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Wodonga quarry opens door to flexibility with washing circuit

 

During COVID-19, quarrying has proven its worth as an essential sector. On the Victorian border, activity has been especially high at Barro Wodonga Quarries, where the set-up of an integrated crushing and washing plant has defied the uncertainty of the pandemic. Damian Christie reports.

Barro Group is one of Australia’s great family business success stories. Since 1946, it has been a major independent supplier and distributor of premixed concrete, quarry and other construction materials products.

The company, founded by David Barro, today operates more than 45 sites, around 600 employees and hundreds of contractors throughout Victoria and Queensland. It has divisions in quarrying, concrete, landscape and building supplies, concrete roof tiles, landfills, transport and pre-cast panels.

In Victoria, Barro’s quarries fall under the banner of Mountain View Quarries, which was first established in 1962. These hard rock and sand quarrying plants are located in Point Wilson, Bacchus Marsh, Maude, Donnybrook, Nyora, Seymour, Wyndham Vale, Little River, Yea and Wodonga.

Wodonga is home to two Barro quarry sites: the Edwards Road sand pit and the Lincoln Causeway site, just south of Albury, which also houses the company’s Pronto concrete plant. In Wodonga, Barro produces sand for both concrete and asphalt aggregates, which is employed in road projects, buildings, housing and sub-divisions.

However, as Barro Group’s Victorian quarry operations manager Craig Banthorpe told Quarry, “our sites are needed for the supply of all materials for the entire Wodonga area”.

The plan is to run a new crushing, screening and washing circuit at the Edwards Road sand quarry, replacing ageing plant and equipment that included a sand washing system.

 “I remember talking to our operators about how much wear they had on the pump system,” Banthorpe said. “There were several things, including overhead slurry lines, that needed attention. We had big pipes running three metres overhead for long distances.”

Indeed, Barro seriously considered retaining the aged wash plant and only replacing the crushing and screening circuit. 

“When we started, we were just going to overhaul the crushing circuit,” Banthorpe said. “We were going to leave some of those lines in there and then it became obvious and natural that we should integrate the whole lot.”

The new plant would have to fulfil numerous requirements. These included the processing of up to 350 tonnes per hour (tph) of 0-100mm feed, varying feeds to three gradations and scalping of +50mm. The plant would have to operate in crushing or round stone “modes” – ie stockpiling 20-50mm round stone or crushing 50mm minus stone to the crusher – and blend aggregates with the “flip of a door”, to quote Barro staff, including the blending of manufactured sand with virgin sand deposits. It would also be required to produce up to eight different products, including 0-5mm natural sand, 0-5mm manufactured sand, and 3-7mm, 10-14mm, 20mm and 50mm aggregates.

The TWS integrated, modular crushing, screening and washing plant at Barro Wodonga. Photo: Sean King.

ALL IN ONE PLANT

Barro subsequently put out a tender for the full replacement of the processing plant at the Edwards Road Quarry site. The company considered several options, including mobile and static plant, before accepting a proposal from Terex Washing Systems for an integrated crushing, screening and washing modular plant. Barro retained its existing feed hopper and transfer conveyor which have been incorporated into the new circuit.

“We wanted a ‘one stop shop’,” Banthorpe explained. “We have kept a little bit of our old plant but we wanted to engage somebody that could look after all of the remaining parts of the project for us.”

James Murphy, the Australian and New Zealand sales manager for Terex Washing Systems (TWS), said that this “one stop shop”, integrated approach helped TWS win the contract. “It is Terex Materials Processing  from start to finish. We have a MC1150 cone crusher, feeder and surge bin in there, integrated into the same PLC and control system as our Terex Washing Systems equipment.”

At the time of press (November 2020), the newly-integrated Terex Jaques/TWS processing plant had literally come online at the Wodonga site. The circuit comprises an AggreSand 206 modular wash plant – comprising a primary three-deck, 6m x 1.8m (or 20’ x 6’) rinsing screen with an integrated sand plant, self-regulating sump tank, twin cyclones, 4.3m x 1.8m (or 14’ x 6’) dewatering screen, and radial sand stockpilers – backed by a modular MC1150 cone crusher with integrated surge bin and pan feeder, and another 6m x 1.8m (or 20’ x 6’) part-rinsing, aggregate sizing screen. All equipment is controlled by a Terex designed MCC and electrical control system.

The MC1150 modular plant comprises a 14-tonne TC1150 roller bearing cone crusher with a nominal head diameter of 1150mm which can accommodate fine, medium coarse and extra coarse manganese profiles and is powered by a 220kW motor. The galvanised steel support structure includes guards and discharge chute and houses the lubrication oil tank and hydraulic system. The MC1150 control system incorporates automated crusher closed side setting adjustment with tramp iron relief and hydraulic overload protection.

The crusher is fed by the 20-tonne surge bin, built from a heavy-duty steel modular construction with a Terex 800mm x 2500mm vibrating pan feeder.

A radial sand conveyor complements the TWS AggreSand 206 wash plant. Photo: Sean King.

BUILDING ‘LEGO’ BLOCKS

Although it is the first time a TWS wash plant has been installed on a Barro site, Banthorpe said Barro’s relationship with Terex Jaques, the Australian arm of Terex MPS, “goes way, way back. If you look at our large quarries at Wyndham Vale and Point Wilson, they are fundamentally Jaques crushing plant. We’ve built them separately but the crushers themselves are Jaques models, so we’re pretty familiar with the product.”

While the entire crushing, screening and washing circuit is of a modular construction, Murphy said it was more of a customised build. “It’s definitely not an off the shelf design, there was a period of engineering involved and sign-offs on the layout with Barro to ensure everybody was happy before we proceeded to manufacture,” he explained. 

“Even the 206 aggregate screen had a degree of customisation – it is more part-rinser than full rinsing screen so it can produce those three in-spec aggregate products while collecting and transferring the manufactured sand back into the wash system on the AggreSand 206. The oversize stone is allowed to either be stacked or can be recirculated back to the surge bin, so there’s some customisation in that. 

“Even the rear surge bin over the MC1150 cone crusher has saved us a considerable amount of ‘real estate’,” Murphy added. “We’ve elevated that surge bin and not had to fit another conveyor into the system. One of the biggest challenges that we had with this plant and the reason why there was a fair amount of customisation was to double the capacity of the old wash plant but on generally the same footprint.”

Nonetheless, despite the customised features, Murphy said the new Wodonga plant is versatile enough that it could be dismantled and reassembled in good time. “Modularity in its nature is things that can be bolted together,” he explained. “If Barro chose to pull that plant down and move it to somewhere else, they wouldn’t have to pull out the oxy torch and cut anything out. Everything can be unbolted back to smaller components and moved to a different location.

“There’s a lot of connecting bolts and pipework but everything’s built in the factory [at TWS’s manufacturing facilities in the United Kingdom] and broken down only to the largest component size to make it fit the container in a cost-effective manner. So when it comes to site, we’re pulling out parts that have cyclones and pipework already mounted onto them and just building Lego blocks and it goes together relatively easily.”

‘DIVVYING’ UP PRODUCTS

Murphy added the AggreSand 206 has always offered producers high throughput capabilities on “a relatively small, compact, modular footprint. It’s versatile because upon ordering you can configure it with two or three decks on the rinsing screen, one or two grades of sands to be produced, and even try double or triple washing systems for applications where the raw material has a higher clay content and it’s more problematic to process to meet a specification. We can also replace the standard hydrocyclones on the AggreSand 206 with more specialist, dewatering style separators, with vacuum bleed adjustments on the underflow density. The benefit is producing a cleaner, drier product before it even hits the dewatering screen, thus further lowering the soluble clays content in the final washed sand.”

Murphy said Barro required the processing of an alluvial gravel feed at a target tonnage of up to 350 tph. Therefore, he was confident the AggreSand 206 could achieve that throughput with high screen efficiency by “divvying” up products. The triple deck screen allows aggregates to be sent to the surge bin and the sand is separated to the back of the sand plant. The middle deck is used to relieve the bottom deck bed depth, ensuring all the sand available is recovered at the first chance of asking.

Another requirement was upgrading the plant to operate in two modes– to, as Murphy said, “produce rounded, decorative stone and at other times, crushed stone for concrete or asphalt aggregate. We offered that feature on the modular MC1150 cone crusher, so that any of the stone could by-pass the crusher via a chute, and all of that could be processed over the part rinser screen. That also means we’re not using power when we don’t need to run the cone crusher.

“Barro wants to be able to blend the manufactured sand into natural sand or vice versa, if the market dictates it,” Murphy said. “The AggreSand, with its dual pumps and hydrocyclones in a two-grade format can process those two separate materials through process streams in parallel. The materials can be blended at the cyclone’s underflow box and then again, if need be, on the dewatering screen’s discharge chute. This gives the operator versatility, and understanding of how much to blend across to meet a spec, should that be the requirement.”

POWER, AUTOMATION

Another challenge for TWS was to marry the integrated plant’s power requirements. Murphy said the standard AggreSand 206 offering has its full electrical system fitted at factory prior to dispatch. A “plug and play” system allows the cabling to be routed and connected to a control panel on the chassis during on-site installation. However, on the Barro plant, they have included several additional conveyors, a whole crusher, a rinsing screen, etc, so for that size of control panel, we have offered “a separate containerised MCC control room and Terex supplied the full electrical install and cabling on-site”.

The integrated plant is highly automated and can be overseen by the one operator. “On the automation side of things, he’s going to have full remote access for stop/start control of his feeder,” Murphy explained. “There’s both auto-start and auto-stop features, meaning a one-push button to start the plant and it starts up in a pre-determined sequence 

“On the cone crusher side, we have a surge bin that operates on high and low level settings, so the crusher can be choke-fed to operate at optimum efficiency for reduction and shape. The cone crusher will automatically stop the feeder if there’s not enough product to run it for a length of time, and it will start again once the hopper is full. In the same vein, we have a transfer pump, whereby the manufactured sand is pumped back to the AggreSand. There are flow meters around the plant, and if for any reason, the water coming into that tank stops or reduces, we have a low level setting on the flow meter which disengages the pump so it won’t run dry. All of the inlet pressures on the cyclones and manifold water pressures on the fresh water delivery are recorded as well. The features are all there, thanks to the smarts in the Terex MCC and electrical control system.”

The automation and control system is aided by cloud-based data collection. “All the data and tracking of the plant’s performance can be uploaded to the cloud so anybody in Barro’s head office can access the plant, to see how many hours a day its running and how many tonnes of feed it’s processing,” Murphy added. “From a maintenance perspective, they can also track how many amps are being drawn on any of the motors, etc. This becomes useful in detecting imminent bearing failures for example.”

FEAR OF THE UNKNOWN

TWS and Jaques provided the Barro Wodonga team with the expertise to install the plant – a task made more challenging by the disruption of COVID-19. Indeed, Banthorpe said Barro would have installed the plant much earlier in the year, had the pandemic not reared its head. However, the uncertainties in the international market meant Barro could not afford to dismantle its old sand plant if the delivery of the TWS equipment was delayed by months, not weeks.

“As it turned out, it probably wouldn’t have impacted us but we didn’t know at the time,” Banthorpe reflected. “It was the fear of the unknown, we couldn’t afford to stop our existing plant. We decided to wait until everything arrived – and that was the right decision.”

For Murphy, in particular, the closure of borders to Victoria meant he could not physically participate in the build and the installation with Terex Jaques’ Victorian-based personnel and Barro Wodonga’s operations team. As has become the norm during COVID-19, he participated in a virtual capacity. 

“We put a few CCTV cameras on the deck, which I could monitor from my ‘control room’ in Brisbane,” Murphy said. “There’s a remote dial-in feature, so I can pull up the PLC display of the plant at Barro Wodonga on my PC or iPad and tell you if the sand plant is running right now. Modern technology allowed us to still deliver the project successfully, on time and on budget. COVID-19 has thrown up challenges but nothing that can’t be overcome.

“A lot of our training and familiarisation with the PLC and the control system is happening now,” Murphy added. “Barro’s regular maintenance contractor has been involved in the build process. It’s been a benefit to TWS as well as Barro because he’s become very familiar with the plant as he’s been building it and he’s going to be around for the next few years to maintain it.”

Banthorpe complimented Murphy for his commitment to the project in absentia. “James couldn’t be there but he did the next best thing and was still able to supervise it,” he said. “It’s a credit to TWS that they’ve put it all together, given those limitations. I know James would have preferred to be there but in the end it was a speed bump in the road. The assembly of the plant has all gone to plan.”

Nor was there ever any serious concern about the availability of high volume components, parts and equipment through TWS and Jaques at the onset of COVID-19. Barro Group has been assured that in the event of breakdown or regular maintenance, there is sufficient stock available for producers.

“Terex Jaques’ head office down at Dandenong South is where we support Barro Wodonga,” Murphy said. “We also have a comprehensive stock of TWS parts in our Wetherill Park branch because there are four AggreSands in NSW. Jaques took on TWS in 2018 and extensively trained its technicians and management staff to maintain and service our customer base. It’s definitely something we can service locally from Victoria, should the borders be closed again.”

The Barro plant is controlled by a dedicated PLC and electrical power system. Photo: Sean King.

EMPLOYEE BUY-IN

Although the integrated plant at time of writing is in its “infancy” at Barro Wodonga, Banthorpe said the site’s operators were pleasantly surprised at the sand plant’s performance.

“Their reaction was ‘Wow! I can’t believe how dry the sand is!’” he exclaimed. “The product we were producing in our old sand operation could be very wet, so they’re getting used to the new technology. They were also impressed with the cleanliness of the stone.”

Nonetheless, Banthorpe said Barro Group is pleased the new integrated plant has come to fruition and he said the company’s selection process provides useful pointers for other quarrying operations. “Terex Washing Systems was successful because our people – the site manager and the site supervisor – felt most comfortable with James’s proposal, and they also felt a level of familiarity with the components being used.

“You really need buy-in from the people that are operating the plant, especially when it’s done at a distance. It’s done in Wodonga, and most of our business is in Melbourne,” Banthorpe added. “I can’t stress that enough. You need that buy-in and ownership of the selection process, and that involves people who will operate the new plant.”

In turn, he and Murphy agreed that if the site personnel know exactly what plant and products they want, the task is simpler and creates flexibility for future circumstances.

“Another piece of advice for speccing up for plant like this,” Banthorpe said, “is to allow for lots of different chutes and diverters that create plenty of options. Try to build in as much flexibility as you can. Build it for what you’ve always done but make sure you have the ability to make changes.

“For example, after the screen where we’re making aggregates at the end, we have a last chute that leads to nothing. There isn’t a conveyor in place but we deliberately said, ‘Let’s just leave it there and one day we may have a need for making a product that we can chute out there.’ Everything’s in position, and all we need to do is put a conveyor there. 

“It may be early days but I feel confident we have lots of options,” Banthorpe concluded. “We’ve had lots of discussions about the concrete sand and aggregates we have to make but we have a lot of flexibility with what we choose to do in that space.”