How Does a Rock Crusher Work?

How Does a Rock Crusher Work?
A rock crusher, as the name implies, is a device that crushes large rocks into smaller, more manageable pieces. Utilized primarily in the construction and road-building industries, crushers can process natural rock and reclaimed materials like concrete to produce aggregate products such as gravel, rock dust, or rock fill used for erosion control or landscaping.
The basic design of most crushers includes a hopper at the top where raw material is held before being fed into the crushing mechanism by either gravity or a belt drive. After the material is crushed, it is then discharged through an opening at the bottom where it can be further processed. The several types of crushers include jaw crushers, impact crushers, cone crushers, gyratory crushers, and roller crushers.

Jaw Crushers

Jaw crushers, sometimes referred to as toggle crushers, consist of two vertical plates, one moveable, one stationary, that grind rocks between them through compression. The jaw plates start out farther apart at the top but move closer toward the bottom, forming a tapered chute that looks like a collapsible V. The plates work together through gradual inertia that is produced by a weighted flywheel. As the rocks move down the chute, the tapering allows them to become progressively smaller before they exit through an output opening at the bottom. Jaw crushers can handle materials of varying hardness and abrasiveness.

Impact Crushers

Impact crushers use impact motions rather than pressure to crush material and are generally used to process softer, non-abrasive material. There are two types of impact crushers: horizontal shaft and vertical shaft. A horizontal shaft impact crusher breaks rocks with two large swinging hammers fixed on a spinning rotor and is best used on materials such as limestone, basalt, gypsum or granite. A vertical shaft impact crusher uses high velocity to crush material, “throwing” rocks against an anvil until they break apart. The final product of a vertical crusher is usually cubic shaped which is optimal for highway construction and water conservancy projects. It can be used on various materials including quartz, granite, limestone and bauxite.

Cone Crushers

Cone crushers operate by squeezing rocks between a mantle that covers a gyrating spindle and an enclosed concave hopper. Rocks enter through the top and become wedged between the mantle and the concave. Larger pieces are broken up and then fall downward to a lower level where they are broken up further until they are small enough to fall through the narrow output at the bottom. Cone crushers have higher production efficiencies because they are prone to less wear and tear and are easy to operate. They are ideal on hard and medium-hard stones used in stone mining or building material.

Gyratory Crushers

Gyratory crushers have fixed concave surfaces and conical heads that that move in a slightly circular pattern. Rocks are crushed when the gap between these surfaces close together. As with cone crushers and jaw crushers, the rocks get increasingly smaller at each level they fall. Primarily used in mine or ore processing plants, gyratory crushers work with various types of ores including iron and copper.

Roller Crushers

Roller crushers are used on soft, fragile materials such as limestone, chalk and clay. The crushers consist of two rollers, one fixed and provided with a flywheel while the other is adjustable to accommodate the varying sizes of materials. The raw materials are fed through an opening and fall between the rollers, where they are crushed to one-third to one-fifth of their regular size. After reduction, the final products exit through an output opening. If an extremely hard object gets jammed between the rollers, the crusher feed will automatically stop to prevent damage.

Although rock crushers generally are large and heavy, a new generation of rock crushers now offers portability and on-site crushing, greatly improving production by eliminating transportation time to fixed plants. Some of these newer models combine the actions of jaw and roller crushers and have a wide range of compression strengths. As technology advances, industry heads can expect even more efficiency, which will ultimately translate into greater cost savings.