The traditional wet mill is a relic of an era when water was infinite and energy was cheap. That era is over.
The wet mill is dying. It just doesn’t know it yet. For over a century, the mining industry has operated on a simple, brutal logic: drown the ore in water, hammer it with thousands of tons of steel balls, and hope the energy bill doesn’t bankrupt the operation. It was a messy, inefficient process that worked because nobody was counting the carbon: or the drops of water.
But as we sit here in March 2026, the math has changed. The decarbonization roadmap isn’t a suggestion anymore; it’s a stranglehold. With the recent announcement of the exclusive partnership between Metso and Loesche to scale Vertical Roller Mill (VRM) technology for the mining sector, we aren’t just looking at a new piece of kit. We are witnessing the pivot point where “Green Steel” stops being a marketing slogan and starts becoming a metallurgical reality.
The move to dry grinding is the single most important technical shift in mineral processing this decade. If you’re still planning a project around traditional SAG and ball mills, you’re essentially building a museum.
The Problem with the Old Guard: SAG and Ball Mills
Traditional comminution: the process of crushing and grinding ore: is the industry’s biggest secret shame. It consumes roughly 3% to 4% of all global electricity. In a typical mine, the grinding circuit accounts for over 50% of the entire site’s energy consumption. Most of that energy isn’t even used to break the rock; it’s lost as heat and noise, or used to tumble massive loads of steel balls that eventually wear down and need replacing.
Then there’s the water. Wet mills require a staggering amount of it to create the slurry needed for processing. In regions like the Vicuña District or the high Andes of Peru and Chile, water isn’t just an operating cost: it’s a geopolitical landmine. You can’t run a traditional mill without a massive tailings dam, which is essentially a multi-billion-dollar liability waiting to happen.
Caption: Traditional SAG and ball mills represent an energy-intensive legacy that 2026 decarbonization targets can no longer accommodate.
The Metso-Loesche Partnership: Why Now?
The partnership between Metso and Loesche, finalized this month, is a tactical masterstroke. Loesche has been the king of VRM technology in the cement industry for decades, with over 2,400 operational references. They know how to grind material dry, and they know how to do it at scale. Metso, meanwhile, owns the mining footprint.
By combining Loesche’s dry-grinding IP with Metso’s mineral processing expertise, they have solved the “reliability” excuse that miners have used for years to avoid switching. The industry has always been terrified of being the “first” to try something new. Now, they don’t have to be. The tech is proven; it’s just being repurposed for the brutal demands of iron ore and copper.
The Brutal Numbers: 40% Savings is Not a Typo
The technical specs of the VRM pivot are enough to make any CFO sweat. We aren’t talking about marginal 2% or 3% gains. We are talking about a fundamental shift in the cost curve.
- Energy Savings: The Metso-Loesche VRM systems are delivering up to 41% energy savings compared to conventional wet grinding. In a world where power prices are volatile and carbon taxes are looming, that is the difference between a profitable Tier 1 asset and a stranded one.
- Zero Water: As the name implies, dry grinding doesn’t need water. It uses a bed of material and high-pressure rollers to achieve liberation. For projects in Australia or the Atacama, this removes the need for massive desalination plants and the associated energy-intensive pumping costs.
- No Grinding Media: Forget the steel balls. VRMs use the ore itself and the pressure of the rollers. This eliminates the carbon footprint of manufacturing and transporting thousands of tons of steel grinding media to remote sites.
Modern dry grinding facilities represent a shift toward modular, water-independent mineral extraction.
The Green Steel Connection: DRI and Hydrogen
Why is this happening now? Because the steel industry is in a panic. The transition to Green Steel requires a shift from blast furnaces to Direct Reduced Iron (DRI) processes fueled by green hydrogen.
But here’s the kicker: DRI plants are picky eaters. They require high-grade iron ore, typically with an Fe content of over 67%. Achieving that grade requires superior mineral liberation: getting the iron away from the waste rock with surgical precision.
Wet mills produce a wide distribution of particle sizes, often “over-grinding” the material into slimes that are hard to recover. VRM technology offers a much steeper particle size distribution. You get exactly the size you want, which leads to better downstream separation and higher-grade concentrates. Without the precision of dry grinding, the hydrogen-based steel revolution simply doesn’t have the “fuel” it needs to scale.
The 2026 Copper Roadmap: A Secondary Benefit
While the headlines are focused on iron ore and steel, the implications for copper are just as massive. As we’ve discussed in our Copper Processing 101 guide, the industry is struggling with declining ore grades. To get the same amount of copper, you have to grind twice as much rock as you did twenty years ago.
If you try to meet the “Green Transition” copper demand using 1950s wet-milling technology, the energy consumption would be astronomical. The Metso-Loesche VRM pivot provides a blueprint for the copper mines of 2026 and beyond. By moving to dry grinding, copper miners can handle lower grades without doubling their energy bills or their water consumption.
Engineers are increasingly looking to VRM technology to solve the energy-grade paradox in the copper sector.
The ESG Reality Check
Let’s be honest: ESG has often been treated as a compliance checkbox. But in 2026, it’s becoming a physical constraint on production. You can’t get a social license to build a new tailings dam in most jurisdictions anymore. You can’t outbid local communities for water in a drought-stricken province.
The “Death of the Wet Mill” isn’t just about efficiency; it’s about survival. A dry-grinding circuit eliminates the need for a traditional wet tailings dam. Instead, you get dry-stacked tailings that are safer, more stable, and have a significantly smaller footprint. It’s the ultimate “de-risking” strategy for junior miners and majors alike.
We’ve seen recent moves in the industry, like USA Rare Earth’s consolidation of the Round Top project, where the focus is increasingly on sustainable, domestic processing. The technology used to grind that ore will be the deciding factor in whether those projects meet their ESG targets.
The Watershed Moment
The Metso-Loesche partnership is the signal that the “early adopter” phase is over. When the biggest names in the business commit to a technology, the rest of the industry follows: or gets left behind.
We are moving toward a mining environment that is:
- Water-Agnostic: Operating in deserts without massive pipelines.
- Energy-Efficient: Cutting the single largest power draw on the site by nearly half.
- Carbon-Conscious: Eliminating the hidden carbon in steel grinding balls and reducing the total site footprint.
It’s a nasty realization for those who have spent their careers optimizing wet circuits, but the efficiency gap is now too large to ignore. A 40% energy saving isn’t a “nice-to-have.” It’s a competitive weapon.
While heavy equipment does the lifting, the real battle for sustainability is won in the grinding circuit.
What Happens Next?
The next 18 months will be a scramble. As the Metso-Loesche VRM units begin to roll out across Tier 1 iron ore projects in the Pilbara and Brazil, the data will likely confirm what the cement industry has known for years: dry is better.
Expect to see a massive wave of retrofits. The CAPEX for a VRM system isn’t small, but the OPEX savings: specifically on power and water: pay for the transition faster than almost any other upgrade in the mill.
The wet mill isn’t going to vanish overnight. There are thousands of them currently spinning, and they will continue to spin until the cost of carbon or the lack of water forces them to stop. But for any new project hitting a feasibility study in 2026, the choice is clear. You either pivot to dry grinding, or you explain to your investors why you’re choosing to waste 40% of your energy.
That’s a needle that’s almost impossible to thread. Welcome to the era of the dry mill.
