It takes use the crushing principle of combination of impact crushing, scroll crushing and grinding, which is similar as that of ball mill, however it is different. Its main parts are 2 pcs large-scale horizontal rotary cylindrical shells on scrolling shaft and there are several large-scale steel ball (max. could be Φ120mm) inside of shell, meanwhile double U type scaleboard on the inside wall of shell. When the rough pulverizer turns, the steel balls are brought to some height, when they fall down, they will break up and crush the material meanwhile by the relevant movement of grinder, crushed material will be further grinded and pulverized. Due to increasing of rotating speed and ball diameter, the impact force will be strengthened and crushing capacity are largely improved which update the traditional grinding appearance. Thus this is the obvious point that is different with normal ball mill. It is assorted with circle grinding technical principle, so material will be grinded in the front part of shell,  then material will be screened in the kiln end, and material with little grain after screened will be discharged through discharging device on the circle of shell. However the material with larger grain will be discharged into the circle feed back pipes on the outer of shell through the discharging device installed on the circle of shell, then these material will be sent into front feed back device along with the rotating of shell and enter into front part of mill for re-grinding until the granularity of material is less than the hole diameter of screening, they could be discharged. This could ensure the uniformity of the discharged material grain and largely improve percent of pass on fineness.

    

 Main shaft takes use rolling shaft which could save over 10 percent electric power, and 80% lubrication oil , increase 12-20% load of grinder and over 10% of working speed of ball mill, which could reach best operating efficiency, improve grinding capacity and raise over 30% output. Meanwhile its starting is fast and operation is stable. Thus it had avoided the stop calculation and production for changing scrapping caused by frequent damage of Babbitt Metal Tile. Scaleboard of shell utilizes Double U type Scaleboard which have better lifting capacity and the contact between ball and scaleboard is surface contact, thus the crushing efficiency is higher which eliminate the dead angle of grinding such as step liner (contact between ball and liner is point contact) and so on.  The process flow of circle rough pulverizer of pre-grinding is not only reasonable and economical, but also its operation is simple, maintenance is less and operating rate is higher as ball mill. Seen from above, its efficiency has reached or exceeded the efficiency for utilizing roller mill as pre-grinding equipment. Old type ball mill, short rough mill, ball crusher and various crushers could be put on a par with modernized XLCM circle grinding energy-saving rough pulverizer, as the grinding efficiency and crushing efficiency of this equipment has increased over 30%. Thus we suggest cement enterprises utilize this kind of pre-grinding process flow which has obvious effect on reducing grinding power consumption and increase integrate economic benefits.