AFC in Longwall mining

1. ARMOURED FACE CONVEYOR
By Yashwardhan Singh Naruka

3. In longwall coal mining, the coal cut down by the shearer is
transported by the armoured face chain conveyor (AFC), which is
laid across the full face width , to the head entry T-junction, where
it is transferred to the entry belt conveyor through the mobile stage
loader.
The armoured face chain conveyor has large carrying capacity. It is
structurally very strong, bendable and low in body height. It serves
not only as a guide rail for the shearer, but also as the pivot for
support advance.
It transports the coal at a speed in excess of 1 metre/second.
However some face conveyors are running at speeds as high as 1.6
m/s. Generally, the power and capacity of AFC are reflected by the
motor size, pan width and chain size.

4. Apart from the AFC's primary function of
removing the cut coal from the face, its structure
is used for other purposes:
• The edges of the base are used as tracks for the
coal cutting machines (shearers) to run on.
• Tracks or chains utilized for haulage of the
shearer are mounted on the AFC in most cases.
• Troughs and attachments are mounted on the
back plates to carry fixed and trailing cables and
hoses.

5. Major Components of Armored Face Conveyors:
• Drive Head
• Various pans ( line pans, ramp pans, connecting pans, and adjusting
pans)
• Link chains
• Scraper (or flight) bars
• Tail end
• Double acting ram—used for both the support and conveyor
advance.
Auxiliary Devices:
• Face-side ramp plate
• Gob-side spill plate
• Cable handling channel
• Chain tensioning and conveyor anchorage devices

6. DRIVE HEAD
It consists mainly of:
• Drive frames
• Drive units
• Electric motor
• Gearbox
• Fluid coupling
• Chain sprockets

7. Pans
There are a numerous pieces of pans in a
conveyor. They serve as the supporting structure
and moving roadway for the flight bars and the
loaded coal. It also acts as the guide rail for the
cutting machine.
They are of the following types:
• Line or standard pans
• Ramp or connecting pans
• Adjusting pans
• Spilt pans

8. Chain units
The chain unit consists
of the link chain and
the flight bars. The
chain unit must be
very strong and rigid,
and highly wear
resistant because it is
subjected to heavy
external loading,
both dynamic and
static, and to needs
to overcome
frictional resistance.

9. Transfer Methods at Headentry T-
junction:
A stage loader or a curved conveyor is used to
transfer the coal from AFC to the entry belt
conveyor at the head entry T-junction.

10. From the 2005-2006 Joint Coal Board Survey
of Australian Longwall Mines, the following
information about AFC's has been calculated.