Rocla is no stranger to the Australian construction materials industry. It has been a supplier of concrete solutions to the industry since the early 1920s when two close friends – Walter Robinson and Heaton Clarke – first registered the company and combined the initial letters of their surnames to create the Rocla brand name.
Today, Rocla, which has been a subsidiary of New Zealand’s Fletcher Building Group since 2005, is involved in infrastructure, mining, buildings and subdivisions, where it provides a multitude of products, including building columns, foundation piles, sewer access and pump systems, railway sleepers, stormwater pits, pipes and power poles.
Since the 1960s, the company has been a national supplier of building and construction sands. The Rocla Quarry Products division owns 15 quarries in five states that produce specified sands for concrete, mortar, plaster and fill. It also produces specialised dried sands, which is used, amongst other applications, for glass manufacture and in foundries – which in a cyclical twist fabricate and provide the grades of steel for the plant and equipment needed to crush those same sands in the first place!
CALGA QUARRY
The Calga quarry operation, on the New South Wales Central Coast, approximately 62km north of Sydney, has been operating for two decades but has been owned by Rocla for 10 years. The quarry’s current consent is for 400,000 tonnes per annum and its current output is around 250,000 tpa.
According to Angus Richmond, the NSW/Queensland regional manager for Rocla Quarry Products, the company is extracting Hawkesbury sandstone, which is ripped with a dozer and then sent to a crushing circuit and washing plant for processing. “From that, we produce a concrete sand for manufacturing, a factory sand for building material products and a brickie’s sand for brickie’s mud,” Richmond added.
Rocla has acquired immediate neighbouring land in Calga and has submitted a development application for a quarry extension to the NSW Department of Planning. The extension is for another 10 million tonnes of sandstone and to raise its consent to one million tpa. This would give the quarry a life expectancy of around 25 years, give or take the speed of production.
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In 2013, the Calga wash plant underwent a substantial upgrade and makeover with the assistance of Scope Engineering, which specialises in the design, manufacture, installation and sourcing of Australian-made turnkey fixed plant solutions. With the aid of Scope, Rocla replaced an old wash plant with an output of 150 tonnes per hour with a wash plant that could generate 220 tph of product.
Richmond, whose responsibilities at Rocla also include operations excellence utilising lean manufacturing methodologies, explained there were three reasons why Rocla opted for the new wash plant. “The first was increased production, the second was life cycle replacement and the third was that the old plant had to be relocated anyway as part of the mine plan staging,” he said. “We needed to mine where the old plant was. It was a combination of those reasons – for mine planning, for production capacity increase and life cycle replacement.”
He added that the plant replacement was also designed to meet customer specifications, “to produce a specified
sand that has consistent gradings and is low in silt”.
The wash plant that Scope installed at Calga comprised of a rotary tumbler (which increases the attrition of the sand to remove silt), a screen, a wash tank, a classifier, two cyclones in parallel, two classifiers in parallel and a dewatering screen.
The aggregate flows through the circuit in that order after the sandstone is ripped up by dozer and transferred to the wash plant. At the end of the washing circuit, the washed sand is transferred to automated radial stackers that can be rotated to 180 degrees. Richmond estimated that the main stockpile of sand coming off the radial stackers is around 10,000 tonnes. The brickies sand raw feed is deposited off another stacker at around 2000 tonnes.
{{image3-a:r-w:250}}He added that the installation of the new washing circuit at Calga was smooth and both Scope and Rocla worked well together. “The feedback from my engineering team is that the process went very well and there were no major technical challenges at all to construction or to time and budget,” Richmond said.
The upgrade, according to Richmond, has also made Rocla Calga now capable of recycling its processed water, something that didn’t occur when the old sand plant was in place, and of being able to further reduce the silt content in its sand and optimise its sand products for its customers’ requirements.
CLIENT ENGAGEMENT
Paul Fletcher, the managing director of Scope Engineering, based in Narangba, Queensland, stated that the company has been involved in plant design, manufacture and installation since 1999, when it first established a manufactured sand plant for Boral’s Stapylton Quarry in southeast Queensland.
It can provide all manner of products to suit its customers, including crushing and screening stations, sand washing plants, conveyor systems, blending and batching plants, concrete recycling plants, reclaim tunnels, silos and purpose-built industrial buildings.
In the last five years, Scope has been involved in designing, manufacturing and installing a fixed basalt crushing plant at Emerald for the Central Highlands Regional Council, a fixed granite crushing plant for Halkitis Bros in Darwin and a number of jobs for some of the major construction materials companies, including Boral and Hanson. Scope has worked with Boral on plants in Darwin and Mackay, and with Hanson on plants in Biloela in Queensland, Red Hill in Western Australia and more recently in East Guyong, NSW.
Fletcher, whose own experience in the quarrying industry spans 35 years, explained that while every project was different, the step by step process for establishing a new turnkey plant for a customer was essentially the same.
“The first stage of this process starts with the client,” Fletcher said. “They need to establish the market requirements, the product range and the annual production they anticipate. Stage two is to generate a flow chart based on this information.
Stage three is to develop a plant layout based on site civil considerations, environmental constraints, availability of services and client equipment preferences.
“The preliminary plant layout is then forwarded to the client for comment and approval. Budget costings can then be established. Once the design and budget are agreed upon, final civil, mechanical and electrical design drawings can be generated for manufacture.
{{image4-a:r-w:250}}“Simultaneously the site civil works are prepared and civil foundations are placed,” Fletcher explained. “As manufactured items are completed as per schedule of works, items of plant and equipment are delivered and installed. Electrical works and additional services are installed simultaneously. On completion of mechanical and electrical works, the commissioning process starts.”
Fletcher added that Scope uses five members of its own design team to produce working drawings of the new plant and have them certified by qualified design engineers. Scope engage and work in conjunction with contract electrical teams with mine-compliant backgrounds to ensure that the electrical works are fit for purpose.
“The client usually handles all council approvals and permits,” Fletcher said. “They engage power providers where applicable. Generated power can be required in remote areas. We are responsible for ensuring all mechanical, structural, electrical and civil design items meet or exceed all relevant Australian standards with a heavy emphasis on safety compliance. We work closely with all of our clients on the plant design to ensure total customer satisfaction. The design is being continually reviewed to ensure this.”
The duration of a given assignment will vary between six and 18 months, depending on the size and complexity of the project. The build at Rocla Calga was relatively straightforward, Fletcher said, compared to another recent project which required Scope to not only install a full plant but to place it within large sheds for dust collection and noise mitigation purposes, with conveyor sections in turn being covered and fully guarded. Overhead cranes were also provided in two of the main buildings.
“The unique challenge was the arrangement of the equipment in the buildings to allow maintenance access to all areas of the plant and the provision of removable roof sections to facilitate removal of major components,” Fletcher explained of the project. “There also had to be belt feeders in the main screen house to create a blending plant facility that could produce road base to main road specifications through normal crushing and screening operations.”
AUSTRALIAN-MADE
Fletcher is extremely proud that Scope’s plants are fixed applications. Fixed plant is essentially a series of crushing and screening modules that form a crushing circuit and are designed for long-term operations. Cheap imported modular units and mobile plant items are less productive due to lower efficiency rates. “If you’re going to be on a site for a considerable length of time, the fixed plant option is the best because it’s designed to give people the access that they need to maintain it properly. Hence, the reliability is far better. A lot of the modular stuff today is brought in from overseas, whereas we’re trying to use Australian materials and continually improve our service and design capabilities.”
{{image5-a:r-w:250}}He stressed the importance of Scope’s plant and equipment being wholly Australian-made. “Other tenders use imported steel,” Fletcher said. “However, we’ve been able to win a reasonable amount of projects that use Australian-made steel. I try to promote that as a feature of ours. It’s important that we maintain our steel fabrication base and skills in Australia. If we’re not given the opportunity to do the fabrication then we won’t be training apprentices and we’ll be losing those services and skills offshore.”
Indeed, Angus Richmond cited Scope’s Australian credentials as one of the factors for Rocla’s appointment of Scope at Calga Quarry. “Scope has a proven ability in plant design, and the quality of their work was known to us,” Richmond explained. “They’re an Australian company with good support services, and they’re able to support us with after market assistance and maintenance.”
Richmond added that the sand wash plant is also “easily maintainable” because of its accessible and safety-conscious design.
To meet the additional capacity that is anticipated from its extension project, Calga Quarry’s plant and equipment will undergo another upgrade in the near future. “We plan to install an additional wash tank to further reduce silt volumes. We are also planning to add fixed crushers at the start of the process in order to improve yield to make more sand out of our raw material,” Richmond said.
He added that Scope are less likely to be involved in the design of this upgrade because it is being conducted in-house by Rocla. “The additional wash tank is likely to be similar to the existing one,” Richmond said. He added, however, that he anticipates that Rocla and Scope will continue to partner on plant design and installation projects as needs arise.