Metso to supply VRM dry grinding technology to Jerritt Canyon

Metso has secured an approximately €9 million order to deliver its Metso Loesche Vertical Roller Mill (VRM) dry grinding technology and associated auxiliary equipment to First Majestic Silver Corp. The equipment will support the restart project of the historic Jerritt Canyon Gold Mine in Nevada, USA. Booked in the Minerals segment's third quarter of 2026, the order marks a significant milestone in introducing the innovative Metso Loesche VRM technology to the broader mining industry for highly energy-efficient comminution.

Seamless integration and superior drying performance
Delivered in partnership with Loesche, the comprehensive package includes the Metso Loesche VRM, a baghouse filter, a process fan, a hot gas generator, and extensive engineering support to ensure safe and reliable implementation. At the Jerritt Canyon site, the VRM system will be utilized to grind and dry the mineral material feeding the mine’s existing roaster circuit. According to Stefan Baaken, Managing Director of Loesche Australia, the technology offers outstanding energy efficiency combined with superior drying capabilities, providing a distinct advantage over competing comminution methods. Furthermore, the system's compact footprint makes it highly suitable for integration into existing brownfield processing plants without requiring massive structural overhauls.

Additional Context: Thermodynamics of air-swept dry grinding and roaster feed
This section details the physical principles of vertical roller mills and pyrometallurgical feed preparation not included in the original press release.

In mineral processing, comminution (crushing and grinding) is notoriously energy-intensive. Traditional tumbling mills, such as Semi-Autogenous Grinding (SAG) and ball mills, rely on cascading steel media and water to break down ore into a wet slurry. This wet process is highly inefficient for downstream pyrometallurgical operations, such as the roaster circuit at Jerritt Canyon. If a wet slurry is fed into a roaster, a massive amount of thermal energy is wasted simply vaporizing the water content before the actual chemical roasting of the ore can begin.

The Vertical Roller Mill (VRM) fundamentally alters this flowsheet by utilizing dry, air-swept grinding. In a VRM, hydraulic rollers exert immense localized pressure on a rotating grinding bed, fracturing the ore through pure compression and shear forces, which is mechanically far more efficient than the random impacts in a tumbling mill. Simultaneously, the hot gas generator introduces high-velocity thermal air into the mill. This integrated airstream instantly evaporates residual moisture in the ore, while pneumatically lifting the finely ground particles toward a dynamic classifier at the top of the mill. Properly sized particles are carried out to the baghouse filter, while oversized particles drop back onto the table for further grinding. This single-unit consolidation of grinding, drying, and classifying drastically reduces overall energy consumption and provides an optimal, bone-dry feed for the roaster.

Edited by an industrial journalist, Lekshman Ramdas, with AI assistance.

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