OPERATION FOCUS- GOLDEN STEPPES_proof 26/10/2016 10:14 Page 1
OPERATION FOCUS
Golden steppes
Paul Moore visited Muruntau, not
only Asia's largest but arguably
the world’s largest gold mine; and
saw despite its remoteness how
state of the art technology has
been applied there
he Muruntau gold mine in Uzbekistan is
owned and operated by state controlled
company Navoi Mining and Metallurgical
Combinat (NMMC), with the mine located in
Navoiy Province near the town of Navoi in the
valley of Zarafshan, over 360 km south-west of
the capital Tashkent.
Chief Engineer, Atabek Ravshanov told IM
during the visit: "Not just for NMMC but globally,
Muruntau is unique. It is the largest mine in
central Asia and one of the largest in the world.
At 570 m depth plus, the efficiency of the pit
depends therefore on transport and logistics."
The mine uses a fleet of mining trucks but
combined with an in-pit high angle conveyor
system, so the trucks do not actually have to
leave the pit during production. Muruntau has
several conveyors but the main high angle
conveyor is one of only a few true HAC systems
in the world, and definitely the longest and
steepest, having a 37° angle for the long inclined
part and being 3 km in length. Initially the HAC
was designed to work only for ore transport, but
following a series of upgrades can now handle
both waste and ore as required. The mine has a
dedicated waste conveyor as well, but the high
angle conveyor was converted to handle both ore
and waste to add production flexibility. The high
angle ore conveyor reaches down lower into the
pit than the waste conveyor, so it is often more
efficient to use it for both as it involves less truck
travel distance.
The mining production rate of both waste and
ore combined at Muruntau is some 50 Mm3/y,
which equates to over 120 Mt/y, with a waste to
ore ratio of about 1:1, so about 60 Mt/y of each.
While actual gold production figures are not
released, it is consistently over 2 Moz/y with
reserves estimated at 170 Moz including past
production since surface mining began in 1967,
the deposit having been discovered in 1958. The
pit now measures about 3.5 km by 3 km and has
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10 International Mining | NOVEMBER 2016
a current mining depth of almost 600 m, which is
planned to ultimately be extended beyond 1,000
m. The mine operates two 12 hour shifts with
shift changes at 0700 and 1900. Power comes
from a large coal fired power station in Navoi.
In terms of where development stands as part
of a long term plan, the mine is currently coming
to the end of Step IV, which began in the early
1980s and of which the high angle conveyor
addition formed a key part; with feasibility
studies being conducted now on Step V to
maintain the current levels of production, which
will increase the pit depth and width. The goal is
to push back the entire pit perimeter, with the
angle of the new pit walls in different areas
being calculated by the Navoi State Mining
Institute using Micromine Pit Optimis ation.
Currently the lower levels have a bench height of
10 m with the upper benches as high as 50 m.
There are seismic monitoring stations at three
points in the pit of Russian model Delta Geon-02.
Initial plans would have Step V taking mining
production through to 2024 and a decision on
the plan is expected soon. Ravshanov states:
“Every mining step is based on a schedule that
allows for a minimum quantity of ore production.
As at other mines, we set an overall goal for the
years’ production, which is then broken down
into monthly and daily goals which are assigned
to the equipment fleet – every machine has its
own daily goal and is monitored using high
precision GPS. After every shift the machine
reports achieved production figures.”
Machines are allocated based on both
availability and priority by the shift boss to either
waste or ore; and based on conveyor availability
and conveyor maintenance is carried out in two
hours per 12 hour shift. Twice a month there is
more major conveyor maintenance and only one
operates.
IM also spoke with Sergey Lunin, the Mine
Manager. “The Muruntau orebody is very
The high angle conveyor at Muruntau is unique
in both steepness and length
complex, with the gold grade fluctuating a lot in
different horizons so we employ very selective
digging where needed based on the geologists’
block model and our exploration drilling.”
The Muruntau orebody is a complex
stockwork that continues at depth, and two
vertical shafts have been sunk with lateral
development underneath the pit well advanced
and being managed by the NMMC geotechnical
team. The options to go with underground
workings in conjunction with pit deepening or to
go with the open pit only are being considered
based on economic conditions along with new
mining technologies such as continuous mining
options underground. The underground workings
also serve as a method to pump out water from
the pit bottom via underground sumps.
Mining technology and method
There are actually two adjacent pits at Muruntau,
Muruntau itself and next door the Mutinbay pit,
both of which are currently distinct but will join
together in one Muruntau pit over the next three
years. The Muruntau pit came first and is much
larger, its production being about three times
that of Mutinbay at present. Both exploit the
same orebody which runs in a north south
orientation along the Muruntau-Daugyztau shear
zone.
Mutinbay began production in 2009. The ridge
connecting both pits (composed of both ore and
waste) means the fleet is mobile between the
two so trucks and other vehicles can be moved
from one to the other on the 4.27 km link road,
opened in 2015.
Muruntau has the HAC and sizer as the main
production line but also has two other crushers,
while Mutinbay has its own crusher and
connecting conveyor. The HAC aside, the other
main Muruntau conveyor is fed by these three
other gyratory crushers and connecting
conveyors and its main flight is 7 km in length
with a 12° angle. The first gyratory was bought
from Russia but the other two were developed
and built by NMMC.
The mining fleet consists of some 60 larger
BELAZ trucks (35 in Muruntau on average and 25
in Mutinbay on average) mainly of 130 t 75131
and 7530 Series 220 t capacity types; together
with 30 loading tools, including 26 IZ-Kartex EKG
rope shovels of various models, including EKG10, EKG-15M and two new EKG-20K machines, as
well as two EX3600 Hitachi hydraulic excavators
and two O&K (now Caterpillar) RH200 hydraulic
excavators. The mine told IM that the EKG-20
machines have been very productive in both ore
and waste movement. There are also 25 smaller
55 t capacity BELAZ trucks and a few Cat 789C