Growing demand, complex geology and shifting global supply chains are pushing rare earth miners to rethink their front-end processing.
Demand for rare earths has doubled over the past decade, with the International Energy Agency forecasting that it could double again by 2050.
That demand is being driven by the central role rare earth elements (REE) play in the manufacture of clean energy technologies such as wind turbines, renewable batteries and electric vehicles. A renewed effort by Western nations to secure supply chains by sourcing REEs outside of China, which has increased export controls on several critical minerals, has further intensified the focus on diversified production.
Australia holds at least four per cent of the world’s rare earth reserves, positioning it strongly for growth. The US–Australia Critical Minerals Framework added further momentum to the development of exploration, production and processing capabilities across the country.
However, accessing REEs is not always straightforward.
While traditional processing flowsheets for REEs rely heavily on multiple stages of crushing, screening and grinding, many operations are now investigating alternative front-end strategies that reduce capital intensity, simplify material handling, and improve mine-to-mill efficiency.
One such approach is in-pit sizing – the use of a Sizer within or near the mining face to condition ore before it leaves the pit.
For rare earth projects, which often occur in complex geological settings with variable textures, weathered profiles and highly abrasive gangue minerals, in-pit sizing offers compelling advantages. These include reducing haulage requirements, stabilising feed to downstream plants and minimising the number of material-transfer points, each of which can materially reduce operating expenditure.
MMD Group, a leading provider of mineral processing technologies for the mining, quarrying and recycling sectors, is helping REE miners explore this approach.
Established in 1978 to serve the underground UK coal industry, MMD began by designing and manufacturing inline breakers. Early in its history, the company invented and patented the twin-shaft Mineral Sizer, launching the first 500 Series model in 1980. These machines were quickly adopted throughout the UK before spreading globally over the following decades.
Today, the company produces a wide range of Sizers, Sizer stations and feeders suited to varied operating conditions.
A Sizer-first alternative
According to MMD Australia West director Morné Coetzee, conventional rare earth comminution circuits in Australia tend to follow a familiar pattern: primary jaw crushers, secondary cone crushers and, depending on the desired product size, tertiary crushing or milling.
While well understood, she said, these circuits require significant structural and civil works, multiple conveyors and transfer stations, and fixed plant locations with limited flexibility. They also generate high levels of dust and fines and demand substantial power in downstream milling.
“Rare earth deposits in Australia, such as monazite- and bastnäsite-dominated systems, often contain a mix of clays, weathered saprolite and harder fresh rock,” Coetzee told Australian Mining.
“In traditional crushers, this variability drives fluctuating performance, unstable throughput and inconsistent product size.”
In-pit sizing provides an alternative by conditioning ore to a consistent, conveyable size early in the material-handling chain.
Selecting the right Sizer begins with evaluating the material properties of the ore being mined and loaded.
Coetzee said REE deposits often present unique challenges because of their complex geology.
“REE deposits, especially lateritic and weathered granitoid-hosted ore bodies, may contain fines and clays that become plastic under moisture,” she said. “Moisture fluctuations, especially in Australian climates, affect material cohesion, stickiness and throughput reliability. Wet or sticky ore can bind traditional crushing equipment, reducing production. A Sizer is designed to process wet and sticky material with a self-cleaning design.
“REE mine designs also have many satellite pits, so equipment still needs to process effectively while remaining mobile. The MMD equipment is perfect for this application.”
MMD works closely with its customers to gather engineering, operational and material-specific data to determine the appropriate Sizer model and configuration.
“It involves identifying the physical properties of the material including, but not limited to, size distribution, MPa [megapascal], abrasion index, moisture content, bulk density, plasticity, oversize frequency and contaminants,” Coetzee said.
“We then consider throughput and production targets, including peak surges and feed consistency. The required product size, combined with the material properties, determines the Sizer model, tooth configuration and speed.
“Other considerations include upstream and downstream processes such as interface heights, discharge angles and transfer points. The initial evaluation also factors in site integration requirements, including footprint restrictions, structural limitations, energy supply and environmental constraints.”
Whether a project is brownfield or greenfield also influences the commissioning process.
“For greenfields, our engineering team can assist with any design, suggesting the best upstream and downstream processing solutions, including feed methodology and transfer point designs,” Coetzee said.
“Brownfields have other considerations. After an on-site evaluation, we determine the best replacement methodology and assess constraints such as pit location, feed consistency, structural limits, footprint, equipment mobility and environmental factors.”
MMD Sizers are available with a range of tooth configurations and purpose-designed gearboxes that cater to a wide spectrum of project needs. But REE operations often require additional customisation.
“While many customers adopt standard options, rare earth operations tend to require more specific modification – especially for tooth design and wear linings – due to clay content and abrasiveness,” Coetzee said.
Customisation may be needed when mineralogy involves unusually abrasive components that requires bespoke wear packages, or when oversize frequency or lump shape is atypical and calls for modified tooth height, pitch or breaker bar arrangements. Coetzee said Sizers deliver an advantage over cone or impact crushers when dealing with the sticky or plastic clays common in REE environments, with custom options providing further adaptability.
“Sizers are well-suited to high-moisture environments, and selecting the right tooth configuration depends on the material’s moisture characteristics,” she said.
Other site-specific factors include power-train or footprint restrictions, unusual loading angles and non-standard hopper integration.
More than machinery
With offices and workshop facilities in Brisbane, Perth the Hunter Valley and Mackay, MMD maintains extensive spare-part holdings to support its customers.
“Our technicians are all long-term employees who intimately understand the equipment. We offer service contracts and take pride in our responsiveness,” Coetzee said.
“On-site performance monitoring and optimisation, wear-part supply and planning, operator training, maintenance support and lifecycle upgrades are all key elements of the service we provide.”
With many Australian REE projects still refining their geometallurgical models, early-stage decisions remain critical. To help de-risk those early commitments, MMD offers flexible commercial pathways that allow customers to validate performance and build confidence before committing to a capital purchase.
With demand for rare earths only set to increase, Australian REE operations can rest assured that MMD Group has a legacy of innovation and implementation that can help unlock rare earths opportunities in all kinds of environments.
Read more: Top five rare earths projects to watch in 2026
This feature appears in the February issue of Australian Mining magazine.