Multi-stage integrated ball mill

According to the multi-stage integrated ball mill, a fixed cylinder, an outer ball milling cylinder, an inner ball milling cylinder and a three-layer ball milling cylinder are arranged, materials with larger particles are subjected to ball milling in a coarse milling area, materials with smaller particles screened out by the coarse milling area are subjected to ball milling in a fine milling area, and the large particles and the small particles are separately milled, so that the ball milling is more targeted, and the ball milling efficiency is high; in addition, the materials which are ball-milled into powder are screened out to a collecting area, and large particles continue to be ball-milled, so that the situation that the powder which is ground to reach the standard continues to be left in the ball-milling barrel for ball-milling is avoided, the burden of the ball-milling barrel is relieved, continuous ball-milling is achieved, feeding and discharging are conducted at the same time, and the ball-milling ef