Media milling

Abstract

This invention describes a process for preparing a dispersion of solid particles of a milled substrate in a fluid carrier comprising the steps of (a) providing a plurality of large size milling media to the milling chamber of a media mill and forming a depth filter therefrom on an exit screen or separator in the milling chamber; (b) adding to said milling chamber a plurality of small size milling media optionally containing additional large size milling media, a conglomerate of a solid substance comprising a substrate to be milled and optionally one or more than one surface active substance, and a fluid carrier; (c) milling said conglomerate in said milling chamber to produce very small milled substrate product particles; and (d) separating said milled substrate particles suspended in said fluid carrier from the media through said depth filter; wherein the exit screen comprises openings of size S ; the large size media have a size distribution S of which all are larger than S ; the small size media have a size distribution S which are smaller than S ; the very small milled substrate particles have a size distribution S and are smaller than all of the small media; and the large size media and the small size media are essentially retained in the milling chamber.