The main equipment of producing pellet by rotary kiln are chain grating machine, rotary kiln and circular cooler. And the chain grating machine is the most important equipment. Chain grating machine’s main part is grate bed, which is to dry and preheat pellet by remained heat flow. Grate bed consists of chain link, grate plate, side plate, pipe spacer and protecting sleeve. Grate plate is shaped and casted by .heat-resisting alloy steel, its casting tolerance is CT6. The grate plate castings cycle through the grate furnace on a continuous cycle and carry the magnetite iron ore pellets through the process and into the kiln. The maximum temperature of the grate plate goes to approximately 650℃ when it discharges its load into the kiln and then the castings cool down to approximately 150℃ in free air, as it returns to the tail end.