Hello, secondary crushing is used in stone production line and sand production line. For example, in the stone production line, the hardness of crushed materials such as granite and basalt is less than 320Mpa, and the secondary crushing process is applicable. Its main equipment is: vibrating feeder-jaw crusher (primary crushing)-stone crusher (secondary crushing, which can be impact crusher, hammer crusher and impact crusher. The general materials of sandstone production line are quartzite and limestone, and the production technology of sandstone production line is basically the same. The main equipment is: vibrating feeder-jaw crusher (generally two, PE jaw coarse crushing, and then PEX jaw fine crushing, if the stone hardness is low, coarse crushing can be omitted)-sand making machine (generally impact type, roller crusher can also be used instead)-vibrating screen-sand washing machine.