High-temperature calcination process and apparatus for lithium mica based on exhaust gas purification

Abstract

This invention relates to the field of lepidolite calcination technology, and particularly to a high-temperature calcination process and apparatus for lepidolite based on tail gas purification. The apparatus includes a calcination kiln body, and a feed hopper and a discharge cylinder rotatably connected to both ends of the kiln body. The kiln body is equipped with a conveying and screening mechanism for graded calcination of lepidolite, and a recovery and purification mechanism for multi-stage treatment of calcination tail gas is located on one side of the kiln body. This invention achieves graded conveying and processing of lepidolite through the counter-rotation of the kiln body and the rotating cylinder, controlling the transit time of lepidolite within the kiln body. This avoids the phenomenon of some lepidolite being discharged too slowly or too quickly, leading to local over-calcination or incomplete calcination. The graded screening calcination process for lepidolite allows small lepidolite particles to be retained by the screening mesh, delaying discharge and extending the calcination interval, creating a difference in calcination time between small and large lepidolite particles. This effectively avoids the problems of over-calcination of small particles and incomplete calcination of large particles.

Description

Technical Field

[0001] This invention relates to the field of lithium mica calcination technology, and in particular to a high-temperature calcination process and apparatus for lithium mica based on exhaust gas purification treatment. Background Technology

[0002] With the rapid development of the new energy industry, the demand for lithium resources continues to rise. As an important raw material for lithium extraction, the efficiency and environmental friendliness of its high-temperature calcination process have become the core focus of the industry. Currently, calcination of lepidolite mostly adopts traditional rotary kilns or tunnel kilns.

[0003] In the material handling stage, due to the large differences in particle size in lepidolite ore, existing technologies lack targeted graded conveying and calcination rhythm control mechanisms: a single linear conveying or overall tilting conveying method is often used, and lepidolite of all sizes follows the same residence time and heating path in the kiln. Small particles, due to their large surface area and fast thermal response, are prone to over-burning within the standard calcination cycle, resulting in excessive volatilization of lithium or coking of the material, affecting the purity of subsequent lithium extraction; large particles, due to their low internal heat transfer efficiency, often have the problem of under-burning, where the surface is fully calcined but the core is unreacted, requiring secondary re-calcination, ultimately causing the overall calcination quality to be unstable.

[0004] To address the aforementioned technical deficiencies, a solution is proposed that utilizes a rotating cylinder that rotates in the opposite direction to the calcining kiln body. This allows for graded transport and differentiated calcination of lepidolite based on particle size, precisely controlling the overall calcination time of the lepidolite while simultaneously screening and retaining smaller particles to extend the calcination interval. This differentiates the calcination time between the smaller and larger particles, effectively avoiding the problems of over-calcination of small particles and incomplete calcination of large particles. Summary of the Invention

[0005] The purpose of this invention is to provide a high-temperature calcination process and apparatus for lithium mica based on exhaust gas purification, in order to solve the aforementioned technical defects.

[0006] The objective of this invention can be achieved through the following technical solution: a high-temperature calcination device for lithium mica based on tail gas purification treatment, comprising a calcination kiln body, a burner rotatably mounted on the annular outer wall of the calcination kiln body, and a feed hopper and a discharge cylinder rotatably connected to both ends of the calcination kiln body, wherein a conveying and screening mechanism for graded calcination of lithium mica is provided inside the calcination kiln body, and a recovery and purification mechanism for multi-stage treatment of calcination tail gas is provided on one side of the calcination kiln body.

[0007] Preferably, the material conveying and screening mechanism includes a rotating cylinder located inside the calcining kiln and coaxially arranged therewith. Two sets of shovel blocks that are slidably connected to the inner wall of the calcining kiln are fixedly connected to the outer wall of the rotating cylinder. Several feed troughs that penetrate into the rotating cylinder are equidistantly opened on the shovel blocks along their length direction, and a screening screen is fixedly connected inside the feed troughs.

[0008] Preferably, the inner wall of the rotating cylinder is provided with an arc-shaped groove, and an arc-shaped plate that is slidably connected to the arc-shaped groove is fixedly connected to it by several springs. One side of the arc-shaped plate abuts against the screening screen. An elastic rod is fixedly connected to the concave side of the arc-shaped plate. The inner wall of the rotating cylinder is provided with a slot for the elastic rod to pass through and slide.

[0009] Preferably, a plurality of Z-shaped baffles are fixedly connected to the inner wall of the rotating cylinder, the feed trough is located between two adjacent sets of Z-shaped baffles, and a discharge port penetrating the side wall of the rotating cylinder is opened between the free ends of the two adjacent sets of Z-shaped baffles. A limiting plate is fixedly connected between the two sets of shovel blocks and on the side of the corresponding feed trough away from the feed hopper.

[0010] Preferably, the rotating cylinder is provided with an L-shaped guide block inside, and the L-shaped guide block has a plurality of L-shaped guide grooves equidistantly opened along its length direction inside, and both sides of the L-shaped guide block are equipped with stop bars that cooperate with the elastic rod.

[0011] Preferably, a rotating sleeve that is rotatably connected to the feed hopper is fixedly connected to the rotating cylinder, and a support rod one and a support rod two are fixedly connected to both sides of the L-shaped guide block, respectively. The support rod one is rotatably connected to the rotating sleeve, and the support rod two is fixedly connected to the discharge cylinder.

[0012] Preferably, the recycling and purification mechanism includes a purification cylinder, the interior of which is divided into an upper purification chamber and a lower recycling chamber by a fixedly connected partition. A modified molecular sieve layer is installed in the lower recycling chamber, an alkaline activated carbon layer is installed at the top of the upper purification chamber, and a calcium chloride solution is injected into the bottom of the upper purification chamber.

[0013] Preferably, an air suction pipe is fixedly connected between the lower recovery chamber and the discharge cylinder, and a negative pressure fan is installed on the air suction pipe. A T-shaped pipe communicating with the lower recovery chamber is fixedly connected to the top of the partition, and several dispersion holes are opened on the outer wall of the end of the T-shaped pipe. An exhaust pipe is installed on the top of the purification cylinder.

[0014] Preferably, the purification cylinder is fixedly connected to the top and bottom sides of the modified molecular sieve layer by a second gas pipe and a first gas pipe, respectively. A one-way valve is installed on the first gas pipe, and control valves are installed on both the second gas pipe and the T-shaped pipe. A condenser is installed on the second gas pipe.

[0015] The high-temperature calcination process of lithium mica based on exhaust gas purification includes the following steps:

[0016] S1: The calcination process of lepidolite is carried out by screening and grading: the calcination kiln and the rotating drum rotate slowly at the same time and in opposite directions. When the material is rotated to the lowest point, the feed chute of the shovel block shovels the lepidolite in the calcination kiln into the rotating drum. The screening screen screens and retains small lepidolite particles for temporary storage. When the material is raised to the highest point, it is discharged into the calcination kiln again. Large lepidolite particles that do not pass the screening are discharged into the calcination kiln again and quickly for differentiated and intermittent calcination treatment. This avoids the over-calcination of small lepidolite particles while preventing large lepidolite particles from being incompletely calcined.

[0017] S2: Multi-stage purification treatment of calcination tail gas: The tail gas first passes through a modified molecular sieve layer to physically adsorb lithium vapor, then passes through a calcium chloride solution to remove fluoride, and then passes through alkaline activated carbon to adsorb acidic gases, thus completing the purification treatment of the tail gas.

[0018] S3: Lithium recovery process: High-temperature inert nitrogen gas is introduced into the modified molecular sieve layer to weaken the physical adsorption force, so that lithium elements are desorbed from the surface of the molecular sieve in the form of lithium dioxide vapor or lithium ions. Then, the lithium is condensed in the condenser with the nitrogen gas flow to form a lithium solution for recovery.

[0019] The beneficial effects of this invention are as follows:

[0020] (1) This invention achieves graded conveying and processing of lepidolite by coordinating the counter-rotation of the calcining kiln body and the rotating cylinder, relying on the shovel block, screening screen, Z-shaped baffle, L-shaped guide block and other structures, thereby controlling the transit time of lepidolite in the calcining kiln body and avoiding the phenomenon of some lepidolite being discharged too slowly or too quickly, resulting in local over-calcination or incomplete calcination. At the same time, it also performs graded screening calcination treatment on lepidolite, so that small particles of lepidolite are intercepted by the screening screen and the discharge is delayed, thus extending the calcination interval time, while large particles of lepidolite are quickly guided out, forming a difference in calcination time, effectively avoiding the problem of over-calcination of small particles and incomplete calcination of large particles.

[0021] (2) This invention achieves multi-stage treatment of calcination tail gas, including lithium recovery, fluoride removal, and acid gas adsorption: the tail gas first undergoes selective adsorption of lithium vapor by van der Waals forces in a modified molecular sieve layer, laying the foundation for subsequent lithium resource recovery, and then enters a calcium chloride solution to remove fluoride. An alkaline activated carbon layer adsorbs acid gas, achieving stepwise removal of pollutants in the tail gas. The lithium vapor adsorbed by the molecular sieve is desorbed by high-temperature inert nitrogen and then condensed to form a lithium solution for recovery, achieving the effect of purifying the tail gas while realizing the secondary recycling of lithium resources. Attached Figure Description

[0022] The invention will now be further described with reference to the accompanying drawings;

[0023] Figure 1 This is a flowchart of the process of the present invention;

[0024] Figure 2 This is a schematic diagram of the structure of the present invention;

[0025] Figure 3 This is an installation diagram of the material conveying and screening mechanism of the present invention;

[0026] Figure 4 This is a schematic diagram of the installation of the material shovel block of the present invention;

[0027] Figure 5 This is a schematic diagram showing the disassembled rotating cylinder and arc-shaped plate of the present invention;

[0028] Figure 6 This is a schematic diagram of the cooperation between the rotating cylinder and the arc-shaped plate of the present invention;

[0029] Figure 7 This is a schematic diagram of the installation of the rotating cylinder and the L-shaped guide block of the present invention;

[0030] Figure 8 This is a schematic diagram of the cooperation between the arc-shaped plate and the L-shaped guide block of the present invention;

[0031] Figure 9 This is a schematic diagram of the structure of the L-shaped guide block of the present invention;

[0032] Figure 10 This is a schematic diagram of the recycling and purification mechanism of the present invention.

[0033] Legend:

[0034] 1. Calcination kiln body; 11. Feed hopper; 12. Discharge cylinder;

[0035] 2. Material conveying and screening mechanism; 21. Rotating cylinder; 22. Material shovel block; 23. Feed chute; 24. Screening mesh; 25. Spring; 26. Arc plate; 27. Elastic rod; 28. Z-shaped baffle; 29. ​​Discharge port; 210. Material limiting plate; 211. L-shaped guide block; 212. Guide chute; 213. Stop bar;

[0036] 3. Recycling and purification mechanism; 31. Purification cylinder; 32. Upper purification chamber; 33. Lower recycling chamber; 34. Suction pipe; 35. T-shaped pipe; 36. Second air pipe; 37. First air pipe; 38. Condenser. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1: Please refer to Figures 2-9 As shown, the problem that lepidolite of all particle sizes follows the same residence time and heating path in the kiln in the existing technology, which leads to over-calcination of small particles or incomplete calcination of large particles, can be solved by the following solution;

[0039] In this embodiment, a high-temperature calcination device for lepidolite based on exhaust gas purification includes a calcination kiln body 1. A burner is rotatably mounted on the annular outer wall of the calcination kiln body 1 to heat the calcination kiln body 1. A feed hopper 11 and a discharge cylinder 12 are rotatably connected at both ends of the calcination kiln body 1 for injecting lepidolite and discharging it after calcination. An inclined surface is provided on the inner wall of the calcination kiln body 1 on one side of the feed hopper 11 to assist the lepidolite in quickly contacting the shovel block 22 after injection, thereby realizing the smooth conveying and processing of lepidolite in the calcination kiln body 1. The interior of the calcination kiln body 1 is provided with a conveying and screening mechanism 2 for graded calcination of lepidolite. A recovery and purification mechanism 3 for multi-stage treatment of calcination exhaust gas is provided on one side of the calcination kiln body 1.

[0040] The material conveying and screening mechanism 2 includes a rotating cylinder 21 located inside the calcining kiln body 1 and coaxially arranged therewith. The calcining kiln body 1 and the rotating cylinder 21 rotate slowly at the same time but in opposite directions. Two sets of shovel blocks 22 are fixedly connected to the outer wall of the rotating cylinder 21 and are slidably connected to the inner wall of the calcining kiln body 1. Several feed troughs 23 that penetrate into the interior of the rotating cylinder 21 are equidistantly opened on the shovel blocks 22 along their length direction. A screening screen 24 is fixedly connected inside the feed troughs 23.

[0041] The rotating drum 21 carries two sets of shovel blocks 22 and rotates circumferentially. The shovel blocks 22 rotate to the lowest point and feed the lithium mica in the calcining kiln 1 through the feed trough 23. The lithium mica is shoveled into the rotating drum 21 and calcined by intermittent calcination. The smaller lithium mica particles are screened into the feed trough 23 below the screen 24 through the screening screen 24, thus completing the screening process of large and small lithium mica particles.

[0042] With a fixed overall calcination time, the discharge time of large and small lepidolite particles is controlled to limit the calcination time of large and small lepidolite particles respectively, thereby creating a difference in calcination time and effectively avoiding the problems of over-calcination of small particles and incomplete calcination of large particles.

[0043] An arc-shaped groove is provided on the inner wall of the rotating cylinder 21, and an arc-shaped plate 26 is slidably connected to the groove by several springs 25. One side of the arc-shaped plate 26 abuts against the screening screen 24. Through the abutment between the side of the arc-shaped plate 26 and the screening screen 24, when the shovel block 22 shovels the lepidolite in the calcining kiln 1, the large particles of lepidolite and the small particles of lepidolite will not come into contact too quickly as the rotating cylinder 21 rotates, thereby controlling the time when the large and small particles of lepidolite are discharged from the inside of the rotating cylinder 21. An elastic rod 27 is fixedly connected to the concave side of the arc-shaped plate 26, and a groove is provided on the inner wall of the rotating cylinder 21 for the elastic rod 27 to pass through and slide.

[0044] Multiple Z-shaped baffles 28 are fixedly connected to the inner wall of the rotating cylinder 21. The feed chute 23 is located between two adjacent sets of Z-shaped baffles 28, and a discharge port 29 that penetrates the side wall of the rotating cylinder 21 is opened between the free ends of the two adjacent sets of Z-shaped baffles 28.

[0045] The rotating drum 21 is located on one side of the feed hopper 11. The second feed chute 23 and the first discharge port 29 are on the same annular surface, and multiple feed chute 23 are located on the discharge port 29 on one side of the discharge drum 12. This allows large particles of lepidolite that have not passed the screening to be discharged from the rotating drum 21 and automatically enter the rotating drum 21 of the next calcination zone. Then, they are quickly guided to the discharge port 29 on one side by the arc plate 26 and the Z-shaped baffles 28 on both sides of the corresponding feed chute 23. They are then quickly discharged into the calcination kiln 1 for calcination treatment at short intervals. The shovel block 22 screens the lepidolite, which can further increase the uniform calcination treatment of the lepidolite.

[0046] Two sets of shovel blocks 22 are fixedly connected to a limiting plate 210 on the side of the corresponding feed chute 23 away from the feed hopper 11. This plate is used to limit the rapid movement of a portion of the lepidolite within the calcining kiln 1 and to allow for reverse flow, thereby dividing the calcining zone into multiple zones. Combined with the shovel blocks 22, the screening screen 24, the arc plate 26, and the Z-shaped baffle 28, the lepidolite is conveyed in stages, controlling the transit time of the lepidolite within the calcining kiln 1 and preventing some lepidolite from being discharged too slowly or too quickly, which could lead to local over-calcination or incomplete calcination.

[0047] The rotating cylinder 21 is equipped with an L-shaped guide block 211. The L-shaped guide block 211 has several L-shaped guide grooves 212 evenly spaced along its length. The top of each guide groove 212 is connected to the corresponding feed groove 23, and its bottom is connected to the corresponding discharge port 29. Both sides of the L-shaped guide block 211 are equipped with a stop bar 213 that cooperates with the elastic rod 27.

[0048] After the shovel block 22 rotates from the lowest point to the highest point, the elastic rod 27 on the arc plate 26 abuts against the stop rod 213 on the L-shaped guide block 211, briefly restricting the synchronous rotation of the arc plate 26, causing the arc plate 26 to compress the spring 25 and retract into the arc groove, and the small particles of lithium mica between the screening screen 24 and the feed chute 23 are discharged into the corresponding guide chute 212 on the L-shaped guide block 211;

[0049] Then it is guided to the discharge port 29 on the side of another set of shovel blocks 22 and discharged into the calcining kiln 1 again to calcine the small particles of lithium mica at long intervals. As the rotating cylinder 21 rotates, the elastic rod 27 deforms and separates from the stop rod 213. The arc plate 26 resets under the compression force of the spring 25 and hits the screening screen 24 to assist the self-cleaning of the screen mesh 24.

[0050] A rotating sleeve that is rotatably connected to the feed hopper 11 is fixedly connected to the rotating cylinder 21. The rotating cylinder 21 is rotated by setting a sprocket on the rotating sleeve in conjunction with a chain and a motor. The rotation of the calcining kiln body 1 adopts the existing rotary kiln drive rotation method. Support rod one and support rod two are fixedly connected to both sides of the L-shaped guide block 211. Support rod one is rotatably connected to the rotating sleeve, and support rod two is fixedly connected to the discharge cylinder 12.

[0051] Example 2: Please refer to Figure 10 As shown, the following solutions can be used to address the problem of lithium resources being lost due to the failure to specifically recover valuable components such as lithium vapor, resulting in the emission of lithium through exhaust gas.

[0052] In this embodiment, the recycling and purification mechanism 3 includes a purification cylinder 31. The interior of the purification cylinder 31 is divided into an upper purification chamber 32 and a lower recycling chamber 33 by a fixedly connected partition. A modified molecular sieve layer is installed in the lower recycling chamber 33. The modified molecular sieve layer is a 13X molecular sieve loaded with Al2O3. The 13X molecular sieve is used as the matrix, and an alumina coating or particles are loaded on its surface or in its pores. The exhaust gas physically adsorbs the lithium vapor contained in it through the van der Waals forces of the pores of the modified molecular sieve layer, thereby completing the recovery of lithium vapor.

[0053] An alkaline activated carbon layer is installed at the top of the upper purification chamber 32, and a calcium chloride solution is injected into the bottom of the upper purification chamber 32. The exhaust gas selectively adsorbs lithium vapor through the van der Waals forces of the modified molecular sieve layer, laying the foundation for subsequent lithium resource recovery. Then it enters the calcium chloride solution to remove fluoride, and the alkaline activated carbon layer adsorbs acidic gases, realizing the stepwise removal of pollutants in the exhaust gas and achieving multi-stage treatment of lithium recovery, fluoride removal, and acidic gas adsorption.

[0054] A suction pipe 34 is fixedly connected between the lower recovery chamber 33 and the discharge cylinder 12, and a negative pressure fan is installed on the suction pipe 34. Several through holes (not shown) are opened on the side wall of the rotating cylinder 21 to assist the rapid flow of tail gas in the calcining kiln 1 and achieve full purification of tail gas. A T-shaped pipe 35 communicating with the lower recovery chamber 33 is fixedly connected to the top of the partition. The liquid level of the calcium chloride solution is lower than the height of the T-shaped pipe 35, and several dispersion holes are opened on the outer wall of the end of the T-shaped pipe 35 to divert the tail gas introduced into the calcium chloride solution to enhance the fluoride removal effect.

[0055] The top of the purification cylinder 31 is equipped with an exhaust pipe. The calcination exhaust gas in the calcining kiln 1 is drawn into the lower recovery chamber 33 in the purification cylinder 31 by a negative pressure fan combined with the suction pipe 34. Then, it enters the calcium chloride solution in the upper purification chamber 32 through the T-shaped pipe 35 to remove fluorides. Subsequently, the acidic gas is adsorbed by alkaline activated carbon and then discharged from the purification cylinder 31 through the exhaust pipe.

[0056] On the purification cylinder 31, on both sides of the top and bottom of the modified molecular sieve layer, there are fixed and connected gas pipe 2 36 and gas pipe 1 37 respectively. A one-way valve is installed on gas pipe 1 37. Control valves are installed on gas pipe 2 36 and T-shaped pipe 35. A condenser 38 is installed on gas pipe 2 36. The control valve on T-shaped pipe 35 is closed and the control valve on gas pipe 2 36 is opened. High temperature inert nitrogen gas is injected into the lower recovery chamber 33 through gas pipe 1 37. The high temperature weakens the physical adsorption force, so that lithium element is desorbed from the surface of molecular sieve in the form of lithium dioxide vapor or lithium ions. Then, it enters the condenser 38 through gas pipe 2 36 with the nitrogen gas flow, condenses to form lithium solution and is collected and recovered.

[0057] Example 3: Please refer to Figures 1-10 As shown, this invention also proposes a high-temperature calcination process for lepidolite based on exhaust gas purification, comprising the following steps:

[0058] Step 1: The lithium mica is transported and calcined step by step using a screening and grading method: the calcining kiln body 1 and the rotating cylinder 21 rotate slowly at the same time in opposite directions. The burner heats the calcining kiln body 1. Multiple limiting plates 210 divide the outer wall of the rotating cylinder 21 into areas a, b, c, d, etc., from the feed hopper 11 to the discharge cylinder 12.

[0059] The lepidolite is fed into the calcining kiln body 1 through the feed hopper 11 and located outside the rotating cylinder 21. Combined with a set of limiting plates 210, the lepidolite is confined to area a. The rotating cylinder 21 carries two sets of shovel blocks 22 and rotates circumferentially. The lepidolite in the calcining kiln body 1 is shoveled through the feed trough 23 on the lowest shovel block 22. The lepidolite is shoveled into the rotating cylinder 21. During this process, the smaller lepidolite particles are screened into the feed trough 23 below the screen 24 by the screening screen 24. The small lepidolite particles are temporarily retained by the arc plate 26.

[0060] Large, unscreened lithium mica particles enter the rotating drum 21 and are quickly guided to the next set, the discharge port 29 in zone b, by the arc-shaped plate 26 and the Z-shaped baffles 28 on both sides of the feed chute 23 in zone a. They are then discharged back into the calcining kiln body 1. After the shovel block 22 rotates from its lowest point to its highest point, the elastic rod 27 on the arc-shaped plate 26 abuts against the stop rod 213 on the L-shaped guide block 211, thus restricting the synchronous rotation of the arc-shaped plate 26 and causing the compression spring 25 of the arc-shaped plate 26 to contract. Small lithium mica particles between the screening screen 24 and the feed trough 23 are fed into the arc-shaped trough and then into the guide trough 212 in area a on the L-shaped guide block 211. They are then guided to the discharge port 29 in area b, which cooperates with another set of shovel blocks 22, and discharged into the calcining kiln body 1 again. As the rotating cylinder 21 rotates, the elastic rod 27 deforms and separates from the stop rod 213. The arc-shaped plate 26 resets under the compression force of the spring 25 and impacts the screening screen 24, assisting in the self-cleaning of the screen 24 mesh.

[0061] Through the rotation of two sets of shovel blocks 22, lepidolite is conveyed and processed step by step in areas a, b, c, d, etc. outside the rotating cylinder 21. Combined with the external control system to control the rotation speed of the calcining kiln 1 and the rotating cylinder 21, the precise passage time of lepidolite in the calcining kiln 1 is ensured, avoiding the phenomenon of some lepidolite being discharged too slowly or too quickly, resulting in local over-burning or incomplete calcination. By adopting an interval calcination treatment method for lepidolite, the calcination interval time of small lepidolite particles is further extended compared to large lepidolite particles, avoiding the phenomenon of over-calcination of small lepidolite particles. The calcined lepidolite is discharged through the discharge cylinder 12.

[0062] Step 2: Multi-stage purification treatment of calcination tail gas: The calcination tail gas in the calcination kiln 1 is drawn into the lower recovery chamber 33 in the purification cylinder 31 by a negative pressure fan and suction pipe 34. The tail gas first undergoes physical adsorption of lithium vapor by van der Waals forces in the pores of the modified molecular sieve layer, and then enters the calcium chloride solution in the upper purification chamber 32 through T-tube 35 to remove fluoride. Subsequently, acidic gases are adsorbed by alkaline activated carbon to complete the purification and recovery treatment of the tail gas.

[0063] Step 3: Lithium recovery process: Close the control valve on T-tube 35 and open the control valve on gas pipe 2 36. Inject high-temperature inert nitrogen gas into the lower recovery chamber 33 through gas pipe 1 37. The high temperature weakens the physical adsorption force, causing lithium elements to be desorbed from the surface of the molecular sieve in the form of lithium dioxide vapor or lithium ions. Then, the lithium is flowed through gas pipe 2 36 with the nitrogen gas and enters the condenser 38, where it is condensed to form a lithium solution and collected for recovery.

[0064] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-temperature calcination device for lithium mica based on exhaust gas purification, comprising a calcination kiln body (1), characterized in that, A burner is rotatably installed on the annular outer wall of the calcining kiln body (1), and a feed hopper (11) and a discharge cylinder (12) are rotatably connected at both ends of the calcining kiln body (1). The interior of the calcining kiln body (1) is provided with a conveying and screening mechanism (2) for graded calcination of lepidolite. A recovery and purification mechanism (3) for multi-stage treatment of calcination tail gas is provided on one side of the calcining kiln body (1).

2. The lithium mica high-temperature calcination device based on tail gas purification treatment according to claim 1, characterized in that, The material conveying and screening mechanism (2) includes a rotating cylinder (21) located inside the calcining kiln body (1) and coaxially arranged therewith. Two sets of shovel blocks (22) that are slidably connected to the inner wall of the calcining kiln body (1) are fixedly connected to the outer wall of the rotating cylinder (21). Several feed troughs (23) that penetrate into the rotating cylinder (21) are equidistantly opened on the shovel blocks (22) along their length direction. A screening screen (24) is fixedly connected inside the feed troughs (23).

3. The lithium mica high-temperature calcination device based on exhaust gas purification treatment according to claim 2, characterized in that, The inner wall of the rotating cylinder (21) is provided with an arc-shaped groove, and an arc-shaped plate (26) is fixedly connected to the arc-shaped groove by several springs (25). One side of the arc-shaped plate (26) abuts against the screening screen (24). An elastic rod (27) is fixedly connected to the concave side of the arc-shaped plate (26). The inner wall of the rotating cylinder (21) is provided with a slot for the elastic rod (27) to pass through and slide.

4. The lithium mica high-temperature calcination device based on exhaust gas purification treatment according to claim 2, characterized in that, Multiple Z-shaped baffles (28) are fixedly connected to the inner wall of the rotating cylinder (21). The feed trough (23) is located between two adjacent sets of Z-shaped baffles (28), and a discharge port (29) penetrating the side wall of the rotating cylinder (21) is opened between the free ends of the two adjacent sets of Z-shaped baffles (28). A limiting plate (210) is fixedly connected between the two sets of shovel blocks (22) and on the side of the corresponding feed trough (23) away from the feed hopper (11).

5. The lithium mica high-temperature calcination device based on exhaust gas purification treatment according to claim 3, characterized in that, The rotating cylinder (21) is provided with an L-shaped guide block (211) inside. The L-shaped guide block (211) has several L-shaped guide grooves (212) evenly spaced along its length. Both sides of the L-shaped guide block (211) are equipped with stop bars (213) that cooperate with the elastic rod (27).

6. The high-temperature calcination device for lithium mica based on exhaust gas purification treatment according to claim 5, characterized in that, The rotating cylinder (21) is fixedly connected to a rotating sleeve that is rotatably connected to the feed hopper (11). The two sides of the L-shaped guide block (211) are respectively fixedly connected to a support rod one and a support rod two. The support rod one is rotatably connected to the rotating sleeve, and the support rod two is fixedly connected to the discharge cylinder (12).

7. The high-temperature calcination device for lithium mica based on tail gas purification treatment according to claim 1, characterized in that, The recycling and purification mechanism (3) includes a purification cylinder (31). The interior of the purification cylinder (31) is divided into an upper purification chamber (32) and a lower recycling chamber (33) by a fixedly connected partition. A modified molecular sieve layer is installed in the lower recycling chamber (33). An alkaline activated carbon layer is installed at the top of the upper purification chamber (32), and a calcium chloride solution is injected into the bottom of the upper purification chamber (32).

8. The high-temperature calcination device for lithium mica based on exhaust gas purification treatment according to claim 7, characterized in that, A suction pipe (34) is fixedly connected between the lower recovery chamber (33) and the discharge cylinder (12), and a negative pressure fan is installed on the suction pipe (34). A T-shaped pipe (35) communicating with the lower recovery chamber (33) is fixedly connected to the top of the partition, and several dispersion holes are opened on the outer wall of the end of the T-shaped pipe (35). An exhaust pipe is installed on the top of the purification cylinder (31).

9. The high-temperature calcination device for lithium mica based on tail gas purification treatment according to claim 8, characterized in that, The purification cylinder (31) is fixedly connected to the top and bottom sides of the modified molecular sieve layer by the second gas pipe (36) and the first gas pipe (37). A one-way valve is installed on the first gas pipe (37). Control valves are installed on the second gas pipe (36) and the T-tube (35). A condenser (38) is installed on the second gas pipe (36).

10. A high-temperature calcination process for lepidolite based on exhaust gas purification, characterized in that, Includes the following steps: S1: The calcination process of lepidolite is carried out by screening and grading: the calcination kiln (1) and the rotating cylinder (21) rotate slowly at the same time and in opposite directions. When the material is rotated to the lowest point, the feed chute (23) of the shovel block (22) shovels the lepidolite in the calcination kiln (1) into the rotating cylinder (21). The screening screen (24) screens and retains small particles of lepidolite until it is raised to the highest point and then discharged into the calcination kiln (1). Large particles of lepidolite that do not pass the screening are discharged into the calcination kiln (1) again and quickly for differentiated interval calcination treatment, avoiding the phenomenon of over-calcination of small particles of lepidolite while avoiding the incomplete calcination of large particles of lepidolite. S2: Multi-stage purification treatment of calcination tail gas: The tail gas first passes through a modified molecular sieve layer to physically adsorb lithium vapor, then passes through a calcium chloride solution to remove fluoride, and then passes through alkaline activated carbon to adsorb acidic gases, thus completing the purification treatment of the tail gas. S3: Lithium recovery process: High-temperature inert nitrogen gas is introduced into the modified molecular sieve layer to weaken the physical adsorption force, so that lithium elements are desorbed from the surface of the molecular sieve in the form of lithium dioxide vapor or lithium ions, and then condensed in the condenser (38) with the nitrogen gas flow to form a lithium solution for recycling.

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