Verfahren zur Vergroesserung der Oberflaeche von Festkoerpern

In a process for increasing the surface area of particles which absorb liquids at least to a limited degree, the particles are exposed to a liquid, or to a humid atmosphere containing the liquid, until the liquid has penetrated into at least the surface layers. The liquid-bearing particles are then exposed to microwave radiation until the penetrated liquid is vaporised. Also claimed are processes using the principle of the above process for roughening the surface of or for the size reduction of particles. ADVANTAGES - The process is simpler and uses less energy than mechanical or chemical processes, and can be applied to very small or less friable materials.