Gulf Construction Online - Trommels rock in Qatar port project

Drilling & Quarrying

Both machines operating in line.

Trommels rock in Qatar port project

01 October 2008

Two heavy-duty Hercules Trommels, manufactured by Stelex Construction Equipment of the UK, are currently operating on a major port extension project in Qatar.

The construction project, one of the largest in Qatar, is a joint venture operation between Qatar Quarries and Boskalis Dredging for the building of the Ras Laffan port extension on the country’s northeastern coast.
Both Trommels – Model HT232s – have a barrel diameter of 2.3 m and are capable of through putting as-dug rock at a rate of 1,000 tonnes per hour. “Working 24 hours per day, seven days a week, the machines are supplying clean graded rock for the building of a deep-water harbour and breakwater. The two machines are the largest Hercules Trommels operating outside of the UK,” says a spokesman for Stelex.
Rock blasted and dug from the quarry face is fed to the Trommels, which are positioned side-by-side at the rock face, by a fleet of dump trucks.
The feed hopper, which can accommodate 160 tonnes, is made of Hardox steel to provide high wear resistance. A variable speed reciprocating plate feed table, which is supported on rollers beneath the hopper, moves material into the barrel via hydraulic rams that can be adjusted to the required tonnage.
Elaborating on the features of the equipment, he says: “The 2.3-m-diameter barrel (made up of two 4-m-long segments) is manufactured from high-grade steel bars welded to form segments that are bolted together. The apertures were made to suit this customer’s individual requirement. The barrel is supported on four steel rollers, two of which are driven by heavy-duty, variable speed hydraulic motors (no drive chain or sprockets to maintain). The speed of the barrel, which is variable, can be set to suit the type of material that is being fed to ensure optimum cleaning and grading at all times.
“Drive for both the feeder and barrel is provided from a separate, remotely stationed electric/hydraulic power pack. As part of the contract, the machines were specified to operate in temperatures of up to 50 deg C.”
The cleaned limestone rock is loaded direct from the Trommels into large road transport vehicles for delivery to the construction site storage yards.
All the equipment was designed, built and commissioned within the scheduled timeframe and put to work on site by Stelex engineers. When the project is completed, the Hercules Trommels will have processed more than 30 million tonnes of rock for the construction of this new breakwater, which will provide additional deep water port facilities for the increasing shipping traffic through this important seaway, including large LNG container vessels bound for the UK.
In recent weeks, Stelex has been busy installing its latest rental mobile Trommels in several large quarries in the UK and Europe, as quarry operators are recognising the potential value of their hidden reserves. These machines are carrying out recovery trials on overburden and difficult materials which would normally be tipped as waste. These operating trials have shown that recovery rates of up to 90 per cent can be achieved.