Introduction
Feeders, which include Vibrating Plate, Apron, Reciprocating Plate, Drag Chain and Belt, are used universally in ROM raw coal processing operations to;
- Accept high volumes of bulk ore
- Allow surge capacity between bulk ore deliveries
- Deliver the ore in a controlled manner to the primary sizing equipment.
Most ROM coal circuits include a type of Feeder and Sizer. The type of Feeder chosen for the application is dependent upon the type of feed, the type of primary crusher and the method of delivery to the hopper. Factors effecting the feed include material top size, bulk density, percentage and type of fines, clays and moisture.
A McLanahan Feeder-Breaker is a Feeder and Crusher in one compact, low-profile, horizontal unit, and therefore will take up less vertical and horizontal footprint than a Feeder and Sizer.
Feeder-Breaker Benefits
- Typically, a Feeder-Breaker will require less power to operate than a Feeder and Sizer combination.
- Oversize rocks in a Feeder-Breaker can be reversed through the rear door but can often get stuck in the Feeder’s head chute, making it very costly to remove.
- Feeder-Breakers are, in all cases, shorter and have a much smaller footprint for the same capacity than a Feeder and Sizer combination.
- Feeder-Breakers are less expensive than a Chain Feeder and Sizer combination, both in equipment and infrastructure costs.
Infrastructure
The infrastructure requirements will differ depending on the type of Feeder and Sizer chosen. The Feeder-Breaker is often the most cost-effective option.
The retaining wall is a major capital cost consideration. As the retaining wall height increases it’s costs increase exponentially, along with the costs of the elevated ROM pad. With a Feeder and primary Crusher installation, generally the retaining wall height is significantly higher than for a Feeder-Breaker with an equivalent ROM hopper capacity.
To fit two machines in a ROM station, the Feeder is typically designed on an angle. This increases the length of the Feeder to obtain the necessary height to feed into the Primary Sizer chute. With this design the ROM hopper capacity is reduced, and the Feeder and the support structure costs are increased.
By using the same wall height as the above example, it is possible to create two stages of crushing by inserting a Feeder-Breaker as the primary crusher.
Dozer push type Feeder-Breakers also offer cost savings over Feeder and Sizer designs as they have a reduced height for the primary crushed product.
Perceived weaknesses
There is a perception that Feeder-Breakers have difficulty in gripping and processing large lumps. In the past other suppliers provided poorly designed machines with small diameter breaker heads or even breaker barrels which caused this issue. A McLanahan Feeder-Breaker has neither of these design flaws.
Another perception is that Feeder-Breakers allow slabby material to be passed to the secondary crusher. While it is possible for slabby material to pass if the breaker head is raised high enough, in practice a correctly designed breaker head produces the correct sized feed for the secondary crusher. On McLanahan Feeder-Breakers the risers on the flights interact with the breaker picks to ensure long slabby feed lumps are efficiently broken up.
Feeder-Breaker Features
A well-designed Feeder-Breaker includes;
- Tungsten carbide tipped picks. They are relatively inexpensive, easy to replace, and are low-wearing crushing components
- Automatic chain tensioning
- Hydraulically operated rear door for ease of access
- A correctly designed breaker head
- Side and top access doors
- Discharge access and hydraulically actuated laydown door
- Bolt-on chain hold downs, plug welded Q & T steel deck plates with Q & T bolted side and skirt plates.
These all add to the maintenance friendly and time-savings features of the McLanahan range of quality equipment.
Learn more about how to select the right sizer for your project here.
