Mining Magazine article, 27 Nov 25

New technology advances fine particle recovery

by Prealene Khera November 27, 2025

An update to an advanced, gravity-based separation device, driven by the University of Newcastle, aims to improve fine particle recovery and support critical mineral extraction.

In the world of mineral processing, change sometimes comes in the form of precision engineering rather than sweeping reinvention.

And at the University of Newcastle, a significant advancement guided by Professor Kevin Galvin is reshaping how the mining sector recovers fine particles – materials that have long slipped through the grasp of traditional separation methods.

At the centre of this development is a mechanical rake. While it moves slowly, almost imperceptibly, through the suspension at the base of the reflux classifier, its impact on separation efficiency could be profound.

The reflux classifier is a separation device that uses upward-flowing water and a series of inclined channels to sort particles based on their density.

Denser, valuable particles settle downward and are collected, while lighter, less useful material is lifted out and removed.

It has already proven itself as a more compact and efficient alternative to traditional gravity-based systems.

A new version of the technology is now being developed to address one of the industry’s most persistent challenges: separating ultra-fine particles with high precision.

The addition of a mechanical rake is central to this evolution.

Galvin sees the function of the new rake as both subtle and significant, enhancing how the reflux classifier performs under increasingly demanding mineral processing conditions.

As it turns slowly through the lower section of the device, the rake helps create a stable, dense fluidised bed of particles.

“The slow-moving rake makes the fluidised suspension of particles behave much more like a dense liquid,” Galvin told Mining.

“We know that when a particle is placed into a fluid that is denser than the particle, the particle is propelled upwards by the buoyancy, an effect attributed to Archimedes.”

This added buoyancy improves separation, allowing the system to recover finer, denser mineral particles that would otherwise be lost to tailings. These gains are particularly relevant for critical minerals such as tin and manganese, which often occur in ultra-fine form and are vital to emerging technologies.

“The older technologies were unsuccessful in recovering the finer particles,” Galvin said.

“Therefore, the future of the industry depends on our ability to process much finer particles.”

To accelerate the development and scaling of the rake-enhanced system, Galvin’s team has secured more than $1.5 million through the Australian Economic Accelerator (AEA) Innovation grant program, with matched support from the project’s industry partner and the University of Newcastle.

The grant enables a full-scale prototype to be designed, built and tested over two years.

“We have already proven the technology works at a small scale, but it is well known that the next phase is often the most difficult,” Galvin said. “[This] funding helps to de-risk the up-scaling.”

The technology also offers operators a rare level of control. The system allows for a specific density cut-off, enabling users to prioritise either higher recovery or higher concentrate grade depending on operational needs.

“This level of control is often not available in other technologies,” Galvin said.

That flexibility, combined with high separation performance in a compact footprint, makes the system particularly well-suited for modern mining environments, where orebodies are becoming more complex and expectations around environmental performance are growing.

The rake-equipped reflux classifier is part of a broader platform of separation technologies being developed by Galvin and the industry partner.

These developments reflect a shift in how the industry approaches mineral processing, prioritising efficiency, control and responsiveness to more complex resource challenges.

And at the centre of this industry shift sits a slow-turning rake that is helping mining operations recover greater levels of value with a reduced environmental footprint.