2016
IN ASSOCIATION WITH
BULK HANDLING
Rainer Kahrger
Early in his career, Structural
Engineer Rainer Kahrger realised
that belt conveyors are intrinsic to
virtually all continuous material
handling operations. Over the past
40 years, his achievements in
material handling have altered the
approach to belt conveyor design
today. Retired from TAKRAF, Rainer continues
to lay the groundwork for the future of
innovative design and construction of conveyor
systems.
During his tenure as CEO and President of
TAKRAF, Rainer led the design of two world
record-setting projects in bulk material handling:
the largest capacity downhill regenerative
conveyor and the longest single flight conveyor.
The first project involved the largest capacity
downhill regenerative belt conveyor and first
high capacity leach pad bucketwheel reclaimer.
High in the Atacama Desert of Chile is the El
Abra mine. In 1996, TAKRAF designed and built
the largest capacity downhill regenerative belt
conveyor system. The 8,600 t/h, 9.5 km long
overland conveyor descends over 500 m in
elevation from the mine to the crushing circuit,
during which time the vertical drop is used to
regenerate 5,500 kW of power. The system
employed the strongest belt available at the
time with a strength rating of ST6800 N/mm and
revolutionary splice efficiency greater than 50%.
Subsequent to the world record-setting downhill
belt conveyor is the first “racetrack” or “on/off”
dynamic heap-leach system developed by
Rainer and his team. This innovative and first,
for its time, high capacity 6,300 m3/h leach pad
bucketwheel reclaimer, operating in conjunction
with mobile stacking and reclaiming conveyors,
was developed and put successfully into
operation. The same general design concept
was replicated, a couple of years later, at the
Radomiro Tomic mine and, most recently again,
at the Antucoya copper complex.
This arrangement has become the standard in
the (oxide) copper industry.
The belt conveyor, stacking and bucket-wheel
reclaiming system enables high capacities of
copper ore to be leached and the “spent ore” to
be discharged, occupying a minimum footprint
and minimising the use of sulphuric acid (inventory),
thus resulting in a most economical system.
At the Henderson (Climax) Molybdenum mine in
Colorado, USA, Rainer was instrumental in the
design and installation of the longest single flight
belt conveyor in the world. Designed to the
lowest known running resistance ever
measured (DIN f-value below 0.01), the 17 km
long single conveyor was installed and commissioned in 1999. This conveyor system replaced a
train arrangement which had, by then, become
economically unsustainable. The single flight
conveyor, part of a system of three conveyors,
was essential to the client’s requirements for
reduced environmental impact.