cement wall with crushing machine

Rock Crushers: Everything You Need to Know

If you have a need to process sand, gravel, or rock and you do not own the proper rock-crushing equipment, you need to work with a professional company that sells the best new machines for your needs.

If you need rock crushing equipment and feel that buying new machines is the best option, make sure you understand the different types of machines available. While a professional machinery company will be able to work with you to help determine your exact needs, it’s always a good idea to be prepared beforehand. You should first determine the material you need to crush as geology is very important when it comes to choosing the right equipment.

Types of Rock 

The abrasiveness of the rock you need to crush as well as how difficult it is to crush is determined by its type. Sandstone, limestone, and granite are typically the three most common types of aggregates used in the building industry. Crushing these rocks results in materials that can be used in cement or roofing materials, to pave driveways or patios, or to use with a binding material for railroad projects or general construction.

The more you know about the type of rock you wish to crush and its end use, the easier it will be to choose the best equipment to achieve your project goals. 

Here is what you should know about the different types of rock-crushing equipment and the jobs they are best suited for.

Impact Crushers

Impact-style crushers include vertical (VSI) and horizontal shaft impactors (HSI) and are best used with materials such as limestone that are softer and less abrasive. These types of machines break apart materials by throwing it into an anvil or by striking it with a blow bar. Some companies also use impact-style crushers after they have already used a different type of crusher that produces a more elongated stone. This helps further shape the crushed material into a finer consistency with a more cubical nature that can be used for specific projects.

Impact crushers tend to be less expensive than compression crushers and have a higher reduction ratio. They can also break sedimentary deposit-type rocks, like limestone, along natural lines, which rounds off sharp angles and weak edges. This produces an end result that is more sand-like in nature.

However, they can produce an excess of fine materials if used with softer rocks. Impact crushers can also require frequent part changes and can produce a large amount of dust that can be an issue on some worksites.

Compression-Style Crushers

Compression-style crushers are typically used with more abrasive and harder materials such as granite and come in either cone crusher or jaw crusher varieties. These types of machines reduce materials by squeezing them until they break. Many times, impact crushers simply do not have enough power to crush these types of materials. If the initial compression crushing does not reduce the materials to the consistency necessary for the client’s needs, an impact crusher may be used as a secondary crushing method.

Jaw crushers tend to do well with many different types of materials and don’t display as much wear and tear as impact crushers. They also produce minimal fine materials and dust, though the finished product with this type of crusher tends to be larger than 1” and often needs secondary crushing. Jaw crushers are often called ‘rock breakers’ and are used to break up larger, harder materials into more manageable pieces. They then often go to cone crushers, which can reduce the materials to ½” sizes. Cone crushers come in two different types: bushing or bearing. Bearing cones are more efficient and bushing cones cost less to build or repair. In most cases, either will perform the work equally well and the best choice usually comes down to personal preference.

Compression crushers are easier to operate and require less training than impact-style crushers, so many producers first look to them when it comes to their project. You should consult an industry professional for advice on whether a compression-style crusher will produce the type of finished product you need for your project.

Crushing Stations

It is common to use multiple types of crushers for a project and to set them up as a station to perform the necessary work. In many cases, primary, secondary, and tertiary stations are established to reduce the rock to the necessary size, shape, and sometimes consistency.

Primary station – The primary station is usually a horizontal impact crusher or jaw crusher depending on the capacity and the abrasiveness of the material. The goal of the primary station is to reduce the size of the material so it can then be handled by the secondary station.

Secondary station – In the secondary station, size and shape of the rock is the most important goal. A cone crusher is usually used in this station because it allows for changes in the feed and discharge openings and can therefore produce a greater variety of size and shapes.

Tertiary station – The goal of the tertiary stage of the process is to perform the final sizing and shaping of the rock gravel. A cone crusher, vertical shaft impactor, or high-pressure grinding rolls are often used in this station. 

Mobile vs Stationary Crushing Plants

Depending on the length of your project and how mobile your crushing equipment needs to be, you can choose either stationary or mobile crushing plants. Stationary plants are often preferred because they feature a higher capacity and efficiency and a lower production cost with easy maintenance. They also have a lower energy cost if you have electricity on-site and no additional equipment is needed to move them from place to place.

However, if you need to move your rock-crushing plant more than once a year to multiple job sites, you may be better off investing in mobile equipment. These are better suited to smaller projects and can be moved from project to project as necessary. They are not as efficient and have less capacity than stationary plants, but they can be more cost-effective in the long run if you have multiple projects in different areas.

Choosing the Best Machinery Company for Your Needs

Once you have decided you have a need for crushing equipment and you have a good idea of what type of crusher you will need, the next step is to choose the right machinery company with which to work. Make sure you choose a company that specializes in rock-crushing and similar machines. A more full-spectrum, generalized equipment sales company may not have the knowledgeable professionals on staff who can help you with your project. They may not be able to answer all your questions or may suggest the wrong type of machine for your needs.

You should also consider how long the company has been in business and if they are locally owned. If you know of anyone who has recently purchased machinery from the company, it makes sense to ask them about their experience. Your last consideration should be based on personal experience. Either call the company or stop by to ask some questions about your project. Does the person you talk to know what they’re talking about? Do they answer all of your questions thoroughly? Did they take the time to really listen to your project needs and make recommendations accordingly? If you do not feel their customer service is up to par, you may be better off choosing a different company.

If you need help or advice in choosing the right rock-crushing equipment for your operation, contact Kemper Equipment today. We have been in the material handling business for over 35 years and the team at Kemper Equipment are crusher specialists providing complete crushing circuits or retrofits into your existing operation. Kemper Equipment will work closely with you to recommend the best possible solution to your unique needs.