diagram of crushing machine in geology

There are some cases where the process requires a fine dry product and a quaternary stage of crushing will also be included. The purpose of the primary crusher is to reduce the ROM ore to a size amenable for feeding the secondary crusher or the SAG mill grinding circuit. The ratio of reduction through a primary crusher can be up to about 8:1.

The rock is fed into the top of the crusher and falls down into the crushing chamber, during the process the rock is crushed between the lining of the crushing chamber and the main shaft until it is small enough to fit through the gap at the bottom of the crusher.

Charge is fed by trucks, tip-wagons, side dump cars, and conveyor belts. Gyratory crushers are operated in open circuit. The feed is limited to 1 to 1.5 meters in size. Therefore, if a 3 mm crusher product is required, maximum feed size to the secondary crusher would be 240 mm. Thus, the feed to the primary crusher should not exceed 2400 mm.

Crushers have more efficient transfer of applied power to the breakage of rock than grinding mills. Typically a crushing flowsheet for a mineral processing plant will have from one-to-three stages of crushing. There are some cases where the process requires a fine dry product and a quaternary stage of crushing will also be included.

The product size is controlled by the crusher''s setting. If a more accurate control of the size is required, the crusher is combined with a screen into a closed circuit. Is a common way of combining a crusher and a screen in such a way that the oversize material goes back to the crusher.

Both gyratory crushers and cone crushers work in a similar way, the main difference being that the cone making up the main shaft of the cone crusher is less steep than that inside the gyratory crusher. Typically a gyratory crusher will be used for primary crushing whereas a cone crusher will be used for secondary crushing.