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Cementing
partnerships
LIMESTONE
in the LIMELIGHT
The
Middle East's largest producer to boost output again
In
the last issue of Mining & Construction, we focused on a highly
successful cement production operation in Oman. This time, we
cross the border into the United Arab Emirates to visit the Middle
East's largest limestone quarry.
The United Arab Emirates is
a union of seven states lying along the eastern coast of the Arabian
Peninsula, where it juts out into the Arabian Gulf.
Ras Al-Khaimah
is the northernmost emirate and comprises a main town of the same
name, a 56 km coastline and a total area of just 168 square kilometres.
It also has a
flourishing agricultural industry which employs a mostly-foreign
workforce, archaeological sites, beaches, mountains - and the
largest limestone and cement producers in the Middle East.
The Ras Al-Khaimah
Rock Company (RAK Rock Co.) was established in 1971 by His Highness
Sheikh Saqr Bin Mohammed Al Qasimi, Member of the Supreme Council
of the UAE and Ruler of Ras Al-Khaimah. Four years later, the
company bought its first piece of Atlas Copco equipment - a compressor.
RAK Rock's two
limestone quarries, with an area of one square kilometre, are
located in an industrial area 35 km north of the town. In addition
to high-grade limestone supplied to cement plants and the steel
industry, they produce aggregates for concrete and road construction
and rock for breakwaters and other marine work.
| Quarry
Supervisor Pierre Leboutte: "We've had outstanding performances
from the two hydraulic ROC rigs." |
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The location of the quarries,
with the crushing plants and three cement factories, is close
to the deep-water harbour at Port Saqr, which has assisted the
company's export business. In addition to supplying the local
market and nearby cement plants, 50% of the products are shipped
throughout the Gulf region - mainly to Bahrain and Kuwait - and
by bulk carriers to India, Australia, Hong Kong and Taiwan for
the steel industry.
Increased
production
Annual production
is currently exceeding 12 million tonnes of crushed hard limestone
and rock, but this will be increased in the near future to cope
with the extra demands of a new cement factory and other commitments.
The current output
is achieved with the following equipment, facilities and manpower:
A fleet of 12 pneumatic and hydraulic drill rigs, 70 dump trucks
and loaders, 14 crushing plants - with a capacity of more than
4,000 tonnes per hour - and a workforce totalling 650 people.
To achieve this
production, a unique method of transporting material has been
devised by the company. Blasted rock of up to 1 m3 in size is
dumped into a 60 m-deep, 6 m-diameter shaft sunk in limestone.
A 3,000 tonnes-per-hour primary jaw crusher, installed in an underground
chamber, reduces the rock size to under 400 mm and it is then
conveyed through an 80 m-long adit by a 3 km-long high-speed belt,
travelling at 4.6 m/s, which feeds a large stockpile. Material
from the stockpile feeds directly to the crushing and screening
plants. Two ten-hour shifts per day, seven days a week, are worked
at the site. Benches are 20 to 25 m high in the largest of the
two quarries and four drill rigs are used for bench preparation.
Seven rigs operate on production drilling. The rigs are a mixture
of DTH pneumatic and hydraulic top hammer - and there is also
an Atlas Copco Diamec 232 core drilling rig, which explores the
quality of the limestone to help in planning future excavations.
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General
Manager Sami Rida Sami: "Atlas Copco is the preferred
supplier." |
Says Quarry Supervisor Pierre
Leboutte, who has worked in several quarries in the area over
the past 25 years: "The best drilling rigs here are the two
latest arrivals - the Atlas Copco hydraulic crawler rigs ROC 748
and ROC 848. They give outstanding performances."
The single-boom
ROC 848 was delivered two years ago and the ROC 748, equipped
with a folding boom for easier bench preparations, arrived six
months later. Both rigs also have the powerful hydraulic COP 1840
rock drill and the RPC-F and anti-jamming systems, to prevent
the drill string from getting stuck when the drill bit enters
fractured rock.
"I have found
that a very good choice for the drill string is a combination
of T51 rods with 89 mm ballistic bits," says Pierre Leboutte.
"Ballistic rather than spherical bits perform better in our
rock. We achieve high penetration and straight holes that don't
collapse.
"The burden
is always 4 metres and spacing is 5 to 5.5 metres. A row is 15
to 25 holes, with inclination of 80 degrees. We blast one row
at a time, otherwise the fragmentation will be too small."
The present drill
rig fleet can handle the 230,000 drill metres per year that is
required for production of 12 million tonnes. However, General
Manager Sami Rida Sami says: "To cope with the constantly
increasing demand, we are increasing our production every year.
"At our present
level of production, we have limestone for a further 50 years.
But another cement factory will be ready within three years, so
we are again in the process of buying more drill rigs to increase
production. And Atlas Copco is the supplier preferred by our people
who use and service the equipment."
Quality
factor
Nazeer Sibtain,
who is in charge of the site workshop, says: "We have 135
people working with preventive maintenance and service of all
equipment in the quarries, and each unit of equipment has its
own log book so we can easily see the 'built-in quality' factor.
| Service
Manager Nazeer Sibtain:"We can easily see the built-in
quality factor." |
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"We take care
of all the production equipment with good support from Atlas Copco.
We can handle repair work on the rock drills and the rigs - whether
they are old pneumatic models or new hydraulic units - and everything
else. The availability and distribution of spare parts from Atlas
Copco is good, too."
ROC 848 rig operator
E.M. Noushad comments: "I was previously operating an old
DTH drill rig, but this machine is much better. It has a better
performance, I get better support from the built-in features for
controlling the drilling operation - and an excellent air-conditioned
cabin."
Quarry Supervisor
Pierre Leboutte knows exactly what he wants. He says: "When
we increase drilling capacity, I want another ROC 848."
After M&C's
visit to the quarry, Pierre's wish came true. RAK Rock now has
another ROC 848, which will be at the site in November.
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