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Crushing, Screens & Feeders, Conveying, Plant & Equipment, Mobile Plant

Articles from CRUSHERS PLANT & EQUIPMENT (735 Articles), SCREENING PLANT & EQUIPMENT (667 Articles), MOBILE CRUSHERS (506 Articles)

Boral’s Lokotrack LT160 at its Peppertree Quarry is the largest, most sophisticated mobile crusher in the southern hemisphere.
Boral’s Lokotrack LT160 at its Peppertree Quarry is the largest, most sophisticated mobile crusher in the southern hemisphere.
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Design collaboration leads to in-pit solution at Peppertree

Demands for greater efficiencies, as well as higher standards of safety and sustainability, are driving a move towards in-pit crushing. Following an extensive design consultation process for its Peppertree Quarry, Australia’s largest building and construction materials supplier Boral is leading the way in world’s best practice for in-pit crushing.

Boral has implemented an innovative in-pit crushing solution at its new Peppertree Quarry, at Marulan South in the New South Wales Southern Tablelands, about 180km southwest of Sydney.

Due to become fully operational in 2014, the new quarry will supply the Sydney metropolitan area and greater NSW building and construction industries with up to 3.5 million tonnes of aggregate products per annum.

The Peppertree Quarry 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. Peppertree will ensure Boral maintains its competitive position as a leading supplier of quarry products for many years.

Sydney Aggregates Project executive manager David Bolton explained the significance of the new development: “We have over 80 million tonnes of proved resource at Peppertree and over 1.8 billion tonnes of inferred resource on land owned by Boral in the Peppertree area. This puts us in a great position for sustainable long term supply of high quality construction materials into Sydney and the surrounding areas.”

In addition to the Peppertree Quarry, the $200 million Sydney Aggregates Project includes new rail infrastructure in and around the quarry, a new manufactured sand plant at Boral Cement in South Marulan and a new rail transfer terminal at the Boral Maldon Cement Works, near Picton, NSW.

BENEFITS OF MOBILE IN-PIT CRUSHING
Construction of the new facilities at Peppertree started in July 2011 after more than a decade of planning. A risk assessment of the crushing process led to the selection of in-pit crushing as the safest and most efficient option for the new plant. Boral site manager Steve Parsons said the use of in-pit crushing for quarry applications has been a trend in Europe for some time but is relatively new in Australia.

“Boral is now looking to optimise its quarrying process and get away from the traditional load and haul methodology where you have a large number of trucks and people moving between the blast site and the fixed crushing plant,” he said.

The mobile crushing solution implemented at Peppertree has allowed Boral to significantly reduce its mobile fleet, with associated fuel consumption, safety risks and maintenance requirements.

Boral Sydney Aggregates Project’s senior OHS adviser Natalie Constantine said the mobile crushing solution suits Boral on a number of fronts. “One is the safety aspect. It reduces our mobile fleet so we have less traffic movements on the site, which is much safer,” she said.

“From an environmental perspective, it reduces fuel consumption and the environmental impact of dust emissions. From a health and safety as well as an environmental perspective, it’s a really great solution but most importantly from an operational perspective it does everything we need it to do.”

Rigorous research into a crusher that could handle the planned production volume at the Peppertree plant led Boral to select Metso’s Lokotrack LT160, together with the company’s patented Lokolink mobile conveyor system.

A Hitachi 1200 excavator loads directly to the Lokotrack LT160 crusher.
A Hitachi 1200 excavator loads directly to the Lokotrack LT160 crusher.
Boral’s Lokolink conveyors have walkways that extend along their entire length on both sides.
Boral’s Lokolink conveyors have walkways that extend along their entire length on both sides.
Lokolink conveyors take the crushed rock to the belt conveyor, which in turn takes it to the secondary crushing process.
Lokolink conveyors take the crushed rock to the belt conveyor, which in turn takes it to the secondary crushing process.
INTENSIVE DESIGN CONSULTATION PROCESS
Weighing in at 285 tonnes and measuring 12m high by 25m in length, the Lokotrack LT160 at Peppertree is the largest mobile crusher in the southern hemisphere. Extensive design consultation between Boral’s technical staff and Metso’s design team prior to design finalisation and manufacture has produced an extremely sophisticated machine, with a number of innovations not seen on a mobile plant before.

From the outset, Boral was determined to ensure its new facilities incorporated world’s best practice in safety, sustainability and efficiency.

One of the major challenges was to customise the LT160 to meet Boral’s strict safety requirements, which are even more stringent than Australian and European standards. To achieve this, Boral put together a team of designers, engineers, operators and OHS personnel to review the LT160 design and to identify any potential hazards and improvements before accepting the final design.

This was a new approach for Boral. “We generally buy off the shelf plant and subsequently modify it on-site,” Boral project manager Kai Kane said. “We spent a number of days with Metso’s designers in the UK, then another two or three days with the designers in Finland to get the process under way. After that, there were a number of video conferences that delivered the machine that we have today.”

Regular video conferencing between the Boral and Metso teams was carried out over six months and allowed various improvements to be made, with about 50 safety related and general design changes. 3D models were used to conduct a virtual “walk through” of the plant. Risk assessments were carried out at each design stage. As part of the selection and design process, the Boral team also reviewed an LT160 that has been operating at Swindon in the UK for 10 years.

As well as ensuring that the crusher conformed to Boral’s stringent safety requirements and was easy to operate and maintain, minimising noise was also an important outcome.

“At Peppertree we have to meet certain noise criteria,” Boral’s environmental adviser Sharon Makin said. “We modelled the noise impact using real time data from a similar operating crusher to make sure that the new machine and its controls would work for us.”

DESIGN SOLUTIONS
As a result of the design consultation process, the LT160 at Peppertree has a number of features that make the machine unique in relation to current safety practices.

Some of these features, such as guards and using stairs rather than ladders for maintenance access, are Australian standards requirements, whereas others are unique requirements that arose during the design consultation phase including:
  • Shrouds around the crusher to reduce both dust and noise.
  • Rubber wear liners on the hopper to reduce noise.
  • A service crane installed for jaw liner changes to eliminate the need for a mobile crane.
  • Walkways that extend the full length of the Lokolink conveyors on both sides (rather than one side).

Some of the solutions are extremely simple but very effective. For example, the exterior lights on the crusher have magnetic mounts so operators can move them around to ensure the best lighting of their work areas at night.

“Another thing that’s really interesting is the segregation of the electrical switch room,” Constantine said. “It appears to be all one structure but when you put the crusher in situ the electrical switch room has its own legs that jack up to slightly separate it from the rest of the structure, so it isn’t affected by vibration when the equipment is operating.

“That’s a very neat solution and will reduce maintenance resulting from wear and tear on that part of the building. It’s another one of those really clever solutions that Metso put in place.”

By fully meeting Australian standards and Boral’s requirements before delivery, Metso spared Boral significant costs and avoided the need for site rework and retrofits, along with associated loss of production.

ANATOMY OF A TRUCKLESS SYSTEM
In a conventional crushing plant, a drill and blast team blast the shot and develop a muck pile. A front end loader at the muck pile loads haul trucks which transport the rock to a fixed primary crusher.  With the in-pit crushing solution at Peppertree, an excavator located on the muck pile loads material directly into the Lokotrack’s hopper.

The rock moves along a grizzly feeder that passes undersized rock directly onto the machine’s outbound conveyor. Only the large rock that needs to be crushed passes through the jaw crusher, which is capable of processing rocks up to one metre in size. In this way, energy is not wasted on passing small material through the crusher.

Crushed rock is then transported to the fixed, in-pit belt conveyor via two mobile Lokolink conveyors. The fixed conveyor carries crushed rock from the Lokotrack to the fixed plant for further processing. A patented swivel mechanism on the Lokolinks ensures crushed material flows freely at all conveyor angles.

The Lokotrack LT160 can crush 1150 tonnes of rock per hour and needs to be relocated every few hours – a process that can be done in minutes by an operator via a remote console worn around the waist. The Lokotrack is moved to the next loading position and the unique technology of the Lokolink conveyors allows them to simply follow.

When blasting is performed, the Lokotrack and Lokolink conveyors move to a safe distance about 70m away. After the blast, a wheel loader cleans the quarry floor and the Lokotrack moves to the new muck pile. Operation resumes with minimal production downtime.

When the time comes to move to a different pit location, the Lokolink conveyors are disconnected from the field hopper using hydraulic actuators. The Lokotrack and Lokolinks can also move from one level to another along a normal ramp.

The LT160 is a fully self-contained electrical machine. Its track-mounted drive is hydraulic while the grizzly feeder and the 200kW crusher motor are driven electrically, so there is no environmental impact from diesel fumes.

However, in case electrical power is unavailable the machine has a reliable, on-board Caterpillar diesel generator that can be used to run the Lokotrack’s hydraulic system and Lokolink conveyors.

SYSTEM AUTOMATION AND CONTROL
The Lokotrack’s start-up and crushing process is automated by a Metso IC900 ?PLC-based system designed to protect, control and operate the machine. ?Hydraulic oil pressure and temperature sensors as well as conveyor and feeder speed sensors are located around the machine and wired to decentralised input/output modules that are connected back to the IC900 system via CAN bus (or controller area network).

Critical machine parameters provided by the sensors can be monitored at the user interface, which is also connected to the control system via CAN bus. If any of the process parameters, such as pressure or temperature, move beyond their range limit, a warning or alarm is given at the display.

The IC900 is connected via the Metso gateway to Boral’s distributed control system and SCADA system, so all operations can be monitored remotely. The Modbus-based gateway interface on the LT160 is connected wirelessly to an ethernet port on the field hopper and then cabled to the site’s control room.

Feed rate control to the crusher is a crucial parameter for process optimisation. Operating in automatic mode, the IC900 system can make adjustments to the feed rate or, if necessary, stop the feed altogether. As well as showing on the IC900’s display, process parameters are sent wirelessly to a human-machine interface panel located in the operator’s cabin of the Hitachi EX1200 excavator.

Cameras on the LT160 show the excavator’s operator what is happening within the feed process on the Lokotrack. If necessary, the operator can take over to finetune the feed rate via the human-machine interface panel in his cabin.

A belt weigher incorporated in the first Lokolink continuously monitors product output, which is displayed by the IC900 display on the LT160. A separate, specific belt weigher display is located in the excavator next to the human-machine interface panel.

The automation system controls the entire crusher start-up process. The operator only has to start the LT160 then press the process start-up button and the IC900 sequentially starts the entire system, beginning upstream with the field hopper pan feeder, the Lokolink conveyors, additional devices (water spray system), the Lokotrack’s main conveyor, the crusher, the grizzly feeder and then the LT160 pan feeder.

PERFECT TEMPLATE

After the machine was delivered to the Peppertree site in late 2012, the LT160 went through a three-stage commissioning process (static, dry and wet) and achieved practical completion in the middle of August this year. “We believe that the outcome of the design process will result in overall lower costs of operation,” Bolton said.

“One of the key lessons for Boral from this project is that when importing plant and equipment there are a number of opportunities to adjust the design and capability of the equipment. These opportunities are rarely taken up by Australian industry. We’ve found that the need to partner with offshore suppliers is critical – and it’s achievable.”

While there were challenges with adapting the LT160 to Boral’s rigorous standards, Parsons said the project ran extremely well due to Metso’s commitment, as well as the trust and rapport between the Metso and Boral teams.

“The whole thing worked very well. It was the understanding of what was required and the ability of both teams to communicate seamlessly that delivered the result. It’s the perfect template ?for a project.” •?

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Source: Metso










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