Crushing Rock

Crushing Rock – Jaws, Cones, and Impactors

Crushing rock is the focal point of any mining, excavation or construction dig project. Regardless of what you are mining for, from base metals, gravel and coal to iron, copper and other minerals you will need to crush large rock down for further processing. There are several types of crushers that will quickly and efficiently break down large rock including many sizes and models of jaw crushers, cone crushers, roll crushers, and impact crushers. As with other crushing equipment there are several benefits to buying used crushing equipment instead of brand new. There are also many types of raw materials with varying degrees of density, abrasiveness, compressive strengths, and feed sizes.

One of the more versatile of the rock crushers is a jaw crusher, and will typically be used as a primary crusher. Jaw crushers can be used for quarried materials, sand and gravel and recycling projects. Also known as a compression crusher, jaw crushers use two “jaws”, one fixed and the other moving in an eccentric motion, to move rock down a tapered throat over wearable dies, so material is crushed progressively into smaller pieces. A flywheel moves the shaft to create a motion that closes the gap at the bottom where the rock is crushed and reduced material is discharged to a conveyor for further processing. Jaw crushers can be mounted onto structures, portable wheel mounted chassis, and heavy duty tracks. Jaw crushers can be powered by diesel engines, electric motors, line service, and by hand.

Cone crushers are similar in design (compression crusher) to jaw crushers, consisting of a concave surface and a conical head, with raw materials traveling downward between two wear surfaces that progressively crush the material. The inner core of a cone crusher has a slight circular movement on the central vertical spindle that gyrates when the material is fed to the bowl. This action causes the crushing by the closing of the gap between the mantle and the fixed concave liners. Cone crushers can be used for primary or secondary crushing but are most commonly used in secondary applications in conjunction with a primary jaw crusher.

Impact crushers have the best reduction ratio regarding, feed size to finished product on one pass. Unlike jaw and cone crushers that use compression to perform the crushing, an impact crusher uses the force of impact to “hammer” softer/non-abrasive raw materials such as recycled concrete, gravel, cobble, shale, caliche, glass, limestone, and other materials. They are suited to accept broken concrete with rebar, and other materials with steel or metal. Heavy duty belt and pulley magnets are commonly used with impact crushers. Impact crushers are found in two types, horizontal shaft impact (HSI) and vertical shaft impactor (VSI). Most horizontal shaft impact crushers feature a solid rotor with hammers or “blow-bars” that rotate at a high revolution and break the raw material against inner lined wear plates and the use of a secondary lined apron that is used to adjust the finished product setting of the crushed material that is discharged onto a conveyor belt and typically sent to a screening/separating plant that will divide the required finished products and return any oversized material back to the crusher. Impact crushers can be mounted onto structures, portable wheel mounted chassis, and heavy duty tracks. Impact crushers can be powered by diesel engines, generators, electric motors, and line service where available.