Size classification is a fundamental operation in powder processing. The technical group of classification and sieving is one of the oldest groups in APPIE, which started activities in 1973, 2 years after APPIE’s establishment.
Recently, with the development of application for nano-sized particles, there is the demand for classification of small cut size and fairly high precision. Especially, the classification with high precision in a wide range from 1 to 50 micron is needed for many industrial applications. Moreover, there has been considerable interest in the classification technology for nanoparticles with cut sizes from 20 to 500 nm. The aim of our activities is to study latest problems and information about those topics.
Current level of technology,trend and activities in future
- Recently, downsizing, high power, large capacity and enhanced safety are requested in the high-tech areas such as battery and semiconductor. Corresponding to these trends, needs of micro-scale separation and high accuracy are growing.
- Particularly in the field of electronic parts, high demand is number-base classification which separates ceramic and metal powders of the size from sub-micron to single-micron. Those powders are cohesive and adhesive.
- The important issue in dry classification is accurate control of classification of sub-micron powders. Study is made on semi free vortex classifiers such as cyclone separator. It is studied how to enhance separation efficiency and how to prevent adhesion of particles on the wall. Compact cyclone separators with high performance are commercialized as vacuum cleaners for home use. Further grade-up is expected for these machines.
- In wet classification, classification with cut-size from 20 nm to 500 nm draw the highest attention. The accurate water sieve (sedimentation method) making use of electric field is studied in the nano-size classification. Development of classifiers which keep high accuracy even in large particle concentration is demanded.
- Surface treatment of mesh and use of super-sonic is proposed to enable sieve classification to be applied to cohesive and adhesive powders. These methods are confirmed to be effective for practical use. Durability of mesh, applicability of sieve to finer powders and large capacity are important issues.
|Coordinator||Hiroshima University, Graduate School of Engineering, Department of Chemical Engineering||YOSHIDA/Hideto|
|Representative Organizer||NISSHIN ENGINEERING INC.||AKIYAMA/Satoshi|
|Vice Representative Organizer||KOEI SANGYO CO., LTD.||SATO/Kazuhiko|
|HOSOKAWA MICRON CORPORATION||KISHIGE/Toshihide|
|KANSAI WIRE NETTING CO., LTD.||YOSHIDA/Yuichi|
|SEISHIN ENTERPRISE CO., LTD.||TAKAHASHI/Ryuji|
|TOKYO SCREEN CO., LTD.||OGITA/Yoshihiro|