International building and construction materials group, Boral, says it is now leading the way in global best practices for in-pit crushing. The group is headquartered in Sydney, Australia, a country whose quarry industry’s demands for greater efficiencies as well as higher standards of safety and sustainability are driving a shift towards in-pit crushing.
Following an extensive design consultation process for its Peppertree Quarry, Australia’s largest building and construction materials supplier has implemented an innovative in-pit crushing solution at the quarry in Marulan South in the New South Wales (NSW) Southern Tablelands, around 180km south-west of Sydney, writes Sylvia Aitken.
The new quarry, due to become fully operational in 2014, will supply the Sydney metropolitan area and greater NSW building and construction industries with up to 3.5 million tonnes of aggregate products/year.
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 that Boral maintains its competitive position as a leading supplier of quarry products for many years to come.
“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,” says Sydney Aggregates project executive manager David Bolton.
In addition to the Peppertree Quarry, the AUD 200 million (€135.4 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, after 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 says that 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 operations, where you have a large number of trucks and people moving between the blast site and the fixed crushing plant,” he says.
All the fixed crushers and screens in the primary, secondary and tertiary sections of the plant were suppied by
The mobile crushing solution implemented at Peppertree has allowed Boral to significantly reduce its mobile fleet with its associated fuel consumption, safety risks and maintenance requirements.
Boral Sydney Aggregates Project’s senior OHS adviser Natalie Constantine says the mobile crushing solution suits Boral on a number of fronts.
“One is the safety aspect: it reduces our mobile fleet, so we’ve got less traffic movement on the site, which is much safer,” she explains.
“From an environmental perspective, it reduces fuel consumption and the environmental impact of dust emissions. From a health, safety and 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 finding a crusher that could handle the planned production volume at the Peppertree plant led Boral to select
Extensive design consultation between Boral’s technical staff and Metso’s design team prior to design finalisation and manufacture has produced “the most sophisticated machine of its kind, with a number of innovations never before seen on a mobile machine.”
From the outset, Boral says it was determined to ensure its new facilities incorporated the world’s best standards 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 an off-the-shelf plant and subsequently modify it on site,” explains Boral project manager Kai Kane.
“We spent a number of days with Metso’s designers in the UK and then another two or three days with the designers in Finland to get the process underway. Subsequent to that, there were a number of video conferences that delivered the machine that we have today.”
After a more than six-month period of exchanging views, there were about 50 safety-related and general changes made to the machine’s previous design. 3D models were used to conduct a virtual walk-through of the plant. Risk assessments were carried out at each design stage.The Boral team also reviewed an LT160 that had been operating at Swindon in the UK for around ten years.
In addition to 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,” says Boral’s environmental adviser Sharon Makin.
“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.”
Effective design solutions
As a result of the design consultation process, the LT160 at Peppertree has a number of features that make the machine different with regard to current safety practices.
Some of the solutions, such as guarding and using stairs rather than ladders for maintenance access, are requirements of Australian standards whereas others are requirements that arose during the design consultation phase. These solutions include shrouds around the crusher to reduce 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, as well as walkways that extend the full length of the Lokolink conveyors on both sides.
Some of the solutions are said to be 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,” says Natalie Constantine.
“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 is not 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.”
Ensuring that the machine fully met Australian standards and Boral’s requirements before delivery brought the company significant cost savings by eliminating the need for site rework and retrofits along with the associated loss of production.
Truckless system
In a conventional crushing plant, a drill and blast team blasts the shot and develops a muck pile. A front-end loader at the muck pile loads haul trucks that 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 crusher’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 1m 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 Lokolink conveyors ensures crushed material flows freely at all conveyor angles.
The Lokotrack LT160 can crush 1,150tonnes of rock/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 operator’s waist.
The Lokotrack is moved to the next loading position and the technology of the Lokolink conveyors allows them to simply follow.
When blasting is performed, the Lokotrack and Lokolink conveyors move to a safe distance around 70m away. After the blast, a
When it is time to move to a different pit location, the Lokolink conveyors are disconnected from the field hopper using hydraulic actuators. The Lokotrack and Lokolink conveyors can also move from one level to another along a normal ramp. The LT160 is a fully self-contained electrical machine. The track-mounted drive of the machine is hydraulic, while the grizzly feeder and the 200kW crusher motor are driven electrically so there is no environmental impact from diesel fumes. However, if electrical power is unavailable, the machine has a reliable, onboard CAT diesel generator that can be used to run the Lokotrack crusher’s hydraulic system and Lokolink conveyors.
After the machine was delivered to the Peppertree site in late 2012, it went through a three-stage commissioning process (static, dry and wet) and achieved practical completion in mid-August 2013.
“We believe that the outcome of the design process will result in overall lower costs of operation,” says David Bolton. “One of Boral’s key lessons from this project is that when importing a plant and equipment there is 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 in adapting the LT160 to Boral’s rigorous standards, Steve Parsons says the project ran extremely well due to Metso’s commitment and the rapport between the Metso and Boral teams.
“All in all, everything 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.”Remotely monitored operation
The Lokotrack crusher’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 I/O modules that are connected back to the IC900 system via a CAN bus. Critical machine parameters provided by the sensors can be monitored at the user interface, which is also connected to the control system via a 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 (DCS) and SCADA system so that all operation 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. In addition to 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
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 fine-tune 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, 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 such as the water spray system, the Lokotrack crusher’s main conveyor, the crusher, the grizzly feeder and the LT160 pan feeder.
CRAWLER EXCAVATORS
1 x Hitachi EX1200 crawler excavatorWHEELED LOADERS
1 x Caterpillar 980HAULING
2 x Metso Lokolink mobile conveyorsMOBILE CRUSHERS
1 x Metso Lokotrack LT160 mobile jaw crusherFIXED CRUSHERSAND SCREENS
Sandvik primary, secondary and tertiary crushers/screens
