Blog

Oct 19, 2024

Astec delivers generational innovation - Quarry

Quarries are constantly looking to improve their bottom line. Astec’s 2818VM Portable High-Frequency Screening Plant is helping them achieve it. Few materials have generated as much conversation in

Quarries are constantly looking to improve their bottom line. Astec’s 2818VM Portable High-Frequency Screening Plant is helping them achieve it.

Few materials have generated as much conversation in recent years as sand.

The product that has been the backbone of many construction materials, including concrete, asphalt, and more, is in short supply globally.

According to The United Nations Environment Programme, natural resource extraction tripled between 1970 and 2019. As part of that, the organisation estimated between four and eight billion tonnes of marine sand are extracted each year worldwide.

“The path we are on now is simply not sustainable,” said Pascal Peduzzi, director of GRID Geneva, an environmental information centre hosted by the United Nations Environment Programme (UNEP).

“We need countries … to consider sand as a strategic material.”

The sand shortage is not simply a topic for discussion; it can have practical consequences not only in the quarrying sector but also in infrastructure projects.

So the race is on to find new ways to create manufactured sand, the quarrying industry’s answer to solving the shortfall of natural sand.

Original Equipment Manufacturers (OEMs) also have a role in the solution, and Astec has delivered a “generational” innovation that could unlock the future for quarries.

The 2818VM High-Frequency Screening Plant, launched at ConExpo in 2023, can transform fines and crusher dust into valuable manufactured sand.

“Most quarries in Australia have a surplus amount of crusher dust, and Australia, like all other countries around the world, is having an issue with natural sand resources,” Adam Gordon, Astec Australia’s business line manager for material solutions, told Quarry.

“[The 2818VM] can take manufactured crusher dust and up-value it by removing some of the 75-micron powder to make a compliant manufactured sand.

“We’ve got a big demand for sand, and while there have been other products on the market to try and make a use for [crusher dust], sand availability is still dropping. At the same time, all quarries need to maximise their return per tonne. The capability of the 2818VM has created a win-win, for both operators and the environment.”

The 2818VM debuted as the widest high-frequency screens on the market. It features a 2.4m x 5.5m top deck and 2.4m x 3.7m bottom deck with externally mounted vibrators at the tappets’ ends for easy maintenance.

The screen has hydraulic operating angle adjustment, a fines collection hopper, top- and bottom-deck discharge chutes, and an aggregate spreader. The PTSC2818VM Trailered model also features a nominal 1.3m x 11.5m delivery conveyor with hydraulic drive and full-length skirtboards. The robust chassis has manually operated support legs, outriggers for additional support, and folding walkways along the screen.

But it is another aspect of the Astec 2818VM’s unique design that enables it to generate a higher G-force and a more aggressive screening action.

The top deck’s 14 adjustable exciters can all be individually controlled. Each one can be finely tuned to screen the specific amount of material above it on that section of the screen deck. It’s an innovative design that is delivering increased screening capacity and efficiency.

“This 2818 is the next evolution in screening. Increasing the motion and the screening forces, and combining that with greater capacity is a big step forward,” Gordon said.

“The 1.8m wide model has one exciter over this width; in this model, we have two exciters over 2.4m. We’ve effectively created a 50 per cent increase in excitation and RPM.”

In comparison, a traditional screen, whether a single or dual shaft, operates on a single motion for the whole screen. This can result in an uneven spread with the feed end being overloaded, the middle being well set up, and the bottom end having too much motion, causing the material to jump around.

Gordon said the 2818VM offered increased customisation for the operator.

“We can match the forces, the frequency and the RPM directly in proportion to the amount of material on the screen media above that section,” Gordon said.

“This [capability] makes every exciter on the machine like a single-shaft incline screen.

“When we have material starting up the top, we can set those two exciters up for that amount of feed, RPM and stroke. As it drops down, we can set the next one to a slower RPM and stroke because the material above it is less, and then we can drop the next one down again.

“We have seven times the adjustment capability across the whole screen compared to a standard incline screen.”

Gordon estimated that most quarries have 20 per cent of their material feed turned into crusher dust. For example, a 500,000-tonne-a-year quarry would generate around 100,000 tonnes a year of crusher dust. If rehabbing costs $3 per tonne, the quarry would incur $300,000 in costs. In this example, quarries processing that crusher dust could sell it as an up-valued manufactured sand product for $25 per tonne. So instead of dealing with a loss, they could add $2.5 million to their business’ bottom line.

Across the Tasman Sea in New Zealand, quarries have already taken advantage of the concept with two Astec 2818VM screening plants in the market.

In that country, quarries are being limited, or in some cases prohibited, from extracting sand from natural sea deposits so there is an even greater need for manufactured sand.Lance Cockle, operations manager at Turnco Engineering – Astec’s dealer in New Zealand – worked with the customers to ensure the 2818VM suited their applications.

“One of the units we’ve sold has gone into a quarry that generally makes concrete aggregate, 3mm and above,” he said.

“But they’re very aware of the sand shortage and realised they can make that product with the material they have. They can dig out the rock and use the 2818VM to separate the particles.”

Cockle said the way the 2818VM moves the screen media separates it from other screening units on the market.

“With the traditional screen, while the whole thing moves as one unit, the High Frequency model flexes the screen media,” Cockle said.

“Previously, those drivers for moving the screen media have been inside the actual screen frame, so you have to get inside to adjust them … [with this one] all the drives and everything are accessible from the outside.

“It makes for easier maintenance, easier accessibility, ease of tuning it to suit the application. It is a much better system because it handles those much finer particles at a much higher volume.”

There is an increasing expectation that quarries align with environmental, social, and governance (ESG) responsibilities from both local communities’ and legislative perspectives. The increased focus on ESG can be seen throughout the industry, from the push towards lower fuel burn for machines to using recycled products in construction materials.

Gordon said utilising more crusher dust could be a way for quarries to meet this expectation.

“It is a product that is always going to exist simply through the process of crushing. But by turning that crusher dust into manufactured sand or a sand replacement, we are preserving natural sand deposits,” Gordon said.

“The more crusher dust we process, the less natural sand we need to touch. From the environmental, social and governance points-of-view, this ticks all the boxes.

“It’s a benefit to the whole community; we’re using more of the material and getting a greater economic return, rehab will be easier, and the community will be better served by quarries using more of the existing resources.”

In Australia, Astec has supplied smaller versions of the 2818VM – the GT2612V – to seven customers in different applications. They all use the screening plant in mobile – tracked applications to transform their crusher fines into manufactured sand. Other quarries on Australia’s East Coast are using the smaller models to generate proof-of-concept for the manufactured sand.

And the benefits of the Astec screening technology extend into other applications. Two 2618VM screening plants have been working for years in a limestone quarry in Geelong. Astec also uses its smaller high-frequency screens on its trailered asphalt processing plants, where it has increased the reclaimed asphalt pavement percentages in asphalt mixes.

“Astec designed these screens to improve the yield of our customers’ resources and to turn crusher dust into a viable sand alternative,” Gordon said.

“Not only have we achieved that aim, we’re also working together with our customers to help preserve our planet’s natural resources.”•

For more information, visit astecindustries.com

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