MINE VENTILATION
past operating data or a modelling process
conducted by ABB engineers.
Such processes require huge amounts of
processing data and cannot be carried out with
traditional control systems, according to Howden’s
Dello Sbarba.
“Developing mines will often go for a
homegrown solution with a SCADA system,” he
said. “The difference between these SCADA
systems and our solution is that a SCADA system
is limited by the number of hours and
programming you can put in it. Our system is
specifically tailored for the application of
underground mine ventilation meaning the
possibilities are endless.”
The increased number of sensors around mine
sites and the improvement in network
connectivity can boost a VoD system’s accuracy
ABB says
system can already incorporate dispatch
information.
Such machine and system data allows
companies like ABB to create data-driven models
to improve the optimal operating points of a
ventilation system, according to Nyqvist.
“You always want fans and air regulators
operating at the optimal speed,” he said. “We can
now use an algorithm to calculate that and use
sensors for feedback on how well the system
performed in that setup.”
To do this, “the system collects the demand
from gas sensors, or the tagging and tracking
systems of vehicles and people, and matches this
by calculating the optimal operating point of the
fans and regulators”, Nyqvist says
In big installations such as Codelco’s
Chuquicamata Underground mine – where ABB
has installed 250 air quality sensors – this is a
substantial amount of data to integrate.
“We push that data back to the system as set
points and then record the performance with the
flow sensors,” he said. “We check the
performance every 15 seconds to ensure the
system is working optimally all the time.”
These algorithms are generated from either
Highly leveraged
“It’s the flexibility and scalability of NRG1-ECO that
really differentiates it,” SHYFTinc’s Ouimet says.
“You can implement it as an end-to-end complete
process change, or you can implement it as a
scaled setup where you are doing minimal work to
start with.”
The levels of ventilation control are part of this
flexibility.
NRG1-ECO can offer mining companies anything
from manual real-time control that allows them to
manipulate devices through a web interface; timeof-day
scheduling to automatically adjust devices
at specific times; event-based planning where
devices can be stopped/started or adjusted based
The fan blade and turning vane design is at the heart of the performance
of an axial fan, with the fan’s “character” determined by how these two
components are designed and interact, Zitron says. Should a failure occur
on an axial fan, the cause would most likely be the fan blades or the
motor (mostly bearings).
The blade is also the most mechanically stressed component in the fan
assembly, having to endure thousands of cycles at huge centrifugal
forces.
Fan blades have been cast (sand cast mostly) for more than a hundred
years and are still being successfully manufactured this way due to the
ability to produce large quantities of components economically and
without the need for many additional manufacturing steps.
But blade casting is by its very nature fraught with inherent obstacles,
with testing of these blades – both destructive and non-destructive –
showing numerous defects. These defects may cause catastrophic failure
if not ‘caught’ during the quality control phase.
Zitron has recently invested in a custom designed 5-Axis CNC machine
centre, dedicated solely to the development of new fan blades, and
machining of operational/production primary fan blades.
The advantages this technology offers Zitron are numerous and far
reaching, according to the company.
“It gives Zitron the capability to design, develop and test new fan blade
profiles in a much shorter timeframe and at much lower cost than
previously possible,” the company said. On top of that, there is no need
for patterns and moulds to be made for each new blade design, meaning
much more intricate shapes and dimensions not previously possible
through casting can be designed.
New blade profiles are designed using ANSYS and NUMECA CFD
software specific to the fan’s required duty. These blades are then
machined in a matter of days, ready for testing in the actual fan it would
be installed in, at the Zitron Test laboratory.
Another shortcoming of the casting process is the availability and
consistency of castable materials, Zitron said. “With Zitron’s machining
capability, blades can now be manufactured from virtually any available,
machinable material on the market.”
The use of forged, high performance alloys, combined with the
capability to control dimensions to within microns, results in blades
having superior mechanical properties (tensile and yield strength),
greater structural integrity and being lighter than comparative blades cast
from other materials, according to Zitron.
Lighter blades result in lower centrifugal forces acting on the fan rotor,
which in turn negate the requirement for heavy rotors. The rotating
component (rotor and blades) ends up having a lower inertia and mass
also. Bearing life is extended as a result, reducing maintenance costs.
“Another advantage is the superior surface finish that a machined
blade has over one that is cast,” Zitron said. “There is no need for
polishing after casting, which is another action that can introduce
problems such as stress raisers in critical areas when polishing is not
performed with the correct equipment and with due care.”
Due to having identical dimensions, machined blades also weigh the
same for a specific shape. Blades, therefore, do not require weight sorting
for dynamic balancing purposes.
While Zitron says this new process will not replace cast blades in the
majority of the fans supplied, it will add to the existing technological
advances made and used by the company.
88 International Mining | JULY/AUGUST 2020