [volume of lithium-containing leachate (L) × concentration of Li2O in lithium-containing leachate (g / L)] / [Li2O content in lepidolite concentrate (%) × mass of lepidolite concentrate (g)] × 100% (I)

[0190] The leaching rate of Al2O3 = [volume of lithium-containing leachate (L) × concentration of Al2O3 in lithium-containing leachate (g / L)] / [Al2O3 content in lepidolite concentrate (%) × mass of lepidolite concentrate (g)] × 100% (II)

[0191] The concentration of Li2O in the lithium-containing leachate was measured by standard atomic absorption spectrophotometry; the concentration of Al2O3 in the lithium-containing leachate was measured by standard inductively coupled plasma (ICP).

[0192] The formula for calculating the yield of the leaching residue is shown in equation (III):

[0193] Leaching residue yield (%) = [100% × dry weight of leaching residue (g)] / dry weight of lepidolite concentrate powder (g) (III)

[0194] The pH value of the lithium leaching solution was measured using a pH meter.

[0195] The results of the determination of the content, yield, leaching rate and pH value of each substance are shown in Table 1.

[0196] Table 1 shows the results of the determination of the content, yield, leaching rate and pH value of each substance.

[0197]

[0198] As can be seen from the comparative analysis in Table 1, by activating the lithium mica concentrate through an organic activator-mechanical-thermal coupling in the early stage, and then using the citric acid / tartaric acid-ethylenediamine composite coordination system for selective acid leaching of lithium, the leaching rate of Li2O can be above 95%, and the leaching rate of aluminum can be <20%.

[0199] By comparing Example 3 and Comparative Example 1, it can be seen that the method of selectively extracting lithium by adding an organic activator-mechanical-thermal coupling activation pretreatment process to lepidolite, followed by selective acid leaching using a citric acid / tartaric acid-ethylenediamine composite coordination system, resulted in an 8.24% increase in the leaching rate of Li2O and a 13.82% decrease in the leaching rate of Al2O3 compared to pretreatment without adding an activator and microwave heating, or leaching using only traditional organic acid.

[0200] Comparing Example 3 and Comparative Example 2, it can be seen that Comparative Example 2, using only the traditional sulfuric acid leaching process, achieved an aluminum leaching rate as high as 41.61%, which significantly increased the cost of subsequent lithium-aluminum separation and impurity removal. In contrast, Example 3, employing a citric acid / tartaric acid-ethylenediamine composite coordination system for selective leaching, increased the Li2O leaching rate in the leachate by 14.26% compared to traditional sulfuric acid leaching, while reducing the Al2O3 leaching rate by 29.01%.

[0201] As can be seen from Comparative Example 3, the traditional sulfuric acid 900℃ high-temperature roasting-water leaching process achieves a lithium leaching rate of 79.35% and an aluminum leaching rate as high as 57.02%, which leads to higher costs for subsequent lithium-aluminum separation and impurity removal. Comparing Example 3 and Comparative Example 3, it is evident that when Example 3 activates the lepidolite concentrate using an organic activator-mechanical-thermal coupling, and then selectively leaches lithium using a citric acid / tartaric acid-ethylenediamine composite coordination system, the Li2O content in the leachate is increased by 18.42% compared to the traditional sulfuric acid 900℃ high-temperature roasting-water leaching process in Comparative Example 3, while the Al2O3 leaching rate is reduced by 44.98%.

[0202] In summary, this invention significantly improves the Li₂O leaching rate by adding an organic activator-mechanical-thermal coupling to activate lepidolite concentrate, followed by selective leaching of lithium using a citric acid / tartaric acid-ethylenediamine composite coordination system, while keeping the aluminum leaching rate below 20%. Furthermore, it achieves lithium conversion in lepidolite at relatively low temperatures and under mild acidic conditions, saving energy and reducing production costs for subsequent impurity removal.

[0203] 2) Li + Extraction rate and Al 3+ Extraction rate determination

[0204] Li + Extraction rate and Al 3+ The formula for calculating the extraction rate is as follows:

[0205] Al 3+ Extraction rate = [(Al in aluminum-rich organic phase)] 3+ Concentration (g / L) * Volume of aluminum-rich organic phase (L) / (Al in lithium-containing leachate) 3+ [Concentration (g / L) * Volume of lithium-containing leachate (L)] × 100%

[0206] Li + Extraction rate = [(Li in aluminum-rich organic phase)] + Concentration (g / L) * Volume of aluminum-rich organic phase (L) / (Li in lithium-containing leachate) + [Concentration (g / L) * Volume of lithium-containing leachate (L)] × 100%

[0207] Aluminum / Lithium mass ratio = [Mass of aluminum (g) in lithium-rich aqueous phase] / [Mass of lithium (g) in lithium-rich aqueous phase]

[0208] Among them, Al in the aluminum-rich organic phase 3+ There are two methods for determining the concentration of Al: the first is to measure the Al concentration in the lithium-containing leachate before extraction. 3+ The concentration of Al was determined after extraction and then measured in the aqueous phase. 3+The concentration of Al in the lithium-containing leachate was then determined. 3+ The concentration of Al in the aqueous phase after extraction is subtracted from the concentration of Al. 3+ The concentration of Al in the aluminum-rich organic phase was determined. 3+ The first method involves adjusting the concentration of aluminum; the second method involves taking an appropriate amount of aluminum-rich organic phase, adding perchloric acid, and oxidizing the organic matter to obtain an Al-containing product free of organic matter. 3+ The aluminum in the organic phase can be obtained by analyzing the aqueous solution and then measuring it using standard inductively coupled plasma (ICP). 3+ The concentration.

[0209] Al in lithium-containing leachate 3+ The concentration was measured using the standard inductively coupled plasma (ICP) method.

[0210] Li in aluminum-rich organic phase + The method for determining the concentration of Li is as follows: Take an appropriate amount of aluminum-rich organic phase, add perchloric acid to destroy the organic matter, and obtain Li-containing organic matter-free product. + The Li in the aluminum-rich organic phase can be obtained by measuring the aqueous solution using atomic absorption spectrophotometry. + The concentration.

[0211] Li in lithium-containing leachate + The concentration was measured using atomic absorption spectrophotometry.

[0212] The measurement results are shown in Table 2.

[0213] Table 2 Li + And Al 3+ Extraction rate determination results

[0214]

[0215] As shown in Table 2, Examples 1 to 3 effectively achieved lithium-aluminum separation in lepidolite leachate by combining organic activator-mechanical-thermal coupling activation technology with a polar extraction system. The final aluminum / lithium mass ratio was <0.008%, which is much lower than the lithium-aluminum separation process used in Comparative Examples 1 and 2. This high-purity lithium-rich solution can be directly used to produce battery-grade lithium carbonate or lithium hydroxide. The aluminum extraction rate in the organic phase can reach over 99%, which is higher than the traditional lithium-aluminum separation process. The aqueous phase after back-extraction is a high-purity aluminum sulfate solution, which can be sold as a chemical product.

[0216] 3) Determination of lithium and aluminum separation and impurity removal components in the leachate

[0217] The lithium-rich solution obtained in S3 of Example 3 and the lithium-containing leachate obtained in S3 of Comparative Example 3 were subjected to compositional analysis using inductively coupled plasma atomic emission spectrometry (ICP), atomic absorption spectrophotometry (AAS), gas chromatography-mass spectrometry (GC-MS), and automatic potentiometric titration, respectively. The results are shown in Tables 3 and 4.

[0218] Table 3 shows the main components of the lithium-rich solution obtained after extraction in Example 3.

[0219]

[0220] Note: The organic component is citrate ion C6H5O7. 3- tartrate ion C4H4O6 2- Ethylenediamine C2H8N2.

[0221] Table 4 shows the main components of the lithium-containing leachate after impurity removal in Comparative Example 3.

[0222]

[0223] Comparative analysis of Tables 3 and 4 shows that the lithium-rich solution obtained in S3 of Example 3 has a Li concentration of 12.18 g / L. The main impurities include SiO2, F, Al, Fe, and Ca, while other impurities include Mg and Mn. Compared to the traditional sulfuric acid 900℃ high-temperature roasting-water leaching-Ca(OH)2 impurity removal process, the purity of the leachate is increased by more than 50%. The contents of the main impurities Al and Fe are reduced by more than 97%, and the content of SiO2 is reduced by 50.69%. The contents of other impurity elements are all below 0.01 g / L. Furthermore, the traditional sulfuric acid 900℃ high-temperature roasting-water leaching-Ca(OH)2 impurity removal process results in an aluminum / lithium mass ratio of 0.31 in the lithium-containing leachate after impurity removal, which is significantly higher than the lithium-aluminum separation process combining organic activator-mechanical-thermal coupling activation technology and polar extraction used in Examples 1 to 3.

[0224] The above results demonstrate that a polar extraction system effectively separates lithium and aluminum from lepidolite acid leaching solutions, significantly reducing impurities in the leachate with an aluminum / lithium mass ratio of <0.008%. This high-purity lithium-rich solution can be directly used to produce battery-grade lithium carbonate or lithium hydroxide. Furthermore, the high-purity aluminum sulfate solution obtained after back-extraction can be sold as a chemical product, thus achieving a high degree of comprehensive resource recovery.

[0225] In addition, the process activates lepidolite concentrate by adding an organic activator in the early stage through mechanical-thermal coupling, and the roasting temperature is only 200~300℃. This can destroy the lepidolite lattice under conditions far lower than the traditional roasting temperature, thereby significantly reducing the overall roasting energy consumption.

[0226] In summary, the method for efficiently separating lithium and aluminum from lithium ore according to the present invention firstly involves ball milling organic plant waste (sugarcane bagasse / straw) with lepidolite, followed by activation using an organic activator-mechanical-thermal coupling technology, and then microwave-assisted heat treatment. This process reduces the silicon in the lepidolite from the carbon in the organic plant waste, effectively disrupting the lepidolite crystal structure and thus improving lithium release efficiency. Secondly, a citric acid / tartaric acid-ethylenediamine composite coordination system is used for leaching, where the ligands form stable water-soluble complexes with lithium. Thirdly, a polar extraction system composed of di(2-ethylhexyl)phosphoric acid (D2EHPA) and sulfonated kerosene is designed, and aluminum ion preferential extraction is achieved by controlling the saponification rate and specific gravity. Fourthly, a temperature-pH dual-response back-extraction system is used to achieve directional back-extraction of aluminum (purity >98%) at 60℃ and pH=1.0. Finally, a mesoporous alumina / graphene composite adsorbent (specific surface area >800m²) is used. 2 Selective adsorption of trace amounts of aluminum (adsorption capacity >120 mg / g) is achieved using a synergistic effect, effectively realizing the efficient separation of lithium and aluminum. This method is suitable for treating lepidolite acid leaching solutions with high impurity content. It has significant application value in the field of lithium ore recycling technology.

[0227] 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 separating lithium aluminum from lithium ore, characterized in that, Includes the following steps: S1. Mix organic plant waste residue with lepidolite concentrate powder, ball mill, and microwave heat treat to obtain activated lepidolite concentrate. S2. The activated lithium mica concentrate is added to an acid and ethylenediamine complex coordination system and heated for acid leaching to obtain a lithium-containing leachate; the acid is selected from one or two of citric acid and tartaric acid, and the pH value of the heated acid leaching is 4.5~5.5; S3. The lithium-containing leachate is extracted in a polar extraction system to obtain a lithium-rich aqueous phase and an aluminum-rich organic phase, wherein the lithium-rich aqueous phase is a lithium-rich solution.

2. The method for separating lithium and aluminum from lithium ore according to claim 1, characterized in that, The organic plant waste is selected from one or two of sugarcane bagasse and straw; And / or, the mass ratio of the organic plant waste residue to the lithium mica concentrate powder is 1.0 to 1.5:4; And / or, the temperature of the microwave heat treatment is 200~300℃; And / or, the power of the microwave heat treatment is 800~900W; And / or, the microwave heat treatment is performed by programmed heating, and the programmed heating rate is 15~20℃ / min; And / or, the holding time for the microwave heat treatment is 30~45 min.

3. The method for separating lithium and aluminum from lithium ore according to claim 1, characterized in that, The mass ratio of the lithium mica concentrate powder to the acid is 1:1.0~1.5; And / or, the temperature of the heated acid leaching is 70~85℃; And / or, the liquid-to-solid ratio of the heated acid leaching is 4-5 mL: 1 g; And / or, the heating and acid leaching time is 180~240 min; And / or, the stirring rate of the heated acid leaching is 300~400 rpm.

4. The method for separating lithium aluminum from lithium ore according to claim 1, characterized in that, The polar extraction system includes an extractant, a diluent, and a saponifying agent. The extractant is selected from di(2-ethylhexyl) phosphate (D2EHPA), the diluent is selected from sulfonated kerosene, and the saponifying agent is selected from sodium hydroxide (NaOH) solution. And / or, the saponification rate of the polar extraction system is 40-65%; And / or, the pH value of the polar extraction system is 7-8; And / or, the overall ratio O / A of the polar extraction system is 2.5~4.5:1; And / or, the mixing time for the extraction is 15-20 min; And / or, the clarification and separation time of the extraction is 20-30 min.

5. The method for separating lithium aluminum from lithium ore according to claim 1, characterized in that, Also includes: The aluminum-rich organic phase was back-extracted in a temperature-pH dual-response back-extraction system to obtain a high-purity aluminum-rich solution.

6. The method for separating lithium aluminum from lithium ore according to claim 5, characterized in that, The stripping agent used in the temperature-pH dual-response stripping system is a sulfuric acid solution; And / or, the temperature during the back-extraction process of the temperature-pH dual-response back-extraction system is 60~70℃; And / or, the aqueous phase obtained after back-extraction of the aluminum-rich organic phase in a temperature-pH dual-response back-extraction system has a pH value of 1, and the aqueous phase is the high-purity aluminum-rich solution. And / or, the ratio of O / A in the temperature-pH dual-response back-extraction system is 2:1; And / or, the mixing time for the back-extraction is 20-30 min; And / or, the separation time of the back-extraction is 20-30 min.

7. The method for separating lithium aluminum from lithium ore according to claim 1, characterized in that, Also includes: S4. Adsorbent is used to adsorb the lithium-rich aqueous phase to obtain a high-purity lithium-rich solution.

8. The method for separating lithium aluminum from lithium ore according to claim 7, characterized in that, The adsorbent is selected from a composite adsorbent of mesoporous alumina and graphene, and the specific surface area of ​​the composite adsorbent is >800 m². 2 / g, the adsorption capacity of the composite adsorbent is >120mg / g; And / or, the pH value of the lithium-rich aqueous phase is 6~6.5; And / or, the lithium-rich aqueous phase is adsorbed using a fixed-bed adsorption column filled with the adsorbent, wherein the flow rate of the lithium-rich aqueous phase is 2 to 3 BV / h during the adsorption process. And / or, after the adsorbent is saturated, it is eluted and regenerated using a dilute hydrochloric acid solution to achieve the recycling of the adsorbent.

9. The method for separating lithium aluminum from lithium ore according to claim 1, characterized in that, The material-to-ball ratio in the mixed ball mill is 15:1; And / or, the mixing ball milling is carried out in a planetary ball mill, and the planetary ball mill spindle speed of the planetary high-energy ball mill is 350~450 r / min; And / or, the mixing and ball milling time is 60~90 min.

10. The method for separating lithium aluminum from lithium ore according to claim 1, characterized in that, The chemical composition and mass percentage of the lepidolite concentrate powder are as follows: Li₂O 3.2 wt%, Al₂O₃ 32.65 wt%, SiO₂ 42.23 wt%, Fe₂O₃ 1.52 wt%, CaO 0.43 wt%, MgO 0.52 wt%, K₂O 6.22 wt%, Na₂O 2.68 wt%, TiO₂ 0.02 wt%, ZrO₂ <0.01 wt%, P₂O₅ 0.26 wt%, SO₃ <0.05 wt%, F 5.72 wt%, ZnO 0.02 wt%, SrO <0.01 wt%, MnO 0.25 wt%, NiO 0.03 wt%, CoO <0.01 wt%, CuO <0.01 wt%, Rb₂O 1.88 wt%, BaO <0.01 wt%, Cs₂O 0.18 wt%, the remainder being other impurities; And / or, the method is used to process the lepidolite concentrate powder such that the lithium leaching rate in the lepidolite concentrate powder is greater than 95%.

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