Metso sold more than 20 Vertimill stirred grinding mills with a combined 67 MW of installed power around the world in 2025, marking a record year for the Finnish supplier as mining companies sought technology that can cut energy use by up to 35 percent compared with conventional ball mills.
The sales surge highlights how quickly hard-rock miners are embracing energy-efficient comminution equipment to reduce both operating costs and greenhouse-gas emissions. It also underscores the competitive pressure on mine operators, especially in copper, gold, and iron ore, to comply with tightening climate regulations without sacrificing throughput.
Metso’s 2025 order book for stirred mills represented the biggest in the company’s history. According to industry coverage, many of the units are already being integrated into existing concentrators, demonstrating that plant managers increasingly favor bolt-on upgrades over wholesale redesigns when decarbonizing grinding circuits.
Mining publications attribute the record to a confluence of factors: heightened scrutiny of Scope 2 emissions, escalating electricity tariffs in many jurisdictions, and the maturity of stirred-milling technology, which is now proven in secondary, tertiary, fine, ultrafine, and regrind duties.
The core numbers tell the story. Engineering outlet Engineer Live reported that Metso “saw record sales of stirred mills in 2025 as mining customers opted for more energy-efficient grinding solutions” Engineer Live. Industry research site IM-Mining noted that Metso “sold over 20 Vertimill grinding mills with a combined installed power of 67 MW” and that the equipment “delivers up to 35% energy savings compared to conventional ball mills” IM-Mining.
Carbon impact calculations published by Aggregate Equipment Guide equate the emissions avoided through those energy savings to the annual footprint of roughly 20,200 people, based on a standard per-capita benchmark Aggregate Equipment Guide. That figure has resonated with investors and regulators tracking the mining sector’s decarbonization trajectory.
Beyond new greenfield projects, established concentrators are retrofitting existing lines. The specialist portal Geomechanics.io observed that “many existing concentrator plants are choosing to enhance operations with add-ons to incorporate stirred mill technologies” rather than replace an entire grinding circuit Geomechanics.io. The installed base now stretches across six continents and an array of ore types, suggesting the technology has moved from niche to mainstream.
Technology and Performance Profile
Vertimill®—Metso’s flagship gravity-induced mill—operates with a tall, slim housing and low occupational noise. Internal screw agitators keep grinding media in motion at lower tip speeds than a ball mill, slashing both power draw and wear-part consumption. The company says the 2025 units will displace roughly 36,000 kW of power demand when compared on a like-for-like basis with conventional circuits. When run for a typical 8,500 operating hours a year, that translates to more than 135,000 tonnes of CO₂ emissions avoided annually, a figure that aligns with external estimates.
Complementing Vertimill in Metso’s lineup are the HIGmill™ and Stirred Media Detritor (SMD) mills, which employ fluidized-bed and high-intensity configurations, respectively, for ultrafine duty and regrinds. The wider portfolio gives mine planners flexibility to combine multiple technologies—often adding a high-pressure grinding roll (HPGR) upstream and a fine-grinding stage downstream—to squeeze out incremental savings and recovery gains. For sulphide ores, Metso promotes pairing stirred mills with its Concorde Cell™ flotation unit to push valuable minerals into the concentrate stream at coarser grind sizes.
Why 2025 Was Different
Record sales did not happen in a vacuum. Commodity prices stayed robust through most of the year, giving miners budget headroom. Meanwhile, power grids in Latin America, Africa, and parts of Asia faced volatility, making energy-intensive ball-mill circuits both costlier and riskier. The International Council on Mining and Metals estimates that comminution can account for 3–4 percent of global electricity consumption; within a mine site it can reach 50 percent of total power draw. Cutting a third of that burden is a compelling value proposition in any market cycle.
Engineering groups also cite regulatory tailwinds. Several jurisdictions introduced or tightened carbon-pricing schemes in 2025, most notably Canada’s federal system and Chile’s planned expansion of its carbon tax. For multinationals with global footprints, every kilowatt saved cushions exposure to future levies.
Retrofit Wave Gathers Pace
A defining feature of 2025 was the number of brownfield projects. According to Geomechanics.io, process engineers are increasingly exploring hybrid circuits—keeping a primary SAG or ball mill but diverting a portion of the stream into a stirred-mill tower for secondary or tertiary grind. This strategy reduces capital expenditure and downtime and lets operators test performance before committing to broader rollouts.
Case studies published by suppliers and miners show energy savings can arrive in under 12 months, sometimes with coarser feed. Because stirred mills can deliver target particle size distributions with less over-grinding, downstream flotation stages often see improved recoveries, further enhancing the payback calculus.
Global Footprint and Service Support
Metso says its stirred-mill installed base now exceeds 1,000 units across hundreds of sites—a milestone built on five decades of research, prototype scaling, and field data. Its Plus portfolio bundles hardware with digital monitoring, remote diagnostics, and lifecycle services. Given that fine-grinding duty can be abrasive, real-time media-wear tracking and predictive maintenance have become selling points, especially for remote operations in Australia and northern Canada.
Suppliers’ challenge is to maintain global inventory of ceramic or stainless-steel grinding media and critical spare parts. To that end, Metso continues to expand regional service centers, supporting rebuilds and liner-change programs that many miners now outsource.
Environmental Accounting Gains Traction
Quantifying avoided emissions—expressed in people equivalents or tonnes of CO₂—has emerged as a marketing and financing lever. Sustainability-linked loans and green bonds often incorporate emissions-intensity metrics. For mine developers, the ability to demonstrate a 35 percent reduction in comminution power is increasingly material when negotiating offtake agreements with battery-metal or clean-tech customers, who face their own Scope 3 disclosure obligations.
Independent analysts caution, however, that total mine energy use also depends on upstream crushing, conveying, and downstream dewatering. Stirred mills are one piece of a broader puzzle that includes renewable energy procurement and process redesign.
Outlook and Implications
If 2025 set a high-water mark, two factors will shape whether the trend endures. First, grid decarbonization: as mines shift to wind, solar, or hydropower, the marginal carbon benefit of ultra-efficient equipment narrows, though the cost benefit persists. Second, ore hardness and complexity are rising as higher-grade deposits are depleted, pushing industry toward finer grind sizes that favor stirred-mill technology.
Market consultancies expect global demand for fine-grinding capacity to outpace new greenfield mine development, implying retrofits will dominate order books. Competitors to Metso, including FLSmidth and Swiss Tower Mills, are ramping production, but Metso’s 2025 performance positions it strongly to defend share.
For investors, the record sales underscore the tangible, quantifiable nature of mining’s energy-efficiency drive—an area where incremental technology can deliver immediate carbon and cost wins without waiting for breakthroughs in ore sorting, in-situ leaching, or autonomous haul fleets.
The 2025 surge in stirred-mill adoption signals a broader shift in how the mining industry views comminution: no longer a fixed energy sink but a variable that, when optimized, delivers fast, measurable gains. Whether measured in megawatt-hours saved, tonnes of CO₂ avoided, or the carbon footprint of 20,000-plus people, the numbers suggest that the once-niche tower mill now sits at the center of mining’s decarbonization strategy.
Sources
- https://www.engineerlive.com/content/2025-saw-record-sales-stirred-mills-metso
- https://im-mining.com/2026/01/13/metso-books-record-stirred-mill-sales-in-2025/
- https://www.aggregateequipmentguide.com/article/70090-record-year-for-metso-stirred-mills-as-mining-industry-opts-for-energy-efficient-comminution-technology
- https://www.geomechanics.io/news/article/metsos-record-2025-stirred-mill-sales-circuit-design-lessons-for-process-engineers
