A new Metso processing plant at the Boral owned Ormeau quarry will see productivity at the site ramp up by 400 per cent.
With Australian cities spending billions building infrastructure megaprojects, the demand for construction materials is rising.
According to the Queensland Government’s Population growth highlights and trends 2019 report, the state had the third largest population increase in 2017-18, with almost 90 per cent of this occurring in the south-east corner of the state.
The region’s population growth and associated need for infrastructure, is driving the demand for huge volumes of aggregate. Some of the materials to supply this demand are extracted at Boral’s Ormeau quarry, located in the state’s south-east between Brisbane and the Gold Coast.
Situated on top of a major rock formation called the Neranleigh-Fernvale beds, the Ormeau quarry’s resource is made up of massive to slightly foliated meta-greywacke with minor bands of shale and argillite.
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Boral is one of Australia’s largest building materials suppliers and owns around one billion tonnes of quarry reserves. The Ormeau site has been in operation since 1981 and is strategically located close to key markets.
To help meet growing 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 & Blast Manager – Queensland and Northern Territory, has been closely involved in the expansion, managing the operational readiness of the project and site interaction. He says the site has traditionally produced around 500,000 tonnes of quarry materials per year.
“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,” he says.
“Over the next few years we will ramp up production at Ormeau to two million tonnes per annum.”
However, one of the challenges in hitting this new target is a limit on operating hours. The plant is only permitted to operate from 7am to 6pm – Monday to Saturday.
Work, including maintenance, is limited to this window of time, meaning the plant required a much higher per hour capacity to reach the two million tonne target.
“We also had to allow for ramp up and down times, as well as unplanned outages,” Mr Bellamy says.
“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.”
Metso engaged from the beginning
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 throughout the entire design process, workshopping the plant’s process flow design with Boral before selecting equipment.
One innovation incorporated into the design was a surge bin positioned after the tertiary crushing station. This allows the crusher output material to be metered to the tertiary parallel screening circuit, resulting in optimal screening performance and a consistent final product.
“From a particle size distribution perspective, we are achieving some of the lowest standard deviation results within Boral’s quarry network,” Mr Bellamy says.
“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.”
Plant overview
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 itself is highly automated and can keep running at capacity each shift without human intervention.
“A lot of time and effort went into getting the process control right – it’s more complicated than it looks,” Mr Bellamy says.
“For the final product we went with Metso screens with Trellex rubber media. We’ve done some fine-tuning of the screen apertures and we’ve achieved very good efficiency.”
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.
Liam Elsworth, Quarry Manager at Ormeau, says 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,” he adds.
Safety and efficiency benefits
The upgrade completely replaced the old processing plant, which was originally designed in the 1960s and had been moved to the site from its original location in South Australia.
Because the new plant has been built to modern standards, its design incorporates improved safety features such as guarding. The automation system also has safety functionality built into it, eliminating risks of overflowing media because the machine can perform controlled ramp-ups and shutdowns.
Maintenance has also been made easier, with better access to the installed crushers, screens and overhead cranes. A minimum number of screen types have been used, all with rubber media, to reduce the site’s spare parts inventory.
One of the criteria for the plant’s design was that the incoming power feed should not need to increase in capacity. Kai Kane, Boral’s Project Manager, says as a result, the energy efficiency has been greatly improved.
“We didn’t want to upgrade the existing four megawatt electrical in-feed,” Kane says.
“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.”
Environmental compliance
In order to gain approval to expand the quarry, Boral was required to meet a range of rigorous environmental requirements.
An environmental plan was put in place to minimise the impact on the local koala population, which includes maintaining an offset area of forest on the company’s land to the south of the site.
Boral has won awards for Ormeau’s storm water management plan, which was required to ensure the site could withstand a one-in-ten-year storm event.
“On the southern and eastern side of the site we have the Pimpama River,” says Liam Elsworth, Ormeau Quarry Manager.
“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 flood plain. A 60-metre 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.”
Waste, noise and dust were also key environmental concerns. The design of the plant means nothing is wasted with all raw rock converted to product.
The entire crushing and screening process is enclosed within buildings to limit noise, with automated water sprays installed to control dust.
Mr Bellamy says in addition to this, all of the conveyors are covered, and the screens have dust encapsulation.
“The secondary and tertiary crushers also have a foam dosing system, which works well and is automated and adjustable,” he says.
“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.”
Meeting expectations
The new plant has been pivotal to help the quarry achieve its throughput target, helping the quarry ramp up to 90 per cent of its capacity.
Mr Bellamy says the assets are performing as expected, with minimum performance requirements met earlier than expected.
“We have a very good relationship with the local Metso team,” he says. “The Metso installation supervisor was very good to work with. He put in long hours, making sure everything was right.”
According to Shaun Fanning, Metso Australia’s Vice President, Aggregates, the key to delivering the plant was early collaboration between Metso and Boral 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,” Mr Fanning says.