Method for extracting lithium from solid waste of aluminum electrolysis cell

Abstract

The invention provides a method for extracting lithium from solid waste of an aluminum electrolysis cell, and relates to the technical field of extraction of lithium from solid waste, the method for extracting lithium from the solid waste of the aluminum electrolysis cell comprises the following steps: S1, raw material pretreatment; s2, performing primary roasting to remove carbon and break cyanogen; s3, carrying out secondary fluorine-fixing roasting; step S4, water leaching and phase separation; s5, impurity removal of the first immersion liquid; step S6, extracting lithium phosphate; and step S7, synthesizing lithium dihydrogen phosphate. The invention discloses a method for extracting lithium from aluminum electrolysis cell solid waste. Directional lithium dissociation of the solid waste of the aluminum electrolysis cell is achieved, carbon wrapping is broken through first-stage roasting, and lithium activity is released; through secondary calcium sulfate fluorine fixation, lithium is prevented from being wrapped by calcium salt, and compared with a traditional CaO method, the lithium leaching rate is effectively increased; fine control of products in the process is realized; free acid is controlled to be less than or equal to 0.1% through a lithium dihydrogen phosphate crystallization process; and the F / Al ratio is regulated and controlled to adapt to different batteries through the acid dissolution condition of the aluminum hydroxyfluoride.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction technology from solid waste, and in particular to a method for extracting lithium from solid waste using an aluminum electrolysis cell. Background Technology

[0002] Overhaul slag from aluminum electrolytic cells is a hazardous waste (HW48 category) generated during the replacement of old linings in the process of aluminum electrolysis production, with an annual discharge exceeding 2 million tons / year. Its core problems are: high toxicity: containing soluble fluorides (8-20%) and cyanides (0.1-0.8%), with leached fluoride concentrations exceeding the national standard (GB 5085.3) by more than 100 times; resource waste: rich in lithium (0.2-1.8%), aluminum (10-35%), and residual carbon (30-50%), especially with lithium content equivalent to low-grade lithium ore (such as lepidolite containing 1.2-3.5% Li2O).

[0003] The composition of solid waste slag from aluminum electrolytic cells is complex, with charcoal blocks, refractory materials, and fluoride salts coexisting. Traditional technologies struggle to achieve full-scale resource utilization, and further research is needed to effectively improve the recovery and extraction rate of lithium resources from solid waste slag from aluminum electrolytic cells.

[0004] Therefore, it is necessary to provide a method for extracting lithium from solid waste in aluminum electrolysis cells to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides a method for extracting lithium from solid waste from aluminum electrolysis cells, addressing the need for further research on how to effectively improve the recovery and extraction rate of lithium resources from the overhaul residue of aluminum electrolysis cells.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for extracting lithium from solid waste in aluminum electrolysis cells, comprising the following steps:

[0007] Step S1, raw material pretreatment, crushing and fine grinding the aluminum electrolytic cell overhaul slag to obtain grinding powder;

[0008] Step S2, primary roasting to remove carbon and cyanide: The powder material is placed in a tube furnace for primary roasting treatment to obtain primary roasting slag.

[0009] Step S3, secondary solid fluoride roasting: The primary roasting residue is mixed with calcium sulfate and placed in a muffle furnace for secondary roasting treatment to obtain secondary roasting residue;

[0010] Step S4, water leaching and phase separation: the secondary roasted residue is added to deionized water at a liquid-to-solid ratio of 3-8:1, stirred and treated, and then filtered to obtain a first leaching solution and a first leaching residue.

[0011] Step S5, one-time immersion to remove impurities:

[0012] Step S51: Add calcium oxide suspension to the first soaking solution, adjust the pH to 12.0±0.2, stir for 30 minutes, and filter to obtain the filtrate;

[0013] Step S52: Add sodium carbonate solution to the filtrate until no precipitate forms, then filter to obtain purified solution;

[0014] Step S6, lithium phosphate extraction: After heating the purified solution and stirring, trisodium phosphate solution is added dropwise to react. After filtration, the precipitate is washed with hot water to obtain lithium phosphate precipitate.

[0015] Step S7, Lithium dihydrogen phosphate synthesis: Lithium phosphate is mixed with concentrated phosphoric acid, stirred and reacted, then evaporated and crystallized, and dried to obtain lithium dihydrogen phosphate.

[0016] Preferably, in step S1, the crushing and grinding process involves coarse crushing to a particle size ≤5mm using a jaw crusher, followed by fine grinding to 80-200 mesh using a ball mill.

[0017] Preferably, in step S2, oxygen is introduced during the first-stage roasting, and the temperature is increased to 500-800°C at 5°C / min and held for 1-4 hours. This ensures that lithium fluoride is not significantly lost, promotes carbon removal, and achieves a cyanide decomposition rate of >99.8%.

[0018] Preferably, the concentration of oxygen is in the range of 20-100%.

[0019] Preferably, in step S3, calcium sulfate is added to the secondary roasting slag at a ratio of n(Ca):n(F) = 1.0-1.5.

[0020] Preferably, in step S3, the secondary calcination process involves heating the temperature at 3°C / min to 400-750°C and holding it at that temperature for 1-3 hours.

[0021] Preferably, in step S4, the stirring temperature is controlled at 60-90℃ and the stirring time is controlled at 1-2 hours.

[0022] Preferably, in step S52, the amount of sodium carbonate solution added is 1.05 times the molar amount of calcium.

[0023] Preferably, in step S6, the temperature is raised to 60-80℃, and a 0.5-1.0 mol / L trisodium phosphate solution is added dropwise while stirring at 300 rpm. The reaction is carried out for 1 hour, and the precipitate is washed with hot water 2-3 times after filtration.

[0024] Preferably, in step S7, lithium phosphate and concentrated phosphoric acid are mixed at a ratio of n(H3PO4):n(Li3PO4) = 3.05:1, the stirring temperature is 60°C, the stirring reaction time is 2 hours, and the drying temperature is 100°C.

[0025] Compared with related technologies, the method for extracting lithium from solid waste in aluminum electrolysis cells provided by this invention has the following advantages:

[0026] The method achieves directional lithium dissociation from solid waste in aluminum electrolysis cells. The first-stage roasting breaks down the carbon coating and releases lithium activity; the second-stage calcium sulfate fixation prevents lithium from being coated by calcium salts. Compared with the traditional CaO method, the lithium leaching rate is effectively improved.

[0027] The process achieves refined control of the product: the free acid content is controlled to ≤0.1% through the lithium dihydrogen phosphate crystallization process; the F / Al ratio (0.5-1.0) is adjusted to adapt to different batteries by adjusting the acid solubility conditions of aluminum hydroxyfluoride. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0029] Figure 1 A three-dimensional view of a first embodiment of the ball mill provided by the present invention;

[0030] Figure 2 for Figure 1 A sectional view of section AA shown;

[0031] Figure 3 for Figure 2 The schematic diagram of the cross-sectional structure of the ball mill cylinder shown is as follows: Figure 3 (a) in the middle is Figure 2 The sectional view of section BB shown. Figure 3 (b) in the middle is Figure 3 A magnified view of part (a) in the diagram;

[0032] Figure 4 for Figure 2 The diagram shows the structure of the transmission ring.

[0033] Figure 5 for Figure 2 A sectional view of the CC section shown;

[0034] Figure 6 for Figure 2 A schematic diagram of the cross-sectional structure of the cleaning mechanism shown.

[0035] Figure 7 This is a schematic diagram of the second embodiment of the ball mill provided by the present invention.

[0036] Explanation of icon numbers:

[0037] 1. Install the base;

[0038] 2. Feeding mechanism; 21. Feeding tube seat; 22. First driving component; 23. Screw conveyor rod;

[0039] 3. Discharge mechanism; 31. Discharge pipe seat; 32. Screw conveyor; 33. Filter baffle; 34. Connecting rod;

[0040] 4. Ball mill mechanism; 41. Ball mill cylinder; 410. Sliding hole; 411. Shrinkage groove; 42. First elastic element; 43. Movable plug; 44. Synchronous slide rod; 45. Transmission ring;

[0041] 5. Switching mechanism; 51. First telescopic component; 52. Switch plate;

[0042] 6. Drive mechanism; 61. Second drive component; 62. First synchronous pulley component;

[0043] 7. Feeding mechanism; 71. Feeding box; 72. Diverter plate; 73. Movable filter plate; 74. Third drive component; 75. Cam;

[0044] 8. Drainage mechanism; 81. Discharge pipe; 82. Conveyor belt assembly;

[0045] 9. Cleaning mechanism; 91. Rotating shaft; 92. Support; 93. Cleaning block; 94. Second elastic element;

[0046] 741. Synchronous shaft; 742. Second synchronous pulley.

[0047] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0049] This invention provides a method for extracting lithium from solid waste in aluminum electrolysis cells.

[0050] The method for extracting lithium from solid waste in aluminum electrolysis cells according to this invention includes the following steps:

[0051] Step S1, raw material pretreatment, crushing and fine grinding the aluminum electrolytic cell overhaul slag to obtain grinding powder;

[0052] Step S2, primary roasting to remove carbon and cyanide: The powder material is placed in a tube furnace for primary roasting treatment to obtain primary roasting slag.

[0053] Step S3, secondary solid fluoride roasting: The primary roasting residue is mixed with calcium sulfate and placed in a muffle furnace for secondary roasting treatment to obtain secondary roasting residue;

[0054] Step S4, water leaching and phase separation: the secondary roasted residue is added to deionized water at a liquid-to-solid ratio of 3-8:1, stirred and treated, and then filtered to obtain a first leaching solution and a first leaching residue.

[0055] Step S5, one-time immersion to remove impurities:

[0056] Step S51: Add calcium oxide suspension to the first soaking solution, adjust the pH to 12.0±0.2, stir for 30 minutes, and filter to obtain the filtrate;

[0057] Step S52: Add sodium carbonate solution to the filtrate until no precipitate forms, then filter to obtain purified solution;

[0058] Step S6, lithium phosphate extraction: After heating the purified solution and stirring, trisodium phosphate solution is added dropwise to react. After filtration, the precipitate is washed with hot water to obtain lithium phosphate precipitate.

[0059] Step S7, Lithium dihydrogen phosphate synthesis: Lithium phosphate is mixed with concentrated phosphoric acid, stirred and reacted, then evaporated and crystallized, and dried to obtain lithium dihydrogen phosphate.

[0060] In step S1, the crushing and fine grinding process involves coarse crushing to a particle size ≤5mm using a jaw crusher, followed by fine grinding to 80-200 mesh using a ball mill.

[0061] In step S2, oxygen or a nitrogen-oxygen mixture is introduced during the first-stage roasting process, and the temperature is increased to 500-800℃ at a rate of 5℃ / min and held for 1-4 hours. The lithium fluoride is basically not lost, which promotes the removal of carbon and the cyanide decomposition rate is >99.8%.

[0062] The oxygen concentration ranges from 20% to 100%.

[0063] In step S3, calcium sulfate is added to the secondary roasted slag according to the ratio of n(Ca):n(F) = 1.0-1.5.

[0064] In step S3, the secondary calcination process involves heating the temperature at 3°C / min to 400-750°C and holding it at that temperature for 1-3 hours.

[0065] In step S4, the stirring temperature is controlled at 60-90℃ and the stirring time is controlled at 1-2 hours.

[0066] In step S52, the amount of sodium carbonate solution added is 1.05 times the molar amount of calcium.

[0067] In step S6, the temperature is raised to 60-80℃, and 0.5-1.0 mol / L trisodium phosphate solution is added dropwise while stirring at 300 rpm. The reaction is carried out for 1 hour, and the precipitate is washed with hot water 2-3 times after filtration.

[0068] In step S7, lithium phosphate and concentrated phosphoric acid are mixed at a ratio of n(H3PO4):n(Li3PO4) = 3.05:1, the stirring temperature is 60℃, the stirring reaction time is 2 hours, and the drying temperature is 100℃.

[0069] It also includes the following steps:

[0070] Step S8: High-value utilization of leaching residue:

[0071] To prepare aluminum hydroxyfluoride, a leaching residue was mixed with 60-98 wt% sulfuric acid at a solid-liquid ratio of 1:5, reacted at 90°C for 3 hours, filtered and washed until neutral, and dried at 120°C.

[0072] Beneficial effects:

[0073] The method achieves directional lithium dissociation from solid waste in aluminum electrolysis cells. The first-stage roasting breaks down the carbon coating and releases lithium activity; the second-stage calcium sulfate fixation prevents lithium from being coated by calcium salts. Compared with the traditional CaO method, the lithium leaching rate is effectively improved.

[0074] The process achieves refined control of the product: the free acid content is controlled to ≤0.1% through the lithium dihydrogen phosphate crystallization process; the F / Al ratio (0.5-1.0) is adjusted to adapt to different batteries by adjusting the acid solubility conditions of aluminum hydroxyfluoride.

[0075] Implementation Plan 1:

[0076] Step 1: Raw material pretreatment:

[0077] 300g of aluminum electrolytic cell overhaul slag was coarsely crushed in a jaw crusher to make its particle size ≤5mm; then it was transferred to a ball mill and finely ground to 150 mesh to obtain uniform powder.

[0078] Step 2: Primary roasting to remove carbon and break down cyanide:

[0079] The powder was transferred to a tube furnace, and a mixture of oxygen and nitrogen (O2 concentration 60%) was introduced. The furnace was heated to 700°C at a heating rate of 5°C / min and held for 2 hours. At this point, the carbon residue was <3%, and the cyanide decomposition rate was >99.9%.

[0080] Step 3: Secondary solid fluorine roasting:

[0081] Calcium sulfate was added to the primary roasted slag at a ratio of n(Ca):n(F) = 1.2. The mixture was placed in a muffle furnace and heated to 600℃ at a rate of 3℃ / min, and held for 2 hours. At this point, the fluorine fixation rate was >99% and the crystallinity of CaF2 was >90%.

[0082] Step 4: Water immersion phase separation:

[0083] Add 1500 mL of deionized water to the secondary roasted residue at a liquid-to-solid ratio of 5:1, and stir at 80°C for 1.5 hours. After filtration, a lithium-rich primary leaching solution and a primary leaching residue containing CaF2, Al2O3, and SiO2 are obtained.

[0084] Step 5: One-stage immersion for impurity removal (two-stage purification):

[0085] Al / Fe removal: Add calcium oxide suspension to the first immersion solution, adjust the pH to 12.0±0.2, stir for 30 minutes, and then filter. The removal rates of Al and Fe are >99.5% and >99.8%, respectively.

[0086] Calcium removal: Add sodium carbonate solution to the filtrate until no precipitate forms. At this point, the calcium content is reduced. 2+ Concentration ≤10ppm.

[0087] Step 6: Lithium phosphate precipitation:

[0088] The purified solution was heated to 70°C and stirred at 300 rpm. A 0.5 mol / L trisodium phosphate solution was added dropwise, and the reaction was allowed to proceed for 1 hour. After filtration, the precipitate was washed twice with hot water to remove adsorbed impurity ions.

[0089] Step 7: Lithium dihydrogen phosphate synthesis:

[0090] The prepared lithium phosphate was mixed with concentrated phosphoric acid at a ratio of n(H3PO4):n(Li3PO4) = 3.05:1, and the mixture was stirred at 60°C for 2 hours. After evaporation and crystallization, the mixture was dried at 100°C to obtain lithium dihydrogen phosphate product that meets battery-grade standards.

[0091] Step 8: High-value utilization of leaching residue:

[0092] A residue from an leaching process was mixed with 60 wt% sulfuric acid at a solid-liquid ratio of 1:5 and reacted at 90°C for 3 hours. After filtration and washing until neutral, the mixture was dried at 120°C to prepare aluminum hydroxyfluoride.

[0093] Implementation Plan Two:

[0094] Step 1: Raw material pretreatment:

[0095] 500g of aluminum electrolytic cell overhaul slag is coarsely crushed to a particle size of ≤5mm using a jaw crusher, and then finely ground to 150 mesh using a ball mill.

[0096] Step 2: Primary roasting to remove carbon and break down cyanide:

[0097] The powder is placed in a tube furnace, pure oxygen is introduced, and the temperature is increased to 700°C at 5°C / min and held for 2 hours to achieve efficient carbon removal and cyanide removal.

[0098] Step 3: Secondary solid fluorine roasting:

[0099] Calcium sulfate was added at a ratio of n(Ca):n(F) = 1.2, and the mixture was heated to 600°C in a muffle furnace at a rate of 3°C / min and held for 2 hours.

[0100] Step 4: Water immersion phase separation:

[0101] Add 3000 mL of deionized water at a liquid-to-solid ratio of 6:1, stir at 80°C for 1.5 hours, and then filter.

[0102] Step 5: One-stage immersion for impurity removal (two-stage purification):

[0103] As in Implementation Scheme 1, Al, Fe and Ca impurity ions are removed sequentially.

[0104] Step 6: Lithium phosphate precipitation:

[0105] The purified solution was heated to 70°C, and 0.7 mol / L trisodium phosphate solution was added dropwise. After reacting for 1 hour, the solution was filtered and washed.

[0106] Step 7: Lithium dihydrogen phosphate synthesis:

[0107] Lithium phosphate and concentrated phosphoric acid were mixed and reacted at a ratio of n(H3PO4):n(Li3PO4) = 3.05:1, then evaporated to crystallize and dried.

[0108] Step 8: High-value utilization of leaching residue:

[0109] In the same manner as in Implementation Scheme 1, aluminum hydroxyfluoride was prepared.

[0110] Implementation Plan 3:

[0111] Step 1: Raw material pretreatment:

[0112] 1 kg of aluminum electrolytic cell overhaul slag was coarsely crushed using a jaw crusher and finely ground to 150 mesh using a ball mill. Step 2: Primary roasting for decarbonization and cyanide removal:

[0113] A mixture of oxygen and nitrogen (O2 concentration 60%) was introduced and heated to 700°C in a tube furnace at a rate of 5°C / min, and held at that temperature for 2 hours.

[0114] Step 3: Secondary solid fluorine roasting:

[0115] Calcium sulfate was added at a ratio of n(Ca):n(F) = 1.2, and the mixture was heated to 600°C in a muffle furnace at a rate of 3°C / min and held for 2 hours.

[0116] Step 4: Water immersion phase separation:

[0117] Add 7000 mL of deionized water at a liquid-to-solid ratio of 7:1, stir at 80°C for 1.5 hours, and then filter.

[0118] Step 5: One-stage immersion for impurity removal (two-stage purification):

[0119] The same as in Implementation Plan 1, the removal of impurity ions is completed.

[0120] Step 6: Lithium phosphate precipitation:

[0121] The purified solution was heated to 70°C, and a 1.0 mol / L trisodium phosphate solution was added dropwise. After reacting for 1 hour, the solution was filtered and washed.

[0122] Step 7: Lithium dihydrogen phosphate synthesis:

[0123] Lithium phosphate and concentrated phosphoric acid were mixed and reacted at a ratio of n(H3PO4):n(Li3PO4) = 3.05:1, then evaporated to crystallize and dried.

[0124] Step 8: High-value utilization of leaching residue:

[0125] In the same manner as in Implementation Scheme 1, aluminum hydroxyfluoride was prepared.

[0126] The three implementation schemes described above, using 300g, 500g, and 1kg of aluminum electrolysis cell solid waste as raw materials respectively, successfully produced lithium dihydrogen phosphate products that meet battery-grade standards through the same process steps, achieving high-value utilization of the leaching residue. Each embodiment strictly controlled process parameters to ensure high reaction efficiency and high product quality.

[0127] The present invention also provides a ball mill for raw material pretreatment in the method for extracting lithium from solid waste in aluminum electrolysis cells.

[0128] Please refer to the following: Figures 1 to 4 In this invention, the ball mill includes:

[0129] Mounting base 1;

[0130] The feeding mechanism 2 includes a feeding tube seat 21, a first driving member 22, and a spiral conveying rod 23. The bottom of the feeding tube seat 21 is fixedly mounted on the top of the mounting base 1. The first driving member 22 is fixedly mounted on the feeding tube seat 21. The driving part of the first driving member 22 passes through the feeding tube seat 21 and is fixedly connected to the spiral conveying rod 23. The feeding tube seat 21 is provided with a feeding port.

[0131] The discharge mechanism 3 includes a discharge pipe seat 31, a spiral conveyor cylinder 32, and a filter baffle 33. The bottom of the discharge pipe seat 31 is fixed to the top of the mounting base 1. The spiral conveyor cylinder 32 is rotatably installed inside the discharge pipe seat 31. The filter baffle 33 is fixed to the input end of the spiral conveyor cylinder 32.

[0132] The ball milling mechanism 4 includes a ball mill cylinder 41, a first elastic element 42, a movable plug 43, a synchronous slide rod 44, and two transmission rings 45. The ball mill cylinder 41 is rotatably mounted between the feed pipe seat 21 and the discharge pipe seat 31. The ball mill cylinder 41 has sliding holes 410 and shrinkage grooves 411, which are staggered and interconnected. The first elastic element 42 elastically connects the ball mill cylinder 41 and the movable plug. 43, the movable plug 43 is slidably connected through the shrinkage groove 411, the two transmission rings 45 are respectively fixed on the feed pipe seat 21 and the discharge pipe seat 31, the synchronous slide rod 44 passes through the range of the sliding hole 410, and the two ends of the synchronous slide rod 44 are respectively slidably installed on the surfaces of the two transmission rings 45, the inner side of the movable plug 43 abuts against the synchronous slide rod 44, and the connecting rod 34 is fixedly connected to the ball mill cylinder 41 and the spiral conveyor cylinder 32;

[0133] Switching mechanism 5, which is disposed on the ball mill cylinder 41;

[0134] Drive mechanism 6, which is mounted on the mounting base 1, is used to drive the ball mill cylinder 41 to rotate and adjust.

[0135] The sliding holes 410 are provided in at least eight ways; the shrinkage grooves 411 are provided in at least eight groups, and each group of shrinkage grooves 411 is provided with at least nine grooves.

[0136] In this embodiment, the area of ​​the ball mill cylinder 41 is filled with ball milling balls for ball milling the materials within the area of ​​the ball mill cylinder 41.

[0137] In this embodiment, the first driving component 22 adopts a motor drive structure to provide power for the rotation adjustment of the spiral conveying rod 23, so as to facilitate the spiral conveying of materials entering the range of the feed tube seat 21 to the range of the ball mill cylinder 41.

[0138] In this embodiment, the first elastic element 42 is a spring structure, which is used to maintain the elastic contact between the movable plug 43 and the synchronous slide rod 44, so that when the synchronous slide rod 44 extends or retracts relative to the ball mill cylinder 41, the movable plug 43 can maintain the contact relationship with the synchronous slide rod 44.

[0139] In this embodiment, as Figure 4 As shown, when the synchronous slide bar 44 is located within a 115° range to the left of the transmission ring 45, the synchronous slide bar 44 is in a retracted state;

[0140] When the synchronous slide bar 44 is located within a 217° range to the right of the transmission ring 45, the synchronous slide bar 44 is in an extended state.

[0141] This allows the synchronous slide rod 44 to adaptively switch between the extension and retraction states when it slides within the range of the transmission ring 45.

[0142] The inner wall of the ball mill cylinder 41 is provided with a shrinkage groove 411, which facilitates stable rotational conveying of the ball mill balls after installation and use, and raises the height of the ball mill balls as they rotate and fall. The adaptively telescopic and adjustable synchronous slide rod 44 facilitates the adaptive telescopic and adjustable extension and retraction of the movable plug 43, which can not only ensure the stability of the ball mill balls being rotated and raised by the shrinkage groove 411, but also ensure the stable ejection of materials within the shrinkage groove 411 range, reducing material adhesion within the shrinkage groove 411 range. The connecting rod 34 connects the spiral conveyor cylinder 32 and the ball mill cylinder 41, which can facilitate the use of the rotational power of the ball mill cylinder 41 to realize the rotational discharge of the spiral conveyor cylinder 32.

[0143] This allows for the adaptive contraction of the movable plug 43 and the rotational discharge of the spiral conveyor 32 simultaneously while the ball mill cylinder 41 is rotated and adjusted, thus enabling automatic maintenance and stable material discharge during continuous operation of the equipment.

[0144] In this embodiment, the ball mill cylinder 41, the feed tube seat 21, and the spiral conveyor cylinder 32 are interconnected.

[0145] Please see Figure 1 The switching mechanism 5 includes a first telescopic member 51 and a switch plate 52. The fixed part of the first telescopic member 51 is fixed on the ball mill cylinder 41, and the switch plate 52 is slidably mounted on the ball mill cylinder 41. The telescopic part of the first telescopic member 51 is fixedly connected to the switch plate 52.

[0146] In this embodiment, the ball mill cylinder 41 is provided with an installation port for supporting the ball mill balls to be inserted into the range of the ball mill cylinder 41; the switch plate 52 is aligned with the range of the installation port.

[0147] The telescopic member 51 facilitates the telescopic adjustment of the switch plate 52, thereby facilitating the switching adjustment of the switch plate 52 and enabling the installation or replacement of the grinding balls inside the grinding cylinder 41.

[0148] In this embodiment, the first telescopic member 51 can be a hydraulic telescopic cylinder, used to drive the switch plate 52 to adjust its extension and retraction stably.

[0149] Please refer to the following: Figure 1 and Figure 3 The drive mechanism 6 includes a second drive member 61 and a first synchronous wheel member 62. The fixed part of the second drive member 61 is fixed on the mounting base 1, and the first synchronous wheel member 62 is connected to the drive part of the second drive member 61 and the ball mill cylinder 41.

[0150] The second drive component 61 can conveniently and synchronously drive the ball mill cylinder 41 to rotate and adjust through the first synchronous wheel component 62, providing power for the stable rotation of the ball mill cylinder 41 on the feed tube seat 21 and the discharge tube seat 31, and ensuring the stability of the operation of the ball mill cylinder 41.

[0151] In this embodiment, the second driving component 61 is a motor structure used to drive the ball mill cylinder 41 to rotate.

[0152] In this embodiment, the first synchronizing pulley 62 includes two pulley sets and two belts. One pulley set is fixed to the driving part of the second driving member 61, and the other pulley set is fixed to the surface of the ball mill cylinder 41. The two belts drive the two pulley sets. This facilitates the stable rotation of the ball mill cylinder 41 via the second driving member 61.

[0153] Please refer to the following: Figure 2 and Figure 5 The ball mill also includes a feeding mechanism 7, which includes a feeding box 71, a guide plate 72, a movable filter plate 73, a third drive member 74, and a cam 75. The output end of the feeding box 71 is fixed at the inlet of the feed pipe seat 21. The guide plate 72 is fixed inside the feeding box 71. One end of the movable filter plate 73 is rotatably installed inside the feeding box 71. The fixing part of the third drive member 74 is fixed outside the feeding box 71. The driving part of the third drive member 74 passes through the feeding box 71 and is fixedly connected to the cam 75. The top of the cam 75 is supported at the other end of the movable filter plate 73.

[0154] It also includes a drainage mechanism 8, which includes a discharge pipe 81 and a conveyor belt assembly 82. The discharge pipe 81 is fixedly connected to one side of the feeding box 71. One end of the conveyor belt assembly 82 is fixed to the shaft end of the third drive member 74. The other end of the conveyor belt assembly 82 is rotatably installed in the discharge pipe 81. The conveying surface of the conveyor belt assembly 82 is located within the material falling range of the movable filter plate 73.

[0155] The feed box 71 is used to receive the ball mill raw materials. After being guided by the guide plate 72, the ball mill raw materials enter the vibrating screening range of the movable filter plate 73, so that qualified materials are directly conveyed into the interior of the feed pipe seat 21 through the movable filter plate 73. Unqualified materials are guided by the movable filter plate 73 and enter the conveying range of the conveyor belt assembly 82. The conveyor belt assembly 82 conveys the unqualified materials to the range of the discharge pipe 81 for independent discharge, which facilitates the vibration screening, separate conveying and discharge of the raw materials input into the range of the feed box 71.

[0156] In this embodiment, the third driving component 74 can be an independent motor structure, used to simultaneously drive the cam 75 and the conveyor belt assembly 82 to rotate.

[0157] In this embodiment, the conveyor belt assembly 82 includes two rollers and a conveyor belt. One roller is fixed to the drive part of the third drive member 74, and the other roller is rotatably installed within the range of the discharge pipe 81. The conveyor belt drives the two rollers, and the conveyor belt facilitates the reception and separate conveying of the isolated material separated by the movable filter plate 73.

[0158] Please refer to the following: Figure 2 , Figure 3 (a) and Figure 6 The ball mill also includes a cleaning mechanism 9, which includes a rotating shaft 91, a support 92, a cleaning block 93, and a second elastic element 94. One end of the rotating shaft 91 passes through the feed pipe seat 21 and the feed box 71 and is fixedly connected to the driving part of the third driving element 74. One end of the support 92 is fixed on the rotating shaft 91. The cleaning block 93 is slidably installed in the support 92. The second elastic element 94 elastically connects the rotating shaft 91 and the cleaning block 93. The top of the cleaning block 93 abuts against the inner side of the ball mill cylinder 41.

[0159] In this embodiment, the second elastic element 94 can be a spring structure, used to elastically connect the cleaning block 93 and the rotating shaft 91;

[0160] The cleaning block 93 has a brush structure and is slidably sealed within the range of the bracket 92.

[0161] When the cleaning block 93 is aligned upwards with the top of the inner wall of the ball mill cylinder 41, the cleaning block 93 abuts against the inner wall of the ball mill cylinder 41, enabling the roller brush maintenance of the inner wall of the ball mill cylinder 41.

[0162] While driving the cam 75 to rotate, the third driving component 74 can not only synchronously control the rotation and conveying of the conveyor belt assembly 82, but also synchronously drive the rotating shaft 91 to rotate. The rotating shaft 91 drives the bracket 92, the cleaning block 93 and the second elastic component 94 to rotate. While the cleaning block 93 rotates, it cleans and maintains the inner wall of the ball mill cylinder 41, so as to automatically maintain the ball mill cylinder 41 during operation, extend the service life of the equipment and reduce the adhesion of raw materials to the inner wall.

[0163] The working principle of the ball mill provided in this embodiment is as follows:

[0164] A1. When feeding, the third drive component 74 is activated, which drives the cam 75 to rotate. When the cam 75 rotates, it drives the movable filter plate 73 to vibrate up and down, which is used for vibration screening and isolation of the raw material above the movable filter plate 73. Qualified materials directly pass through the movable filter plate 73 and enter the conveying range of the feed pipe seat 21.

[0165] At the same time, the third driving component 74 also drives the conveyor belt assembly 82 to rotate. When the conveyor belt assembly 82 rotates, it receives the isolated material and then conveys it to the range of the discharge pipe 81 for independent conveying and discharge.

[0166] At the same time, the third driving member 74 also drives the rotating shaft 91 to rotate. The rotating shaft 91 drives the bracket 92, the cleaning block 93 and the second elastic member 94 to rotate as a whole. When the cleaning block 93 rotates to the top, the top of the cleaning block 93 contacts the inner wall of the ball mill cylinder 41 or the surface of the movable plug 43. Through the rolling cleaning of the cleaning block 93, the cleaning and maintenance of the inner wall of the ball mill cylinder 41 and the surface of the movable plug 43 are achieved.

[0167] A2, When feeding, the first drive unit 22 is started, the first drive unit 22 drives the spiral conveying rod 23 to rotate, and the spiral conveying rod 23 drives the raw material entering the range of the feed tube seat 21 to be conveyed towards the range of the ball mill cylinder 41;

[0168] A3. During ball milling, the second drive unit 61 is activated. The second drive unit 61 drives the ball mill cylinder 41 to rotate through the first synchronous wheel 62. The ball mill cylinder 41 drives the shrinkage groove 411 to rotate and adjust, so as to raise some of the ball mill balls and increase the height of the ball mill rotation and throwing.

[0169] When the ball mill cylinder 41 rotates, it drives the synchronous slide rod 44 to rotate. The synchronous slide rod 44 rotates and slides within the range of the transmission ring 45, so that the synchronous slide rod 44 can adaptively extend and retract.

[0170] When the synchronous slide bar 44 retracts, it facilitates the stable rotation and lifting of the mill ball.

[0171] When the synchronous slide bar 44 extends, it facilitates the ejection of raw materials within the shrinkage groove 411, so as to avoid the accumulation of raw materials in the shrinkage groove 411 affecting the lifting of the ball mill ball;

[0172] A4. During discharge, the ball mill cylinder 41 also synchronously drives the connecting rod 34 to rotate, the connecting rod 34 drives the spiral conveyor cylinder 32 to rotate, and the spiral conveyor cylinder 32 drives the filter baffle 33 to rotate as a whole, for discharging the ball milled material.

[0173] Second embodiment:

[0174] Please see Figure 7 Based on the ball mill provided in the first embodiment of the present invention, the second embodiment of the present invention proposes another ball mill. The second embodiment is merely a preferred embodiment of the first embodiment, and the implementation of the second embodiment will not affect the separate implementation of the first embodiment.

[0175] Specifically, the ball mill provided in the second embodiment of the present invention differs in that the third driving member 74 includes a synchronous shaft 741 and a second synchronous wheel 742. The synchronous shaft 741 passes through the feed box 71 and is rotatably connected to it. The second synchronous wheel 742 is hygienically connected to the driving part of the first driving member 22 and the synchronous shaft 741.

[0176] The synchronous shaft 741 is fixedly connected to the cam 75, one end of the conveyor belt assembly 82 is fixedly connected to the synchronous shaft 741, and one end of the rotating shaft 91 is fixedly connected to the synchronous shaft 741.

[0177] In an optional embodiment, the second synchronizing pulley 742 may include two pulleys and a belt. One pulley is fixed to the driving part of the first driving member 22, and the other pulley is fixedly connected to the synchronizing shaft 741. The belt drives the two pulleys.

[0178] In another alternative embodiment, the second synchronizing wheel 742 may also include two sprockets and a chain, with one sprocket fixed to the driving part of the first driving member 22 and the other sprocket fixedly connected to the synchronizing shaft 741, and the chain driving connection between the two sprockets.

[0179] To facilitate the simultaneous rotation of the synchronous shaft 741 by the second synchronous wheel 742 during the spiral conveying process controlled by the first driving component 22 of the spiral conveying rod 23, the vibration screening and isolation of the incoming material, the spiral conveying and discharge of the isolated material, and the rotating brush cleaning of the cleaning block 93 driven by the rotating shaft 91 are all achieved, thus facilitating the continuous operation and maintenance of the equipment.

[0180] In this embodiment, a space is reserved between the first driving component 22 and the feed tube seat 21 to provide installation space for the second synchronous wheel component 742.

[0181] The working principle of the ball mill provided in this embodiment:

[0182] During the pre-run of the equipment, the first drive unit 22 is started. The first drive unit 22 drives the spiral conveying rod 23 to rotate, which drives the material entering the feed tube seat 21 to be conveyed by the spiral, so that the material can enter the range of the ball mill cylinder 41 through the feed tube seat 21.

[0183] At the same time, the driving part of the first driving member 22 drives the synchronous shaft 741 to rotate synchronously through the second synchronous wheel 742. When the synchronous shaft 741 rotates, it synchronously drives the cam 75, the conveyor belt assembly 82 and the rotating shaft 91 to rotate.

[0184] When the cam 75 rotates, it drives the movable filter plate 73 to vibrate, which facilitates the vibration screening and isolation of materials entering the feeding box 71.

[0185] When the conveyor belt assembly 82 rotates, it drives the isolated material to be conveyed in the output direction of the discharge pipe 81, which facilitates the centralized discharge of the isolated material;

[0186] When the rotating shaft 91 rotates, it drives the bracket 92, the cleaning block 93 and the second elastic element 94 to rotate as a whole, which facilitates cleaning and maintenance of the inner wall of the ball mill cylinder 41 and the surface of the movable plug 43.

[0187] Ultimately, under the control of the first driving component 22, the material conveying, vibratory screening, material discharge, and cleaning and maintenance of the ball mill cylinder 41 and the movable plug 43 are realized simultaneously, facilitating continuous operation and automatic maintenance of the equipment.

[0188] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. All equivalent structural transformations made under the concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for extracting lithium from aluminum electrolytic cell solid waste, characterized by, Includes the following steps: Step S1, raw material pretreatment, crushing and fine grinding the aluminum electrolytic cell overhaul slag to obtain grinding powder; Step S2, primary roasting to remove carbon and cyanide: The powder material is placed in a tube furnace for primary roasting treatment to obtain primary roasting slag. Step S3, secondary solid fluoride roasting: The primary roasting residue is mixed with calcium sulfate and placed in a muffle furnace for secondary roasting treatment to obtain secondary roasting residue; Step S4, water leaching and phase separation: the secondary roasted residue is added to deionized water at a liquid-to-solid ratio of 3-8:1, stirred and treated, and then filtered to obtain a first leaching solution and a first leaching residue. Step S5, one-time immersion to remove impurities: Step S51: Add calcium oxide suspension to the first soaking solution, adjust the pH to 12.0±0.2, stir for 30 minutes, and filter to obtain the filtrate; Step S52: Add sodium carbonate solution to the filtrate until no precipitate forms, then filter to obtain purified solution; Step S6, lithium phosphate extraction: After heating the purified solution and stirring, trisodium phosphate solution is added dropwise to react. After filtration, the precipitate is washed with hot water to obtain lithium phosphate precipitate. Step S7, Lithium dihydrogen phosphate synthesis; Lithium phosphate is mixed with concentrated phosphoric acid, stirred and reacted, then evaporated and crystallized, and dried to obtain lithium dihydrogen phosphate.

2. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 1, characterized in that, In step S1, the crushing and fine grinding process involves coarse crushing to a particle size ≤5mm using a jaw crusher, followed by fine grinding to 80-200 mesh using a ball mill.

3. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 1, characterized in that, In step S2, oxygen is introduced during the first-stage roasting, and the temperature is increased to 500-800℃ at a rate of 5℃ / min and held for 1-4 hours. The lithium fluoride is basically not lost, which promotes the removal of carbon and the cyanide decomposition rate is >99.8%.

4. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 3, characterized in that, The oxygen concentration ranges from 20% to 100%.

5. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 1, characterized in that, In step S3, calcium sulfate is added to the secondary roasted slag according to the ratio of n(Ca):n(F) = 1.0-1.

5.

6. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 5, characterized in that, In step S3, the secondary calcination process involves heating the temperature at 3°C / min to 400-750°C and holding it at that temperature for 1-3 hours.

7. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 1, characterized in that, In step S4, the stirring temperature is controlled at 60-90℃ and the stirring time is controlled at 1-2 hours.

8. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 1, characterized in that, In step S52, the amount of sodium carbonate solution added is 1.05 times the molar amount of calcium.

9. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 1, characterized in that, In step S6, the temperature is raised to 60-80℃, and 0.5-1.0 mol / L trisodium phosphate solution is added dropwise while stirring at 300 rpm. The reaction is carried out for 1 hour, and the precipitate is washed with hot water 2-3 times after filtration.

10. The method for extracting lithium from solid waste in an aluminum electrolysis cell according to claim 1, characterized in that, In step S7, lithium phosphate and concentrated phosphoric acid are mixed at a ratio of n(H3PO4):n(Li3PO4) = 3.05:1, the stirring temperature is 60℃, the stirring reaction time is 2 hours, and the drying temperature is 100℃.

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