Impurity removal and purification method for iron oxide powder material for lithium ion battery

Abstract

The invention discloses an impurity removal and purification method for an iron oxide powder material for a lithium ion battery, which is characterized in that the iron oxide powder material for the lithium ion battery is raised upwards and scattered downwards in a temperature field, so that the scattered powder material is impacted by sprayed protective gas flow; and gas impurities separated out from the surface of the powder material are taken away by the protective gas flow and are sucked and discharged to realize impurity removal and purification. According to the method, impurities generated on the basis of harmful gas adhesion in the iron oxide powder material for the battery can be removed more quickly, efficiently and reliably, the heat purification efficiency and effect are better improved, and high purity and performance consistency of the iron oxide powder are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery manufacturing technology, specifically to a method for removing impurities and purifying iron oxide powder materials for lithium-ion batteries. Background Technology

[0002] In the field of lithium-ion battery technology, iron oxide, as a key material in the process of preparing lithium iron phosphate from iron oxide red, can optimize the performance of lithium iron phosphate cathodes by precisely controlling its physicochemical properties (such as tap density and impurity content), ultimately achieving the preparation of high-performance lithium iron phosphate cathode materials. In recent years, the continuous expansion of my country's steel industry and the steady growth of social steel reserves have provided ample raw material support for the low-cost preparation of iron oxide. Using industrial byproducts such as recycled pickling solutions from waste steel and waste pickling solutions from new steel as raw materials, and through multi-stage impurity removal via chemical precipitation, ion exchange, and solution extraction, followed by heating and calcination to prepare iron oxide powder, has become an important pathway to obtain high-quality iron oxide. This process not only realizes the resource utilization of industrial waste but also aligns with the guidance of green and low-carbon development, further reducing the preparation cost of iron oxide.

[0003] The particle size and morphology of iron oxide powder directly determine its electrochemical performance. Spherical powders, due to their superior flowability, dispersibility, and process adaptability, can improve electrode sheet forming quality and battery performance. Therefore, preparing high-purity, high-performance, and consistent spherical iron oxide powder is a core direction for optimizing its electrochemical performance. Currently, spray heating treatment-solid-state sintering is one of the efficient and low-cost preparation processes for this powder. Through four steps—preliminary purification, deep impurity removal, atomization into spheres, and controlled calcination—particle size control and morphological regularity can be achieved, simultaneously reducing impurities, defects, and improving density and stability. The applicant has filed patent CN202210491655.8, disclosing a granulation and impurity removal method for spherical iron oxide lithium-ion battery anode materials, laying the foundation for subsequent powder purification and performance optimization. However, this method is mainly used for the separation and removal of the iron(III) oxide portion from spherical iron oxide powder materials. However, lithium-ion batteries have stringent requirements for the purity of electrode materials. For iron oxide powder derived from the spray pyrolysis of pickling solutions from waste steel, it is still affected by three types of gaseous impurities: firstly, acidic gases remaining in the pickling waste liquid. Firstly, it is easily physically adsorbed onto the powder surface; secondly, it is the nitrogen / carbon-containing gas produced by the pyrolysis of acid pickling additives. Thirdly, non-metallic gases generated from raw material impurities and process side reactions. These impurities, which are easily chemically reacted with powders, can lead to porosity or non-metallic inclusions during subsequent sintering if not completely removed. This damages the electrode microstructure, accelerates battery capacity decay, reduces cycle stability, and significantly affects battery performance.

[0004] Removing harmful impurity gases from iron oxide by high-temperature heating under a protective gas atmosphere is one of the mainstream impurity gas purification methods for preparing iron oxide powder from recycled steel pickling solution. Commonly used processing equipment includes tube furnaces, box furnaces, pusher furnaces, fluidized bed dryers, and microwave sintering furnaces. However, these traditional devices still have significant technical shortcomings in removing the aforementioned impurities: First, during the processing, the powder is prone to forming local temperature gradients due to excessive packing. The outer layer of powder is overheated and its structure deteriorates, while the inner powder is underheated, making it difficult for impurities to be completely decomposed, and even inducing local side reactions to generate new impurity components. Second, the gaps between the powder particles in the packed state are narrow, making it difficult for the waste gas generated by heating and volatilization to escape effectively from the inside of the packing layer. The residual gas is prone to forming pores inside and between the powder particles, directly causing a decrease in the density of the subsequent electrode material. Third, the protective gas is difficult to penetrate the dense structure of the powder packing layer and penetrate evenly into the interior, causing some areas to undergo insufficient oxidation or reduction due to lack of effective protection, further deteriorating the performance consistency of the iron oxide powder and failing to meet the application requirements of lithium-ion batteries for high purity and high performance consistency of electrode materials.

[0005] This invention provides a highly efficient purification device for near-spherical iron oxide powder lithium-ion battery materials, which can achieve uniform dispersion, consistent heating and full gas-solid contact of iron oxide powder, significantly improve thermal purification efficiency and effect, ensure high purity and performance consistency of iron oxide powder, and meet the stringent requirements of near-spherical iron oxide powder in lithium-ion battery applications. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a method for removing impurities from battery iron oxide powder materials that can be removed more quickly, efficiently and reliably, so as to better improve the thermal purification efficiency and effect and ensure the high purity and performance consistency of iron oxide powder.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for removing impurities from iron oxide powder material for lithium-ion batteries is characterized in that the iron oxide powder material for lithium-ion batteries is thrown upwards and then scattered downwards in a temperature field, so that the scattered powder material is impacted by the sprayed protective gas flow. The protective gas flow carries away the gaseous impurities precipitated on the surface of the powder material, and the impurities are then drawn off and discharged to achieve purification.

[0009] In this scheme, the impact of a protective gas in a temperature field disperses the falling lithium-ion battery powder material, ensuring it is heated evenly and thoroughly. This allows surface gaseous impurities to rapidly precipitate and be drawn away by the protective gas impact. Therefore, this method achieves uniform dispersion and consistent heating of the iron oxide powder, improves gas-solid contact, significantly enhances thermal purification efficiency and effectiveness, and ensures high purity and consistent performance of the iron oxide powder, meeting the stringent requirements for spherical iron oxide powder in lithium-ion battery applications.

[0010] Furthermore, the protective gas is nitrogen or argon.

[0011] This is based on the inert chemical properties of nitrogen and argon: neither reacts chemically with the iron oxide powder used in lithium-ion batteries or the impurities to be removed. They can form a stable inert atmosphere within the powder purification system, preventing the intrusion of oxidizing gases such as oxygen and carbon dioxide from the outside air, thus avoiding oxidation and deterioration of the powder or the introduction of new impurities. At the same time, nitrogen and argon have excellent gas flowability and can be used as impurity carrier gases. Through airflow disturbance and directional transport, they can efficiently remove various harmful components desorbed from the powder surface, significantly improving the impurity removal efficiency and better achieving impurity removal and purification.

[0012] Furthermore, the temperature of the temperature field is controlled within the range of 500℃-800℃.

[0013] This is because the temperature range has been specifically optimized to achieve the synergistic and efficient removal of multiple types of impurities: for For acidic gases, temperatures of 500℃-800℃ can significantly increase their molecular kinetic energy and volatility, prompting them to rapidly detach from the physical adsorption sites on the powder surface. For adsorbed water on the powder surface, high temperatures can break the hydrogen bonds between water molecules and the powder surface, allowing them to pass through... The reaction completes the desorption; for the organic components formed by the residue of pickling additives. This temperature range can meet the requirements of its pyrolysis reaction, through The reaction converts it into gaseous products for excretion; for alkali metal impurities such as sodium and potassium... Although this temperature did not reach its decomposition temperature However, it can significantly increase its vapor pressure, causing it to precipitate from the powder in gaseous form. In summary, a temperature range of 500℃-800℃ can efficiently precipitate harmful components such as acidic gases, adsorbed water, organic residues, and alkali metal impurities under high temperature, and carry them out of the system through nitrogen or argon carrier gas, thus achieving deep purification of iron oxide powder.

[0014] Furthermore, this method relies on a continuous purification device for iron oxide powder materials used in lithium-ion batteries. This device includes a base, with a cylindrical outer shell fixedly mounted on top of the base. A heating device for inward heating is installed on the outer shell. A cylindrical rotating sleeve is rotatably and coaxially mounted inside the outer shell. Sealing structures are provided between the two ends of the rotating sleeve and the outer shell. Multiple inwardly protruding lifting plates are evenly distributed circumferentially inside the rotating sleeve, and the lifting plates are spirally shaped along the length of the rotating sleeve. An air-blowing purification device is also installed inside the rotating sleeve, comprising an air-blowing device and an air-extraction device. The air-blowing device includes an air-blowing pipe disposed within the rotating sleeve along its length and with its end relatively fixed to the outer shell. The air-blowing pipe has an air outlet. The air inlet end of the air-blowing pipe extends axially out of the rotating sleeve and is connected to a protective air source device. An external feed pipe is also connected to the feed end of the rotating sleeve, and a discharge channel is connected downwards to the discharge end of the rotating sleeve.

[0015] In this way, when the above-mentioned equipment is in use, the heating device on the outer shell heats the interior, creating a temperature field within the required temperature range inside the rotating sleeve. Then, the lithium-ion battery iron oxide powder to be purified enters the feed end of the rotating sleeve through the feed pipe. The rotating sleeve is then started to rotate, and the rotating lifting plates continuously lift the powder from below to above, then lift it again and let it fall. During this repeated lifting and falling process, the powder comes into contact with and is impacted by the protective gas blown out from the air pipe. This causes impurities that have precipitated on the powder surface under the temperature field to detach from the powder and be carried away by the suction device, thus achieving purification. Because the lifting plates are spirally arranged along their length, the powder gradually moves towards the discharge end during this repeated lifting and falling process. Finally, the purified powder exits from the discharge channel.

[0016] Furthermore, the heating device is an electric heating device, which facilitates control.

[0017] Furthermore, both ends of the air blowing pipe are respectively fixed on a vertically oriented disc-shaped fixed support base. The outer middle of the fixed support base has a cylindrical connecting part arranged coaxially outward and fixedly connected to the base. The feeding end of the rotating sleeve has an end plate located on the outer side of the fixed support base at this end. A cylindrical transmission part is coaxially fixed outward in the middle of the end plate. The transmission part is rotatably sleeved on the connecting part on the outer side of the fixed support base at this end and is used for driving connection with a rotating motor. There is a gap space between the discharge end of the rotating sleeve and the inner side of the fixed support base at this end for setting a discharge channel below. The feeding pipe passes through and is fixed on the fixed support base at the feeding end, and its outer end protrudes outward from the connecting part on the outer side of the fixed support base and is used to connect to the feeding device. The air inlet end of the air blowing pipe protrudes outward from the connecting part of the fixed support base at the discharge end and is connected to a protective air source device.

[0018] This facilitates the installation and transmission of the rotating sleeve, makes it easier to connect and install the components and avoid interference, and allows each component to perform its function better. In implementation, a screw feeder (or pneumatic input device) is preferred for the feeding device to achieve sealed and quantitative feeding. In implementation, an external rotary valve (or cyclone separator) is preferred at the lower end of the discharge channel to better achieve sealed discharge.

[0019] Furthermore, the transmission part on the outer side of the end plate of the feed end of the rotating sleeve is rotatably and sealed to the fixed support base connecting part on the inner side and the outer shell end. The fixed support base connecting part of the discharge end is sealed and fixedly connected to the shell end of that end. A bearing support is provided between the outer side of the discharge end of the rotating sleeve and the corresponding inner side of the shell.

[0020] This ensures a good seal inside the outer casing while maintaining the rotational stability of the rotating sleeve.

[0021] Furthermore, the inner end of the feed pipe extends downward into the lower inner wall of the corresponding fixed support base for feeding, and a feed hood is correspondingly provided on the side wall of the fixed support base where the inner end of the feed pipe is located, with the lower end of the feed hood being open.

[0022] This feed hood is used to block the incoming powder, causing it to fall directly into the space between the lifting plates below the feed end inside the rotating sleeve, where it is conveyed from the beginning to the end and purified.

[0023] Furthermore, the inner wall of the rotating sleeve is also provided with partitions arranged in a ring along the circumferential direction at intervals along the length direction, and the partitions are set at the same height as the lifting plate.

[0024] This better prevents the material from sliding down the spiral surface of the lifting plate when it rotates to the middle position of the side of the rotating sleeve, thus ensuring that the material can be lifted upwards. At the same time, the partition separates each lifting plate into an independent space, which can also better cooperate with the baffle chamber of the air extraction device to extract air and discharge powder.

[0025] Furthermore, the air blowing device also includes an air blowing guide housing. The air blowing guide housing is generally elongated along the length of the air blowing pipe and covers the air blowing pipe inside it. The air blowing guide housing is located at the upper part of the side in front of the rotating sleeve cavity in the rotation direction. The upper outer side of the air blowing guide housing is an arc shape that rotates with the inner end of the lifting plate. A first air outlet is provided at the upper part of the inner side of the air blowing guide housing and is connected to the air blowing pipe. An elongated impeller along the length of the air blowing pipe is rotatably installed outside the first air outlet. The air outlet can drive the upper end of the impeller to rotate outward.

[0026] In this way, when the material is driven upward by the lifting plate inside the rotating sleeve and passes the upper end of the inner side of the air blowing guide shell, the material falls downward. At the same time, the protective gas blown out by the air blowing pipe drives the upper end of the impeller to rotate outward. After the material falls, under the combined action of the airflow blown out of the first air outlet and the impeller, it can be better dispersed in the inner cavity of the rotating sleeve in a direction away from the air blowing guide shell. Under the strong action of the airflow, the impurity gas that is released from the surface of the powder under the temperature field can be better separated from the powder and enter the airflow, and then carried away by the exhaust device, thus improving the purification effect.

[0027] Furthermore, the upper end of the inner side of the air-blowing guide housing has an upper material dropping surface that slopes downward and forward. An inward diversion groove is provided on the lower side of the upper material dropping surface. The first air outlet is located in the middle of the bottom surface of the diversion groove. An arc-shaped diversion baffle, consistent with the arc of the bottom surface of the groove, is also provided at intervals outside the first air outlet in the diversion groove. The impeller is installed on the outside of the diversion baffle, and the upper end of the impeller extends upward beyond the upper end of the diversion baffle along its own arc. The lower end of the impeller is located above the lower end of the diversion baffle along its own arc. The lower side of the diversion groove extends outward and downward to form a lower material dropping surface. A second air outlet that blows downward is provided at the lower end of the lower material dropping surface and is connected to the air-blowing pipe.

[0028] In this way, after the material falls from the upper inner side of the air-guiding shell, it first slides downwards onto the upper material drop surface, which helps to better disperse the material. Then, it falls onto the upper outer side of the impeller and is dispersed and blown outwards. The airflow from the first air outlet is divided into two paths by the diversion baffle. One path blows upwards and drives the impeller to rotate, serving as the main airflow factor in the purification chamber outside the impeller. The other path blows downwards, and part of the airflow directly enters the middle of the purification chamber (this effect can be further achieved by setting several protruding flow-lifting blocks at intervals along the length of the device at the junction of the lower material drop surface and the diversion groove), greatly enhancing the airflow turbulence effect in the middle of the purification chamber, allowing the protective gas airflow to better collide with the powder, thereby improving the purification effect of the airflow. Another part of the airflow in the next path can move downwards along the lower material drop surface, carrying away the purified powder that falls onto the lower material drop surface. Under the combined action of the airflow from the second air outlet, the powder falls onto the rotating sleeve below, entering the next rotation cycle. Therefore, this structure greatly improves the purification effect of airflow on powder and can better guide the powder to move along the required path.

[0029] Furthermore, the first and second air outlets are evenly arranged along the length of the air blowing pipe.

[0030] Furthermore, the air extraction device includes an air extraction pipe disposed within the rotating sleeve along its length and with its end fixed relative to the outer shell. The air extraction pipe is provided with an air extraction hole, and a porous filter material is disposed at the air extraction hole. The air outlet end of the air extraction pipe passes through the rotating sleeve axially and is connected to an external exhaust fan.

[0031] In this way, using an extraction pipe that is parallel to the air blowing pipe at intervals allows for better matching of the gas blown out by the air blowing pipe to achieve extraction and exhaust. In practice, the air outlet end of the extraction pipe extends outward through the connection part of the fixed support base at the discharge end and is connected to an external exhaust fan.

[0032] As an optimized structure, the air extraction device further includes an air extraction guide housing that is integrally arranged along the length of the air extraction pipe. The air extraction pipes are multiple pipes arranged in parallel and are enclosed within the air extraction guide housing. The air extraction guide housing is located on the other side of the blowing guide housing inside the rotating sleeve, and its outer upper side is an arc shape that rotates with the inner end of the lifting plate. A purification chamber is formed between the upper part of the inner side of the air extraction guide housing and the inner side of the blowing guide housing. The lower end of the air extraction guide housing is provided with an upward air extraction groove corresponding to each air extraction pipe, and a porous filter material is provided at the bottom of the air extraction groove and connected to the air extraction hole of the corresponding air extraction pipe.

[0033] This is because the extraction pipe needs to have a thicker powder filter structure to prevent the powder from being carried away by the airflow, which results in lower extraction efficiency. Therefore, setting up multiple extraction pipes can better match the blowing rate of the blowing pipe and achieve better treatment results.

[0034] As another optimized structure, the air extraction device also includes an air extraction guide housing. The air extraction guide housing is generally elongated along the length of the air extraction pipe and covers the air extraction pipe inside it. The air extraction guide housing is located on the other side of the blowing guide housing inside the rotating sleeve, and its outer upper side is an arc shape that rotates with the inner end of the lifting plate. A purification chamber is formed between the upper part of the inner side of the air extraction guide housing and the inner side of the blowing guide housing. The lower part of the inner side of the air extraction guide housing has an extension baffle that extends outward and downward, and a powder filter structure and an air extraction hole are connected on the rear side of the extension baffle.

[0035] In this way, the air extraction guide housing better guides the movement of powder and airflow, allowing the powder to fall into the lower front part of the rotating sleeve's inner cavity under the combined action of the airflow from the second air outlet of the blowing device and the extended baffle of the extraction device, moving in the direction of the rotating sleeve's rotation. Meanwhile, the airflow, after passing downwards over the extended baffle, flows upwards from behind the baffle and through the powder filtering structure before entering the extraction pipe through the extraction port and being discharged externally, thus better assisting in the separation of airflow and powder.

[0036] Furthermore, the suction pipe is located at the upper end of the suction guide housing. The powder filtration structure includes a porous filter material located outside the suction hole, and a guide sedimentation chamber located below the porous filter material and arranged downwards. Parallel baffles are alternately arranged on the left and right sides of the guide sedimentation chamber. The outer side of each baffle is inclined downwards to form several parallel and outwardly inclined baffle chambers. A material leakage hole is opened at the lower outer end of each baffle chamber.

[0037] In this way, when the airflow enters the guide sedimentation chamber after passing the extended baffle at the lower end of the exhaust guide housing, it will be mixed with some powder. The powder and airflow are sequentially deflected by each baffle chamber and then rise to the porous filter material. During this process, due to the rotation of the rotating sleeve, the relatively sealed space formed between each lifting plate on the rotating sleeve and the outer side of the exhaust guide housing passes sequentially through the material leakage holes at the lower outer ends of each baffle chamber. Because the suction force in the baffle chamber is relatively strong, some of the gas in the relatively sealed space passing through the material leakage holes is drawn into the baffle chamber to reduce the air pressure suction force in the baffle chamber. This gradually makes the air pressure suction force from the material leakage holes in the upper baffle chamber lower than the air pressure suction force in the relatively sealed space it passes through. Thus, the powder in the baffle chambers closer to the upper position is more likely to settle and leak downwards from the material leakage holes. Therefore, this structure not only achieves directional discharge of waste gas, but also avoids the powder being directly drawn into the ceramic filter block, causing blockage and reducing suction efficiency.

[0038] Furthermore, the suspended end of the lifting plate has a circumferentially bent section along the circle where the end is located, and the direction of the bent section is opposite to the rotation direction of the rotating sleeve.

[0039] In this way, the design of the deflection section can better improve the fit between the blowing guide shell and the suction guide shell, thus preventing airflow from entering. It also shortens the distance between adjacent lifting plates, ensuring that the inner end spacing between adjacent lifting plates is less than the distance between the material leakage holes of the uppermost and lowermost baffle chambers, making it more conducive to achieving material leakage in conjunction with the material leakage holes of the baffle chambers.

[0040] In summary, this invention can more quickly, efficiently, and reliably remove impurities from iron oxide powder materials used in batteries caused by the adhesion of harmful gases, thereby improving the efficiency and effectiveness of thermal purification and ensuring the high purity and performance consistency of iron oxide powder. Attached Figure Description

[0041] Figure 1 This is a three-dimensional structural schematic diagram of a continuous lithium-ion battery iron oxide powder material purification device used in Embodiment 1 of the present invention.

[0042] Figure 2 for Figure 1A schematic diagram of the structure after the upper half of the unicorn shell and rotating sleeve has been cut.

[0043] Figure 3 for Figure 1 A structural diagram showing the internal structure with a separate outer shell and a portion cut away.

[0044] Figure 4 for Figure 1 A schematic diagram of the structure after removing the outer shell and vertically cutting the rotating sleeve and its internal structure along the length.

[0045] Figure 5 This is a schematic diagram of the right-hand side view of the rotating sleeve and its internal structure after the outer shell has been removed and the structure has been vertically cut along the width direction.

[0046] Figure 6 for Figure 1 A structural diagram showing the internal structure with a portion cut off at the right end (discharge end).

[0047] Figure 7 This is a right sectional view of the purification equipment for iron oxide powder materials used in lithium-ion batteries, as used in Embodiment 2 of the present invention. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings.

[0049] Example 1: A method for removing impurities from iron oxide powder material for lithium-ion batteries, characterized in that the iron oxide powder material for lithium-ion batteries is thrown upwards and then scattered downwards in a temperature field, so that the scattered powder material is impacted by the sprayed protective gas flow. The protective gas flow carries away the gaseous impurities precipitated on the surface of the powder material, and the impurities are then drawn off and discharged to achieve purification.

[0050] In this scheme, the impact of a protective gas in a temperature field disperses the falling lithium-ion battery powder material, ensuring it is heated evenly and thoroughly. This allows surface gaseous impurities to rapidly precipitate and be drawn away by the protective gas impact. Therefore, this method achieves uniform dispersion and consistent heating of the iron oxide powder, improves gas-solid contact, significantly enhances thermal purification efficiency and effectiveness, and ensures high purity and consistent performance of the iron oxide powder, meeting the stringent requirements for spherical iron oxide powder in lithium-ion battery applications.

[0051] The protective gas is either nitrogen or argon.

[0052] This is based on the inert chemical properties of nitrogen and argon: neither reacts chemically with the iron oxide powder used in lithium-ion batteries or the impurities to be removed. They can form a stable inert atmosphere within the powder purification system, preventing the intrusion of oxidizing gases such as oxygen and carbon dioxide from the outside air, thus avoiding oxidation and deterioration of the powder or the introduction of new impurities. At the same time, nitrogen and argon have excellent gas flowability and can be used as impurity carrier gases. Through airflow disturbance and directional transport, they can efficiently remove various harmful components desorbed from the powder surface, significantly improving the impurity removal efficiency and better achieving impurity removal and purification.

[0053] The temperature of the temperature field is controlled within the range of 500℃-800℃.

[0054] This is because the temperature range has been specifically optimized to achieve the synergistic and efficient removal of multiple types of impurities: for For acidic gases, temperatures of 500℃-800℃ can significantly increase their molecular kinetic energy and volatility, prompting them to rapidly detach from the physical adsorption sites on the powder surface. For adsorbed water on the powder surface, high temperatures can break the hydrogen bonds between water molecules and the powder surface, allowing them to pass through... The reaction completes the desorption; for the organic components formed by the residue of pickling additives. This temperature range can meet the requirements of its pyrolysis reaction, through The reaction converts it into gaseous products and removes them; for alkali metal impurities such as sodium and potassium (e.g., NaCl), although this temperature does not reach their decomposition temperature... However, it can significantly increase its vapor pressure, causing it to precipitate from the powder in gaseous form. In summary, a temperature range of 500℃-800℃ can efficiently precipitate harmful components such as acidic gases, adsorbed water, organic residues, and alkali metal impurities under high temperature, and carry them out of the system through nitrogen or argon carrier gas, thus achieving deep purification of iron oxide powder.

[0055] In this embodiment, the method relies on a continuous lithium-ion battery iron oxide powder material purification device, see [link to documentation]. Figure 1-6As shown, the continuous lithium-ion battery iron oxide powder material purification equipment includes a base 1, a cylindrical outer shell 2 that is horizontally oriented is fixedly mounted on the base 1, a heating device 3 for inward heating is mounted on the outer shell 2, and a cylindrical rotating sleeve 4 is rotatably and coaxially mounted inside the outer shell. A sealing structure (not shown in the figure) is provided between the two ends of the rotating sleeve 4 and the outer shell. Multiple inwardly protruding lifting plates 5 are evenly distributed circumferentially inside the rotating sleeve 4. The lifting plates 5 are generally spirally oriented along the length of the rotating sleeve. An air blowing purification device is also provided inside the rotating sleeve. The air blowing purification device includes an air blowing device and an air extraction device. The air blowing device includes an air blowing pipe 6 that is disposed inside the rotating sleeve along the length of the rotating sleeve and whose end is relatively fixed to the outer shell. An air outlet is provided on the air blowing pipe 6. The air inlet end of the air blowing pipe 6 passes through the rotating sleeve axially and is connected to a protective air source device (not shown in the figure). The feed end of the rotating sleeve 4 is also connected to an external feed pipe 7, and the discharge end of the rotating sleeve 4 is connected to a discharge channel 8 downwardly.

[0056] In this way, when the above-mentioned equipment is in use, the heating device on the outer shell heats the interior, creating a temperature field within the required temperature range inside the rotating sleeve. Then, the lithium-ion battery iron oxide powder to be purified enters the feed end of the rotating sleeve through the feed pipe. The rotating sleeve is then started to rotate, and the rotating lifting plates continuously lift the powder from below to above, then lift it again and let it fall. During this repeated lifting and falling process, the powder comes into contact with and is impacted by the protective gas blown out from the air pipe. This causes impurities that have precipitated on the powder surface under the temperature field to detach from the powder and be carried away by the suction device, thus achieving purification. Because the lifting plates are spirally arranged along their length, the powder gradually moves towards the discharge end during this repeated lifting and falling process. Finally, the purified powder exits from the discharge channel.

[0057] The heating device is an electric heating device (not shown in the figure). This facilitates control.

[0058] The air blowing pipe 6 is fixed at both ends to a vertically shaped disc-shaped fixed support 9. The outer middle of the fixed support 9 has a cylindrical connecting part 10 coaxially arranged outward and fixedly connected to the base 1. The feeding end of the rotating sleeve 4 has an end plate 11 located outside the fixed support at that end. A cylindrical transmission part 12 is coaxially fixed outward in the middle of the end plate 11. The transmission part 12 is rotatably sleeved on the connecting part 10 outside the fixed support at that end and is used to drive the rotating motor. There is a gap between the discharge end of the rotating sleeve 4 and the inner side of the fixed support 9 at that end for the discharge channel 8 to be set below. The feeding pipe 7 is fixed through the fixed support at the feeding end, and its outer end protrudes outward from the connecting part outside the fixed support and is used to connect to the feeding device (not shown in the figure). The air inlet end of the air blowing pipe 6 protrudes outward from the connecting part of the fixed support at the discharge end and is connected to a protective air source device (not shown in the figure).

[0059] This facilitates the installation and transmission of the rotating sleeve, makes it easier to connect and install the components and avoid interference, and allows each component to perform its function better. In implementation, a screw feeder (or pneumatic input device) is preferred for the feeding device to achieve sealed and quantitative feeding. In implementation, an external rotary valve (or cyclone separator) is preferred at the lower end of the discharge channel to better achieve sealed discharge.

[0060] The transmission part 12 on the outer side of the end plate 11 at the feed end of the rotating sleeve 4 is rotatably and sealedly connected to the fixed support seat connection part 10 on the inner side and the outer shell end. The fixed support seat connection part at the discharge end is sealed and fixedly connected to the outer shell end at that end. A bearing (not shown in the figure) is provided between the outer side of the discharge end of the rotating sleeve and the corresponding inner side of the outer shell for support.

[0061] This ensures a good seal inside the outer casing while maintaining the rotational stability of the rotating sleeve.

[0062] The inner end of the feed pipe 7 extends downward to the lower inner wall of the corresponding fixed support base for feeding. A feed cover 14 is provided on the side wall of the fixed support base where the inner end of the feed pipe is located, and the lower end of the feed cover 14 is open.

[0063] This feed hood is used to block the incoming powder, causing it to fall directly into the space between the lifting plates below the feed end inside the rotating sleeve, where it is conveyed from the beginning to the end and purified.

[0064] The inner wall of the rotating sleeve 4 is also provided with partitions 15 arranged in a ring along the circumferential direction at intervals along the length direction. The partitions 15 and the lifting plate 5 are arranged at the same height.

[0065] This better prevents the material from sliding down the spiral surface of the lifting plate when it rotates to the middle position of the side of the rotating sleeve, thus ensuring that the material can be lifted upwards. At the same time, the partition separates each lifting plate into an independent space, which can also better cooperate with the baffle chamber of the air extraction device to extract air and discharge powder.

[0066] The air blowing device further includes an air blowing guide housing 16. The air blowing guide housing 16 is generally elongated along the length of the air blowing pipe and covers the air blowing pipe 6 inside it. The air blowing guide housing 16 is located at the upper part of the side in front of the rotation direction of the inner cavity of the rotating sleeve 4. The outer upper side of the air blowing guide housing 16 is an arc shape that rotates with the inner end of the lifting plate. A first air outlet 17 is provided at the upper part of the inner side of the air blowing guide housing 16 and is connected to the air blowing pipe. An elongated impeller 18 is rotatably installed outside the first air outlet 17 along the length of the air blowing pipe. The air coming out of the first air outlet can drive the upper end of the impeller 18 to rotate outward.

[0067] In this way, when the material is driven upward by the lifting plate inside the rotating sleeve and passes the upper end of the inner side of the air blowing guide shell, the material falls downward. At the same time, the protective gas blown out by the air blowing pipe drives the upper end of the impeller to rotate outward. After the material falls, under the combined action of the airflow blown out of the first air outlet and the impeller, it can be better dispersed in the inner cavity of the rotating sleeve in a direction away from the air blowing guide shell. Under the strong action of the airflow, the impurity gas that is released from the surface of the powder under the temperature field can be better separated from the powder and enter the airflow, and then carried away by the exhaust device, thus improving the purification effect.

[0068] The upper end of the inner side of the air-blowing guide housing 16 has an upper material drop surface 19 that slopes downward and forward. An inward diversion groove 20 is provided on the lower side of the upper material drop surface. The first air outlet 17 is located in the middle of the bottom surface of the diversion groove 20. An arc-shaped diversion baffle 21 with the same arc shape as the bottom surface of the groove is also provided at intervals inside the diversion groove 20 outside the first air outlet. The impeller 18 is installed on the outside of the diversion baffle 21, and the upper end of the impeller extends upward beyond the upper end of the diversion baffle along its own arc. The lower end of the impeller 18 is located above the lower end of the diversion baffle along its own arc. The lower side of the diversion groove 20 extends outward and downward to form a lower material drop surface 22. A second air outlet 24 with downward air outlet is provided at the lower end of the lower material drop surface 22 and is connected to the air-blowing pipe 6.

[0069] In this way, after the material falls from the upper part of the inner side of the blowing guide shell, it first falls onto the upper material dropping surface and slides downwards, which can help to better disperse the material. Then it falls onto the upper part of the impeller and is dispersed and blown outwards. The airflow blown out of the first air outlet is divided into two paths by the diversion baffle. One path blows upwards and drives the impeller to rotate, serving as the main airflow factor in the purification chamber outside the impeller. The other path blows downwards, and part of the airflow directly enters the middle of the purification chamber (in practice, several protruding flow-lifting blocks 23 are further arranged at intervals along the length of the device at the junction of the lower material dropping surface 22 and the diversion groove 20 to better achieve this effect). This greatly enhances the airflow turbulence effect in the middle of the purification chamber, allowing the protective gas airflow to better collide with the powder, thereby improving the purification effect of the airflow. Another portion of the airflow in the next path flows downwards along the material drop surface, carrying away the purified powder that falls onto the surface. Combined with the airflow from the second vent, the powder falls onto the rotating sleeve below, entering the next rotation cycle. Therefore, this structure greatly improves the purification effect of the airflow on the powder and better guides the powder to move along the desired path.

[0070] The first air outlet 17 and the second air outlet 24 are evenly arranged along the length of the air blowing pipe.

[0071] The air extraction device includes an air extraction pipe 25 disposed inside the rotating sleeve along its length and with its end fixed relative to the outer shell. The air extraction pipe 25 is provided with an air extraction hole 26, and a porous filter material 27 is provided at the air extraction hole. The air outlet end of the air extraction pipe 25 passes through the rotating sleeve axially and is connected to an external exhaust fan.

[0072] In this way, using an extraction pipe that is parallel to the air blowing pipe at intervals allows for better matching of the gas blown out by the air blowing pipe to achieve extraction and exhaust. In practice, the air outlet end of the extraction pipe extends outward through the connection part of the fixed support base at the discharge end and is connected to an external exhaust fan.

[0073] In this embodiment, the air extraction device further includes an air extraction guide housing 28 that is integrally arranged along the length of the air extraction pipe. The air extraction pipes 25 are arranged in parallel and are wrapped inside the air extraction guide housing 28. The air extraction guide housing 28 is located on the other side of the blowing guide housing inside the rotating sleeve, and its outer upper side is an arc shape that rotates with the inner end of the lifting plate. A purification chamber is formed between the upper part of the inner side of the air extraction guide housing and the inner side of the blowing guide housing. The lower end of the air extraction guide housing 28 is provided with an upward air extraction groove 29 corresponding to each air extraction pipe, and a porous filter material 27 is provided at the bottom of the air extraction groove 29 and connected to the air extraction hole of the corresponding air extraction pipe.

[0074] This is because the extraction pipe needs to have a thicker powder filter structure to prevent the powder from being carried away by the airflow, which results in lower extraction efficiency. Therefore, setting up multiple extraction pipes can better match the blowing rate of the blowing pipe and achieve better treatment results.

[0075] Example 2: In this Example 2, the air extraction device differs from that in Example 1, but the remaining features are the same as in Example 1. In this Example 2, the air extraction device includes an air extraction pipe 25 disposed within the rotating sleeve along its length and with its end relatively fixed to the outer casing. The air extraction pipe 25 is provided with an air extraction hole 26, and a powder filter structure is provided at the air extraction hole. The air outlet end of the air extraction pipe 25 extends axially through the rotating sleeve and is connected to an external exhaust fan.

[0076] In Example 2, the air extraction device further includes an air extraction guide housing 28. The air extraction guide housing is generally elongated along the length of the air extraction pipe and covers the air extraction pipe inside it. The air extraction guide housing is located on the other side of the blowing guide housing inside the rotating sleeve, and its outer upper side is an arc shape that rotates with the inner end of the lifting plate. A purification chamber is formed between the upper part of the inner side of the air extraction guide housing and the inner side of the blowing guide housing. The lower part of the inner side of the air extraction guide housing 28 has an extension baffle 30 extending outward and downward, and a powder filter structure and an air extraction hole are provided on the rear side of the extension baffle 30.

[0077] In this way, the air extraction guide housing better guides the movement of powder and airflow, allowing the powder to fall into the lower front part of the rotating sleeve's inner cavity under the combined action of the airflow from the second air outlet of the blowing device and the extended baffle of the extraction device, moving in the direction of the rotating sleeve's rotation. Meanwhile, the airflow, after passing downwards over the extended baffle, flows upwards from behind the baffle and through the powder filtering structure before entering the extraction pipe through the extraction port and being discharged externally, thus better assisting in the separation of airflow and powder.

[0078] The air extraction pipe 25 is located at the upper end of the air extraction guide housing 28. The powder filtration structure includes a porous filter material 27 located outside the air extraction hole, and a guide sedimentation chamber 31 located below the porous filter material 27 and arranged downward. The guide sedimentation chamber 31 has parallel baffles 32 arranged alternately on the left and right sides. The outer side of each baffle 32 is inclined downward so that several parallel and outwardly inclined baffle chambers 33 are formed between the baffles. The lower outer end of each baffle chamber is provided with a material leakage hole 34.

[0079] In this way, when the airflow enters the guide sedimentation chamber after passing the extended baffle at the lower end of the exhaust guide housing, it will be mixed with some powder. The powder and airflow are sequentially deflected by each baffle chamber and then rise to the porous filter material. During this process, due to the rotation of the rotating sleeve, the relatively sealed space formed between each lifting plate on the rotating sleeve and the outer side of the exhaust guide housing passes sequentially through the material leakage holes at the lower outer ends of each baffle chamber. Because the suction force in the baffle chamber is relatively strong, some of the gas in the relatively sealed space passing through the material leakage holes is drawn into the baffle chamber to reduce the air pressure suction force in the baffle chamber. This gradually makes the air pressure suction force from the material leakage holes in the upper baffle chamber lower than the air pressure suction force in the relatively sealed space it passes through. Thus, the powder in the baffle chambers closer to the upper position is more likely to settle and leak downwards from the material leakage holes. Therefore, this structure not only achieves directional discharge of waste gas, but also avoids the powder being directly drawn into the ceramic filter block, causing blockage and reducing suction efficiency.

[0080] The suspended end of the lifting plate of the rotating sleeve has a circumferential section that bends in the direction of the circle where the end is located. The direction of the bend is opposite to the rotation direction of the rotating sleeve.

[0081] In this way, the design of the deflection section can better improve the fit between the blowing guide shell and the suction guide shell, thus preventing airflow from entering. It also shortens the distance between adjacent lifting plates, ensuring that the inner end spacing between adjacent lifting plates is less than the distance between the material leakage holes of the uppermost and lowermost baffle chambers, making it more conducive to achieving material leakage in conjunction with the material leakage holes of the baffle chambers.

Claims

1. A method for removing impurities and purifying iron oxide powder material for lithium-ion batteries, characterized in that, In a temperature field, iron oxide powder material for lithium-ion batteries is thrown upwards and then dropped downwards. The dropped powder material is impacted by the sprayed protective gas flow. The protective gas flow carries away the gaseous impurities that have been released from the surface of the powder material, and the impurities are then drawn out and discharged to achieve purification.

2. The method for removing impurities and purifying iron oxide powder materials for lithium-ion batteries as described in claim 1, characterized in that, The protective gas is nitrogen or argon.

3. The method for removing impurities and purifying iron oxide powder materials for lithium-ion batteries as described in claim 1, characterized in that, The temperature of the temperature field is controlled within the range of 500℃-800℃.

4. The method for removing impurities and purifying iron oxide powder material for lithium-ion batteries as described in claim 1, characterized in that, This method relies on a continuous purification device for iron oxide powder materials used in lithium-ion batteries. The device includes a base, with a horizontally oriented cylindrical outer shell fixedly mounted on top. A heating device for inward heating is installed on the outer shell. A cylindrical rotating sleeve is rotatably and coaxially mounted inside the outer shell. Sealing structures are provided between the rotating sleeve's ends and the outer shell. Multiple inwardly protruding lifting plates are evenly distributed circumferentially inside the rotating sleeve, and the lifting plates are spirally oriented along the length of the rotating sleeve. An air-blowing purification device is also installed inside the rotating sleeve, comprising an air-blowing device and an air-extraction device. The air-blowing device includes an air-blowing pipe positioned within the rotating sleeve along its length, with its end fixed relative to the outer shell. The air-blowing pipe has an air outlet. The air inlet of the air-blowing pipe extends axially through the rotating sleeve and is connected to an external protective air source device. An external feed pipe is also connected to the feed end of the rotating sleeve, and a discharge channel is connected downwards to the discharge end of the rotating sleeve.

5. The method for removing impurities and purifying iron oxide powder material for lithium-ion batteries as described in claim 4, characterized in that, The heating device is an electric heating device; Both ends of the air blowing pipe are fixed to a vertically oriented disc-shaped fixed support. The outer middle of the fixed support has a cylindrical connecting part coaxially outward and fixedly connected to the base. The feeding end of the rotating sleeve has an end plate located outside the fixed support at that end. A cylindrical transmission part is coaxially fixed to the middle of the end plate. The transmission part is rotatably sleeved on the connecting part outside the fixed support at that end and is used to drive the rotating motor. There is a gap between the discharge end of the rotating sleeve and the inner side of the fixed support at that end for setting a discharge channel below. The feeding pipe passes through and is fixed to the fixed support at the feeding end, and its outer end protrudes outward from the connecting part outside the fixed support and is used to connect to the feeding device. The air inlet end of the air blowing pipe protrudes outward from the connecting part of the fixed support at the discharge end and is connected to a protective air source device.

6. The method for removing impurities and purifying iron oxide powder material for lithium-ion batteries as described in claim 5, characterized in that, The transmission part on the outer side of the end plate of the feed end of the rotating sleeve is rotatably and sealed to the fixed support base on the inner side and the outer shell end. The fixed support base on the discharge end is sealed and fixedly connected to the outer shell end of that end. A bearing support is provided between the outer side of the discharge end of the rotating sleeve and the corresponding inner side of the outer shell.

7. The method for removing impurities and purifying iron oxide powder material for lithium-ion batteries as described in claim 5, characterized in that, The inner end of the feed tube extends downward into the lower inner wall of the corresponding fixed support base for feeding. A feed hood is provided on the side wall of the fixed support base where the inner end of the feed tube is located, and the lower end of the feed hood is open. The inner wall of the rotating sleeve is also provided with partitions arranged in a ring along the circumference at intervals along the length direction, and the partitions are set at the same height as the lifting plate.

8. The method for removing impurities and purifying iron oxide powder material for lithium-ion batteries as described in claim 4, characterized in that, The air blowing device also includes an air blowing guide housing. The air blowing guide housing is generally elongated along the length of the air blowing pipe and covers the air blowing pipe inside it. The air blowing guide housing is located at the upper part of the side in front of the rotation direction of the inner cavity of the rotating sleeve. The upper outer side of the air blowing guide housing is an arc shape that rotates with the inner end of the lifting plate. A first air outlet is provided at the upper part of the inner side of the air blowing guide housing and is connected to the air blowing pipe. An elongated impeller along the length of the air blowing pipe is rotatably installed outside the first air outlet. The air outlet can drive the upper end of the impeller to rotate outward.

9. The method for removing impurities and purifying iron oxide powder material for lithium-ion batteries as described in claim 8, characterized in that, The upper end of the inner side of the air blowing guide housing has an upper material dropping surface that slopes downward and forward. An inward diversion groove is provided on the lower side of the upper material dropping surface. The first air outlet is located in the middle of the bottom surface of the diversion groove. An arc-shaped diversion baffle that matches the arc of the bottom surface of the groove is also provided at intervals outside the first air outlet in the diversion groove. The impeller is installed on the outside of the diversion baffle, and the upper end of the impeller extends upward beyond the upper end of the diversion baffle along its own arc. The lower end of the impeller is located above the lower end of the diversion baffle along its own arc. The lower side of the diversion groove extends outward and downward to form a lower material dropping surface. A second air outlet that blows downward is provided at the lower end of the lower material dropping surface and is connected to the air blowing pipe.

10. The method for removing impurities and purifying iron oxide powder material for lithium-ion batteries as described in claim 9, characterized in that, The first and second air outlets are evenly arranged along the length of the air blowing pipe.

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