How to choose the drying process and drying equipment for 903242 battery pack ternary materials

Usually, the washed ternary material precursor filter cake contains 10%~50% moisture, which needs to be removed for use in subsequent processes. Drying is the process of removing moisture from solid materials by vaporizing the moisture or other solvents in solid materials by heating. The drying process is very complicated, involving three basic theories of fluid mechanics, heat transfer, and mass transfer. 1. Drying process The drying process includes the determination of drying time, drying temperature, and drying atmosphere. The ternary material precursor is a low-valent compound of variable-valent metals, which will be oxidized in the air, and the higher the drying temperature, the more severe the oxidation. However, due to the high cost and low drying efficiency of vacuum drying and inert atmosphere protection drying, the quality of the precursor dried at an appropriate temperature in an air atmosphere can basically meet the requirements, so air atmosphere drying is generally selected.

XRD graph of ternary precursor after treatment at different drying temperatures From the figure, it can be seen that the XRD spectrum of the precursor after treatment at 150℃ and the XRD spectrum of the vacuum treatment at 100℃ have obvious differences, so the drying temperature of the precursor filter cake in the air should be less than 150℃. When the temperature reaches 400℃, the precursor will be oxidized into trivalent oxides. The total metal content of the precursor at different drying temperatures increases with the increase of drying temperature, and the specific surface area suddenly increases after 200℃.

Total metal content and specific surface area of the precursor at different drying temperatures When it is determined that the drying temperature of the precursor cannot be higher than 150℃, the drying time required for different drying equipment is different according to the drying efficiency of the drying equipment and the moisture control standard of the precursor is less than 1%. 2. Drying equipment According to different conduction methods, drying can be divided into conduction drying, convection drying, radiation drying, dielectric drying and combined drying. When choosing a dryer for ternary material precursors, at least the following points need to be considered: the moisture content requirements of the product; the moisture content of the filter cake and whether the moisture content of the filter cake is uniform; the production capacity of the dryer, the feeding method of the material; the material of the part of the dryer in contact with the ternary material precursor needs to be alkali-resistant and cannot bring in metal impurities or other impurities; the drying temperature that needs to be achieved, etc. The drying of ternary material precursors can be carried out by hot air circulation ovens, rotary dryers, disc dryers, rake dryers, microwave dryers, etc. 1 Hot air circulation oven The hot air circulation oven looks like a box, and the outer wall is an insulating layer.

Internal structure diagram of hot air circulation oven 1 casters 2 thermocouples 3 control panel 4 insulation shell 5 fan 6 exhaust port 7 heating wire 8 tray 9 tray bracket The circulating hot air generated by the fan blows to the surface of the wet material to achieve the purpose of drying, and the hot air circulates through the material repeatedly. Advantages: easy loading and unloading, small material loss, and easy cleaning of the tray. Therefore, for products that need to be frequently replaced, high-priced finished products or small batches of materials, the advantages of the box dryer are very significant. The disadvantages are: the material cannot be dispersed, the drying is uneven, and the drying time is long; loading and unloading materials is time-consuming and labor-intensive, the labor intensity is high, and the equipment utilization rate is low; dust is flying when unloading materials, and the environmental pollution is serious; the thermal efficiency is low, generally around 40%, and about 2.5 kg of heating steam is consumed for every 1 kg of moisture dried. 2 Rotary Drum Dryer The main body of the rotary drum dryer is a slightly inclined and rotating cylinder.

Advantages: large production capacity and continuous operation; wide range of applications, can be used to dry granular materials, and is also beneficial for those materials with high adhesion; easy to clean. Disadvantages: high price; difficult to install and disassemble; low thermal efficiency; large difference in residence time between material particles, so it is not suitable for materials with strict temperature requirements. 3 Disc continuous dryer

Structural diagram of disc dryer 1 Thermal oil tank 2 Hot oil pump 3 Stop valve 4 Thermometer 5 Continuous dryer 6 Feed port 7 Exhaust port 8 Scraper 9 Heating plate 10 Reducer 11 Feed port 12 Legs The hollow heating plate is the main component of the dryer. Baffles or short tubes are welded inside it in a certain arrangement. On the one hand, the disturbance of the heating medium in the hollow plate is increased, and the heat transfer effect is improved; on the other hand, the rigidity of the hollow plate is increased and its carrying capacity is improved. Each heating plate has an inlet and outlet pipe for the heat carrier. A certain distance is maintained between each layer of heating plates, which are fixed horizontally on the frame. Features: high thermal efficiency, low energy consumption, short drying time; good controllability; the dried material is not easy to be damaged; clean environment, etc. Note: The filter cake of the ternary material precursor filtered by the plate and frame filter press has a high moisture content and belongs to a paste material, so the disc dryer cannot be used. Therefore, if the dryer chooses disc drying, the front-end filtering and washing equipment needs to choose a centrifuge. 4 Belt dryer Belt dryer is a high-conductivity dryer with continuous vacuum. According to the material drying process, multiple layers of drying belts can be set. The temperature is 40~180℃ and the running speed can be adjusted.

Belt dryer structure diagram 1 heat medium inlet 2 shell 3 baffle plate 4 transmission shaft 5 heating plate 6 guide belt 7 feed port 8 feed valve 9 vacuum tube 10 drain port 11 discharge valve 12 hot coal outlet Features: Continuous feeding and discharging under vacuum drying; high product yield; product drying chamber does not contact with metal objects, and the morphology is not damaged after drying; product drying process is easy to optimize and has strong adjustability; low energy consumption; suitable for large-scale continuous automatic production.

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