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Articles from CRUSHERS PLANT & EQUIPMENT (735 Articles)

Index Group’s Dorrigo Quarry plant has played a significant role in providing materials for the Pacific Highway upgrade.
Index Group’s Dorrigo Quarry plant has played a significant role in providing materials for the Pacific Highway upgrade.

VSI proves itself right choice at mid-north coast quarry

An independent quarry operation on the country’s mid-north coast has teamed up with a major supplier to address the challenge of delivering a well shaped and tightly specified roadbase for one of Australia’s most ambitious road projects.

The Australian Government has committed to investing in the country’s highways and roads, and to embarking on the biggest infrastructure investment program in Australia’s history, announced as part of the 2014-15 budget.

This is good news for those involved in highway construction and maintenance. However, it presents some challenges as well, especially in remote areas where the availability of good, well shaped aggregate is becoming increasingly harder to source.

Remote infrastructure projects can be serviced by transporting finished aggregates from established quarry operations but transport costs often become prohibitive to this solution. Consequently, subcontractors need to look for small, local deposits of hard rock raw material to process aggregates and sand needed for the project. For this approach to be cost-effective, equipment selection is extremely important, to efficiently produce the required material with the least number of machines.

Adding to the difficulties of finding suitable raw materials close to remote projects, another major issue aggregate producers face in New South Wales is meeting the Roads & Maritime Services department’s strict requirements for DGB20 sub-base materials for pavement roads. Traditionally, many producers seeking to conform with DGB20 requirements have had to buy additives or fillers such as decomposed granites or fine sand to ensure the grading of the finished product meets the standards.


Weir Minerals’ Trio vertical shaft impactors (VSI) are proving a sound equipment choice, capable of delivering products that meet strict requirements and the versatility contractors need to minimise capital investments.

The Trio VSI utilises the most advanced design platform, making it the most flexible impactor to meet the demanding needs of processing not only coarse aggregates but also manufactured sand, mineral ores and industrial powders.
One organisation to benefit from a Trio VSI is the Index Group, which is involved in the Pacific Highway upgrade in NSW’s mid-north coast region.

When looking to deliver aggregates, sand and DGB20mm roadbase to the project, Index Group needed to find the best solution to produce well shaped aggregates while minimising the number of crushing stages in the circuit. On initial start-up, the Index Group’s Dorrigo Quarry utilised a track-mounted primary crusher, modular secondary cone crusher and a competitor’s VSI to generate the roadbase material necessary for the road’s foundation.

The team at Index Group knew they did not have the most efficient process and turned to
Weir Minerals for assistance. The installation requirements were to achieve desired throughput levels, produce correctly shaped aggregate and most importantly produce DGB20 that would conform to the stringent RMS specifications on single pass while minimising capital costs.

Based on Weir Minerals’ recommendations, the Index Group purchased, installed and commissioned a Trio TV95 VSI at the Dorrigo Quarry, with a rock-on-rock chamber and rotor configuration. The rotor installed in the VSI was initially a 40-inch, four-port rotor that allows a 63mm top size.


A previously trialled competitor VSI generated a maximum of 36 per cent passing 2.36mm. The Trio TV95 VSI achieved 41 per cent passing 2.36mm in single pass, an increase of 14 per cent over the previous yield of the quarry. This significant increase was due to the oversized rotor and improved geometry in the 40-inch rotor, coupled with its four- port rotor design. The design resulted in better size reduction when compared with the traditional three-port rotors supplied by competitor machines.

The TV95 VSI is installed as a tertiary VSI and is fed 100 per cent passing 25mm of crushed stone from the primary jaw and secondary cone crushers. By running all the 100 per cent passing 25mm through the VSI, all particles are acted upon in the crushing chamber, producing well shaped coarse and fine aggregates and sand.

As production requirements shifted from generating roadbase materials to aggregate and manufactured sand, Dorrigo Quarry’s output needed to change. The flexibility of the VSI made this easy. The rotor was changed from a 40-inch to a 32-inch with five ports.

By moving to the smaller rotor, Index Group gained an increase in production of coarse aggregates and generated a purpose-made manufactured sand to be used in the production of concrete.

Since installing the Trio VSI, Index Group’s Dorrigo Quarry has delivered consistent well shaped coarse and fine aggregates, manufactured sand and DGB20mm roadbase material without the need for make- up additives to meet specifications. Average throughput achieved is 250 tonnes per hour, with the rotor tip life averaging between 50,000 and 60,000 tonnes produced.

“The results achieved at Dorrigo Quarry are a great example of the performance we consistently see from our Trio VSIs,” said Tony Barton, Weir Minerals’ regional sales manager for Australia and New Zealand.

“The flexibility of these machines means we can continue to work with our customers to ensure the VSI is efficiently producing high value shaped product throughout the different stages of a project, making it extremely cost-effective."

Source: Weir Minerals/Trio.

Trio’s VSI machines are capable of delivering products to strict requirements.
Trio’s VSI machines are capable of delivering products to strict requirements.

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Thursday, 17 October, 2019 1:51am
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