Method for extracting lithium from lithium-containing electrolyte by leaching
By adopting lithium-containing electrolyte leaching and extraction methods in the electrolytic aluminum industry, including crushing, mixed salt roasting, acid leaching and fluorine removal, the problem of difficult slag material after lithium extraction is solved, and high efficiency and low cost are achieved Lithium extraction and high-quality lithium-containing solution production.
Patent Information
- Application Number
- CN202411638527.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-17
- Publication Date
- 2025-02-18
- Estimated Expiration
- Not applicable · inactive patent
AI Technical Summary
The waste electrolyte in the electrolytic aluminum industry is difficult to utilize after lithium extraction, and becomes hazardous waste, and it is easy to produce environmentally harmful substances during lithium extraction.
The lithium-containing electrolyte leaching method is adopted to remove cyanide by crushing and mixed salt roasting, and two acid leaching and fluorine removal treatments are carried out to obtain a lithium-containing solution.
It realizes efficient lithium extraction, reduces process costs, improves lithium leaching rate, and reduces solution impurities, and produces high quality lithium-containing solutions.
Smart Images
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Abstract
Description
Technical Field
[0001] The present application relates to the technical field of lithium extraction from waste aluminum electrolysis residues, and in particular to a method for extracting lithium by leaching lithium-containing electrolytes. Background Art
[0002] Lithium is an important strategic resource. As one of the important raw materials for power batteries, energy storage, and consumer batteries, it has important economic value and strategic significance. With the gradual reduction of mineral resources in recent years and cost constraints, lithium recycling technology has gradually gained attention. In the aluminum electrolysis production process, since aluminum ore resources originally contain a portion of lithium, and a certain amount of lithium fluoride needs to be added as an electrolysis aid in the electrolytic production of aluminum, there is about 1%-3% lithium in the aluminum electrolyte, which has a certain recycling value.
[0003] The main methods for extracting lithium from waste lithium-containing electrolytes from electrolytic aluminum include atmospheric pressure acid leaching, atmospheric pressure alkaline leaching, mixed salt roasting, and electrolysis + electrodeposition lithium extraction technology. However, due to the presence of a large amount of cyanide and fluoride in electrolytic aluminum waste, a large amount of environmentally harmful substances are easily produced during the lithium extraction process. Summary of the invention
[0004] The present application aims to provide a method for leaching lithium from a lithium-containing electrolyte, so as to solve the problem that the slag from the waste electrolyte in the existing aluminum electrolysis industry after lithium extraction is difficult to utilize and becomes hazardous waste.
[0005] In a first aspect, an embodiment of the present application provides a method for leaching lithium from a lithium-containing electrolyte, the method comprising:
[0006] crushing the lithium-containing electrolyte, and mixing the crushed lithium-containing electrolyte with a mixed salt in a preset ratio to form a mixture; the mixed salt includes one or more of calcium oxide, calcium hydroxide, aluminum hydroxide, calcium sulfate, aluminum sulfate, and magnesium sulfate;
[0007] Roasting the mixed material to remove cyanide in the mixed material to obtain a transformation material;
[0008] crushing the transformation material to obtain a powder material;
[0009] The powder material is subjected to a primary acid leaching with concentrated sulfuric acid and separated to obtain a primary leachate and a primary filter residue; the primary filter residue is subjected to a secondary acid leaching with concentrated sulfuric acid and separated to obtain a secondary leachate and a secondary filter residue;
[0010] The primary leaching solution and the secondary leaching solution are mixed evenly and subjected to a defluorination treatment to obtain a clean solution;
[0011] Adding water and oxalic acid to the secondary filter residue for pickling, and separating to obtain pickling residue and pickling liquid;
[0012] Adding oxalic acid and pickling solution to the clean liquid to separate and obtain a lithium-containing solution;
[0013] Sodium carbonate is added to the lithium-containing solution, and the pH is adjusted to 9-10, and the lithium carbonate is collected by filtration.
[0014] According to the first aspect, in a possible implementation, in the steps of subjecting the powder material to a primary acid leaching with concentrated sulfuric acid and separating to obtain a primary leachate and a primary filter residue; subjecting the primary filter residue to a secondary acid leaching with concentrated sulfuric acid and separating to obtain a secondary leachate and a secondary filter residue, the mass ratio of the concentrated sulfuric acid of the primary acid leaching and the secondary acid leaching to the powder material is (0.5-0.6):1.
[0015] According to the first aspect, in a possible implementation, the steps of subjecting the powder material to a primary acid leaching with concentrated sulfuric acid and separating to obtain a primary leachate and a primary filter residue; and subjecting the primary filter residue to a secondary acid leaching with concentrated sulfuric acid and separating to obtain a secondary leachate and a secondary filter residue include:
[0016] The powder material, concentrated sulfuric acid and water are mixed in a mass ratio of 1: (0.4-0.45): 1.5 and placed in a stirring device. The leaching temperature is 60° C.-95° C., the leaching time is 1 h-3 h, and after the leaching is completed, solid-liquid separation is performed to obtain a primary leachate and a primary filter residue;
[0017] The primary filter residue and water are mixed at a ratio of 1:1.5, concentrated sulfuric acid is added and placed in a stirring device, the leaching temperature is 60°C-95°C, the leaching time is 0.5h-3h, and after the leaching is completed, solid-liquid separation is performed to obtain a secondary filter residue and a secondary leachate.
[0018] According to the first aspect, in a possible implementation, the step of uniformly mixing the primary leachate and the secondary leachate and performing a defluorination treatment to obtain a clean liquid includes:
[0019] Mixing the primary leachate and the secondary leachate to form a mixed leachate;
[0020] Adding a flocculant to the mixed leachate, and adding CaO and / or Ca(OH)2 at a fluorine-calcium ratio of 0.6-0.8 according to the amount of F-substance in the primary leachate and the secondary leachate, until the pH reaches 4-6.5 to form a precipitate;
[0021] After filtering the precipitate, excess CaO and / or Ca(OH)2 is added to the solution until the pH of the solution is 8-14 to form a precipitate;
[0022] The precipitate was filtered again to obtain a clean liquid.
[0023] According to the first aspect, in a possible implementation manner, the flocculant includes one or more of Al(OH)3, PAC, AlCl3 and PAM, and the concentration of the flocculant is 0.8 g / L-1.5 g / L.
[0024] According to the first aspect, in a possible implementation, in the steps of adding water and oxalic acid to the secondary filter residue for pickling, separating to obtain the pickled residue and the pickling liquid, and in the step of adding oxalic acid and the pickling liquid to the first clean liquid, separating to obtain the lithium-containing solution, the total amount of oxalic acid added is equal to the amount of Ca in the secondary filter residue. 2+ Mg 2+ and Al 3+ The mass ratio of the substances is 1.5:1.
[0025] According to the first aspect, in a possible implementation, in the step of crushing the lithium-containing electrolyte and mixing the crushed lithium-containing electrolyte with a mixed salt in a preset ratio to form a mixture, the mixing ratio of the crushed lithium-containing electrolyte and the mixed salt is (3-6):1.
[0026] According to the first aspect, in a possible implementation, in the process of roasting the mixture to remove cyanide in the mixture, the roasting temperature is 200° C.-800° C., and the roasting holding time is 0.5 h-1 h.
[0027] According to the first aspect, in a possible implementation, the step of crushing the transformation material to obtain a powder material includes:
[0028] The transformation material is ground by a vibration mill and sieved through 100-200 meshes to obtain a powder material.
[0029] The lithium-containing electrolyte leaching and lithium extraction method provided in the present application uses a small amount of total sulfuric acid for two acid leachings, and the calcium oxide, calcium hydroxide, oxalic acid, etc. used are low in price. The entire process flow uses a relatively low cost to obtain a higher lithium leaching rate and very few solution impurities, and the produced lithium-containing solution is of high quality. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] In order to more clearly illustrate the implementation methods of the present application or the technical solutions in the prior art, the drawings required for use in the implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some implementation methods of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0031] Figure 1 The present invention is a schematic flow chart of a method for extracting lithium by leaching lithium from a lithium-containing electrolyte according to an embodiment;
[0032] Figure 2 The present invention is a process flow chart of a method for leaching lithium from a lithium-containing electrolyte according to an embodiment;
[0033] Figure 3 This is a detailed flowchart of step S50 in an embodiment. DETAILED DESCRIPTION
[0034] The words "preferably", "more preferably", etc. in the present invention refer to embodiments of the present invention that may provide certain beneficial effects in certain circumstances. However, other embodiments may also be preferred under the same circumstances or other circumstances. In addition, the description of one or more preferred embodiments does not imply that other embodiments are not applicable, nor is it intended to exclude other embodiments from the scope of the present invention.
[0035] When a numerical range is disclosed herein, the above range is considered to be continuous and includes the minimum and maximum values of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values of the range is included. In addition, when multiple ranges are provided to describe features or characteristics, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein should be understood to include any and all subranges included therein.
[0036] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, ordinary technicians in this field will not make any creative efforts.
[0037] Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.
[0038] The present application provides a method for leaching lithium from a lithium-containing electrolyte, such as Figure 1 and Figure 2 As shown, the method comprises the following steps:
[0039] Step S10, crushing the lithium-containing electrolyte, and mixing the crushed lithium-containing electrolyte with a mixed salt in a preset ratio to form a mixture; the mixed salt includes one or more of calcium oxide, calcium hydroxide, aluminum hydroxide, calcium sulfate, aluminum sulfate, and magnesium sulfate;
[0040] The crushing operation can increase the surface area of the lithium-containing electrolyte, thereby improving its reaction efficiency with the subsequently added mixed salt. The lithium-containing electrolyte can be crushed to a suitable particle size using appropriate crushing equipment, such as a ball mill, a jaw crusher, etc. The crushed lithium-containing electrolyte can be screened into a particle size range that meets the requirements using a vibrating screen or other screening equipment.
[0041] In order to ensure that the particle size of the lithium-containing electrolyte is uniform after crushing, it is necessary to avoid particles that are too large or too small from affecting the mixing effect and subsequent reactions.
[0042] All other embodiments obtained by mixing the lithium-containing electrolyte with the mixed salt under the premise of containing labor are within the scope of the present invention. The lithium electrolyte and the mixed salt are evenly dispersed together to form a mixture to promote the subsequent reaction with the mixed salt. A mixer such as a stirrer, a rotary mixer, etc. is used to evenly mix the lithium-containing electrolyte and the mixed salt to ensure that the two are fully in contact and ready for the subsequent reaction.
[0043] Step S20, roasting the mixture to remove cyanide in the mixture to obtain a transformation material;
[0044] The temperature range is set at 200℃-800℃. The selection of this temperature range is based on a deep understanding of the thermal decomposition characteristics of cyanide and the thermal stability of the mixture. Within this temperature range, cyanide can be effectively decomposed and converted into harmless or low-toxic substances, thus ensuring the safety of subsequent treatment.
[0045] The holding time is set to 0.5h-1h. The length of the holding time is affected by the roasting temperature, the composition of the mixture and the required removal efficiency. The appropriate holding time can ensure the complete decomposition of cyanide. At the same time, it can transform the Na2LiAlF6 crystals in the lithium-containing electrolyte raw materials and improve the lithium leaching efficiency.
[0046] The following reactions mainly occur during the roasting process:
[0047] 2Na3AlF6+3CaO=Al2O3+6NaF+3CaF2;
[0048] CaO + 2Al2O3 = CaO 2Al2O3;
[0049] 3CaO+2AlF3=Al2O3+3CaF2.
[0050] Use appropriate roasting equipment such as resistance furnace, muffle furnace, etc. for roasting. These equipment should have good temperature control and insulation performance to ensure that the roasting process can be carried out accurately at the set temperature and time.
[0051] Step S30, crushing the transformation material to obtain a powder material;
[0052] Add the transition material into the vibration mill and start the equipment for grinding. The vibration mill is a highly efficient crushing equipment that crushes the material into fine particles through vibration and friction.
[0053] The ground material needs to be screened by screening equipment, such as a vibrating screen. The screening equipment should choose a suitable screen size of 100-200 mesh to ensure that the particle size of the powder material is uniform and meets the requirements of subsequent processing.
[0054] The performance and parameters of the vibration mill (such as amplitude, frequency, grinding media, etc.) should be adjusted according to the properties of the material and the crushing requirements to obtain the best crushing effect.
[0055] Step S40, subjecting the powder material to a primary acid leaching with concentrated sulfuric acid and separating to obtain a primary leachate and a primary filter residue; subjecting the primary filter residue to a secondary acid leaching with concentrated sulfuric acid and separating to obtain a secondary leachate and a secondary filter residue;
[0056] In the primary acid leaching, the powder material, concentrated sulfuric acid and water are mixed in a mass ratio of 1:(0.4-0.45):1.5 and placed in a stirring device. The leaching temperature is 60°C-95°C, the leaching time is 1h-3h, and after the leaching is completed, solid-liquid separation is performed to obtain a primary leachate and a primary filter residue.
[0057] Since concentrated sulfuric acid is highly corrosive and oxidizing, it should be added slowly and carefully, and direct contact with skin or eyes should be avoided. Use a stirring device to stir thoroughly to ensure that the materials are mixed evenly to form a uniform acid leaching solution.
[0058] Set the leaching temperature to 60℃-95℃. This temperature range helps accelerate chemical reactions and improve acid leaching efficiency. At the same time, it is necessary to ensure that the temperature is controlled within a safe range to avoid excessive temperature causing equipment damage or chemical reactions to get out of control.
[0059] The leaching time is set to 1h-3h. The length of the leaching time depends on the nature of the material, the content of the target component and the required extraction efficiency. Within the set time, it should be ensured that the acid leaching reaction is fully carried out to maximize the extraction of the target component.
[0060] After leaching is completed, solid-liquid separation is performed using appropriate solid-liquid separation equipment, such as filters, centrifuges, etc. After separation, primary leachate and primary filter residue are obtained. The primary leachate contains the target component to be extracted and can be further processed or purified; the primary filter residue may contain incompletely reacted materials or other impurities, which can be subsequently processed as needed.
[0061] In the secondary acid leaching, the primary filter residue and water are mixed at a ratio of 1:1.5, concentrated sulfuric acid is added and placed in a stirring device, the leaching temperature is 60°C-95°C, the leaching time is 0.5h-3h, and after the leaching is completed, solid-liquid separation is performed to obtain secondary filter residue and secondary leachate.
[0062] Slowly add an appropriate amount of concentrated sulfuric acid to the mixed primary filter residue and aqueous solution. The amount of concentrated sulfuric acid added should be determined according to the content of the residual target component in the primary filter residue and the required extraction efficiency, but it should usually be kept within a certain ratio range to ensure the acid leaching effect.
[0063] Use a stirring device to fully stir the mixed materials to ensure that the concentrated sulfuric acid is evenly dispersed in the solution and fully contacts with the primary filter residue to promote the chemical reaction.
[0064] Set the leaching temperature to 60℃-95℃. This temperature range helps accelerate chemical reactions and improve acid leaching efficiency. As with the primary acid leaching, it is necessary to ensure that the temperature is controlled within a safe range to avoid excessive temperature causing equipment damage or chemical reactions to get out of control.
[0065] The leaching time is set to 0.5h-3h. The length of the leaching time depends on the content of the residual target component in the primary filter residue, the chemical reaction rate, and the required extraction efficiency. Within the set time, the acid leaching reaction should be fully carried out to maximize the extraction of the residual target component.
[0066] After leaching is completed, solid-liquid separation is performed using appropriate solid-liquid separation equipment, such as filters, centrifuges, etc., to obtain secondary leachate and secondary filter residue. The secondary leachate contains target components for further extraction and can be further processed or purified; the secondary filter residue may contain unreacted materials, impurities or other non-target components, which can be subsequently processed or disposed of as needed.
[0067] In the steps of subjecting the powder material to a primary acid leaching with concentrated sulfuric acid and separating to obtain a primary leachate and a primary filter residue; subjecting the primary filter residue to a secondary acid leaching with concentrated sulfuric acid and separating to obtain a secondary leachate and a secondary filter residue, the mass ratio of the total amount of concentrated sulfuric acid in the primary acid leaching and the secondary acid leaching to the powder material is (0.5-0.6):1. By reasonably controlling the amount of concentrated sulfuric acid used, it can be ensured that it fully reacts with the target components in the powder material, thereby improving the extraction efficiency. Avoiding excessive use of concentrated sulfuric acid can reduce production costs and improve overall economic benefits. Reducing the amount of concentrated sulfuric acid used helps to reduce the difficulty and cost of wastewater treatment, while reducing potential impacts on the environment.
[0068] Step S50, mixing the primary leachate and the secondary leachate evenly, and performing a defluorination treatment to obtain a clean liquid;
[0069] Specifically, Figure 3 As shown, step S50 includes:
[0070] Step S51, mixing the primary leachate and the secondary leachate to form a mixed leachate;
[0071] The primary leachate and the secondary leachate are mixed together to form a mixed leachate. The purpose of this step is to combine the target components extracted from the two acid leaching processes for subsequent defluorination treatment.
[0072] Step S52, adding a flocculant to the mixed leachate, and adding CaO and / or Ca(OH)2 at a fluorine-calcium ratio of 0.6-0.8 according to the amount of F-substance in the primary leachate and the secondary leachate, until the pH reaches 4-6.5 to form a precipitate;
[0073] Add an appropriate amount of flocculant to the mixed leachate. The selection of flocculant should be determined according to the composition and properties of the mixed leachate. Its function is to promote the aggregation and sedimentation of suspended particles in the solution, thereby improving the defluorination efficiency.
[0074] According to the amount of fluoride ion (F-) in the primary leachate and the secondary leachate, according to the fluoride-calcium ratio (F - / Ca 2+ CaO and / or Ca(OH)2 are added in a molar ratio of 0.6-0.8.
[0075] The pH of the mixed solution of the primary leaching solution and the secondary leaching solution is close to 1. CaO and / or Ca(OH)2 are added to adjust the pH value of the solution to 4-6.5. - Can be combined with Al in flocculant 3+ Complexation occurs with ion exchange and electrostatic adsorption, and then with Ca 2+ The purpose of this step is to make the fluoride ions react with the calcium ions to form a calcium fluoride (CaF2) precipitate, thereby removing the fluoride from the solution.
[0076] The generated calcium fluoride precipitate is filtered off to obtain a preliminary defluorinated solution.
[0077] The flocculant includes one or more of Al(OH)3, PAC, AlCl3 and PAM, and the concentration of the flocculant is 0.8g / L-1.5g / L.
[0078] Step S53, after filtering the precipitate, adding excess CaO and / or Ca(OH)2 to the solution until the pH of the solution is 8-14 to form a precipitate;
[0079] Add excess CaO and / or Ca(OH)2 to the preliminary defluorinated solution until the pH value of the solution reaches 8-14. The purpose of this step is to further remove the fluoride ions that may remain in the solution and to precipitate other impurity ions in the solution.
[0080] Step S54, filtering the precipitate again to obtain a clean liquid.
[0081] The generated precipitate is filtered out to obtain the final clean liquid, in which the fluoride ion content should be significantly reduced to meet the requirements of subsequent treatment or utilization.
[0082] Step S60, adding water and oxalic acid to the secondary filter residue for pickling, and separating to obtain pickled residue and pickling liquid;
[0083] Add appropriate amount of water and oxalic acid to the secondary filter residue for pickling operation.
[0084] During the pickling process, oxalic acid reacts with Ca in the secondary filter residue. 2 +, Mg2+ and Al3+ and other metal ions react to form corresponding oxalates.
[0085] After the reaction is completed, the pickling residue (unreacted solid residue) and the pickling liquid (solution containing oxalate) are separated by solid-liquid separation technology (such as filtration, centrifugation, etc.).
[0086] Step S70, adding oxalic acid and pickling solution to the clean liquid to separate and obtain a lithium-containing solution;
[0087] The clean solution obtained in step S50 is mixed with the pickling solution obtained in step S60. An appropriate amount of oxalic acid is added to the mixed solution, and the oxalic acid reacts with the lithium ions (if any) in the clean solution and the pickling solution and other possible metal ions to generate corresponding oxalates.
[0088] After the reaction is completed, the lithium-containing oxalate solution is separated from other components by appropriate separation techniques (such as precipitation, filtration, extraction, etc.) to obtain a lithium-containing solution.
[0089] In step S60 and step S70, the total amount of oxalic acid and the Ca 2 The mass ratio of Mg+, Mg2+ and Al3+ is set to 1.5: 1. This ratio is chosen to ensure that oxalic acid can fully react with metal ions while avoiding excessive use of oxalic acid, thereby improving resource utilization and reducing treatment costs.
[0090] Step S80, adding sodium carbonate to the lithium-containing solution, adjusting the pH to 9-10, and filtering to collect lithium carbonate.
[0091] The calcium oxide, calcium hydroxide, oxalic acid and the like used in the present invention are low in price, and the entire process flow uses a relatively low cost to obtain a higher lithium leaching rate and very few solution impurities, and the produced lithium-containing solution is of high quality.
[0092] Example 1: This example uses the waste electrolyte of a certain aluminum electrolytic enterprise in Shaanxi as raw material. The lithium content of the raw electrolyte is 2.93%. Its main components are as follows:
[0093] lithium% calcium% magnesium% iron% sodium% Potassium % aluminum% Sulfate % fluorine% Electrolytes 2.93 8.525 0.065 2.113 14.376 1.514 11.858 0.425 15.17
[0094] The raw materials are crushed by a crusher, sieved, and a mixed salt consisting of calcium hydroxide and aluminum sulfate in a certain proportion is added to the raw materials for calcination. The mixture is evenly mixed and placed in a muffle furnace for calcination at 500°C for 0.5h. The calcined electrolyte is fully ground and sieved to obtain 200g of 200-mesh fine material. Dilute sulfuric acid with a pH of 2 is added to the fine material, and it is placed in a stirring device for 90°C and stirred for 2h. After the reaction is complete, the solid-liquid separation is performed to obtain a primary leaching residue and a primary leaching liquid. A small amount of dilute sulfuric acid with a pH of 2 is added to the primary leaching residue, and it is placed in a stirring device for 90°C and stirred for 2h. After the reaction is complete, the solid-liquid separation is performed to obtain a secondary leaching residue and a secondary leaching liquid. After mixing an appropriate amount of PAC with Ca(OH)2, the flocculent is filtered out and the insoluble matter is filtered out, and then CaO is added to adjust the pH of the solution to >10 to purify the F in the solution. - 、SO4 2- The plasma filter removes the precipitate and collects the primary purification liquid. The secondary leaching residue is pickled with low-concentration oxalic acid three times, kept at 60℃ and stirred for 1h, and the pickling liquid is collected after solid-liquid separation. The primary purification liquid is subjected to secondary purification to remove Ca in the solution. 2+ Mg 2+ 、Al 3+ etc., add 10g oxalic acid and the pickling solution from the previous step to the solution, keep it at 60℃ and stir for 1h, filter out the solution after the reaction is complete, and the concentration and quality index of lithium in the solution are shown in the following table. The lithium leaching rate of this embodiment can reach 93.87%.
[0095] Lithium g / L Fluoride mg / L <![CDATA[SO4 2- g / L]]> <![CDATA[Ca 2+ mg / L]]> <![CDATA[Mg 2+ mg / L]]> One time leaching 10.336 229.672 27.414 488.623 2.877 secondary leaching 4.469 144.447 16.855 781.592 1.082 One-time purification 10.296 13.766 7.476 621.266 0.246 Pickling 0.818 7.943 3.151 0.818 0.183 Secondary purification 11.259 13.263 6.123 5.328 0.159
[0096] Example 2: The raw materials used in this example are the same as the electrolytes in Example 1, except that the mixed salt roasting material is different. The mixed salt roasting material is a mixture of calcium oxide and aluminum hydroxide in a certain proportion. The raw materials are crushed, sieved, mixed with the roasting material, and then placed in a muffle furnace for roasting and insulation at 500°C for 0.5h. The roasting material is ground in a vibrating mill and sieved to obtain 200-mesh fine materials. Concentrated sulfuric acid is mixed with water in a mass ratio of 0.3:1 to form dilute sulfuric acid. After mixing with the fine materials, it is placed in a stirring device and stirred at 90°C for 2h. After the reaction is complete, solid-liquid separation is performed to obtain a primary leaching residue and a primary leaching liquid. A small amount of dilute sulfuric acid with a pH of 2 is added to the primary leaching residue, and the mixture is placed in a stirring device and stirred at 90°C for 2h. After the reaction is complete, solid-liquid separation is performed to obtain a secondary leaching residue and a secondary leaching liquid. After mixing the two leaching solutions, add a certain proportion of Al(OH)3 and PAM coagulant and Ca(OH)2, filter out the insoluble matter, and then add excess CaO to adjust the solution pH to >10 to purify the F in the solution. - 、SO4 2-The plasma filter removes the precipitate and collects the primary purification liquid. The secondary leaching residue is pickled three times with low concentration oxalic acid, kept at 60℃ and stirred for 1h, and the solid-liquid separation is collected to collect the pickling liquid. The primary purification liquid is subjected to secondary purification to remove Ca in the solution. 2+ Mg 2+ 、Al 3+ etc., add 10g oxalic acid and the pickling solution in the previous step to the solution, keep warm at 60°C and stir for 1h, filter out the solution after the reaction is complete, the concentration and quality indicators of lithium in the solution are shown in the following table, and the lithium leaching rate of this embodiment can reach 95.23%.
[0097] Lithium g / L Fluoride mg / L <![CDATA[SO4 2- g / L]]> <![CDATA[Ca 2+ mg / L]]> <![CDATA[Mg 2+ mg / L]]> One time leaching 12.023 71.672 15.052 1000.36 6.165 secondary leaching 7.963 101.011 21.136 826.337 1.455 One-time purification 11.427 5.335 8.420 1564 0.07 Pickling 1.385 230 26.907 669.763 731 Secondary purification 12.605 4.694 9.817 48.204 1.23
[0098] Example 3: The raw materials used in this example are different from the above raw materials. The raw materials used in this example are cathode carbon blocks from a certain enterprise in Guangxi, and the lithium content of the cathode carbon blocks is 0.39. The raw materials are crushed and sieved, and the raw materials are fully mixed with calcium oxide and calcium hydroxide and then loaded into a crucible. The crucible is placed in a muffle furnace and roasted and kept warm for 0.5h at 500℃, and the loss on ignition is 8.3%. The roasted material is placed in a vibration mill and ground, and then sieved to obtain 200 mesh fine materials. Dilute sulfuric acid with a pH of 4 is added to the fine materials, and placed in a stirring device for 95℃ and stirred for 2h. After the reaction is complete, solid-liquid separation is performed to obtain a primary leaching residue and a primary leaching liquid. A small amount of dilute sulfuric acid is added to the primary leaching residue, and the mixture is placed in a stirring device for 90℃ and stirred for 2h. After the reaction is complete, solid-liquid separation is performed to obtain a secondary leaching residue and a secondary leaching liquid. After the two leaching liquids are mixed, Al(OH)3 and PAM coagulant and Ca(OH)2 are added, and the insoluble matter is filtered out, and then CaO is added to adjust the pH of the solution to >10 to purify the F in the solution. - 、SO4 2- The precipitate was filtered out by plasma and the primary purification liquid was collected. The secondary leaching residue was acid-washed three times with low concentration oxalic acid, kept at 60℃ and stirred for 1h, and then solid-liquid separation was performed to collect 45ml of acid washing liquid. The primary purification liquid was purified for the second time to remove Ca in the solution. 2+ Mg 2+ 、Al 3+ etc., add 10g oxalic acid and the pickling solution from the previous step to the solution, keep it at 60℃ and stir for 1h, filter out the solution after the reaction is complete, the concentration and quality index of lithium in the solution are shown in the following table. The lithium leaching rate of this embodiment can reach 92.01%.
[0099] Lithium g / L Fluoride mg / L <![CDATA[SO4 2- g / L]]> <![CDATA[Ca 2+ mg / L]]> <![CDATA[Mg 2+ mg / L]]> One time leaching 1.59 1020.63 151.90 1000.76 174.08 secondary leaching 1.16 800.02 162.18 864.23 237.36 One-time purification 1.86 10.52 9.62 954.97 0.11 Pickling 0.33 15.19 10.5 590.10 0.78 Secondary purification 1.03 9.52 10.05 8.49 0.48
[0100] The applicant declares that the present invention illustrates the detailed method of the present invention through the above-mentioned embodiments, but the present invention is not limited to the above-mentioned detailed method, that is, it does not mean that the present invention must rely on the above-mentioned detailed method to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the method of the present invention, addition of auxiliary steps, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A method for leaching lithium from a lithium-containing electrolyte, characterized in that: The method comprises: crushing the lithium-containing electrolyte, and mixing the crushed lithium-containing electrolyte with a mixed salt in a preset ratio to form a mixture; the mixed salt includes one or more of calcium oxide, calcium hydroxide, aluminum hydroxide, calcium sulfate, aluminum sulfate, and magnesium sulfate; Roasting the mixed material to remove cyanide in the mixed material to obtain a transformation material; crushing the transformation material to obtain a powder material; The powder material is subjected to a primary acid leaching with concentrated sulfuric acid and separated to obtain a primary leachate and a primary filter residue; the primary filter residue is subjected to a secondary acid leaching with concentrated sulfuric acid and separated to obtain a secondary leachate and a secondary filter residue; The primary leaching solution and the secondary leaching solution are mixed evenly and subjected to a defluorination treatment to obtain a clean solution; Adding water and oxalic acid to the secondary filter residue for pickling, and separating to obtain pickling residue and pickling liquid; Adding oxalic acid and pickling solution to the clean liquid to separate and obtain a lithium-containing solution; Sodium carbonate is added to the lithium-containing solution, and the pH is adjusted to 9-10, and the lithium carbonate is collected by filtration.
2. The method for leaching lithium from a lithium-containing electrolyte according to claim 1, characterized in that: In the steps of subjecting the powder material to a primary acid leaching with concentrated sulfuric acid and separating to obtain a primary leachate and a primary filter residue; subjecting the primary filter residue to a secondary acid leaching with concentrated sulfuric acid and separating to obtain a secondary leachate and a secondary filter residue, the mass ratio of the concentrated sulfuric acid in the primary acid leaching and the secondary acid leaching to the powder material is (0.5-0.6):
1.
3. The method for leaching lithium from a lithium-containing electrolyte according to claim 2, characterized in that: The steps of subjecting the powder material to a primary acid leaching with concentrated sulfuric acid and separating to obtain a primary leachate and a primary filter residue; and subjecting the primary filter residue to a secondary acid leaching with concentrated sulfuric acid and separating to obtain a secondary leachate and a secondary filter residue include: The powder material, concentrated sulfuric acid and water are mixed in a mass ratio of 1: (0.4-0.45): 1.5 and placed in a stirring device. The leaching temperature is 60° C.-95° C., the leaching time is 1 h-3 h, and after the leaching is completed, solid-liquid separation is performed to obtain a primary leachate and a primary filter residue; The primary filter residue and water are mixed at a ratio of 1:1.5, concentrated sulfuric acid is added and placed in a stirring device, the leaching temperature is 60°C-95°C, the leaching time is 0.5h-3h, and after the leaching is completed, solid-liquid separation is performed to obtain a secondary filter residue and a secondary leachate.
4. The method for leaching lithium from a lithium-containing electrolyte according to claim 1, characterized in that: The step of uniformly mixing the primary leaching solution and the secondary leaching solution and performing a defluorination treatment to obtain a clean solution comprises: Mixing the primary leachate and the secondary leachate to form a mixed leachate; Adding a flocculant to the mixed leachate, and adding CaO and / or Ca(OH)2 at a fluorine-calcium ratio of 0.6-0.8 according to the amount of F-substance in the primary leachate and the secondary leachate, until the pH reaches 4-6.5 to form a precipitate; After filtering the precipitate, excess CaO and / or Ca(OH)2 is added to the solution until the pH of the solution is 8-14 to form a precipitate; The precipitate was filtered again to obtain a clean liquid.
5. The method for leaching lithium from a lithium-containing electrolyte according to claim 4, characterized in that: The flocculant includes one or more of Al(OH)3, PAC, AlCl3 and PAM, and the concentration of the flocculant is 0.8g / L-1.5g / L.
6. The method for leaching lithium from a lithium-containing electrolyte according to claim 1, characterized in that: In the steps of adding water and oxalic acid to the secondary filter residue for pickling, separating to obtain the pickled residue and the pickling solution, and in the step of adding oxalic acid and the pickling solution to the first clean solution, separating to obtain the lithium-containing solution, the total amount of oxalic acid added is equal to the amount of Ca in the secondary filter residue. 2+ Mg 2+ and Al 3+ The mass ratio of the substances is 1.5:
1.
7. The method for leaching lithium from a lithium-containing electrolyte according to claim 1, characterized in that: In the step of crushing the lithium-containing electrolyte and mixing the crushed lithium-containing electrolyte with a mixed salt in a preset ratio to form a mixture, the mixing ratio of the crushed lithium-containing electrolyte and the mixed salt is (3-6):
1.
8. The method for leaching lithium from a lithium-containing electrolyte according to claim 1, characterized in that: In the process of roasting the mixed material to remove the cyanide in the mixed material, the roasting temperature is 200° C.-800° C., and the roasting holding time is 0.5 h-1 h.
9. The method for leaching lithium from a lithium-containing electrolyte according to claim 1, characterized in that: The step of crushing the transformation material to obtain a powder material comprises: The transformation material is ground by a vibration mill and sieved through 100-200 meshes to obtain a powder material.