The Basics of Aggregate and Recycle Crushing


The basics of aggregate and recycle crushing

Crushing is the process of breaking apart large pieces of rock and concrete into a smaller, more manageable size that allows them to be repurposed and reused. It generally involves using a primary, secondary, and sometimes a tertiary crusher or other specialized machine to reduce the size of concrete and aggregate, so they are suitable for use in a wide variety of construction projects, including road building, foundation laying, landscaping, retaining walls, and many others. Most materials will also require a screening process to meet specific sizing requirements.

Whether your business is creating and selling recycled aggregate, or you’re completing concrete and aggregate crushing as part of a wider job, there are some key basics that you should be aware of.

Familiarize yourself with the entire aggregate and recycling crushing process.

There are three overall parts to every aggregate and concrete recycle crushing job. The first is removing and breaking up material on your worksite into more manageable sizes with hydraulic breakers, pulverizers, or other demolition machines. The second part is removing a large part of the metal from the concrete, so that the crushing and screening process can be obtained with minimal damage and equipment wear. The third and final part of the process is using your concrete crusher to reduce the size of your material into even smaller pieces that can then be used in other building projects.

Within that third step can be various concrete and aggregate crushing processes that further break down your material into the required size for specific applications.

Utilize the best aggregate and recycle crusher for each stage of the job.

Using the correct concrete or aggregate crusher for each part of your material processing operation is crucial for your project’s success.

Jaw Crushers

This type of crusher employs compressive force to break down material into smaller pieces. They are available in a variety of sizes, depending on how big your initial chunks are and the volume of work you are handling. This type of crusher functions by using two vertical jaws to create a V shaped opening called a crushing chamber. One jaw moves, and the other one remains in place; the material in the chamber is crushed between the two jaws into smaller pieces that then move farther down the V shape until they fall out of the bottom of the jaw dies or plates. No matter what brand/color of jaw you choose, the main component in sizing a jaw is referred to as the “reduction ratio”. All jaw crushers will fall into the range of a 6-8 to 1 reduction ratio. If you have an 18” piece of material and a 6 to 1 reduction ratio, you can expect a 3” product coming out of the jaw crusher. These ratios can be adjusted and tuned for your specific product requirements by adjusting the “closed side setting” in the action of the jaw. The smaller the closed side setting, the less throughput you’ll achieve. Jaw crushers are typically used in a primary application to reduce the material to a consistent size for further reduction by a secondary crusher. Jaw crushers are available in both mobile, portable, and stationary configurations.

Cone Crushers

This type of crusher also uses compressive force to break down material. However, unlike your jaw crusher, cone models utilize a rotating cone that compresses and breaks down aggregate materials against the walls of the crushing chamber. Cone crushers will require a specific feed size to match the style of liners (coarse, medium, fine) installed into the crusher. Like the jaw, these liner configurations are very specific to feed size, reduction ratio, and closed side settings. Please consult your aggregate equipment supplier for specific product feed size, closed side settings, and throughput volume to match your application. Cone crushers are mostly used as a secondary crusher after a jaw crusher, and they are not usually the crusher of choice in a concrete recycle application.

Impact Crushers

Unlike jaw or cone crushers that use compressive force to process aggregate material, horizontal shaft impact (HSI) crusher models employ impact force to smash the material into smaller pieces. The impactor is a horizontal style drum (rotor) equipped with impact bars (blow bars, breaker bars) that spin at a defined RPM or FPM designation. As the material enters the impact chamber, these bars hammer the material into a hanging curtain at a preset gap setting. Then the material enters a secondary curtain that has a smaller preset gap setting, before falling out of the bottom of the crusher onto a gathering system that leads to a conveyor. Impactors typically have a larger ratio of reduction of 16-20 to 1 unlike the jaw crusher that has 6-8 to 1. Horizontal impactors are usually available in 2, 3 and 4 bar configurations. Consult your manufacturer or dealer to understand which configuration fits your specific application. Also, the impact bars are available in various metallurgies to accommodate impact and wear factors related to different materials. Impactors are generally the most versatile crusher for a wide variety of applications and will yield a more cubical product than compression style crushing. In asphalt recycling, the impactor is the most preferred choice of crushers.

Screening your aggregate and recycled material

After you have completed the aggregate or recycle crushing process, most materials will need to be separated into specific size particles to produce a state regulated product (spec material). By using vibrating screens, you can separate these various pieces based on how large they are, allowing you to utilize the different sizes for particular applications. Multiple styles of screens can be used in the separation process, including horizontal screens, inclined screens, scalping screens, high frequency screens, multi frequency screens, single and multi deck screens, and wet and dry screens. Some screens are incorporated into the mobile/portable plant as a closed circuit operation.

Selecting the right equipment for your crushing and screening project

If you’re just beginning with concrete and aggregate crushing, you may not be 100% sure which types of machines will be best for your requirements. In these situations, we recommend relying on the experts like our team here at Columbus Equipment Company. We will look at your specific operation, define how you are using your crushed aggregates and recycled materials, utilize our large array of factory resources and partner with you to develop the best strategy for your crushing/screening/washing/conveying equipment requirements. Our Aggregate and Recycle Team are specialists who are here to make your purchase or rental an easy and profitable experience.

Locate the best market for your aggregates

Aggregate and recycle crushing and screening can create more revenue streams for your company. Depending on the grade and quality of your recycled material, there are a variety of different markets that might be able to use it:

  • Construction contractors
  • Road building operations
  • Landscapers
  • Homeowners
  • Water management contractors
  • And many others!

Improve your sustainability

Whether you are processing the recycled material to use on your own, or you’re selling the recycled aggregate to other buyers, you will now have a new recycled resource for your business. By repurposing and reusing stone and concrete for your aggregate instead of new material, your waste concrete will no longer be placed in a landfill, and you will no longer need to be dependent on virgin material.

If you have any questions about the aggregate and recycle crushing equipment and applications, or you need to choose the best crusher or screen for your operation, reach out to our team today!