Recycled Cathode Material Entering the Supply Stream
Recycled cathode precursors match virgin cell performance when hydrometallurgical refining limits trace iron and copper contaminants below 10 and 5 ppm respectively.
Jet Milling
Meaning
This high-energy particle size reduction process utilizes high-velocity gas streams to collide powder particles against each other within a grinding chamber. In the production of cathode materials, jet milling reduces the size of synthesized active material agglomerates to the targeted micrometric distribution. This term governs the physical dimension and surface area of the processed powder, ending when the particles escape through the centrifugal classifier or the gas flow is shut down.
This operation does not apply to wet ball milling or media-based grinding where grinding media introduce contamination risks.
Process Operation
The powder enters the grinding chamber through a venturi feeder where it meets high-pressure nitrogen or dry air streams. These gas streams create a high-speed vortex that forces the particles to collide with one another at high speeds. This autogenous grinding process breaks down the agglomerates without using grinding media, eliminating the risk of metallic contamination from steel or ceramic balls.
As the particles break apart, a centrifugal classifier at the top of the chamber separates the fine particles from the larger ones. The fine particles are carried out of the mill by the gas flow, while the larger particles return to the grinding zone for further milling.
Particle Optimization
Sourcing departments specify the desired particle size distribution and surface area of the milled powder to ensure optimal slurry properties. Proper size reduction improves the packing density of the electrode and ensures uniform lithium-ion transport during operation. Excessive milling can create too many fine particles, which increases the surface area and leads to undesirable side reactions with the electrolyte.
The process must be carefully controlled to achieve the perfect balance between particle size and surface area. Consistent milling performance is critical for producing high-quality cathode active materials.
Equipment Economics
Sourcing managers evaluate the operating costs of this process, which are dominated by the energy required to compress the gas. Utilizing nitrogen gas instead of air prevents moisture absorption and oxidation of sensitive cathode materials, but increases the gas cost. The wear-resistant liners of the milling chamber must be inspected regularly to prevent contamination of the product.
High-efficiency classifiers and advanced nozzle designs help minimize energy consumption while maintaining high throughput. Selecting suppliers with modern milling technology ensures stable particle quality at a competitive processing cost.