80 results about "Lithium sulfate" patented technology

The invention relates to a method for simultaneously preparing lithium hydroxide and sulfuric acid. The invention provides a method for simultaneously preparing lithium hydroxide and sulfuric acid, which comprises the following steps: preparing a bipolar membrane electrodialysis device which comprises a first bipolar membrane, an anion exchange membrane, a cation exchange membrane and a second bipolar membrane, and forming an acid chamber between the first bipolar membrane and the anion exchange membrane, a salt chamber is formed between the anion exchange membrane and the cation exchange membrane, and an alkali chamber is formed between the cation exchange membrane and the second bipolar membrane; a lithium sulfate aqueous solution is added into a salt chamber of the bipolar membrane electrodialysis device, a sulfuric acid aqueous solution is added into an acid chamber, and a lithium hydroxide aqueous solution is added into an alkali chamber; and discharging the desalted solution formed in the salt chamber of the bipolar membrane electrodialysis device, discharging the sulfuric acid aqueous solution formed in the acid chamber, and discharging the lithium hydroxide aqueous solution formed in the alkali chamber.

The invention relates to a method for efficiently extracting high-specification battery-grade lithium carbonate, and belongs to the technical field of lithium carbonate preparation. The method comprises the following steps: pretreatment: mixing a lithium-containing solution raw material with liquid caustic soda; extraction: fully mixing the lithium-containing solution with a no-load extraction agent, and performing phase splitting; reverse extraction: conveying sulfuric acid with a certain concentration and a lithium-containing load oil phase through a centrifugal pump respectively, fully mixing in an extraction tank, and splitting phases; calcium and magnesium are removed from the strip liquor, specifically, the strip liquor is adsorbed through resin, calcium and magnesium in the strip liquor are adsorbed and removed, and the resin is recycled through acid-base regeneration and water washing after adsorption saturation; wastewater treatment: firstly recycling an organic extracting agent in a non-dissolved state from the water-phase raffinate in the extraction procedure through an oil separator, and then treating and regenerating through a macroporous resin adsorption tank; precipitating lithium: placing the prepared sodium carbonate solution in a beaker, stirring and heating, slowly dropwise adding the lithium sulfate solution, continuously reacting, and filtering; and washing and drying: filtering, and drying the lithium carbonate obtained after filtering.

The invention discloses a method for recovering high-purity fluorine and silicon from fluorine-silicon slag and co-producing a low-alkali fluorine-free accelerator, which comprises the following steps: S1, dissolving the fluorine-silicon slag in a sodium hydroxide solution to obtain a solution A; s2, adding dilute sulphuric acid into the solution A, reacting until gel is obtained, and filtering to obtain filtrate A and high-purity silicon dioxide gel; s3, adding calcium sulfate and EDTA (Ethylene Diamine Tetraacetic Acid) into the filtrate A, stirring and reacting, and filtering after the reaction is finished to obtain calcium fluoride and filtrate B; and S4, taking clear water, heating, carrying out heat preservation, then adding aluminum sulfate, lithium sulfate, diethanol amine and the filtrate B obtained in S3, continuously stirring until the aluminum sulfate is completely dissolved, then adding hydrated magnesium silicate, continuously carrying out heat preservation stirring, and obtaining the low-alkali fluorine-free accelerator after stirring is finished. The method is simple in process and easy to implement industrially, and fluoride and silicon oxide obtained through separation are high in purity and beneficial to follow-up extension application; more importantly, high-value recycling of the fluorosilicon slag is achieved, and the problems of stockpiling waste and environmental pollution of the fluorosilicon slag are solved.

The invention provides a preparation method of battery-grade lithium salt, and relates to the technical field of new energy materials. Starting from battery-grade lithium sulfate, part of lithium sulfate is reduced under hydrogen to obtain battery-grade lithium sulfide; part of lithium sulfate reacts with sodium carbonate to obtain battery-grade lithium carbonate, the battery-grade lithium carbonate reacts with hydrochloric acid to obtain lithium chloride, lithium chloride is electrolyzed to obtain metal lithium, and the metal lithium reacts with sulfur, is reduced and is converted into battery-grade lithium sulfide; part of lithium sulfate reacts with sodium hydroxide to obtain battery-grade lithium hydroxide, and then the battery-grade lithium hydroxide reacts with hydrogenation tail gas to obtain battery-grade lithium sulfide. Further, the battery-grade lithium sulfide can be obtained from the lithium-containing ore through the steps of calcination, sulfuric acid leaching, purification and the like. Through conversion and adjustment among different lithium salts, the cost of the lithium sulfide can be adjusted according to different conditions, and low-cost and large-scale mass production of the lithium sulfide is realized.

The application discloses a purification and dissolution-resisting production method of battery-grade lithium carbonate, which comprises the following steps: 1) primary purification: cooling and cold precipitation of a crude lithium sulfate solution to obtain a primary purified solution; 2) secondary purification: adjusting the pH with sodium hydroxide, adding a flocculating agent, and filtering to obtain a secondary purified solution; 3) tertiary purification: adjusting the pH with sulfuric acid, sequentially adding disodium ethylenediaminetetraacetate, oxalic acid and activated carbon, and filtering to obtain a tertiary purified solution; 4) carbonization and synthesis: determining the content of Li in the tertiary purified solution, adding solid Na2CO3 or Na2CO3 solution according to the content of Li, and reacting for 30 min; adding dodecyl primary amine and reacting for 30 min, and filtering to obtain crude lithium carbonate; 5) washing: washing twice with water, washing with ethanol, filtering and drying to obtain battery-grade lithium carbonate; and 6) mother liquor recovery. The battery-grade lithium carbonate produced has a purity higher than 99.95%, a yield higher than 99%, and a whiteness higher than 95%, and realizes safe and environment-friendly production with high purity, high yield and high whiteness.

The application relates to the technical field of lithium hydroxide production, and discloses a processing technology for preparing battery-grade lithium hydroxide, which comprises the following steps: lithium ore is crushed to a reasonable particle size and then is sent into a roasting furnace, lithium ore is destroyed through high-temperature roasting, the roasted ore clinker is sent into a reaction kettle, sulfuric acid solution is added to carry out acidification reaction, then water is added to carry out leaching, and a crude leaching solution containing lithium sulfate is obtained. The application is provided with a sealing element, the large contact area design of the L-shaped sealing strip improves the reliability of the primary sealing, the cooperation of the elastic pressing strip and the spring can effectively compensate for the slight deformation in the equipment operation process, the stability of the sealing performance is ensured, the double-sealing structure can effectively prevent the leakage of the heat exchange medium, the problems of resource waste, environmental pollution and equipment damage caused by medium leakage are avoided, the influence of cross contamination of different media on product quality is also avoided.

The invention discloses a method for extracting lithium sulfate from high-iron spodumene concentrate, which comprises the following steps: mixing high-iron spodumene concentrate, sulfate and carbonate, and processing to obtain powder; the mass ratio of the high-iron spodumene concentrate to the sulfate to the carbonate is 1: (0.3-0.8): (0.01-0.5); the powder is subjected to brick pressing forming, a powder green brick is obtained, and the powder green brick is dried and roasted at the temperature of 900-1050 DEG C; cooling and crushing the roasted powder green brick to obtain a roasted particle material; adding water into the roasted particle material, carrying out ball milling, and leaching to obtain a leaching solution and leaching residues; and carrying out purification and concentration treatment on the leachate to obtain the lithium sulfate. By implementing the method, the interference of iron impurities can be eliminated, and the cost is reduced while the lithium recovery rate is improved.

The invention discloses a lithium salt crystallization method, which adopts a lithium precipitation kettle with two layers of ultrasonic generators arranged at diagonal positions in a kettle body, and comprises the following steps: starting the ultrasonic generators, and adjusting the ultrasonic frequency to be 20-150KHz; adding sodium carbonate and a lithium sulfate solution into the lithium precipitation kettle by adopting an inverse addition method; continuously carrying out ultrasonic reaction for 2-4 hours, and turning off the ultrasonic generator; and carrying out solid-liquid separation to obtain lithium carbonate. According to the invention, the scaling phenomenon in the reaction kettle can be basically eliminated completely, and scale blocks do not need to be cleaned manually; the content of impurities in the lithium salt is reduced: the content of sulfate radicals is reduced to 0.07% or below from 0.08% in the prior art and can be reduced to 0.045%, and the content of sodium ions is reduced to 0.02% or below from 0.025% in the prior art and can be reduced to 0.01% or below; and the particle size of the lithium salt crystal particles is reduced from the average particle size of 25-40 microns in the existing process to 3-20 microns in the process disclosed by the invention, and the appearance of the particles is more uniform.

The utility model discloses a lithium carbonate production wet process section lithium recovery device which is characterized in that a lithium precipitation mother liquor pipe is connected with a circulating pipe of an MVR crystallizer, a salt leg outlet of the MVR crystallizer is connected with an MVR thickening tank, a bottom outlet of the MVR thickening tank is connected with an inlet of an MVR centrifugal machine, and a solid phase outlet of the MVR centrifugal machine is connected with an inlet of a salt leaching tank; a liquid phase outlet of the MVR centrifugal machine is connected with an MVR mother liquor tank, an outlet of the MVR mother liquor tank is connected with a reflux inlet of the MVR crystallizer and a feed inlet of the freezing crystallizer, a bottom outlet of the freezing crystallizer is connected with an inlet of the freezing thickening tank, and a bottom outlet of the freezing thickening tank is connected with an inlet of the freezing centrifugal machine; a liquid phase outlet of the freezing centrifugal machine is connected with a freezing mother liquor tank; a bottom outlet of the freezing mother liquor tank is connected with a circulating pipe of the freezing crystallizer and a lithium sulfate discharging pipe. The device can improve the lithium recycling rate, the sodium sulfate quality and the product stability, and reduce the energy consumption and the labor cost.

The present disclosure relates to a method for preparing a lithium compound, which comprises: preparing lithium phosphate; mixing the lithium phosphate and sulfuric acid to obtain a mixture; converting the lithium phosphate into lithium sulfate through a reaction in the mixture; and separating the lithium sulfate into a solid phase. In the step of converting the lithium phosphate into lithium sulfate through a reaction in the mixture, the total concentration ([P+S] mol / L) of phosphorus (P) and sulfur (S) in the liquid phase of the mixture is 5 mol / L or more.

The present invention relates to a bipolar electrodialysis apparatus for producing lithium hydroxide and sulfuric acid from a lithium sulfate solution. A bipolar electrodialysis apparatus (100) for producing lithium hydroxide and sulfuric acid from lithium sulfate comprises: a positive electrode (20) and a negative electrode (30) that face each other; a first bipolar film (40), an anion-selective dialysis film (60), a cation-selective dialysis film (70), and a second bipolar film (50) that are disposed between the positive electrode (20) and the negative electrode (30); and a porous first nickel foam (80) disposed on the plane of the positive electrode (20) to be in close contact with each other and a porous second nickel foam (90) disposed on the plane of the negative electrode (30) to be in close contact with each other, wherein the nickel foams (80, 90) have a porosity of 50-90%.

The invention provides an impurity removal method for lithium sulfate slurry, and relates to the technical field of lithium salt purification. The impurity removal method comprises the following steps: mixing lithium sulfate slurry with calcium carbonate to form first to-be-reacted slurry; after the first to-be-reacted slurry is subjected to first precipitation, a first mixture is obtained; performing first solid-liquid separation on the first mixture to obtain a first filtrate and a first precipitate; mixing the first filtrate with a pH regulator, and carrying out second precipitation to obtain a second mixture; performing second solid-liquid separation on the second mixture to obtain a second filtrate and a second precipitate; wherein the pH value of the second mixture is 6-10; mixing the second filtrate, a sodium hydroxide solution and sodium carbonate to form third to-be-reacted slurry; performing third precipitation on the third to-be-reacted slurry to obtain a third mixture; and carrying out third solid-liquid separation on the third mixture to obtain a lithium sulfate refined solution and a third precipitate. According to the method, the zinc impurity in the lithium sulfate slurry can be effectively removed, and the purity of the lithium sulfate product is improved.

The invention discloses a biomass-based flexible hydrogel electrolyte adapting to an extreme environment and a preparation method and application thereof. The biomass-based flexible hydrogel electrolyte comprises gelatin, a lithium salt, LiOH.H2O, sodium lignin sulfonate and polyethylene glycol diglycidyl ether. The lithium salt comprises one of lithium bromide and lithium sulfate. The hydrogel electrolyte provided by the invention is low in cost and low in toxicity, has a self-healing function, has super-soft modulus (8.5 kPa) and high elongation at break (1558%), and can recover to the elongation of 1030% after being fractured and instantly self-healed; meanwhile, good adhesion is achieved, and the stability of an electrolyte-electrode interface can be kept for a long time; in addition, the ionic conductivity of the hydrogel electrolyte at-50 DEG C is up to 1.26 mS / cm; the supercapacitor assembled by using the hydrogel electrolyte has high energy density and excellent electrochemical performance in large-angle bending, fracture healing, extremely low temperature and high-temperature dry environments.

Processes for the recovery or purification of lithium species from various sources are described. Such sources include natural sources or deposits, such as in mining applications, and synthetic or non-natural sources, such as in the recycling of lithium species from batteries. In embodiments, the process comprises treating a Li2SO4-comprising aqueous solution with one or more barium salts to form a precipitate comprising barium sulfate (BaSO4). In embodiments, the processes may further comprise the preparation of a lithium sulfate-containing solution via treatment of the starting material or mixture with sulfuric acid. In embodiments, further treatments may be performed, for example prior to and / or subsequent to treatment with one or more barium salts, for example for initial or further sulfate removal, and / or removal of other metal species that may be present. The recovered lithium species be used directly, or converted into other forms, for use in a variety of applications.

The present disclosure relates to a method for recovering lithium from retired lithium-ion batteries. The method includes the following steps: mixing a reducing agent into the powder of retired ternary lithium-ion batteries for reduction to obtain reduced battery powder; initial acid leaching: adding a part of the reduced battery powder into sulfuric acid, and filtering to obtain a first-stage leaching solution and a first-stage leaching residue; cyclic acid leaching: replacing the sulfuric acid used in the initial acid leaching with the second-stage leaching solution to leach new reduced battery powder, obtaining a lithium sulfate solution and a cyclic first-stage residue. Flowing the lithium sulfate solution into a calcium and magnesium removal resin, and then electrolyzing to obtain a lithium hydroxide solution; then passing through a nanofiltration membrane system for nanofiltration, and finally evaporating and crystallizing the nanofiltrate to obtain battery-grade lithium hydroxide.

The application discloses a lithium extraction method and equipment, and aims at solving the technical problems of long process and serious environmental pollution in the sulfuric acid method. The method comprises the following steps: through mixing a first material with a sulfate ion-based acidifying agent to perform a sulfation reaction, the first material is converted into a second material containing lithium sulfate, the first material contains a lithium-based compound, and the lithium sulfate is obtained from the lithium-based compound through the sulfation reaction; after or at the same time of converting the first material into the second material containing lithium sulfate by mixing the first material with the sulfate ion-based acidifying agent to perform the sulfation reaction, the second material is calcined to fully perform the sulfation reaction and remove the sulfate ion-based acidifying agent which is not completely reacted; the lithium sulfate in the second material is gasified and volatilized from the second solid phase material by heating the second material, and the solid phase material remaining after the lithium sulfate in the second material is gasified and volatilized is a third material.

The invention discloses a method for removing fluorine from a lithium salt solution, and particularly relates to the technical field of lithium salt solution impurity removal, and the method comprises the following steps: S1, adding sodium hydroxide or lithium hydroxide into lithium salt solutions such as lithium sulfate and lithium chloride to adjust the lithium salt solutions to be alkaline, so that the lithium hydroxide solution can be directly used; s2, adding calcium hydrogen phosphate into the alkaline lithium salt solution, stirring, and filtering to obtain a low-fluorine lithium salt solution; compared with the prior art, the calcium hydrophosphate is innovatively selected as the fluorine removal agent for the lithium salt solution, the fluorine-removed lithium salt solution is obtained by adding the calcium hydrophosphate into the alkaline lithium salt solution, controlling the reaction time and filtering, the fluorine content of the fluorine-removed lithium salt solution is lower than 5 mg / L, the fluorine ion removal effect is good, and corrosion of fluorine ions to equipment is avoided.

The invention provides a method for removing impurities from a lithium sulfate strip liquor, a lithium sulfate solution, a lithium-containing compound and application. The method comprises the following steps: firstly, mixing a lithium sulfate strip liquor, a first impurity removal agent and a second impurity removal agent to obtain a mixed solution; the pH value of the mixed solution is adjusted to be acidic for the first time, a first filtrate and a first filter residue are obtained after the first reaction, the first impurity removing agent comprises a vulcanizing agent, and the second impurity removing agent comprises a calcium removing agent; the pH value of the first filtrate is adjusted to be alkaline for the second time, and second filtrate and second filter residues are obtained after the second reaction; and further treating the second filtrate to obtain a purified lithium sulfate solution. According to the impurity removal method provided by the invention, the concentration of divalent cation impurities such as copper, iron, calcium and magnesium in the lithium sulfate strip liquor can be greatly reduced, so that the purified lithium sulfate solution can meet the process requirements of a bipolar membrane system for preparing a lithium-containing product, and the large-scale production of the high-purity and high-efficiency lithium-containing product is realized.

The present application discloses a method for the co-production of lithium and potassium in magnesium sulfate salt lakes, and relates to the technical field of potassium and lithium extraction from salt lakes. The method comprises the following steps: naturally evaporating the brine of the magnesium sulfate salt lake until it is saturated with potassium chloride, separating the solid salt, mixing the remaining brine with lithium extraction brine, naturally evaporating the brine, separating the solid salt, obtaining old brine, and subjecting the old brine to a lithium extraction process to obtain a lithium salt product and a lithium extraction tail brine A. The present application returns the lithium extraction brine, which is mainly composed of magnesium chloride and is produced during the lithium salt production process, to the salt field and mixes it with potassium chloride saturated brine, thereby changing the precipitation path of the potassium salt ore and skipping the precipitation stage of soft potassium magnesium sulfate. This increases the yield of potassium salt and carnallite salt, while preventing the lithium in the brine from precipitating as lithium sulfate ore in the carnallite salt pool, thereby increasing the lithium salt yield. The method is characterized by simple operation, high efficiency, and readily available raw materials, and has practical significance for increasing the yield of potassium and lithium in the process of salt lake resource development.

The invention discloses a method for extracting lithium sulfate from spodumene concentrate, which comprises the following steps: mixing spodumene concentrate and auxiliary materials, and processing to obtain powder; the auxiliary materials comprise a first auxiliary material and a second auxiliary material, the first auxiliary material is lithium-containing tail mud, and the second auxiliary material is sulfate and / or carbonate; the powder is subjected to brick pressing forming, a powder green brick is obtained, and the powder green brick is dried and roasted at the temperature of 900-1050 DEG C; the roasted powder green bricks are crushed, and roasted particle materials are obtained; adding water into the roasted particle material, carrying out ball milling, and leaching to obtain a leaching solution and leaching residues; and carrying out purification and concentration treatment on the leachate to obtain the lithium sulfate. By implementing the method, base plate-free direct roasting can be realized, and the cost is reduced while the lithium recovery rate is improved.

Provided is a method for purifying a lithium sulfate solution, comprising the steps of: leaching a lithium-containing ore with sulfuric acid to obtain a lithium sulfate solution mixed with a leach residue; adding an alkaline supplementary material to the lithium sulfate solution mixed with the leach residue to form a magnesium precipitate; and removing the magnesium precipitate and the leach residue by solid-liquid separation, wherein the step of forming the magnesium precipitate is performed at a pH higher than the isoelectric point of the magnesium precipitate and lower than the isoelectric point of the leach residue.

The utility model discloses a batching machine for preparing a lithium sulfate solution, which comprises a protective cylinder, a base arranged at the bottom end of the protective cylinder and a guide rod arranged at the upper end of a first motor, a tray arranged on the upper side of the guide rod, and a bearing seat mounted on the lower side of the tray; the top cover is arranged at the outer end of the batching barrel, and a guide pipe is arranged on the lower side of the top cover; and the connecting cylinder is arranged on the inner side of the top cover, the right end of the second motor is connected with a guide assembly, and a second guide block is installed on the lower side of the first guide block. According to the batching machine for preparing the lithium sulfate solution, the volume of an added sulfuric acid solution can be controlled by additionally arranging the measuring cylinder and the feeding opening, and compared with a traditional technology, the batching machine has the function of controlling the volume of a liquid raw material of the lithium sulfate solution; and solid raw materials in the preparation of the lithium sulfate solution can be conveniently guided.

The invention discloses a method for preparing small-particle high-purity lithium phosphate by recovering waste lithium iron phosphate battery powder through a sodium method, which comprises the following steps: pulping the waste lithium iron phosphate battery powder, adding sulfuric acid and an oxidizing agent, reacting, and filtering to obtain an impurity-containing lithium sulfate solution and ferrophosphorus slag; adding caustic soda liquid to adjust the pH value of the impurity-containing lithium sulfate solution, adding sodium phosphate, and filtering to obtain an impurity-removed solution; removing fluorine, calcium and magnesium from the impurity-removed liquid to obtain a lithium sulfate solution, and evaporating and concentrating to obtain a concentrated lithium sulfate solution; and finally, adding the concentrated lithium sulfate solution into the sodium phosphate solution within 0.5-1 hour, and reacting at 60-70 DEG C for 1-2 hours to prepare the lithium phosphate with the particle size of 1-2 microns. According to the recovery method, the high-purity lithium phosphate product can be recovered and prepared, and the recovery rate is high; meanwhile, lithium phosphate with small particle size (the particle size is mainly distributed between 1-2 microns) can be prepared based on the method.

The present invention relates to a method for preparing lithium hydroxide, which comprises the following steps: a step of roasting a lithium-containing raw material with sulfuric acid; a step of leaching the roasted lithium-containing raw material to obtain a leaching step of obtaining a lithium sulfate solution; a first purification step of purifying the leached solution to a pH value of 7.1 to 9.5; a second purification step of purifying the first purified solution to a pH value of 9 to 11; and a step of performing a second purification step of the purified solution through bipolar electrodialysis to obtain a lithium hydroxide aqueous solution.

The present invention relates to the technical field of aluminum electrolyte recycling and utilization, and discloses a method for reducing the lithium content in a lithium-rich electrolyte for aluminum electrolysis and recovering lithium. The method comprises: uniformly mixing the lithium-rich electrolyte for aluminum electrolysis with an additive and then calcining the mixture to obtain a calcined product A; leaching the calcined product A to obtain a lithium-containing leachate B and a filter residue C; washing and drying the filter residue C, and returning the filter residue C to the aluminum electrolysis cell to continue serving as an electrolyte; purifying the lithium-containing leachate B, removing impurities, and evaporating and concentrating it to obtain a lithium-rich solution; adding a lithium precipitator to the lithium-rich solution to obtain a lithium salt product D. The method provided by the present invention converts the insoluble lithium fluoride in the lithium-rich electrolyte for aluminum electrolysis into readily soluble lithium sulfate, thereby reducing the lithium content in the lithium-rich electrolyte for aluminum electrolysis and achieving the comprehensive utilization of the lithium and fluorine resources in the electrolyte. Furthermore, the present invention has the characteristics of high lithium recovery rate, simple operation, and environmental friendliness.

The present invention provides an optimized method for recovering high-purity lithium sulfate from a lithium-containing composite oxide deposited on an eroded surface of a waste sagger discarded. Therefore, when the method for producing high-purity lithium sulfate from a waste sagger of the present invention is used, it is expected not only to be able to produce high-purity lithium sulfate that can be used for manufacturing lithium secondary batteries by recycling a discarded waste sagger, but also to be able to recycle a positive electrode active material, iron oxide, alumina, silicate, and calcium carbonate obtained as by-products during the production process of the lithium sulfate.

A method of producing sodium hydroxide (NaOH) or lithium hydroxide (LiOH) and sulfuric acid (H2SO4) includes generating sodium sulfate (Na2SO4) or lithium sulfate (Li2SO4) from battery manufacture and recovery and converting the generated Na2SO4 or Li2SO4 to NaOH, LiOH and H2SO4 by an electrochemical salt decomposition process. The treatment step may be performed in a closed system such that the generated Na2SO4 or Li2SO4 may be used during the conversion process, and optionally a purification step. In particular, LiOH, NaOH, and Na2SO4 are recovered to a battery recovery or battery manufacturing process.

The utility model relates to the technical field of lithium slag recovery, and discloses a lithium slag resource recycling device which comprises a box body, a clear water injection port and a lithium slag injection port are arranged at the two ends of the top of the box body in a penetrating mode, a partition plate is installed in the box body, a grinding mechanism is movably arranged above the partition plate, and a discharge port is arranged in the middle of the partition plate in a penetrating mode. A first valve is installed on the discharge port, a stirring mechanism is arranged in the box body and located below the discharge port, a concentrated sulfuric acid injection pipe is arranged on the side face of the box body in a penetrating mode, and a discharge port of the concentrated sulfuric acid injection pipe is located below the partition plate. By arranging the grinding mechanism, lithium slag and clear water can be ground together, so that slurry containing the lithium slag is obtained, smashing of the lithium slag is achieved, the stirring mechanism is arranged in the box body, fed concentrated sulfuric acid and the slurry containing the lithium slag can be fully mixed and react, and therefore a lithium sulfate solution and leaching slag can be conveniently obtained; the lithium slag is recycled and reused, and waste of resources is prevented.

The present invention provides a method for recovering lithium from a lithium precipitate mother liquor and battery-grade lithium carbonate. The method for recovering lithium from a lithium precipitate mother liquor of the present invention comprises first adding a composite extractant to the lithium precipitate mother liquor for extraction to obtain a loaded organic phase and a sodium sulfate raffinate; then adding acid to the loaded organic phase for back extraction to obtain a lithium sulfate solution; finally, adding sodium carbonate to the lithium sulfate solution to precipitate lithium, and filtering to obtain lithium carbonate and a filtrate; wherein the composite extractant is a mixture of HBL121 and a betaine-type amphoteric surfactant. The method for recovering lithium from a lithium precipitate mother liquor of the present invention significantly shortens the lithium extraction process, reduces costs, and can achieve a lithium yield of over 99.5%, significantly improving the lithium yield. The present invention also provides battery-grade lithium carbonate obtained by the method of the present invention.