Effects of Dry Grinding on Kaolin Minerals. III. Halloysite

Publisher Website
Google Scholar
Abstract
The effects of several-hundred-hour mechanical-mortar dry grinding of halloysite were studied by X-ray diffraction, differential thermal, electron microscopic and other methods and they were compared with those of kaolinite and Kibushiclay. It has been found that there are two sorts of structural change caused by dry gringing in halloysite as in the case of kaolinite. One is the production of a non-crystalline material attended with disordering of crystallites, and the other is the process of reaggregation. In a certain stage of grinding, the reaggregates come to have a zeolitic structure. This stage of grinding corresponds to the maximum point on the base exchange capacity curve and the inflection point on the density curve. The particle which has a zeolitic structure is uniformly spherical. As the grinding progresses further, halloysite changes into an amorphous substance, and the particle size increases irregularly. In consequence, it was found that the effects of dry grinding on kaolin minerals depend strikingly on the structural perfectness of unit layers of the original kaolin minerals, that is, the internal degree of crystallinity.

This publication has 7 references indexed in Scilit: