The name of rob mill is from the medium in mill is steel rob. The rob mill is generally wet overflow type used in the first stage grinding, especially in artificial sand and stone, mineral processing plant and power sector of chemical plant.
The rod mill is driven by motor with speed reducer and peripheral large gear, or low speed synchronous motor with peripheral large gear. The grinding medium --- steel rod is put into the cylinder which is lifted, and then fall under the action of the centrifugal force and friction force. The materials entering into cylinder form the feeding inlet are grinded by movable grinding medium and discharged out by overflow and continuously feeding.
The grinding medium of rod mill is steel rod which is recognized that the length of rod is less than 7m because the large length is easy to twine. The diameter of rod is 75~150mm.
Grinding rod should have enough stiffness and hardness to keep straight, and it should not be too crisp which causes the rod broke into pieces without enough wear. If the rod is too soft, it is easy to bend and twine which makes trouble to clean machine.
（1）Rod mill is usually selected in order to prevent over grinding in gravity or magnetic separation plant of tungsten tin and other rare metals mine.
（2）In two stages grinding, the capacity of rod mill used in the first stage grinding is larger than ball mill's.
（3）In some cases, rod mill can replace short head cone crusher