Crushing Equipment 101

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Mining, aggregate and mineral processing, recycling, and other material handling plants usually need to reduce the size of their raw materials to create something sellable. Once their raw material is mined, harvested, or collected, it needs to be broken down into something closer to the end-product.

This is where crushing equipment comes in. Crushers are an important part of a full circuit material handling plant. They’re usually the first or second step, after the raw material arrives.

For the first installation of our Equipment 101 series, we’ll take a look at everything you need to know about crushing equipment. Kemper’s experienced team knows what it takes to turn raw material to a profitable product. Read on to learn more about how crushing equipment fits into material handling, and how Kemper can help:

What is Crushing Equipment?

In the simplest terms, crushing equipment is used to reduce the size of material into much smaller pieces. These are heavy pieces of machinery, usually part of a material handling system or plant. A rock crusher uses significant force to impact materials to the point of breaking or separating.

Most crushing equipment is designed with heavy plates or jaws used to apply pressure to whatever material have been fed into the chamber. Crushers can be smaller and portable, but are usually built into a full circuit material handling system. You’ll find equipment like conveyors, crushers, and screening machines at most rock quarry or mineral processing operations. These systems tend to work together to break raw material into marketable products.

How Does Crushing Equipment Work?

Chambers with heavy, durable plates or jaws are the main components of most crushing equipment. After raw material is fed into the crusher, the plates come together to reduce the size. These heavy-duty plates move both up and down, creating enough force and pressure to reduce the size of the material significantly.

Some plants use multiple crushers to reduce the size of their raw materials. Not all crushers can handle large pieces, so a heavy-duty crusher is the first part of the material handling circuit. Jaw crushers can handle really large pieces. They’re used to break those large pieces into something more manageable for the smaller crushers.

If a jaw crusher is necessary, the reduced material is then fed into a finer crusher by a conveyor belt. After the secondary crusher reduces the material even more, it’s moved to a screening machine by another belt. The material needs to be broken into manageable pieces before it reaches the screening equipment, making crushers a vital component of production.

How is Crushing Equipment Used?

Crushing equipment is one of the very first steps for a variety of material handling plants, productions, and jobs. Each job starts with a different material, calling for a different type of crusher. Most crushers function in a similar fashion, but the end products are used for many different applications. Here are just a few industries that use crushers:

• Mining
• Rock Quarries
• Mineral Processing
• Recycling

The mining and quarrying industry is one of the largest users of crushing equipment. Raw material is blasted or harvest from deep underground. For these materials to be profitable, they have to go through an extensive material handling system. The material is moved from the mine, fed into a crusher, than screened to separate the particles. Crushing equipment works hand-in-hand with all of the other machines to produce an end-product – like gravel for roads, salt for winterizing, and more.

The recycling industry also uses crushers to break down glass bottles and containers. After the glass is loaded into a special crusher, it’s crushed into raw material. It’s then melted down and repurposed into recycled glass containers, just for the process to being all over again!

What Does Kemper Do?

Kemper’s team has over 30 years of experience in the material handling industry. Each crusher plays a different role in a job. It’s important to make sure the best crusher is used to create the desired end product. Kemper supplies and installs various types of crushers, including:

Our team doesn’t stop and recommending and installing the crusher you choose. We go further by consulting, planning, and designing full circuit systems. Kemper is a full-service material handling supplier capable of designing, building, and even repairing your entire system.

Different types of crushers are optimal for distinct crushing needs

All rock crushers can be classified as falling into two main groups. Compressive crushers that press the material until it breaks, and impact crushers using the principle of quick impacts to crush the material. Jaw crushers, gyratory crushers, and cone operate according to the compression principle. Impact crushers, in turn, utilize the impact principle.

Jaw crushers

Jaw crushers are mainly used as primary crushers. Their main purpose is to reduce the material to a small enough size that it can be transported by conveyors to the next crushing stages.

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As the name suggest, jaw crushers reduce rock and other materials between a fixed and a moving jaw. The moving jaw is mounted on a pitman that has a reciprocating motion, and the fixed jaw stays put. When the material runs between the two jaws, the jaws compress larger boulders into smaller pieces.  

There are two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action.

A double toggle crusher has two shafts and two toggle plates. The first shaft is a pivoting shaft on the top of the crusher, while the other is an eccentric shaft that drives both toggle plates.

The chewing movement, which causes compression at both material intake and discharge, gives the single toggle jaw better capacity, compared to a double toggle jaw of similar size. Metso’s jaw crushers are all single toggle.

Gyratory crushers

Gyratory crushers are frequently used in the primary crushing stage and a little less often in in the secondary stage.

Gyratory crushers have an oscillating shaft. The material is reduced in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly.

The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners.

The gyratory crushers are equipped with a hydraulic setting adjustment system, which makes it possible to regulate the gradation of the crushed material.

Cone crushers

Cone crushers resemble gyratory crushers from technological standpoint, but unlike gyratory crushers, cone crushers are popular in secondary, tertiary, and quaternary crushing stages. Sometimes, however, the grain size of the processed material is small enough by nature and the traditional primary crushing stage is not needed. In these cases, also cone crushers can carry out the first stage of the crushing process.     

Cone crushers have an oscillating shaft, and the material is crushed in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly.

An eccentric shaft rotated by a gear and pinion produces the oscillating movement of the main shaft. The eccentricity causes the cone head to oscillate between open side setting and closed side setting discharge opening.

The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is called interparticular crushing also.

The cone crushers are equipped with a hydraulic setting adjustment system, which adjusts closed side setting and thus affects product gradation.

Depending on cone crusher, setting can be adjusted in two ways. The first way is for setting adjustment to be done by rotating the bowl against the threads so that the vertical position of the outer wear part (concave) is changed. One advantage of this adjustment type is that liners wear more evenly.

Another principle is that of setting adjustment by lifting or lowering the main shaft. An advantage of this is that adjustment can be done continuously under load.

To optimize operating costs and improve the product shape it is recommended that cone crushers are always be choke fed, meaning that the cavity should be as full of rock material as possible. This can be easily achieved by using a stockpile or a silo to regulate the inevitable fluctuation of feed material flow. Level monitoring devices detect the maximum and minimum levels of the material, starting and stopping the feed of material to the crusher, as needed.

Impact crushers

Impact crushers are versatile crushing machines that can be used in any stage of the crushing process. However, the features and capabilities of different impact crusher types vary considerably.

Impact crushers are traditionally classified to two main types: horizontal shaft impact (HSI) crushers and vertical shaft impact (VSI) crushers. These different types of impact crushers share the crushing principle, impact, to reduce the material to smaller sizes, but features, capacities and optimal applications are far from each other.

Horizontal shaft impact (HSI) crushers are used in primary, secondary or tertiary crushing stage. HSI crushers reduce the feed material by highly intensive impacts originating in the quick rotational movement of hammers or bars fixed to the rotor. The particles produced are then further fragmentated inside the crusher as they collide against crusher chamber and each other, producing a finer, better-shaped product.

Vertical shaft impact (VSI) crushers, on the other hand, are used in the last stage of the crushing process, especially when its required that the end product has a precise cubical shape. 

VSI crusher can be considered a ‘stone pump’ that operates like a centrifugal pump. The material is fed through the center of the rotor, where it is accelerated to high speed before being discharged through openings in the rotor periphery. The material is crushed as it hits of the outer body at high speed and due to rocks colliding against each other.

Are you interested in learning more about machine that crushes things? Contact us today to secure an expert consultation!