In this article we are going to focus on types of crushers rather than manufacturer’s names; these being Jaw Crushers, Impact Crushers, Cone Crushers, and Shredders. To determine which of these crushing technologies is best for your application, we must first know the material that needs crushed and to what particle size.
Hard Rock: Many rock quarries crush hard rock. In these applications we highly recommend a jaw crusher as the primary crusher, which reduces the rock down to 3-4”, and then a cone crusher as the secondary crusher to further reduce down to the desired size. Often times the secondary crusher is not used and the primary crusher conveys into a screening plant which separates the material into 3 products.
Not all jaw crushers are designed to handle hard rock though. In fact, most of the smaller jaw crushers on the market are only designed to crush concrete, block, and brick and not hard rock.
In many cases you may hear of a customer adding shims to a jaw crusher, allowing the jaws to become closer (for example 2”), to make a finer product. This can be easily done; however, you run the risk of damaging your crusher. A secondary result is that production will be cut in half and your jaw plates will experience quicker wear.
Concrete / Concrete Block / Brick: For this material we normally recommend a jaw crusher, impact crusher or a recycling shredder; however, other variables come into play to determine which is best. Is dust an issue? Am I wanting a finer or coarser material? Is there a great deal of rebar in the material?
My favorite (newer) technology is the shredder for concrete, block, and brick. This shredder can also crush asphalt in 100 degree weather which is a huge perk. It also allows for less prep work (by accepting larger material) and is superior when dealing with contaminants like rebar. Out of all of the options on the market, the shredder produces the least amount of dust and is the easiest to run.
My second favorite technology for this application is the jaw crusher. It experiences slightly less wear than a shredder but considerably less than an impact crusher. The jaw produces a little more dust than the shredder but much less than an impact crusher. Jaw crushers are not recommended for asphalt unless it is below freezing temperatures.
My least favorite type of crusher is the impact crusher. It is true that impact crushers have higher production and the most reduction compared to the two previously mentioned technologies; however, it is at a cost. Impact crushers create a great deal of dust and wear parts must be replaced on a regular basis. In short, you must have access to a mechanic given that blow bars need to be replaced frequently. It’s worth noting that this article is written from the perspective of the smaller operator who does not have full time mechanics. If I had full time mechanics and my material was basically clean then I would suggest the impact crusher despite its faults since it will yield the most production, the most reduction, and can also handle asphalt in high temperatures.
ASPHALT: The most popular type for crushing asphalt is the impact crusher. The wear on the machine is significant, but it yields the most production. I personally like the Shredder for this application as the cost per ton is considerably less and, compared to an impact crusher of similar cost, and the shredder will accept larger pieces meaning less prep time. There are many shredder manufacturers on the market, but only one that we recommend for recycling concrete, block, brick, and asphalt; the CAMS Shredder, as it is specifically designed for such material. The CAMS Shredder can also shred extremely dirty or even muddy concrete with no issues. If you have any questions or interest in a machine, feel free to call us at GrinderCrusherScreen to answer your crushing equipment questions.