Gulf Construction Online - Tamrock aims for peak efficiency

Quarrying

Tamrock’s drills at work on the mountain peak in Fujairah.

Tamrock aims for peak efficiency

Tamrock rock drills are currently ensuring high output for a UAE drilling contractor working on a new quarry in the mountains of Fujairah.

01 June 2005

UAE specialist drill and blast contractor Technical Drilling and Blasting Company (TDBC) – which has recently taken delivery of its fifth Tamrock 700-2 surface drill rig in less than three months – has already put the new rig to immediate use in a new mountain-top quarry in Fujairah.

The rig – fitted with Sandvik rock drilling tools – has started work on Doha quarry on a 201 m-high peak in the foothills of the Hajar Mountains.
Work on the Doha quarry, developed by the 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 the quarry's reserves expected to last up to seven years, Great Lakes is currently installing a 1,200 tonne- -per-hour (tph) capacity crushing plant. Access roads to the top of the “peak” are too steep for haul trucks. The contractors will, therefore, remove the top 20 m to provide an 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 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 cu m of rock with the second expected to produce 130,000 cu m. By completion, the quarry is expected to have provided eight benches.
TDBC specialises in drill and blast contracts for a number of major quarries throughout Fujairah and also undertakes some civil engineering projects including pipelines across the region.
It is the quarries, however, which provide the toughest 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 rock, high-density gabbro – in excess of 3 tonnes per cu m 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 61per cent silica content.
Since its inception in 1998, TDBC has been using two Tamrock CHA660 surface rigs with great success. According to deputy manager, Tom Ross, each has provided more than 13,000 hours of operation.
Having secured additional contracts with new quarries, TDBC recognised the need for a new rig, opting for the slightly larger production model, the Ranger 700-2. Since then, with the boom in construction, the contractor has placed orders for a further eight rigs with local distributor Dynatrade, – the last five having been delivered over the past three months. The latest orders brings TDBC's total Tamrock fleet to 11 rigs in just five years.
“Over recent years, we have seen a change in market demands,” says Ross. “There is today a trend 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 per cent of holes drilled today are 89 mm diameter, whereas in the past, hole diameters were generally 64 mm and 76 mm.
“We have found that the new rig provides us with increased production and a high degree of accuracy,” Ross continues. “Drilling larger-diameter holes with thicker rods, also from Sandvik, means less breakages.”
The Tamrock 700-2 with its European spec is proving the ideal rig, particularly when fitted with Sandvik 89 mm flat face retrac bits, says a spokesman for Sandvik.

Range 700-2 rig
Elaborating on the Range 700-2 rig, the spokesman says: “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 cabletightness automatics, ensures maximum operator safety.
“A turntable-mounted articulated boom and rock-drilling assembly offers 120-degree arc movements and a massive 17.6 sq m drilling area coverage from one setup.
The 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 to 80 dB(A), provide the operator with an excellent working environment.
“A single multi-function joystick proportionally controls drilling rationale and a number of standard operations are automatically implemented, allowing the operator to focus on the work in hand.”
The last five Tamrock 700-2 rigs delivered to TDBC 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 with the rigs working up to 22 hours daily in a region which experiences temperatures above 40 deg C.
“Working in approximately 20 quarries, it is necessary to constantly move the rigs from one job to another,' he says. 'We work the rigs hard. One of the 700-2s delivered in December had clocked almost 700 hours within its first month.”

Sandvik rock tools
On average, up to 100 holes/blast are generally drilled by the Tamrock rig at an incline of 5 to 10 degrees 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.
“We have considerably boosted output over the past 18 months in a 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.