New drill brings extra power to Fujairah site

A specialist drill and blast contractor has taken delivery of its fifth Tamrock 700-2 surface drill rig in less than three months, bringing its total Tamrock fleet to eleven rigs in just five years. Construction Week learns more.

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By  Colin Foreman Published  April 2, 2005

New drill brings extra power to Fujairah site|~||~||~|UAE-based drill and blast contractor, Technical Drilling and Blasting Co., has taken delivery of its fifth Tamrock Ranger 700-2 surface drill rig in less than three months. The latest rig is fitted with Sandvik Rock Tools drilling rods and bits and has been put to immediate use in a new mountain-top quarry in Fujairah. Technical Drilling and Blasting Co. specialises in drill and blast contracts for numerous major quarries throughout Fujairah, and also undertakes some civil engineering projects including pipelines across the region. It is the quarries, however, which provide the biggest test for the company’s fleet of Tamrock rigs and Sandvik Rock Tools, working in ground conditions described as amongst the toughest in the world. The gabbro rock with a density in excess of 3 t/m³ and a crushing value of 10 is in high demand for asphalt and concrete production plus rock armour for breakwaters. It is highly abrasive and has 61% silica content. Since the formation of Technical Drilling and Blasting Co. in 1998, the contractor has been using two of Tamrock’s CHA660 surface rigs with great success. According to Tom Ross, the deputy manager of Technical Drilling and Blasting Co., both have provided more than 13 000 hours of operation each. As Technical Drilling won additional contracts with new quarries, it recognised the need for a new rig and opted for the slightly larger production model, the Ranger 700-2. With the current ‘boom’ in aggregates to meet demand for construction projects across the region — especially in and around the emirate of Dubai — the contractor placed orders for a further eight rigs with local distributor Dynatrade, taking delivery of the last five over the past three months. “Over recent years we have seen a change in market demands,” says Ross, adding, “There is a trend today for a more powerful rig and bigger diameter holes calling for a larger production rig. Clients are also demanding an improved shape and size of aggregate.” According to Ross, at least 85% of holes drilled today are 89 mm diameter, whereas in the past hole diameters were generally 64 mm and 76 mm. The Tamrock 700-2 with its European spec is proving the ideal rig, particularly when fitted with 89 mm flat face ‘Retrac’ bits from Sandvik Rock Tools. “We have found that the new rig provides us with a greater production output and a high degree of accuracy,” says Ross, continuing, “Drilling larger diameter holes with thicker rods, also from Sandvik Tamrock, means less breakages.” The new rig features a rear-mounted power pack which effectively counterbalances feed and boom assemblies, thereby providing an inherently more stable drilling platform. A hydraulically operated winch complete with cable tightness automatics helps to ensure maximum operator safety. The turntable mounted articulated boom and rock drilling assembly offers 120º arc movements and a massive 17.6 m2 drilling area coverage. This configuration provides improved drill location range even at the most acute angles. With a major emphasis on operator comfort and safety, the cabin features laminated windows and both roll over/falling object structure protection to the appropriate ISO standard. Excellent all-round visibility of the drilling area, together with air conditioning, filtered air intake and soundproofing up to 80 dB(A), help to provide the operator with an excellent working environment. A single multi-function joystick proportionally controls the drilling rationale and a number of standard operations are automatically implemented, allowing the operator to focus on the work in hand. With its latest Ranger 700-2 surface drill rig, the Technical Drilling and Blasting Co. has started work on a 201 m-high peak in the foothills of the Hajar Mountains in Fujairah. Work on the Doha quarry, developed by recently formed Great Lakes Development Corp, started at the beginning of the year, with one of the first jobs involving removal of the beacon on the flight path to nearby Fujairah International Airport. With expected reserves for up to seven years, Great Lakes is currently installing a 1200 t/h capacity crushing plant. The mountain will be levelled to ground level at 55 m. Access roads to the top of the ‘peak’ are too steep for haul trucks. The contractors will therefore remove the top 20 m to allow easier gradient access — initially pushing blasted rock down the slope to a stockpile at the foot of the mountain. During this ‘levelling’ operation, the Tamrock drill rig is drilling just 10 m deep holes on a 3.25 m by 3.5 m pattern. Once the top has been levelled, the contractor will implement the 15 m design bench height. The first blast provided just 80 000 m³ of rock with the second expected to produce 130 000 m³. By completion, the quarry is expected to have provided eight benches. The last five of Tamrock’s 700-2 rigs to be delivered to Technical Drilling and Blasting Co. also feature the new HL800 hammer to provide a slightly increased power output compared with the previous HL700. The hydraulic damping system will also ensure further increased shank, rod and bit life. All the latest rigs include soundproofed and air conditioned cabs which, according to Ross, are essential features when the rigs are working up to 22 hours daily in a region which experiences temperatures that are often above 40°C. “Working approximately 20 quarries it is necessary to constantly move the rigs from one job to another,” he says, adding, “We work the rigs hard. One of the 700-2’s that was delivered in December had clocked up almost 700 hours within its first month.” On average, up to 100 holes/blast are generally drilled by the Tamrock rig at an incline of 5 - 10°, depending on the rock, and in patterns to depths of between 15 and 20 m. Sandvik T51 Retrac drill bits with spherical buttons are fitted to the rigs to produce 89 mm diameter holes. Drilling times are determined by the quarry and type of rock. At the nearby Gulf Quarry, for example, holes can take 20 to 60 minutes to drill. Drilling at the Fujeirah Building Industries quarry can take up to two hours for each hole. During drilling operations, Technical Drilling is achieving between 60 and 600 drill metres life out of each Sandvik T51 drill bit, depending on the density and silica content of the gabbro rock. “The last 18 months have really ‘ramped up’ in an already booming economy to meet local demand for our quality aggregates. As we have grown, so we have turned to Dynatrade to supply even more Tamrock drill rigs,” says Ross. ||**||

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