| 摘要 |
A method and a device for forming spheres from irregularly shaped, very small particles of glass or other thermoplastic material, and the spheres which are produced thereby, with a thin carbon-containing coating being applied to the particles, after which the particles are caused to pass through successive fluidized beds 15, 110 and 130. The first bed 15 has an inert atmosphere and is maintained, by means of heating elements 67, 69, 70 at an elevated temperature which is sufficiently high to permit surface tension to shape the particles into a spherical form while they are in a fluidized state in the first bed 15. A fluidizing material is introduced into the bed by means of elements 53, 54, 55, 56, 57 for suspending the particles therein and fluidizing it in such a way that the particles move at an essentially constant level the whole time they are in the bed. The spherical particles subsequently pass through successive additional beds 110 and 130, where they are cooled down to an intermediate temperature, which is sufficient to cause the particles to solidify, are exposed to an oxidizing atmosphere, which completely removes the coating, and are then cooled down further while being maintained in a fluidized state. The inert gaseous atmosphere inside the first bed 15 is withdrawn continuously and recirculated through the system. <IMAGE> |
