DRIVES AND GEARS
T aking on torque
ABB GMDs are equipped with dozens of
sensors to protect them and help mining
operators run them smoothly
Water and moisture ingress can potentially be
From huge gearless solutions
for the largest conveyors and
mills down to banks of VSDs
in process plants, drive
systems are at the heart of
all mining operations,
reports Paul Moore
earless drives are becoming more
prevalent in the mining industry
especially at the top end of bulk
handling and milling markets. Gearless mill G ABB has sold more than 130 units in 23
countries. “We are investing a lot in the ABB
Ability™ platform and also improving our
existing GMDs to make them even better in
drives (GMDs) are now the grinding solution of
choice at mines for large mills characterised by
higher-capacity production coupled with low ore terms of predictive modelling,” says Perrucci.
“ABB is also working on digital twin technology,
using augmented and virtual reality (AR & VR)
grades. By eliminating bolt-on mechanical
components such as ring-gears, pinions,
couplings and gearboxes, GMDs offer ore for training and maintenance.
“This will allow us to build up a virtual
picture of the GMD system and environment so
that maintenance can be carried out in the
mixed reality platform before it is applied to the
producers unrivalled availability, efficiency and
durability, while reducing OPEX.
“Both ring-geared mill drives (RMDs) and
GMDs can be employed to drive autogenous
(AG), semi-autogenous (SAG) and/or ball mills,”
says Marcelo Perrucci, Global Product Line
Manager, Grinding, at ABB. “The applications
may be the same, but the challenge now is to
develop bigger drivetrains with the power to
drive these larger grinding mills – and this is
exactly where GMDs come into their own.”
Unlike more traditional ring-geared mill
drives – where a ring-shaped gear encircles the
mill and drives it through one or two pinions
followed by conventional motors – GMDs work
by mounting rotor poles directly to the mill body
and surrounding it with the stator ring, meaning
the mill itself is incorporated into the motor.
The necessary torque to turn the mill is
transmitted between the GMD motor and the
mill via the magnetic field in the tiny air gap
between the stator and rotor. Because this type
of motor system requires no gearing or direct
contact transmission, GMDs boost efficiency by
reducing frictional losses, while fewer mechanical
critical components means less maintenance
downtime is required due to wear and tear.
“GMDs offer the highest power and
availability compared to other driving methods,”
confirms Perrucci. “Efficiency gains are possible
by eliminating mechanical components that may
fail and add unexpected and costly bottlenecks
in the production process.”
Since the first GMD was delivered in 1969,
34 International Mining | NOVEMBER 2019
a significant issue in ring motors, especially at
sites with high levels of precipitation and
humidity. In 2005, ABB modified its insulation
system and, more than 100 machine years and
six million operating hours later, no major
problems have been reported.
“Our heat exchangers – located in the cooling
box structure – are solely installed on the
bottom of the motor, for example, meaning
there is no risk of water ingress elsewhere,
whereas in non-ABB GMD designs the cooling
boxes are placed around the stator, increasing
the risk of water leakage,” explains Perrucci.
Siemens delivering gearless
solution at Quellaveco
Conveyors are an increasingly important
gearless drive market. Powered by Siemens’
new gearless drive technology, thyssenkrupp’s
high-capacity overland conveyor will access one
of the world’s largest copper deposits in Peru.
The Anglo American Quellaveco mine contains
approximately 7.5 Mt of copper in ore reserves.
With the rugged landscape in Quellaveco,
actual machine.”
In terms of recent big orders, ABB has
partnered with Kaz Minerals to supply GMDs for transporting the primary crushed ore requires
durable and efficient technology systems. By
employing Siemens’ technology on this project,
its Aktogay and Bozshakol mines in Kazkhstan.
ABB was awarded a multi-million contract to
provide a 28 MW GMD for a 40 ft SAG mill and
two 22 MW drives for a pair of 28 ft ball mills at thyssenkrupp’s new conveyor system will
transport 127,500 t of primary crushed ore per
day from the pit to the stockpile adjacent to the
Aktogay, and three identical systems at
Bozshakol.
Real time monitoring & maintenance
Using the ABB Ability™ cloud platform, GMD
operators can access key system parameters,
gathering and collating real-time data from
sensors in the system, everything from
insulation monitoring to status of the air gap to
the temperature of poles and windings.
Every hour of unplanned shutdown in a mine
can cost the operator hundreds of thousands of
dollars. Predicting when key parameters will
reach critical levels and halt production is
therefore crucial.
Using data sets collected from the GMD that
are processed by specialised algorithms in the
ABB Ability™ Cloud platform, together with ABB
engineers, critical situations can be predicted
and then timely notify customers in advance,
avoiding costly downtimes.
“We have reports from customers that almost
100 hours of downtime has been avoided by using
this proactive approach to servicing,” says
Perrucci.
copper concentrator. Vast sections of the
overland conveyor must traverse from one valley
to another through a 3.2 km long tunnel. After
exiting the tunnel, the conveyor will pass over
hilly terrain before feeding the stockpile.
Compared with the combination of high-
speed motor and gearboxes otherwise used in
belt conveyor systems, the gearless drive
solution offers a range of benefits. The size of
the motor is not limited anymore by the size of
gearbox, thus eliminating the necessity to
install multi-motor drives. The required belt
driving power can be provided with one drive
per drive pulley. This means that the number of
switchgear enclosures could also be scaled
down, saving space and weight within the e-
house. The elimination of a whole series of
mechanical and electrical components increases
the reliability and efficiency of the overall
system by between 3-4%. Another important
factor is that the maintenance requirements of
the drive system have been significantly
reduced. This is important as gear maintenance
work alone can account for up to 5% per year of
the original investment volume for the gears
thyssenkrupp’s overland conveyor will be