As you approach Boral’s Peppertree Quarry, a two-hour drive from Sydney, it’s immediately obvious this is no ordinary quarry operation.
There are no stockpiles of different products, no loaders and dump trucks moving material around, no lines of tip trucks collecting material for delivery to building and construction sites back in Sydney – and very little noise.
Instead, eight gleaming stainless steel towers soar into the sky – storage silos for the base materials that combine to make up the numerous different product mixes the site can produce.
These silos are fed by a complex 3D maze of conveyors from the multiple crushing and screening plants housed in an array of structures – which in turn are fed from a single, massive stockpile bringing in the raw crushed material from the quarry pit itself.
The quarry’s entire output leaves the site by train – four trainloads a day, every day – with multiple product mixes in every trainload. Not a single kilogram of product leaves the site by road.
And yet a single person can control this entire processing operation.
The whole site has just 30 people running it across a 24/7 operation; compare this with equivalent output conventional quarry operations, which typically require more personnel than that, along with multiple items of mobile equipment.
So what was behind Boral’s decision to go far beyond anything that had been done in Australia previously and build a world’s best practice operation?
A unique combination of history, geography, geology and environment – along with some equally unique challenges – has resulted in the company’s new Peppertree processing plant.
David Bolton, Boral Construction Materials’ general manager of quarries for New South Wales and the Australian Capital Territory, said for many years the company had known it would need to replace its Penrith Lakes Scheme quarry, on the western outskirts of Sydney.
“Penrith Lakes supplied Sydney with construction materials for over 100 years but was exhausted by 2015,” he said.
Quarrying at Penrith Lakes officially ceased in July 2016 after almost 130 years of extraction.
Boral needed a replacement quarry close enough to Sydney to economically transport product to the metropolitan region and to the demanding standards of its customers – from homeowners, small tradespeople and builders to multinational civil and building contractors and their clients.
“We identified a large deposit of granodiorite adjacent to our existing limestone quarry near Marulan, south of Sydney,” Bolton said.
Granodiorite is a very hard and durable rock, making it ideal for concrete and asphalt applications.
“Our Peppertree Quarry is a generational investment, and will secure Boral and the Sydney construction materials market for many, many years to come,” Bolton said.
“We were granted consent to extract and process 3.5 million tonnes a year. This consent is for an initial period of 30 years, but the resource at Peppertree will last significantly longer than that.”
One issue Boral faced in the move from Penrith Lakes to Peppertree was the fact the new site had no sand resources.
Accordingly, the company decided to develop its own manufactured sand products, combining granodiorite from the new Peppertree Quarry mixed with product from its adjacent limestone quarry.
In fact, 40 per cent of the output from Peppertree is manufactured sand – and it has proven to be a product of such outstanding characteristics that demand for it is growing.
Transport by rail
Bolton said another major challenge for Boral was getting its product to Australia’s largest city, almost 200km away. The quarry’s target output would have meant a steady stream of trucks travelling up and down the Hume Highway, and into an already very congested city road network.
“The need to ensure that all aggregates were railed from the site rather than truck presented a number of challenges to Boral and to Sandvik in developing the systems and infrastructure to accommodate such large volumes of diverse products by rail,” he said. “The rail loading infrastructure that was developed by Boral and Sandvik for this project, I believe, is one of a kind in this industry.
“It combines the ability to load multiple products, doing this at high capacity, similar to large scale mining operations.
“However, in large scale mining operations you are dealing with just a single product that’s going onto a train, whereas the system we have developed in conjunction with Sandvik allows us to deal with multiple products at very high rates, thus maximising our rail utilisation.”
To maximise the plant’s efficiency and productivity, minimise ongoing operating costs and ensure a high degree of flexibility to meet changing market demands well into the future, Boral adapted the principles of “lean manufacturing” at its Peppertree operations.
“The entire design of Peppertree incorporates a number of lean manufacturing initiatives to reduce material transport requirements and material movements, as well as excess stocks of materials on-site,” Bolton said. “Products from Peppertree and the way that these products were delivered to our markets drove us to design a plant based on what our customers truly valued.“From these customer requirements, the original project specification was developed, and Sandvik and Boral then designed and built the plant and equipment to meet those needs.”
Fully integrated plant
From the earliest specification and design stage, Boral worked closely with Sandvik Construction to develop a fully integrated processing plant that met the highest standards of production reliability, product quality and safety.
Once the raw quarried material leaves the pit, Sandvik-supplied conveyors, crushers, screens, air classifiers and surge bins, along with sophisticated control and quality monitoring systems, manage every aspect of production until the final product is loaded onto the train.
A key element of this process has been to ensure products out of Peppertree meet specifications, and achieve market acceptance.
According to Peppertree Quarry manager Angus Shedden, the quality of Peppertree products has exceeded all expectations.
“The feedback from our customers has been exceptional, far better than we expected,” he said. “Our secondary crushers, the Sandvik cone crushers, are really delivering fantastic shape.”
Shedden said this shape straight off the cone crushers was of such high quality the operation had been able to reduce the feed going through its quaternary vertical shaft impactor (VSI) crushers.
“We are also getting excellent consistency of our aggregate,” he said. “We are able to produce the same product consistently, first time, all the time. The biggest success here, from my point of view, has been the quality of the aggregates. The quality has just been exceptional.
“Since production out of Peppertree started, we have supplied a number of high profile infrastructure projects in Sydney – including Barangaroo – with customers very happy with the high quality aggregates that we are producing.”
Shedden is proud of the high degree of automation at Peppertree, and the benefits it has in terms of safety and efficiency.
“Because of the automation in the plant, not only can we operate the plant with one person, but it also means that we don’t have lots of vehicles, and we don’t have huge numbers of people on site,” he said.
“Our standard operating team per production shift is four people – and I defy anywhere else to have those sorts of numbers to produce the output we are achieving.
“For us, from an occupational health and safety (OHS) point of view, that has huge implications. A lot fewer people around and a lot fewer vehicles takes away a huge amount of risk. And, from an operational cost, we don’t have all that maintenance to carry out on mobile plant and equipment.
“As well, not having a lot of vehicles moving around the site really helps with our environmental controls.”
Boral has taken the opportunity in developing a greenfield operation to introduce highly innovative environmental and OHS solutions, as Sharon Makin, stakeholder and environmental manager at Peppertree, explained.
“I had the privilege of actually starting here back when work on the site began in July 2011, and have stayed on to do health, safety and environment through operations,” Makin said.
An important element of the Peppertree site from the start was the “safety and design” concept.
“What that has meant in terms of operation is an OHS management system which ties in with all the physical, mechanical safeguards that we have put in place here,” Makin said.
“Some examples of what came out of this safety and design process is that everything is guarded – and all guarding is bright yellow in colour, so you can pick when something might be missing.
“There are no underground conveyors or underground tunnels; everything is above ground. Access is down the side of each conveyor and confined spaces, as much as possible, have been removed. Ladders have been almost eliminated from the operation, and wherever we can, access is by stairs.”
From an environmental point of view, Makin described the plant as “a dry process”.
“The site doesn’t have a water supply – apart from what falls out of the sky – so Boral and Sandvik also looked at what we needed to do in regard to environmental performance,” she said.
“So, for example, all conveyors are covered, all operations are within buildings, and we have minimal water usage to control dust.”
Because of the restricted water supply at Peppertree, Boral and Sandvik worked closely from the earliest stages of the design process to eliminate all haul trucks from the operation.
“Material comes out of the pit by conveyor, it goes through all the processing operations via conveyor,” Makin said.
“We are also the first quarry in Australia to put our product into silos, so we don’t have on-ground stockpiles that need to be watered and, again, we don’t need the trucks to haul them off-site.
“And as Peppertree has 100 per cent of its dispatch by rail, the silos feed the conveyor direct into the wagons, and so we minimise the need for water through that process as well.”
One of the key people in helping Boral develop its vision of a highly automated, extremely safe site with the highest environmental standards has been Kai Kane, the project manager for Boral’s Sydney Aggregates Project, which covers the Peppertree Quarry, its adjacent limestone manufactured sand plant, rail infrastructure and the Maldon rail terminal that services the site.
“The criterion that we used in developing our concepts for Peppertree was extensive benchmarking of leading international sites,” Kane said. “We spent several months benchmarking various sites by Sandvik, in particular Perrier TP’s Mions Quarry in France, which became the reference point for this particular project.
“These reference plans were then used to consolidate our designs and use them for benchmarking to get world’s best practice in our design process, and then develop our safety and design requirements, as well as Australianising all those European designs.
“The safety and design process between the Boral and Sandvik teams was very iterative and collaborative. Our processes included extensive risk assessments, going through each of the existing designs and then through our new design to make sure that we captured the earnings from the ones that we benchmarked.
“The plant we now have is world standard in terms of safety and quality, and has produced an exceptionally ergonomic and maintainable operation.”
Kane highlighted Peppertree’s train loading system and its “reject stockpile” concept as particularly innovative solutions to significant challenges.
“Our train loader, which was a collaboration between Boral and Sandvik, has resulted in a world class rail loading system, which operates at 2000 tonnes per hour,” Kane said. “It is the most efficient loading system that Boral currently operates.
“It is unique in that it is capable of loading multiple products – in our case, multiple different products and recipes – something that is unique in the quarrying industry.”
The site’s reject stockpile system is what Kane calls an “elegant solution” to the challenge of dealing with out-of-spec products coming from the silos to the train loader.
Product comes out of the silos at 2000tph, and before going to the train loader goes through a sampling station, where a high speed camera monitors to ensure the product passing through the stations meets specifications.
“Any out-of-spec materials are picked up within five seconds as they go past the camera detection systems, then the chute changes direction and diverts the material to a radial stacker and our reject stockpile,” Kane said.
“These materials that come out of our radial stacker are then recirculated by a front-end loader, back into our screening and crushing plants for recovery.
“Comparing it with the plants we benchmarked when designing and specifying Peppertree, this is now in a superior state to all of those, particularly from an automation perspective.”
David Bolton said customer acceptance of Boral’s product out of Peppertree, in both concrete and asphalt operations, was even better than the company had hoped. He reiterated the development of Peppertree as “a generational investment” for Boral.
“It’s been a once in a lifetime opportunity to be involved in something of this scale,” he said. “It’s also been a pleasure to work with a great team at Boral Peppertree and a great team at Sandvik.
“What these two teams have been able to achieve working together has really opened our eyes to opportunities for improving our existing operations, as well as learnings we can apply to future greenfield and brownfield developments.”
Source: Sandvik Construction