This series of products is an update and upgrade of technology of original mill equipment which is developed by authoritative powder engineers in our company on the basis of many years of experience in research and development and customers' practical situation. Instead of traditional closed-circuit system pulverizing equipment, whose temperature will rise in the process of continuous running, so there is a potential safety hazard, and this even leads to some special material properties to change, we design and develop the milling machine of open system which combines high yield, high performance, energy conservation and environmental protection as one. This product is suitable for the grinding all kinds of inflammable and non-explosive materials whose Mohs hardness under seven levels, and humidity below 6%, such as limestone, calcite, marble, barite, gypsum, kaolin, lime,phosphate rock, bentonite, manganese ore, and petroleum coke. Fineness can be adjusted between 0.18-0.15mm (80-600 mesh).