A process and apparatus for micronizing solid carbonaceous material and preparing carbon oil mixtures. Micronization is accomplished by projecting particles of a carbonaceous material into the point where a number of fluid streams intersect and by then impacting the particles against a rotating cone. The resulting micronized particles are then separated from the fluid in which they are entrained and are mixed with fuel oil. A preferred fluid for use in this process is a gaseous mixture consisting of about fifty percent steam and fifty percent flue gas.