Connect the pumping hose of the buffer hopper with the fluid bed dryer&granualator, open the vacuum feeding of the equipment, and realize the transfer of the particles of the fluid bed dryer&granualator to the vacuum buffer hopper. Operate the equipment to lift the frame to a certain height, push the mixing bin under the granulator, the equipment drops, the discharge port of the cone mill and the feed cover of the mixing bin are closed, open the discharge butterfly valve of the vacuum buffer hopper about 30 degrees, start the mill, and the materials fall into the mixing bin after dry milling. After the whole mill is completed, the frame is returned to the initial position in the opposite operation sequence, the vacuum buffer hopper is installed with the online cleaning cover, the discharge port of the mill is installed with the drainage port, the cleaning hose is connected, then the whole operation is completed after online washing.