Process and apparatus for the manufacture of carbon microballoons

This invention provides a stepped heating cycle for the pre-treatment of phenolic microballoons prior to carbonization thereof, wherein the heating cycle comprises the steps of sequentially: gradually elevating the temperature of the microballoons to a temperature in the range 100° C.-170° C., holding the microballoons at the elevated temperature for 1-24 hours; and gradually cooling the microballoons. This invention also provides a heat-dissipation reactor ( 11, 21, 31 ) which comprises a walled reaction chamber having a bottom and no top, the reaction chamber being fitted with high thermal conductivity inserts. When used in accordance with this invention ( 61 ), the volume within the walls of the reaction chamber is charged with phenolic resin microballoons. In a preferred embodiment, the reaction chamber ( 11, 21 ) is subdivided into a plurality of subchambers by a vertical grid of aluminum plates ( 19, 29 ). In this embodiment, about half or more of the wall area of each subchamber comprises aluminum and a top edge ( 17 ) of the aluminum wall material communicates with atmosphere above the reaction chamber.