Boral has implemented an innovative in-pit crushing solution at its new Peppertree Quarry in Marulan South, in the NSW Southern Tablelands, around 180 kilometers southwest of Sydney. 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 tons of aggregate products per annum.
The 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 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 optimize 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.”
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 Metso’s Lokotrack® LT160 together with the company’s patented Lokolink mobile conveyor system.
Intensive design consultation process
Weighing in at an amazing 285 tons and measuring 12 meters high by 25 meters 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 finalization 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 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 customize 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.
As a result of the design consultation process, the LT160 at Peppertree has a number of features that make the machine unique 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 unique requirements that arose during the design consultation phase. These solutions include 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, as well as walkways that extend the full length of the Lokolink conveyors on both sides.
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 re-work and retrofits along with the associated loss of production.
Anatomy of a 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-put 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 one meter in size. In this way, energy isn’t 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 1150 tons 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 operator’s 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 around 70 meters 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 it’s 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 perfect template for a project”
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 mid-August 2013.
“We believe that the outcome of the design process will result in overall lower costs of operation,” Boral’s Sydney Aggregates Project Executive Manager David Bolton says.
“One of Boral’s key lessons from this project is that when importing a 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.”
*Metso Outotec was formed July 1, 2020 when Metso and Outotec merged into one company. This case study has been written prior to the merger under the old company name.