Quarry owners and operators alike often discuss what's better to feed a Mobile Screen or Crusher, a Loader or Excavator? This is our take on comparing the pros and cons of a Loader and Excavator.
For Mobile Processing Plant there are only two practical options: a wheeled Loader or an Excavator. For larger fixed plant's you can also feed directly from a dump truck, but that's not applicable in this case.
By understanding the relevant differences of loading a Mobile Plant with either of these machines, we hope this article will help you in your selection of machine to feed the plant.
Wheel Loader vs. Excavator
The hopper size may quickly rule out a Loader, does your plant have a hopper big enough or wide enough to accommodate a Loader bucket of material?
A Loader dribble feeding a plant is inefficient due to its underutilisation. Whereas an Excavator has a smaller bucket and the machines hopper size will not be a problem for all but the tiniest of Mobile Plant.
Distance to feed material
If the feed material is next to the hopper an Excavator or Loader can feed the plant fairly efficiently due to its proximity. However, if the material is any distance from the plant, only a Loader will be of use to transport the material to the plant. Of course, consideration should be given to moving the Mobile Plant closer to the material for added efficiency.
The throughput of the Mobile Crusher or Screen can determine what to load with and if two machines are needed. If high enough, the work required around the Plant and Quarry will require two machines, either two Loaders feeding and taking away material or an Excavator loading and a Loader taking the material away.
For lower output, just one Loader feeding and removing material will be enough.
Also, to consider when purchasing a Loader or Excavator is other work to be undertaken around the Quarry such as Truck Loading, Clean Up and Extraction.
We find that Mobile Plant fed with a Loader have increased wear as they tend to be fed with spikes as it's not consistent or fast enough to keep it choke fed. Choke feeding a plant means there's always material ready to enter the chamber or screen, reducing wear as it won't be running empty, or with material rattling around. Choke feeding is particularly important for crushers as rock on rock crushing is 'free wear' and part of the crushers design.
Material consistency and spec
When the tonnage of throughput goes up, an excavator feeding the plant is best for consistency. A consistent feed increases pre-screening efficiency and end product sizing as it won't have those empty periods with load spikes.
Generally, an Excavator will be sitting up on the material or pad and will be running at low load(as long as the pad is level). However, a Loader will require a ramp to reach the hopper equating to more fuel burn as the machine will come under high load going up the ramp with a full raised bucket.
A Loader also takes more movements to feed a machine than an Excavator, even with material next to the hopper.
Visibility and control
With an Excavator sitting on a pad above the plant and hopper, the operator will have good visibility over the processing plant and crusher inlet at all times. He will be able to monitor the whole plant visually and easily control any of the adjustments at any time with a wireless remote control.
However, when loading with a Loader, operators have restricted visibility and control. When loading, operators will be reaching up from the ramp and will not be able to view the crusher inlet or the feed hopper/pre-screen. Also, when they're away getting more material, they won't have visibility of the machine or be able to make adjustments quickly.
Which should I choose?
The answer differs between each operation based on the points above. Your answer could be different from a similar Quarry, based on your requirements.
Which option has the lowest cost per tonne? After working and seeing so many Quarries using Loaders and Excavators around the country, we find in general the Excavator is better than a Loader, due to it's higher placement, consistent hopper loading and in general faster cycle times.
When making your decision, take a look at the above list of factors, calculate the cost of each machine overall and how that affects your per tonne cost.