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Sandvik reliability helps Emirate’s gabbro-quarrying success

THE Emirate of Fujairah continues to be the region’s ‘bread basket’ for construction projects in Dubai and Abu Dhabi. And, with many neighbouring Gulf countries banning quarry operations, its gabbro-based aggregates and rock armour for breakwaters are equally in high demand.

Demand for gabbro remains strong as it is recognised as one of the world’s hardest rocks, with a typical density in excess of 3t/m3, a crushing factor of 10 and a 61% silica content.

Each day a continuous team of trucks make the journey from the dozens of quarries in the Hajjar Mountains to the projects across the UAE.

Despite the global economic slowdown, demand continues to be felt at the front end of the ‘aggregate food chain’ where the requirement for drilling and blasting activities remains high.

With blasting strictly regulated across the Emirate, five companies specialise in drill and blast contracting in varying degrees for the quarrying sector.

Technical Drilling and Blasting specialises almost exclusively in quarry activities and handles contracts for about 24 quarries in Fujairah.

The company’s technical manager, Bill Armstrong confirmed that Technical Drilling and Blasting has a fleet of 16 surface top-hammer drills and two down-the-hole drill rigs including nine Sandvik rigs.

According to project manager Alok Ojha, the key to much of the company’s success has been the operational life and productivity of its Sandvik rock tools, all ordered through local distributor Dynatrade.

“Initially we used rock tools from the respective rig manufacturer but trials soon found that the Sandvik rock bits and rods were providing 100% longer operational life,” he said. “For example, we were using 60 rods which were continually snapping compared with 30 Sandvik rods in the same conditions.”

And, for the drill bits, the life expectancy was even greater, as much as three times with Sandvik Retrac bits.

According to Mr Armstrong, generally in hard-rock conditions 700-800m/bit was achieved and up to 2,000m/bit in softer conditions.

Technical Blasting and Drilling carry out on-site regrinding after the first 400m with a second regrind after another 200m.

Each blast site is thoroughly surveyed with extensive details of each drill-hole recorded. Blasts are planned weeks in advance and the explosives ordered. UAE police and security witness all blasting operations and carefully monitor the explosives used. The growth in demand over recent years put extra strain on the police forces resources and Technical Drilling and Blasting has been negotiating with the local authorities that a change in restrictions would help.

Until recently, only two blasts at a maximum of 3t/d on a single site could be undertaken. Technical Drilling and Blasting was able to demonstrate that a single blast of 10t made everyone’s life easier and allowed the police and other authorities to visit more sites without taking any extra time.

Today, Mr Armstrong is actively trying to increase the 10t limit to streamline the process even further.

In a typical quarry development, Technical Blasting and Drilling use a combination of the Sandvik rig and tools to supply around 65,000m3/mth. “It should be more but many of the quarry managements are poor at planning,” said Mr Armstrong, adding that in better months up to 80,000m3 is supplied. This is achieved working a 10-hour shift over six working days with 4in holes in hard rock.

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