The grinding machine is combined with the classification equipment to fulfill the grinding section in the ore dressing process. The ball mill grinds the ore, and the classification equipments such as spiral classifier and hydrocyclone control the grinding grain size. The ball mill and the classification equipment are often combined to form a closed cycle. Ore properties and feed particle size have a great influence on the ball mill's capacity, according to the requirements of the process, the selection of appropriate type of ball mill and corresponding classification equipment is the key link of the production line running smoothly.