ELECTROSTATIC CHARGES ON CLAYS.

Cation charges present on the surfaces of clay minerals are expected to play a major role in industrial processes involving dry electrostatic separation of granular mixtures containing clay particles. A recent promising potential application has been the removal of clay from British Columbia pulverized coals prior to burning. The clay minerals kaolinite and montmorillonite form the main component of the ash in most Canadian coals: kaolinite in eastern coals and montmorillonite in western coals. The electric charges present on the surfaces of the clay mineral kaolinite have been analyzed from an application point of view, namely, for their ability to transfer onto and remain on other surfaces after contact and separation. Kaolinite samples homoionized with calcium and sodium were prepared from natural kaolin, and the charge transfer after contact and separation with coal was compared for various dry densities of the kaolinite.