A deep impurity removal method for efficient separation of manganese and calcium in a lithium manganese oxide waste lithium extraction process

Abstract

This invention relates to the field of lithium extraction technology from waste materials, and in particular to a deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process from lithium manganese oxide waste. The method includes the following steps: Step 1, reduction acid leaching: Lithium manganese oxide waste is mixed with sulfuric acid and hydrogen peroxide inside a separation and adjustment device for leaching reaction, yielding a leachate containing Li⁺, Mn²⁺, and Ca²⁺; Step 2, oxidation to remove manganese: The pH of the leachate is monitored and adjusted to 5.0-5.5 using the separation and adjustment device, and an oxidant is added to oxidize Mn²⁺ to MnO₂ precipitate; Step 3, fluorination for deep calcium removal; Step 4, lithium precipitation. This device avoids lithium loss caused by the co-precipitation of manganese and calcium in traditional processes through an automated pH and temperature control system, achieving a comprehensive lithium recovery rate of over 90%. The fluorination process reduces calcium impurities to battery-grade standards, effectively solving the problem of difficult deep decalcification using conventional carbonate methods. Simultaneously, the separation and adjustment device enables clean transfer and online monitoring between each step.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction from waste materials, and more particularly to a deep impurity removal method for efficient separation of manganese and calcium during the lithium extraction process from lithium manganese oxide waste. Background Technology

[0002] The lithium extraction process from lithium manganese oxide waste refers to the key step of selectively removing impurity ions such as manganese and calcium from the lithium-containing solution obtained by acid leaching to extremely low levels through a combination of chemical precipitation and oxidation-reduction techniques, thereby achieving efficient separation of lithium from manganese and calcium. This process differs from conventional coarse impurity removal and emphasizes precise step-by-step control.

[0003] In the existing technology, when controlling the pH during the lithium extraction process, the presence of a large amount of solution in the process leads to different pH values ​​at different positions and heights inside the reactor. This results in unstable pH adjustment during the reaction process, causing different reaction degrees and thus affecting the lithium extraction effect. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a deep impurity removal method for efficient separation of manganese and calcium during the lithium extraction process from lithium manganese oxide waste.

[0005] This invention provides a deep impurity removal method for efficient separation of manganese and calcium during lithium extraction from lithium manganese oxide waste, comprising the following steps:

[0006] Step 1, Reduction Acid Leaching: Lithium manganese oxide waste is mixed with sulfuric acid and hydrogen peroxide in a separation and regulation device to carry out a leaching reaction, resulting in a leachate containing Li⁺, Mn²⁺, and Ca²⁺.

[0007] Step 2, Oxidation to remove manganese: The pH of the leachate is monitored and adjusted to 5.0-5.5 using the separation and adjustment device. An oxidant is added to oxidize Mn²⁺ to MnO₂ precipitate. MnO₂ is removed by filtration to obtain a purified solution containing Li⁺ and Ca²⁺.

[0008] Step 3, deep fluorination for calcium removal: The purified solution is transferred to the clean separation and adjustment device, and the pH of the purified solution is adjusted to 5.0-6.0 by the separation and adjustment device. Fluorinizing agent is added, and the mixture is heated and stirred to generate CaF2 precipitate. CaF2 is removed by filtration to obtain a lithium-containing purified solution, wherein the Ca²⁺ concentration is less than 10 ppm.

[0009] Step 4, Lithium precipitation: Add saturated sodium carbonate solution to the lithium-containing refined solution, heat to precipitate and obtain battery-grade lithium carbonate product;

[0010] Utilizing the differences in chemical properties among manganese, calcium, and lithium, a separation and adjustment device precisely controls the pH, temperature, and feeding conditions at each step to achieve stepwise selective precipitation and deep impurity removal. First, in the reduction acid leaching stage, sulfuric acid and hydrogen peroxide synergistically dissolve lithium, manganese, and calcium in the waste in ionic form simultaneously. Hydrogen peroxide, acting as a reducing agent, promotes manganese leaching. Then, in the oxidation manganese removal stage, the separation and adjustment device automatically stabilizes the pH at 5.0-5.5 and adds ammonium persulfate or ozone. Taking advantage of the easy oxidation of Mn²⁺ to MnO₂ precipitate under heating conditions, manganese is separated as high-purity manganese slag, while lithium and calcium remain in the solution. Next, in the fluorination deep calcium removal stage, the separation and adjustment device precisely adjusts the pH to 5.0-6.0 and adds manganese fluoride or sodium fluoride. Based on the extremely low solubility product of CaF₂, calcium ions are preferentially precipitated as calcium fluoride, while lithium ions are almost not lost due to the relatively high solubility of lithium fluoride, thus achieving a calcium removal depth of 10. Below ppm, saturated sodium carbonate is added in the final lithium precipitation stage to obtain battery-grade lithium carbonate products. The automated pH and temperature control system avoids lithium loss caused by manganese and calcium co-precipitation in traditional processes, enabling a comprehensive lithium recovery rate of over 90%. The fluorination calcium removal process can reduce calcium impurities to battery-grade standards, which helps solve the problem of deep decalcification that is difficult to achieve with conventional carbonate methods. At the same time, the separation and adjustment device realizes clean transfer and online monitoring between each step, reducing human operation errors and cross-contamination.

[0011] Preferably, the separation adjustment device includes:

[0012] A reaction vessel, wherein a sealing cover is detachably and fixedly installed on the top of the reaction vessel and a support is fixedly installed on the bottom;

[0013] The motor is fixed to the top of the sealing cover;

[0014] The first rotating shaft is rotatably mounted on the bottom of the sealing cover and located inside the reactor. The motor drives the first rotating shaft to rotate through the output shaft.

[0015] Multiple stirring rods are installed on the outer wall of the first rotating shaft, and a pH meter is installed at the end of each stirring rod;

[0016] A variable speed drive assembly is installed between the first rotating shaft and the reactor. It drives the internal liquid to flow longitudinally along the interior of the reactor through the speed difference, so as to achieve uniform stirring.

[0017] When adjusting the pH of the reactants inside the reactor, the motor drives the first rotating shaft connected to it to rotate via the output shaft. The first rotating shaft drives the stirring rod to rotate, and the stirring rod stirs the reactants. At the same time, the pH of the reactants after uniform stirring is monitored by a pH detector at the end, which helps to improve the accuracy of pH detection. When a pH deviation is detected, acid or alkali solution is slowly added into the reactor while stirring, which helps to slowly adjust the acid or alkali during stirring. This helps to avoid local pH changes affecting the reaction effect. Furthermore, the variable speed drive component can automatically drive the reactants to achieve vertical flow and stirring inside the reactor, thereby further increasing the uniformity of the reactants, making the internal pH uniform and accurately adjusted, and improving the reaction effect.

[0018] Preferably, the transmission drive assembly includes:

[0019] The second rotating shaft is rotatably installed inside the reactor.

[0020] The rotating support is fixed to the bottom of the second rotating shaft and rotatably installed at the bottom of the inside of the reactor.

[0021] The first arc-shaped plate is detachably installed inside the reactor;

[0022] The guide plate is fixed above the first arc-shaped plate by a connecting frame and is located inside the reactor, forming a liquid flow guiding path with the first arc-shaped plate;

[0023] A speed-changing component is installed between the first rotating shaft and the second rotating shaft. It drives the second rotating shaft by accelerating its rotation, thereby driving the liquid flow toward the first arc-shaped plate to form a liquid flow along the guide path.

[0024] After the first shaft rotates, the stirring rod on the second shaft rotates at high speed through the speed-changing component. The high-speed rotation of the stirring rod aligns with the first arc-shaped plate, increasing the centrifugal force on the reactants. This increased centrifugal force causes the reactants to impact the first arc-shaped plate and flow upward along it under its guidance. As the plate guides the reactants upward, they reach the top of the plate and thus guide the flow path of the reactants, improving their uniformity and enhancing the pH adjustment effect.

[0025] Preferably, the transmission component includes:

[0026] The box body is rotatably mounted on the top of the second rotating shaft, and its edges are fixedly connected to the guide plate by a support rod;

[0027] The lid is rotatably mounted on the bottom of the first rotating shaft;

[0028] The first gear is rotatably installed inside the housing and is connected to the first rotating shaft via a first plug-in rod.

[0029] The fourth gear is rotatably mounted inside the housing and is connected to the second rotating shaft via a second connector rod.

[0030] The second and third gears are coaxially and rotatably mounted inside the housing, and the first gear meshes with the second gear, the fourth gear meshes with the third gear, and the diameter of the first gear and the fourth gear is greater than the diameter of the second gear and the fourth gear;

[0031] After the first rotating shaft is installed, the first connecting rod at the bottom of the first rotating shaft is connected to the first gear, so that the first gear can be rotated after rotation. The first gear drives the second gear to rotate, the second gear drives the third gear to rotate, and the third gear drives the fourth gear that meshes with it to rotate. The bottom of the fourth gear is connected to the second rotating shaft through the second connecting rod to drive the second rotating shaft to rotate. At the same time, by setting the diameter ratio of the first gear, the second gear, the third gear, and the fourth gear, the rotation speed of the second rotating shaft can be increased, thereby driving the stirring rod on the second rotating shaft to rotate at high speed and causing the reactants to flow vertically.

[0032] Preferably, the transmission drive assembly further includes:

[0033] The second arc-shaped plate is installed inside the reactor, with the center of the groove aligned with the top of the guide plate and a gap left between them;

[0034] The second arc-shaped plate allows the reactants, after being guided upward by the guide plate, to flow downward by the arc-shaped guidance of the second arc-shaped plate, thereby further increasing the circulation of the reactants and improving the uniformity.

[0035] Preferably, the transmission drive assembly further includes:

[0036] Two connecting plates are symmetrically inserted into the grooves opened in the inner wall of the reactor, and their side walls are respectively fixedly connected to the guide plate, the first arc plate and the second arc plate;

[0037] The connecting plate facilitates the determination of the positions of the guide plate, the first arc plate, and the second arc plate, avoiding wear and contamination caused by rotating them during stirring, thus helping to reduce interference with the reaction.

[0038] Preferably, the stirring rod further includes:

[0039] The inner cavity is formed inside the stirring rod;

[0040] A first rubber stopper is installed through the end of the stirring rod;

[0041] The second rubber stopper is fixed inside the inner cavity, forming a buffer space with the first rubber stopper;

[0042] A partition plate, T-shaped, is fixed inside the inner cavity, dividing the inner cavity into a storage space, a liquid flow space, and an air flushing space, which are distinct from the buffer space.

[0043] Two third rubber plugs are installed through the side wall of the partition plate, respectively connecting the storage space with the liquid flow space and the air flushing space;

[0044] A magnetic sliding cover is slidably fitted onto the outside of the stirring rod and is adjusted by magnetic drive on the outer wall of the stirring rod.

[0045] A circular hole is formed on the side wall of the buffer space, and the magnetic sliding cover covers the circular hole;

[0046] A conveying assembly is installed between the stirring rod and the reactor and the second rotating shaft, or between the stirring rod and the reactor and the first rotating shaft, for connecting an external raw material pump to convey raw materials;

[0047] After the conveying component delivers the acid or alkali solution into the liquid flow space, it breaks through the third rubber stopper and enters the storage space under the action of the conveying pressure. This allows for the quantitative delivery of the acid or alkali solution into the storage space. Subsequently, airflow is delivered into the air purging space. Under the action of the airflow, the acid or alkali solution in the storage space can be delivered into the buffer space. Through the action of the airflow, the acid or alkali solution can be fully delivered into the reactor, which helps to avoid the generation of residues and improves the accuracy of pH adjustment.

[0048] After one delivery is completed, control the magnetic sliding cover to move so that the magnetic sliding cover moves to expose the round hole, so that the reactants can carry away the acid or alkali inside the buffer space through the round hole during the stirring process, so as to achieve thorough mixing.

[0049] The first, second, and third rubber stoppers are all rubber stoppers that are sealed under normal pressure but develop an opening at the center when subjected to impact under high pressure.

[0050] Preferably, the conveying assembly includes:

[0051] The first connecting pipe has one end connected to the liquid flow space;

[0052] The second connecting pipe is connected at one end to the air-purging space;

[0053] Two inner tanks are both opened inside the second rotating shaft or the first rotating shaft, and the second rotating shaft passes through the bottom of the reactor. The two inner tanks are independently connected to the first connecting pipe and the second connecting pipe, respectively.

[0054] The connecting box has two independent built-in spaces, which are fixed to the bottom or inside of the reactor and are rotatably and sealingly connected to the second rotating shaft or the first rotating shaft.

[0055] Two sets of openings are arranged in a circular array and are respectively opened through the outer wall of the inner groove and the inner wall of the connecting box, so as to maintain the communication between the connecting box and the inner groove when the second rotating shaft or the first rotating shaft rotates.

[0056] Two third connecting pipes are respectively connected to the two built-in spaces inside the connecting box;

[0057] The acid or alkali solution is called the conditioning liquid. When the conditioning liquid is delivered to the inside of the connecting box, the connecting box and the inner tank can still be maintained when the second rotating shaft rotates. This allows the conditioning liquid to pass through the inner tank and enter the liquid flow space through the first connecting pipe, thus enabling the delivery of the conditioning liquid. Similarly, the airflow can be delivered to the air-impact space to achieve air-impact delivery.

[0058] Preferably, it further includes:

[0059] The control unit is installed inside the reactor.

[0060] The control unit is used to control the delivery assembly to start when the pH detector detects a pH deviation in the reactor, so as to quantitatively deliver acid or alkali solution to adjust the pH inside the reactor.

[0061] A pH meter installed inside the reactor collects the pH signal of the solution in real time and transmits it to the control unit. When the detected value deviates from the preset process threshold (such as 5.0-5.5 for manganese removal by oxidation or 5.0-6.0 for calcium removal by fluorination), the control unit immediately calculates the required amount of acid or alkali based on the deviation and precisely activates the delivery components to automatically add acid or alkali solution quantitatively to the reactor, such as the fixed stroke of a peristaltic pump or the set flow rate of a metering pump, until the pH returns to the set range. This process requires no manual intervention, is rapid in response, and is precise in addition, which helps to avoid the problems of lag, over-addition, or under-addition that often occur with manual adjustment. This ensures that the pH of the reaction system is always stable in the optimal range, thereby ensuring that Mn²⁺ is completely oxidized to MnO2 precipitate and Ca²⁺ is fully converted to CaF2 precipitate, while minimizing the co-precipitation loss of Li⁺, significantly improving the lithium recovery rate. Furthermore, automated quantitative control reduces the waste of acid and alkali reagents, lowers production costs, and the stable pH environment helps to form precipitates with uniform particle size and good filtration performance, improving the efficiency of subsequent solid-liquid separation.

[0062] Preferably, it further includes:

[0063] The control unit is also configured to subsequently control the magnetic sliding cover to move and expose the circular hole after each activation of the conveying assembly;

[0064] The control unit is electrically connected to the electromagnetic drive device. When the conveying component has finished adding acid, alkali or precipitant into the reactor, the control unit issues an opening command, causing the magnetic sliding cover to move directionally along the guide rail or chute under the action of magnetic force, thereby exposing the pre-closed round hole. This allows the round hole to be exposed after the addition is completed, and the flow of reactants can carry the residual acid, alkali or precipitant through the round hole.

[0065] Compared with the prior art, the present invention has the following beneficial effects:

[0066] The automated pH and temperature control system avoids lithium loss caused by manganese and calcium co-precipitation in traditional processes, enabling a comprehensive lithium recovery rate of over 90%. The fluorination calcium removal process can reduce calcium impurities to battery-grade standards, which helps solve the problem of deep decalcification that is difficult to achieve with conventional carbonate methods. At the same time, the separation and adjustment device realizes clean transfer and online monitoring between each step, reducing human operation errors and cross-contamination. Attached Figure Description

[0067] Figure 1 This is a schematic diagram of the method flow of the present invention.

[0068] Figure 2 This is a schematic diagram of the overall structure of the separation and adjustment device of the present invention.

[0069] Figure 3This is a schematic diagram of the cross-section of the separation and adjustment device of the present invention. Figure 1 .

[0070] Figure 4 For the present invention Figure 3 A magnified structural diagram of point A in the middle.

[0071] Figure 5 For the present invention Figure 3 A magnified structural diagram at point B in the middle.

[0072] Figure 6 For the present invention Figure 3 A magnified structural diagram at point E in the middle.

[0073] Figure 7 This is a schematic diagram of the cross-section of the separation and adjustment device of the present invention. Figure 2 .

[0074] Figure 8 For the present invention Figure 7 A magnified structural diagram at point C.

[0075] Figure 9 For the present invention Figure 7 A magnified structural diagram at point D.

[0076] In the diagram: 1. Reactor; 101. Sealing cap; 102. Support; 103. Motor; 104. First rotating shaft; 105. Stirring rod; 2. Second rotating shaft; 201. Rotating support base; 202. Guide plate; 203. First arc-shaped plate; 3. Box body; 301. Box cover; 302. First gear; 303. Second gear; 304. Third gear; 305. Fourth gear; 306. First connecting rod; 307. Second connecting rod; 308. Support rod; 4. Second arc-shaped plate; 5. Connecting plate; 601. First rubber stopper; 602. Second rubber stopper; 603. Divider plate; 604. Third rubber stopper; 605. Magnetic sliding cap; 701. First connecting pipe; 702. Second connecting pipe; 703. Inner groove; 704. Connecting box; 705. Opening; 706. Third connecting pipe. Detailed Implementation

[0077] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0078] like Figures 1 to 9 The method for deep impurity removal of manganese and calcium in the lithium extraction process of lithium manganese oxide waste, as shown, includes the following steps:

[0079] Step 1, Reduction Acid Leaching: Lithium manganese oxide waste is mixed with sulfuric acid and hydrogen peroxide in a separation and regulation device to carry out a leaching reaction, resulting in a leachate containing Li⁺, Mn²⁺, and Ca²⁺.

[0080] Step 2, Oxidation to remove manganese: The pH of the leachate is monitored and adjusted to 5.0-5.5 using a separation and adjustment device. An oxidant is added to oxidize Mn²⁺ to MnO₂ precipitate. MnO₂ is removed by filtration to obtain a purified solution containing Li⁺ and Ca²⁺.

[0081] Step 3, Deep Calcium Removal by Fluorination: Transfer the purified solution to a clean separation and adjustment device, adjust the pH of the purified solution to 5.0-6.0 using the separation and adjustment device, add fluorinating agent, heat and stir to react and generate CaF2 precipitate, filter to remove CaF2, and obtain lithium-containing purified solution, in which the Ca²⁺ concentration is less than 10 ppm;

[0082] Step 4, Lithium precipitation: Add saturated sodium carbonate solution to lithium-containing refined solution, heat to precipitate and obtain battery-grade lithium carbonate product;

[0083] In the prior art, when controlling pH during the lithium extraction process, the presence of a large amount of solution in the process leads to different pH values ​​at different locations and heights inside the reactor. This results in unstable pH adjustment during the reaction process, causing different reaction degrees and thus affecting the lithium extraction effect.

[0084] This embodiment of the invention solves the above problems. The specific implementation is as follows: Utilizing the differences in the chemical properties of manganese, calcium, and lithium, a separation and adjustment device precisely controls the pH, temperature, and feeding conditions at each step to achieve stepwise selective precipitation and deep impurity removal. First, in the reduction acid leaching stage, sulfuric acid and hydrogen peroxide synergistically dissolve lithium, manganese, and calcium in the waste in ionic form simultaneously. Hydrogen peroxide, as a reducing agent, promotes the leaching of manganese. Subsequently, in the oxidation manganese removal stage, the separation and adjustment device automatically stabilizes the pH at 5.0-5.5 and adds ammonium persulfate or ozone. Taking advantage of the characteristic that Mn²⁺ is easily oxidized to MnO₂ precipitate under heating conditions, manganese is separated in the form of high-purity manganese slag, while lithium and calcium remain in the solution. Next, in the fluorination deep calcium removal stage, the separation and adjustment device precisely adjusts the pH to 5.0-6.0 and adds manganese fluoride or sodium fluoride. Based on the extremely low solubility product of CaF₂, calcium ions are preferentially precipitated as calcium fluoride, while lithium ions are almost not lost due to the relatively high solubility of lithium fluoride, thereby removing calcium to a depth of 10. Below ppm, saturated sodium carbonate is added in the final lithium precipitation stage to obtain battery-grade lithium carbonate products. The automated pH and temperature control system avoids lithium loss caused by manganese and calcium co-precipitation in traditional processes, enabling a comprehensive lithium recovery rate of over 90%. The fluorination calcium removal process can reduce calcium impurities to battery-grade standards, which helps solve the problem of deep decalcification that is difficult to achieve with conventional carbonate methods. At the same time, the separation and adjustment device realizes clean transfer and online monitoring between each step, reducing human operation errors and cross-contamination.

[0085] As an optional embodiment, the separation adjustment device includes:

[0086] The reactor 1 has a detachable and fixed sealing cover 101 on its top and a bracket 102 fixed at its bottom.

[0087] Motor 103 is fixed to the top of sealing cover 101;

[0088] The first rotating shaft 104 is rotatably mounted on the bottom of the sealing cover 101 and located inside the reactor 1. The motor 103 drives the first rotating shaft 104 to rotate through the output shaft.

[0089] Multiple stirring rods 105 are installed on the outer wall of the first rotating shaft 104, and a pH meter is installed at the end of each stirring rod 105.

[0090] The variable speed drive assembly is installed between the first rotating shaft 104 and the reactor 1. It drives the internal liquid to flow longitudinally along the interior of the reactor 1 through the speed difference to achieve uniform stirring.

[0091] When adjusting the pH of the reactants inside the reactor 1, the motor 103 drives the first rotating shaft 104 connected to it to rotate via the output shaft. The first rotating shaft 104 drives the stirring rod 105 to rotate, and the stirring rod 105 stirs the reactants. At the same time, the pH of the reactants after uniform stirring is monitored by a pH detector at the end, which helps to improve the accuracy of pH detection. When a pH deviation is detected, acid or alkali solution is slowly added into the reactor 1 while stirring via the stirring rod 105. This helps to slowly adjust the acid or alkali during stirring, thus avoiding local pH changes that may affect the reaction effect. Furthermore, the variable speed drive component can automatically drive the reactants to achieve vertical flow and stirring inside the reactor 1, thereby further increasing the uniformity of the reactants, making the internal pH uniform and accurately adjusted, and improving the reaction effect.

[0092] Preferably, the transmission drive assembly includes:

[0093] The second rotating shaft 2 is rotatably installed inside the reactor 1;

[0094] Rotate the support base 201, which is fixed to the bottom of the second rotating shaft 2 and rotatably installed at the bottom of the inside of the reactor 1;

[0095] The first arc-shaped plate 203 is detachably installed inside the reactor 1;

[0096] The guide plate 202 is fixed above the first arc plate 203 by a connecting frame and is located inside the reactor 1, forming a liquid flow guiding path with the first arc plate 203;

[0097] The speed-changing component is installed between the first rotating shaft 104 and the second rotating shaft 2. It drives the second rotating shaft 2 by accelerating the rotation, so as to drive the liquid flow toward the first arc plate 203 to form a liquid flow along the guide path.

[0098] After the first rotating shaft 104 rotates, it drives the stirring rod 105 on the second rotating shaft 2 to rotate at high speed through the speed-changing component. The stirring rod 105 rotates at high speed in some areas, and at the same time, the high-speed rotating stirring rod 105 aligns with the first arc plate 203, which increases the centrifugal force of the local reactants. The increased centrifugal force causes the local reactants to impact the first arc plate 203. Under the guidance of the first arc plate 203, the reactants flow upward along the guide plate 202. After being guided upward by the guide plate 202, the reactants reach the top of the reactants along the top of the guide plate 202, thereby guiding the flow path of the reactants, which helps to improve the uniformity of the reactants and thus improve the uniform adjustment effect of pH.

[0099] Preferably, the transmission component includes:

[0100] The box body 3 is rotatably mounted on the top of the second rotating shaft 2, and its edge is fixedly connected to the guide plate 202 via the support rod 308;

[0101] The cover 301 is rotatably mounted on the bottom of the first rotating shaft 104;

[0102] The first gear 302 is rotatably installed inside the housing 3 and is connected to the first rotating shaft 104 by the first plug-in rod 306.

[0103] The fourth gear 305 is rotatably mounted inside the housing 3 and is connected to the second rotating shaft 2 via the second insertion rod 307;

[0104] The second gear 303 and the third gear 304 are coaxially rotatably mounted inside the housing 3, and the first gear 302 meshes with the second gear 303, the fourth gear 305 meshes with the third gear 304, and the diameter of the first gear 302 and the fourth gear 305 is larger than the diameter of the second gear 303 and the fourth gear 305.

[0105] After the first rotating shaft 104 is installed, the first insertion rod 306 at the bottom of the first rotating shaft 104 is inserted and connected to the first gear 302, so that the first gear 302 can be rotated after rotation. The first gear 302 drives the second gear 303 to rotate, the second gear 303 drives the third gear 304 to rotate, and the third gear 304 drives the fourth gear 305 meshing with it to rotate. The bottom of the fourth gear 305 is inserted and connected to the second rotating shaft 2 through the second insertion rod 307 to drive the second rotating shaft 2 to rotate. At the same time, by setting the diameter ratio of the first gear 302, the second gear 303, the third gear 304, and the fourth gear 305, the rotation speed of the second rotating shaft 2 can be increased, thereby driving the stirring rod 105 on the second rotating shaft 2 to rotate at high speed and causing the reactants to flow vertically.

[0106] Preferably, the transmission drive assembly further includes:

[0107] The second arc-shaped plate 4 is installed inside the reactor 1, with the center of the groove aligned with the top of the guide plate 202 and a gap left.

[0108] The second arc-shaped plate 4 is designed so that after the reactants are guided upward by the guide plate 202, they are guided downward by the arc shape of the second arc-shaped plate 4, thereby further increasing the circulation of the reactants and improving the uniformity.

[0109] Preferably, the transmission drive assembly further includes:

[0110] Two connecting plates 5 are symmetrically inserted into the grooves opened on the inner wall of the reactor 1, and their side walls are fixedly connected to the guide plate 202, the first arc plate 203 and the second arc plate 4 respectively.

[0111] The connection plate 5 facilitates the determination of the positions of the guide plate 202, the first arc plate 203, and the second arc plate 4, avoiding wear and contamination caused by rotating them during stirring, thus helping to reduce interference with the reaction.

[0112] Preferably, the stirring rod 105 further includes:

[0113] The inner cavity is located inside the stirring rod 105;

[0114] The first rubber stopper 601 is installed through the end of the stirring rod 105;

[0115] The second rubber stopper 602 is fixed inside the inner cavity, forming a buffer space with the first rubber stopper 601;

[0116] The partition plate 603, T-shaped, is fixed inside the cavity and divides the cavity into a storage space, a liquid flow space, and an air blasting space, which are distinct from the buffer space.

[0117] Two third rubber plugs 604 are installed through the side wall of the partition plate 603, respectively connecting the storage space with the liquid flow space and the air flushing space;

[0118] A magnetic sliding cover 605 is slidably sleeved on the outside of the stirring rod 105 and is adjusted by magnetic drive on the outer wall of the stirring rod 105.

[0119] A round hole is formed on the side wall of the buffer space, and a magnetic sliding cover 605 covers the round hole;

[0120] The conveying assembly is installed between the stirring rod 105 and the reactor 1 and the second rotating shaft 2, or between the stirring rod 105 and the reactor 1 and the first rotating shaft 104, and is used to connect an external raw material pump for conveying raw materials.

[0121] After the conveying component delivers the acid or alkali solution into the liquid flow space, it breaks through the third rubber stopper 604 and enters the storage space under the action of the conveying pressure. This allows for the quantitative delivery of the acid or alkali solution into the storage space. Subsequently, airflow is delivered into the air purging space. Under the action of the airflow, the acid or alkali solution in the storage space can be delivered into the buffer space. Through the action of the airflow, the acid or alkali solution can be fully delivered into the reactor 1, which helps to avoid the generation of residue and improves the accuracy of pH adjustment.

[0122] After one delivery is completed, control the magnetic sliding cover 605 to move so that the magnetic sliding cover 605 moves to expose the round hole, so that the reactants can carry away the acid or alkali inside the buffer space through the round hole during the stirring process, so as to achieve full mixing.

[0123] The first rubber stopper 601, the second rubber stopper 602, and the third rubber stopper 604 are all rubber stoppers that are sealed under normal pressure but open at the center when subjected to impact under high pressure.

[0124] Preferably, the conveying assembly includes:

[0125] The first connecting pipe 701 is connected at one end to the liquid flow space;

[0126] The second connecting pipe 702 is connected at one end to the air-purging space;

[0127] Both inner tanks 703 are opened inside the second rotating shaft 2 or the first rotating shaft 104, and the second rotating shaft 2 passes through the bottom of the reactor 1. The two inner tanks 703 are independently connected to the first connecting pipe 701 and the second connecting pipe 702 respectively.

[0128] The connecting box 704 has two independent built-in spaces, which are fixed to the bottom or inside of the reactor 1 and are rotatably and sealingly connected to the second rotating shaft 2 or the first rotating shaft 104.

[0129] Two sets of openings 705 are arranged in a circular array and are respectively opened through the outer wall of the inner groove 703 and the inner wall of the first-level connecting box 704, so as to maintain the connection between the connecting box 704 and the inner groove 703 when the second rotating shaft 2 or the first rotating shaft 104 rotates.

[0130] Two third connecting pipes 706 connect to two internal spaces inside the connecting box 704, respectively;

[0131] The acid or alkali solution is called the conditioning liquid. When the conditioning liquid is delivered to the inside of the connecting box 704, the connecting box 704 and the inner tank 703 can still be maintained when the second rotating shaft 2 rotates. This allows the conditioning liquid to pass through the inner tank 703 and enter the liquid flow space through the first connecting pipe 701, thus enabling the delivery of the conditioning liquid. Similarly, the airflow can be delivered to the air-impact space to achieve air-impact delivery.

[0132] Preferably, it further includes:

[0133] The control unit is installed inside reactor 1;

[0134] The control unit is used to start the delivery assembly when the pH detector detects a pH deviation in the reactor 1, so as to quantitatively deliver acid or alkali solution to adjust the pH inside the reactor 1.

[0135] A pH meter installed inside the reactor collects the pH signal of the solution in real time and transmits it to the control unit. When the detected value deviates from the preset process threshold (such as 5.0-5.5 for manganese removal by oxidation or 5.0-6.0 for calcium removal by fluorination), the control unit immediately calculates the required amount of acid or alkali based on the deviation and precisely activates the delivery components to automatically add acid or alkali solution quantitatively to the reactor, such as the fixed stroke of a peristaltic pump or the set flow rate of a metering pump, until the pH returns to the set range. This process requires no manual intervention, is rapid in response, and is precise in addition, which helps to avoid the problems of lag, over-addition, or under-addition that often occur with manual adjustment. This ensures that the pH of the reaction system is always stable in the optimal range, thereby ensuring that Mn²⁺ is completely oxidized to MnO2 precipitate and Ca²⁺ is fully converted to CaF2 precipitate, while minimizing the co-precipitation loss of Li⁺, significantly improving the lithium recovery rate. Furthermore, automated quantitative control reduces the waste of acid and alkali reagents, lowers production costs, and the stable pH environment helps to form precipitates with uniform particle size and good filtration performance, improving the efficiency of subsequent solid-liquid separation.

[0136] Preferably, it further includes:

[0137] The control unit is also used to subsequently control the magnetic sliding cover to move and expose the circular hole after each start of the delivery assembly;

[0138] The control unit is electrically connected to the electromagnetic drive device. When the conveying component has finished adding acid, alkali or precipitant into the reactor, the control unit issues an opening command, causing the magnetic sliding cover to move directionally along the guide rail or chute under the action of magnetic force, thereby exposing the pre-closed round hole. This allows the round hole to be exposed after the addition is completed, and the flow of reactants can carry the residual acid, alkali or precipitant through the round hole.

[0139] The working principle of this invention is as follows: Utilizing the differences in chemical properties among manganese, calcium, and lithium, a separation and adjustment device precisely controls the pH, temperature, and feeding conditions at each step to achieve stepwise selective precipitation and deep impurity removal. First, in the reduction acid leaching stage, sulfuric acid and hydrogen peroxide synergistically dissolve lithium, manganese, and calcium in the waste material in ionic form simultaneously. Hydrogen peroxide, acting as a reducing agent, promotes the leaching of manganese. Subsequently, in the oxidation manganese removal stage, the separation and adjustment device automatically stabilizes the pH at 5.0-5.5 and adds ammonium persulfate or ozone. Taking advantage of the characteristic that Mn²⁺ is easily oxidized to MnO₂ precipitate under heating conditions, manganese is separated as high-purity manganese slag, while lithium and calcium remain in the solution. Next, in the fluorination deep calcium removal stage, the separation and adjustment device precisely adjusts the pH to 5.0-6.0 and adds manganese fluoride or sodium fluoride. Based on the extremely low solubility product of CaF₂, calcium ions are preferentially precipitated as calcium fluoride, while lithium ions are almost not lost due to the relatively high solubility of lithium fluoride, thus achieving a calcium removal depth of 10. Below ppm, saturated sodium carbonate is added in the final lithium precipitation stage to obtain battery-grade lithium carbonate products. The automated pH and temperature control system avoids lithium loss caused by manganese and calcium co-precipitation in traditional processes, enabling a comprehensive lithium recovery rate of over 90%. The fluorination calcium removal process can reduce calcium impurities to battery-grade standards, which helps solve the problem of deep decalcification that is difficult to achieve with conventional carbonate methods. At the same time, the separation and adjustment device realizes clean transfer and online monitoring between each step, reducing human operation errors and cross-contamination.

[0140] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed invention.

Claims

1. A deep impurity removal method for efficient separation of manganese and calcium during lithium extraction from lithium manganese oxide waste, characterized in that, Includes the following steps: Step 1, Reduction Acid Leaching: Lithium manganese oxide waste is mixed with sulfuric acid and hydrogen peroxide in a separation and regulation device to carry out a leaching reaction, resulting in a leachate containing Li⁺, Mn²⁺, and Ca²⁺. Step 2, Oxidation to remove manganese: The pH of the leachate is monitored and adjusted to 5.0-5.5 using the separation and adjustment device. An oxidant is added to oxidize Mn²⁺ to MnO₂ precipitate. MnO₂ is removed by filtration to obtain a purified solution containing Li⁺ and Ca²⁺. Step 3, deep fluorination for calcium removal: The purified solution is transferred to the clean separation and adjustment device, and the pH of the purified solution is adjusted to 5.0-6.0 by the separation and adjustment device. Fluorinizing agent is added, and the mixture is heated and stirred to generate CaF2 precipitate. CaF2 is removed by filtration to obtain a lithium-containing purified solution, wherein the Ca²⁺ concentration is less than 10 ppm. Step 4, Lithium precipitation: Add saturated sodium carbonate solution to the lithium-containing refined solution, and heat to precipitate and obtain battery-grade lithium carbonate product.

2. The deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process from lithium manganese oxide waste according to claim 1, characterized in that, The separation adjustment device includes: The reactor (1) has a sealing cover (101) that can be detachably fixed on the top and a bracket (102) that is fixed on the bottom. The motor (103) is fixed to the top of the sealing cover (101); The first rotating shaft (104) is rotatably mounted on the bottom of the sealing cover (101) and located inside the reactor (1). The motor (103) drives the first rotating shaft (104) to rotate through the output shaft. Multiple stirring rods (105) are installed on the outer wall of the first rotating shaft (104), and each stirring rod (105) is equipped with a pH meter at its end; The variable speed drive assembly is installed between the first rotating shaft (104) and the reactor (1). It drives the internal liquid to flow longitudinally along the interior of the reactor (1) through the speed difference, so as to achieve uniform stirring.

3. The deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process of lithium manganese oxide waste according to claim 2, characterized in that, The variable speed drive component includes: The second rotating shaft (2) is rotatably installed inside the reactor (1); Rotary support base (201) is fixed to the bottom of the second rotating shaft (2) and rotatably installed at the bottom of the inside of the reactor (1); The first arc-shaped plate (203) is detachably installed inside the reactor (1); The guide plate (202) is fixed above the first arc plate (203) by a connecting frame and is located inside the reactor (1), forming a liquid flow guiding path with the first arc plate (203); The speed changer is installed between the first rotating shaft (104) and the second rotating shaft (2). It drives the second rotating shaft (2) by accelerating its rotation to drive the liquid flow toward the first arc plate (203) to form a liquid flow along the guide path.

4. The deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process of lithium manganese oxide waste according to claim 3, characterized in that, The transmission component includes: The box body (3) is rotatably mounted on the top of the second rotating shaft (2), and its edge is fixedly connected to the guide plate (202) by a support rod (308); The lid (301) is rotatably mounted on the bottom of the first rotating shaft (104); The first gear (302) is rotatably installed inside the box (3) and is connected to the first rotating shaft (104) by the first plug rod (306); The fourth gear (305) is rotatably installed inside the box (3) and is connected to the second rotating shaft (2) by the second plug rod (307); The second gear (303) and the third gear (304) are coaxially rotatably mounted inside the housing (3), and the first gear (302) meshes with the second gear (303), and the fourth gear (305) meshes with the third gear (304), and the diameter of the first gear (302) and the fourth gear (305) is greater than the diameter of the second gear (303) and the fourth gear (305).

5. The deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process of lithium manganese oxide waste according to claim 3, characterized in that, The variable speed drive assembly also includes: The second arc-shaped plate (4) is installed inside the reactor (1), and the center of the groove is aligned with the top of the guide plate (202) with a gap.

6. The deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process of lithium manganese oxide waste according to claim 5, characterized in that, The variable speed drive assembly also includes: Two connecting plates (5) are symmetrically inserted into the grooves opened on the inner wall of the reactor (1), and their side walls are fixedly connected to the guide plate (202), the first arc plate (203) and the second arc plate (4) respectively.

7. The deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process from lithium manganese oxide waste according to claim 6, characterized in that, The stirring rod (105) also includes: The inner cavity is formed inside the stirring rod (105); A first rubber stopper (601) is installed through the end of the stirring rod (105); The second rubber plug (602) is fixed inside the inner cavity, forming a buffer space between it and the first rubber plug (6); A partition plate (603), T-shaped, is fixed inside the inner cavity to divide the inner cavity into a storage space, a liquid flow space, and an air flushing space, which are distinct from the buffer space. Two third rubber plugs (604) are installed through the side wall of the partition plate (603) and respectively connect the storage space with the liquid flow space and the air flushing space; A magnetic sliding cover (605) is slidably sleeved on the outside of the stirring rod (105) and is adjusted by magnetic drive on the outer wall of the stirring rod (105); A circular hole is formed on the side wall of the buffer space, and the magnetic sliding cover (605) covers the circular hole; The conveying assembly is installed between the stirring rod (105) and the reactor (1) and the second rotating shaft (2) or between the stirring rod (105) and the reactor (1) and the first rotating shaft (104), and is used to connect an external raw material pump for conveying raw materials.

8. The deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process from lithium manganese oxide waste according to claim 7, characterized in that, The conveying assembly includes: The first connecting pipe (701) is connected at one end to the liquid flow space; The second connecting pipe (702) is connected at one end to the air-filled space; Two inner tanks (703) are both opened inside the second rotating shaft (2) or the first rotating shaft (104), and the second rotating shaft (2) passes through the bottom of the reactor (1). The two inner tanks (703) are independently connected to the first connecting pipe (701) and the second connecting pipe (702). The connecting box (704) has two independent built-in spaces, which are fixed to the bottom or inside of the reactor (1) and are rotatably and sealed to the second rotating shaft (2) or the first rotating shaft (104); Two sets of openings (705) are arranged in a circular array and are respectively opened through the outer wall of the inner groove (703) and the inner wall of the connecting box (704) to maintain the communication between the connecting box (704) and the inner groove (703) when the second rotating shaft (2) or the first rotating shaft (104) rotates. Two third connecting pipes (706) are respectively connected to the two built-in spaces inside the connecting box (704).

9. A deep impurity removal method for efficient separation of manganese and calcium in the lithium extraction process from lithium manganese oxide waste, as described in claim 8, is characterized in that... Also includes: The control unit is installed inside the reactor (1); The control unit is used to control the delivery assembly to start when the pH detector detects that the pH of the reactor (1) deviates, so as to quantitatively deliver acid or alkali solution to adjust the pH inside the reactor (1).

10. A deep impurity removal method for efficient separation of manganese and calcium during lithium extraction from lithium manganese oxide waste, as described in claim 9, is characterized in that... Also includes: The control unit is also configured to subsequently control the magnetic sliding cover (605) to move and expose the circular hole after each activation of the delivery assembly.

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