A system and method for removing magnetic foreign matter from magnesium carbonate

Abstract

The application provides a system and method for removing magnetic impurities in magnesium carbonate, and belongs to the technical field of magnesium carbonate preparation process. The system for removing magnetic impurities in magnesium carbonate comprises first magnetic removal mechanism, purging and desorption mechanism, grinding mechanism and second magnetic removal mechanism which are sequentially connected. First, the first magnetic removal mechanism is used to remove large particle magnetic impurities in the magnesium carbonate raw material. Then, the purging system of the purging and desorption mechanism sprays gas to blow off the magnetic impurities adsorbed on the surface of the powder after magnetic removal. The magnetic filter screen at the upper end of the purging bin is used to realize secondary adsorption of the blown-off magnetic impurities. Subsequently, the powder is ground by the grinding mechanism and deeply removed by the second magnetic removal mechanism. Through the cooperation of the grading magnetic removal process and the mechanisms, the pre-positioned coarse magnetic removal, the purging and desorption fine impurity removal, and the post-grinding fine magnetic removal, the magnetic removal efficiency of the magnesium carbonate is effectively improved, the content of magnetic substances in the finished product is reduced, and the prepared magnesium carbonate meets the strict requirements of lithium battery materials on purity and content of magnetic impurities.

Description

Technical Field

[0001] This invention belongs to the field of magnesium carbonate preparation technology, and more specifically, relates to a system and method for removing magnetic foreign matter from magnesium carbonate. Background Technology

[0002] Adding magnesium carbonate to lithium batteries to improve conductivity can extend battery life, slow down self-discharge, improve storage performance, and increase the utilization rate of active materials. However, the performance of battery materials is greatly influenced by the purity and fineness of the magnesium carbonate, especially by the content of magnetic materials such as iron, chromium, and nickel.

[0003] Currently, the demagnetization method for magnesium carbonate mostly involves setting up a drawer-type demagnetizer downstream of the grinding mill. However, after the material is ground into finer particles, the magnetic material also becomes finer, and the small magnetic material is not easily attracted, resulting in low demagnetization efficiency. Magnesium carbonate cannot meet the requirements of battery materials. Summary of the Invention

[0004] The purpose of this invention is to provide a system and method for removing magnetic foreign matter from magnesium carbonate, aiming to improve the demagnetization efficiency of magnesium carbonate and meet the low magnetic requirements of battery materials.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: to provide a system and method for removing magnetic foreign matter from magnesium carbonate, comprising a first demagnetizing mechanism, a purging and desorption mechanism, a grinding mechanism and a second demagnetizing mechanism connected sequentially along the material conveying direction; The first demagnetizing mechanism is used to remove large magnetic impurities from the magnesium carbonate raw material; The purging and desorption mechanism is connected to the outlet end of the first demagnetizing mechanism. The purging and desorption mechanism includes a purging chamber, a magnetic filter screen disposed at the upper end of the purging chamber, and a purging system connected to the gas distribution end of the purging chamber. A powder flow channel is provided inside the purging chamber. The purging system sprays gas to blow off the magnetic impurities adsorbed on the surface of the first powder after demagnetization, and the magnetic filter screen adsorbs the blown-off magnetic impurities a second time.

[0006] In another embodiment of this application, the upper end of the purging chamber is provided with a feed pipe for connecting to the first demagnetizing mechanism, and the lower end of the purging chamber is provided with a discharge pipe for connecting to the grinding mechanism. The purging chamber is equipped with multiple baffles, which are set at an angle to the horizontal direction. The multiple baffles are arranged in a staggered manner along the longitudinal direction to form the powder flow channel.

[0007] As another embodiment of this application, the purging system includes: The bottom purging structure includes several bottom purging tubes, and the upper part of the bottom purging tubes is provided with purging holes; The central purging structure includes a purging chamber located below the baffle plate and air holes formed on the baffle plate; the air holes are perpendicular to the baffle plate. Both the bottom purge pipe and the purge chamber are connected to the air source of the purge system. A top exhaust pipe connects to the top of the purge chamber; a magnetic filter is provided at the inlet end of the top exhaust pipe.

[0008] In another embodiment of this application, the central purging structure further includes: An air intake pipe penetrates the side wall of the purge chamber, with one end of the air intake pipe extending into the purge chamber and then into the purge cavity.

[0009] In another embodiment of this application, the first demagnetizing mechanism is a double-layer demagnetizer.

[0010] As another embodiment of this application, the first demagnetizing mechanism includes: The demagnetizing box is provided with a first region and a second region; the upper end and the lower end of the first region are respectively provided with a feed inlet and a discharge outlet; A working housing is disposed inside the demagnetizing box. The working housing moves horizontally to switch between the first region and the second region. Both the upper and lower ends of the working housing are provided with material passage ports for material to pass through. A demagnetizing assembly is rotatably disposed within the demagnetizing chamber; the demagnetizing assembly includes a central rotating shaft and a demagnetizing roller assembly, one end of the central rotating shaft is connected to a drive motor; the demagnetizing roller assembly is arranged around the outer periphery of the central rotating shaft and is fixedly connected to the central rotating shaft; When the working housing is in the first region, the demagnetizing roller assembly is located inside the working housing; when the working housing is in the second region, the demagnetizing roller assembly is located outside the working housing.

[0011] In another embodiment of this application, a sliding track extending in a horizontal direction is provided on the side wall of the demagnetizing box, and a slider is provided on the side wall of the working housing, the slider being adapted to the sliding track; The working housing has a clearance opening on its side to allow the demagnetizing assembly to pass through.

[0012] In another embodiment of this application, the grinding mechanism is a disc pulverizer, and the grinding chamber of the grinding mechanism is provided with an inner liner, which is made of hard ceramic material.

[0013] In another embodiment of this application, the second demagnetizing mechanism has the same structure as the first demagnetizing mechanism, or the second demagnetizing mechanism is a drawer-type demagnetizer.

[0014] The beneficial effects of the system for removing magnetic foreign matter from magnesium carbonate provided by the present invention are as follows: Compared with the prior art, the system for removing magnetic foreign matter from magnesium carbonate of the present invention adds a first demagnetizing mechanism and a purging and desorption mechanism before the grinding process. The first demagnetizing mechanism removes large magnetic impurities first, avoiding the large magnetic impurities from being ground into finer magnetic impurities that are more difficult to remove during the grinding process; and performs special purging and desorption treatment on the magnetic impurities adsorbed on the powder surface after the first demagnetizing, and achieves secondary adsorption through a magnetic filter.

[0015] The first demagnetizing mechanism and the purging and desorption mechanism, together with the subsequent grinding mechanism and the second demagnetizing mechanism, form a complete demagnetizing process. This enables layered processing of magnesium carbonate raw materials, thereby improving the overall demagnetizing efficiency of magnesium carbonate and effectively reducing the content of magnetic substances in the finished magnesium carbonate product. Ultimately, the finished magnesium carbonate product meets the requirements of lithium battery materials for the purity and magnetic substance content of magnesium carbonate, solving the technical problems of low demagnetizing efficiency and the inability of magnesium carbonate products to meet the needs of battery materials in the existing technology.

[0016] Meanwhile, the sequential connection of each mechanism along the material conveying direction enables continuous operation of magnesium carbonate preparation, eliminating the need for intermediate shutdowns for impurity removal, thus improving the preparation efficiency of magnesium carbonate and meeting the needs of large-scale industrial production.

[0017] A method for removing magnetic foreign matter from magnesium carbonate is provided, comprising the following steps: Magnesium carbonate raw material is fed into the first demagnetizing unit to remove large magnetic impurities in the raw material and obtain the first powder. The first powder is fed into the purge chamber of the purge and desorption mechanism. The purge system purges the first powder to remove the magnetic impurities adsorbed on the surface of the first powder, thereby obtaining the second powder. The second powder is fed into the grinding mechanism for grinding to obtain a third powder that meets the particle size requirements; Finally, the third powder is conveyed to the second demagnetizing mechanism, which removes the small magnetic impurities remaining in the powder to obtain the finished magnesium carbonate product.

[0018] The beneficial effects of the method for removing magnetic foreign matter from magnesium carbonate provided by this invention are as follows: Compared with the prior art, the method for removing magnetic foreign matter from magnesium carbonate of this invention adopts the aforementioned system for removing magnetic foreign matter from magnesium carbonate and possesses all the beneficial effects of the aforementioned system. The method for removing magnetic foreign matter from magnesium carbonate provided in this application firstly demagnetizes the magnesium carbonate raw material through a first demagnetizing mechanism to remove large-particle magnetic impurities from the raw material. Then, it uses a purging and desorption mechanism to purge and desorb the first powder after demagnetization to remove magnetic impurities adsorbed on the powder surface. Subsequently, it uses a grinding mechanism to grind the powder to a required particle size. Finally, it uses a second demagnetizing mechanism to finely demagnetize the ground powder to remove residual small-particle magnetic impurities from the powder, ultimately obtaining a high-purity magnesium carbonate product. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of a system for removing magnetic foreign matter from magnesium carbonate, provided by the present invention. Figure 2 This is a schematic diagram of the purging and desorption mechanism provided in the first embodiment of the present invention; Figure 3 for Figure 2 Enlarged view of point A in the middle; Figure 4 This is a schematic diagram of the purging and desorption mechanism provided in the second embodiment of the present invention; Figure 5 This is a schematic diagram of the air intake tube provided in the first embodiment of the present invention; Figure 6 This is a schematic diagram of the air intake tube provided in the second embodiment of the present invention; Figure 7 This is a schematic diagram of the structure of the first demagnetizing mechanism of the present invention.

[0021] In the diagram: 100, First demagnetizing mechanism; 101, Demagnetizing housing; 102, Working shell; 103, Sliding rail; 104, Driving component; 105, Feed inlet; 106, Drive motor; 107, Central rotating shaft; 108, Rotating plate; 109, Demagnetizing roller; 110, Motor; 111, Cleaning plate; 112, Screw; 113, Discharge port; 114, Feed outlet; 200, Blowing mechanism. Desorption mechanism; 201, feed pipe; 202, discharge pipe; 203, purging chamber; 204, baffle plate; 205, bottom plate; 206, bottom purging pipe; 207, air intake pipe; 208, purging chamber; 209, magnetic filter; 210, extension pipe; 211, connecting pipe; 212, air hole; 213, branch pipe; 214, main pipe; 300, grinding mechanism; 400, second demagnetizing mechanism. Detailed Implementation

[0022] To make the technical problems to be solved, the technical solutions, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0023] Please see Figures 1 to 7 The present invention provides a system and method for removing magnetic foreign matter from magnesium carbonate. The system for removing magnetic foreign matter from magnesium carbonate includes a first demagnetizing mechanism 100, a purging and desorption mechanism 200, a grinding mechanism 300, and a second demagnetizing mechanism 400 connected sequentially along the material conveying direction. The first demagnetizing mechanism 100 is used to remove large-particle magnetic impurities from the magnesium carbonate raw material. The purging and desorption mechanism 200 is connected to the outlet end of the first demagnetizing mechanism 100. The purging and desorption mechanism 200 includes a purging chamber 203, a magnetic filter 209 disposed at the upper end of the purging chamber 203, and a purging system connected to the gas distribution end of the purging chamber 203. A powder flow channel is provided inside the purging chamber 203. The purging system sprays gas to blow off the magnetic impurities adsorbed on the surface of the first powder after demagnetization, and the magnetic filter 209 re-adsorbs the purged magnetic impurities.

[0024] In existing technologies, magnesium carbonate demagnetization is mostly achieved by setting up a drawer-type demagnetizer downstream of the grinding mill. After the material is ground into finer particles, the magnetic impurities also become finer, making it difficult to effectively adsorb these small magnetic impurities. This results in low demagnetization efficiency and fails to meet the stringent requirements for magnetic material content in magnesium carbonate used in batteries.

[0025] To improve demagnetization efficiency, this application proposes that magnesium carbonate raw materials first undergo preliminary removal of large-particle magnetic impurities via a first demagnetization mechanism 100, forming a first powder after demagnetization. The first powder is conveyed into the purge chamber 203 of the purge-desorption mechanism 200, moving along the powder flow channel within the chamber. At this time, the purge system sprays gas into the purge chamber 203. The gas fully contacts the first powder within the powder flow channel, blowing off magnetic impurities adsorbed and remaining on the powder surface due to the demagnetization process of the first demagnetization mechanism 100. The blown-up magnetic impurities move upwards with the airflow and are ultimately adsorbed and captured by the magnetic filter 209 located at the upper end of the purge chamber 203, achieving secondary adsorption of magnetic impurities. The powder that has completed purge-desorption (i.e., the second powder) continues to be conveyed to the grinding mechanism 300 for grinding. The ground powder (i.e., the third powder) then enters the second demagnetization mechanism 400 for subsequent demagnetization, finally obtaining a finished magnesium carbonate product with small particle size and low magnetic impurity content.

[0026] This invention provides a system for removing magnetic foreign matter from magnesium carbonate. Compared with the prior art, this application adds a first demagnetizing mechanism 100 and a purging and desorption mechanism 200 before the grinding process. The first demagnetizing mechanism 100 removes large magnetic impurities first, preventing large magnetic impurities from being ground into finer magnetic impurities that are more difficult to remove during the grinding process. The system also performs a special purging and desorption treatment on the magnetic impurities adsorbed on the powder surface after the first demagnetization, and achieves secondary adsorption through a magnetic filter 209.

[0027] The first demagnetizing mechanism 100 and the purging and desorption mechanism 200, together with the subsequent grinding mechanism 300 and the second demagnetizing mechanism 400, form a complete demagnetizing process. This process enables layered treatment of magnesium carbonate raw materials, thereby improving the overall demagnetizing efficiency of magnesium carbonate and effectively reducing the content of magnetic substances in the finished magnesium carbonate product. Ultimately, the finished magnesium carbonate product meets the requirements of lithium battery materials for magnesium carbonate purity and magnetic substance content, solving the technical problems of low demagnetizing efficiency and magnesium carbonate products being unable to meet the needs of battery materials in the existing technology.

[0028] Meanwhile, the sequential connection of each mechanism along the material conveying direction enables continuous operation of magnesium carbonate preparation, eliminating the need for intermediate shutdowns for impurity removal, thus improving the preparation efficiency of magnesium carbonate and meeting the needs of large-scale industrial production.

[0029] In some possible embodiments, please refer to Figures 2 to 4 The upper end of the purge chamber 203 is provided with a feed pipe 201 for connecting to the first demagnetizing mechanism 100, and the lower end of the purge chamber 203 is provided with a discharge pipe 202 for connecting to the grinding mechanism 300. Multiple baffles 204 are provided inside the purge chamber 203, and the baffles 204 are arranged at an angle to the horizontal direction, forming a powder flow channel by staggering the multiple baffles 204 along the longitudinal direction. The angle between the baffles 204 and the horizontal direction can be 30°-60°.

[0030] The first powder, after being processed by the first demagnetizing mechanism 100, enters the purge chamber 203 through the feed pipe 201 at the upper end of the purge chamber 203. Because the baffles 204 in the purge chamber 203 are at an angle to the horizontal direction and are arranged longitudinally in a staggered manner, a Z-shaped powder flow channel is formed. The first powder gradually moves downward along the Z-shaped powder flow channel formed by the baffles 204, and the final second powder is discharged from the discharge pipe 202 at the lower end of the purge chamber 203.

[0031] During this process, the gas ejected by the purging system comes into full contact with the powder in the bend of the powder flow channel, completing the purging and desorption operation.

[0032] The feed pipe 201 and the discharge pipe 202 are respectively located at the upper and lower ends of the purge chamber 203, so that the material can fall naturally by its own gravity without the need for additional conveying power components.

[0033] The powder flow channel formed by the baffles 204 at an angle to the horizontal direction and arranged longitudinally in a staggered manner effectively extends the residence time of the powder in the purge chamber 203 compared to a straight flow channel. This allows the powder to have more complete and comprehensive contact with the gas sprayed by the purge system, avoiding the problem of incomplete purge and desorption caused by insufficient residence time of the powder and insufficient contact with the gas.

[0034] Furthermore, the staggered baffles 204 can buffer the falling speed of the powder, preventing poor purging effect due to excessive falling speed. In addition, the bent powder flow channel can also guide the airflow of the blown magnetic impurities, allowing them to move more smoothly upward with the airflow to the magnetic filter 209 at the upper end of the purging chamber 203, where they are effectively adsorbed and captured, improving the efficiency of secondary adsorption.

[0035] Optionally, the magnetic filter 209 can be configured as a drawer.

[0036] In some possible embodiments, please refer to Figures 2 to 6The purging system includes a bottom purging structure, a middle purging structure, and a top exhaust pipe. The bottom purging structure includes several bottom purging pipes 206, with multiple purging holes evenly distributed on the upper part of each bottom purging pipe 206. The middle purging structure includes a purging chamber 208 located below the baffle plate 204 and air holes 212 formed on the baffle plate 204. The air holes 212 are perpendicular to the baffle plate 204. Both the bottom purging pipes 206 and the purging chamber 208 are connected to the air source of the purging system. The top exhaust pipe connects to the top of the purging chamber 203. A magnetic filter 209 is provided at the inlet end of the top exhaust pipe. A base plate 205 is provided at the lower end of the baffle plate 204, and the base plate 205, the baffle plate 204, and the inner wall of the purging chamber 203 enclose the purging chamber 208. Multiple air holes 212 are evenly distributed on the baffle plate 204, and the air holes 212 are perpendicular to the upper surface of the baffle plate 204.

[0037] An air source simultaneously supplies air to the bottom purge pipe 206 and the purge chamber 208. The bottom purge pipe 206 ejects air upwards through the upper purge hole to form a first airflow. This first airflow flows counter-currently along the powder flow channel, purging the powder falling from the bottom of the purge chamber 203 during its upward flow. When multiple bottom purge pipes 206 are provided, they can be arranged in parallel or radially. The air source can be dry compressed air or nitrogen.

[0038] like Figure 2 As shown, when the bottom purge pipes 206 are arranged in parallel, they are connected by a transverse connecting pipe 211, and the connecting pipe 211 is connected to the air source. The airflow from the air source is evenly distributed into the multiple bottom purge pipes 206 through the connecting pipe 211.

[0039] like Figure 4 As shown, when the bottom purge pipes 206 are radially distributed, multiple bottom purge pipes 206 are connected at the central axis of the purge chamber 203 to form a buffer chamber, and are connected to the air source by means of the extension pipe 210. The extension pipe 210 is L-shaped, with its transverse section penetrating the purge chamber 203 and connecting to the air pipe, and its longitudinal section connecting the transverse section and the buffer chamber where multiple bottom purge pipes 206 converge.

[0040] The gas in the purging chamber 208 is ejected upward through the air holes 212 on the baffle plate 204 perpendicular to the baffle plate 204 to form a second airflow, which purifies the powder remaining on the baffle plate 204 and improves the purging efficiency.

[0041] The central purging structure, by setting a purging chamber 208 below the baffle plate 204 and opening air holes 212 perpendicular to the baffle plate 204, allows gas to be sprayed vertically upward from below the baffle plate 204, directly acting on the powder remaining on the baffle plate 204. Since the air holes 212 are perpendicular to the baffle plate 204, the gas can vertically impact the powder surface, making it easier to blow off magnetic impurities adsorbed on the powder surface. This solves the problem that when the powder remains on the baffle plate 204, the side purging airflow is difficult to effectively act on the lower surface of the powder, resulting in incomplete purging.

[0042] The synergistic effect of the bottom and middle purging structures ensures that all parts of the powder are effectively contacted by the purging airflow, achieving all-round, no-dead-angle purging of magnetic impurities, greatly improving the purging and desorption effect, and allowing magnetic impurities on the powder surface to be blown off more thoroughly.

[0043] The top exhaust pipe provides a smooth discharge channel for the airflow containing magnetic impurities generated during purging, preventing the airflow from forming eddies in the purging chamber 203, which would prevent the magnetic impurities from being effectively transported to the magnetic filter 209. At the same time, placing the magnetic filter 209 at the inlet end of the top exhaust pipe allows it to adsorb and capture magnetic impurities before the airflow enters the exhaust pipe, preventing the magnetic impurities from being discharged from the purging chamber 203 with the airflow and causing secondary pollution, thus improving the efficiency and thoroughness of secondary adsorption.

[0044] In some possible embodiments, please refer to Figures 5 to 6 The central purging structure also includes an air intake pipe 207, which penetrates the side wall of the purging chamber 203. One end of the air intake pipe 207 extends into the purging chamber 203 and into the purging cavity 208. The air intake pipe 207 extends horizontally against the inner side wall of the purging chamber 203.

[0045] The gas supplied by the gas source is delivered to the purge chamber 208 through the gas inlet pipe 207. The gas inlet pipe 207 penetrates the side wall of the purge chamber 203 to allow the gas to enter the purge chamber 208 inside the purge chamber 203, thus providing gas to the purge chamber 208.

[0046] The horizontal extension of the air intake pipe 207 along the inner wall of the purge chamber 203 effectively prevents the air intake pipe 207 from protruding into the internal space of the purge chamber 203 and obstructing the falling of powder. This prevents powder from accumulating at the air intake pipe 207, ensuring smooth powder transport within the purge chamber 203 and avoiding problems such as reduced production efficiency and poor purging effect caused by material accumulation.

[0047] Optionally, the air intake pipe 207 may further include a main pipe 214 and multiple branch pipes 213. The main pipe 214 penetrates the side wall of the purge chamber 203 and extends into the purge cavity 208. The multiple branch pipes 213 are connected to the main pipe 214 by means of a connecting member, and air holes 212 are provided on the branch pipes 213. The gas in the main pipe 214 enters the purge cavity 208 through the air holes 212 on the branch pipes 213. The connecting member may be a tee fitting, a four-way fitting, etc.

[0048] In some possible embodiments, please refer to Figure 7 The first demagnetizing mechanism 100 is a double-layer demagnetizer.

[0049] After entering the double-layer demagnetizer, the magnesium carbonate raw material passes through the two demagnetizing structures of the double-layer demagnetizer in sequence. The two demagnetizing structures adsorb and remove large magnetic impurities of different particle sizes in the raw material. The first powder after preliminary demagnetization is conveyed to the subsequent purging and desorption mechanism 200.

[0050] Compared to single-layer demagnetizers, this method achieves dual-layer graded demagnetization of magnesium carbonate raw materials. The two-layer demagnetization structure allows for different demagnetization parameters to be set according to the particle size and magnetic strength of magnetic impurities. This enables large magnetic impurities of different sizes and magnetic properties to be adsorbed and removed in layers, avoiding the problem of some large magnetic impurities not being effectively adsorbed due to the limited demagnetization capacity of single-layer demagnetizers and entering subsequent processes with the raw materials.

[0051] Optionally, both layers of demagnetizers are rotary demagnetizers. The double-layer demagnetizer uses neodymium iron boron permanent magnets as the core magnetic source. The upper and lower magnetic rollers are independently set and rotate in opposite directions. The magnetic field strength of the upper demagnetizing structure is 8000 Gs, and the magnetic field strength of the lower demagnetizing structure is 10000 Gs.

[0052] In some possible embodiments, please refer to Figure 7 The first demagnetizing mechanism 100 includes a demagnetizing housing 101, a working housing 102, and a demagnetizing assembly. The demagnetizing housing 101 is divided into a first region and a second region. The upper and lower ends of the first region are respectively provided with an inlet 105 and an outlet 113. The working housing 102 is located within the demagnetizing housing 101 and can move horizontally to switch between the first and second regions. Both the upper and lower ends of the working housing 102 are provided with material passage ports 114. The demagnetizing assembly is rotatably located within the demagnetizing housing 101. The demagnetizing assembly includes a central rotating shaft 107 and a demagnetizing roller assembly. One end of the central rotating shaft 107 is connected to a drive motor 106. The demagnetizing roller assembly is arranged around the outer periphery of the central rotating shaft 107 and fixedly connected to it. When the working housing 102 is in the first region, the demagnetizing roller assembly is located inside the working housing 102. When the working housing 102 is in the second region, the demagnetizing roller assembly is located outside the working housing 102.

[0053] When the working housing 102 is in the first region, it is in the working state, that is, the demagnetizing state; when the working housing 102 is in the second region, it is in the iron cleaning state, at which time it is necessary to remove the magnetic impurities adsorbed on the demagnetizing roller group.

[0054] In operation: Magnesium carbonate raw material enters through the feed inlet 105 of the first area of ​​the demagnetizing box 101. At this time, the working shell 102 is in the first area, and the demagnetizing roller group is located inside the working shell 102. The raw material passes through the feed port 114 at the upper end of the working shell 102. During the process, the demagnetizing roller group rotates under the drive of the drive motor 106 and the central rotating shaft 107, adsorbing large magnetic impurities in the raw material. The first powder that has completed demagnetization passes through the feed port 114 at the lower end of the working shell 102 and then is discharged through the discharge port 113 at the lower end of the first area.

[0055] When the magnetic impurities adsorbed by the demagnetizing roller assembly reach a certain amount, the working housing 102 is moved horizontally to the second area. At this time, the demagnetizing roller assembly is located outside the working housing 102, allowing for the cleaning of the magnetic impurities adsorbed on the demagnetizing roller assembly. After cleaning, the working housing 102 is moved back to the first area to continue the demagnetization operation.

[0056] The demagnetizing housing 101 is provided with a first area and a second area. The working housing 102 is designed to be able to move horizontally to switch areas, which realizes the separation of demagnetizing operation and impurity cleaning operation. When it is necessary to clean the magnetic impurities on the demagnetizing roller group, it is only necessary to move the working housing 102 to the second area.

[0057] The demagnetizing assembly uses a rotary demagnetizer. The structure of the central rotating shaft 107 driving the demagnetizing roller assembly to rotate allows the demagnetizing roller assembly to make dynamic and full contact with the raw material. Compared with a fixed demagnetizing structure, the rotating demagnetizing roller assembly can more effectively adsorb large magnetic impurities in the raw material, improving demagnetizing efficiency. At the same time, the rotating structure can cause the raw material to turn over during the demagnetizing process, making it easier for magnetic impurities in the raw material to be adsorbed by the demagnetizing roller assembly, avoiding the problem of incomplete local demagnetization caused by raw material accumulation.

[0058] In some possible embodiments, please refer to Figure 7 The demagnetizing housing 101 has a horizontally extending sliding track 103 on its side wall, and a slider is provided on the side wall of the working housing 102, which is adapted to the sliding track 103. A clearance opening is provided on the side of the working housing 102 to allow the demagnetizing assembly to pass through. A driving component 104 is provided on the demagnetizing housing 101, and the driving end of the driving component 104 is connected to the working housing 102 to drive the working housing 102 to move horizontally along the sliding track 103. The driving component 104 can be a cylinder or the like.

[0059] The working housing 102 moves smoothly in the horizontal direction by cooperating with the sliding track 103 on the side wall of the demagnetizing box 101 via a slider on the side wall, completing the switching between the first and second regions. The clearance opening on the side of the working housing 102 provides passage space for the demagnetizing roller group of the demagnetizing assembly, ensuring that the demagnetizing roller group can pass smoothly through the clearance opening during the movement of the working housing 102, realizing the switching of the position of the demagnetizing roller group inside and outside the working housing 102.

[0060] Optionally, the demagnetizing assembly also includes two rotating plates 108 spaced apart on the central rotating shaft 107. The rotating plates 108 are coaxial with and fixedly connected to the central rotating shaft 107, and rotate synchronously with the central rotating shaft 107. The demagnetizing roller assembly includes multiple demagnetizing roller bodies 109, which are distributed along the length of the central rotating shaft 107, and their two ends are respectively connected to the two rotating plates 108. The demagnetizing roller bodies 109 rotate synchronously with the rotating plates 108. The drive motor 106 is located on the outside of the demagnetizing housing 101. The central rotating shaft 107 is fixed to the demagnetizing housing 101 by means of bearings and extends into the interior of the demagnetizing housing 101 through the side plate. In addition, the rotating plates 108 are adapted to the clearance opening, and the outer ring of the rotating plates 108 is also provided with an annular sealing ring, which is used to cover the gap between the rotating plates 108 and the clearance opening.

[0061] The demagnetizing assembly also includes a cleaning plate 111 sleeved on the central rotating shaft 107. The cleaning plate 111 is clearance-fitted with the central rotating shaft 107 and is coaxially arranged with the central rotating shaft 107. The cleaning plate 111 has cleaning holes corresponding to a plurality of demagnetizing rollers 109. The cleaning holes are sleeved and connected to the demagnetizing rollers 109 and rotate around the central rotating shaft 107 with the demagnetizing rollers 109. The inner sidewall of each cleaning hole is provided with a brush structure or a silicone ring. In the iron-cleaning state, the cleaning plate 111 moves along the length direction of the demagnetizing roller 109, and uses the brush structure or silicone ring to remove the magnetic impurities adsorbed on the outer surface of the demagnetizing roller 109.

[0062] A fixing plate is also provided on the central rotating shaft 107. The fixing plate is located on the side of the rotating plate 108 near the motor. The fixing plate is fixedly connected to the central rotating shaft 107 and rotates synchronously with the central rotating shaft 107.

[0063] Several fixing brackets are provided on the fixing plate, and motors 110 are mounted on the fixing brackets. Screws 112 are also provided on the fixing plate, arranged axially along the central rotating shaft 107. The screws 112 pass sequentially through the first rotating plate 108, the cleaning plate 111, and extend to another rotating plate 108. The cleaning plate 111 is threadedly connected to the screws 112. When the central rotating shaft 107 rotates, the motor 110 stops, and the cleaning plate 111 returns to its position against any of the rotating plates 108. When cleaning the demagnetizing roller 109, the working housing 102 moves to the second area. At this time, the central rotating shaft 107 stops working, the motor 110 starts working, and the motor 110 drives the screws 112 to rotate, causing the cleaning plate 111 to move axially along the central rotating shaft 107. During the movement of the cleaning plate 111, the brush structure or silicone ring on the cleaning plate 111 removes magnetic impurities from the surface of the demagnetizing roller 109.

[0064] Optionally, the demagnetizing roller body 109 includes a central magnetized section and two non-magnetic sections at both ends. Two corrugated sleeves can be provided on the outer side of the screw 112, and the corrugated sleeves are retractable. The two corrugated sleeves are located on both sides of the cleaning plate 111, and when the cleaning plate 111 is not working, it is in the non-magnetic section of the demagnetizing roller body 109. When the cleaning plate 111 moves, the two corrugated sleeves extend and retract accordingly to ensure that the surface of the screw 112 is always within the corrugated sleeves.

[0065] The corrugated sleeve is fixedly connected to the cleaning plate 111. The cleaning plate 111 is equipped with a threaded sleeve that matches the screw 112, and the threaded sleeve is fixedly connected to the cleaning plate 111.

[0066] One or more screws 112 may be used, such as four screws 112 evenly distributed circumferentially along the central axis 107. Multiple demagnetizing rollers 109 may be provided, such as six demagnetizing rollers 109 evenly distributed circumferentially along the central axis 107.

[0067] In some possible embodiments, the grinding mechanism 300 is a disc mill, and the grinding chamber of the grinding mechanism 300 is lined with a hard ceramic material. The magnesium carbonate powder, after being processed by the purging and desorption mechanism 200, enters the grinding chamber of the disc mill. The disc mill grinds the powder through the relative movement of the grinding discs, achieving the required particle size. The hard ceramic liner inside the grinding chamber is in direct contact with the powder, providing support and protection for the grinding operation. The hard ceramic material can be alumina ceramic or silicon nitride ceramic.

[0068] A hard ceramic liner is installed inside the grinding chamber so that the powder only comes into contact with the hard ceramic liner during the grinding process. Compared with the traditional metal liner, the hard ceramic material is non-ferromagnetic and will not produce magnetic impurities such as iron due to wear during the grinding process, thus avoiding the introduction of new magnetic impurities into the magnesium carbonate powder by the grinding mechanism 300.

[0069] In addition, the surface of hard ceramic material is smooth and does not easily adsorb magnesium carbonate powder, which can prevent the powder from accumulating in the grinding chamber, ensuring smooth grinding operation and improving grinding efficiency.

[0070] The second demagnetizing mechanism 400 has the same structure as the first demagnetizing mechanism 100, or the second demagnetizing mechanism 400 can be a drawer-type demagnetizer.

[0071] The magnesium carbonate powder, after being ground by the grinding mechanism 300, enters the second demagnetizing mechanism 400 for further demagnetization.

[0072] If the second demagnetizing mechanism 400 has the same structure as the first demagnetizing mechanism 100, then the residual small magnetic impurities in the powder are removed according to the demagnetizing principle of the first demagnetizing mechanism 100.

[0073] If the second demagnetizing mechanism 400 is a drawer-type demagnetizer, the magnetic adsorption structure of the drawer-type demagnetizer will adsorb and remove residual small magnetic impurities in the powder, and finally obtain high-purity magnesium carbonate product.

[0074] A method for removing magnetic foreign matter from magnesium carbonate is also provided, comprising the following steps: Magnesium carbonate raw material is fed into the first demagnetizing unit 100 to remove large magnetic impurities in the raw material and obtain the first powder. The first powder is fed into the purge chamber 203 of the purge and desorption mechanism 200. The purge system purges the first powder to remove the magnetic impurities adsorbed on the surface of the first powder, thereby obtaining the second powder. The second powder is fed into the grinding mechanism 300 for grinding to obtain a third powder that meets the particle size requirements; Finally, the third powder is conveyed to the second demagnetizing unit 400, which removes residual small magnetic impurities from the powder to obtain the finished magnesium carbonate product.

[0075] This invention provides a method for removing magnetic foreign matter from magnesium carbonate. Compared with the prior art, it employs the aforementioned system for removing magnetic foreign matter from magnesium carbonate and possesses all its beneficial effects. The method for removing magnetic foreign matter from magnesium carbonate provided in this application firstly demagnetizes the magnesium carbonate raw material using a first demagnetizing mechanism 100 to remove large-particle magnetic impurities. Then, a purging and desorption mechanism 200 purges and desorbs the demagnetized first powder to remove magnetic impurities adsorbed on the powder surface. Subsequently, a grinding mechanism 300 grinds the powder to a required particle size. Finally, a second demagnetizing mechanism 400 performs fine demagnetization on the ground powder to remove residual small-particle magnetic impurities, ultimately obtaining a high-purity magnesium carbonate product.

[0076] This preparation method places the demagnetization process before the grinding process, removing large magnetic impurities first. This avoids the large magnetic impurities from being ground into finer magnetic impurities that are more difficult to remove during the grinding process, thus reducing the pressure on subsequent demagnetization processes from the source and solving the technical problem of low demagnetization efficiency caused by the grinding of magnetic impurities in the prior art.

[0077] A purging and desorption process is added after the first demagnetization step to specifically remove magnetic impurities adsorbed on the powder surface, achieving stratified removal of magnetic impurities of different particle sizes and existence forms. The grinding process is placed between the two demagnetization steps, allowing the ground powder to promptly enter the second demagnetization unit 400 for fine demagnetization, removing any magnetic impurities that may remain from the grinding process. This results in magnesium carbonate with high purity and low magnetic content, meeting the stringent requirements for magnesium carbonate in lithium battery materials.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for removing magnetic foreign matter from magnesium carbonate, characterized in that, It includes a first demagnetizing mechanism (100), a purging and desorption mechanism (200), a grinding mechanism (300), and a second demagnetizing mechanism (400) connected sequentially along the material conveying direction; The first demagnetizing mechanism (100) is used to remove large magnetic impurities from the magnesium carbonate raw material; The purging and desorption mechanism (200) is connected to the outlet end of the first demagnetizing mechanism (100). The purging and desorption mechanism (200) includes a purging chamber (203), a magnetic filter (209) disposed at the upper end of the purging chamber (203), and a purging system connected to the gas distribution end of the purging chamber (203). A powder flow channel is provided inside the purging chamber (203). The purging system sprays gas to blow off the magnetic impurities adsorbed on the surface of the first powder after demagnetization, and the magnetic filter (209) adsorbs the blown-off magnetic impurities a second time.

2. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 1, characterized in that, The upper end of the purge chamber (203) is provided with a feed pipe (201) for connecting to the first demagnetizing mechanism (100), and the lower end of the purge chamber (203) is provided with a discharge pipe (202) for connecting to the grinding mechanism (300). The purge chamber (203) is provided with a plurality of baffles (204), which are arranged at an angle to the horizontal direction. The plurality of baffles (204) are arranged in a staggered manner along the longitudinal direction to form the powder flow channel.

3. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 2, characterized in that, The purging system includes: The bottom purging structure includes a plurality of bottom purging pipes (206), and the upper part of the bottom purging pipes (206) is provided with purging holes; The central purging structure includes a purging chamber (208) located below the baffle plate (204) and an air hole (212) opened on the baffle plate (204); the air hole (212) is perpendicular to the baffle plate (204); Both the bottom purge pipe (206) and the purge chamber (208) are connected to the air source of the purge system; A top exhaust pipe is connected to the top of the purge chamber (203); a magnetic filter (209) is provided at the inlet end of the top exhaust pipe.

4. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 3, characterized in that, The central purging structure also includes: An air intake pipe (207) penetrates the side wall of the purge chamber (203), and one end of the air intake pipe (207) extends into the purge chamber (203) and into the purge cavity (208).

5. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 1, characterized in that, The first demagnetizing mechanism (100) is a double-layer demagnetizer.

6. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 1, characterized in that, The first demagnetizing mechanism (100) includes: A demagnetizing box (101) is provided with a first region and a second region; the upper end and the lower end of the first region are respectively provided with a feed inlet (105) and a discharge outlet (113); The working housing (102) is disposed inside the demagnetizing box (101). The working housing (102) moves horizontally to switch between the first region and the second region. The upper and lower ends of the working housing (102) are provided with material passage ports (114) for material to pass through. A demagnetizing assembly is rotatably disposed within the demagnetizing housing (101); the demagnetizing assembly includes a central rotating shaft (107) and a demagnetizing roller assembly, one end of the central rotating shaft (107) is connected to a drive motor (106); the demagnetizing roller assembly is arranged around the outer periphery of the central rotating shaft (107) and is fixedly connected to the central rotating shaft (107); When the working housing (102) is in the first region, the demagnetizing roller assembly is located inside the working housing (102); when the working housing (102) is in the second region, the demagnetizing roller assembly is located outside the working housing (102).

7. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 6, characterized in that, The demagnetizing box (101) is provided with a sliding track (103) extending in the horizontal direction on its side wall, and the working housing (102) is provided with a slider on its side wall, the slider being adapted to the sliding track (103); The working housing (102) has a clearance opening on its side to allow the demagnetizing assembly to pass through.

8. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 1, characterized in that, The grinding mechanism (300) is a disc pulverizer, and the grinding chamber of the grinding mechanism (300) is provided with an inner liner, which is made of hard ceramic material.

9. The system for removing magnetic foreign matter from magnesium carbonate as described in claim 1, characterized in that, The second demagnetizing mechanism (400) has the same structure as the first demagnetizing mechanism (100), or the second demagnetizing mechanism (400) is a drawer-type demagnetizer.

10. A method for removing magnetic foreign matter from magnesium carbonate, characterized in that, Includes the following steps: Magnesium carbonate raw material is fed into the first demagnetizing unit (100) to remove large magnetic impurities in the raw material and obtain the first powder; The first powder is fed into the purge chamber (203) of the purge and desorption mechanism (200). The purge system purges the first powder to remove the magnetic impurities adsorbed on the surface of the first powder, thereby obtaining the second powder. The second powder is fed into the grinding mechanism (300) for grinding to obtain a third powder that meets the particle size requirements; Finally, the third powder is conveyed to the second demagnetizing mechanism (400), which removes the small magnetic impurities remaining in the powder to obtain the finished magnesium carbonate product.

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