This invention provides a process for producing fine rubber powders by using waste rubber, comprising the steps of pre-pulverizing waste rubber into particles with a size of 1-4 mm; soaking the particles in a solvent selected from one or more alcohols andor ethers; and pulverizing the soaked rubber particles into rubber powders with a size of less than 180 m. The heating body includes a tube, a heating member disposed in the tube, and a supporting unit disposed along a length of the tube to maintain a predetermined space between the tube and the heating member. In the event the message is classifiable by the machine classifier, the statistical message classifier is updated according to the reliable classification made by the machine classifier.