Primary crushers are designed to crush large pieces of rock 1 to 4 feet in diameter into pieces approximately 5 to 6 inches in diameter. These crushers operate at 620 to 800 rpm and are powered by 250 to 500 HP electric motors.

After going through the primary crusher, the rock is transported by conveyer to a "surge" pile. From the surge pile the rock is again conveyed through a tunnel to secondary crushing stations.

Hauling

Stockpiling