An apparatus and method for recovering lithium metal from electrolytic aluminum repair slag

Abstract

The application provides a device and method for recovering metal lithium from electrolytic aluminum overhaul slag, relates to the technical field of metal material recycling, and comprises a roasting furnace body, a discharging bin, a driving mechanism and a feeding mechanism. The driving mechanism comprises a rotating shaft which is vertically and rotatably connected to the inside of the discharging bin, the surface of the rotating shaft is provided with a cam through a key groove, and the two sides of the cam are tightly attached with rotating wheels. The scheme finally realizes intermittent rotation of the cam driven by the rotating shaft, and under the cooperation of the rotating wheels and the rotating frame, the two moving seats drive two material cups to move rightward, so that the two material cups are in the material receiving and discharging states respectively. The working states of the two material cups are switched by switching the position of the protruding part of the cam, the capacity ratio of the two material cups is the same as the feeding ratio of the overhaul slag and the reaction agent, and then the overhaul slag and the reaction agent are intermittently fed in a certain ratio, so that the material amount of each batch feeding strictly meets the reaction metering ratio.

Description

Technical Field

[0001] This invention relates to the field of metal material recycling, and in particular to an apparatus and method for recovering metallic lithium from electrolytic aluminum overhaul slag. Background Technology

[0002] Electrolytic aluminum, as the dominant process in global aluminum production, achieves large-scale production by reducing molten alumina to metallic aluminum in high-temperature electrolytic cells. However, electrolytic cells are subjected to molten salt corrosion at temperatures above 950°C for extended periods, causing cracks, holes, and spalling damage to the lining material. This leads to decreased current efficiency and increased energy consumption. To ensure production stability, electrolytic cells require major overhauls every 3-5 years. The resulting waste lining material, known as "overhaul slag," contains soluble fluorides and trace amounts of cyanide and is classified as hazardous solid waste. Its harmless disposal has become a major challenge for the industry.

[0003] In related technologies, lithium in electrolytic aluminum overhaul slag mainly exists in the form of lithium fluoride. Without pretreatment, the lithium leaching rate is very low. However, existing equipment for recovering metallic lithium from electrolytic aluminum overhaul slag is not convenient for adding the slag and reactant in a specific ratio during pretreatment. Insufficient reactant will lead to a sharp drop in lithium conversion rate and incomplete solidification of fluoride, while excessive reactant will introduce impurities, resulting in a decrease in the purity of metallic lithium. Only precise addition ratios can improve the recovery efficiency of metallic lithium.

[0004] Therefore, it is necessary to provide an apparatus and method for recovering metallic lithium from the slag of electrolytic aluminum overhaul to solve the above-mentioned technical problems. Summary of the Invention

[0005] This invention provides an apparatus and method for recovering metallic lithium from electrolytic aluminum overhaul slag, which solves the problem that existing equipment for recovering metallic lithium from electrolytic aluminum overhaul slag is inconvenient to add the overhaul slag and reactant in a certain proportion during the pretreatment of the overhaul slag.

[0006] To solve the above-mentioned technical problems, the equipment for recovering metallic lithium from the overhaul slag of electrolytic aluminum provided by the present invention includes a roasting furnace body, a feeding hopper, a drive mechanism, and a feeding mechanism.

[0007] The drive mechanism includes a rotating shaft that is vertically rotatably connected to the inside of the feeding bin. A cam is connected to the surface of the rotating shaft via a keyway. Rotating wheels are closely attached to both sides of the cam. Rotating frames are rotatably connected to the surfaces of the two rotating wheels.

[0008] The feeding mechanism includes two sliding frames. A protective shell is fixedly installed on the top of the feeding hopper. The tops of the two sliding frames are fixedly connected to the top of the inner wall of the protective shell. A movable seat is slidably connected to one side of the two sliding frames. A material cup is provided on the inner side of the movable seat. A cup lid is rotatably connected to the bottom of the material cup. Springs are provided on the inner side of the two sliding frames and on the right side of the movable seat. A storage hopper is connected to the top of the protective shell.

[0009] The feeding mechanism is arranged in two sets, mirror images of each other. The two sets of feeding mechanisms are in different working states under the action of the cam. The tops of the two rotating frames are fixedly connected to the bottoms of the two moving seats respectively. The two material cups have different volumes.

[0010] Preferably, the top of the movable seat is at the same horizontal line as the bottom of the storage bin, the bottom of the cup lid is in contact with the top of the feeding bin, and the top of the feeding bin has two feeding ports.

[0011] Preferably, the rotating shaft is rotatably connected to the protective shell, and a drive motor for driving the rotating shaft to rotate is provided on the top of the protective shell.

[0012] Preferably, a cleaning mechanism is fixedly provided on the top of the movable seat. The cleaning mechanism includes a protruding plate fixedly provided on the top of the movable seat. A reciprocating frame is vertically slidably connected to the inner side of the protective shell. A rotating wheel is rotatably connected to the inner side of the reciprocating frame. A return spring is sleeved on the surface of the reciprocating frame and inside the protective shell. A piston is fixedly provided at the top of the reciprocating frame. An air cylinder is fixedly provided at the top of the protective shell. The surface of the piston is slidably connected to the inner wall of the air cylinder.

[0013] Preferably, the surface of the air cylinder is connected to an air outlet pipe, the bottom end of the air outlet pipe penetrates the top of the protective shell and extends into the interior of the protective shell, the bottom end of the air outlet pipe is connected to an air jet head, and the cleaning mechanism is arranged in two sets in a mirror image on the left and right.

[0014] Preferably, a feeding mechanism is fixedly provided on the surface of the rotating shaft and inside the feeding bin. The feeding mechanism includes a mounting bracket fixed to the surface of the rotating shaft, a scraping bracket fixed to the left side of the mounting bracket, a mixing bracket fixed to the right side of the mounting bracket, a scraper fixed to the bottom of the scraping bracket, the scraper being in contact with the inner wall of the feeding bin, a mixing plate fixed to the bottom of the mixing bracket, and a threaded feeding component fixed to the circumferential side of the bottom of the rotating shaft.

[0015] Preferably, the inner wall of the feeding hopper is rotatably connected to a screening mechanism. The screening mechanism includes a rotating ring rotatably connected to the inner wall of the feeding hopper. Two layers of screens are fixedly provided on the inner side of the rotating ring. The rotating shaft is fixedly connected to the two layers of screens. Multiple sleeves are provided on the opposite side of the two layers of screens. Each of the multiple sleeves is provided with bouncing beads. Two dispersing plates are fixedly provided on the inner wall of the feeding hopper and at the top of the screens.

[0016] Preferably, a fixed support is fixedly provided on the top of the roasting furnace body, and four connecting supports are fixedly provided on the inner side of the fixed support. The four connecting supports are fixedly connected to the periphery of the feeding hopper. Three air inlet pipes are connected to the left side of the roasting furnace body, a flue gas pipe is connected to the top of the roasting furnace body, and a feeding pipe is connected to the bottom of the feeding hopper. The feeding pipe is connected to the roasting furnace body.

[0017] A method for recovering metallic lithium from aluminum slag after an electrolytic overhaul includes the following steps:

[0018] Step S1: Crush and grind the overhaul residue, send it for analysis of its components and fluorine content, and record the state of the overhaul residue before and after crushing and grinding.

[0019] Step S2: Weigh the overhaul residue and calcium sulfate according to the fluorine content detected by the overhaul residue, add the amount of calcium sulfate according to a certain molar ratio and mix evenly, place it in the calcination furnace, and react at 600℃ for 2 hours to achieve stable solidification of fluoride.

[0020] Step S3: After roasting and cooling in step S2, the clinker is mixed with pure water at a certain solid-liquid ratio. The mixture is stirred and reacted at a certain speed in a constant temperature water bath for a period of time, and then vacuum filtered to obtain lithium-rich leachate and fluoride-containing leachate residue.

[0021] The leachate obtained in steps S4 and S3 is reduced in volume to a certain extent under reduced pressure distillation. After the liquid reaches a certain temperature, it is cooled at a constant rate of one minute until almost all sodium sulfate crystals are precipitated. After vacuum filtration, purified liquid and sodium sulfate decahydrate crystals are obtained.

[0022] Step S5: The purified solution obtained in step S4 is concentrated a second time (to ensure the concentration of Li+ ions), and the prepared sodium carbonate solution is slowly added. The solution is reacted at a constant temperature in a constant temperature water bath for a period of time to generate lithium carbonate precipitate. The precipitate is washed with hot water 2-3 times to remove residual sulfate ions and then vacuum dried at 120℃ for 2 hours to obtain industrial grade lithium carbonate.

[0023] Step S6: Mix the industrial-grade lithium carbonate obtained in step S5 with lithium chloride, and perform molten salt electrolysis in a closed electrolytic cell at about 450°C. Lithium ions are reduced to molten metallic lithium at the cathode and float on the molten salt. Finally, the ingot is collected under argon protection to obtain the metallic lithium product.

[0024] Compared with related technologies, the equipment and method for recovering metallic lithium from electrolytic aluminum overhaul slag provided by this invention have the following beneficial effects:

[0025] The rotating shaft drives the cam to rotate intermittently. With the cooperation of the rotating wheel and the rotating frame, the two moving seats drive the two material cups to move to the right, so that the two material cups are in the receiving and discharging state respectively. By reciprocating and switching the position of the cam protrusion, the working state of the two material cups is switched. The capacity ratio of the two material cups is the same as the feeding ratio of overhaul slag and reactant. Then, the overhaul slag and reactant are fed intermittently according to a certain ratio to ensure that the amount of material fed in each batch strictly conforms to the reaction metering ratio. This avoids incomplete fluorine solidification due to insufficient reactant or impurity interference due to excessive reactant, thereby improving the purity of lithium metal recovery. At the same time, the overhaul slag and reactant powder are prone to electrostatic agglomeration. Intermittent small-batch feeding can reduce the formation of agglomerates. The material falls into the screen by gravity, further breaking up the agglomerated particles and ensuring full contact between the overhaul slag and reactant, thereby further improving the lithium metal recovery effect. Attached Figure Description

[0026] 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.

[0027] Figure 1 The optimal structural schematic diagram provided for this invention;

[0028] Figure 2 This is a structural schematic diagram of a cross-sectional view of the feeding hopper provided by the present invention;

[0029] Figure 3 A schematic diagram of the drive mechanism provided by the present invention;

[0030] Figure 4 This is a schematic diagram of the dosing mechanism provided by the present invention;

[0031] Figure 5 A schematic diagram showing the state in which the rotating shaft drives the cam to rotate, causing the right-side cup to move to the right;

[0032] Figure 6 A schematic diagram of the cleaning mechanism provided by the present invention;

[0033] Figure 7 for Figure 6 The diagram shows a structural schematic of the cross-sectional view of the air cylinder.

[0034] Figure 8This is a schematic diagram of the feeding mechanism provided by the present invention;

[0035] Figure 9 A schematic diagram of the screening mechanism provided by the present invention;

[0036] Figure 10 This is a schematic diagram of the method flow provided by the present invention.

[0037] Explanation of icon numbers:

[0038] 1. Firing furnace body; 2. Feeding hopper;

[0039] 3. Drive mechanism; 31. Rotating shaft; 32. Cam; 33. Rotating wheel; 34. Rotating frame; 35. Drive motor;

[0040] 4. Feeding mechanism; 41. Sliding frame; 42. Movable seat; 43. Material cup; 44. Cup lid; 45. Spring; 46. Storage bin;

[0041] 5. Protective casing;

[0042] 6. Cleaning mechanism; 61. Convex plate; 62. Reciprocating frame; 63. Rotary wheel; 64. Return spring; 65. Piston; 66. Air cylinder; 67. Air outlet pipe; 68. Air jet head;

[0043] 7. Feeding mechanism; 71. Mounting bracket; 72. Scraping bracket; 73. Mixing bracket; 74. Scraper; 75. Mixing plate; 76. Threaded feeding component;

[0044] 8. Screening mechanism; 81. Rotating ring; 82. Screen; 83. Sleeve; 84. Bouncing beads; 85. Dispersion plate;

[0045] 9. Fixed bracket; 10. Connecting bracket; 11. Air inlet pipe; 12. Flue gas pipe; 13. Dosing pipe. Detailed Implementation

[0046] 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.

[0047] This invention provides an apparatus and method for recovering metallic lithium from the slag of an electrolytic aluminum overhaul.

[0048] First embodiment:

[0049] Please see Figures 1 to 5A device for recovering metallic lithium from the overhaul slag of electrolytic aluminum includes a roasting furnace body 1, a feeding bin 2, a drive mechanism 3, and a feeding mechanism 4.

[0050] The drive mechanism 3 includes a rotating shaft 31 that is vertically rotatably connected to the inside of the feeding bin 2. A cam 32 is connected to the surface of the rotating shaft 31 via a keyway. Rotating wheels 33 are tightly attached to both sides of the cam 32. A rotating frame 34 is rotatably connected to the surface of each of the two rotating wheels 33.

[0051] The rotating shaft 31 is rotatably connected to the protective shell 5, and a drive motor 35 for driving the rotating shaft 31 to rotate is provided on the top of the protective shell 5.

[0052] Please combine Figure 3 Start the drive motor 35. The drive motor 35 rotates, which drives the rotating shaft 31 to rotate. The rotating shaft 31 rotates, which drives the cam 32 to rotate intermittently.

[0053] The feeding mechanism 4 includes two sliding frames 41. A protective shell 5 is fixedly installed on the top of the feeding bin 2. The tops of the two sliding frames 41 are fixedly connected to the top of the inner wall of the protective shell 5. A movable seat 42 is slidably connected to the opposite side of the two sliding frames 41. A material cup 43 is provided on the inner side of the movable seat 42. A cup lid 44 is rotatably connected to the bottom of the material cup 43. A spring 45 is provided on the inner side of the two sliding frames 41 and on the right side of the movable seat 42. A storage bin 46 is connected to the top of the protective shell 5.

[0054] The feeding mechanism 4 is arranged in two sets in a left-right mirror image. The two sets of feeding mechanisms 4 are in different working states under the action of cam 32. The tops of the two rotating frames 34 are fixedly connected to the bottoms of the two moving seats 42 respectively. The two material cups 43 have different volumes.

[0055] The top of the movable seat 42 is at the same level as the bottom of the storage bin 46, the bottom of the cup lid 44 is in contact with the top of the feeding bin 2, and the top of the feeding bin 2 has two feeding ports.

[0056] Please combine Figure 4 and Figure 5 When the protruding part of the cam 32 rotates to the right, it will push the right rotating frame 34 to the right through the right rotating wheel 33. The rotation frame 34 moves to the right, causing the right moving seat 42 to slide to the right inside the sliding frame 41. The right moving seat 42 moves to the right, which in turn causes the material cup 43 and the cup lid 44 to move to the right. When the cup lid 44 moves to the position of the discharge port, the cup lid 44 will rotate downward, thereby feeding the material in the material cup 43 onto the top of the screen 82.

[0057] Furthermore, when the protruding part of the cam 32 rotates to the right, the left movable seat 42 will reset to the right under the action of the spring 45. The movement of the left movable seat 42 drives the inner material cup 43 and cup cover 44 to move to the right, so that the left material cup 43 moves to the bottom of the left storage bin 46. Through the intermittent rotation of the cam 32, the two material cups 43 are intermittently fed. The two material cups 43 respectively store the overhaul residue and the reactant. The capacity ratio of the two material cups 43 is the same as the feeding ratio of the overhaul residue and the reactant, so that the overhaul residue and the reactant are intermittently fed in a certain ratio.

[0058] Preferably, the bottom of the storage bin 46 is made of rubber. The initial positions of the two material cups 43 are one at the bottom of the storage bin 46 and the other at the top of the feed inlet. During the intermittent rotation of the cam 32, one material cup 43 is in the receiving state and the other material cup 43 is in the discharging state.

[0059] In this embodiment, the rotating shaft 31 drives the cam 32 to rotate intermittently. With the cooperation of the rotating wheel 33 and the rotating frame 34, the two moving seats 42 drive the two material cups 43 to move to the right, so that the two material cups 43 are in the receiving and discharging state respectively. By reciprocating and switching the position of the protrusion of the cam 32, the working state of the two material cups 43 is switched. The capacity ratio of the two material cups 43 is the same as the feeding ratio of the overhaul slag and the reactant. Then, the overhaul slag and the reactant are fed intermittently according to a certain ratio to ensure that the amount of material fed in each batch strictly conforms to the reaction metering ratio, avoiding incomplete fluorine solidification due to insufficient reactant or impurity interference due to excessive reactant, thereby improving the purity of lithium metal recovery. At the same time, the overhaul slag and reactant powder are prone to electrostatic agglomeration. Intermittent small-batch feeding can reduce the formation of agglomerates. The material falls into the screen 82 by gravity dispersion, further breaking up the agglomerated particles, ensuring that the overhaul slag and the reactant are in full contact, and further improving the lithium metal recovery effect.

[0060] Second embodiment:

[0061] Please see Figure 6 and Figure 7 A cleaning mechanism 6 is fixedly provided on the top of the movable seat 42. The cleaning mechanism 6 includes a protruding plate 61 fixedly provided on the top of the movable seat 42. A reciprocating frame 62 is vertically slidably connected to the inner side of the protective shell 5. A rotating wheel 63 is rotatably connected to the inner side of the reciprocating frame 62. A return spring 64 is sleeved on the surface of the reciprocating frame 62 and inside the protective shell 5. A piston 65 is fixedly provided on the top of the reciprocating frame 62. An air cylinder 66 is fixedly provided on the top of the protective shell 5. The surface of the piston 65 is slidably connected to the inner wall of the air cylinder 66.

[0062] The surface of the air cylinder 66 is connected to an air outlet pipe 67. The bottom end of the air outlet pipe 67 penetrates the top of the protective shell 5 and extends into the interior of the protective shell 5. The bottom end of the air outlet pipe 67 is connected to a jet nozzle 68. The cleaning mechanism 6 is arranged in two sets on the left and right sides in a mirror image.

[0063] Please combine Figure 6 and Figure 7 When the right movable seat 42 moves to the right, it will simultaneously drive the top convex plate 61 to move to the right. When the material cup 43 is located at the feeding port and continues to move to the right, the convex plate 61 will push the reciprocating frame 62 upward through the rotating wheel 63. The upward movement of the reciprocating frame 62 will drive the piston 65 to slide upward on the inner wall of the air cylinder 66, thereby spraying the gas in the air cylinder 66 downward through the air outlet pipe 67 and the jet nozzle 68. The gas sprayed out by the jet nozzle 68 can blow the powder remaining in the material cup 43 into the feeding bin 2.

[0064] Furthermore, when the right movable seat 42 moves to the right, the left movable seat 42 will move to the right at the same time. The rightward movement of the left movable seat 42 will drive the top protrusion 61 to move to the right. Under the action of the return spring 64, the reciprocating frame 62 will drive the piston 65 to slide downward inside the air cylinder 66 to draw out the outside air.

[0065] Preferably, the two jet heads 68 are located at the top of the two discharge ports, and the top of the air cylinder 66 is connected to an air extraction pipe. Both the air extraction pipe and the air outlet pipe 67 are provided with one-way valves.

[0066] In this embodiment, when the rotating shaft 31 drives the cam 32 to rotate intermittently and the position of the protrusion of the cam 32 is switched, the two air cylinders 66 will be in the suction and blowing states respectively. The suction state is used to cooperate with the receiving state of the material cup 43, and the blowing state is used to cooperate with the discharging state of the material cup 43. By blowing air into the material cup 43 after the material has been discharged, the airflow generated by blowing can directly blow the powder remaining on the cup wall into the feeding bin 2, further improving the accuracy of the material feeding ratio and providing further assurance for the recovery effect of lithium metal.

[0067] Third embodiment:

[0068] Please see Figure 1 , Figure 8 and Figure 9 A feeding mechanism 7 is fixedly provided on the surface of the rotating shaft 31 and inside the feeding bin 2. The feeding mechanism 7 includes a mounting frame 71 fixedly provided on the surface of the rotating shaft 31. A scraping bracket 72 is fixedly provided on the left side of the mounting frame 71, and a mixing bracket 73 is fixedly provided on the right side of the mounting frame 71. A scraper 74 is fixedly provided at the bottom of the scraping bracket 72. The scraper 74 is in contact with the inner wall of the feeding bin 2. A mixing plate 75 is fixedly provided at the bottom of the mixing bracket 73. A threaded feeding component 76 is fixedly provided on the circumferential side of the bottom of the rotating shaft 31.

[0069] Please combine Figure 8 When the rotating shaft 31 rotates intermittently, it will simultaneously drive the scraping bracket 72 and the mixing bracket 73 to rotate intermittently. The rotation of the scraping bracket 72 will drive the scraper 74 to clean the inner wall of the feeding bin 2 to prevent powder from adhering. The rotation of the mixing bracket 73 will drive the mixing plate 75 to rotate, thereby mixing the material. When the rotating shaft 31 rotates, it will simultaneously drive the threaded feeding component 76 to rotate, thereby feeding the mixed material through the rotation of the threaded feeding component 76.

[0070] The inner wall of the feeding hopper 2 is rotatably connected to a screening mechanism 8. The screening mechanism 8 includes a rotating ring 81 rotatably connected to the inner wall of the feeding hopper 2. Two layers of screens 82 are fixedly provided on the inner side of the rotating ring 81. The rotating shaft 31 is fixedly connected to the two layers of screens 82. Multiple sleeves 83 are provided on the opposite side of the two layers of screens 82. The interior of each of the multiple sleeves 83 is provided with bouncing beads 84. Two dispersing plates 85 are fixedly provided on the inner wall of the feeding hopper 2 and at the top of the screens 82.

[0071] Please combine Figure 9 When the rotating shaft 31 drives the cam 32 to rotate intermittently, it will simultaneously drive the screen 82 and the rotating ring 81 to rotate intermittently, so that the material is not piled up in one position. When the rotating ring 81 and the screen 82 drive the material to rotate, the material can be dispersed by the setting of the dispersing plate 85. The bouncing ball 84 is used to clean the screen 82 and prevent the screen 82 from clogging.

[0072] The top of the roasting furnace body 1 is fixedly provided with a fixed support 9, and four connecting supports 10 are fixedly provided on the inner side of the fixed support 9. The four connecting supports 10 are fixedly connected to the periphery of the feeding bin 2. Three air inlet pipes 11 are connected to the left side of the roasting furnace body 1. A flue gas pipe 12 is connected to the top of the roasting furnace body 1. A feeding pipe 13 is connected to the bottom of the feeding bin 2. The feeding pipe 13 is connected to the roasting furnace body 1.

[0073] Preferably, the surface of the feeding pipe 13 is provided with a feeding valve to control the rhythm of feeding material into the roasting furnace body 1. The flue gas pipe 12 is equipped with a bag filter and an alkali absorption tower. The bag filter is used to remove dust generated during roasting, and the alkali absorption tower is used to absorb a small amount of SO3 flue gas to ensure that the exhaust gas emissions meet environmental protection requirements.

[0074] In this embodiment, when the rotating shaft 31 drives the cam 32 to rotate intermittently, it will simultaneously drive the screen 82 and the rotating ring 81 to rotate intermittently, so that the material is not piled up in the same position. Furthermore, when the rotating ring 81 and the screen 82 drive the material to rotate, the material can be further dispersed by the dispersing plate 85, improving the mixing effect of the material and ensuring that the materials can react fully, thereby improving the quality of lithium metal recovery.

[0075] Fourth embodiment:

[0076] Please see Figure 10 A method for recovering metallic lithium from aluminum slag after an electrolytic overhaul includes the following steps:

[0077] Step S1: Crush and grind the overhaul residue, send it for analysis of its components and fluorine content, and record the state of the overhaul residue before and after crushing and grinding.

[0078] Step S2: Weigh the overhaul residue and calcium sulfate according to the fluorine content detected by the overhaul residue, add the amount of calcium sulfate according to a certain molar ratio and mix evenly, place it in the calcination furnace 1, and react at 600℃ for 2 hours to achieve stable solidification of fluoride.

[0079] Step S3: After roasting and cooling in step S2, the clinker is mixed with pure water at a certain solid-liquid ratio. The mixture is stirred and reacted at a certain speed in a constant temperature water bath for a period of time, and then vacuum filtered to obtain lithium-rich leachate and fluoride-containing leachate residue.

[0080] The leachate obtained in steps S4 and S3 is reduced in volume to a certain extent under reduced pressure distillation. After the liquid reaches a certain temperature, it is cooled at a constant rate of one minute until almost all sodium sulfate crystals are precipitated. After vacuum filtration, purified liquid and sodium sulfate decahydrate crystals are obtained.

[0081] Step S5: The purified solution obtained in step S4 is concentrated a second time (to ensure the concentration of Li+ ions), and the prepared sodium carbonate solution is slowly added. The solution is reacted at a constant temperature in a constant temperature water bath for a period of time to generate lithium carbonate precipitate. The precipitate is washed with hot water 2-3 times to remove residual sulfate ions and then vacuum dried at 120℃ for 2 hours to obtain industrial grade lithium carbonate.

[0082] Step S6: Mix the industrial-grade lithium carbonate obtained in step S5 with lithium chloride, and perform molten salt electrolysis in a closed electrolytic cell at about 450°C. Lithium ions are reduced to molten metallic lithium at the cathode and float on the molten salt. Finally, the ingot is collected under argon protection to obtain the metallic lithium product.

[0083] In this embodiment, calcium sulfate reacts with fluorine compounds at high temperature to form a structurally stable fluorite structure. By precisely controlling parameters such as the temperature and time of roasting and leaching, a green recycling technology for the efficient extraction of metallic lithium from overhaul slag is achieved, realizing the stable solidification of fluorine, maximizing resource utilization, reducing waste emissions, and conforming to the concepts of green chemistry and circular economy.

[0084] Please refer to the reference again. Figures 1 to 10 The working principle of the equipment and method for recovering metallic lithium from electrolytic aluminum overhaul slag provided by this invention is as follows:

[0085] Step S1: The ground overhaul residue and the reactant are fed into two storage bins 46 respectively. Then, the drive motor 35 is started. The drive motor 35 rotates and drives the rotating shaft 31 to rotate. The rotating shaft 31 rotates and drives the cam 32 to rotate intermittently.

[0086] When the protruding part of the cam 32 rotates to the right, it will push the right rotating frame 34 to the right through the right rotating wheel 33. The rotation frame 34 moves to the right, causing the right moving seat 42 to slide to the right inside the sliding frame 41. The right moving seat 42 moves to the right, causing the material cup 43 and the cup lid 44 to move to the right. When the cup lid 44 moves to the position of the discharge port, the cup lid 44 will rotate downward, feeding the material in the material cup 43 to the top of the screen 82.

[0087] When the protruding part of the cam 32 rotates to the right, the left movable seat 42 will return to the right under the action of the spring 45. The movement of the left movable seat 42 drives the inner material cup 43 and cup cover 44 to move to the right, so that the left material cup 43 moves to the bottom of the left storage bin 46. Through the intermittent rotation of the cam 32, the two material cups 43 are intermittently fed. The two material cups 43 respectively store the overhaul residue and the reactant. The capacity ratio of the two material cups 43 is the same as the feeding ratio of the overhaul residue and the reactant. Thus, the overhaul residue and the reactant are intermittently fed in a certain ratio.

[0088] In step S2, combined with step S1, when the right moving seat 42 moves to the right, it will simultaneously drive the top protruding plate 61 to move to the right. When the material cup 43 is located at the feeding port and continues to move to the right, the protruding plate 61 will push the reciprocating frame 62 upward through the rotating wheel 63. The reciprocating frame 62 moves upward and drives the piston 65 to slide upward on the inner wall of the air cylinder 66, and sprays the gas in the air cylinder 66 downward through the air outlet pipe 67 and the jet nozzle 68. The gas sprayed out by the jet nozzle 68 can blow the powder remaining in the material cup 43 into the feeding bin 2.

[0089] When the right movable seat 42 moves to the right, the left movable seat 42 will move to the right at the same time. The rightward movement of the left movable seat 42 will drive the top protrusion 61 to move to the right. Under the action of the return spring 64, the reciprocating frame 62 will drive the piston 65 to slide downward inside the air cylinder 66 to draw out the outside air.

[0090] In step S3, combined with step S1, when the rotating shaft 31 rotates intermittently, it will simultaneously drive the scraping bracket 72 and the mixing bracket 73 to rotate intermittently. The rotation of the scraping bracket 72 will drive the scraper 74 to clean the inner wall of the feeding bin 2. The rotation of the mixing bracket 73 will drive the mixing plate 75 to rotate, thereby mixing the material. When the rotating shaft 31 rotates, it will simultaneously drive the threaded feeding part 76 to rotate. The mixed material will be fed into the calcining furnace body 1 through the rotation of the threaded feeding part 76. The material will react at 600°C for two hours to achieve stable solidification of fluoride.

[0091] In step S4, when the rotating shaft 31 drives the cam 32 to rotate intermittently, it will simultaneously drive the screen 82 and the rotating ring 81 to rotate intermittently, so that the material being fed will not accumulate in one position. When the rotating ring 81 and the screen 82 drive the material to rotate, the material can be dispersed by the setting of the dispersing plate 85. The bouncing beads 84 are used to clean the screen 82 and prevent the screen 82 from clogging.

[0092] 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 roasting device for recovering metallic lithium from electrolytic aluminum overhaul slag, characterized in that, This includes the roasting furnace body, feeding hopper, drive mechanism, and feeding mechanism; The drive mechanism includes a rotating shaft that is vertically rotatably connected to the inside of the feeding bin. A cam is connected to the surface of the rotating shaft via a keyway. Rotating wheels are tightly attached to both sides of the cam. Rotating frames are rotatably connected to the surfaces of the two rotating wheels. The feeding mechanism includes two sliding frames. A protective shell is fixedly installed on the top of the feeding hopper. The tops of the two sliding frames are fixedly connected to the top of the inner wall of the protective shell. A movable seat is slidably connected to one side of the two sliding frames. A material cup is provided on the inner side of the movable seat. A cup lid is rotatably connected to the bottom of the material cup. Springs are provided on the inner side of the two sliding frames and on the right side of the movable seat. A storage hopper is connected to the top of the protective shell. The feeding mechanism is arranged in two sets, mirror images of each other. The two sets of feeding mechanisms are in different working states under the action of the cam. The tops of the two rotating frames are fixedly connected to the bottoms of the two moving seats respectively. The two material cups have different volumes. The top of the roasting furnace body is fixedly provided with a fixed bracket, and four connecting brackets are fixedly provided on the inner side of the fixed bracket. The four connecting brackets are fixedly connected to the peripheral side of the feeding hopper. The bottom of the feeding hopper is connected to a feeding pipe, which is connected to the roasting furnace body.

2. The roasting equipment for recovering metallic lithium from electrolytic aluminum overhaul slag according to claim 1, characterized in that, The top of the movable seat is at the same level as the bottom of the storage bin, the bottom of the cup lid is in contact with the top of the feeding bin, and the top of the feeding bin has two feeding ports.

3. The roasting equipment for recovering metallic lithium from electrolytic aluminum overhaul slag according to claim 1, characterized in that, The rotating shaft is rotatably connected to the protective shell, and a drive motor for driving the rotating shaft to rotate is provided on the top of the protective shell.

4. The roasting equipment for recovering metallic lithium from electrolytic aluminum overhaul slag according to claim 1, characterized in that, A cleaning mechanism is fixedly installed on the top of the movable seat. The cleaning mechanism includes a protruding plate fixedly installed on the top of the movable seat. A reciprocating frame is vertically slidably connected to the inner side of the protective shell. A rotating wheel is rotatably connected to the inner side of the reciprocating frame. A return spring is sleeved on the surface of the reciprocating frame and inside the protective shell. A piston is fixedly installed at the top of the reciprocating frame. An air cylinder is fixedly installed at the top of the protective shell. The surface of the piston is slidably connected to the inner wall of the air cylinder.

5. The roasting equipment for recovering metallic lithium from electrolytic aluminum overhaul slag according to claim 4, characterized in that, The surface of the air cylinder is connected to an air outlet pipe, the bottom end of which penetrates the top of the protective shell and extends into the interior of the protective shell. The bottom end of the air outlet pipe is connected to an air jet head. The cleaning mechanism is arranged in two sets, mirrored on the left and right sides.

6. The roasting equipment for recovering metallic lithium from electrolytic aluminum overhaul slag according to claim 1, characterized in that, A feeding mechanism is fixedly installed on the surface of the rotating shaft and inside the feeding bin. The feeding mechanism includes a mounting bracket fixed to the surface of the rotating shaft. A scraping bracket is fixedly installed on the left side of the mounting bracket, and a mixing bracket is fixedly installed on the right side of the mounting bracket. A scraper is fixedly installed at the bottom of the scraping bracket and the scraper is in contact with the inner wall of the feeding bin. A mixing plate is fixedly installed at the bottom of the mixing bracket, and a threaded feeding component is fixedly installed on the circumferential side of the bottom of the rotating shaft.

7. The roasting equipment for recovering metallic lithium from electrolytic aluminum overhaul slag according to claim 1, characterized in that, The inner wall of the feeding hopper is rotatably connected to a screening mechanism. The screening mechanism includes a rotating ring rotatably connected to the inner wall of the feeding hopper. Two layers of screens are fixedly provided on the inner side of the rotating ring. The rotating shaft is fixedly connected to the two layers of screens. Multiple sleeves are provided on the opposite side of the two layers of screens. Each of the multiple sleeves is provided with bouncing beads. Two dispersing plates are fixedly provided on the inner wall of the feeding hopper and at the top of the screens.

8. The roasting equipment for recovering metallic lithium from electrolytic aluminum overhaul slag according to claim 1, characterized in that, The left side of the roasting furnace body is connected to three air inlet pipes, and the top of the roasting furnace body is connected to a flue gas pipe.

9. A method for recovering metallic lithium from electrolytic aluminum overhaul slag, characterized in that, The method for recovering lithium metal includes the roasting equipment for recovering lithium metal as described in any one of claims 1-8 and the following steps: Step S1: Crush and grind the overhaul residue, send it for analysis of its components and fluorine content, and record the state of the overhaul residue before and after crushing and grinding. Step S2: Weigh the overhaul residue and calcium sulfate according to the fluorine content detected by the overhaul residue. Through the drive mechanism and the feeding mechanism, the overhaul residue and calcium sulfate are mixed evenly according to a certain molar ratio and the amount of calcium sulfate added. The mixture is placed in the calcination furnace and reacted at 600℃ for 2 hours to achieve stable solidification of fluoride. Step S3: After roasting and cooling in step S2, the clinker is mixed with pure water at a certain solid-liquid ratio. The mixture is stirred and reacted at a certain speed in a constant temperature water bath for a period of time, and then vacuum filtered to obtain lithium-rich leachate and fluoride-containing leachate residue. The leachate obtained in steps S4 and S3 is reduced in volume to a certain extent under reduced pressure distillation. After the liquid reaches a certain temperature, it is cooled at a uniform rate of one minute until all sodium sulfate crystals precipitate. After vacuum filtration, purified liquid and sodium sulfate decahydrate crystals are obtained. Step S5: The purified liquid obtained in step S4 is concentrated a second time, and the prepared sodium carbonate solution is slowly added. The mixture is reacted at a constant temperature in a constant temperature water bath for a period of time to generate lithium carbonate precipitate. The precipitate is washed with hot water 2-3 times to remove residual sulfate ions and then vacuum dried at 120°C for 2 hours to obtain industrial grade lithium carbonate. Step S6: Mix the industrial-grade lithium carbonate obtained in step S5 with lithium chloride, and perform molten salt electrolysis in a closed electrolytic cell at 450°C. Lithium ions are reduced to molten metallic lithium at the cathode and float on the molten salt. Finally, the ingot is collected under argon protection to obtain the metallic lithium product.

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