When you plan to set up a lab-scale, pilot or commercial LFP plant, you are wondering what equipments/machines you need to buy and set up. But it needs to fit with your LFP cathode synthesis process. 90% of mainstream enterprises in China use the solid phase process to manufacture LFP cathode materials, of course it needs a liquid phase to synthesize the LFP precursor--FP (anhydrous iron phosphate ）first which we will post separately.
The figure below shows the process flow diagram for the preparation of lithium iron phosphate. A certain amount of anhydrous iron phosphate, lithium carbonate and organic carbon source in a certain amount of deionized water is fully mixed, through the sand mill grinding to make the slurry particle size to meet the requirements, and then spray-drying, the powdered material is loaded into the sagger and then roasted in a high-temperature nitrogen atmosphere furnace to get the lithium iron phosphate material, followed by airflow crushing, sieving, demagnetization, mixing and packaging into the warehouse.
The specific process is as follows:
(1) Batching and mixing: through the automatic weighing or metering system will be iron phosphate, lithium carbonate, glucose, deionized water, etc. in accordance with the set proportion of pipeline to the batching kettle mixing.
(2) Sand grinding: the mixed slurry will be transferred to the sand mill into the coarse grinding of about one micron, and then transferred to the next level of sand mill grinding again about 300 nanometers.
(3) Spray drying: the slurry will be ground to the requirements of the conveyor to the spray drying equipment, slurry in the water in a very short period of time to evaporate quickly, the raw material mixture is dried into semi-finished products powder.
(4) High temperature sintering: the use of automatic loading system, the spray-dried powder in a high-temperature furnace filled with nitrogen roasting, in the roasting process, the trivalent iron is reduced to divalent iron and lithium to form lithium ferrous phosphate, part of the decomposition of the organic carbon source into gas from the top of the furnace, a small portion of the decomposition of carbon coated with lithium iron phosphate particles on the surface, to get the lithium iron phosphate material. The main chemical reaction formula is as follows:
FePO4 +Li2CO3 +C6H12O6 LiFePO4 +CO+CO2 +H2O
(5) Jet pulverization: the roasted material is transported to the fluidized bed type airflow pulverizer through the airflow, the compressed air is accelerated by the four Rafael nozzles around the pulverization chamber to form a supersonic airflow, in the pulverization area, the material is crushed by collision with each other. Crushed material is sent to the rising airflow to the grading area, grading wheel rotating at high speed, qualified fine powder with the airflow into the cyclone dust collector, bag filter collection, did not reach the fineness of the coarse powder back to the crushing area to continue to crush.
(6) Mixing and sieving demagnetization: the material will pass through the sieving machine, electromagnetic iron remover, in order to remove the magnetic impurities in the product.
(7) Packaging and storage: lithium iron phosphate products through the automatic packaging machine in the vacuum packaging, packaging process in the temperature-controlled dehumidification packaging workshop room.