HIGH PROFILE
Digital production drilling
Jukka Naapuri, Product Manager for Underground Top
Hammer Production Drills at Sandvik Mining & Rock
Technology, outlines key trends in longhole drilling in
mining
Sandvik says its DL421 is the most popular
longhole drill in the market in mass mining, in
4 x 4 m or larger cross sections, providing a
proven track record in drilling capacity, hole
accuracy and productivity. This machine is part
of PYBAR’s contract fleet
tarting with autonomy, equipped with fan
automation and teleremote drilling
operation, the first automated top hammer
longhole drills were delivered in the world market
25 years ago. For the last five years most of the
delivered units have been automated, while the
use and full utilisation of these features –
including boom movements between holes,
alignment, rod handling and data management –
has started growing.
Automation in drilling can only fully be utilised
for productivity increase if all the phases in the
cycle can be automated, including bit changing.
Discussion on multi-fan automation has also
started, where the unit would move automatically
(or in remote control mode) between the fans; for
this the drill would need to know its position in
the drift so that carrier navigation can be carried
out accurately. However, today the focus is still in
completing one fan or drilling plan automatically,
including drilling, rod handling, bit changing, hole
alignment and boom movements between the
holes; drill plans are wirelessly transferred to the
drill and the as drilled data back from to the
office. Mines would like to ensure that the holes
in the stopes are drilled accurately according to
the plans and as-drilled data is available for
planning explosives charging and blasting, and
for further mine planning.
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28 International Mining | JULY 2019
Battery electric longhole drills
As the longhole drill spends long periods of time
in the production drift and because of the often-
short tramming distances, this application has
not been a focus for battery electric systems.
With multi-fan automation, however, battery
tramming can improve productivity as the carrier
can fast and accurately be moved from a fan to
fan.
Utilising the solutions and feedback with
development drills, the first battery tramming
capable DL422iE longhole drill will be introduced
in the global market in 2020; while the tramming
range is up to 4 km in 1:7 ramps, the energy for
tramming is obtained from onboard batteries with
sodium-nickel chloride battery chemistry. The
batteries can be charged via mine electrics during
drilling, while in drilling the unit utilises the mine
electrical system. Active power compensation can
be used for supporting the operation in weak
electrical networks. The system features
improved product safety, productivity and
reduced operating cost.
Offering development in changing
mining environment
Mines today are operated in ever more
challenging conditions in terms of altitude,
ambient temperature, location, and mine water
and air supply; at the same time more complex
and smaller orebodies need to be mined
economically. In general, the underground mines
are requiring solutions with which they can
increase mine outputs at lower operating cost,
and mine safer; they would also like to ensure
sustainability during the mine lifetime through
technologies.
Equipment suppliers are working together with
customers to ensure user feedback is collected
from worksites and utilised in product
improvement processes, to improve machine
reliability and to lower the operating cost.
Feedback from minesites where the conditions
are difficult, help in introducing solutions, with
which the operating range of longhole drills can
be expanded eg into high ambient temperature
and extremely harsh water environment. If the
time-to-market with such solutions meets
customer requirements, product competitiveness
and unit sales volumes are ensured or even
increased.
The industry is continuously putting an
increased amount of effort in maintaining suitably
qualified workforce at remote minesites, while
utilisation of automation, data management and
remote control is allowing increase in productivity
and managing control of the mine processes
better. The ability to monitor drilling equipment
remotely has become an important issue when
planning of service and maintenance, or in the
fleet management processes.
Drilling methods and hole accuracy
Top hammer longhole drills are designed for
drilling Ø51…115 mm production holes up to 50 m
in depth, and the method features good energy
transfer and high net penetration rates. As the
rock drills are hydraulically operated, the energy
efficiency and sustainability of the method are
good. With the introduction of tube rods, hole
accuracy of top hammer drilling is approaching
the levels of the ITH drilling. With the introduction
of drilling automation and teleremote operation,
productivity has been increased and the
operating cost levels are competitive.
In-the-hole (ITH) longhole drills use
compressed air for drilling power and the method
is highly versatile in underground applications;
Ø90…445 mm single holes up to 80 m in depth in
production drilling and service support, up to
Ø762 mm raises in stope development with
reaming, while the net penetration rate is
constant over the hole depth. As the diameters of
the bit, hammer and the pipes are close to each
other, it is relatively easy to achieve good hole
accuracy and hole flushing. The noise levels are
low as the ITH hammer follows the bit in the
hole.
Mechanisation in ITH longhole drilling has
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