It’s been a mainstay of the Australian quarrying and recycled aggregates sectors for almost 15 years – but now a popular portable crushing and screening plant has had a makeover for Australian conditions. Damian Christie reports.
The portable ProSizer plant, by Astec, is no stranger to the Australian construction landscape. In fact, it has been a popular recycled aggregates and asphalt solution here for more than a decade. The ProSizer has also been successfully applied in the quarrying environment, particularly as a wheeled
“The ProSizer has been out now for about 14 years. It’s a mature product for us,” Patrick Reaver, the product sales director for Astec, told Quarry.
The ProSizer – named for its “product sizer” application – incorporates a horizontal shaft impact (HSI) crusher and screen on a portable chassis and trailer. Traditionally, the ProSizer has been available in three models – the ProSizer 3100, 3600 and 4200. The average dimensions of each of these models is around 20.4m x 3.4m (length by width).
“Every ProSizer we’ve ever built is a closed circuit,” Reaver said. “It has a feeder, a crusher and a screen. Ideally, we screen the product first, especially if we’re talking about recycled asphalt. We take out as much of the minus product as we can, so we don’t over crush that product, then we send the overs back to the crusher and knock that last little bit of product back to the size that’s needed. Since we’re operating a closed circuit, everything that you put into that machine comes out as a sized product.
“Our main target with the ProSizer has always been recycled asphalt (RAP). RAP is sticky and tough to deal with, and it can often be slabby,” Reaver said. “To handle slabby material, we’ve developed an open conveyor design, so it can handle large slabby material. The overs conveyor can be operated remotely so if there’s a lot of reject material, you can remotely stop the feeder, swing the conveyor out, dump the reject material off to the side, swing the conveyor back in, turn the feeder back on and keep on going. It’s an easy way of getting reject material out of the system.
“We work hard to ensure our equipment performs well in tough environments and the ProSizer is no exception. Take the engine package for example,” Reaver said. “The ProSizer’s remote swing out radiator allows for easy maintenance and cleaning. The all-hydraulic drive also allows us to vary speeds. For example, on the impactor, we don’t want to over crush, we want to crush only as much as is needed to break the RAP back to its original size. Some equipment doesn’t break the product all the way down to the original sized rock, but we deliver a nice, coated rock at its original size. The ProSizer’s variable speed impactor allows us to dial in the requirement for the given conditions and makes sure we’re crushing it to the
Reaver added that the ProSizer can be programmed for different applications. “And there’s essentially an overload protection system that will slow the feeder down if necessary, so you don’t have to dig out the machine or end up with a product that’s
out of spec.”
In late 2019, Astec Australia incorporated multi-frequency screening technology into its ProSizer 3100 for the Australian market. It has been repurposed and resized for a range of recycling applications and has been adapted for universal roads access across all parts of the country. Australian transport regulations had been a limitation for earlier US-manufactured versions of the ProSizer.
“In the past, some of the road regulations that apply in Australia haven’t lent themselves to the easy transportation of the unit around the country,” Reaver explained. “So, in conjunction with Astec Australia, we came up with the product – still employing our multi-frequency technology – that offers really good capacities and meets the regulation and transport needs of the Australian market.”
The ProSizer 3100 with multi-frequency technology is suitable for sizing and screening products, including RAP, concrete, bricks, tiles, plasterboard, gypsum, limestone and glass. It is the first of the ProSizer range to include a twin-deck 4.2m x 1.5m multi-frequency screen in closed circuit with an Andreas 3136 HSI. The feed hopper offers 5m3 of capacity with a heavy-duty, sloped grizzly with 125mm openings.
The twin-deck screen can resize materials from 25mm down to 0.5mm, with two standard product conveyors and a returns conveyor that can be converted to a third product conveyor via radio remote control. The ProSizer’s carrier frame features a 533mm wide I-beam frame with an Australian-style kingpin, and hydraulic landing gear. The frame comprises a triple-axle assembly with 12 11R22.5 tyres, fenders and mud flaps, an air bag-type suspension with air brakes and an Australian standard lights package.
In recent years, Astec has sold several multi-frequency portable screens into the Australian market. One of these – a GT205MF – has successfully processed glass, plasterboard, gypsum, topsoil, crusher dust and manufactured sand. The first GT165MF arrived on Australian soil in the last quarter of 2019.
A particular advantage of multi-frequency screens is their ability to simultaneously screen both light and tough materials on separate decks.
Adam Gordon, Astec Australia’s national account manager for aggregates and mining, told Quarry that on a traditional twin-deck scalper, 600mm rock can be screened on the top deck and 20mm on the bottom. However, different masses of material require different forces to achieve the most efficient screening outcomes.
“Having the multi-frequency vibrators at the bottom, with five adjustable settings, means you can fine-tune them for the load over that section of the screen media, independent of the screenbox that’s taking care of the bigger material,” Gordon said. “With the benefits of the scalper on top, you can do flexible things with large rock there, while on the bottom you can get into those tougher 20mm and below applications, where it’s a finer or high moisture application. You can use the high frequency vibrators to better screen in those tough applications. So the multi-frequency bottom deck gives you a lot more throughput, efficiency and accuracy.”
Reaver explained that on Astec’s 35-tonne GT165MF, the standard top deck features a lower speed adjustable amplitude of about 950 revolutions per minute (rpm), an increased stroke rate of 6mm to almost 10mm, and hydraulic controls for variable angle operation.
The multi-frequency bottom deck has six independently-controlled exciters that can each apply an additional frequency of up to 4200 rpm to the screen media. This contributes to increased stratification and higher separation, with sizing down to as low as 400µm.
The multi-frequency screen on the ProSizer 3100 operates on similar specs and delivers the same high quality outcomes.
While the ProSizer plant was originally developed by Astec for the asphalt market and has been used for more than a decade by recycling and asphalt producers to separate bituminous asphalt content from cement, Reaver said the machine has been proven time and again to be a useful asset for quarrying operations, as well as mobile contractors.
“Our ProSizer series, as a whole, is a horizontal shaft impact crusher so, within limits, it will crush any material that a horizontal impact crusher will crush,” he said. “We’ve tried to make it extra friendly for the recycled asphalt market, but we do have units that crush virgin aggregates, sand and gravel, and concretes. In Peru, they’re even crushing seashells with it!
“We have a customer in Colombia who has three ProSizers crushing sand and gravel every day. That’s all they do. The customer is an asphalt producer, but they wanted to screen and process sand and gravel themselves, and now they do, with the ProSizer. So the ProSizer can act as a lone horizontal shaft impactor. It will crush.
“In the RAP environment we try not to over crush the product, we just want to break it down to its constituent elements for reuse in other roads. But, at the end of the day, the ProSizer is a horizontal shaft impactor that’s meant to crush, and it will crush virgin rock.”
The ProSizer 3100 with multi-frequency technology is now available to purchase from Astec Australia.