Continuous washing, filtering and drying device for producing lithium bis (fluorosulfonyl) imide

Abstract

A continuous washing, filtering and drying device for production of lithium bis (fluorosulfonyl) imide is characterized in that a pressurized rotary drum filter, a spiral conveyor and a vacuum belt dryer are arranged, the pressurized rotary drum filter is divided into a filtering area, a washing area and a drying area, a DMC organic solvent is adopted as a washing solution, hot air is heated by nitrogen and then circularly blows air, and the drying effect is achieved. The whole system is in a sealed state, pressure filtration can be realized, the filtration efficiency is greatly improved, and the water content of discharged materials can be controlled within 5%; then, the materials enter a double-layer discharging device through a filtering stock bin and a spiral conveyor, and then enter a vacuum belt type drying machine to be finally dried; the belt dryer can realize multi-stage temperature section heating and drying, so that stepped heating is realized; the whole process can realize continuous operation under the condition of strict sealing, manual operation and manual transfer of semi-finished product materials between production units are reduced, the production stability is improved, and the problem of large-scale production of LiFSI is solved.

Description

Technical Field

[0001] The utility model belongs to the technical field of chemical equipment, and particularly relates to a continuous washing, filtering and drying device for producing lithium bis(fluorosulfonyl)imide. Background Art

[0002] Lithium bis(fluorosulfonyl)imide is an important lithium salt, which is widely used in various chemical synthesis fields. With the continuous development of the new energy vehicle industry, the market prospect of lithium bis(fluorosulfonyl)imide is very broad.

[0003] The English name of lithium bis(fluorosulfonyl)imide is LiFSI, and its chemical formula is F2NO4S2.Li. As an additive to battery materials, it can improve the energy density and cycle life of the battery, while also reducing the internal resistance of the battery and improving the rate performance of the battery. Therefore, in the context of the development of the new energy vehicle industry, the demand for lithium bis(fluorosulfonyl)imide continues to increase. Due to its good high temperature resistance (it can remain stable at temperatures below 200°C), good low temperature performance, not easy to hydrolyze and more environmentally friendly performance characteristics, lithium bis(fluorosulfonyl)imide can be used as a next-generation secondary lithium-ion battery electrolyte lithium salt to replace lithium hexafluorophosphate. The development prospects are very broad. Due to the outstanding characteristics of lithium bis(fluorosulfonyl)imide such as heat sensitivity and hydrophilicity in the production process, the equipment widely used in the industry, such as cone, centrifuge filtration, and double cone drying filtration, is difficult to meet the production process requirements and large-scale production. This results in high production costs, unstable product quality, and difficulty in large-scale production.

[0004] The utility model with announcement number CN215352323U discloses a filtration device for purifying lithium bis(fluorosulfonyl)imide filtrate, and its technical scheme includes a filter box, wherein a primary filter chamber and a secondary filter chamber are sequentially arranged inside the filter box from top to bottom, and a filter cartridge is vertically arranged inside the primary filter chamber. By arranging the primary filter chamber and the secondary filter chamber, the lithium bis(fluorosulfonyl)imide filtrate is double-filtered by using the filter cartridge and a solid-liquid separator, wherein the solid filtered by the filter cartridge is retained in the filter cartridge, and the liquid is discharged from a drain pipe. When the material inside the filter cartridge reaches a set height, the feed valve is closed to allow the material in the primary filter chamber to be fully filtered, and then the switch valve on the discharge pipe is opened, and then the solid-liquid separator is opened to perform solid-liquid separation on the filtered material, and the lithium bis(fluorosulfonyl)imide filtrate in the filtered material is recovered. Although it reduces the loss of raw materials in the lithium bis(fluorosulfonyl)imide vegetation process, it still cannot meet large-scale production.

[0005] The invention with announcement number CN115155151A discloses a drying system and drying method for crystalline lithium salt, and its technical scheme includes a dryer and more than two filters, each filter performs filter pressing on the crystalline lithium salt mother liquor and supplies it to the dryer; the dryer receives the crystalline lithium salt after filter pressing from each filter, dries the crystalline lithium salt, and transports the dried crystalline lithium salt to the next process device; each filter alternately performs filter pressing on the crystalline lithium salt mother liquor and alternately supplies the filtered crystalline lithium salt to the dryer. Although the drying system and drying method of the crystalline lithium salt can make the entire drying process of the crystalline lithium salt continuous, the drying effect of the drying device needs to be improved, and the structure of the drying and filtering still needs to be improved. Summary of the invention

[0006] The purpose of the utility model is to provide a continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide in view of the deficiencies of the above-mentioned prior art, so as to realize continuous production operation and large-scale production and reduce production costs.

[0007] In order to solve the above technical problems, the technical solution adopted by the utility model is:

[0008] A continuous washing, filtering and drying device for producing lithium bis(fluorosulfonyl)imide, comprising a pressurized drum filter and a screw conveyor connected to the pressurized drum filter via a transition silo, wherein the outlet of the screw conveyor is connected to a first double-layer discharge device for sealed discharge, and the outlet of the first double-layer discharge device leads to a vacuum belt dryer;

[0009] The vacuum belt dryer is provided with multiple layers of conveyor belts and a heating device is provided under each layer of conveyor belts, and the conveyor belts are heated sequentially from top to bottom, and the discharge port of the vacuum belt dryer is connected to the second double-layer unloading device for sealed discharge.

[0010] The pressure drum filter comprises a filtering area, a washing area and a preliminary drying area which are arranged in sequence;

[0011] The 48°±5° area is set as the filtering area.

[0012] The 144°±5° area is set as the washing area.

[0013] The 96°±5° area is set as the preliminary drying section.

[0014] The other areas are set as discharging areas, and each area is sealed with isolation parts.

[0015] The vacuum belt dryer is provided with three layers, and the temperature of the first layer is set at 15-25°C from top to bottom, the second layer is set at 30-40°C, and the third layer is set at 50-60°C.

[0016] The temperature of the first layer was set at 20°C, the second layer was set at 35°C, and the third layer was set at 55°C.

[0017] The first double-layer unloading device and the second double-layer unloading device are both provided with double-layer unloading valves.

[0018] The washing area is provided with three chambers, and the first stage uses the filtrate of the second washing stage, the second stage uses the filtrate of the third washing stage, and the third washing stage uses fresh dichloroethane (99.99%, water ≤0.005%) washing liquid.

[0019] The temperature of the preliminary drying section is not higher than 20°C.

[0020] The washing liquid in the washing zone adopts DMC organic solvent.

[0021] The beneficial effects of the utility model are:

[0022] (1) The continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide is provided with a pressurized drum filter, a screw conveyor and a vacuum belt dryer. The mother liquor of LiFSI crystallization starts from the pressurized drum filter, which is divided into a filtering area, a washing area and a drying area. The washing liquid adopts DMC organic solvent, and the hot air is heated by nitrogen and then circulated. The whole system is in a sealed state, which can realize pressurized filtration, greatly improve the filtration efficiency, and the moisture content of the discharge material can be controlled within 5%. Then the material passes through the filter silo and the screw conveyor into the double-layer unloading device, and then enters the vacuum belt dryer for final drying. The belt dryer can realize multi-stage temperature section heating and drying, and realize step heating. After the final drying is completed, it enters the double-layer unloading device for packaging to obtain the finished product. The whole process can realize continuous operation under strict sealing, reduce manual operation and manual transfer of semi-finished materials between production units, improve production stability, and solve the problem of large-scale production of LiFSI.

[0023] (2) Compared with centrifuge filtration, double cone drying, spiral drying, disc drying, etc., the continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide can shorten the drying time to 4 hours. The drying is uniform and efficient, and it is not easy to agglomerate. The traditional method takes more than 20 hours to dry, which is easy to agglomerate. In addition, the traditional method equipment has dead corners and is prone to material accumulation. If the accumulated material cannot be cleaned for a long time, it will deteriorate and affect the product quality. The present filtering and drying device adopts a vacuum belt dryer, which has no dead corners and is not easy to accumulate material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of the utility model;

[0025] Figure 2 It is a structural diagram of a pressure drum filter. DETAILED DESCRIPTION

[0026] The following is a description of the implementation of the present invention by means of specific embodiments. People familiar with the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification.

[0027] The utility model provides a continuous washing, filtering and drying device for producing lithium bis(fluorosulfonyl)imide. Figure 1 and Figure 2 shown.

[0028] A continuous washing, filtering and drying device for producing lithium bis(fluorosulfonyl)imide comprises a pressurized drum filter 1 and a screw conveyor 3 connected to the pressurized drum filter 1 by a transition silo 2, wherein the outlet of the screw conveyor 3 is connected to a first double-layer discharge device 4 for sealed discharge, and the outlet of the first double-layer discharge device 4 leads to a vacuum belt dryer 5.

[0029] The vacuum belt dryer 5 is provided with multiple layers of conveyor belts and a heating device is provided under each layer of conveyor belts, and the conveyor belts are heated sequentially from top to bottom, and the discharge port of the vacuum belt dryer 5 is connected to the second double-layer unloading device 6 for sealed discharge.

[0030] The pressurized drum filter 1 includes a filtering area, a washing area and a preliminary drying area arranged in sequence; the 48°±5° area is set as the filtering area; the 144°±5° area is set as the washing area, the washing area has three chambers, and the first stage uses the filtrate of the second washing section, the second stage uses the filtrate of the third washing section, and the third washing section uses fresh dichloroethane (99.99%, water ≤0.005%) washing liquid; the 96°±5° area is set as the preliminary drying section, and the temperature of the preliminary drying section is not higher than 20°C. The other areas are set as the discharge area, and each area is sealed with an isolation piece. Among them, Figure 2 The internal structure diagram of the pressurized drum filter, A1 is the slurry inlet, A2 is the first washing liquid inlet, A3 is the second washing liquid inlet, A4 is the third washing liquid inlet, A5 is the drying air inlet, A7 / 1... A7 / 6 is the isolation plate high pressure gas interface, A8 is the filter cloth cleaning liquid inlet, A9 is the filter cake unloading nitrogen backflush, A10 is the nitrogen backflush during filter cloth washing, A11 is the residual liquid emptying port in the filtrate tube; and B1 is the mother liquor outlet, B2 is the first washing liquid outlet, B3 is the second washing liquid outlet, B4 is the third washing liquid outlet, B5 / 1 and B5 / 2 are the drying air outlets, B7 is the filter cloth washing liquid outlet, B8 / 1 and B8 / 2 are the closed bearing frame drainage ports, B9 is the filter cake unloading port, and B10 is the backflush nitrogen back nitrogen device during filter cake unloading. In this embodiment, the washing liquid in the washing zone adopts DMC organic solvent.

[0031] The vacuum belt dryer 5 has three layers, two layers of partitions are provided, a heating device is provided under the conveyor belt, and the radial space is divided into three layers: upper, middle and lower. From top to bottom, the temperature of the first layer is set to 15-25° C., the second layer is set to 30-40° C., and the third layer is set to 50-60° C. In this embodiment, the temperature of the first layer is set to 20° C., the second layer is set to 35° C., and the third layer is set to 55° C.

[0032] In order to facilitate the control of material inlet and outlet, double-layer discharge valves are provided on the first double-layer discharge device and the second double-layer discharge device. The double-layer discharge valves can realize the sealed environment transfer of materials between the discharge of the screw conveyor 3 and the vacuum belt dryer 5. When the spiral discharges, the middle valve of the double-layer discharge device is closed. When the material enters the vacuum belt dryer 5, the upper valve is closed and the lower valve is interlocked and opened. The finished product discharge principle is the same, realizing the sealed environment transfer of materials so that the connected equipment does not affect each other.

[0033] During operation, the LiFSI crystallization mother liquor material is filtered through the inlet of the pressurized drum filtration area, and enters the washing area after the drum rotates. The washing area is divided into multiple stages for washing, which can improve the washing effect; then it enters the drying area, and the drying area is connected to a nitrogen hot air device for preliminary drying; after preliminary drying, the material enters the screw conveyor through the transition silo, and the outlet of the screw conveyor is connected to a double-layer unloading device to realize the unloading in a sealed environment of the system, and then enters the belt dryer for final drying of the finished product; and the dryer discharge port is connected to a double-layer unloading device to realize the sealed unloading of the system. The entire process can achieve continuous operation under strict sealing conditions, reducing manual operations and manual transfer of semi-finished materials between production units, improving production stability, and solving the problem of large-scale production of LiFSI.

[0034] Compared with centrifuge filtration, double cone drying, spiral drying, disc drying and the like, the continuous washing, filtering and drying device for lithium bis(fluorosulfonyl)imide production can shorten the drying time to 4 hours, has high drying efficiency and is not prone to agglomeration. The traditional method takes more than 20 hours to dry and is prone to agglomeration. In addition, the traditional method equipment has dead corners and is prone to material accumulation. If the accumulated material cannot be cleaned for a long time, it will deteriorate and affect the product quality. The present filtering and drying device adopts a vacuum belt dryer, which has no dead corners and is not prone to material accumulation.

[0035] Compared with the same amount of filter cakes, the moisture content of the centrifuge and cone filtration currently used in the industry is 20%, which makes it difficult to achieve pressurized filtration and washing, and has low production efficiency; the time from feeding to filter cake discharge is as long as more than 12 hours; while the use of this drying device reduces the moisture content by 75% and increases the production efficiency by nearly 300 times.

[0036] If the words "first", "second" and so on are used in this patent to limit components, those skilled in the art should know that the use of "first" and "second" is only for the convenience of describing the utility model and simplifying the description, and the above words have no special meaning.

[0037] The above shows and describes the basic principle, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited by the above embodiments. The above embodiments and descriptions are only for explaining the principle of the utility model. The utility model may have various changes and improvements without departing from the spirit and scope of the utility model. These changes and improvements fall within the scope of the utility model to be protected. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

[0038] In the description of the present invention, it is necessary to understand that the terms "front", "rear", "left", "right", "center", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the protection content of the present invention.

Claims

1. A continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide, characterized in that: It includes a pressurized drum filter and a screw conveyor connected to the pressurized drum filter through a transition silo, and the outlet of the screw conveyor is connected to a first double-layer discharge device for sealed discharge, and the outlet of the first double-layer discharge device leads to a vacuum belt dryer; The vacuum belt dryer is provided with multiple layers of conveyor belts and a heating device is provided under each layer of conveyor belts, and the conveyor belts are heated sequentially from top to bottom, and the discharge port of the vacuum belt dryer is connected to the second double-layer unloading device for sealed discharge.

2. A continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The pressure drum filter comprises a filtering area, a washing area and a preliminary drying area which are arranged in sequence; The 48°±5° area is set as the filtering area. The 144°±5° area is set as the washing area. The 96°±5° area is set as the preliminary drying section. The other areas are set as discharging areas, and each area is sealed with isolation parts.

3. A continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The vacuum belt dryer is provided with three layers.

4. A continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide according to claim 1, characterized in that: The first double-layer unloading device and the second double-layer unloading device are both provided with double-layer unloading valves.

5. A continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide according to claim 2, characterized in that: The washing area is provided with three chambers, and the first stage uses the filtrate of the second washing stage, the second stage uses the filtrate of the third washing stage, and the third washing stage uses fresh dichloroethane washing liquid.

6. A continuous washing, filtering and drying device for the production of lithium bis(fluorosulfonyl)imide according to claim 2, characterized in that: The washing liquid in the washing zone adopts DMC organic solvent.

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