Tegra Australia is a quarrying and concrete business that was established by the Sargent family in 1964 and has serviced southern New South Wales and the Australian Capital Territory for the past 50 years.
It runs three quarry sites in Braidwood, Gundagai and Jugiong and seven concrete plants in Boorowa, Braidwood, Gundagai, Harden, Tumut, Yass and Young.
Tegra produces and supplies a variety of end products, including aggregates, sands, soils, river stones and pebbles and pre-mixed concrete products to builders, local government, small backyard projects and contractors engaged in road and infrastructure projects.
It also manages a fleet of agitators and haul trucks as well as a mobile concrete batch plant that is available for hire throughout NSW and the ACT.
At Tegra’s Jugiong Quarry operation, located between Gundagai and Yass, the plant processes a rare riverstone from 300mm minus and produces a range of end products, including crushed concrete aggregate in 5mm, 7-10mm and 14-20mm blends and a decorative round stone in 6mm, 8mm, 10mm, 14mm, 20mm, 35mm and 50mm.
This includes the synonymous 10mm Jugiong brown pebble. The quarry also produces coarse and fine concrete sands, brickie sands, crusher dust, topsoil and garden mixes, landscape soils and drill blends of brick and paver products.
Depending on workloads, the quarry’s annual output is up to 100,000 tonnes per year.
Since the mid-1980s Tegra Jugiong has operated a Goodwin Barsby 36” x 12” jaw crusher, with a Lokomo G158 cone crusher operating since 1993.
While the machines continue to operate today, over time it became clearer that they had a low output – only about 70 tonnes per hour between them – and could not necessarily deliver the precise particle shape needed to meet exact concrete compressive strength specifications.
As a result, in 2008, Tegra Jugiong sought to purchase a vertical shaft impact (VSI) crusher that could be incorporated into the quarry’s crusher circuit and deliver the desired particle shape.
ROCK ON ROCK IMPACTOR
Tegra approached Crushing & Mining Equipment (CME), which supplies a full range of crushing equipment nationwide. This includes CME’s home-grown Auspactor VSI crusher, which is available in six single- or dual-drive models with throughputs from 75 tph to 600tph.
According to Walter Turner, CME’s manager for Auspactor, the rotor was originally developed to overcome the shortcomings of other designs on the market and offer a “free flowing” device to accept “all rotor feed” that would be easy to maintain and provide cost savings to the customer. {{image2-A:R-w:250}}
The Auspactor rotor was subsequently launched and retrofitted to various other brands of VSI in use in Australia.
The success of the rotor encouraged CME to develop its own range of VSI rock on rock machines for the local market.
“The design parameters of the Auspactor VS100RR, VS200RR and VS300RR sought to use all rotor feed to produce fines more efficiently for many applications including mining, while retaining the ability to shape aggregates at high throughput rates for concrete and asphalt applications,” Turner explained.
The major feature of the Auspactor VSI is its rotor fabrication, which has no exposed fasteners and reduces wear. The rock-lined rotor accelerates discharging aggregate to 40 to 60m per second (m/s), creating a high velocity rock on rock impact action that causes the material to shatter and abrade, to provide the desired particle shape.
The Auspactor is suitable for the shaping or size reduction of a variety of materials, including abrasive/wet feed. In addition to the shaping or resizing of aggregate for concrete and asphalt, the Auspactor can also be used for the manufacture of graded sands, fine crushing of limestone and gypsum and processing of recycled aggregates, including glass, tiles, bricks and concrete.
The machines can be supplied in various configurations, ranging from a bare crusher through to modular plant assembly complete with legs, skid base, access platform and ladder. Turner said this gave the customer the flexibility to adapt the machine to suit each individual quarry application.
“Some machines may see out their lives in a fixed quarry building while other skid-mounted machines will be moved around a mine or quarry or from site to site when needed,” he added.
BABY BROTHER
The smaller production rate at Tegra’s Jugiong Quarry required a smaller VSI than was available on the Australian market at
the time.
“This site had been considering the use of a VSI for some time but the production rate was borderline for the then smallest available Auspactor VS100RR machine,” Turner said. “Via another customer, the opportunity arose for CME to design and build a smaller Auspactor VSI machine to form part of an innovative, compact, underground crushing and processing plant.
“The success of this new machine, known as the Auspactor VS75RR, led to its introduction at Tegra quarry.”
The VS75RR could therefore be described as the “baby brother” of the Auspactor line-up. Compared with its other siblings – the single-drive VS100RR and the single- and dual-drive VS200RR or VS300RR – the single-drive VS75RR has a maximum power capacity of 75kW and a maximum feed of 45mm and can produce up to 75 tph.
Turner added that the Auspactor VSIs could be supplied with variable speed drives (VSD) to account for “changes in feed material or product spec requirements”. {{image3-A:L-w:250}}
As Tegra was not proposing a complete overhaul or replacement of its crushing plant, it was relatively simple to “retrofit” the Auspactor into its pre-existing plant, to reduce maintenance costs and improve shape and productivity.
Since being installed in 2008, the VS75RR at Jugiong Quarry still acts as the tertiary crusher in the operation’s plant set-up,
with the Goodwin Barsby jaw and the Lokomo cone as the primary and secondary crushers.
Between them, the three machines have a throughput of 130 tph – 50 tph of coarse sand, 20 tph of round river gravel and 60 tph of crushed aggregates.
Turner said the installation of the Auspactor at the Tegra quarry was simple.
“In some applications, tertiary HSI crushers have been removed and replaced by Auspactor machines to reduce overall maintenance costs,” he said.
“In other plants, such as [the] Tegra quarry, where traditional jaw and cone crushers were in use and improved product particle shape was desired, an Auspactor was quite simply installed.
“Powered by a stand-alone diesel generator set, the skid-mounted Auspactor was positioned in a convenient location alongside the existing plant. A new conveyor from the existing primary screen was installed to feed the Auspactor -22/+3.15mm material, while a new stub conveyor and transfer conveyor transported the product to the existing final sizing screen.”
Indeed, Turner emphasised that in the case of a customer such as Tegra, where the existing plant was functional but the product shape needed improvement, “it was much more financially viable to add an Auspactor machine as opposed to building an entirely new plant from scratch”.
Turner said CME monitored the VS75RR’s performance in the early stages of its usage to “ensure that it was doing the job it was intended for at a cost-effective price. The weaker particles in the feed to the Auspactor were turned into sand as confirmed by the increase in sand production.
“The Auspactor VSD allowed the rotor speed to be tuned to best suit the balance between sand production and acceptable product particle shape. The improved aggregate strength and shape resulting from the Auspactor installation proved beneficial to the customer’s concrete business.”
CUSTOMER FEEDBACK
Mick Cross, who is the quarry manager at Tegra Jugiong, said the quarry chose the VSI primarily because “we had a lot of weak particles in our concrete aggregates, like decomposed granite type products, which we would then have to break up”.
He said the Auspactor was most suitable because it was one of the few VSIs small enough to suit Tegra’s operation. He added that the Auspactor also offered (and continues to offer) ease of maintenance, while spare parts were readily available off the shelf from CME’s inventory.
After six years and almost 7000 hours of virtually uninterrupted operation, Cross could not be happier with the Auspactor.
“The biggest benefit for us has been the improved concrete,” he said. “We had to improve the particle shape and as most of our material goes into concrete, we had to get rid of the weak particles.
“The final product is now a lot better than it used to be. We’ve compressed the strengths of the concrete due to the improved aggregate quality and we’ve been able to sell an improved product.”
Cross was also complimentary of CME and Turner, who is in regular contact with Tegra to ensure the Auspactor is fully functional and to provide assistance where required.
“As the Auspactor is Australian designed and built by CME, we are usually in regular contact with our machine users, assisting and advising them with any wear issues that may evolve over time,” Turner said.
“Information and experiences gained from this allow us to further improve our machines and rotors and, where possible, we strive to make any improvements backwardly compatible so as to ensure long-time customer satisfaction.”
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