A vertical shaft impactor (VSI) designed and manufactured in South Africa is proving to be popular in the high-spec road base and concrete aggregates market in Australia.

The TwisterTrac VS350E from Pilot Crushtec is said to be ideal for the high-tonnage requirements of the crushing trains often deployed in this market. Finlay, the company’s dealer in Australia, notes that the machine’s ability to meet high throughput and high-spec aggregates requirements has helped it gain market traction.

Finlay Australia Queensland regional sales manager Justin Guilfoyle explains the success of the larger diesel electric TwisterTrac VS350E, noting that the country has high engineered specifications for road base and concrete aggregates. “While each state is slightly different in their gradation curve, there is generally a high requirement for 0.075 micron and 0.0425 micron, which is roughly 8% to 15%. In addition, there is a stringent shape obligation. These specs are for both state and federal projects where a tight envelope has to be met.”

Guilfoyle adds that cone crushers are not able to produce the stipulated 0.075 micron and 0.0425 micron sizes on quarries, while the crushing concept of the TwisterTrac VS350E, which uses rock-on-rock crushing principles, produces the required cubical material with broken particles that are cubiform, not flaky.

“The TwisterTrac VS350E assists in bringing up the bottom end of the material to meet these specifications, while shaping the rock. In concrete aggregates, there is a large call for shaped aggregate product, and this is an application where the machine has thrived. In addition, the TwisterTrac VS350E produces a high-quality manufactured sand, which is highly sought after in Australia,” explains Guilfoyle.

In addition, the machine can use anvils instead of the rock box, which results in a high reduction when used in a low abrasion application such as limestone.

The machine boasts an increased tonnage and high production capacity, with a rated capacity of 300 t/h, which can go up to 350 t/h when using a cascade bypass system, making it the largest mobile VSI on the Australian market.

Being a diesel electric machine, the TwisterTrac VS350E provides increased operational efficiency, while reducing carbon emissions. “Due to industry demand and changing requirements, we phased out the hydraulically driven TwisterTrac VS350 for the VS350E diesel electric version,” says Pilot Crushtec director technical support Jorge Abelho. “Given that a VSI by its nature is a power-hungry crusher, migrating to the diesel electric version was a necessary exercise. In fact, we have seen up to 20% fuel savings on the TwisterTrac VS350E compared with the VS350.”

The electric drive machine is powered by a Volvo TAD1651GE 16 litre engine delivering in excess of 400 kW of power, the TwisterTrac VS350E is said to have the biggest engine and generator compared with similar products on the market, allowing it to produce more tonnages.

“One of the reasons we are successful with the TwisterTrac VS350E is because the machine is 20% more efficient, yet it achieves 15% to 20% more throughput compared with the hydraulic version,” adds Guilfoyle.