Excessive fines inside an impact crusher is like sandblasting. Your impactor wear parts such as hammers and wear plates will be chewed up quickly. To counter negative effects from fines mobile impact crushers have a built in pre-screen to bypass the crushing chamber or seggregate fines through a side conveyor.
Over feeding an impact crusher will actually give the opposite effect of what you are probably trying to achieve. You want greater production right? Then over feeding is not the way to do it. Unlike jaw crushers impactors do not run on the choke fed theory. Jaws and cones need to be choke fed as they work on gravity and compression. Where as impact crushers work on actual impact force (inertia) from the rotor and blow bars that impacts the rock. If you are over feeding the chamber you risk boggin down the crusher and limit the crushing force. Mobile impact crushers will self-regulate the feedspeed to counter these effects.
A mobile impact crusher should always be set up on solid, level ground to ensurefor proper leveling and operation. Soft underground such as freshly packed dirt or aggregates will settle during operation, resulting in uneven leveling of the crushing plant. It is critical that the mobile impact crusher is not leveld to one side or the other as this will move the material to one side or the other. This will cause uneven and premature wear on one side of the hammers. Ultimately, it is more important for a mobile impact crusher to be leveled side to side rather than front to back, although both can have adverese effects on performance.
Using the right feed equipment and setup can make or break your crushing operation. Generally speaking, processing chunky material and slabs you want to use an excavator to feed an impact crusher. If the feed material is smaller in size and homogenous a wheel loader will work as well. Your bucket size is the main determinant for feed size. If you use a smaller bucket you will encounter fewer blockages. If the material is frequently oversized, it requires proper prep or upgrading your to a larger crusher.
Materials such as reinforced concrete or asphalt slabs should be sized properly before feeding it into the crusher. If material is too large, it leads to jamming or bridging at the crusher inlet. Generally, the maximum feed size should be 80% of the inlet opening to reduce risk of causing a jam. A hydraulic or mechanical pulverizer or hydraulic hammer can be used to reduce material in size. The pre-processing of material allows you to sort through your material and set uncrushables aside.
Hammers or blow bars wear over time (become shorter) which will increase your closed side setting (CSS). Checking your wear allows you to reset the appropriate CSS, check for damages, and order wear parts in time. If you wear your blow bars all the way down to the rotor you risk major damages and repair costs. It is recommended to open the crusher box once a day to check your consumables and clear your crusher box from objects that got stuck.
Cosistancy is the key to success. Impactors should be consistently fed with material accross the entire with of the inlet opening to increase rock on rock crushing. This will increase production and reduce wear. To achieve a consistant flow of material your process elements feed material, excavator, crushing, and stockpiling need to be in-synch.
Using the right metallurgical composition of hammers for each respective application is critical to achieve low wear costs.
Multi purpose hammers with highly wear resistant ceramic inlays. This type hammer is ideal for operators that process reinforced concrete, large rock, and a large variety of materials.
Cast chrome hammers are harder and more brittal. Thus, more sensitive against impacts resulting from uncrushables. Ideal for crushing asphalt or in secondary crushing applications.
Cast chrome hammers with ceramic inlays are harder and more brittal. Thus, more sensitive against impacts resulting from uncrushables. Ceramic inlays will increase the wear life of this type hammer.
Make sure that the excavator is situated high enough so that the operator can see inside the hopper. This allows for better material control and fewer blockages. However, do not place yourself directly behind the impactor to avoid any injuries from stones rickocheting out of the crusher.
Crushing requires experience. Make sure to get trained properly through the manufacturer or dealer so that you can get the most out of your machine and avoid any damages or injuries.
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