Dry Processing Technology for Particle Structure Control

Abstract

Background and Aims: Powder materials are extensively utilized not only as final products in foods, cosmetics, and pharmaceuticals but also as raw materials and intermediates in the manufacturing processes of various industrial products including battery materials and magnetic materials. Powder consists of an aggregate of solid particles, and controlling the structure of powder, such as particle dispersion state and granulation structure, is essential for material development and manufacturing. While wet grinding can achieve sub-micron particle sizes, it requires additional drying processes and wastewater treatment, making dry processing more economical for industrial-scale production. Recent advances in high-performance classifiers have enabled dry grinding to produce finer particles, and dry composite processing has emerged as an energy-saving and environmentally friendly method. This study aims to introduce examples of particle structure control through dry operations, focusing on particle size reduction and composite processing using our equipment.

Methods and Results: Three main dry processing technologies were investigated: fine grinding, high-speed classification, and dry composite processing. For fine grinding, Pulvis^®, a dry-type agitating media mill with an integrated classifier, successfully produced sub-micron silica particles by combining grinding and classification operations. High-speed classifiers mounted on jet mills achieved average particle sizes of approximately 0.5 μm with maximum particle sizes around 2 μm for silica grinding. Opposed jet mill AFG demonstrated effective disintegration of agglomerated particles while minimizing contamination and controlling fine particle generation through gas pressure adjustment. For composite processing, Nobilta^® dry particle composer was applied to battery materials and pharmaceuticals. In battery applications, silicon particles were surface-modified with solid electrolyte coatings, creating microporous structures that reduced volume changes during charge-discharge cycles. In pharmaceutical applications, mannitol granules were composited with finely ground ibuprofen, and dissolution behavior was controlled through surface coating with hardened castor oil powder.

Conclusions (Outlooks): This study demonstrates that dry processing operations offer significant advantages over wet methods, including elimination of binder requirements, no need for drying processes, and overall energy savings in manufacturing processes. The combination of advanced grinding equipment with high-performance classifiers enables continuous and efficient production of sub-micron particles while preventing reagglomeration. Dry composite processing proves particularly valuable for battery materials requiring high charge-discharge rates and pharmaceutical applications demanding controlled dissolution behavior. The binder-free nature of dry processing makes it especially suitable for battery material development, where contamination control is critical. As global demand for automotive battery materials continues to grow and pharmaceutical industries face increasing numbers of poorly soluble drugs, dry processing technologies are expected to find expanded applications. Future development efforts will focus on further improving the performance of dry processing equipment to meet evolving industrial requirements for advanced functional materials.