Road Transport

Sophisticated quarrying: excavator supports in-pit crushing system

Boral Peppertree Quarry is situated at Marulan South in the NSW Southern Tablelands and is the company’s largest hard rock quarry investment in Australia.
The new quarry will supply the Sydney metropolitan and greater NSW building and construction industries with up to 3.5 million tonnes of aggregate products per annum.

It is home to more than 80 million tonnes of proved resource and more than 1.8 billion tonnes of inferred resource on land owned by Boral in the Peppertree area.

Peppertree is part of Boral’s Sydney Aggregates Project, which will address the anticipated depletion of raw material reserves at the 100-year old Penrith Lakes Scheme in Sydney, of which Boral is a major shareholder.

IN-PIT CRUSHING {{image2-A:R-w:250}}Boral’s innovative in-pit crushing system is developing a reputation as the future of the quarry industry.

The implementation of the Metso Lokotrack LT160 mobile crusher in 2013 reflects the shift towards automation and demand for safer, more efficient and environmentally conscious technology. 

The automation of the crushing process eliminates the need for a large number of haul trucks and personnel moving between the blast site and fixed crushing plant, as is required in traditional load and haul operations.

Boral’s mobile crushing system delivers economic and environmental benefits by significantly reducing its mobile fleet and associated fuel consumption, safety risks and maintenance requirements.

Weighing 285 tonnes and measuring 12m by 25m, the Lokotrack LT160 is the largest mobile crusher in the southern hemisphere.

Customised to meet Boral’s strict safety requirements, extensive research went into the selection and design process of Metso’s Lokotrack LT160 and patented Lokotrack mobile conveyor system.

The Lokotrack LT160 can crush 1150 tonnes of rock per hour and needs to be relocated every few hours — a process that can be completed in minutes by an operator via a remote console worn around the waist.

To optimise its quarrying process, Boral turned to Hitachi for an efficient and reliable solution.

A Hitachi EX1200-6 excavator, renowned for large-scale productivity in quarry applications, is based on the muck pile and loads material directly into the crusher’s hopper.

Process parameters of the Lokotrack LT160, such as hydraulic pressure, temperature and feed rate, are sent wirelessly to an interface panel in the excavator’s cabin.

Cameras positioned on the LT160 allow the operator to observe what is happening within the feed process on the Lokotrack. If necessary, the operator can alter the feed rate via the interface panel in the cabin.

ADVANCED HYDRAULIC SYSTEMS {{image3-A:L-w:250}}The EX1200-6 boasts a new hydraulic system and advanced hydraulic technologies that aim to boost production capabilities and reduce fuel consumption. 

Performance has been improved, including mobility, digging force, swing performance, boom lifting force, operator comfort and visibility.

The excavator is one of Hitachi’s largest earthmoving machines. It has an operating weight up to 114 tonnes, which varies with given weights, with a water-cooled, four-cycle, six-cylinder, in line, turbo-charged direct injection chamber Cummins QSK23-C diesel engine, with gross rated power of 567kW and maximum torque of 3472Nm at 1350 rpm.

Its hydraulic system includes three variable displacement, swash plate-type axial piston pumps, with maximum engine flow of 3×520/Lmin and a pressure setting of 31.9 MPa.

Its swing speed is 5.2 rpm and tramming speed varies from zero to 2.4km/h (low) and 3.5km/h (low). 

The EX1200-6’s weights include a backhoe (comprising 9m boom, 3.6m arm and 5.2m3 bucket), BE-front (equipped with 7.55m BE-boom, 3.4m BE-arm and 6.7m3 bucket) and a loading shovel (with a 6.5m3 heaped bottom dump bucket), with maximum digging reaches of up to 15,010mm, digging depth of up to 9260mm and dumping height of up to 9080mm. The excavator’s front linkage has also been redesigned to enable the front to excavate closer to the machine, for improved combination with dump trucks.

The excavator’s hydraulic features include a boom recirculation system that delivers more pressurised oil to the arm from the pump, to increase arm lowering speed in combined operation of the boom and the arm.

There are two boom modes – comfort and powerful – which can be selected according to job needs. The comfort mode is selected for efficient excavation, while the powerful mode is for productive excavation.

Compared with conventional earthmoving models, with arm positioned vertically and bucket resting on the ground, Hitachi estimates an eight per cent increase in boom lifting force, an eight per cent increase in swing torque and a 14 per cent rise in mobility, with more traction force. An auto lubrication system at the front attachment is provided as standard to simplify daily maintenance, except for the bucket pin and swing circle.

The EX1200-6 also boasts an array of enhanced safety, ergonomic and environmental features and options. These include a high visibility cab with integrated head guard, to protect the operator from falling objects, a large colour LCD monitor with reverse camera, a scheduled maintenance monitor, a pilot control shut-off lever, a step light for night work, wide sidewalks and large handrails, inspection doors and hatches, a variable speed fan for the oil cooler and a condenser for the aluminium radiator, oil cooler and air conditioner.

The radiator and oil cooler are arranged in parallel, to increase cooling efficiency and therefore reduce cleaning time and maintenance. The air condition condenser is easily accessible, especially for cleaning of the oil cooler behind it. Walkways and devices are functionally spaced out for efficient servicing and inspection. The central walkway enables the servicing and maintenance of the engine.

For added maintenance, Hitachi’s MIC mining system logs daily operating conditions and warnings, including engine and hydraulics data. The log is uploaded to the internet and is easily downloadable by PC or PDA. 

Source: Hitachi Construction Machinery Australia

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