To meet the infrastructure needs of one of Australia’s burgeoning markets, a Boral operation has turned to multi-action cone crushers to expand and improve its output.
Boral, Australia’s largest building and construction materials supplier, owns about one billion tonnes of quarry reserves strategically located close to its key markets.
A new, state of the art processing plant at the company’s Ormeau quarry will ramp up the site’s production by 400 per cent.
Ormeau is one of the company’s 12 Queensland-based quarries. Centrally located about 30km from the Gold Coast and 40km from Brisbane, the site is within a major rock formation called the Neranleigh-Fernvale beds, a large zone consisting of massive to slightly foliated meta-greywacke with minor bands of shale and argillite. Originally owned by Quarry Industries, extraction at the site began in 1981.
A joint venture was formed in 1987 between BMG Resources and Quarry Industries. This endured until Boral acquired Quarry Industries in 1994. Boral has been the sole owner/operator of the quarry since.
Ormeau is between Brisbane, Australia’s third largest city with a population of about 1.2 million, and Gold Coast, Queensland’s second largest city, which stretches from the outskirts of Brisbane to the northern New South Wales border. Connecting these two cities with modern infrastructure and catering for their rapidly growing populations is driving the need for huge volumes of aggregate.
To help meet this demand, in 2017 Boral embarked on a project to replace Ormeau’s ageing processing plant, quadrupling the quarry’s production capabilities.
Neil Bellamy, Boral’s drill and blast manager for Queensland and the Northern Territory, has been closely involved in the expansion, managing the operational readiness of the project and site interaction.
“The site has traditionally produced around 500,000 tonnes of quarry materials per annum,” Bellamy said. “This included the supply of asphalt aggregate to Boral Asphalt in south-east Queensland, a limited amount of concrete aggregates and manufactured sand to internal concrete customers, as well as other construction materials to the infrastructure and private sectors. Over the next few years we will ramp up production at Ormeau to two million tonnes per annum.”
Limited operating hours
One of Boral’s challenges for the expansion of operations at Ormeau was that the plant is permitted to operate from 7am to 6pm only, Monday to Saturday.
“Because of restrictions to operating hours, and the fact that maintenance must be done within these hours as well, the plant has to have a higher per hour capacity to meet our two million tonnes per annum goal,” Bellamy said. “We also had to allow for ramp up and downtimes, as well as unplanned outages.
In the end, we had to design the new plant to handle 1000 tonnes per hour. This was a challenge, because the engineering of the plant and the equipment within the plant were exponentially more expensive.”
Ormeau’s quarry manager Liam Elsworth said: “When in full production, the new plant will be Boral’s largest quarry operation in Queensland. It will play a key role in supplying various raw materials for Queensland’s burgeoning south-east region, and the state’s growing infrastructure needs.”
In 2017 Boral awarded Metso the contract to design, manufacture and supply an aggregate crushing and screening plant to support the increased throughput. Metso was heavily involved in the entire design process. Boral and Metso staff workshopped the plant’s process flow design and then selected the equipment that would handle the duty.
“Metso has brought a number of innovations to our circuit design,” Bellamy said. “One example was the inclusion of a surge bin post the tertiary crushing station, which allows crusher output material to be metered to the tertiary parallel screening circuit. This results in optimal screening performance, which delivers a very consistent final product. From a particle size distribution perspective, we are achieving some of the lowest standard deviation results within Boral’s quarry network.
“That’s something that I wouldn’t have thought of, but it has been great for our product quality. The standard deviation of product size per sieve is one of the best I’ve ever seen.”
Crushing circuit innovations
The crushing circuit is a three-stage system consisting of a Metso C160 jaw, a GP500S gyratory and three MX4 cone crushers. Metso also supplied the vibrating screens and feeders, conveyors, bins, hoppers and chutes. The plant is highly automated.
“The intent is that the control room will be unmanned, and the automation will see the plant running at capacity throughout each shift without the need for human intervention,” Elsworth said.
The MX4 multi-action cone crushers are the latest design from Metso, automatically optimising the crusher setting and wear compensation in real time, bringing lower operating costs, higher uptime and consistent output.
“We made a business decision to purchase the new MX4 crushers,” Elsworth said. “This is the first installation worldwide where MX4s have been used in parallel as final tertiary crushers. So far, they have met all of our expectations.
“A lot of time and effort went into getting the process control right – it’s more complicated than it looks. For the final product we went with Metso screens.
“The Metso screens with Trellex rubber media are performing well. We’ve done some fine-tuning of the screen apertures and we’ve achieved very good efficiency.”
The upgrade involved completely replacing the old processing plant, which was designed in the 1960s and had been moved to the site from its original location in South Australia.
“Because we built the new plant to today’s standards, it provides greatly improved safety,” Bellamy said. “The design incorporates the latest safety best practices relating to guarding, ingress, egress, etc. The modern automation and control system has a lot of safety functionality built into it.
“For example, there are no risks of overflowing media because the system can perform carefully controlled ramp-ups and shutdowns.”
Not only was the plant designed to improve site safety, it has also been configured for convenient maintenance.
“The plant has been designed with full and easy access to crushers and screens. All the buildings have overhead cranes for maintenance,” Boral’s project manager Kai Kane said. “A minimum number of different types of screens, all using rubber media, were used to reduce our spare parts inventory.”
Energy efficiency is also greatly improved. One criteria for the design of the plant was that the incoming power feed should not need an increase in capacity.
“We didn’t want to upgrade the existing four-megawatt electrical in-feed,” Kane said. “All of the latest technology in the plant has allowed us to achieve that goal while still aiming to increase our plant output to 1000 tonnes per hour.”
Boral had to comply with a range of rigorous environmental requirements to gain approval to expand the quarry, including the commissioning of an environmental plan to minimise impact on the local koala population.
The plan includes maintaining an offset area of forest on land the company owns south of the site.
Boral has also won awards for Ormeau’s storm water management plan; one of the requirements was to ensure the site can deal with a one in 10-year storm event.
“On the southern and eastern side of the site we have the Pimpama River,” Elsworth said. “Previously, the lay of the land meant that a large storm event could cause significant flooding, so we had to raise the elevation of the lower part of the site by about three metres, to make sure it was out of the floodplain. A 60m buffer was also established between the river and the working boundary, which we planted out with more than 40,000 trees.
“We have built a stormwater catchment system with pumping facilities that allow us to pump water back to the pit for our use.”
Other major environmental considerations were the need to minimise waste, noise and dust.
“In relation to waste, there is none”, Kane said. “The new crusher and screening technology means that nothing is wasted. All raw rock input is converted to product.”
The overall plant design also included enclosing the entire crushing and screening process in buildings.
“All the screens and crushers are enclosed for noise control, and there are areas of the plant where we use automated water sprays to control dust,” Bellamy said. “All conveyors are covered, and the screens also have dust encapsulation, even though they are in buildings. The secondary and tertiary crushers also have a foam dosing system, which works well and is automated and adjustable.
“Conveyor belt speeds are slow, so even though the capacity is high, the low velocity doesn’t create a lot of pressure, further minimising dust and noise.”
The new plant with its cutting edge technology has played a pivotal role in the quarry achieving its throughput requirements.
“The assets themselves are performing as we hoped and expected,” Bellamy said. “We have achieved our minimum performance requirements earlier than expected and we were able to quickly ramp up to 90 per cent of capacity.
“We have a very good relationship with the local Metso team. The Metso installation supervisor was very good to work with. He put in long hours to make sure everything was right.”
According to Shaun Fanning, Metso’s Australian vice president for aggregates, the key to delivering this world-class plant was Metso and Boral’s early collaboration to develop the design.
“While we have extensive experience in delivering aggregates plants around the world, Boral was able to bring valuable features into the design based on their operational experience,” he said.
Metso assists customers in the mining, aggregates, recycling and process industries to improve their operational efficiency, reduce risks and increase profitability. Its products range from mining and aggregates processing equipment and systems to industrial valves and controls. Customers are also supported by a broad scope of services and a global network of more than 80 service centres.