TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The secondary pulverizer comprises a machine base provided with a material box and a power system. The upper part of the material box is connected with a material hopper. The lower part of the material box is provided with a material exit. The power system comprises a power shaft and a knife tray component. The power shaft is vertically inserted into the material box. The knife tray component is mounted on the power shaft in the material box. The knife tray component comprises two trays and four knife shafts. The two trays are fixedly connected with the power shaft in turn in a vertical direction. The four knife shafts are connected between the upper and lower tray trays by long bolts. The four knife shafts are arranged uniformly at the peripheries of the knife shafts. The knife shafts are provided uniformly with several blades in vertical direction. The blades at the knife shafts are arranged alternatively in the vertical direction, where all the blades are arranged horizontally. A toothed ring is arranged at the inner wall of the material box corresponding to the knife tray component of the power shafts. The middle part of the outer end of the blade is provided with a convex tooth, where two sides of the outer end of the blade are symmetrically provided with several teeth in a stepwise manner. The toothed ring is of a straight-groove type. The material box is cylindrical, whose upper part is provided with a box cover, where one side of the box cover is provided with a feeding hole. The periphery of the back part of the feeding hole is provided with a guide ring. The power system comprises a motor, a motor belt wheel, a transmission belt and a driven belt wheel. The motor is mounted at the second connection element by a bolt pair. The second connection element is mounted at the machine base. The motor belt wheel is mounted at the outlet end of the motor. The transmission belt is sleeved on the motor belt wheel and the driven belt wheel. The driven belt wheel is mounted at the upper end of the power shaft. The motor belt wheel, the transmission belt and the driven belt wheel are covered with a protective shade. The upper part of the power shaft is mounted in the box cover by the power shaft and a bearing. A bearing block and the bearing are mounted at the rear part of the box cover. ACTIVITY - Fertilizer.