The industrial used sand and gravel typically are mined from open pits of naturally occurring quartz which is rich with sand and sandstone. Mining methods depend primarily on the degree of cementation of the rock. In some deposits, blasting is required to loosen the material prior to processing.
Gravel Crushing Process
The material may undergo primary crushing at the mine site before being transported to the processing plant. The mined rock is transported to the processing site and stockpiled. The material then is crushed. Depending on the degree of cementation, several stages of crushing may be required to achieve the desired size reduction.
Gyratory crushers, jaw crushers, roll crushers, and impact mills are used for primary and secondary crushing. After crushing, the size of the material is further reduced to 50 micrometers (m) or smaller by grinding, using smooth rolls, media mills, auto-genous mills, hammer mills. The ground material then is classified by wet screening, dry screening, or air classification. At some plants, after initial crushing and screening, a portion of the sand may be diverted to construction sand use.
Crushing Process Machine
The above mentioned gravel crushing equipment cooperates with each other to complete the whole crushing process. Raw materials will be taken into jaw crusher evenly through vibrating feeder. Then belt conveyor will take the crushed materials into cone crusher or impact crusher for further crushing. Vibrating screen is used to separate the unsuitable size materials which will be taken back to crusher to be crushed again through belt conveyor.