An Impact Crusher could be described as a ‘rock smasher’ via a fast-moving rotor with a large mass hitting the rock, causing it to fracture. In this article, we’ll delve a little deeper into the principles of impact crushers and how they work to produce in-spec aggregate products.
What a Keestrack Impact Crushing Compartment Looks Like
An Impact Crusher has more adjustability and variability to its operation than a Jaw or Cone crusher; this is due to its ability to fulfil both of these crushers roles in one machine, that is primary and secondary crushing.
An Impact Crusher can reduce an input material to a higher ratio than a standalone Jaw or Cone Crusher; it does this via the use of two aprons suspended over the rotor. Each apron is responsible for 1/2 of the crushing reduction with the 1st apron responsible for the primary crushing operation and 2nd apron fulfilling the secondary crushing; each usually set at 1/3 jumps.
A suitably set up Impact Crusher will have feed pushed through the crushing compartment at 65% capacity (generally speaking, more fines will mean a lower capacity to reduce clogging). The reduction ratio of an Impact Crusher is stipulated in the operating manual; in this example, we will use a Keestrack R3 which is capable of a 1:10 reduction ratio by itself or 1:20 with an after screen and oversize recirculation conveyor.
This would is an ideal crushing scenario, as feed material can be highly variable and of different hardness’s.
Below are some factors and how Impact Crushers can be set up to compensate:
- High Fines Content.
All of Equip2’s Impact Crushers are equipped with pre-screens to remove fines that are unwanted in the produced product. Fines increase wear as they have a friction quality to them and removing them means less wear and more throughput.
- No Large Rock to Crush.
When there is no feed over 100mm like out of some regional rivers, Impact Crushers are preferred to be set up with four blow bars for more hits per pass; fines tend to bounce rather than fracture so more passes mean more hits. Additionally, Ceramic (or harder) blow bars have a higher tolerance for friction over heavier impacts, reducing wear from processing fines.
- Very Soft Material.
Soft material has the downside of being too easy to crush and is pulverised into fines on impact. Impact Crushers, in this situation, may produce an end product with too many fines regardless of the apron GAP setting. In this instance, using two blow bars at a low power setting and a reduced rotor velocity will reduce over energised impacts. Since the initial impact is more than enough to break the feed material down the primary apron can be opened up further to allow for higher input to the secondary apron to adequately size the material. Materials like Asphalt and Lime have these characteristics, and the impact from blow bars themselves is enough to break the product up.
How Keestrack Impact Crushers Save Money in Primary Crushing Applications
Impact Crushers when initially introduced to the market were almost exclusively used as secondary crushers to reduce consistent feed size to a well-graded cubical end product.
Since being brought to the market several decades ago, they have gone through numerous innovations and improvements, cementing them as excellent primary crushers for the last decade that can produce the same reduction ratio that two machines were initially needed to complete.
That’s not to stay Jaw, and Cone Crushers have been wholly replaced or superseded, these also have their place in quarry and crushing operations with features and benefits over Impact Crushers.
How the Keestrack Range of Impact Crushers produces a more profitable product:
- Less speed = Less wear.
The high-speed characteristics of Impact Crushers can result in higher wear. Keestrack’s entire range of Impact Crushers are built around reducing wear, by decreasing the speed necessary to impart energy to the feed material; this reduces wear on the blow bars and aprons with a more meaningful crushing action occurring from the first pass. Keestrack accomplishes this with heavier rotors that have higher inertia to them, resulting in more energy at a lower speed.
- Less fuel usage.
As mentioned above, Keestrack’s Impact Crushers have a heavier rotor than other brands in the same weight and production class. This results in lower, not higher fuels costs, a more massive rotor is harder to slow down, so as it impacts the material, less energy is being sapped by the impact, meaning less load on the engine.
The Hydraulic system on Keestrack’s Crushers features Load Sensing Pumps that, as their names suggest sense the load on the system and distribute hydraulic power to components accordingly. This feature directs the pumps generate and direct hydraulic power when needed as opposed to most systems that generate and restrict it to components resulting in unused power and fuel usage to produce it. This system saves most machine users around 20-25% in fuel costs, which can be equated to around $10,000 a year.
All of Keestrack’s machinery feature load, level and capacity sensors to determine what the machine is doing at any moment. By detecting what the crushing compartment is doing the machine can adjust the feeder speed to compensate to keep the crusher at its optimal set capacity. All of which is adjustable from the PLC.
- Smart Features.
In addition to the purpose-built cost-saving features, Keestrack Impact Crushers are also high-productivity friendly. With abilities like Wireless Remote adjustability of crushing and screening parameters on the fly as well as simultaneously allowing the operator to track and crush.
Equip2 specialises in Mobile Crushing Machinery, learn more about Impact Crushers or Book a Demo with us by getting in touch.