Underground mines need air — for the men, for the machines, and to dilute gas. In development headings and auxiliary ventilation, the workhorse is the contra-rotating axial fan: two impellers spinning in opposite directions inside one casing, with no stator between them.
Why two impellers?
A single axial stage has a practical pressure ceiling. Add a second, counter-rotating stage and you recover the swirl losses of the first stage — the second impeller acts as both a compressor and a straightener. Result: roughly double the pressure of a single stage in the same diameter, in a shorter package than a two-stage fan with an inter-stage duct.
What to look for in a mining auxiliary fan
- Pressure at the duty point — not just maximum. A 2×18.5 kW machine with ≈3400 Pa at 7.5 m³/s keeps long duct runs working.
- Direct drive — two motors on one shaft line, no belts to slip or replace underground.
- Spark protection — brass anti-spark rings between rotating and stationary parts for gassy mines; anti-static blade options for the impeller itself.
- Blade construction — welded steel plate blades survive impacts; cast aluminium gives a lighter rotor and tighter balance. Choose by your duty and local rules.
- Balance grade — at 2930 rpm even a small unbalance shakes the ducting. Specify ISO 1940 G4.0 and ask for the report.
Prototype data from our Ø630 machine
Our mining range is built around a CFD-developed prototype: casing Ø630 mm, 7+6 blades contra-rotating at ±2930 rpm, 7.5 m³/s at ≈3400 Pa, powered by 2×18.5 kW direct-drive motors. The machine is currently on the certification path for the Chinese coal market (MA, Ex). For overseas mines we supply to your local standard — no MA required outside China.
Mining enquiry? Tell us flow, duct Ø and gas class. Contact the mining team: WhatsApp +852 9524 8434.