Astec are screening the green transformation

Astec and mining contractor Salmon NC have developed a bespoke waste retreatment screening solution for a major nickel miner in New Caledonia. And Astec’s screening offerings don’t stop there.

As we near a net-zero reality, there is an increasing need for more materials to develop the necessary green technologies.

Renewable energy sources such as wind and solar require up to five times more copper than comparable non-renewable technologies, while the World Economic Forum believes demand for lithium carbonate equivalent (LCE) could surpass three million tonnes by 2030. The world produced 540,000 tonnes of LCE in 2021.

LCE, derived from lithium raw material, spodumene concentrate, is a critical material in renewable batteries used in electric vehicles (EVs).

While primary production will remain key, as mineral demand increases into the future amid growing decarbonisation, mining companies will need to be more creative in how they commercialise their material.

A nickel mine in New Caledonia, some 1200km east of Queensland’s Sunshine Coast, is doing just that.

SLN (Société Le Nickel), which operates a nickel smelter and several mines on the island, has established a unique method for recycling nickel slag – a major by-product of the nickel refining process – with the assistance of mining contractor Salmon NC and leading mining equipment supplier Astec.

The recycled nickel slag is sold into a variety of markets, including the abrasives industry in the US, where it is used as a sandblasting medium.

While heavy equipment hire has always been Salmon NC’s bread and butter, chief executive officer Chris Salmon turned to Astec when it came to finding the specialty equipment needed to re-process nickel slag.

“I’d known Astec from a past life when I was involved in basalt quarrying, and they’ve always come really well referenced,” Salmon told Australian Mining. “I’d reached out to some industry contacts explaining what I was trying to achieve and Astec’s high-frequency screens were mentioned a couple of times by people I trusted.”

Salmon got in touch with Shaun Quinn, Astec’s senior account manager, materials solutions – northern region, and before too long an Astec GT2612V high-frequency screen had made its way to New Caledonia.

“Shaun was very helpful in identifying the type of unit we wanted,” Salmon said. “We were looking at fixed and tracked solutions, but we chose the tracked machine because we needed mobility around how we were building our stockpiles.

“We’ve been impressed by Astec’s after-sales support, too. We need that support given we’re quite isolated in New Caledonia.”

The Astec GT2612V high-frequency screen has 10 vibrators that directly-induce vibration into the bed of material at between 3600–4200 revolutions per minute (RPM), to ensure increased probability of stratification and material separation.

A unique media rotary tensioning system used on the high-frequency screens means operators of the GT2612V can quickly and efficiently change screen media when switching between applications, supporting a more efficient and productive operation.

And while the GT2612V is powerful, it’s also versatile.

“The screen itself is made up of four six-by-six-foot panels, with the first panels on each deck having three independently adjustable vibrators,” Quinn told Australian Mining.

“The screen operates between 28–43° of inclination, with the vibrators running at up to 4200RPM with as much as 2mm of stroke, so you can ensure they are optimised for each application.   

“On average, these machines can induce around 10g of force into the material if you’re running them flat out, but you can also de-tune individual sections accordingly to stop ‘pop-corning’, or the bouncing of the raw material, from occurring.”

The GT2612V was delivered and commissioned to New Caledonia in November 2022 and has been processing large volumes of material ever since.

The process involves feeding stockpiled nickel slag through a static grid to remove larger agglomerates before it reaches the high-frequency screen, which then refines the product into a usable material.

“Minus-50mm material is sent to the high-frequency screen, which separates anything bigger than 4mm,” Quinn said. “Anything smaller is finished product in this application.”

The GT2612V’s adjustability came in handy when the Salmon NC team discovered the nickel slag material was more abrasive than anticipated.

“This briefly caused some operational issues for us,” Salmon said.

“But the Astec support team was fantastic. They helped us make tweaks and adjustments to settings and flow rates, and alter the way we were processing the material to best deal with its abrasive nature.

“Now we’re getting the best out of the machine itself, and the best operational efficiency.”

Since the six-foot-wide GT2612V arrived in New Caledonia in November 2022, Astec has developed a larger eight-foot-wide, 18-foot-long high-frequency screen. Quinn said the new model, launched at CONEXPO in Las Vegas in mid-March, enables greater capacity.

But when finding the right screen for a customer and for a particular application, bigger is not necessarily better.

“It comes down to what customers are looking for,” Quinn said. “If they don’t have room to set up a fixed plant, and if they want something that’s mobile and able to be utilised in a tighter, confined space – as with Salmon NC and the nickel slag application – the tracked screen is ideal.

“But if you’ve got a bit more room, and you’re going to go down the path of investing in a fixed plant, Astec’s new eight-foot-wide screen is going to be something to consider.

“The bottom line is the technology works and, with its multiple tuning options, we will ensure screens are optimised to suit any application and material.”

Quinn said that just a few weeks on from CONEXPO, Astec had already sold two of the eight-foot-wide screens into the local market.

Astec can also build a ‘hybrid machine’ for its customers.

“The offshoot of these machines is our multi-frequency screen,” Quinn said.

“These incorporate a conventional screening action throughout the whole screen but also utilise our high-frequency technology on the bottom deck.

“The high-frequency action provides additional vibration directly into the media on the bottom deck which helps with separation in finer material or wetter applications.“

Whether it’s the GT2612V, the new eight-foot-wide screen, the multi-frequency option, or any other bespoke screening solution, Astec has a solution to suit any mineral processing application. Astec’s screens are proven in repurposing mine waste for a major nickel miner in New Caledonia, and many other Australian mining companies and contractors can attest to the supplier’s capability.

And as demand for minerals increases amid growing decarbonisation, Astec’s innovative technologies will continue to help its customers find new markets for their products. In this green transformation, Astec’s ongoing role as a key industry partner is assured.

This feature also appears in the May edition of Australian Mining.

Australian Mining.

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