Metso’s Dry Flowsheet Bet: What the Evidence Actually Shows

Comminution, the crushing and grinding that reduces ore to a size where valuable minerals can be separated, already consumes up to around 70% of the energy in a conventional processing circuit. The industry has known this for decades. What it has mostly done about it is tinker at the edges.

Then on 10 September 2026, Metso ran its first global virtual Summit and put six technology launches on the table in a single session, each one aimed at moving that number. The density of that launch activity, not the event branding, is what makes this worth a closer look. When a major original equipment manufacturer (OEM) fires across crushing, screening, grinding, flotation, and digital in one sitting, it is signalling where competitive pressure in the sector now sits: dry grinding, fine dry classification, coarse particle flotation, and digital integration, all pushed by the same four forces of energy cost, water scarcity, tailings regulation, and ESG scrutiny.

This analysis walks through what each technology actually claims, where those claims rest on independent evidence and where they rest only on manufacturer data, and the questions a mining operator or procurement team should ask before any purchasing conversation begins. Metso is not alone in this race; FLSmidth and Weir Minerals are pushing toward the same destination, which changes how you should read any single launch.

Six launches, one thesis: what Metso put on the table at its inaugural Summit

The Summit ran as a studio-produced virtual event across two sessions, complete with expert interviews and three-dimensional technology models. Strip away the format, and what registers is the breadth. Five technology categories, launched at once, is not a product catalogue update. It is a flowsheet strategy.

Metso president and chief executive Sami Takaluoma framed the launches as an attempt to redefine flowsheet performance while cutting environmental footprint. Read that alongside the actual product mix, and the strategic offer becomes clear: this is an integrated dry-or-lower-water flowsheet pitch, not a set of standalone upgrades.

Crushing capacity and site adaptability: Primarok, Optirok, and Durarok

The three crushers split cleanly by application. Primarok is a gyratory unit pitched at high-volume hard-rock duty, with one model rated up to 20,000 t/h. Optirok, a compact jaw crusher at roughly 1,200-2,500 t/h, targets space-constrained brownfield and modular sites. Durarok is a sizer built for sticky, wet material, running approximately 1,500-6,000 t/h depending on feed.

These first appeared in June 2026, ahead of the Summit. Beyond capacity ranges and Metso’s own materials, hard independent numbers on power draw, reduction ratio, and specific energy are not yet public. For an evaluator, that means the crushers are the most conventionally specified tier here, but still short of third-party benchmarking.

The energy and water technologies: VRM, GFF screens, and coarse particle flotation

The three technologies carrying explicit energy and water claims are where the analytical weight sits, because their numbers can be stress-tested. The GFF Series screens deliver dry classification down to 0.3 mm without process water, using hybrid flip-flow screening to handle fine, sticky material that conventional screens blind on. The Metso Loesche VRM claims the headline energy figure. The new coarse particle flotation technology is the least documented of the launches, with no independent deployment evidence identified, and that gap runs through the rest of this analysis.

The 40% energy claim and the evidence behind it

The number to interrogate is the VRM’s. Metso’s dry grinding brochure claims up to 40% energy savings when grinding from F100 below 150 mm to P80 below 20 microns. International Mining repeated the same figure in March 2026, but repetition in trade press is not independent testing. No named analyst firm, research institution, or independent lab has validated the Metso-Loesche-specific figure.

That is not the same as saying the claim is baseless. The closest third-party evidence comes from a paper by Gerold presented at Comminution ’25, which modelled a VRM-HydroFloat circuit against a conventional SAG-ball (SAB) arrangement.

A VRM-HydroFloat circuit achieved a 42% reduction in total energy consumption and roughly a 24% reduction in overall plant water consumption versus a conventional SAB circuit, when switching primary grinding from wet milling and separation to dry. Source: Gerold, “Extending the dry processing route,” Comminution ’25.

Here is the important distinction. Gerold’s study was not branded as the Metso-Loesche VRM. It supports the plausible magnitude of VRM-enabled savings; it does not validate Metso’s specific product. So a procurement team asking for independent evidence is not starting from zero, but it is not finished either. The right ask is whether Metso can produce site-specific testwork at the scale of Gerold’s circuit modelling.

The deeper issue is the gap between unit-operation metrics and flowsheet-level metrics. A VRM might genuinely save energy in isolation while the surrounding circuit gives some of it back. Ausenco has cautioned that dry classification can itself be energy-intensive enough to erode the gains from an otherwise efficient dry comminution circuit. The 40% figure means little until you know whether it describes the mill alone or the whole plant.

Before accepting the headline, an operator should ask three things:

• Is the claimed saving a unit-operation figure or a whole-of-plant figure?
• Is there site-specific testwork available for the ore in question, not just a brochure number?
• Are the downstream separation processes also dry or coarse-concentrating, or does wet beneficiation follow?

That third question matters more than it first appears, and it is where the industry context comes in.

Why dry and coarse is the direction the whole industry is heading

Step back from Metso’s specific numbers, and the direction they are pushing is not proprietary. It is where the whole sector is converging, and that changes how you should read any single OEM’s launch.

The structural reason is that comminution consumes up to around 70% of a conventional circuit’s energy. That is not a marketing talking point; it is why crushing, grinding, and classification are the battleground for competitive OEM investment. Any credible efficiency gain has to come from this part of the flowsheet.

Comminution’s dominant share of circuit energy stems directly from how particle size decisions cascade through every downstream separation stage; grinding finer than necessary to guarantee liberation is where most of that energy disappears, which is precisely why coarse flotation research targets the P80 rather than the mill itself.

The scale of comminution’s energy burden is well established in peer-reviewed comminution energy research, which documents grinding alone accounting for 50-70% of total mineral processing energy consumption, giving any credible efficiency intervention in this part of the flowsheet outsized significance for operating cost and carbon footprint.

Four pressures are driving the shift, and none of them is softening:

• Energy cost, given comminution’s dominant share of circuit consumption
• Water scarcity, now a hard operating constraint in many jurisdictions
• Tailings regulation, tightening around storage facility stability and footprint
• ESG scrutiny, raising the bar on water use and waste across permitting environments

The competitive field confirms the direction. FLSmidth‘s Barthold argues that dry grinding directly reduces water use, but only when downstream processing is also dry or coarse-concentrating. Weir Minerals promotes air classification as a dry alternative and advocates coarse particle flotation plus improved hydrocyclones to cut over-grinding. Ausenco’s Foggiatto notes that experts surveyed see HPGR-based dry grinding as the most energy-efficient circuit type available. When three or more OEMs and independent researchers point the same way, the technology direction itself looks durable rather than one company’s gamble.

The research on coarse flotation reinforces it. Duffy et al. estimate that flotation at 0.3 mm rather than 0.1 mm could cut comminution energy by roughly 30-50%, because less fine grinding is needed. Lane et al. (CEEC) describe coarse particle flotation being installed either directly after grinding or as a scavenger, both aimed at allowing a coarser P80 and lower grinding energy.

Coarse particle flotation is reshaping concentrator design not just by recovering at a coarser P80, but by enabling a reclassification of the entire flowsheet around a higher target grind size, which is the lever that unlocks the comminution energy reductions Duffy et al. estimate at 30-50%.

The condition that determines whether dry-route gains are real

There is a catch that decides whether any of these water savings survive to the bottom line. If dry grinding is followed by wet beneficiation downstream, the water you saved upstream is largely added back later. FLSmidth’s Barthold frames this directly: net plant water consumption barely moves unless the whole route stays dry.

Dry separation technology applied downstream of a VRM is the condition that determines whether whole-plant water savings survive the flowsheet, because replacing wet grinding without also replacing wet beneficiation simply shifts the water balance rather than reducing it.

This is exactly the condition Metso’s coarse particle flotation is designed to address. Paired with the VRM and the GFF screens, it lets separation happen without reintroducing water. The whole-of-flowsheet logic, not any single machine, is the actual offer, and it is why the launches came together rather than one at a time.

How to stress-test OEM launch claims before procurement decisions

None of this means you should be sceptical of the technologies. It means you should be equipped to separate credible claims from marketing headlines, using the same frameworks Ausenco, FLSmidth, Weir Minerals, and independent researchers already apply.

The primary due-diligence question is the flowsheet-versus-unit-operation one. Ausenco’s position is that energy and water savings from dry grinding must be judged at circuit level, because a saving in the mill can be undone if downstream separation stays wet. Ask whether the cited number describes the equipment in isolation or the plant as a whole.

Auxiliary system risk is the second trap. Dry classification can be energy-intensive, and the net circuit gain depends on whether that auxiliary consumption is captured in the headline figure or quietly left out of it.

Independent precedent is the benchmarking tool. Gerold’s VRM-HydroFloat result gives you a reference point: a 42% energy reduction and roughly 24% water reduction against SAB. A new VRM claim in that range is plausible; one well above it should invite harder questions.

“Efficiency claims should be tested against whether the technology materially changes the point of separation, rather than simply substituting like-for-like equipment.” Boylston (Metso), quoted in Ausenco’s “The Future of SAG Mills,” June 2024.

Boylston’s formulation is the sharpest filter of the lot. Applied to any OEM launch, it reduces to four sequential questions:

1. Is the claim a unit-operation figure or a circuit-level figure?
2. Is the evidence independent, or manufacturer-sourced only?
3. Is auxiliary system energy, especially dry classification, captured in the number?
4. Does the technology change the point of separation, or just swap in like-for-like equipment?

One caution on evidence quality. Some widely circulated coarse gangue rejection figures, including claims of 30-50% ball-mill energy reduction, tailings 2-3 times coarser, and around 40% less flotation capacity, are unverified in the available research base and should be treated with care rather than cited as fact.

Run the Metso launches through those four questions, and they sort cleanly. The VRM has independent contextual support but no product-specific testwork. The crushers have capacity specs but no independent performance data. The coarse particle flotation technology has neither yet. That sorting is where the burden of proof should sit before any capital is committed, and the framework works on the next OEM pitch just as well.

What Metso’s Summit signals for equipment strategy in the next procurement cycle

The clearest read on the Summit is this: Metso is assembling an integrated dry-or-lower-water flowsheet, and the sector consensus says that direction is right. The open question is not whether dry and coarse is the destination. It is whether Metso’s specific implementations deliver at commercial scale.

That question resolves over the next 12-24 months, and three evidence gaps are the ones to watch:

• Strongest independent contextual support: the VRM, backed by Gerold’s third-party circuit result, and the GFF Series, whose specifications are confirmed
• Awaiting independent site testwork: the crusher performance data beyond capacity ranges, and any commercial deployment data for the coarse particle flotation technology
• Unverified and flagged: the CEEC-linked coarse gangue rejection figures, which the research base does not confirm

The crusher range is the most procurement-ready tier. Capacity is specified, the design intent is relatively conventional, and near-term evaluation is tractable. The VRM and CPF sit further out, dependent on testwork and deployment data that does not yet exist publicly.

Emerging crushing technology across the sector is increasingly evaluated on specific energy and reduction ratio rather than throughput capacity alone, a shift in procurement criteria that explains why Metso’s crusher launches are the most near-term actionable tier in the Summit portfolio despite having the thinnest independent performance data.

For an operator planning the next major comminution investment, the Summit marks the point where integrated dry-flowsheet capability shifted from a differentiating offer toward a threshold expectation, one FLSmidth and Weir Minerals are chasing too. Within five to ten years it is likely to be baseline rather than an edge. Waiting for every evidence gap to close before starting testwork is itself a strategic risk. The smarter move is to demand independent testwork now on the VRM, monitor the CPF deployments as they land, and move on the crushers where the evidence is already solid enough.

This article is for informational purposes only and should not be considered financial advice. Investors should conduct their own research and consult with financial professionals before making investment decisions. Financial projections and performance claims are subject to market conditions and various risk factors, and manufacturer figures cited here await independent validation.