Rapid Size Classification of Ultrafine Particles Using Surface Characteristics [Translated]†

Abstract

Size classification of ultrafine particles is one of the most difficult techniques in materials processing. We developed a novel ultrafine particle classification method based on heterocoagulation phenomena of colloidal particle. In this paper, rapid size classification of silica particles (median diameters of 100nm and 300nm) from their mixed suspension was examined in various solution chemistries by column bed packed with ferro-nickel slag (FS) as a fibrous collector medium. Many of 100nm-silica particles selectively attached to the FS surface during passing through the FS-packed column, while 300nm-silica remained in an outlet suspension. Newton’s efficiency depended on pH and ionic strength; optimal classification was attained at pH3.5 in 10mM KNO3. These results were qualitatively explained by DLVO-type interaction energy curve, indicating that interfacial interaction of both particle and collector determined the classification efficiency. Furthermore, particle concentration and superficial velocity had an influence on classification efficiency. This method proved to be simple, rapid and cost-effective for classifying ultrafine particles in aqueous media.† This report was originally printed in J. Soc. Powder Technology, Japan, 39, 175-182 (2002) in Japanese, before being translated into English by KONA Editorial Committee with the permission of the editorial committee of the Soc. Powder Technology, Japan.

Keywords

• size classification
• zeta potential
• silica particle
• fibrous slag
• dlvo theory