Qatar National Cement Company uses its first Sandvik rig on Qatar’s largest limestone quarry

Published 2011-11-20 00:00:00

Qatar National Cement Company decided to use a Sandvik DX700 drill rig equipped with Sandvik drill bits for its latest limestone quarry; the first time that the company has used Sandvik equipment.

The first Sandvik DX700 top-hammer crawler drill rig to be purchased by Qatar National Cement Company is working at Qatar’s largest limestone quarry, near to Doha, using Sandvik drill bits, rods and shank adapters to bore to depths of 75ft (22 m).

The rig, drill bits and other equipment have been supplied by Sandvik’s distributor in Qatar, Q-Fab, which also has a maintenance contract with QNCC to keep the machine in service and repair.

QNCC was founded in 1965 and is today Qatar’s prime cement producing company. It is a major producer of Ordinary Portland cement, sulphate resistant cement, hydrated lime, calcined lime and washed sand. The limestone is extracted from the Umm Bab region, on the west coast some 80 km from Doha, and this is also where QNCC’s manufacturing plants are located.

The most recent quarry was opened seven years ago, says QNCC’s Ahmed El-Khazien  .

“To improve our productivity, we decided to invest in the Sandvik machine which is proving to be very satisfactory and our drilling and production has been greatly improved”    

He continues, “Our total output is 5 million tonnes per year, and following a downturn in Qatar’s construction sector we are now looking at a lengthy period of high demand with many new projects underway and upcoming, so we need a high-productivity machine that is also reliable.

“Our main drilling at this quarry is carried out with one rig, so it is always important that we can have confidence in the equipment.”

The DX700, the first in Qatar, was commissioned by an engineer from Sandvik’s regional office in Dubai, which is in charge of all business and customer support in the Middle East.

Training was provided at the same time for Q-Fab’s service engineers and for the three operators who are employees of QNCC, and who operate the rig in shifts.

Sandvik’s service agreement for the DX700 covers both 250-hour servicing and breakdown and repair services, both of which are carried out by Q-Fab engineers from Doha. QNCC staff carry out routine maintenance.

Mr Ahmed El-Khazien  explains that the blasting is carried out every day except Fridays and Saturdays, the explosives being brought in by road from a Ministry of Interior Arms/Explosives Division depot some 85 km from Ummbab .

“We are using the Sandvik rig to drill 3.5-inch holes down to the depth of the quarry floor, which is between 72 and 75 ft (22 m) below the surface,” he says.

“There is no need for us to drill in benches. The limestone is medium grade all the way down, with no real variations. The drilling operation is therefore a routine one, carried out on flat ground, and the combination of rig and bit is, I think very suitable for these conditions.”

The drilling pattern is 3.5 m burden and 4 m spacing.  “This pattern and the use of delay detonators, minimises the vibration and disturbance to equipment in the manufacturing plant and the nearby offices beyond the blasting face.” says Mr  Ahmed El-Khazien.

He elaborates further, “The blasting is designed to produce rock fragments of between 0.8 and 1 m, which are the size required by the crusher.

The DX700 is a hydraulic, self-propelled, self-contained and crawler-based surface rig that has a standard drilling coverage of 17.6 m2 and which uses a Rock Pilot drilling control system that ensures maximum penetration and rock tools service life as well as straight holes.

Q-Fab has been Sandvik’s distributor for Qatar since 2008, and Butch Villanes, Product Manager for Q-Fab’s mining technology department, says that he had initiated discussions with QNCC in the earliest days of the distributorship.

“We really felt that a Sandvik rig and drill bit combination could achieve the productivity and reliability that no other manufacturer could match,” says Mr Villanes. “We went onto the site, and showed QNCC how the specification of the DX700 could improve performance, and demonstrated the reliability and cost-effectiveness of using Sandvik’s own drill bits.

“The company finally decided in December to invest in the DX700.”

At the QNCC quarry, the DX700 is using Sandvik  89 mm RT300 Uniface Retrac  drill bits - a newly launched range of threaded button bits that use one super grade of cemented carbide throughout and a universal face design.  The user needs only to select the best button shape – spherical or ballistic – and open skirt design – regular or retrac – to obtain the best bit for the rock formation; keep blastholes clean during drilling, minimizing re-crushing and ensuring longer service life

“We did an analysis of the soil on the site, and decided that spherical bits were the most suitable,” says Mr Villanes.

“QNCC’s policy is to use only new bits and not to sharpen them, so we are in a position to supply any required number of drill bits as and when required; supplied direct from our warehouse in Doha.” he adds.

The DX700 is using 12 ft lengths of T51 drill rods and a T51 shank adapter. This is the optimal rod size for the 89 mm drill bits that are used in this quarry.  MF rods are ideal for mechanized rod handling as they have no separate coupling sleeve. MF joints are tighter and more rigid than rod and coupling and also transmit more energy into the drill bit, giving both higher penetration rates and straighter holes.”

The three-man quarry team comprises a Filipino, a Sri Lankan and a Bangladeshi operator. According to the Filipino operator, Mr Romeo, there are no obstructions and the drill bits are going straight through the limestone without any impediment.

“We started off slowly so that everyone got used to using the machine,”  he continues, “We were however soon able to get up to a good rate of productivity, and now we are able to drill 10 holes in around five hours.”

“In nine months of working we have had no breakdowns, and the DX700 is proving to be very reliable and productive,” concludes Mr Ahmed El-Khazien.