CRGM Series · Ring Roller Mill with Multi-Head Classifier
Multiple classifier rotors working in parallel unlock the full grinding capacity of the mill at 800–2500 mesh — sharper cut, narrower particle size distribution, and lower energy per ton for non-metallic minerals.
Clarify the term first
Many buyers confuse the two. On this page, multi-head (multi-head classifier) refers to the classifier on top of the mill: instead of one rotor (impeller), several rotors are connected in parallel inside one classifier head. The grinding chamber below — turntable, rollers and rings — remains one identical set.
One impeller on the classifier shaft. The impeller's ventilation cross-section is limited, so at 1500–2500 mesh the air resistance rises sharply, airflow cannot increase, and the classifier becomes the bottleneck that caps output.
Two or more classifying rotors work in parallel in the classifier head. Total ventilation area multiplies, so the same 2500-mesh powder leaves at a much higher rate — and the main machine's grinding capability is finally fully used.
The company behind the machine
Shanghai Cronus Machinery Co., Ltd. is the international sales and service subsidiary of Guilin Mining Machinery Co., Ltd. (GUIKUANG), founded in 1973. For more than 50 years the group has designed and manufactured grinding equipment — Raymond mills, ultrafine ring roller mills, vertical roller mills, crushers and complete powder production lines.
Guilin Mining Machinery is a backbone enterprise of China's Guangxi machinery industry, one of the two grinding-equipment manufacturers designated by the former Ministry of Machinery Industry, and a drafting unit of China's grinding machine standards. Today more than 10,000 customers in 30+ countries run Cronus equipment.
Working principle & structure
The CRGM mill is a closed-circuit, negative-pressure ring roller grinding system: dry grinding, built-in classification, cyclone collection and pulse-jet dust removal in one line.
Crushed material (≤20 mm) is fed evenly by a vibrating feeder and air-lock valve into the grinding chamber. An optional built-in dryer handles slightly damp feed.
The main motor drives the multi-layer turntable through a reducer. Centrifugal force presses the swinging ring rollers against the ring track; material is sheared and crushed layer by layer through 3–4 grinding zones.
A high-pressure blower pushes air in from the bottom of the ring. Fine powder is lifted with the airflow; heavy coarse particles fall back to the grinding zone automatically.
At the top, powder passes the multi-rotor classifier. Each rotor is driven by its own variable-frequency motor and sets an exact cut point — oversized particles are rejected and returned to the mill.
Qualified fines are captured by the cyclone collector and discharged by the air-lock valve; remaining dust in the exhaust is filtered by the pulse-jet bag filter before clean air exits.
Multi-head advantages
Every benefit below comes from the same change: more classifying rotors in parallel — the grinding unit itself is untouched.
A single rotor's impeller window area is fixed; at 1500–2500 mesh air resistance grows dramatically and output is strangled by the classifier. Parallel rotors multiply total ventilation area, so at the same 2500 mesh the main mill's full grinding ability is released — output is clearly higher than a single-head mill of the same size.
Each rotor runs on independent variable frequency with a uniform flow field, so coarse-particle escape is minimal. D97 is controlled precisely — clean, tight PSD that coatings and plastics-filler producers demand. A single-rotor head at high fineness suffers flow-field turbulence and lets coarse grains slip through.
Set different rotor speeds and the classifier splits the product stream into two finished powders of different mesh at the same time — no parameter changeovers, no shutdowns, one line doing the work of two. A single-head mill can only output one fineness at a time.
Efficient classification removes qualified fines immediately, so good powder no longer circulates in the chamber and is ground again for nothing. At equal fineness the whole system consumes less electricity — a direct saving on every ton produced.
When the main machine is built for heavy grinding duty (e.g. CRGM125), a single-head classifier would simply become the bottleneck of the whole line. That is why the Cronus 125 ships with a multi-head classifier as standard — the classifier always matches the mill's true potential.
Already own a single-head CRGM? The multi-head classifier is a top-of-machine upgrade — the grinding chamber, foundation and main drive stay where they are.
Head-to-head
Same grinding chamber, same rollers and rings — the entire difference lives in the classifier head above. That is why the multi-head option wins where fineness and tonnage both matter.
| Item | Single-head (1 rotor) | Multi-head (parallel rotors) |
|---|---|---|
| Classifier ventilation area | Fixed, limited by one impeller | Multiplied by the number of rotors |
| Output at 1500–2500 mesh | Choked by classifier air resistance | Main mill capacity fully released |
| Particle size distribution | Wider; coarse escape at fine cuts | Sharper cut, narrower PSD, precise D97 |
| Fineness grades per run | One | Two (independent rotor speeds) |
| Over-grinding & unit energy | Longer internal recirculation | Fines leave quickly; lower kWh/t |
| Suitability for large mills | Classifier becomes line bottleneck | Standard fit for CRGM125 and up |
| Grade changeover | Stop and re-adjust | Change rotor speed only |
Applications & materials
Typical materials include calcite, limestone, marble, dolomite, talc, pyrophyllite, barite, gypsum, kaolin, bentonite, mica, wollastonite, petroleum coke, carbon black, aluminium hydroxide and diatomite. Feed ≤20 mm, moisture ≤6%, non-flammable and non-explosive.
Factory test runs and customer site footage — real equipment, real powder.
Engineering cases
Installation, commissioning and customer visits — Cronus lines for ultrafine non-metallic powder are running across Asia, the Middle East, Africa and the Americas.
Technical data
Data below are reference values for calcite-type materials (Mohs ≤ 6, moisture ≤ 6%). Final model selection follows free material testing.
| Model | CRGM60 | CRGM80 | CRGM100 | CRGM125 |
|---|---|---|---|---|
| Ring diameter (mm) | φ600 | φ800 | φ1000 | φ1250 |
| Ring layers | 3 | 3 | 4 | 4 |
| Grinding rollers (pcs) | 12 | 21 | 28 | 32 |
| Main shaft speed (r/min) | 250–280 | 230–240 | 180–200 | 135–155 |
| Max feed size (mm) | ≤20 | |||
| Finished fineness (μm / mesh) | 5–74 200–2500 | 5–74 200–2500 | 7–74 200–2000 | 7–74 200–2000 |
| Capacity (t/h) | 0.2–3 | 0.5–4.5 | 1.8–5 | 1.5–12 |
| Main unit power (kW) | 45 | 75 | 132 | 185 |
| Classifier power (kW) | 15 | 18.5 | 30 | 75 |
| Blower power (kW) | 37 | 45 | 75 | 132 |
| Discharge valve (kW) | 0.75 | 0.75×2 | 1.1 | 1.5 |
| Screw conveyor (kW) | 2.2 | 3 | 4 | 4 |
| Total power (kW) | 101 | 143 | 244 | 401 |
| Overall dimension L×W×H (m) | 11.5×3.5×5.2 | 15.9×4.2×6.1 | 19.7×4.7×7.7 | 23.2×4.7×7.7 |
CRGM125 ships with the multi-head classifier as standard; CRGM60–100 can be configured with single- or multi-head classifiers according to your fineness and capacity targets. Note: data for reference only — contact sales for tailored configuration.
Keep the line running
Rollers, rings, turntables, pins, classifier impellers, feeders, gearboxes, filter bags and pulse valves — all available as genuine Cronus parts.
Our group runs its own casting plant — wear parts are poured, machined and heat-treated under one quality system.
Factory-original dimensions and balances. No fit-up surprises, no "almost right" impellers that ruin your cut point.
Rollers and rings are forged from special wear-resistant alloy steel — 2–3× the life of ordinary parts.
Buying from the manufacturer cuts the middle layer — competitive prices with full traceability and warranty.
FAQ
It refers to the classifier (also called analyzer) mounted on top of the mill. "Multi-head" means several classifier rotors (impellers) are connected in parallel inside one classifier, each driven by its own variable-frequency motor. The grinding chamber below — turntable, rollers and rings — is the same single grinding unit. So: single head = single-rotor classifier; multi head = multi-rotor parallel classifier head.
A single rotor's impeller ventilation cross-section is limited. At ultrafine cuts, air resistance rises sharply, total airflow cannot go up, and the classifier chokes the mill — the main machine is forced to run below its grinding capacity. With multiple rotors in parallel, the total ventilation area multiplies, so the same 2500-mesh product leaves at a significantly higher rate.
No. The grinding unit is identical. Only the classification system on top is upgraded, which is why it is also a practical retrofit for existing single-head mills.
Yes. Because each rotor is independently VFD-controlled, rotors can run at different speeds. The system then splits off two finished products of different mesh simultaneously — no downtime for parameter changes.
Brittle, non-flammable, non-explosive minerals with Mohs hardness ≤6 and moisture ≤6%: calcite, limestone, marble, dolomite, talc, pyrophyllite, barite, gypsum, kaolin, bentonite, mica, wollastonite, petroleum coke, carbon black, aluminium hydroxide, diatomite and similar non-metallic minerals.
Finished powder covers 200–2500 mesh (5–74 μm), D97 controlled precisely by rotor speed. Capacity ranges from 0.2 t/h (CRGM60 at 2500 mesh) up to about 12 t/h (CRGM125 at coarser cuts). Actual figures depend on material hardness, moisture, feed size and target residue — we confirm them with a free test grinding.
For the same ultrafine output, a ring roller mill typically delivers more than twice the capacity at roughly 30% lower energy consumption than a jet mill, with simpler maintenance and lower air-compression cost.
Jaw crusher (or similar), bucket elevator, storage hopper and feeder, the CRGM main unit with multi-head classifier, blower, cyclone collector, pulse-jet dust collector, discharge valves, screw conveyor, packing machine and PLC control cabinet. Layout is engineered to your workshop.
The whole circuit runs under negative pressure, so no dust escapes. Sound-insulated rooms and silencer design keep noise near the main unit controlled to plant standards.
With our forged wear-resistant alloy, service life is typically 2–3 times longer than standard parts. Actual life depends on material abrasiveness, moisture and hours run — we provide an inspection schedule and stocked spares so replacement is planned, not emergency.
In most cases yes — the multi-head classifier is installed on top of the existing main machine. Send us your mill model and photos for an upgrade proposal.
Standard 12-month warranty on the main body. We provide layout design, foundation drawings, on-site or remote installation supervision, commissioning, operator training, lifetime spare-parts supply and 24-hour response through our international service center in Shanghai.
After-sales service
Free grinding test on your material in our Guilin lab; capacity, D97, and wear data before you buy.
Foundation drawings, layout design, supervised erection and commissioning — on-site or remote.
Hands-on operator training covering start/stop, fineness adjustment, maintenance and safety.
Group-owned casting plant and stocked warehouse keep lead times short; export packing within days.
12-month warranty, 24-hour response from the Shanghai international service center, annual health checks.
"50 years of building mills means one thing: when your line stops, you need an answer today — not next week."Cronus International Service Center, Shanghai
Start with your material
Share your material, target fineness and capacity. Within 24 hours you receive a model recommendation, layout draft and a free test-grinding offer.