COMMINUTION
hen Brunel Corp, a leader in torque-limiting technologies, needed reliable power
transmission components for use in a custom gear turning and locking (TL) system for
FLSmidth, it turned to Twiflex and its Twiflex TL system.
The Twiflex TL system, to be installed on a new dual-drive, 2,000-kW high pressure grinding
roll (HPGR) at a gold mine in Turkey, is used to slowly turn and lock the twin grinding rolls,
allowing for the safe refurbishing/replacement of worn tyres during scheduled maintenance
shutdowns, according to Twiflex.
“The mine operator can move the TL system between the two roll driveshafts when
maintenance is required,” Twiflex said. A chain/sprocket inching drive, which was time-
consuming to install and cumbersome to operate, was previously used to perform this task.
To meet the application requirements, Twiflex, part of Altra Industrial Motion, supplied a TL
system comprised of a turning gear, which engages with a 1,000 mm diameter solid steel
gearwheel mounted on the output flange of a Brunel torque limiter. The turning gear includes a
1.5-kW motor with a gearbox to produce a breakaway torque of 3,760 Nm and an output torque
(continuous turning, bi-directional) of 1,580 Nm at a nominal turning speed of 5.2 rpm. A
frequency converter is supplied to allow the turning speed to be controlled between 1.3-5 rpm.
The bi-directional turning gear is designed to turn the grinding rolls in either a clockwise or
counter-clockwise direction and is rated for continuous operation, according to Twiflex. A hand-
operated clutch mechanism is used to engage and disengage the drive with a limit switch fitted
to indicate its position.
The system includes a manually operated tooth-locking device with a rated torque of 52,000
Nm that locks the gearwheel in place. The status of the locking device is monitored using limit
switches (ie lock on/lock off ).
The Twiflex TL system also included an operation panel for local control of the turning gear. A
plug-in handheld corded pendant was also supplied for remote control of the turning gear close
to the equipment.
“Specially-designed safety element modules were introduced by Brunel engineers for use on
their JSE torque limiter to provide protection from damage to the U-joint shaft, planetary gearbox
or grinding rolls,” Twiflex
said. The overload can
come from either
direction: 1) obstruction
in the gap between the
rolls, or 2) short circuit
of the medium voltage
AC VFD causing the
motor rotor to lock up.
Based on the SE30
torque elements from
Bibby, also part of Altra,
the modules set to 169
kN tangential force
automatically disconnect
in the event of oversized
tramp metal/other
The Twiflex TL system is used to slowly turn and lock the twin
jamming-type events or
grinding rolls, allowing for the safe refurbishment/replacement
drive short circuiting.
of worn tyres during scheduled maintenance shutdowns,
according to Twiflex
Brunel engineered and
delivered a unique
packaged solution that incorporated all the components into a tight footprint assembly, Twiflex
said. The ability to single-source the power transmission components required for this
application from Altra brands, Twiflex and Bibby, saved Brunel much time and effort, Twiflex
added.
W
n Francis Fournier (COREM) ‘IntelliCrush:
Advanced artificial intelligence tools to design
eco-efficient comminution circuits’;
n Gillian Holcroft (Canada Mining Innovation
Council) ‘CAHM – A Disruptive Grinding
Technology that will Significantly Reduce
Energy Consumption in Comminution’;
66 International Mining | APRIL 2019
n Tracy Holmes (Jenike & Johanson) ‘Targeted
Microwave Heating Rocks! A Step-Change
Energy Reduction in Comminution’;
n Saeed Karimifard (Motion Metrics) ‘AI-Driven
Dilution Control (Mine to Mill Optimization via
Ore Sensing and 3D Imaging)’;
n Caroline Olsen (COREM) ‘Development and
Demonstration of HPGR Grinding and Novel
Classification to Mineral Separation Circuit
Feed Sizing in Replacement of Ball Milling’;
n Todd Parker (Blue Spark Energy) ‘Crush Pulse’;
n Mark Sherry (iRing) ‘Eliminating the Crusher
and Grinding Requirements: Using the Blast to
Create the Required Fragmentation’, and;
n J Lyall Workman (Barr Engineering) ‘Blasting
Down Crushing and Grinding Energy
Consumption’.
iRing, the underground mining ring blasting
solutions provider and one of the semi-finalists,
told IM that the most effective way of reducing
the amount of energy consumed during the
comminution process is to start upstream.
As Chris Preston, Vice President of Research
and Development at iRing, said, “If you get the
front end of the process organised, the savings
are going to be huge down the line.”
iRing and its AEGIS blasting pattern design
software is leading a group called the Paradigm
Shifters in The Crush It! Challenge.
The Paradigm Shifters consists of iRing, Nexco
Inc, Boart Longyear, Paige Engineering, Seneca,
Maptek and Bomon Capital.
Preston explained the group’s end goal: “Our
focus is to make sure drilling and blasting
becomes a precision process – similar to a CNC
(computer numerical control) process for
machining parts,” he told IM.
“The Paradigm Shifters’ point is to eliminate
the crusher underground, which essentially is
there to take care of mistakes made during the
blasting process,” he said.
Preston is confident the group can do this by,
first, setting the blast hole design in AEGIS to
target precise fragmentation. Boart Longyear will
deploy recently developed high speed diamond
drilling technologies and instrumentation
solutions to quickly and accurately drill and
validate high-quality blast holes – using
significantly less energy – and then Nexco, Paige
Engineering and Seneca can produce and load
the energy-variable explosive product in said
holes. Following loading and blasting, Maptek
lends its 3D laser scanner capabilities to the
process, verifying the fragmentation results by
scanning the muckpile and producing a 3D point
cloud that can be analysed for a measured
fragmentation distribution.
This integrated process is all-important to the
Paradigm Shifters’ aim of eliminating the need
for an underground crusher.
Troy Williams, Vice President of Development
of iRing, told IM: “We have been finding that
there is a lot of good engineers that can design
the blasting patterns that they need but the
process often falls down on execution – the
drilling is done poorly with almost no
management oversight.”
iRing estimates the elimination of primary