IPCC
Part of the OLC section of the ore transportation
system supplied by Tenova TAKRAF at Codelco's
Chuquicamata Underground project
being conveyed is specified by a shear gate and
the flow of discharged material is defined by
varying the conveying speed. The elimination of
the vertical sidewalls associated with belt
conveyors means less wear and thus reduced
maintenance costs, combined with energy savings
of around 25%.
Two conventional trough conveyors connect the
material discharge of the feeder conveyors with
the loading point of the inclined conveyor, around
900 m away. The tunnel extends some 6,400 m to
the surface and the inclined conveyors overcome a
difference in elevation of 950 m.
As each underground transfer point along the
tunnel requires an underground chamber with
considerable infrastructure, the number of transfer
points was minimised by using an inclined
conveyor section with just two conveyors. This
was made possible by newly developed
components that redefine the performance limits
of belt conveyor technology.
St 10,000 quality conveyor belts from ContiTech
were used for the first time. Operating belt safety
ratings of S = 5.0 required belt connections with a
reference fatigue strength of over 50%. Once
again, new dimensions were achieved - this time
in terms of installed drive power - with 10,000 kW
of installed drive power per drive pulley and
20,000 kW per conveyor.
In cooperation with the drive motor
manufacturer, ABB, Tenova TAKRAF engineers
developed a drivetrain consisting of a 5,000 kW
synchronous motor, membrane coupling to connect
the pulley shaft and rotor shaft and drive pulley .
Maintenance of the air gap between the rotor
and stator is a crucial requirement for the
operation of the motors, with the 14 mm air gap
between the rotor and stator only being allowed to
deviate from the setpoint within small tolerances.
This is because deviations in the air gap reduce
the efficiency of the motor and, if the rotor and
stator were to make contact, it would damage the
motor.
The air gap is continuously
monitored during operation. If
deformations and/or
subsidence in the steel
structure or motor foundations
lead to a deviation in the air
gap setpoint, the stator has to
be realigned. To simplify this
process, the spacing between
the rotor and stator at the non-
driven end of the motor was
fixed by a support bearing.
A membrane coupling
compensates for deformation
of the pulley shaft caused by
belt tension. The adjustable motor frame
facilitates alignment of the motor during
installation and ensures simple realignment if
necessary.
Eccentrics and spindles allow the stator to be
adjusted in all directions. Should a motor fail, it
can be quickly moved into a disabled position by
opening the membrane coupling and adjusting the
spindles. The system can then operate with
reduced power.
The landscape has been shaped by over 100 years
of mining, with, in addition to processing plants,
waste heaps, train tracks, roads, pipelines and
buildings. The challenge was to design an overland
conveyor system that took into consideration this
landscape for its entire length from the end of the
underground tunnel to the processing plant more
than 5 km away. A continuous single flight conveyor
was developed as follows:
n Distance of 5,330 m between the material
loading point and discharge with a difference in
height of 287 m
n Horizontal curves with tight radii (1,600 m to
2,300 m) on more than 60% of the conveyor
length
n Approximately 50% of the conveyor length on
elevated structure with variable lengths
adapted to local conditions for foundations
positioning and with support intervals of up to
96 m.
All loading points were
optimised to reduce conveyor
belt wear. Newly designed
transfer chutes allow wear
plates to be replaced quickly
and easily. A specially designed
TAKRAF maintenance vehicle
travels along the conveyor path,
enabling the conveyor belt to be
lifted and worn idlers to be
safely and efficiently replaced.
At the material discharge
point, a bunker building
provides limited material
storage. Two feeder conveyors remove the
material and feed it to the processing plants.
Three 5,000 kW direct drive motors drive this
conveyor, using a St 6,800 conveyor belt with a
belt safety of S = 5.
McLanahan feeder breakers set for
Indonesian coal mine expansion
US-based McLanahan Corporation says it
continues its long-standing support of Indonesian
coal projects after being awarded an A$4.5 million
contract to supply custom-engineered Feeder-
Breakers to PT Bukit Asam. PT Bukit Asam’s main
sites are the Air Laya, Muara Tiga Besar North and
West & Central Banko mines with a combined
production of over 25 Mt/y.
The contract includes the manufacture,
assembly, supply and commissioning on site for
two McLanahan FB48-50-46 Dump Hopper Feeder-
Breakers and one RFB48-50-49 Reclaim Feeder-
Breaker. The ROM Dump Feeder Breakers will be
handling raw coal. Each machine will be
positioned underneath a 150 t, 12 m long hopper
allowing two 50 t rear dump trucks unloading from
each side of the hopper. All machines are being
designed, manufactured, assembled and shipped
from McLanahan’s Australian factory in Cameron
Park, NSW, where factory acceptance testing will
also be witnessed by the client’s representative.
“It’s a real thrill to be able to showcase our
technology to one of Asia’s most trusted coal mining
companies,” said Chris Knowles, Director of Sales
and Marketing at McLanahan. “As an Australian
OEM, we feel that our experience in developing
equipment focused on safety and ease of
maintenance, along with automation, was a big
factor in our selection. Of course, it helps to have a
partnership with the industry’s best service provider,
PT Suprabakti Mandiri. Pt Supra offers highly trained
local personnel who are able to respond
immediately and meet the needs of the customer.
“Coming off the back of the most successful
year in our history, we see this new project as a
great start to the new year, and confirmation that
our continued investment in the region is well
supported,” Knowles said. IM
Similar McLanahan ROM Dump Feeder
Breakers to those being supplied to PT Bukit
Asam in Indonesia
MAY 2020 | International Mining