When starting up, inert gas is continuously injected to replace the air in the system until the whole system reaches the safety value set by the oxygen content detector. In the starting feeding device, the raw materials in the silo are evenly added to the main engine, and the compressed inert gas is ejected at high speed through the specially designed and optimized nozzle. The material is accelerated by the supersonic jet of expansion and cooling, and crushed at the intersection of the nozzle (the grinding area in the center of the grinding chamber) due to mutual impact and collision. The crushed material enters the grading area with the updraft, and the fine powder reaching the particle size requirements can pass through the grading wheel and be collected by the cyclone separator and trap. Coarse particles are returned to the grinding area for further grinding, and inert gas is returned to the system for recycling after being treated by a filter.