Rock Crushing and Rock Crushers

Rock crushing

Explosives or excavating are used to remove rock from the earth for crushing. Rock can also be natural, gravel or construction waste. Rock is crushed in two or three different phases: primary, secondary and tertiary crushing. The crushing process often involves one or more phases of screening to separate the different sized varieties.

Rock crushing process

Mobile track-mounted crushers or stationary crushers are used in the crushing process. An excavator or wheeled loader loads the rock to be crushed into the crusher’s feed hopper. The feeder moves the rock material to the crusher.

The crusher breaks the rock into smaller grain size. The biggest crushers can crack boulders that are about one cubic meter in size. The crusher is powered by a diesel engine. From the crusher, the rock material is dropped onto the main conveyor that moves the end product upwards and then drops it into one big pile or into the feed hopper of the next crusher. Metal in the rock material moving along the main conveyor can be separated with a magnet separator, which throws the metal pieces to the side of the conveyor.

The finer portion of the rock material can be screened out already before it advances to the crusher. The screened material can be directed to the main conveyor and will thus end up in the same pile as the end product, or a secondary conveyor can direct it to a separate pile. With some crushers, equipment attached under the main conveyor can screen and sort the end product into two or three separate piles based on the fraction size. The end product piles are removed as needed with a wheeled loader and the material can be loaded onto trucks, for instance.

Different types of Rock crushers

The footprint of small, stationary rock-crushing plants is about one hectare, medium-sized 2– 3 hectares, and large plants up to 5 hectares. Stationary crushing plants consist of various crushers, feeders, screens and conveyors.

Mobile track-mounted crushers

Mobile track-mounted crushers can be moved at a speed of about one kilometer per hour. The parts of mobile crushers used in quarries and contracting include e.g. the crusher, a diesel engine, a generator, a conveyor, a screen and dust- and noise-control systems.

jaw crusher

There are several different kinds of crushers. A jaw crusher is used at the beginning of the process, i.e. in the primary crushing phase to crush the largest boulders. jaw crushers can crush all types of rock, including the hardest granite, brick, concrete and asphalt.
In a jaw crusher, a moving jaw attached to an eccentric shaft compresses the rock against a stationary jaw and the pressure crushes the rock. The grain size achieved with a jaw crusher depends on the distance, or setting, of the lower part of the jaws.

Gyratory and cone crushers

Gyratory and cone crushers are generally used after the jaw crusher for secondary and tertiary crushing. As such, the goal is to produce ballast or fine sand. Gyratory and cone crushers crush all types of rock but not always recycling materials.
Big primary gyratory crushers are used in mines during primary crushing and in other mining and quarrying applications requiring large capacities.

Impact crusher

Impact crushers are used to crush medium-hard rock and softer rock materials like limestone. Impact crushers can be used also to process all recycling materials.

Rock crusher output

Small crushers produce 100-300 tons of aggregate per hour, medium crushers 300-600 tons and large crushers 600-1,000 tons per hour. The biggest rock crushing plants can produce more than 2,000 tons of aggregates per hour. It takes 25,000-50,000 tons of aggregate to build an asphalt road that is one kilometer long and ten meters wide.